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Comparison of marine debris data collected by researchers and citizen scientists: Is citizen science data worth the effort?
BIOC-06821; No of Pages 12 Biological Conservation xxx (2016) xxx–xxx
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Biological Conservation journal homepage: www.elsevier.com/locate/bioc
Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort? Tonya van der Velde a,⁎, David A. Milton a, T.J. Lawson b, Chris Wilcox c, Matt Lansdell c, Geraldine Davis d, Genevieve Perkins, Britta Denise Hardesty c a
CSIRO Oceans and Atmosphere, PO Box 2583, Brisbane, Qld. 4001, Australia CSIRO Land and Water, PO Box 312, Clayton South, Vic. 3150, Australia CSIRO Oceans and Atmosphere, PO Box 1538, Hobart, Tas. 7000, Australia d Envirodot International, PO Box 452, Flemington, Vic. 3031, Australia e Geomatics and Landscape Ecology Research Laboratory (GLEL), Department of Biology, Carleton University, Ottawa, ON, Canada b c
a r t i c l e
i n f o
Article history: Received 9 June 2015 Received in revised form 15 May 2016 Accepted 27 May 2016 Available online xxxx Keywords: Participatory research Public engagement Students Training Volunteers
a b s t r a c t As part of a national research program studying the sources, distribution, and effects of litter entering the ocean, we established a national citizen science program engaging nearly 7000 primary and secondary students, teachers and corporate participants in collecting marine debris data around Australia's coastline. Citizen scientists undertook a one-day training program, which addressed data collection skills and academic topics in the national science curriculum. A subset of teachers and corporate sponsor staff participated in an intensive multi-day training program with researchers before venturing into the field. Data collected by citizen scientists were compared with data collected by researchers at nearby locations. We found the citizen science data were of equivalent quality to those collected by researchers, but there were differences among students. Primary school students detected more debris than did older secondary students. Students detected small items (b 1 cm2), and were as accurate as researchers in identifying debris type and size categories. However, sampling approach was important — students detected more debris during quadrat searches than during strip transects. Comparing researcher effort to volunteer-collected data, citizen scientists were often more efficient (per m2) than researchers at collecting marine debris, but the results varied among methods. Researchers made more surveys within a given day (0.8 surveys/person-day). However, participants of one day programs working with secondary students or adults were nearly as efficient (0.6 surveys/personday). This study shows that engaging with citizen scientists can broaden the coverage and increase the sampling power of coastal litter and other ecological survey assessments without compromising the data. © 2016 Elsevier Ltd. All rights reserved.
1. Introduction Public participation in scientific research (citizen science), has long been used to tackle research questions that would otherwise not have been addressed due to lack of resources, time or geography (Cooper et al., 2007; Couvet et al., 2008; Dickinson et al., 2010; Irwin, 2001, Silvertown, 2009). As early as the 17th century, experts recruited nonexperts to contribute to natural history observations (Greenwood, 2007). Public participation in collecting scientific data has continued to grow (Miller-Rushing et al., 2012). This growth has been due to several factors, but particularly the development of technical tools for disseminating information about projects, as well as interacting with and ⁎ Corresponding author. E-mail address: [email protected] (T. van der Velde).
gathering data from the public. The growth of citizen science also stems from the increasing realization among researchers that the public represent a potentially low-cost source of labor, skills, computational power and even finance (Silvertown, 2009). Research funders such as the National Science Foundation in the USA and the Natural Environment Research Council in the UK now require every grant holder to undertake science outreach as part of funded projects (Silvertown, 2009). This outreach engenders accountability and enables interested persons to potentially participate in the data collection (Silvertown, 2009). Citizen science projects can involve volunteer participants from school-aged children to adults. Participants may be involved in a variety of roles including study design, data collection, processing and analysis, and dissemination of information to the broader community (Tulloch et al., 2013; Theobald et al., 2015). Citizen scientists participate in projects ranging from astronomy to air quality and from population ecology to
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Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
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biology (Greenwood, 2007, Dickinson et al., 2010, Tregidgo et al., 2013). One long term example of the value of citizen scientists is with bird monitoring. Volunteer engagement goes back as far as 1749 in Europe (Greenwood, 2007) with volunteer programs increasing the global knowledge of population changes in birds in many regions (Niven et al., 2004; Bonter and Hochachka, 2003; Vandenbosch, 2000) and with opportunities to apply this knowledge to achieve conservation outcomes. Astronomy has the largest participation rate by citizen scientists, with volunteers discovering numerous new stars and sky objects (Dickinson et al., 2010). This citizen scientist engagement has enabled collection of data beyond the normal scope of a conventional research project by greatly increasing the observation capacity available. Increasingly, citizen scientists are contributing to our understanding of large-scale environmental or conservation problems. In this study, we distinguish between paid, trained scientific staff, unpaid and untrained citizen scientists, and citizen scientists who are trained by paid scientific staff. However, as many researchers question the accuracy and precision of citizen science-collected data (Forrester et al., 2015, Crall et al., 2010, Hunter et al., 2013), validation of these data is critical (Boudreau and Yan, 2004). There are many studies that compare citizen scientist collected data and data collected by paid researchers (Finn et al., 2010; Gillett et al., 2012; Lovell et al., 2009). Typically, however, studies do not evaluate the type of training and its effectiveness. Suitably trained citizen scientists may have great potential to contribute valuable data on widespread environmental issues such as marine debris. Marine debris has been identified as an increasingly important global environmental issue, alongside other key challenges including climate change, ocean acidification and loss of biodiversity (Sutherland et al., 2010). It is estimated that more than 8.4 million tonnes of plastic waste enters our oceans annually from land based sources (Jambeck et al., 2015). Density estimates are as high as 588,000 pieces of plastic per km2 in the oceans (Law et al., 2010). The impacts of this threat on biodiversity are both broad and deep. Marine debris has been reported to have direct impacts on invertebrates, fish, amphibians, birds, reptiles, and mammals (Good et al., 2010), interacting with nearly 700 marine species at last count (Gall and Thompson, 2015) and potentially resulting in significant population level impacts on widespread or threatened marine taxa (Wilcox et al., 2015). These impacts are known to be a significant threat to the persistence of several threatened or endangered marine species and are likely to be affecting many others. For example, up to 40,000 fur seals die each year by entanglement in debris (Derraik, 2002) and entanglement and ingestion are purportedly major causes of population decline for many marine mammals (Gall and Thompson, 2015). Similarly, it is estimated that between 5000 and 15,000 turtles are entangled each year by derelict fishing gear washing ashore in northern Australia alone (Wilcox et al., 2015) and globally approximately 1/3 of all turtles have ingested plastic debris (Schuyler et al., 2014). These impacts are likely to intensify, as plastic production is expanding exponentially (Plastics Europe, 2013). The Commonwealth Scientific and Industrial Research Organisation's (CSIRO) National Marine Debris program was established to quantify the amount and types of litter that enter the marine environment and the potential impacts this litter may have on Australian wildlife. The project integrated field, modelling, genetic and biochemical marker approaches to understand the impact of marine debris on fauna at the national scale. One of the critical aspects of this program is engagement with school groups and other citizen scientist participants. This engagement had two foci. The first was to promote science education and learning through a timely and relevant topic, as the marine debris issue fits in well with mathematics, chemistry, physics, biology, oceanography and other parts of the national curriculum. Furthermore, the topic resonates with Australia's largely coastal population and the issue is engaging for students and the broader public. The
second focus was to collaborate with citizen scientists on data collection, using the opportunity to train participants in the process to increase the pool of contributors to scientific data on coastal litter and marine debris. Here, we investigated the quality of data collected by citizen science students and adults and compared that data to data collected by paid researchers. We focused on assessing the composition, distribution and abundance of marine debris from coastal litter surveys around Australia. We concentrated on comparing the marine debris data obtained from trained citizen scientists with that from paid researchers. This allowed us to evaluate the effectiveness (in terms of time) of including citizen science as a component of a national scientific investigation. Specifically we addressed three questions: 1) Are data collected by citizen scientists of similar quality to those collected by paid researchers; 2) Does investment in training citizen scientists, above a basic level, improve the quality of their data; and 3) From a return-oninvestment perspective, can involving citizen scientists increase the sampling power of scientific projects in comparison with using only paid researchers?
