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Incidence of spinal deformities in natural populations of sandsmelt, Atherina boyeri (Risso, 1810) in the Neretva river estuary, middle Adriatic
Fisheries Research 45 (2000) 61±64
Short communication
Incidence of spinal deformities in natural populations of sandsmelt, Atherina boyeri (Risso, 1810) in the Neretva river estuary, middle Adriatic P. Tutman, B. Glamuzina*, B. Skaramuca, V. KozÏul, N. GlavicÂ, D. LucÏic Laboratory of Ecology and Aquaculture, Institute of Oceanography and Fisheries, PO Box 83, 20 000 Dubrovnik, Croatia Received 27 April 1999; received in revised form 16 August 1999; accepted 23 August 1999
Abstract Information is presented on the occurrence of spinal deformities in natural populations of sandsmelt, Atherina boyeri in the Neretva River estuary, middle eastern Adriatic. During 1998 and 1999, the spinal deformity levels varied between 2.02% and 10.30% in four samplings, and 3.58% in total catch. The spine is deformed in one to a few places from vertical to horizontal angles, and the deformities are visible on the ®sh body immediately after catching. The possible reasons for such deformities are discussed. # 2000 Elsevier Science B.V. All rights reserved. Keywords: Spinal deformities; Sandsmelt; Atherina boyeri
1. Introduction Spinal deformities in natural and reared ®sh populations are relatively well described and many reports have been published on different ®sh species. Presently, this is a signi®cant problem in hatchery-produced ®sh, as it in¯uences the economical success of rearing. The ®ndings of deformed ®sh in the Adriatic are not rare, but they are limited to sporadically caught specimens (Jardas and MorovicÂ, 1973; Jardas and Homen, 1977) and they are not connected to any
*
Corresponding author. Tel.: 385-20-416-971; fax: 385-20425-775. E-mail address: [email protected] (B. Glamuzina).
known cause. The higher frequency of spinal deformities was reported only for red mullet, Mulus barbatus but without detailed analysis (Jardas and MorovicÂ, 1975). If the level of deformities is high and constant and exists in different age classes, it could be a sign of signi®cant ecosystem changes or genetic changes of population. This could in¯uence the ®shery if deformities exist in populations of commercially important species. Sandsmelt, Atherina boyeri (Risso, 1810) (Teleostei; Atherinidae) is an euryhaline species that lives in the brackish waters of estuaries and lagoons of the whole Mediterranean, and sporadically along the coasts of Britain, Holland and the Atlantic coasts of Spain and Morocco (Fischer et al., 1987). In the Adriatic, sandsmelt is frequent along the whole coast.
0165-7836/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 5 - 7 8 3 6 ( 9 9 ) 0 0 0 9 8 - 3
62
P. Tutman et al. / Fisheries Research 45 (2000) 61±64
The main species characteristics are: fast growth, early maturation after the ®rst year, long spawning season and short (3 years) life cycle (Jardas, 1996). It is an important semi-industrial ®sh species in the Adriatic and for artisanal ®shery in the Mediterranean (Fischer et al., 1987) mostly living and reproducing in coastal waters and estuaries during its whole life cycle. It is exposed to many physical and chemical variations, from temperature and salinity changes to pollution, in these most threatened sea ecosystems. This paper describes the spinal deformities found in natural populations of sandsmelt, Atherina boyeri in the Neretva River estuary, in the middle Adriatic.
of the Neretva River, situated on the mid-east Adriatic coast (Fig. 1). Caught ®sh were counted and the percentage of deformation was calculated. They were preserved in 4% formalin. The length (cm) and weight (g) of preserved specimens was measured. Age was determined by scale reading. The condition factor of normal and deformed ®sh was calculated using the formula: IC 100W/l3 (W, weight; l, length) and the difference was calculated using a t-test. The preserved specimens were radiographed using a medical X-ray system and the pictures were used for an examination of the skeleton.
2. Materials and methods
3. Results
Fish were caught with a beach seine net (50 m length, 1±5 m depth) during July and August of 1998 and February and March of 1999 in the estuary
A total of 1479 ®sh was caught and 53 were deformed, which represents 3.58%. The percent of deformed ®sh in separate catches was 2.02% (1137
Fig. 1. Fishing sites: (a) wider area and (b) estuary of the Neretva River.
