牡蛎壳粉对沉积环境及两种底栖动物生长和生理的影响OA

Sediment acidification and sulfide accumulation pose critical threats to the long-term sustainability of intensive marine aquaculture systems.Excess uneaten feed and benthic fecal deposits enrich sediment organic matter,drive the rapid depletion of bottom-water dissolved oxygen,and subsequently stimulate microbial sulfate reduction,leading to the buildup of toxic hydrogen sulfide(H2S)in anoxic sediments.These coupled biogeochemical processes exert severe adverse impacts on benthic faunal health and the operational stability of coastal aquaculture,making the development of targeted,cost-effective sediment quality improvement strategies a core priority for sustainable aquaculture management.While raw oyster shell powder is a widely applied calcium-based amendment for aquatic environmental remediation,the comparative performance of raw and thermally calcined oyster shell powder in modifying marine sediment geochemistry and influencing zoobenthos remains poorly documented.To systematically assess their remediation potential and associated ecological effects,a 60-day controlled mesocosm experiment was conducted in recirculating seawater aquarium systems.Sediment substrates were amended with two treatments:10%(w/w)raw oyster shell powder(raw treatment)and 5%(w/w)calcined oyster shell powder(calcined treatment),with unamended sediment serving as the control.Two ecologically and economically important benthic species,the polychaete Perinereis aibuhitensis and the Manila clam Ruditapes philippinarum,were selected as test organisms.Pore water samples were collected at 20-day intervals to quantify pH and dissolved H2S concentrations,while the growth performance,survival rate,and key antioxidant enzyme activities(total antioxidant capacity,T-AOC;catalase,CAT;superoxide dismutase,SOD)of both species were measured at the end of the experiment.The results demonstrated that both amendments significantly elevated sediment pore water pH and reduced H2S concentrations relative to the control(P<0.05).Pore water pH increased by approximately 0.5 units in the raw treatment and 1.6 units in the calcined treatment,while H2S concentrations decreased by 60.0%and 74.3%,respectively.Although pore water pH in the calcined treatment exhibited a gradual declining trend in the late experimental stage,it remained significantly higher than both the control and raw treatment groups(P<0.001).The raw amendment significantly promoted the growth of both benthic species:the body weight of P.aibuhitensis was 14.59%higher than the control,while the shell height,shell length,shell width,and whole soft tissue weight of R.philippinarum increased by 9.30%,7.59%,12.35%,and 18.31%,respectively.No significant difference in survival rate was observed between the raw treatment and the control(P>0.05).In contrast,the calcined treatment resulted in significantly reduced survival for both species(P<0.01),accompanied by a general upregulation of antioxidant enzyme activities.Notably,CAT activity in R.philippinarum under the calcined treatment was 63.8%higher than that in the raw treatment(P<0.05).The two species exhibited distinct response patterns to modified sediment conditions:the sessile,buried clam showed more pronounced physiological fluctuations under substrate stress,whereas the burrow-constructing polychaete maintained relatively stable sediment redox conditions and antioxidant enzyme levels.This interspecific difference is likely attributed to the bioturbation behavior of P.aibuhitensis,which actively constructs and irrigates burrows to enhance pore water flushing and mitigate localized environmental stress,conferring higher overall stress tolerance compared to R.philippinarum.Calcined oyster shell powder achieved faster sediment quality improvement due to its high inherent alkalinity and chemical reactivity,but the resultant excessive sediment alkalization induced severe oxidative stress and reduced benthic organism survival.In comparison,raw oyster shell powder provided a milder,long-lasting remediation effect that supported superior growth and survival for both test species.Considering both ecological safety and aquaculture production benefits,raw oyster shell powder is more suitable for practical application as a sediment conditioner in marine aquaculture ponds.The field application of calcined oyster shell powder,however,requires careful pre-assessment of application dosage to avoid potential ecological risks associated with excessive sediment alkalization.