2. Materials and methods 2.1. Researcher surveys 2.1.1. Site selection The research team spent an intensive ten-day training period to trial methodologies, data collection approaches and to ensure consistency in data collection as well as best-practices for recording, detecting and reporting of data prior to initiation of research activities. We sampled debris at randomly selected coastal sites, located approximately every 100 km along the Australian coastline, except where access was prohibited (Fig. 1; see Hardesty et al., 2016). Coastal litter surveys applied a 2 m wide strip transect approach with surveys running perpendicular from the water's edge and continuing two meters into the continuous terrestrial vegetation. A minimum of three and maximum of 6 transects were made at each site, depending on whether litter was detected in the first three transects and substrate type(s) at each site (Appendix A). Transects were located a minimum of 50 m from the access point and from each other, stratified across the substrate types where multiple substrate types occurred at a single site (sand, boulder, mangrove, etc.; see detail in Hardesty et al., 2016).
2.1.2. Data collected We recorded the GPS location of the access point, date, name of observer(s), weather conditions, wind speed and direction, a count of people present (excluding surveyors) and time of day. For each transect we recorded the start and end times and locations and the length of transect. To account for factors that may affect debris deposition and retention, we also recorded the exposure, shape, aspect, substrate, colour, gradient, location of the dominant debris line, and the backshore type for each transect (Appendix A). To consider the potential contribution of land-based debris sources we determined the population within 5 km of each site, the population within 50 km of each site and the distance from the access point to the nearest road. Each two metre wide strip transect was surveyed by two observers side by side, recording all litter detected from standing position within a one metre wide swath. The first item encountered within each of ten equal distance length classes along the transect line in addition to material type and colour, size was recorded based upon doubling size classes from b1 cm2, 2 cm2, 4 cm2, 8 cm2, 16 cm2 and N16 cm2. This subset of items was chosen for sampling efficiency as some transects had hundreds of items. Where feasible, litter was collected and removed.
Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
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Fig. 1. Map of Australia showing the location of coastal marine debris survey sites (transects) made by CSIRO researchers (black dots) and citizen science transects and quadrat searches (pink dots). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
2.2. Citizen science surveys 2.2.1. School identification and survey site selection CSIRO Education, a school engagement arm of Australia's national research organisation, made contact with prospective teachers through a national outreach program to identify schools potentially interested in participating. Additional schools were identified by Earthwatch Australia, the collaborating organisation on the outreach aspect of the project. Teachers and students from schools in coastal Queensland, New South Wales, Victoria, South Australia, Western Australia, the Northern Territory and Tasmania were identified and participated in the program. Training of students was a core part of the engagement process. Prior to field excursions where surveys took place, litter from other survey sites was brought into the classroom and used for training students in data collection, recording and litter identification. Survey sites for participating schools were chosen based on proximity to the schools along with health and safety considerations. Sites ranged from relatively remote to urban or semi-urban. Sites tended to have sandy substrates, good local access and to occur in more populous regions. They were not randomly selected, in contrast to the sites surveyed by researchers.
2.2.2. Teacher and corporate participant training There were two levels of training for teachers who enrolled in the program: a one-day training session or a multi-day intensive training block; typically 5–7 days. The one-day program took place in schools, and engaged teachers and students simultaneously. The one-day program focused on marine debris as a topic in a lecture and activity format, and incorporated training on the coastal survey methods in the classroom. Classroom activities generally took the first half of the day. The second half of the day was devoted to data collection in the field alongside 1–2 trained professionals from CSIRO and Earthwatch.
In contrast to the one day training, some teachers participated in a multiple-day residential program during which teachers received intensive class and field-based training in marine debris issues and data collection, including in both strip transect and quadrat-based coastal litter surveys (detailed below). They also engaged in additional educational and field-based learning activities on marine debris related research questions to take such learning back to their classrooms and communities. The corporate participants (mostly Shell employees) also received the same multi-day intensive training program as the teachers, but the training events were undertaken separately. 2.2.3. Debris sampling method Marine debris sampling by primary and secondary students was undertaken in groups that widely varied in size and level of researcher supervision. Where possible, students were divided into small groups (b5) under the supervision of a researcher or intensively-trained teacher and undertook transects with methods consistent with those of researchers. For larger groups, or where there were insufficient researchers to adequately supervise transects (N 10 students per researcher), we designed an alternative sampling method (quadrat) for use by larger groups of citizen scientists (N 10) to provide opportunities for engagement with multiple participants of all ages/skill levels. The quadrat survey approach is simply a wider transect that can accommodate multiple participants simultaneously. The quadrat survey method also allows for debris items to be collected; sorting and counting occurred in the classroom. Students were divided into groups of 10 or fewer, with each group designated a specific section of the beach to survey. Quadrats were searched systematically, with observers spaced approximately 1 m apart in a line, walking back and forth across the quadrat until the entire area was surveyed. Quadrats extended approximately 30 to 50 m along the waterline, and extended from the water's edge to 2 m into the continuous terrestrial vegetation. Consistent with the transect
Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
207.4 ± 57.0 12.9 ± 0.6 15 140 7 116 830 ± 228 141 ± 14 1–5 1–10 3 28 Transect Researchers
Quadrat search
Day –
2.3 ± 1.3 4.1 ± 0.4
473.2 ± 238.8 7.3 ± 1.0 18.4 ± 1.0 57.7 ± 26.3 20 224 70 84 7 19 42 7 1892 ± 1083 103 ± 15 88 ± 4 808 ± 369 1–4 1–4 1–7 1–4 4 8 14 3 Transect Secondary students
Quadrat search
Day Multi-day Day Multi-day
1.8 ± 0.8 2.4 ± 0.4 3 ± 0.5 2.3 ± 0.9
46.3 ± 18.5 5.6 ± 1.0 – 23.5 ± 11.8 10 84 – 112 2 8 – 6 476 ± 364 78 ± 13 – 328 ± 166 1–1 2–3 – 1–2 2 3 – 4 Transect
Day Multi-day Day Multi-day
1±0 2.7 ± 0.3 – 1.5 ± 0.3
2.6 ± 0.3 7.8 ± 1.4 48.7 ± 14.3 504 55 252 54 33 13 66 ± 4 50 ± 6 1218 ± 321
Time cost (person-days) Total (surveys) Mean area surveyed ± se (m2) Range (d)
1–7 1–6 1–2 3 ± 0.4 3 ± 0.6 1.4 ± 0.2 18 11 9 Multi-day Day Multi-day
Primary students
Seventy-one teachers from Queensland, Victoria, Tasmania, New South Wales, Northern Territory and Western Australia participated in the multi-day training program. The period of training for participants or teachers did not appear to correlate with the density of marine debris recorded by each group during transects (Fig. 4a) or quadrat sampling (Fig. 4b). There was no statistically significant difference in data collection between groups receiving extended training or one day of training, for either transect or quadrat methods (P N 0.6). In addition, groups
Quadrat search
3.3. Training
Transect
Counts of debris on transects, by citizen scientists (standardized by area) did not differ significantly from litter counts detected by researchers (P N 0.7; Fig 2). However, the quadrat method yielded a significantly higher density of debris than was observed with the transect method (P b 0.05). When these data are separated into age groups, we find that the density of debris found during quadrat searches undertaken by adults were similar to those by all groups who undertook transects (Fig. 3). Secondary school students detected a significantly lower density of marine debris than other groups (P b 0.05) (Fig. 3).
