Changes in aquatic plants in the Italian volcanic-lake system detected using current data and historical records

Aquatic Botany 112 (2014) 41–47

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Changes in aquatic plants in the Italian volcanic-lake system detected using current data and historical records M.M. Azzella a,∗ , L. Rosati b , M. Iberite a , R. Bolpagni c , C. Blasi a a b c

Department of Environmental Biology, Sapienza University of Rome, Italy Department of Biology, Plant Protection and Agro-Forestry Biotechnologies, University of Basilicata, Italy Department of Life Sciences, University of Parma, Italy

a r t i c l e

i n f o

Article history: Received 19 September 2012 Received in revised form 11 July 2013 Accepted 14 July 2013 Available online 2 August 2013 Keywords: Macrophytes Species richness Plant functional groups Regime shift Long-term investigation Mediterranean lakes

a b s t r a c t Lake littoral ecosystems help to preserve a significant degree of local and regional species richness. However, lakes are subjected to a range of human impacts that dramatically affect the local biota structurally and functionally. Unfortunately, the data available for numerous taxonomic groups in many river and lake systems are still somewhat scanty, especially in the Mediterranean area. We conducted a floristic study in 2010 and compared our data with historical data recorded over the last century (1908–2006) in six Italian volcanic lakes (central-southern Italy). Floristic data about charophytes and vascular plants were collected according to standardized sampling procedures along randomly selected transects and were partitioned into four functional groups (emergent species, floating-leaved, submerged and free-floating macrophytes). A total of 49 aquatic taxa was recorded, including 11 taxa of charophytes, emphasizing the contribution of local stoneworts to regional and European species richness. Temporal trends in macrophyte species richness and distribution over the last century mirrored trends in lakeshore development and catchment land use, and water quality. In the long term, a clear reduction in emergent species and submerged macrophytes richness was recorded in some lakes; on the other hand, in recent decades a progressive improvement of water quality supports the partial recovery of aquatic plant richness in others. As a result, the loss of native aquatic plants is concentrated along the lakeshores and in the first meters of depth. © 2013 Elsevier B.V. All rights reserved.

1. Introduction Lacustrine littoral environments have experienced a dramatic reduction in extent and a well-documented decline in quality and functionality over the last two centuries (Sala et al., 2000; Jenkins, 2003; Dudgeon et al., 2006; Goldyn, 2010; Mäemets et al., 2010; Chappuis et al., 2011). Water use, shoreline changes and urban development have seriously damaged and jeopardized riparian and littoral aquatic plant communities (Schmieder, 2004; Jeppesen et al., 2011; Bresciani et al., 2012), leading to critical regime shifts in primary production (Scheffer et al., 2001; Sayer et al., 2010; Hicks and Frost, 2011). All European countries are expected to assess the ecological status of their inland water bodies according to the European Water Framework Directive (WFD 2000/60 CE), taking into account

∗ Corresponding author at: Department of Environmental Biology, Sapienza University of Rome, p.le A. Moro 5, 00185, Italy. Tel.: +39 06 49912866; fax: +39 06 49912420. E-mail addresses: [email protected], [email protected] (M.M. Azzella). 0304-3770/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aquabot.2013.07.005

macrophytes as a Biological Quality Element (Penning et al., 2008; Søndergaard et al., 2010). The lack of macrophyte historical data, particularly in the Mediterranean region (Beklioglu et al., 2007; Bolpagni et al., 2013a,b; Manolaki and Papastergiadou, 2012), hampers the effectiveness of conservation strategies as well as the application of WFD-mandated ecological indexing procedures. Furthermore, historical data are easily affected by biases as well as by irregular and non-comparable time-series data or by differences in sampling techniques. While bearing all these issues in mind, we believe that historical data offer valuable information on changes that occur over time in plant species richness of lacustrine environments. Moreover historical data are often the only information available to define the “pristine” conditions of lakes, important to evaluate the “distance” between current conditions and pre-human-impact ones. In 2009, we undertook a research project designed to characterize and assess aquatic plant species and habitats of the Italian volcanic-lake system in order to fill the gaps in current knowledge and to lay the foundations for further systematic ecological investigations and monitoring (Dengler et al., 2011; Azzella et al., 2012). The data available on the flora and fauna within this lake system generally highlighted the occurrence of rapid changes in

Ar (km )

21.6 17.2 123.6 24.1 34.0 22.1 8.7 8.1 7.4 7.7 8.8 8.0 302 494 398 318 190 401 3.6 4.1 3.4 3.1 2.3 2.4 556 690 1262 1326 932 965

pHb Condb (␮S cm−1 20 ◦ C) Alkb (meq l−1 ) Ma (m s.l.m.)

