Benthic foraminifera as an environmental proxy for pollutants along the coast of Chennai, India

Benthic foraminifera are increasingly used as an indicator of environmental disturbance. Their sensitivities to pollutants can be reflected by changes in assemblage, which can provide useful information about ecosystem health. This study aimed to investigate the impact of organic and inorganic pollutants on the benthic ecology of the Chennai coast, with a focus on the 2017 oil spill caused by the collision of two ships. Sediment samples collected from five distinct zones along the coast were analysed for pollutants such as polycyclic aromatic hydrocarbons (PAHs), total petroleum hydrocarbons (TPH), heavy metals (Cr, Cd, Pb) and total organic carbon (TOC). The maximum concentrations of Cr (137 μg/g), Cd (6.93 μg/g) and Pb (34.2 μg/g), as well as TPH (84.3 μg/g) and PAHs (227 ng/g), were observed. A total of 47 species of foraminifera were identified in this study, of which 12 were morphologically abnormal. In the low-impact zone, the species diversity index (H') was higher. TPH and PAH concentrations were positively associated with abnormal species. Pollution-resistant foraminifera species include Ammonia tepida, Elphidium discoidale, and Quinqueloculina lamarckiana, while opportunistic foraminifera include Pararotalia curryi, Nonionella stella, Rosalina globularis, and Spirillina vivipara. PAHs and heavy metals were adversely correlated with foraminiferal abundance, while TPH was positively correlated. To assess the response of the benthic ecosystem to hydrocarbon pollution, indices such as the Foraminiferal Index of Environmental Impact (FIEI), Exponential (H'_bc) index and the Foraminiferal Abnormality Index (FAI) were used as environmental health proxies. FIEI, exp(H'_bc) and FAI values show the impact of hydrocarbon pollution to an extent along the northern Chennai coast.

Marine snakes of Indian coasts: historical resume, systematic checklist, toxinology, status, and identification key

We compile an up-to-date checklist of 26 species of marine snakes known from the Indian coastlines. We furnish information on the original orthography, authorship, date of publication, current binominal representation, synonymy and chresonymy lists for each recognized taxon.  In addition, we provide details of name-bearing types, repository and type locality (both original and subsequent restrictions where applicable) of the prevailing nomen for all recognized species.  We summarise the history of research on Indian marine snakes from Linnaeus to the present day, including taxonomic and regional treatises, and highlight the taxonomic flux.  We also provide a revised key for this group to facilitate easier identification and support effective conservation. 

Sediment Oxygen Demand in Cochin backwaters, a tropical estuarine system in the south-west coast of India

Eutrophication has often been one of the major problems encountered in estuaries and coastal waters. The oxic/anoxic status of an estuary can be effectively determined by measurement of the Sediment Oxygen Demand (SOD). The present study forms a pioneering attempt to evaluate the SOD of the Cochin Backwater System (CBS), a tropical eutrophic estuary in the south-west coast of India. The CBS exhibited significant spatio-temporal variations in SOD. The mean net SOD during the dry season (2569.73 μmol O(2) m(-2) h(-1)) was almost twice that of the wet season (1431.28 μmol O(2) m(-2) h(-1)), presumably due to higher discharge during the latter season. The observed pockets of net oxygen release indicate that the CBS still retains certain autotrophic regions in spite of heavy organic drains. The low oxygen flux in light chambers points towards the role of microphytobenthos in maintaining the oxygen reservoir of the estuarine system.