Adults
3.2. Density of debris
se
Scientific staff completed 575 transects at 172 coastal sites around Australia (Fig 1; Hardesty et al., 2016). Sites were surveyed approximately every 100 km from north of Cairns to east of Broome in a clockwise fashion, except for a gap in the northernmost part of the continent, due to lack of access. Surveys took place between October 2011 and May 2013. During the same period, 156 transects and 41 quadrat searches across 45 sites were undertaken by citizen scientists (Table 1). Citizen scientist transects involved adults, primary and secondary students. Adult participants were mostly Shell employees or teachers who had engaged in a one-day or a multi-day intensive training program on marine debris and the associated data collection and interpretation (Table 1).
Mean number of surveys·d−1 ±
3.1. Comparison of transects by citizen and researchers
N (events)
3. Results
Level of training
The time cost of each marine debris sampling activity was calculated by summing the number of researcher person-days that were dedicated to each survey event. This calculation included researcher travel and preparation time as well as the contact time with students, teachers and corporate participants. Calculations also included researcher time for training and pre-survey orientation days which included health and safety checks of sites to be surveyed. Most one-day program activities involved at least two project staff with a maximum of five for selected citizen science events. The mean researcher time per sampling event was calculated from the total number of sampling events divided by the total researcher days required. The relative efficiency of each sampling method (transects and quadrat searches) was estimated by calculating the mean ± se areal coverage (m2) of each sampling and different levels of training (one day vs. multi-day training).
Survey method
2.3. Analysis of survey efficiency
Surveyors
methodology, the quadrats were located at least 50 m from the main beach access point. Wherever possible, multiple quadrats were surveyed, with each survey separated by at least 50 m. Data on site characteristics were collected as per the protocol used for the transect survey method. Once the samples were identified and measured, as with strip transects, data were then entered into a national online database.
Mean survey efficiency ± se (m2·person-day−1)
T. van der Velde et al. / Biological Conservation xxx (2016) xxx–xxx Table 1 Summary of the mean number of surveys ± se, direct time costs (in days) and mean survey efficiency (m2·person·d−1) ± se for organizing, training and undertaking marine debris surveys by primary and secondary school students and adult citizen scientists compared with surveys made by researchers within 150 km.
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Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
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Fig. 2. The mean density (items·m2 ± se) of marine debris found during citizen science transects and quadrat searches compared with nearby transects by researchers.
trained for one day or several days found similar quantities and types of debris to that found by researchers at nearby survey sites. The one exception to this pattern is the density of marine debris collected during quadrat searches. These differed among primary school students supervised by teachers with multi-day intensive or one-day training (Fig. 4b). Primary school students supervised by teachers who participated in the
Fig. 4. The mean density (items·m2 ± se) of marine debris found among (a) transects and (b) quadrat searches. Surveys were carried out by researchers, by intensively-trained (multi-day) adults, by primary and secondary student groups led by intensively trained (multi-day) teachers; and by one-day trained adults, secondary, and primary aged students.
intensive training found significantly more marine debris than did other groups (P b 0.01). 3.4. Size composition of debris The size composition of the marine debris found using the transect method differed between researchers and citizen scientists (χ25 = 30.5; P b 0.001). This result was almost entirely driven by the fact that researchers detected more of the largest debris size class (16 cm2) than expected (Fig. 5). Overall, the result suggests that the volunteers were detecting marine debris of a similar composition to that found by researchers. Both sampling groups detected mostly smaller-sized debris, consistent with a Poisson distribution. The most commonly detected debris size class was 2 × 2 cm (class 2), followed by the smallest size class (1 × 1 cm: class 1, Fig. 5). There was a significant difference between debris detected based on sampling methods for volunteer collected data; significantly more small debris items were detected using the quadrat method in comparison with the strip transect method (χ25 = 18.4; P b 0.005, Fig. 5). 3.5. Survey efficiency
Fig. 3. The mean density (items·m2 ± se) of marine debris found among transects and quadrat searches made by adults, secondary and primary school students compared with nearby transects made by researchers.
Relatively speaking, more researcher staff time was used to collect data with citizen scientists than when researchers collected data independently. The average staff time per strip or quadrat survey for project participants involved in intensive (multi-day) training programs was
Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
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Fig. 5. The relative abundance of marine debris of different size classes found during citizen science transects and quadrat searches compared with transects by researchers. Size categories: Size 1 = b1 cm2, 2 = 2 cm2, 3 = 4 cm2, 4 = 8 cm2, 5 = 16 cm2 and 6 = N16 cm2.
13.6 researcher days per survey. The number of researcher days used to support citizen scientists in one-day programs was substantially less, averaging 2.2 days per survey. There was also a substantial difference in time spent depending on the survey method, with transect surveys requiring 58% of the project staff time used to support quadrat surveys. There was relatively little difference in the staff time required to support sampling by different age groups of citizen scientists, with most of the variation in time required being due to the depth of training (multi-day vs. one-day) and sampling method (transect vs. quadrat). For instance, comparing transect sampling supported by multi-day training, secondary students required the most staff time per survey (11.8 days), followed by primary students (10.5 days) and finally adults (9.3 days). Similar patterns held across other methods and training intensities, with no clear differences in support time required across age groups. The quantity of debris detected varied widely between transects and quadrat surveys made by primary students, secondary students and adults (Table 1). All citizen science groups surveyed a larger area during quadrat surveys than transects by any group, including researchers (P b 0.05). However, there was much greater variability in survey efficiency of quadrat surveys compared with transects. Transects undertaken by citizen scientists had similar efficiency to those made by researchers, with the exception of secondary students who were significantly more efficient than researchers (P b 0.05) (Table 1).