Hydrochemical

a

a

b

Data from Tartari et al., 2004. Data collected in 2010 and analyzed by IRSA-CNR (analysis method in Legnani et al., 2005).

47.6 121.0 7.0 – 7.3 17.0 464.3 8922.0 3.4 38.0 32.5 268.0 77 78 8 23 20 22 170 146 35 38 34 50 6.0 114.5 0.4 0.2 1.7 12.1 Albano Bolsena L. Grande L. Piccolo Nemi Vico

293 305 656 658 318 507

Rt (year)

9.7 273.0 4.0 1.3 10.5 42.0

2 a a

Catchment Va (106 m3 ) mda (m) Mda (m)

The Italian volcanic-lake system, located between the northern sector of the Lazio region and Basilicata (Fig. 1), contains 94% of the freshwater in central and southern Italy, 80% of the deep lakes within the Mediterranean coastal region and 42% of the area occupied by deep lakes, as defined in accordance with the WFD (Mediterranean GIG). In this study, the lakes were selected according to their average depth (≥15 m) and availability of historical data (Table 1 and Appendix A). We thus narrowed our investigation to six waterbodies: Bolsena, Vico, Albano, Nemi, Lago Grande and Lago Piccolo. The selected lakes are caldera lakes (Wetzel, 2001) with no volcanic activity (Pasternack and Varekamp, 1997). Lakes ranged from small (Monticchio lakes: Piccolo and Grande; 0.2 and 0.4 km2 , respectively) to large (Bolsena; 114.5 km2 ), and were all located in a hilly landscape (∼300–650 m a.s.l.) (Table 1). With the exception of Nemi, the lakes all display conductivities greater than 300 ␮S cm−1 ; the alkalinity values range from 2.4 to 4.1 meq l−1 (Vico and Bolsena, respectively) (Table 1). Bolsena, which is the largest European volcanic lake, is located approximately 90 km north-east of Rome; Vico lies 50 km north-east of Rome and belongs to the “Cimino” volcanic complex; Nemi and Albano are located 30 km south of Rome and belong to the “Castelli Romani” volcanic complex. Lastly, the two lakes of Monticchio (Lago Piccolo and Lago Grande) are located in the northern corner of the Basilicata region (Fig. 1). Overall, the historical presence of well-developed charophytes beds recorded in the few existing vegetation descriptions (Carollo et al., 1974; Iberite et al., 1995, Iberite, 2007) indicate that the majority of the volcanic lakes considered for the purposes of this study are Chara-lake type (Almquist, 1929; Jensén, 1979). Consequently, this study may, despite being focused on the Italian volcanic-lake system, shed light more generally on the ecological dynamics in deep “limestone lakes” in central and southern Europe (Azzella et al., 2013).

Ala (m s.l.m.)

2.1. Study area

Ara (km2 )

2. Materials and methods

Lake

the trophic status of lakes since the mid 20th century, a phenomenon that is likely to be closely related to marked water-level fluctuations and increased water nutrient availability (Marchesoni, 1940; Avena and Scoppola, 1987; Margaritora, 1992; Margaritora et al., 2003; Mastrantuono and Sforza, 2008; Ellwood et al., 2009). We therefore hypothesized that the Italian volcanic-lake system has suffered a general loss in the occurrence and richness of submerged macrophytes as well as a reduction in the maximum depth of macrophyte colonization (Zc ) as a result of a worsening in water quality (e.g. nutrient enrichment, phytoplankton blooms and poor water transparency), riparian habitat simplification (e.g. urban expansion and recreational activities) and mismanagement of the water resource (e.g. water-level fluctuations). To verify these hypotheses, we collected all the historical data available on aquatic flora, human alterations in lake catchment areas, riparian areas and water levels, nutrient inputs and trophic status of waters (published and unpublished) since the early 20th century. During the 2010 growing season, we carried out detailed flora surveys on colonized littoral belts (e.g. euphotic zones). The aim of these investigations was to collect data on the spatial and temporal patterns of macrophyte dynamics in a significant number of Mediterranean deep lakes. The study had two main objectives: (i) to assess current aquatic species richness and distribution; (ii) to shed light on changes in species richness and occurrence over the last century.

