Informatics Publishing Limited

V. Rejitha ¹, Valsa S. Peter ¹, M. C. Subhash Peter ¹

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, Kerala, IN

Abstract

Fishes have developed many complex physiological mechanisms to combat osmotic challenges. In this study triiodothyronine (T₃), thyroxine (T₄) and cortisol in the plasma were quantified and the indices of metabolic and hydromineral regulations analyzed in the climbing perch Anabas testudineus after exposing the fish to a selected salinity (20 ppt) for varied intervals (1, 7, 14 and 21 days) to study the physiological basis of short- and long-term salinity acclimation. It was found that transfer of fish to 20 ppt salinity for a day after transient salinity changes, plasma T₄ was elevated, and plasma T₃ decreased whereas plasma cortisol remained unchanged. The levels of these hormones, however, returned to basal levels when these fish were kept for a prolonged acclimation of three weeks. Plasma glucose and lactate showed no change in response to salinity acclimation, whereas plasma urea showed an increase. Substantial increase in the gill Na⁺, K⁺-ATPase activity was found in these fish during salinity acclimation, which remained high even after three weeks. Salinity transfer for a day produced significant increase in the intestinal Na⁺, K⁺-ATPase activity, though it remained unaffected during the long-term acclimation. Kidney Na⁺, K⁺-ATPase activity decreased on day 1 salinity challenge, but remained unaltered after prolonged acclimation. Liver Na⁺, K⁺-ATPase activity increased upon transient salinity challenge but the levels were maintained during prolonged salinity challenge. Our results indicate that salinity acclimation in climbing perch demands thyroid hormone secretion and its action and not cortisol as part of co-ordinating the acclimation processes in the early phase of salinity acclimation. The results also point to the ability of climbing perch to tolerate osmotic challenge, and the fish becomes fully adaptive to brackish water salinity of 20 ppt after three weeks.

Keywords

Climbing Perch, Cortisol, Fish, Na⁺, K⁺-ATPase, Salinity Acclimation, Thyroid Hormones.

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A. S. Vijayasree ¹, V. Rejitha ¹, Valsa S. Peter ², Oommen V. Oommen ¹, M. C. Subhash Peter ¹

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, IN
2 Department of Zoology, Fatima Mata National College, Kollam 691001, IN

Abstract

The physiological response of climbing perch to water-borne nitrate, an important component of the effluents of coconut husk retting, was examined to identify the mechanism of nitrate tolerance in fish. Indices of interrenal function, and metabolic and osmoregulatory homeostasis were analyzed in fish treated with potassium nitrate. Nitrate loading in water for 48 h produced a significant increase in the plasma cortisol by a low dose (247 μM), whereas a higher dose (494 μM) had little effect. A remarkable cortisol surge was found in the nitrate-treated fish kept for recovery in clean water for 96 h, which correlated with the rise in the plasma Na⁺. Glucose, lactate and Na⁺ concentrations in the plasma showed reduction in the nitrate-exposed fish, whereas plasma urea increased. Nitrate exposure had little influence on the gill and kidney Na⁺, K⁺-ATPase activities but had a stimulatory effect on liver Na⁺, K⁺-ATPase activity, indicating a major role of liver in nitrate tolerance. Overall, the present data indicate that nitrate exposure induces an integrated stress response in climbing perch as a result of an activated interrenal axis and disturbed metabolic and hydromineral regulations. This suggests a protective role of cortisol in the regulation of nitrate tolerance in this fish.

Keywords

^{Anabas testudineus}, Fish, Interrenal, Nitrate, Na⁺, K⁺-ATPase, Metabolism, Osmoregulation, Stress.

