Tracing microplastic pollution in Mahi River estuary, Gulf of Khambhat, Gujarat, and their influence on functional traits of macrobenthos.

Most maritime habitats contain microplastic (MPs) contamination. The quality of the benthic ecosystem's habitat is declining as MPs accumulate in marine system. The contamination of MPs must therefore be investigated. We studied MPs pollution in the Mahi River, estuary, and macrobenthos. In the present study, the abundance of MPs fragments gradually decreased from the high tide zone to the low tide zone and muddy sediment has high MPs concentrations due to sediment characteristics and particle size. The majority of sediment and biota MPs were fibrous and black. MPs in both silt and biota have identical chemical compositions (modified cellulose), shapes, and colors. A significant source of pollutants and MPs fluxing into the ocean is well within the river system. Perinereis aibuhitensis ingested the most MPs out of 11 species, whereas Amphipods did not show any presence of MPs. Our findings showed that functional characteristics are essential for macrobenthos MPs intake. MPs in macrobenthos are high due to biological functions such as feeding, ecological groups, feeding mechanisms, body size, and bioturbation. MPs in marine sediment and organisms are tracked down to the Mahi River exceeding 50 km. The present work has investigated the idea that the macrobenthos that live in the sediment are ingesting the MPs that are building up there and this ingestion relies on the macrobenthos' functional characteristics.

Assessing the benthic quality status of three fine sand tropical beaches from the Andaman Islands through the application of marine biotic indices.

The rapid coastal development in the Andaman Islands has resulted in littoral habitat degradation. Understanding the performances of marine biotic indices and the interpretation and translation of those results into coastal health assessment could become an integral tool in future monitoring and management policies. In this line of efforts, the ecological quality status of three sandy beaches, two urban and one nonurban, was evaluated by using three marine biotic indices. The faunal community belonged to moderately well-sorted fine sand biocenosis. The relatively high species richness (15.9 ± 0.80 taxa sample-1) and moderate abundance (563 ± 38.8 ind.m-2) were features of the benthic fauna. The urban beaches (Aberdeen Bay and Carbyn's Cove) corresponded to tolerant benthic communities. Malacoceros indicus, Grandidierella megnae and Scolelepis squamata (tolerant species), and Ampelisca diadema (indifferent species) were the major constituents of urban beaches, while Scoloplos capensis, Urothoe grimaldii, and Urothoe platydactyla (sensitive species) were important at the nonurban beach (Wandoor). The high-good quality status prevailed across the spatial and temporal scales except for Carbyn's cove beach, where good-poor status was noticed. The M-AMBI appeared to be the most robust measure in distinguishing the impact between the urban and nonurban beaches. The constrained ordinations revealed a gradient of disturbance across the beaches. The distinct patterns of sample segregation were the result of the ecological response. This attempt should be considered a comprehensive measure of quality assessment of beaches under human pressure and draw a parallel line of evidence to global studies on sandy beaches.

Testing performances of marine benthic biotic indices under the strong seasonality in the tropical intertidal habitats, South Andaman, India.

Understanding the natural variability and its influence on the performance of marine biotic indices used for the health assessment of marine ecosystem is the prime concern. This study addresses the seasonal variability of univariate and multimetric indices by using macrobenthic data collected from three intertidal habitats for two years (July 2013-July 2015). The univariate indices viz., abundance, richness, Shannon index and ES (100) showed strong seasonal variability. For the multimetric indices, the seasonal variability was low and appeared site specific. W-statistics, AMBI and M-AMBI showed highest constancy whilst BENTIX and BOPA exhibited wide - ranging. A general tendency could be inferred as majority of indices showed improvement in benthic quality (poor - moderate and good - high) from turbulent monsoon to stable dry period. The results are discussed concerning possible consequences especially related to the benthic community and biotic indices in intertidal habitats under the influence of sewage discharge and monsoonal effects.