TPb (␮g l−1 )

M.M. Azzella et al. / Aquatic Botany 112 (2014) 41–47 Table 1 Morphometric characteristics and physico-chemical features of Italian volcanic lakes (with measure units). Hydrochemical data for the entire water column were collected during winter and were assessed by CNR-IRSA; Ar = area, Al = altitude, Md = max depth, md = mean depth, V = volume, Rt = renewal time, Ma = max altitude, Alk = alkalinity, Cond = conductivity, TP = total phosphorus.

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M.M. Azzella et al. / Aquatic Botany 112 (2014) 41–47

43

Fig. 1. Study area; all the Italian volcanic lakes are shown.

2.2. Data collection Historical data on aquatic plants were collected from previous studies. In the present investigation, we only considered lakes for which quantitative data on aquatic plants were available, excluding lakes for which macrophytes were analyzed only in relation to zoobenthos or food webs (Appendix A). The floristic data in this study were collected during the 2010 growing season (July–September) using the macrophyte survey method developed to analyze deep circular-shaped lakes according to the WFD requirements (Azzella et al., 2013). Briefly, we sampled a representative number of transects for each lake on the basis of the size of the lakes. Data on macrophyte species occurrence and abundances were then collected from each 1-m depth interval up to the maximum colonization depth following the depth gradient. An underwater camera connected to a monitor placed on the boat was used to assess species presence, while a double row rake was used

to collect samples to help with macrophyte species identification. The effectiveness of this approach was assessed using resampling procedures according to Gotelli and Colwell (2010). Overall, our approach identifies more than 75% of the overall species richness. The nomenclature of vascular plants adopted in this study follows Conti et al. (2005), while that of charophytes follows Bazzichelli and Abdelahad (2009). A detailed analysis was performed to investigate the evolution of the main human impacts that have affected the Italian volcaniclake system since the late 19th century. At the catchment level, we collected data concerning: (i) the increase in the total number of inhabitants since 1891 every 20 years (source ISTAT, 2013 – the Italian National Institute of Statistics) in the municipalities around the lakes, and (ii) the changes in land use (considering exclusively the main land cover types: urban areas, agricultural areas, orchard areas and natural areas) from 1880 to 2010 using historical maps and aerial images (Lazio Region, 2007; ISTAT, 2013);

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for each lake, we reconstructed (iii) the evolution of the water level fluctuations, considering the levels recorded in the period 1880–1900 as a benchmark, and (iv) the changes in trophic conditions (Lazio Region, 2007). All the data, with the exception of the number of inhabitants, are relative to six time intervals. In addition, we conducted a rough efficiency assessment of local wastewater treatment facilities (Lazio Region, 2007). All the data are reported in Appendix B. 2.3. Data analysis The term “macrophyte” is used to refer to all macroscopic aquatic plants, including stoneworts, but excludes filamentous algae, following Lacoul and Freedman (2006). Aquatic plants were split according to their functional groups: emergent species, floating-leaved, submerged and free-floating macrophytes, with the addition of the “charid group” (charophytes) sensu Penning et al. (2008) (Appendix C). The lists of species sampled during the 2010 growing season were compared with historical records (Appendix C) dating from the period 1908–2006. Historical data may be subject to a number of biases (Appendix A). The floristic data collected during the zoobenthos investigations were based on a low number of sampling sites in Albano (1949) and Nemi (2002); almost all the data available were collected using the phytosociological method (Braun-Blanquet, 1964), which cannot be validated using approaches such as resampling procedures (Gotelli and Colwell, 2010); this method, however, can be compared with a phytolittoral inventory, which is considered to be the best means of evaluating species richness in aquatic ecosystems (Kanninen et al., 2013). Furthermore, a detailed dichotomous key for stonewort determination has been available in Italy only since 2009. Consequently, the analysis of aquatic plants was previously conducted only on the vascular plant, leading to the exclusion of stoneworts or to their referral at the genus level, as occurred in Vico (1987) and Nemi (1981). By contrast, historical data on aquatic phanerogams (i.e. those in the upper layers of water ranging from 0 to 4 m of depth) may be considered to be highly reliable as they were based mainly on phytolittoral inventories. Because of the different methods used in the earlier surveys, we used only presence/absence data for our historical comparisons. Caution should be furthermore exercised for the oldest data, as surveys were carried out at largely irregular time intervals; indeed, the majority of the historical surveys date from 1986 to 1998 (Appendix A). 3. Results The surveys conducted during the summer of 2010 led to the detection of 49 different taxa belonging to five different functional groups: emergent species (16), free-floating (2), submerged and floating-leaved macrophytes (16 and 4 taxa, respectively), and charophytes (11) (Appendix C). Emergent species were represented mainly by Phragmites australis (Cav.) Trin. ex Steud. s.l. and Schoenoplectus lacustris (L.) Palla, two species that are restricted to shallow waters (not exceeding ∼2.5 m in depth). The most common free-floating plant species was Ceratophyllum demersum L.; moreover, Myriophyllum spicatum L., Potamogeton pectinatus L., P. lucens L. and Najas marina L. subsp. marina dominated the submerged aquatic vegetation. The presence of floating-leaved macrophytes was instead generally scarce. Nymphaea alba L. and Potamogeton nodosus Poir. alone were recorded in at least two different lakes at the same time. The number of stoneworts was high, with those identified accounting for approximately 30% of the overall number of stoneworts recorded in Italy (Bazzichelli and Abdelahad,