4. Discussion Marine litter is a growing environmental issue which lends itself well to community outreach and citizen science. There are numerous clean-up programs and activities around the world that utilize the energy, enthusiasm and capability of interested members of the public (e.g. Surfrider Foundation, Ocean Conservancy's International Coastal Cleanup, Clean up Australia, others). Beach clean ups and other coastal litter work helps promote local custodianship and caretaking, with citizen scientists making valuable contributions to coastal knowledge in
communities around the world (Smith and Edgar, 2014; Hong et al., 2014; Hidalgo-Ruz and Thiel, 2013). We found that volunteer citizen scientists collect data of a comparable quality to researchers with supervision and training. In our program, volunteers undertook five tasks successfully during the marine debris sampling. First, they identified and mapped out relevant areas in which to survey. Second, they were able to find and identify anthropogenic debris. Third, they learned to recognise and accurately identify categories of marine debris within transects. Next, they were able to collect accurate and reliable data, and finally, they were able to input these data to an online national database. We found that with training support, there was no difference across age groups in the capacity of citizen scientists to accomplish these tasks, resulting in valuable data that could be integrated into the national marine debris research project. Our findings on data quality are supported by other studies of citizen scientists that have highlighted the beneficial contribution of student participation in research projects (Delaney et al., 2008; Gallaway et al., 2006; Roy et al., 2012; Eastman et al., 2014). For example, Delaney et al. (2008) assessed the accuracy of data collected by over 1000 citizen scientists to document the occurrence of invasive and native crabs in Northern America. They found that accuracy was as high as 80–95% among school children and even higher for volunteers who had university training. In contrast to our results, however, they found that accuracy increased with the age of student participants. Studies have found that the volunteer participation in scientific data collection has some potential challenges (Foster-Smith and Evans, 2003; Dickinson et al., 2010, Kobori et al., 2016). These challenges include a lack of field experience, inadequate guidelines and insufficient training prior to data collection (Foster-Smith and Evans, 2003). This highlights the importance of appropriate training and clear guidance. It is noteworthy that whilst some studies have demonstrated that the data collected has potential for error or bias, it can be powerful for examining broader patterns and longitudinal trends (Foster-Smith and Evans, 2003; Dickinson et al., 2010; Barrows et al., 2016). For example citizen scientists may be able not be able to identify freshwater macro-invertebrates to species level, but they successfully identified specimens to family level (Forte et al., 2001). We experienced similar constraints in our citizen science interactions. It was imperative to keep the sampling methodology simple so that participants could easily follow instructions and so tasks were achievable and realistic. Training was also instrumental in ensuring reliability. For instance, with student citizen scientists, prior to the field exercise, students practiced identifying, sorting and categorizing litter under guidance and supervision. Afterwards, we undertook the field excursion where ‘actual’ data were collected and subsequently analysed. We found differences in the amount of debris detected based on survey methodology with citizen scientists. Secondary school students detected significantly fewer debris items than other groups detected when using the quadrat-search method (Fig. 3). In contrast, primary schools students detected debris at nearly seven-times the rate of all other groups during quadrat-searches. It is possible that more fragments were recorded from quadrat searches than transects because of breakage. For practical constraints, not every individual item was separately bagged and labelled and it is possible that brittle items broke after collection and prior to return to the classroom for processing. However, participants that collected debris in the field were typically the same people that were sorting and counting upon return from the field. This typically happened within the same day (if not within the same 2 h period). In the infrequent instances that larger items broke into smaller bits and this was identified, items were counted as they would have been found in the field.
Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
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Secondary students detected less litter than did their younger counterparts. Anecdotally, we observed that teenage (secondary) students were sometimes less engaged in the survey process and were subject to more peer distractions. They more frequently required refocusing on the objectives and tasks at hand. In contrast, the higher density of marine debris detected by primary students making quadrat-search surveys may be attributed to their general enthusiasm and positive response toward adult supervision (particularly the visiting scientists and trained teachers; Fig. 4). The higher detection of younger students may be associated with height: younger (e.g. shorter) students had less distance from standing height to the beach surface which could have resulted in increased detectability of litter. This represents a potential bias in the data that can be accounted for in aggregating these data with data from other sources (Fig. 5). Working with citizen scientists initially required more researcher time per unit of data collected than having the researcher collect the data, due to training and supervision requirements. However, most groups of citizen scientists were more efficient at detecting marine debris than researchers undertaking transects. This result was especially apparent from the citizen scientists making quadrat searches and those who had only undertaken the one-day training. This improved mean efficiency did come at the expense of precision. There was much greater variability in sampling efficiency among citizen scientists that presumably reflected differences in their motivation or local conditions during sampling. The efficiency of researcher sampling to detect debris was also probably underestimated as most researcher sampling was undertaken in locations remote from major sources of debris. Most citizen science sampling was near urban areas, where a higher density of marine debris occurs (Hardesty et al., 2016). The five-fold increase in effort required to undertake the multi-day training events, as compared to the one-day events, did not generate any detectable improvement in survey efficiency, precision, or accuracy. These findings are similar to those by Tulloch et al. (2013) who found that increasing the investment in a volunteer monitoring program did not necessarily lead to higher quality data and more scientific publications. However, an important caveat to our results is that we are working with a snapshot of what is potentially a longer term interaction (continued data collection by citizen scientists). A number of groups have continued to contribute data independently after their initial interaction with paid research staff. Over the longer term, this will significantly increase the benefit of the time invested to train citizen scientists. This sort of initial investment, followed by a long-term return is exemplified by the Christmas Bird Count, a volunteer monitoring program coordinated by the National Audubon Society in North America. These data, collected over the last 100 years, have been shown to reflect the trends in the distribution and abundance of winter birds, allowing the agencies involved to generate distribution maps and monitor changes in bird populations over time (Sauer, 2003; Greenwood, 2007). Thus, the return on investment in the short term may not be in favour of engaging with citizen scientists. However, in projects where citizens can extend the sampling effort either in spatially or temporally, there may be significant long term value both for scientific data collection and awareness raising. Although the results from marine debris data collection by citizen scientists in this study were more variable in their efficiency and the density of debris collected, there are clearly ancillary benefits to engaging students. It has been well documented that engaging school children in citizen science projects can enhance their scientific thinking with an effective learning process that may positively enhance their attitude toward science (Hidalgo-Ruz and Thiel, 2013; Lawless and Rock, 1998; Trumbull et al., 2000; Roth and Lee, 2002). Explicit aims of this national marine debris program were to enhance
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science and mathematics education through a tangible and engaging topic, to inspire the ‘next generation’ of young scientists, and to encourage young people to think critically about how they engage with their environment. Engagement activities clearly enhanced student knowledge and awareness on the issue of marine debris, as documented through independent assessment (Fletcher, 2013). Teachers and students alike reported that participating in the program was positive and stated that participation ‘inspired behavioural changes in school communities’ and individually (Fletcher et al., 2014). Other benefits associated with the national citizen science program included school-based incentive schemes to reduce litter on the school ground (Emerald Primary School in Victoria), and corporate changes to reduce the environmental footprint initiated by participants in the program (Hardesty et al. unpublished data). Our results also highlight the potential for marine debris data collected by citizen scientists to contribute to regional or national coastal and marine debris monitoring programs. Such monitoring could then be examined to assess the performance of changes in waste management practices that are implemented (Hardesty et al. in revision). In Australia, there are already web-based portals for citizen scientists to contribute their marine debris data (e.g. http://www. marine.csiro.au/apex/f?p=120:LOGIN). Similar web-based data entry is possible with programs in other countries (Ocean Conservancy, 2016).
5. Conclusions We demonstrated that with appropriate protocols, methodology and training, citizen scientist volunteers significantly contribute to marine debris data collection and such efforts can enhance a national research program. Similarly, trained volunteers can readily contribute to other conservation research programs and monitoring. Volunteers are capable and readily able to follow instructions and collect robust reliable scientific data. We also found that in the short term, this citizen science engagement required an increased time commitment compared to data collection solely by researchers. However, the relative time of engagement per output would likely shift as participants continue collecting data beyond their initial interaction with researchers, and the ancillary community benefits are relevant for consideration. Furthermore, citizen science engagement is a relatively inexpensive way to invest in educational outcomes and attitude and behavioural change around environmental and conservation issues. For an approximately 40% increase in the time required to collect the data for this study, we engaged nearly 7000 people directly in a national research program. Given the societal benefits of community engagement, this may be one of the most cost effective environmental investments that can be made between researchers and interested members of the public. The data generated also has the potential to improve spatial and temporal coverage of the threats of debris to native fauna and thus support conservation of heavily impacted species.
Acknowledgements This study was supported by Shell's Social Investment Program, CSIRO Oceans and Atmosphere and Earthwatch Australia. The authors would like to thank the amazing educators, schoolchildren and community members who participated in the study. Without their enthusiastic participation, this project would not have been possible. We also acknowledge Q. Schuyler and K. Townsend from the University of Queensland and K Opie CSIRO for their valuable contributions. Finally, we thank Drs S. Blaber, I. van Putten and two anonymous reviewers for constructive comments on earlier drafts of this manuscript.