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J. Leji ¹, G. S. Babitha ², V. Rejitha ¹, A. S. Vijayasree ¹, J. Ignatius ², V. S. Peter ², O. V. Oommen ¹, M. C. S. Peter ¹

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, Kerala, IN
2 Department of Zoology, Fatima Mata National College, Kollam 695001, Kerala, IN

Abstract

The coconut husk retting in the backwaters of Kerala in Southern India, releases toxic effluents (CHRE), which pose a threat to the life of many inhabitants including fish. The indices of osmoregulatory activity and the levels of plasma triiodothyronine (T₃) and thyroxine (T₄) in the Mozambique tilapia Oreochromis mossambicus were quantified after exposing them to the effluents to understand the physiological mechanism of tolerance. The plasma glucose, an indicator of catecholamine secretion, remained unchanged in the tilapia exposed to CHRE. The plasma T₄ significantly increased in the tilapia kept in CHRE-rich water, though it declined in the fish kept for recovery in lake water. The plasma K⁺ significantly decreased in the tilapia treated with CHRE, which returned to the basal levels in those kept for recovery. The Na⁺, Ca²⁺ and PO₄^3- remained the same in both treated and untreated fish. The branchial Na⁺, K⁺-ATPase activity increased in the CHRE-exposed fish, and such an effect was not reversed in the recovery group. The renal Na⁺, K⁺-ATPase activity decreased in the lake water-exposed tilapia but not in the CHRE-treated fish. A reversal in the renal Na⁺, K⁺-ATPase activity was obtained in the tilapia kept for recovery in lake water. The intestinal Na⁺, K⁺-ATPase activity significantly declined in the CHRE-exposed tilapia but not in the recovery group. The data indicate that the presence of CHRE in lake water affects the osmoregulatory potential of tilapia without influencing their metabolic status. The up-regulated thyroid activity in the CHRE-exposed tilapia points to its involvement in the ion homeostasis during CHRE intoxication.

Keywords

Coconut Husk Retting, Fish, Metabolism, Oreochromis mossambicus, Stress, Thyroid Hormones, Tilapia.

