Assessing the Reliability of Bivalve Species Association as Predictors of Coastal Marine Environments

Koorapati, Ravi Kiran (2017) Assessing the Reliability of Bivalve Species Association as Predictors of Coastal Marine Environments. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Live faunal assemblages often show environment specific species association in shallow marine area. Hence, the marine molluscan species association has often been used as a proxy to reconstruct paleonvironment. However, the reliability of this approach needs to be tested for allochthonous assemblages. Species in a mixed assemblage may not always be autochthonous (i.e., in situ), but may also contain species which may be transported after their death by wave currents. We thus test whether a dead shell assemblage keeps the signature of the environment. Our study focuses on assessing the reliability of recent, dead bivalve species association in predicting different coastal marine environments over a large scale. For this we check how the recent, dead bivalve species are distributed across different marine environments in terms of the variation in species compositions in different marine environments, their ecological guild structure and their taxonomic distinctness. Using spatially-temporally-averages sampling from numerous localities of west coast representing five types of shallow marine environments (sandy shore, rocky shore, estuary, mangrove forest and coral reef) we evaluated the bivalve species composition among the localities. Cluster and NMDS analysis do not show much variations in species compositions across different marine environments. Ecological structures in terms of life modes and attachment types of the species show distinct environment specific assemblages; however, feeding modes do not show any such association. The species across different localities are also not taxonomically distinct as observed from our analysis. The results indicate that the species association of bivalve death-assemblage in the same environments, although similar are not always distinct from the species association in different environments. Thus, bivalve species association might not be a very reliable proxy in reconstructing coastal marine environments in a large scale for paleoecosystems.

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