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Appendix A. Schools beach litter survey
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Biological Conservation journal homepage: www.elsevier.com/locate/bioc
Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort? Tonya van der Velde a,⁎, David A. Milton a, T.J. Lawson b, Chris Wilcox c, Matt Lansdell c, Geraldine Davis d, Genevieve Perkins, Britta Denise Hardesty c a
CSIRO Oceans and Atmosphere, PO Box 2583, Brisbane, Qld. 4001, Australia CSIRO Land and Water, PO Box 312, Clayton South, Vic. 3150, Australia CSIRO Oceans and Atmosphere, PO Box 1538, Hobart, Tas. 7000, Australia d Envirodot International, PO Box 452, Flemington, Vic. 3031, Australia e Geomatics and Landscape Ecology Research Laboratory (GLEL), Department of Biology, Carleton University, Ottawa, ON, Canada b c
a r t i c l e
i n f o
Article history: Received 9 June 2015 Received in revised form 15 May 2016 Accepted 27 May 2016 Available online xxxx Keywords: Participatory research Public engagement Students Training Volunteers
a b s t r a c t As part of a national research program studying the sources, distribution, and effects of litter entering the ocean, we established a national citizen science program engaging nearly 7000 primary and secondary students, teachers and corporate participants in collecting marine debris data around Australia's coastline. Citizen scientists undertook a one-day training program, which addressed data collection skills and academic topics in the national science curriculum. A subset of teachers and corporate sponsor staff participated in an intensive multi-day training program with researchers before venturing into the field. Data collected by citizen scientists were compared with data collected by researchers at nearby locations. We found the citizen science data were of equivalent quality to those collected by researchers, but there were differences among students. Primary school students detected more debris than did older secondary students. Students detected small items (b 1 cm2), and were as accurate as researchers in identifying debris type and size categories. However, sampling approach was important — students detected more debris during quadrat searches than during strip transects. Comparing researcher effort to volunteer-collected data, citizen scientists were often more efficient (per m2) than researchers at collecting marine debris, but the results varied among methods. Researchers made more surveys within a given day (0.8 surveys/person-day). However, participants of one day programs working with secondary students or adults were nearly as efficient (0.6 surveys/personday). This study shows that engaging with citizen scientists can broaden the coverage and increase the sampling power of coastal litter and other ecological survey assessments without compromising the data. © 2016 Elsevier Ltd. All rights reserved.
1. Introduction Public participation in scientific research (citizen science), has long been used to tackle research questions that would otherwise not have been addressed due to lack of resources, time or geography (Cooper et al., 2007; Couvet et al., 2008; Dickinson et al., 2010; Irwin, 2001, Silvertown, 2009). As early as the 17th century, experts recruited nonexperts to contribute to natural history observations (Greenwood, 2007). Public participation in collecting scientific data has continued to grow (Miller-Rushing et al., 2012). This growth has been due to several factors, but particularly the development of technical tools for disseminating information about projects, as well as interacting with and ⁎ Corresponding author. E-mail address: [email protected] (T. van der Velde).
gathering data from the public. The growth of citizen science also stems from the increasing realization among researchers that the public represent a potentially low-cost source of labor, skills, computational power and even finance (Silvertown, 2009). Research funders such as the National Science Foundation in the USA and the Natural Environment Research Council in the UK now require every grant holder to undertake science outreach as part of funded projects (Silvertown, 2009). This outreach engenders accountability and enables interested persons to potentially participate in the data collection (Silvertown, 2009). Citizen science projects can involve volunteer participants from school-aged children to adults. Participants may be involved in a variety of roles including study design, data collection, processing and analysis, and dissemination of information to the broader community (Tulloch et al., 2013; Theobald et al., 2015). Citizen scientists participate in projects ranging from astronomy to air quality and from population ecology to
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biology (Greenwood, 2007, Dickinson et al., 2010, Tregidgo et al., 2013). One long term example of the value of citizen scientists is with bird monitoring. Volunteer engagement goes back as far as 1749 in Europe (Greenwood, 2007) with volunteer programs increasing the global knowledge of population changes in birds in many regions (Niven et al., 2004; Bonter and Hochachka, 2003; Vandenbosch, 2000) and with opportunities to apply this knowledge to achieve conservation outcomes. Astronomy has the largest participation rate by citizen scientists, with volunteers discovering numerous new stars and sky objects (Dickinson et al., 2010). This citizen scientist engagement has enabled collection of data beyond the normal scope of a conventional research project by greatly increasing the observation capacity available. Increasingly, citizen scientists are contributing to our understanding of large-scale environmental or conservation problems. In this study, we distinguish between paid, trained scientific staff, unpaid and untrained citizen scientists, and citizen scientists who are trained by paid scientific staff. However, as many researchers question the accuracy and precision of citizen science-collected data (Forrester et al., 2015, Crall et al., 2010, Hunter et al., 2013), validation of these data is critical (Boudreau and Yan, 2004). There are many studies that compare citizen scientist collected data and data collected by paid researchers (Finn et al., 2010; Gillett et al., 2012; Lovell et al., 2009). Typically, however, studies do not evaluate the type of training and its effectiveness. Suitably trained citizen scientists may have great potential to contribute valuable data on widespread environmental issues such as marine debris. Marine debris has been identified as an increasingly important global environmental issue, alongside other key challenges including climate change, ocean acidification and loss of biodiversity (Sutherland et al., 2010). It is estimated that more than 8.4 million tonnes of plastic waste enters our oceans annually from land based sources (Jambeck et al., 2015). Density estimates are as high as 588,000 pieces of plastic per km2 in the oceans (Law et al., 2010). The impacts of this threat on biodiversity are both broad and deep. Marine debris has been reported to have direct impacts on invertebrates, fish, amphibians, birds, reptiles, and mammals (Good et al., 2010), interacting with nearly 700 marine species at last count (Gall and Thompson, 2015) and potentially resulting in significant population level impacts on widespread or threatened marine taxa (Wilcox et al., 2015). These impacts are known to be a significant threat to the persistence of several threatened or endangered marine species and are likely to be affecting many others. For example, up to 40,000 fur seals die each year by entanglement in debris (Derraik, 2002) and entanglement and ingestion are purportedly major causes of population decline for many marine mammals (Gall and Thompson, 2015). Similarly, it is estimated that between 5000 and 15,000 turtles are entangled each year by derelict fishing gear washing ashore in northern Australia alone (Wilcox et al., 2015) and globally approximately 1/3 of all turtles have ingested plastic debris (Schuyler et al., 2014). These impacts are likely to intensify, as plastic production is expanding exponentially (Plastics Europe, 2013). The Commonwealth Scientific and Industrial Research Organisation's (CSIRO) National Marine Debris program was established to quantify the amount and types of litter that enter the marine environment and the potential impacts this litter may have on Australian wildlife. The project integrated field, modelling, genetic and biochemical marker approaches to understand the impact of marine debris on fauna at the national scale. One of the critical aspects of this program is engagement with school groups and other citizen scientist participants. This engagement had two foci. The first was to promote science education and learning through a timely and relevant topic, as the marine debris issue fits in well with mathematics, chemistry, physics, biology, oceanography and other parts of the national curriculum. Furthermore, the topic resonates with Australia's largely coastal population and the issue is engaging for students and the broader public. The
second focus was to collaborate with citizen scientists on data collection, using the opportunity to train participants in the process to increase the pool of contributors to scientific data on coastal litter and marine debris. Here, we investigated the quality of data collected by citizen science students and adults and compared that data to data collected by paid researchers. We focused on assessing the composition, distribution and abundance of marine debris from coastal litter surveys around Australia. We concentrated on comparing the marine debris data obtained from trained citizen scientists with that from paid researchers. This allowed us to evaluate the effectiveness (in terms of time) of including citizen science as a component of a national scientific investigation. Specifically we addressed three questions: 1) Are data collected by citizen scientists of similar quality to those collected by paid researchers; 2) Does investment in training citizen scientists, above a basic level, improve the quality of their data; and 3) From a return-oninvestment perspective, can involving citizen scientists increase the sampling power of scientific projects in comparison with using only paid researchers?