2009). Chara globularis Thuill. was the most widespread species, followed by Chara aspera Deth. ex Wild. and C. vulgaris L. However, well-developed Chara beds were only observed in Bolsena and Vico. Lastly, three alien vascular species were identified: Nelumbo nucifera Gaertn. in Nemi, and Elodea canadensis Michx. and Paspalum distichum L. in Bolsena. With regard to the spatial arrangement of aquatic plant species, the data we collected reveal recurring patterns in floristic assemblages comprising three distinct facies: (a) marginal emergent-macrophyte belts (from the shore down to a depth of 1–2 m) dominated by P. australis s.l., (b) mats of submerged macrophytes in the first few meters (down to 4 m) characterized by the widespread presence of M. spicatum, P. pectinatus and Potamogeton perfoliatus L. cohabiting with C. aspera meadows, and (c) welldeveloped submerged meadows of stoneworts (Chara tomentosa L., C. polyacantha A. Br., and C. globularis) in deep waters down to the maximum depth of macrophyte colonization (Zc ). No distinct pattern in aquatic species emerged when we compared current data with the historical data (Table 2). However, two main tendencies did emerge: (i) a marked decrease in species richness was detected in Lago Grande and Lago Piccolo, with a maximum loss of 16 taxa in the period from 1908 to 2010 in Lago Grande, whereas Vico was characterized by a decline in species richness in more recent years (from 2006 to 2010); (ii) an increase in species richness in Nemi and Bolsena (up to 25 new species identified in Bolsena in 2010 if compared with 1968). On the other hand, even if the lacustrine flora of Albano displayed a relative degree of stability since the mid 1980s, in the twenty years preceding 1980 an increase in species number was reported because of the incompleteness of the previous floristic surveys. Several local plant extinctions, however, are worth mentioning, Lemna minor L. and N. alba in the years following the 1960s and E. canadensis, P. perfoliatus, Nitella gracilis (Sm.) Ag. and Typha angustifolia L. in the years following the 1980s, accompanied by the complete regression of the aquatic vegetation. More specifically, a general decrease occurred in the number of emergent species (by three species in Lago Grande and Lago Piccolo, and a maximum loss of 8 species in Vico) and hydrophytes (by as many as 12 species in Lago Grande), with submerged macrophytes making the most significant contribution to this decrease with 9 species less in Lago Grande. By contrast an increase in charophyte species richness was observed over time, with a maximum increase of 7 charophyte taxa in Bolsena (between 1968 and 2010). The maximum growing depth of macrophytes decreased exclusively in Vico and Lago Grande (−1.5 m and −2.7 m, respectively), whilst an increase was detected in Bolsena, which displayed an average increase of about 8 m in Zc from 1968 to 2010 (Table 2). In keeping with the floristic changes detected, recent years witnessed a substantial improvement in the quality status of waters owing to the progress made in wastewater treatment despite the constant increase in the number of inhabitants at the catchment level and the partial replacement of traditional agriculture practices with more intensive practices. The lakes investigated in this study generally have catchments areas that are largely occupied by natural areas (from 72% to 99%), with the exception of Bolsena and Vico, where the orchard areas account for approximately 15% and 17% of the overall catchment areas, respectively (Appendix B). Moreover, three of the six lakes (Albano, Bolsena and Nemi) have been affected by a drop in water levels, which is most marked in Albano (−4.9 m). With regard to the trophic status of the waters, all the lakes with the exception of Lago Grande and Vico displayed a progressive improvement in recent years, after achieving eutrophic or nearly eutrophic conditions between the 1970s and 1990s. This recent recovery in the water quality of the lakes has been due above all to the progress made in wastewater treatment procedures and the construction of a sewer system at Albano and Bolsena.