P. Tutman et al. / Fisheries Research 45 (2000) 61±64
63
statistically signi®cant (P < 0.05). The condition index of normal sandsmelt is 0.61 0.099 (mean standard deviation), and of deformed 0.58 0.092. 4. Discussion
Fig. 2. Deformed sandsmelt, Atherina boyeri caught in the estuary of the river Neretva, middle Adriatic.
specimens catch), 8.10% (111 specimens catch), 8.20% (134 specimens catch) and 10.30% (97 specimens catch). Spinal anomalies were visible on the ®sh body immediately upon catching, with all kinds of deformities, vertically and horizontally (Fig. 2), with the spine curved at one or more places (Fig. 3). The internal body spaces and organs were normally developed, according to X-ray radiographs. Vertebral deformities were noticed, especially at curvation points. The vertebra body (centrum) was considerably thicker than normal, particularly at the ends, and the cartilage rings between were much thicker than normal. There were no visible deformities of the remaining skeletal parts (skull, ®n, tail bones). The spinal deformities occurred in different year classes, 0, 1, 2, but was not found in 3 old ®sh. There is a noticeable slight decrease in the length and condition index of deformed sandsmelt in comparison to those normal, but the difference is not
The appearance of spinal deformities in the different growth stages of sandsmelt in the estuary of the Neretva River suggests the existence of signi®cant disturbances in the ecosystem. Spinal deformities were not noted with the remaining southern Adriatic sandsmelt populations during 1998 and 1999 (Tutman, unpublished data). The fact that spinal deformities appear in 0, 1 and 2 growth categories of sandsmelt suggests that ecosystem disturbances occur every year. The absence of older deformed sandsmelt in the population might be a sign that the disturbances are related to the last 3 years, but it could also be explained by higher mortality of deformed ®sh as compared to normal ®sh. The question remains open as to the causes of sandsmelt deformity in the Neretva River estuary. As this is an important agricultural region that uses high quantities of pesticides and herbicides during spring and summer, i.e. during spawning and early development periods for sandsmelt, contamination by these chemicals might be the cause. On the other hand, the last 3 years have shown an increasing pollution emanating from neighbouring Bosnia and Herzegovina, which coincides with the operation of large metal industries following the 5 year interruption due to war. A wide range of physical, chemical and biological factors may cause spinal deformities of various ®sh species in natural and reared conditions (Chatain, 1994; Haya, 1989; Slooff, 1982; Weiss and Weiss, 1989; Wiegand et al., 1989; etc.). Recent research on seabream, Sparus aurata indicates that most spinal deformities occur during embryonic development, and that the causes could be due to genetic, yolk content, and environmental conditions such as temperature, light, mechanical stress, and pollution, which could affect both parents and embryos (Andrades et al., 1996). For this reason, further research of this phenomenon will concentrate on the spawning and early developmental stages of sandsmelt, but also on the accummulation of pollutants in the gonads of adult specimens.
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P. Tutman et al. / Fisheries Research 45 (2000) 61±64
Fig. 3. X-ray radiographs of deformed spines of sandsmelt. Spines of the three normal specimens are marked (X).
Acknowledgements We are grateful to Dr. Ivan Katavic, Dr. Miroslav Kraljevic and Dr. Jakov Dulcic for their contribution to the ®rst sampling of deformed sandsmelt. References Andrades, J.A., Becerra, J., Fernandez Llebrez, P., 1996. Skeletal deformities in larval, juvenile and adult stages of cultured gilthead sea bream (Sparus aurata L.). Aquaculture 141, 1±11. Chatain, B., 1994. Abnormal swimbladder development and lordosis in sea bass (Dicentrarchus labrax) and sea bream (Sparus auratus). Aquaculture 119, 371±379. Fischer, W., Bauchot, M.L., Schneider, M., 1987. Fiches FAO d'identification des espeÂces pour les besoins de la peÂche. (ReÂvision 1). MeÂditerraneÂe et mer Noire. Zone de peÂche 37, vol. II. Rome, FAO, vol. 2, pp. 761±1530.
Haya, K., 1989. Toxicity of pyrethroid insecticides to fish. Environ. Toxicol. Chem. 8, 381±391. Jardas, I., MorovicÂ, D., 1973. Contribution a la connaissance des exemplaires teÂratologiques des poissons Adriatiques. BiljesÏke-Notes, Institut of Oceanography and Fisheries, Split. No. 31. Jardas, I., MorovicÂ, D., 1975. TeratolosÏki primjerci riba u Jadranu. Pomorski zbornik 13, 511±528. Jardas, I., Homen, Z., 1977. Nouvelles trouvailles sur les anomalies anatomiques des poissons Adriatiques. BiljesÏke-Notes, Institut of Oceanography and Fisheries, Split. No. 34. Jardas, I., 1996. Jadranska ihtiofauna. SÏkolska knjiga. Zagreb, p. 533. Slooff, W., 1982. Skeletal anomalies in fish from polluted surface waters. Aquatic toxicology 2, 157±173. Weiss, J.S., Weiss, P., 1989. Effects of environmental pollutants on early fish development. Aquat. Sci. 1, 45±73. Wiegand, M.D., Hataley, J.M., Kitchen, C.L., Buchanan, L.G., 1989. Induction of developmental abnormalities in larval goldfish, Carassius auratus L., under cool incubation conditions. J. Fish Biol. 35, 85±95.
