Nature of spatial heterogeneity of the coastal, marine ecoregions along the eastern coast of India

The Distribution Pattern of Marine Bivalve Death Assemblage From the Western Margin of Bay of Bengal and Its Oceanographic Determinants

“…More importantly, our results show a dominance of infauna-a pattern opposite of what would have been created by this specific preservation bias. This confirms the recent findings of Gupta et al (2020) that the beach assemblages from the eastern coast of India preserve pristine shells pointing to an assemblage enduring the least taphonomic disturbance.…”

High biogeographic and latitudinal variability in gastropod drilling predation on molluscs along the eastern Indian coast: Implications on the history of fossil record of drillholes

“…Based on a large dataset covering a great latitudinal (15°) and biogeographic (c. 2500 km, including several ecoregions and ocean sub-basins) extent, we find extensive spatial variation in drilling predation along the eastern coast of India, which has been observed by others in their local [ 44 ] to regional [ 14 , 26 , 45 – 47 ] to large-scale geographic [ 7 , 8 , 13 , 22 ] studies as well as in fossil records [ 23 – 25 , 48 , 49 ]. The eastern Indian coast is ecologically, sedimentologically, and environmentally very dynamic, showing high variation in the nature of substrate, energy condition, productivity, faunal diversity and composition, and prey ecology [ 28 – 33 , 39 ], which are known to influence drilling predation [ 8 , 22 – 25 ]. Different degree of variation in these confounding variables at different locations, even when temperature and salinity do not vary too much, therefore lead to significant variation in predation.…”

“…Data of different environmental variables known to affect drilling predation locally were gathered for each location and the quantitative variables [data from 39 ] are converted to categorical variables. Following that, all locations are subdivided into: (1) four salinity categories (unit less): 0 = low (up to 30), 1 = moderate (>30–32), 2 = high (>32–34), and 3 = very high (>34); (2) two temperature categories (°C): 0 = low (<28), 1 = moderate (28 and higher); (3) four substrate subcategories based on the prevalence of the nature of sediments: 0 = sandy (S), 1 = Muddy-sandy (MS), 2 = Sandy-rocky (SR), and 3 = Seagrass (SG); and (4) multiple ecoregions [see 32 , 33 ]: 0 for North Bay of Bengal (NBoB), 1 for North Eastern India (NEI), 2 for Central Eastern India (CEI), and 3 for South Eastern India (SEI). Along the eastern Indian coast, NEI includes the West Bengal coast characterized by high turbid conditions; NBoB includes the Odisha coast; CEI and SEI mainly includes the coastal part of Andhra Pradesh and Tamil Nadu, respectively.…”

“…For example, along West Bengal and Odisha, coasts are dominated by mud, whereas the Tamil Nadu coast is dominated by coarse sands along with patches of seagrass habitats, and different location varies in terms of their own geomorphological, sedimentological, and faunal characteristics [ 28 – 31 ]. Because of this complex nature of environmental variation, the eastern Indian coast has been subdivided into multiple ecoregions [see 32 , 33 ]. Moreover, the area of the shallow shelf, which has been identified as an important variable controlling species diversity [ 34 – 37 ], therefore ecological interaction [ 3 , also 38 ], also varies along our studied region [ 39 ].…”