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J. Praveen ¹, P. O. Nameer ², Ashish Jha ³, Anish Aravind ⁴, K. G. Dilip ⁵, Dipu Karuthedathu ⁶, George Tom ¹, Hari Mavelikara ⁷, Harikumar Mannar ⁸, Jafer Palot ⁹, Jaichand Johnson ¹⁰, R. Jishnu ¹¹, K. Maxim Rodrigues ¹², P. M. Mujeeb ¹³, L. Namassivayan ¹⁴, Naveelal Payyeri ¹³, P. P. Nesrudheen ⁶, S. Prasanth Narayanan ⁸, S. S. Prasanth ⁶, M. C. Prashantha Krishna ¹², E. S. Praveen ¹⁵, Praveen Velayudhan ¹⁴, Premchand Reghuvaran ⁵, Raju Kidoor ¹², R. L. Rathish ¹⁶, R. Roshnath ¹⁷, C. Sashikumar ⁹, Satyan Meppayur ⁹, A. K. Sivakumar ¹⁰, A. K. Sreedevi ⁸, B. Sreekumar ⁸, E. R. Sreekumar ¹⁸, P. B. Sumesh ¹⁹, R. Venugopal ¹⁴, Vinod Venugopal ²⁰, C. K. Vishnudas ²¹, Vishnupriyan Kartha ⁵, Vivek Puliyeri ⁶, Suhel Quader ²², Abinand Reddy ²², Abdul Raheem Puthiyeri ⁹, K. Abdul Riyas ⁹, R. S. Abhijith ⁸, Abhijith Surendran ⁸, Abhin M. Sunil ¹⁸, Abhinand Chandran ¹³, C. Abhirami ¹⁸, Abhirami M. Jayakumar ¹⁸, Abhishek Sebastian Peter ¹⁰, N. V. Afreed Muhammed ²², Afthab Faisal Katakath ¹⁸, P. Ajai ⁸, Aju K. Raju ⁷, P. M. Akhil ¹⁴, U. S. Akhil ¹⁶, U. S. Amal ²³, Anamika Menon ²⁴, Anas Ibinu Ansari ¹⁵, K. S. Aneesh ¹⁰, S. Aneesh ⁷, C. Anjana Hari ¹⁸, R. Anjitha ¹², P. N. Anoop Raj ²⁵, Anu John ¹¹, Anuradha Varma ⁵, S. S. Anushreedha ¹⁰, C. K. Aravind ⁹, Arjun Ramachandran ¹⁸, B. Arun ⁶, Arun George ¹⁵, Arun P. Gopi ¹⁹, Arun Varghese ⁵, Arya Vinod ¹⁴, Ashley Shaji ¹⁰, V. M. Ashok Raj ⁶, Ashwin Viswanathan ²², Aslam Mohammed ⁹, A. Aswin ¹⁸, K. S. Aswin ¹⁸, A. Azhar Ali ¹⁸, P. B. Balaji ²⁶, M. Bibin Paul ¹⁶, J. Chaithra Shree ²⁶, Chandrasekaran Venkatraman ¹, K. Charutha ¹², Clareena T. Jose ¹⁸, Clince P. Jose ⁹, Dalip Singh ¹⁸, Devika Sanghamithra ¹⁸, Digvijay Singh Sikarwar ⁵, Divin Murukesh ⁶, V. Divin ¹, Fauzia Arief ⁵, Jaydev Mandal ²², P. J. Sarlin ¹⁰, A. Adil Nafar ⁶, K. H. Amitha Bachan ²⁷, V. Rejitha ⁷, R. S. Vishnu Dev ¹⁶, B. Elias Rowther ¹⁰, Firosh Raja ¹⁸, Geetha Iyer ¹, Ginu George ⁵, T. U. Gireesan ⁸, P. K. Girish Mohan ⁹, Glen Preetesh Dsouza ¹², G. Govind ¹⁰, P. Greeshma ¹⁵, P. M. Hari Prasad ⁸, T. V. Hariharan ⁹, A. Harith ¹⁰, C. Harith ¹², B. Hemanth ¹⁰, Ijaas