Short communication
Incidence of spinal deformities in natural populations of sandsmelt, Atherina boyeri (Risso, 1810) in the Neretva river estuary, middle Adriatic P. Tutman, B. Glamuzina*, B. Skaramuca, V. KozÏul, N. GlavicÂ, D. LucÏic Laboratory of Ecology and Aquaculture, Institute of Oceanography and Fisheries, PO Box 83, 20 000 Dubrovnik, Croatia Received 27 April 1999; received in revised form 16 August 1999; accepted 23 August 1999
Abstract Information is presented on the occurrence of spinal deformities in natural populations of sandsmelt, Atherina boyeri in the Neretva River estuary, middle eastern Adriatic. During 1998 and 1999, the spinal deformity levels varied between 2.02% and 10.30% in four samplings, and 3.58% in total catch. The spine is deformed in one to a few places from vertical to horizontal angles, and the deformities are visible on the ®sh body immediately after catching. The possible reasons for such deformities are discussed. # 2000 Elsevier Science B.V. All rights reserved. Keywords: Spinal deformities; Sandsmelt; Atherina boyeri
1. Introduction Spinal deformities in natural and reared ®sh populations are relatively well described and many reports have been published on different ®sh species. Presently, this is a signi®cant problem in hatchery-produced ®sh, as it in¯uences the economical success of rearing. The ®ndings of deformed ®sh in the Adriatic are not rare, but they are limited to sporadically caught specimens (Jardas and MorovicÂ, 1973; Jardas and Homen, 1977) and they are not connected to any
*
Corresponding author. Tel.: 385-20-416-971; fax: 385-20425-775. E-mail address: [email protected] (B. Glamuzina).
known cause. The higher frequency of spinal deformities was reported only for red mullet, Mulus barbatus but without detailed analysis (Jardas and MorovicÂ, 1975). If the level of deformities is high and constant and exists in different age classes, it could be a sign of signi®cant ecosystem changes or genetic changes of population. This could in¯uence the ®shery if deformities exist in populations of commercially important species. Sandsmelt, Atherina boyeri (Risso, 1810) (Teleostei; Atherinidae) is an euryhaline species that lives in the brackish waters of estuaries and lagoons of the whole Mediterranean, and sporadically along the coasts of Britain, Holland and the Atlantic coasts of Spain and Morocco (Fischer et al., 1987). In the Adriatic, sandsmelt is frequent along the whole coast.
0165-7836/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 5 - 7 8 3 6 ( 9 9 ) 0 0 0 9 8 - 3
62
P. Tutman et al. / Fisheries Research 45 (2000) 61±64
The main species characteristics are: fast growth, early maturation after the ®rst year, long spawning season and short (3 years) life cycle (Jardas, 1996). It is an important semi-industrial ®sh species in the Adriatic and for artisanal ®shery in the Mediterranean (Fischer et al., 1987) mostly living and reproducing in coastal waters and estuaries during its whole life cycle. It is exposed to many physical and chemical variations, from temperature and salinity changes to pollution, in these most threatened sea ecosystems. This paper describes the spinal deformities found in natural populations of sandsmelt, Atherina boyeri in the Neretva River estuary, in the middle Adriatic.
of the Neretva River, situated on the mid-east Adriatic coast (Fig. 1). Caught ®sh were counted and the percentage of deformation was calculated. They were preserved in 4% formalin. The length (cm) and weight (g) of preserved specimens was measured. Age was determined by scale reading. The condition factor of normal and deformed ®sh was calculated using the formula: IC 100W/l3 (W, weight; l, length) and the difference was calculated using a t-test. The preserved specimens were radiographed using a medical X-ray system and the pictures were used for an examination of the skeleton.
2. Materials and methods
3. Results
Fish were caught with a beach seine net (50 m length, 1±5 m depth) during July and August of 1998 and February and March of 1999 in the estuary
A total of 1479 ®sh was caught and 53 were deformed, which represents 3.58%. The percent of deformed ®sh in separate catches was 2.02% (1137
Fig. 1. Fishing sites: (a) wider area and (b) estuary of the Neretva River.