2. Materials and methods 2.1. Researcher surveys 2.1.1. Site selection The research team spent an intensive ten-day training period to trial methodologies, data collection approaches and to ensure consistency in data collection as well as best-practices for recording, detecting and reporting of data prior to initiation of research activities. We sampled debris at randomly selected coastal sites, located approximately every 100 km along the Australian coastline, except where access was prohibited (Fig. 1; see Hardesty et al., 2016). Coastal litter surveys applied a 2 m wide strip transect approach with surveys running perpendicular from the water's edge and continuing two meters into the continuous terrestrial vegetation. A minimum of three and maximum of 6 transects were made at each site, depending on whether litter was detected in the first three transects and substrate type(s) at each site (Appendix A). Transects were located a minimum of 50 m from the access point and from each other, stratified across the substrate types where multiple substrate types occurred at a single site (sand, boulder, mangrove, etc.; see detail in Hardesty et al., 2016).
2.1.2. Data collected We recorded the GPS location of the access point, date, name of observer(s), weather conditions, wind speed and direction, a count of people present (excluding surveyors) and time of day. For each transect we recorded the start and end times and locations and the length of transect. To account for factors that may affect debris deposition and retention, we also recorded the exposure, shape, aspect, substrate, colour, gradient, location of the dominant debris line, and the backshore type for each transect (Appendix A). To consider the potential contribution of land-based debris sources we determined the population within 5 km of each site, the population within 50 km of each site and the distance from the access point to the nearest road. Each two metre wide strip transect was surveyed by two observers side by side, recording all litter detected from standing position within a one metre wide swath. The first item encountered within each of ten equal distance length classes along the transect line in addition to material type and colour, size was recorded based upon doubling size classes from b1 cm2, 2 cm2, 4 cm2, 8 cm2, 16 cm2 and N16 cm2. This subset of items was chosen for sampling efficiency as some transects had hundreds of items. Where feasible, litter was collected and removed.
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Fig. 1. Map of Australia showing the location of coastal marine debris survey sites (transects) made by CSIRO researchers (black dots) and citizen science transects and quadrat searches (pink dots). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
2.2. Citizen science surveys 2.2.1. School identification and survey site selection CSIRO Education, a school engagement arm of Australia's national research organisation, made contact with prospective teachers through a national outreach program to identify schools potentially interested in participating. Additional schools were identified by Earthwatch Australia, the collaborating organisation on the outreach aspect of the project. Teachers and students from schools in coastal Queensland, New South Wales, Victoria, South Australia, Western Australia, the Northern Territory and Tasmania were identified and participated in the program. Training of students was a core part of the engagement process. Prior to field excursions where surveys took place, litter from other survey sites was brought into the classroom and used for training students in data collection, recording and litter identification. Survey sites for participating schools were chosen based on proximity to the schools along with health and safety considerations. Sites ranged from relatively remote to urban or semi-urban. Sites tended to have sandy substrates, good local access and to occur in more populous regions. They were not randomly selected, in contrast to the sites surveyed by researchers.
2.2.2. Teacher and corporate participant training There were two levels of training for teachers who enrolled in the program: a one-day training session or a multi-day intensive training block; typically 5–7 days. The one-day program took place in schools, and engaged teachers and students simultaneously. The one-day program focused on marine debris as a topic in a lecture and activity format, and incorporated training on the coastal survey methods in the classroom. Classroom activities generally took the first half of the day. The second half of the day was devoted to data collection in the field alongside 1–2 trained professionals from CSIRO and Earthwatch.
In contrast to the one day training, some teachers participated in a multiple-day residential program during which teachers received intensive class and field-based training in marine debris issues and data collection, including in both strip transect and quadrat-based coastal litter surveys (detailed below). They also engaged in additional educational and field-based learning activities on marine debris related research questions to take such learning back to their classrooms and communities. The corporate participants (mostly Shell employees) also received the same multi-day intensive training program as the teachers, but the training events were undertaken separately. 2.2.3. Debris sampling method Marine debris sampling by primary and secondary students was undertaken in groups that widely varied in size and level of researcher supervision. Where possible, students were divided into small groups (b5) under the supervision of a researcher or intensively-trained teacher and undertook transects with methods consistent with those of researchers. For larger groups, or where there were insufficient researchers to adequately supervise transects (N 10 students per researcher), we designed an alternative sampling method (quadrat) for use by larger groups of citizen scientists (N 10) to provide opportunities for engagement with multiple participants of all ages/skill levels. The quadrat survey approach is simply a wider transect that can accommodate multiple participants simultaneously. The quadrat survey method also allows for debris items to be collected; sorting and counting occurred in the classroom. Students were divided into groups of 10 or fewer, with each group designated a specific section of the beach to survey. Quadrats were searched systematically, with observers spaced approximately 1 m apart in a line, walking back and forth across the quadrat until the entire area was surveyed. Quadrats extended approximately 30 to 50 m along the waterline, and extended from the water's edge to 2 m into the continuous terrestrial vegetation. Consistent with the transect
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207.4 ± 57.0 12.9 ± 0.6 15 140 7 116 830 ± 228 141 ± 14 1–5 1–10 3 28 Transect Researchers
Quadrat search
Day –
2.3 ± 1.3 4.1 ± 0.4
473.2 ± 238.8 7.3 ± 1.0 18.4 ± 1.0 57.7 ± 26.3 20 224 70 84 7 19 42 7 1892 ± 1083 103 ± 15 88 ± 4 808 ± 369 1–4 1–4 1–7 1–4 4 8 14 3 Transect Secondary students
Quadrat search
Day Multi-day Day Multi-day
1.8 ± 0.8 2.4 ± 0.4 3 ± 0.5 2.3 ± 0.9
46.3 ± 18.5 5.6 ± 1.0 – 23.5 ± 11.8 10 84 – 112 2 8 – 6 476 ± 364 78 ± 13 – 328 ± 166 1–1 2–3 – 1–2 2 3 – 4 Transect
Day Multi-day Day Multi-day
1±0 2.7 ± 0.3 – 1.5 ± 0.3
2.6 ± 0.3 7.8 ± 1.4 48.7 ± 14.3 504 55 252 54 33 13 66 ± 4 50 ± 6 1218 ± 321
Time cost (person-days) Total (surveys) Mean area surveyed ± se (m2) Range (d)
1–7 1–6 1–2 3 ± 0.4 3 ± 0.6 1.4 ± 0.2 18 11 9 Multi-day Day Multi-day
Primary students
Seventy-one teachers from Queensland, Victoria, Tasmania, New South Wales, Northern Territory and Western Australia participated in the multi-day training program. The period of training for participants or teachers did not appear to correlate with the density of marine debris recorded by each group during transects (Fig. 4a) or quadrat sampling (Fig. 4b). There was no statistically significant difference in data collection between groups receiving extended training or one day of training, for either transect or quadrat methods (P N 0.6). In addition, groups
Quadrat search
3.3. Training
Transect
Counts of debris on transects, by citizen scientists (standardized by area) did not differ significantly from litter counts detected by researchers (P N 0.7; Fig 2). However, the quadrat method yielded a significantly higher density of debris than was observed with the transect method (P b 0.05). When these data are separated into age groups, we find that the density of debris found during quadrat searches undertaken by adults were similar to those by all groups who undertook transects (Fig. 3). Secondary school students detected a significantly lower density of marine debris than other groups (P b 0.05) (Fig. 3).
