Loading...
Publication
Characterisation of physiological conditions and evaluation of well-being in two species of bivalve molluscs (Ruditapes philippinarum and Chamelea gallina) intensively exploited in coastal and lagoon areas of the Northern Adriatic Sea (Italy)
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 1.19 MB | Adobe PDF |
Authors
Abstract(s)
Ruditapes philippinarum e Chamelea gallinasão duas espécies de bivalves comuns na infauna dos sedimentos arenosos e areno-vasosos da zona Norte do Mar Adriático, mas adaptados a diferentes ambientes, ocorrendo a primeira espécie na lagoa de Veneza e a segunda, na zona costeira. Ambas as espécies constituem recursos económicos importantes para as pescas nessa área geográfica, consequentemente sendo alvos de pesca intensiva. Com o objectivo de caracterizar as respostas fisiológicas básicas de C. gallinae R. philippinarum, na primeira parte deste trabalho efectuaram-se várias determinações de parâmetros da fisiologia e bioquímica das espécies em estudo. As medições dos parâmetros fisiológicos efectuados em R. philippinarumde um modo geral não evidenciaram uma variação estacional típica, confirmando a tolerância elevada da espécie face às alterações das condições ambientais. A taxa de filtração de C. gallinaaumentou ligeiramente com o aumento da temperatura da água e com valores mais constantes da taxa de respiração. Na segunda parte do estudo, analisaram-se os efeitos de curto-prazo e longo-prazo resultantes do stress causado pela actividade da pesca, para as duas espécies. Os parâmetros fisiológicos medidos em R. philippinarumevidenciaram o melhor estado dos bivalves usados no controlo e encontraram-se também diferenças entre os níveis de carbohidratos e glicogénio entre bivalves da zona pescada e não pescada. Relativamente a C. gallina, as taxas fisiológicas e a sobrevivência ao ar foram aparentemente mais influenciadas pelo impacto da draga hidráulica: a filtração e crescimento potencial evidenciaram uma tendência para valores menores à medida que o stress mecânico aumentou nos dois locais.
Por último, verificou-se que a pressão da água e a triagem mecânica aumentaram significativamente os danos nas conchas de C. gallina, que atingem os valores mais elevados verificados nas pescas comerciais com dragas.
Ruditapes philippinarum and Chamelea gallina are infaunal bivalves widespread in sandy and sandy-silty bottoms along the Northern Adriatic Sea but adapted to different environments, the former being distributed in the Lagoon of Venice, the latter along the marine coastline. Bothspecies represent important economic resources for fisheries in this area, consequently suffering intense fishing pressure. With the aim of characterising the basic physiological responses of C. gallina and R. philippinarum, in the first part of the present study a series of physiological determinations and biochemical measurements have been performed. Physiological measurements on R. philippinarum generally did not show clear seasonal trends, thus confirming the great tolerance of this species to changing environmental conditions. C. gallina exhibited slight increase in clearance rate at the highest water temperature and more constant values in respiration rate. In the second part of the research, possible fishing-induced stress experienced by the two clam species has been studied in terms of both short- and long-term effects. Physiological parameters detected on R. philippinarumgenerally highlighted the better state of health of the control organisms, and some differences have been recorded also comparingtotal carbohydrates and glycogen in samples from fishing and non-fishing area. As for C. gallina, physiological rates and survival in air test seemed to be more influenced by the impact of the hydraulic dredging: clearance and scope for growth generally showed decreasing trends as mechanical stress increased in both sampling sites. Lastly, the water pressure and the mechanised sorting significantly increased the shell damage on C. gallina specimens, the highest levels always being observed in commercially dredged clams.
Ruditapes philippinarum and Chamelea gallina are infaunal bivalves widespread in sandy and sandy-silty bottoms along the Northern Adriatic Sea but adapted to different environments, the former being distributed in the Lagoon of Venice, the latter along the marine coastline. Bothspecies represent important economic resources for fisheries in this area, consequently suffering intense fishing pressure. With the aim of characterising the basic physiological responses of C. gallina and R. philippinarum, in the first part of the present study a series of physiological determinations and biochemical measurements have been performed. Physiological measurements on R. philippinarum generally did not show clear seasonal trends, thus confirming the great tolerance of this species to changing environmental conditions. C. gallina exhibited slight increase in clearance rate at the highest water temperature and more constant values in respiration rate. In the second part of the research, possible fishing-induced stress experienced by the two clam species has been studied in terms of both short- and long-term effects. Physiological parameters detected on R. philippinarumgenerally highlighted the better state of health of the control organisms, and some differences have been recorded also comparingtotal carbohydrates and glycogen in samples from fishing and non-fishing area. As for C. gallina, physiological rates and survival in air test seemed to be more influenced by the impact of the hydraulic dredging: clearance and scope for growth generally showed decreasing trends as mechanical stress increased in both sampling sites. Lastly, the water pressure and the mechanised sorting significantly increased the shell damage on C. gallina specimens, the highest levels always being observed in commercially dredged clams.
Description
Tese de Doutoramento, Ecologia, Especialidade de Ecofisiologia, Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, 2007
Keywords
Ecofisiologia Chamelea gallina Ruditapes philippinarum Bioquímica