25 10.5

3 8 1 2 11 10

2010

45

4. Discussion and conclusions

30 12.0 30 – 17 8.9 10 8.0 9 4.0 6 6.2 7 – 15 4.0 8 3.3 16 – 24 6.0 25 12.0 9 10.0 Total Number Species Zc

18 8.0

15 11.0

9 12.0

34 20.0

6 7 5 3 15 9 11 11 5 3 19 – 5 7 2 1 10 2 0 7 1 1 9 1 3 4 1 1 6 0 2 2 1 1 4 0 2 3 1 1 5 0 5 7 2 1 10 0 6 0 1 1 2 0 10 3 2 1 6 0 9 9 4 1 14 1 6 14 1 2 17 11 3 12 3 2 17 5 2 2 0 1 3 4 2 9 0 1 8 3 3 12 0 1 13 2 2 3 1 2 6 1

1986–87 2010 2001–02 1981 1951 Time-lag

1986–1987

2010

1968

1988

2010

1908

1999

2010

1908

1999

2010

Nemi Lago Piccolo Lago Grande Bolsena Albano

Macro Growth Form Es Sh FLh FFh Hy Ch

Vico

2006

4.1. Aquatic plant species richness

Lake

Table 2 Changes in aquatic species richness within the Italian volcanic-lake system; we show variations in the occurrence of lacustrine flora and the maximum depth of macrophyte colonization (Zc ). Floristic data were splitted into five categories: Es = emergent species, Hy = hydrophytes plant (separated into Sh = submerged macrophytes, FLh = floating-leaved macrophytes and FFh = free-floating macrophytes), and Ch = charids.

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There has been a major change in the composition of the aquatic flora within the Italian volcanic-lake system: the regional plant species richness recorded in 2010 (49 taxa) differs considerably to the total number of aquatic taxa recorded over the last century (63 taxa) (Appendix C). Emergent species and submerged macrophytes are the two most common functional groups (both 16 taxa), though stoneworts also contribute significantly to local submerged plant species richness (11 taxa), accounting for a considerable percentage of the Italian and European stonewort species richness (30% and 20%, respectively) (Krause, 1997; Bazzichelli and Abdelahad, 2009). These findings led to the inclusion of this lake system in the Italian Important Plant Areas (IPA; Blasi et al., 2011). In general, the introduction of alien species did not influence this result; indeed, despite the growing presence of alien species in the Italian volcanic-lake system (Celesti-Grapow et al., 2010; Pretto et al., 2010), the percentage of non-native taxa detected in our study was extremely low (3). The greatest species loss was observed for floating-leaved and free-floating macrophytes (50% of the total number of recorded species), while the emergent species dropped by 25%. However, in absolute numbers, the functional groups that had suffered the greatest loss were the emergent species and submerged macrophytes, with 5 taxa each (Appendix C). This is not surprising, as land use adjacent to a lake, and especially in the areas closest to the lake’s shoreline, appears to be a major factor influencing aquatic plant richness – as reported by Dodson (2008) and Alahunta et al. (2012) – together with the nutrient availability (Lacoul and Freedman, 2006 and references therein). Over the last century, the six lakes considered exhibited a general progressive watershed “development” sensu Hoffman and Dodson (2005) (e.g. agricultural, residential and urban) that mainly affected littoral and shores of water basins (Appendix B). Furthermore, the littoral zone responds to external disturbances earlier than pelagic one (Lambert et al., 2008; Lambert and Cattaneo, 2009). As a result, the emergent species are widely endangered at local scale. Similarly, several authors (Lombardo, 2005; Sand-Jensen et al., 2008) stressed on the correlation between the presence of hydrophytes and Secchi disk as a proxy of lake metabolism supporting the evidence that submerged macrophytes are the most threatened aquatic plant functional group under eutrophication as occurred in the present paper (Riis and Sand-Jensen, 2001; Bolpagni et al., 2013a). 4.2. Aquatic plant species temporal patterns The present study reveals the existence of two main temporal patterns. The first highlights a marked decrease in macrophyte numbers in the long term, as observed in Lago Grande and Lago Piccolo, while the second points to a considerable increase in species richness in the short-term (i.e. from the mid 1980s to 2010, as observed in Bolsena and Nemi). These results are consistent with trends observed in similar studies that have compared current data with the species richness levels typical of pre-mechanical agricultural times (between the late 19th century and World War II), which have highlighted marked reductions in aquatic plant richness in lowland, overexploited, lentic aquatic environments, associated with habitat loss followed by a partial recovery of aquatic plant occurrence in recent decades (since the late 1970s) (Sand-Jensen et al., 2008). In other words, the observed trends in aquatic plant richness confirm that changes in human pressures over time and space (e.g. watershed development and land-use transformation), which have led to a marked improvement in water quality (e.g. water