Mohamed ⁵, J. Patrick David ⁵, P. K. Jain ²², P. Jameela ¹⁵, G. Jayakrishnan ⁸, K. Jishnu ⁹, M. O. Jismi ¹⁸, Jithin Johnson ⁵, C. Joel Soniya ¹⁰, Jose Rani Babu ¹⁸, Joseph Roy ¹⁰, Jyothish Nelson ⁸, M. Jyothi Krishnan ¹⁸, K. Pranav Bhandary ¹², K. M. Jamaludheen ⁵, Kavingal Ravi ¹⁴, Karthik Thrikkadeeri ¹⁴, Kausthubh K. Nair ⁵, B. S. Kiran ²¹, Kiran S. Kumar ¹⁰, D. Kishore Raj ¹⁰, Kishore Kumar Panaganti ²², M. Krishna Moorthy ¹⁴, R. Krishna Murthy ¹, M. R. Krishnanunni ¹⁸, Latha Prabhakaran ⁵, K. K. Lathika ⁶, Libin Abraham ⁷, G. Hari Narayanan ⁸, Madhumita Panigrahi ²⁸, S. Manav ¹⁴, Manoj Karingamadathil ¹⁵, T. R. Manoj ²⁶, Manu Thomas ¹⁰, P. P. Manuel ¹⁵, Mebin George Varghese ⁸, P. Megha Chandran ¹², M. Mohammad Sulaiman ¹⁴, Mohammed Ashif Madathil ⁶, V. K. Mohammed Hirash ⁹, K. Mohammed Ramees ¹⁰, M. Sadique Thirunnavaya ⁶, A. P. Muhammed Niyas ¹⁰, C. T. Muhasin ⁶, Mukundan Kizhakkemadham ⁵, Naseerudheen Abdul Azeez ¹⁴, P. V. Nikhil ¹⁰, C. Niranjana ²⁹, Nisha Mundekad ³⁰, Nithin Mohan ¹⁰, A. Pavithra ⁵, Poornima Viswanathan ⁹, P. Pramod ²⁸, G. Prakash ²⁶, S. Prasath ²⁶, Prasoon Prakash ¹⁰, N. Preethi ¹⁴, Rahul Rajeevan ²², M. Rajaguru ¹⁴, V. Rajarajan ¹, Raju Sankaran ¹⁵, K. Ratheesh ¹⁰, Rayan Pradeep Crasta ¹², Remya Mohan ¹⁴, Renju ¹⁹, Robin C. Koshy ⁷, Rohan Rai ¹², Roshin Tom ²², Sachin Chandran ⁹, M. V. Sachinkrishna ¹⁸, M. V. Saeed Anvar Ali ¹⁴, Sajitha Siril ¹⁸, D. D. Samarth Bharadwaj ²², Samuel George ²², Sancia Morris ¹⁰, Sandeep Augustine ⁵, Sandeep K. Das ⁵, Sandie Morris ¹⁰, P. R. Sandra ¹⁵, T. K. Sanuraj ¹², Saurabh Sawant ¹, Savio Morris ¹⁰, K. Selvaganesh ²⁰, K. Shahil ²², N. N. Shahina ¹⁸, Shahul Valasy ⁹, P. K. Siji ¹⁵, Siju Joseph ⁷, R. Sivashankar ¹⁵, Siyad A. Karim ⁷, Sreehari K. Mohan ¹⁸, Sreehari M. Pillai ¹¹, M. Sri Sowmiya ⁹, K. T. Srinila ⁶, K. S. Subin ¹⁵, V. G. Sujith ¹⁰, Suryamol Sukumaran ¹⁰, M. S. Syamili ¹⁸, Tarun Menon ¹⁴, Tejas Praveen ¹, S. A. Thilak ⁵, Tony Antony ³¹, U. R Ullas ³², Vinod Ooralath Sivaji ⁷, Vishnu Narayanan ¹⁰, M. Vishnu Sreejith ⁹, A. Vivek Chandran ¹⁵, Vivek Sudhakaran ¹⁴, R. Vridhi ¹⁵, Wahiba Irshad Humam ¹⁸, Yadukrishna J. Uchummal ²², M. A. Yathumon ⁹