Adults
3.2. Density of debris
se
Scientific staff completed 575 transects at 172 coastal sites around Australia (Fig 1; Hardesty et al., 2016). Sites were surveyed approximately every 100 km from north of Cairns to east of Broome in a clockwise fashion, except for a gap in the northernmost part of the continent, due to lack of access. Surveys took place between October 2011 and May 2013. During the same period, 156 transects and 41 quadrat searches across 45 sites were undertaken by citizen scientists (Table 1). Citizen scientist transects involved adults, primary and secondary students. Adult participants were mostly Shell employees or teachers who had engaged in a one-day or a multi-day intensive training program on marine debris and the associated data collection and interpretation (Table 1).
Mean number of surveys·d−1 ±
3.1. Comparison of transects by citizen and researchers
N (events)
3. Results
Level of training
The time cost of each marine debris sampling activity was calculated by summing the number of researcher person-days that were dedicated to each survey event. This calculation included researcher travel and preparation time as well as the contact time with students, teachers and corporate participants. Calculations also included researcher time for training and pre-survey orientation days which included health and safety checks of sites to be surveyed. Most one-day program activities involved at least two project staff with a maximum of five for selected citizen science events. The mean researcher time per sampling event was calculated from the total number of sampling events divided by the total researcher days required. The relative efficiency of each sampling method (transects and quadrat searches) was estimated by calculating the mean ± se areal coverage (m2) of each sampling and different levels of training (one day vs. multi-day training).
Survey method
2.3. Analysis of survey efficiency
Surveyors
methodology, the quadrats were located at least 50 m from the main beach access point. Wherever possible, multiple quadrats were surveyed, with each survey separated by at least 50 m. Data on site characteristics were collected as per the protocol used for the transect survey method. Once the samples were identified and measured, as with strip transects, data were then entered into a national online database.
Mean survey efficiency ± se (m2·person-day−1)
T. van der Velde et al. / Biological Conservation xxx (2016) xxx–xxx Table 1 Summary of the mean number of surveys ± se, direct time costs (in days) and mean survey efficiency (m2·person·d−1) ± se for organizing, training and undertaking marine debris surveys by primary and secondary school students and adult citizen scientists compared with surveys made by researchers within 150 km.
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Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
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Fig. 2. The mean density (items·m2 ± se) of marine debris found during citizen science transects and quadrat searches compared with nearby transects by researchers.
trained for one day or several days found similar quantities and types of debris to that found by researchers at nearby survey sites. The one exception to this pattern is the density of marine debris collected during quadrat searches. These differed among primary school students supervised by teachers with multi-day intensive or one-day training (Fig. 4b). Primary school students supervised by teachers who participated in the
Fig. 4. The mean density (items·m2 ± se) of marine debris found among (a) transects and (b) quadrat searches. Surveys were carried out by researchers, by intensively-trained (multi-day) adults, by primary and secondary student groups led by intensively trained (multi-day) teachers; and by one-day trained adults, secondary, and primary aged students.
intensive training found significantly more marine debris than did other groups (P b 0.01). 3.4. Size composition of debris The size composition of the marine debris found using the transect method differed between researchers and citizen scientists (χ25 = 30.5; P b 0.001). This result was almost entirely driven by the fact that researchers detected more of the largest debris size class (16 cm2) than expected (Fig. 5). Overall, the result suggests that the volunteers were detecting marine debris of a similar composition to that found by researchers. Both sampling groups detected mostly smaller-sized debris, consistent with a Poisson distribution. The most commonly detected debris size class was 2 × 2 cm (class 2), followed by the smallest size class (1 × 1 cm: class 1, Fig. 5). There was a significant difference between debris detected based on sampling methods for volunteer collected data; significantly more small debris items were detected using the quadrat method in comparison with the strip transect method (χ25 = 18.4; P b 0.005, Fig. 5). 3.5. Survey efficiency
Fig. 3. The mean density (items·m2 ± se) of marine debris found among transects and quadrat searches made by adults, secondary and primary school students compared with nearby transects made by researchers.
Relatively speaking, more researcher staff time was used to collect data with citizen scientists than when researchers collected data independently. The average staff time per strip or quadrat survey for project participants involved in intensive (multi-day) training programs was
Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
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Fig. 5. The relative abundance of marine debris of different size classes found during citizen science transects and quadrat searches compared with transects by researchers. Size categories: Size 1 = b1 cm2, 2 = 2 cm2, 3 = 4 cm2, 4 = 8 cm2, 5 = 16 cm2 and 6 = N16 cm2.
13.6 researcher days per survey. The number of researcher days used to support citizen scientists in one-day programs was substantially less, averaging 2.2 days per survey. There was also a substantial difference in time spent depending on the survey method, with transect surveys requiring 58% of the project staff time used to support quadrat surveys. There was relatively little difference in the staff time required to support sampling by different age groups of citizen scientists, with most of the variation in time required being due to the depth of training (multi-day vs. one-day) and sampling method (transect vs. quadrat). For instance, comparing transect sampling supported by multi-day training, secondary students required the most staff time per survey (11.8 days), followed by primary students (10.5 days) and finally adults (9.3 days). Similar patterns held across other methods and training intensities, with no clear differences in support time required across age groups. The quantity of debris detected varied widely between transects and quadrat surveys made by primary students, secondary students and adults (Table 1). All citizen science groups surveyed a larger area during quadrat surveys than transects by any group, including researchers (P b 0.05). However, there was much greater variability in survey efficiency of quadrat surveys compared with transects. Transects undertaken by citizen scientists had similar efficiency to those made by researchers, with the exception of secondary students who were significantly more efficient than researchers (P b 0.05) (Table 1).
4. Discussion Marine litter is a growing environmental issue which lends itself well to community outreach and citizen science. There are numerous clean-up programs and activities around the world that utilize the energy, enthusiasm and capability of interested members of the public (e.g. Surfrider Foundation, Ocean Conservancy's International Coastal Cleanup, Clean up Australia, others). Beach clean ups and other coastal litter work helps promote local custodianship and caretaking, with citizen scientists making valuable contributions to coastal knowledge in
communities around the world (Smith and Edgar, 2014; Hong et al., 2014; Hidalgo-Ruz and Thiel, 2013). We found that volunteer citizen scientists collect data of a comparable quality to researchers with supervision and training. In our program, volunteers undertook five tasks successfully during the marine debris sampling. First, they identified and mapped out relevant areas in which to survey. Second, they were able to find and identify anthropogenic debris. Third, they learned to recognise and accurately identify categories of marine debris within transects. Next, they were able to collect accurate and reliable data, and finally, they were able to input these data to an online national database. We found that with training support, there was no difference across age groups in the capacity of citizen scientists to accomplish these tasks, resulting in valuable data that could be integrated into the national marine debris research project. Our findings on data quality are supported by other studies of citizen scientists that have highlighted the beneficial contribution of student participation in research projects (Delaney et al., 2008; Gallaway et al., 2006; Roy et al., 2012; Eastman et al., 2014). For example, Delaney et al. (2008) assessed the accuracy of data collected by over 1000 citizen scientists to document the occurrence of invasive and native crabs in Northern America. They found that accuracy was as high as 80–95% among school children and even higher for volunteers who had university training. In contrast to our results, however, they found that accuracy increased with the age of student participants. Studies have found that the volunteer participation in scientific data collection has some potential challenges (Foster-Smith and Evans, 2003; Dickinson et al., 2010, Kobori et al., 2016). These challenges include a lack of field experience, inadequate guidelines and insufficient training prior to data collection (Foster-Smith and Evans, 2003). This highlights the importance of appropriate training and clear guidance. It is noteworthy that whilst some studies have demonstrated that the data collected has potential for error or bias, it can be powerful for examining broader patterns and longitudinal trends (Foster-Smith and Evans, 2003; Dickinson et al., 2010; Barrows et al., 2016). For example citizen scientists may be able not be able to identify freshwater macro-invertebrates to species level, but they successfully identified specimens to family level (Forte et al., 2001). We experienced similar constraints in our citizen science interactions. It was imperative to keep the sampling methodology simple so that participants could easily follow instructions and so tasks were achievable and realistic. Training was also instrumental in ensuring reliability. For instance, with student citizen scientists, prior to the field exercise, students practiced identifying, sorting and categorizing litter under guidance and supervision. Afterwards, we undertook the field excursion where ‘actual’ data were collected and subsequently analysed. We found differences in the amount of debris detected based on survey methodology with citizen scientists. Secondary school students detected significantly fewer debris items than other groups detected when using the quadrat-search method (Fig. 3). In contrast, primary schools students detected debris at nearly seven-times the rate of all other groups during quadrat-searches. It is possible that more fragments were recorded from quadrat searches than transects because of breakage. For practical constraints, not every individual item was separately bagged and labelled and it is possible that brittle items broke after collection and prior to return to the classroom for processing. However, participants that collected debris in the field were typically the same people that were sorting and counting upon return from the field. This typically happened within the same day (if not within the same 2 h period). In the infrequent instances that larger items broke into smaller bits and this was identified, items were counted as they would have been found in the field.
Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
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Secondary students detected less litter than did their younger counterparts. Anecdotally, we observed that teenage (secondary) students were sometimes less engaged in the survey process and were subject to more peer distractions. They more frequently required refocusing on the objectives and tasks at hand. In contrast, the higher density of marine debris detected by primary students making quadrat-search surveys may be attributed to their general enthusiasm and positive response toward adult supervision (particularly the visiting scientists and trained teachers; Fig. 4). The higher detection of younger students may be associated with height: younger (e.g. shorter) students had less distance from standing height to the beach surface which could have resulted in increased detectability of litter. This represents a potential bias in the data that can be accounted for in aggregating these data with data from other sources (Fig. 5). Working with citizen scientists initially required more researcher time per unit of data collected than having the researcher collect the data, due to training and supervision requirements. However, most groups of citizen scientists were more efficient at detecting marine debris than researchers undertaking transects. This result was especially apparent from the citizen scientists making quadrat searches and those who had only undertaken the one-day training. This improved mean efficiency did come at the expense of precision. There was much greater variability in sampling efficiency among citizen scientists that presumably reflected differences in their motivation or local conditions during sampling. The efficiency of researcher sampling to detect debris was also probably underestimated as most researcher sampling was undertaken in locations remote from major sources of debris. Most citizen science sampling was near urban areas, where a higher density of marine debris occurs (Hardesty et al., 2016). The five-fold increase in effort required to undertake the multi-day training events, as compared to the one-day events, did not generate any detectable improvement in survey efficiency, precision, or accuracy. These findings are similar to those by Tulloch et al. (2013) who found that increasing the investment in a volunteer monitoring program did not necessarily lead to higher quality data and more scientific publications. However, an important caveat to our results is that we are working with a snapshot of what is potentially a longer term interaction (continued data collection by citizen scientists). A number of groups have continued to contribute data independently after their initial interaction with paid research staff. Over the longer term, this will significantly increase the benefit of the time invested to train citizen scientists. This sort of initial investment, followed by a long-term return is exemplified by the Christmas Bird Count, a volunteer monitoring program coordinated by the National Audubon Society in North America. These data, collected over the last 100 years, have been shown to reflect the trends in the distribution and abundance of winter birds, allowing the agencies involved to generate distribution maps and monitor changes in bird populations over time (Sauer, 2003; Greenwood, 2007). Thus, the return on investment in the short term may not be in favour of engaging with citizen scientists. However, in projects where citizens can extend the sampling effort either in spatially or temporally, there may be significant long term value both for scientific data collection and awareness raising. Although the results from marine debris data collection by citizen scientists in this study were more variable in their efficiency and the density of debris collected, there are clearly ancillary benefits to engaging students. It has been well documented that engaging school children in citizen science projects can enhance their scientific thinking with an effective learning process that may positively enhance their attitude toward science (Hidalgo-Ruz and Thiel, 2013; Lawless and Rock, 1998; Trumbull et al., 2000; Roth and Lee, 2002). Explicit aims of this national marine debris program were to enhance
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science and mathematics education through a tangible and engaging topic, to inspire the ‘next generation’ of young scientists, and to encourage young people to think critically about how they engage with their environment. Engagement activities clearly enhanced student knowledge and awareness on the issue of marine debris, as documented through independent assessment (Fletcher, 2013). Teachers and students alike reported that participating in the program was positive and stated that participation ‘inspired behavioural changes in school communities’ and individually (Fletcher et al., 2014). Other benefits associated with the national citizen science program included school-based incentive schemes to reduce litter on the school ground (Emerald Primary School in Victoria), and corporate changes to reduce the environmental footprint initiated by participants in the program (Hardesty et al. unpublished data). Our results also highlight the potential for marine debris data collected by citizen scientists to contribute to regional or national coastal and marine debris monitoring programs. Such monitoring could then be examined to assess the performance of changes in waste management practices that are implemented (Hardesty et al. in revision). In Australia, there are already web-based portals for citizen scientists to contribute their marine debris data (e.g. http://www. marine.csiro.au/apex/f?p=120:LOGIN). Similar web-based data entry is possible with programs in other countries (Ocean Conservancy, 2016).
5. Conclusions We demonstrated that with appropriate protocols, methodology and training, citizen scientist volunteers significantly contribute to marine debris data collection and such efforts can enhance a national research program. Similarly, trained volunteers can readily contribute to other conservation research programs and monitoring. Volunteers are capable and readily able to follow instructions and collect robust reliable scientific data. We also found that in the short term, this citizen science engagement required an increased time commitment compared to data collection solely by researchers. However, the relative time of engagement per output would likely shift as participants continue collecting data beyond their initial interaction with researchers, and the ancillary community benefits are relevant for consideration. Furthermore, citizen science engagement is a relatively inexpensive way to invest in educational outcomes and attitude and behavioural change around environmental and conservation issues. For an approximately 40% increase in the time required to collect the data for this study, we engaged nearly 7000 people directly in a national research program. Given the societal benefits of community engagement, this may be one of the most cost effective environmental investments that can be made between researchers and interested members of the public. The data generated also has the potential to improve spatial and temporal coverage of the threats of debris to native fauna and thus support conservation of heavily impacted species.
Acknowledgements This study was supported by Shell's Social Investment Program, CSIRO Oceans and Atmosphere and Earthwatch Australia. The authors would like to thank the amazing educators, schoolchildren and community members who participated in the study. Without their enthusiastic participation, this project would not have been possible. We also acknowledge Q. Schuyler and K. Townsend from the University of Queensland and K Opie CSIRO for their valuable contributions. Finally, we thank Drs S. Blaber, I. van Putten and two anonymous reviewers for constructive comments on earlier drafts of this manuscript.
Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025
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Appendix A. Schools beach litter survey
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Please cite this article as: van der Velde, T., et al., Comparison of marine debris data collected by researchers and citizen scientist: Is citizen science data worth the effort?, Biological Conservation (2016), http://dx.doi.org/10.1016/j.biocon.2016.05.025