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transparency and nutrient control) and a progressive deterioration in shorelines and lacustrine ecotones, are strongly related to the decline in biodiversity and species composition of lake communities (Dodson, 2008; Alahunta et al., 2012). As expected, the highest aquatic plant loss rates were recorded (i) along the marginal lacustrine habitats and in the first meters of depth, and (ii) for submerged macrophytes. Indeed, significant reductions in macrophyte richness were observed in lakes without efficient wastewater treatment facilities (Lago Grande, Lago Piccolo and Vico). By contrast, a marked recovery in aquatic plant richness (especially charophytes) characterized the lakes where water trophic conditions and transparency have increased significantly since the mid 1980s (Bolsena and Nemi). Moreover, in lakes characterized by a recent increase in Zc (Albano, Nemi, and Bolsena), efficient sewer systems installed in recent decades have had a highly positive effect on water transparency and have reduced nutrient availability. On the other hand, we detected a decrease in Zc in lakes whose shorelines are characterized by low levels of urbanization but lack efficient sewer systems (Vico and Lago Grande). 5. Conclusions Our study presents the first systematic characterization and review of macrophyte species richness and changes in temporal patterns in the Italian volcanic-lake system. The results of this study highlight (i) the presence of a considerable degree of regional aquatic plant species richness and (ii) a marked number of stoneworts species. By contrast, over the last century a relevant reduction in species number was recorded for emergent species and submerged macrophytes due to a progressive deterioration of littorals, a rather diffuse lake catchment artificialization and an incomplete water-quality recovery. As pointed out by Sax and Gaines (2003), the effects of stress on plant species richness can only be effectively assessed by means of repeated surveys at different times. Unfortunately, very few studies designed to provide long-term floristic composition data have been conducted, than we have no indication about pristine condition. The present study seeks to fill the gaps in the knowledge of macrophyte species richness in the most important freshwater inland lake system in the Mediterranean region, but much more can be done, for example looking at other possible ways to find information about the past conditions (Garcia, 1994; Bennion et al., 2011). Acknowledgements We would like to thank the referees for their valuable suggestions and Lewis Baker for revising the English manuscript. A special thanks to Giuseppe Morabito and Caridad de Hoyos for providing the data on natural lakes in the Mediterranean GIG. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.aquabot.2013.07.005. References Alahunta, J., Kanninen, A., Vuori, K.-M., 2012. Response of macrophyte communities and status metrics to natural gradients and land use in boreal lakes. Aquat. Bot. 103, 106–114. Almquist, E., 1929. Upplands vegetation och flora. Acta Phytogeogr. Suec. 1, 1–624. Avena, G., Scoppola, A., 1987. Caratteristiche dei complessi ad idrofite ed elofite. In: Carunchio, V. (Ed.), Valutazione della situazione ambientale del Lago di Nemi. Università degli Studi di Roma “La Sapienza”. e Provincia di Roma, Roma, p. 75. Azzella, M.M., Rosati, L., Iberite, M., Blasi, C., 2012. Short database report. In: Den´ M., Ewald, J., Finckh, M., Glöckler, F., gler, J., Oldeland, J., Jansen, F., Chytry,

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