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2 2021

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Predicting Tachypleus gigas Spawning Distribution with Climate Change in Northeast Coast of India

Pati Siddhartha, Shahimi Salwa, Nandi Debabrata, Sarkar Tanmay, Acharya Satya N., Sheikh Hassan I., Acharya Dipti Kanta, Choudhury Tanupriya, Akbar John B., Nelson Bryan R., Dash Bisnu Prasad, Edinur Hisham Atan

Journal of Ecological Engineering

2021

Vol. 22, nr 3

211--219

Species distribution models are used to predict ideal grounds, species range, and spatial shifts in an ecology over a span of time. With an aim to use Maximum entropy model (MaxEnt), presence records and pseudo-absence points are used to predict the Tachypleus gigas spawning activity for 2030 and 2050 in northeast India. The bearings of sixty T. gigas spawning grounds identified in 2018 were inserted into ArcGIS v.10.1. Meanwhile, 19 environment variables were inserted into MaxEnt v. 3.3.3, before the model performance was tested using receiver operational characteristics and area under curve (AUC). With an AUC of 0.978,85% was achieved for isothermality (bio3) and 74% for temperature (x̄= average) of the wettest quarter (bio8), all of which were inserted into ArcGIS to produce spatial maps. Although we learnt that T. gigas are still spawning in Odisha in 2030 and 2050, their distribution range is predicted to shrink due to the coastal morphology change. The climate conditions in Odisha revolve with the monsoon, summer and winter seasons from which, temperature variations do not only influence the annual absence/presence of spawning adults but also, the survival of juveniles in natal beaches. The use of MaxEnt offers novelty to predict population sustainability of arthropods characterized by oviparous spawning (horseshoe crabs, turtles, terrapins and crocodiles) through which, the government of India can take advantage of the present data to initiate the coastal rehabilitation measures to preserve their spawning grounds.

Is Sex Reversal Common Phenomenon in Horseshoe Crabs Too?

Tudu Sanatan, Sarkar Tanmay, Satyanarayana Behara, Dash Bisnu Prasad, Pati Siddhartha, Chatterji Anil

Ecological Engineering & Environmental Technology

2021

Vol. 22, iss. 4

45--52

The capacity of organisms to change their sex has evolved independently in several species. Sex change has been widely studied, but research approaches have differed and conclusions have often been specific. Although sex allocation theory provides a unifying framework for the study of sex change, this unity has not always been appreciated, Environmental sex reversal (ESR), which results in a mismatch between genotypic and phenotypic sex, is well documented in numerous species and may be induced by chemical exposure. In the present study, an attempt was made to hypothesize the phenomenon of sex reversal in both Asian species (Tachypleus gigas and Carcinoscorpius rotundicauda) of the horseshoe crab in accordance with the size of the animals. Our findings suggest that both Asian species of horseshoe crabs ultimately show a positive sign of sex reversal phenomenon, however, this hypothesis needs further confirmation by studying the hormonal changes at all moulting stages of the horseshoe crab.