P. Tutman et al. / Fisheries Research 45 (2000) 61±64
63
statistically signi®cant (P < 0.05). The condition index of normal sandsmelt is 0.61 0.099 (mean standard deviation), and of deformed 0.58 0.092. 4. Discussion
Fig. 2. Deformed sandsmelt, Atherina boyeri caught in the estuary of the river Neretva, middle Adriatic.
specimens catch), 8.10% (111 specimens catch), 8.20% (134 specimens catch) and 10.30% (97 specimens catch). Spinal anomalies were visible on the ®sh body immediately upon catching, with all kinds of deformities, vertically and horizontally (Fig. 2), with the spine curved at one or more places (Fig. 3). The internal body spaces and organs were normally developed, according to X-ray radiographs. Vertebral deformities were noticed, especially at curvation points. The vertebra body (centrum) was considerably thicker than normal, particularly at the ends, and the cartilage rings between were much thicker than normal. There were no visible deformities of the remaining skeletal parts (skull, ®n, tail bones). The spinal deformities occurred in different year classes, 0, 1, 2, but was not found in 3 old ®sh. There is a noticeable slight decrease in the length and condition index of deformed sandsmelt in comparison to those normal, but the difference is not
The appearance of spinal deformities in the different growth stages of sandsmelt in the estuary of the Neretva River suggests the existence of signi®cant disturbances in the ecosystem. Spinal deformities were not noted with the remaining southern Adriatic sandsmelt populations during 1998 and 1999 (Tutman, unpublished data). The fact that spinal deformities appear in 0, 1 and 2 growth categories of sandsmelt suggests that ecosystem disturbances occur every year. The absence of older deformed sandsmelt in the population might be a sign that the disturbances are related to the last 3 years, but it could also be explained by higher mortality of deformed ®sh as compared to normal ®sh. The question remains open as to the causes of sandsmelt deformity in the Neretva River estuary. As this is an important agricultural region that uses high quantities of pesticides and herbicides during spring and summer, i.e. during spawning and early development periods for sandsmelt, contamination by these chemicals might be the cause. On the other hand, the last 3 years have shown an increasing pollution emanating from neighbouring Bosnia and Herzegovina, which coincides with the operation of large metal industries following the 5 year interruption due to war. A wide range of physical, chemical and biological factors may cause spinal deformities of various ®sh species in natural and reared conditions (Chatain, 1994; Haya, 1989; Slooff, 1982; Weiss and Weiss, 1989; Wiegand et al., 1989; etc.). Recent research on seabream, Sparus aurata indicates that most spinal deformities occur during embryonic development, and that the causes could be due to genetic, yolk content, and environmental conditions such as temperature, light, mechanical stress, and pollution, which could affect both parents and embryos (Andrades et al., 1996). For this reason, further research of this phenomenon will concentrate on the spawning and early developmental stages of sandsmelt, but also on the accummulation of pollutants in the gonads of adult specimens.
64
P. Tutman et al. / Fisheries Research 45 (2000) 61±64
Fig. 3. X-ray radiographs of deformed spines of sandsmelt. Spines of the three normal specimens are marked (X).
Acknowledgements We are grateful to Dr. Ivan Katavic, Dr. Miroslav Kraljevic and Dr. Jakov Dulcic for their contribution to the ®rst sampling of deformed sandsmelt. References Andrades, J.A., Becerra, J., Fernandez Llebrez, P., 1996. Skeletal deformities in larval, juvenile and adult stages of cultured gilthead sea bream (Sparus aurata L.). Aquaculture 141, 1±11. Chatain, B., 1994. Abnormal swimbladder development and lordosis in sea bass (Dicentrarchus labrax) and sea bream (Sparus auratus). Aquaculture 119, 371±379. Fischer, W., Bauchot, M.L., Schneider, M., 1987. Fiches FAO d'identification des espeÂces pour les besoins de la peÂche. (ReÂvision 1). MeÂditerraneÂe et mer Noire. Zone de peÂche 37, vol. II. Rome, FAO, vol. 2, pp. 761±1530.
Haya, K., 1989. Toxicity of pyrethroid insecticides to fish. Environ. Toxicol. Chem. 8, 381±391. Jardas, I., MorovicÂ, D., 1973. Contribution a la connaissance des exemplaires teÂratologiques des poissons Adriatiques. BiljesÏke-Notes, Institut of Oceanography and Fisheries, Split. No. 31. Jardas, I., MorovicÂ, D., 1975. TeratolosÏki primjerci riba u Jadranu. Pomorski zbornik 13, 511±528. Jardas, I., Homen, Z., 1977. Nouvelles trouvailles sur les anomalies anatomiques des poissons Adriatiques. BiljesÏke-Notes, Institut of Oceanography and Fisheries, Split. No. 34. Jardas, I., 1996. Jadranska ihtiofauna. SÏkolska knjiga. Zagreb, p. 533. Slooff, W., 1982. Skeletal anomalies in fish from polluted surface waters. Aquatic toxicology 2, 157±173. Weiss, J.S., Weiss, P., 1989. Effects of environmental pollutants on early fish development. Aquat. Sci. 1, 45±73. Wiegand, M.D., Hataley, J.M., Kitchen, C.L., Buchanan, L.G., 1989. Induction of developmental abnormalities in larval goldfish, Carassius auratus L., under cool incubation conditions. J. Fish Biol. 35, 85±95.