Department of Life Sciences

Permanent URI for this collection

http://presiuniv.ndl.gov.in:4009/handle/123456789/2326

Browse

Browsing Department of Life Sciences by Author "Mandal, Sumit"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    A multibiomarker study to delineate the effects of environmental stressors on aquatic shellfishes of West Bengal
    Mandal, Sumit
    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.
  • No Thumbnail Available
    Item
    Studies on Ecology of Soft-Bottom Meiobenthic Community from Sundarban Estuarine System, West Bengal, India
    Mandal, Sumit
    Structure of meiobenthic assemblage was assessed for the first time from world’s largest mangrove ecosystem, Sundarbans, focusing on free living nematode species composition (~ 90% of the total population). The present research revealed the deleterious effect of excessive monsoonal rain on meiobenthos as well as free-living nematode assemblages. Abundance of meiobenthos declined from early monsoon to later period of monsoon due to massive riverine runoff followed by cloudburst phenomenon that completely flushed the estuary. Significant temporal and spatial heterogeneity in the abundance of meiobenthos and nematode species composition was also described in relation with environmental variables. Distinct seasonal fluctuation of meiobenthos was prominent due to seasonal changes in sedimentary environment. Nematodes dominated the meiobenthic assemblages, ranking harpacticoid copepod in the second position. Altogether, 79 species of free-living nematode had been identified for the first time and nematode assemblage was dominated by Sabatieria preadatrix, Sphaerolaimus bulticus, Desmodora communis, Dorylaimopsis punctata and Daptonema hirsutum. Biological trait approach of nematode assemblages was applied to investigate the ecological functioning based on morphological and ecological characteristics, which added relevant information regarding relationships between species diversity and the abiotic environment. Furthermore, present study conducted a pioneering survey regarding vertical stratification of meiobenthic assemblages in different mangrove vegetation with nematofaunal species level information. This study clearly depicted that more than 90% of faunal populations was concentrated within upper 3-4 cm of sediment, though they were present up to 15 cm of depth. Furthermore, combined effect of climate change mediated elevated temperature and petroleum pollution on meiobenthic organisms were also investigated through a benthocosm experiment. The present research highlighted harmful effects of these stressors on meiobenthic species composition and abundance. Present observation would be a maiden footstep to understand the resilience of meiobenthic organisms to predicted climate change scenarios. Altogether the present thesis provided blended information about the succession pattern of meiobenthic community structure along with environmental parameters and illustrated the detrimental effect of climate change and anthropogenic perturbation on meiobenthos from Sundarbans. This overview represents a first step to implement a baseline data that could help identifying information gaps and directing future research priorities simultaneously.
  • No Thumbnail Available
    Item
    Studies on the diversity and ecology of zooplankton population in Sundarban Estuarine System (SES), West Bengal, India
    Mandal, Sumit
    Zooplankton play pivotal role in estuarine ecosystem. The relative importance of different environmental parameters in determining the diversity and ecology of zooplankton have been investigated from Sundarban Estuarine System (SES), India. The initial observation was designed to decipher the effect of monsoon on zooplankton species diversity, abundance along with physiochemical factors at river Saptamukhi of SES. Significant intra-monsoonal changes of zooplankton population correlated with several environmental parameters were documented. Additionally, the spatial-temporal distribution of zooplankton were recorded based on different multivariate statistics and indicator value (IndVal) analysis from the river Matla in the eastern part of SES. Seasonal occurrence of dominant taxa with high IndVal index was noticeably observed and it can be used as potential bioindicator for particular season and environmental condition in this estuarine system. Exclusive occurrence of warm water species indicated that the area is under threat of climate change mediated temperature rise. Altogether, 56 zooplankton taxa were identified with copepods forming the predominant population. The zooplankton density was highest in winter, followed by monsoon, summer and spring. Different time series observations were also carried out to unravel the specific diel and tidal variations of economically important shellfish larvae. It has been established that, their early developmental stages utilize the tidal currents for ingress and egress mechanisms in order to migrate horizontal distances and/or remain in their preferred habitats. Moreover, Metapenaeus dobsoni was also selected as a proxy to understand the diel, tidal and ontogenetic changes in their abundance within SES during two different tidal phases. Finally, the impact of climate change mediated elevated temperature on the physiology of a meroplankton species has been assessed through mesocosm experiment by using Penaeus monodon post larvae as a model organism. The growth, survival percentages, ingestion and absorption rate were decreased; howbeit respiration and ammonia excretion rate had been increased in elevated temperature resulted a negative Scope for Growth in stressful environment. The present work provides a benchmark for Sundarban zooplankton species diversity and distribution as well as their diel and tidal variations with respect to different environmental parameters for planning suitable conservation strategies and sustainable development in future.