A multibiomarker study to delineate the effects of environmental stressors on aquatic shellfishes of West Bengal

Abstract

Over the past decade a great attention has been paid to decipher the consequences of impending climate change scenario on the physiological and biochemical functioning of aquatic organisms. Anthropogenic activities primarily combustion of fossil fuel is the prime cause behind the increased concentration of CO2 into the atmosphere. As a consequence, marine environments are anticipated to experience more shift towards lower pH (ocean acidification) and elevated temperatures (ocean warming). Global climate change induced ocean warming and acidification have complex reverberation on physiological functioning of marine ectotherms. Moreover, since the industrial revolution the growing demand for petroleum-based products has been mounting up worldwide leading to severe oil pollution. Widespread use of pesticides in modern agricultural system has a significant contribution in polluting aquatic habitats across the world; and enclosed freshwater ecosystem being the ultimate receptacle is at great risk. In recent years, application of nanotechnology also has become more widespread and nanomaterials are constantly being released into aquatic environments and posing a potential risk to various organisms and ecosystems. Research works merging climate change stressors and incipient chemical pollutants are imperative to better comprehend and interpret biological effects in altering aquatic habitat. Environmental factors and pollution generally do not act in isolation, but usually perform collectively. Several researches have recognized the discrete effects of these drivers on species and ecosystems separately but studies regarding the interactive effects of multiple drivers are scarce. Animal physiologists have now unambiguously recognized the fact that anticipated climatic vicissitudes will impose noteworthy consequences on physiological functioning of most species. Ectotherms are of specific interest as their physiology principally relies on the external environment. The purpose of present study was to compare and decipher the impacts of multiple stressors and specifically whether global environmental drivers aggravate the effects of a local driver (pollution) on physiological energetics and antioxidant responses of two economically significant shellfishes from West Bengal. Two species from two different ecosystems- freshwater and estuarine were studied to compare and decode the ecological functioning of these realms distinctly. Multiple biomarkers from different levels of biological strata (physiological energetics, energy budget, thermal performance, antioxidant and detoxification defence mechanisms, lipid peroxidation levels, DNA damage) of the species were evaluated to understand responses. Stress levels were amalgamated from individual biomarker responses using an “Integrated Biomarker Response (IBR)” approach. The present doctoral work can provide an outline for more integrated management of commercially exploited shellfish populations, and shed light into coastal fisheries and aquaculture prospects in the impending future.