Affiliations
1 KeralaBirder, Ambadi, Kunnathurmedu, Palakkad 678 013, India, IN
2 College of Climate Change and Environmental Science, Kerala Agricultural University, Thrissur 680 656, India; Department of Wildlife Science, College of Forestry, Kerala Agricultural University, Thrissur 680 656, India, IN
3 College of Climate Change and Environmental Science, Kerala Agricultural University, Thrissur 680 656, India, IN
4 Cochin Natural History Society, Revathi Bhavan, Edathala P. O., Aluva 683 561, India; Kottayam Nature Society, Sri Nilayam, Near Union Club, Kottayam 686 001, India, IN
5 Cochin Natural History Society, Revathi Bhavan, Edathala P. O., Aluva 683 561, India, IN
6 Malappuram Birders, Tirur, Malappuram 676 101, India, IN
7 Pathanamthitta Birders, Pathanamthitta 689 645, India, IN
8 Kottayam Nature Society, Sri Nilayam, Near Union Club, Kottayam 686 001, India, IN
9 Malabar Natural History Society, Susheela Mandir, B.G. Road, Nadakkavu P.O., Kozhikode, 673 011, India, IN
10 WWF-India, CO Madhavan Road, Ayyankali Nagar, Kunnukuzhy, Thiruvananthapuram 695 035, India, IN
11 Kollam Birding Battalion, Kollam 691 010, India, IN
12 Kasaragod Birders, Kasaragod 671 121, India, IN
13 Malabar Natural History Society, Susheela Mandir, B.G. Road, Nadakkavu P.O., Kozhikode, 673 011, India; Calicut Birders Club, Bellevue Dental Muthappan Complex, Patteri, Kozhikode 673 016, India, IN
14 Natural History Society of Palakkad, Palakkad 678 001, India, IN
15 Kole Birders Collective, Thrissur 680 555, India, IN
16 Kerala Veterinary and Animal Sciences University, Pookode, Wayanad 673 576, India, IN
17 Malabar Awareness and Rescue Centre For Wildlife, Chettipedika, Kannur 670 004, India, IN
18 Department of Wildlife Science, College of Forestry, Kerala Agricultural University, Thrissur 680 656, India, IN
19 Birders Ezhupunna, Puthiyaparambil (H), Ezhupunna South P. O, Cherthala. Alappuzha 688 537, India, IN
20 Young Birders Club, Palakkad 678 001, India, IN
21 Hume Centre for Ecology and Wildlife Biology, 4th Cross Rd, Subhash Nagar, Kalpetta, Wayanad 673 121, India, IN
22 Nature Conservation Foundation, 1311, ‘Amritha’, 12th Main, Vijayanagar 1st Stage, Mysuru 570 002, India, IN
23 Kollam Birding Battalion, Kollam 691 010, India; Department of Wildlife Science, College of Forestry, Kerala Agricultural University, Thrissur 680 656, India, IN
24 WWF-India, CO Madhavan Road, Ayyankali Nagar, Kunnukuzhy, Thiruvananthapuram 695 035, India; Department of Wildlife Science, College of Forestry, Kerala Agricultural University, Thrissur 680 656, India, IN
25 Natural History Society of Palakkad, Palakkad 678 001, India; Sálim Ali Centre for Ornithology and Natural History, Anaikatty (Post), Coimbatore 641 108, India, IN
26 Sálim Ali Nature Forum, Coimbatore 641 108, India, IN
27 Western Ghats Hornbill Foundation, Extension Centre, MES Asmabi College, P. Vemballur, Thrissur 680 691, India, IN
28 Sálim Ali Nature Forum, Coimbatore 641 108, India; Sálim Ali Centre for Ornithology and Natural History, Anaikatty (Post), Coimbatore 641 108, India, IN
29 Natural History Society of Palakkad, Palakkad 678 001, India; Department of Wildlife Science, College of Forestry, Kerala Agricultural University, Thrissur 680 656, India, IN
30 Cochin Natural History Society, Revathi Bhavan, Edathala P. O., Aluva 683 561, India; Malappuram Birders, Tirur, Malappuram 676 101, India, IN
31 Pathanamthitta Birders, Pathanamthitta 689 645, India; Kottayam Nature Society, Sri Nilayam, Near Union Club, Kottayam 686 001, India, IN
32 WWF-India, CO Madhavan Road, Ayyankali Nagar, Kunnukuzhy, Thiruvananthapuram 695 035, India; Kole Birders Collective, Thrissur 680 555, India, IN

Abstract

Citizen-science driven exercises (e.g. bird surveys) and online platforms (e.g. eBird) provide voluminous data on bird occurrence. However, the semi-structured nature of their data collection makes it difficult to compare bird distribution across space and time. Bird atlases are based on standardized surveys and des­cribe the distribution of bird species over a predefined region and have fewer biases, and thus are better suited for use in research. The recently concluded Kerala Bird Atlas (henceforth KBA) is Asia’s largest bird atlas in terms of geographical extent, sampling effort and species coverage. The entire state of Kerala was systematically surveyed twice a year during 2015–20 and over 0.3 million records of 380 species from 25,000 checklists were aggregated. The dataset was filtered and various metrics were estimated. A total of 915 cells were laid out for systematic surveys, of which 888 were surveyed in either or both the seasons – dry season (January–March) and wet season (July–September); 27 cells could not be surveyed in either of the seasons due to logistical constraints. However, this variation in sampling effort had a minimal effect on survey completeness. The slope of the species accumulation curve suggested near-complete species sampling in over 70% of the cells. After eliminating nocturnal and pelagic species, data from 361 species were analysed. Species count was higher in the dry season than in the wet season. Species richness (count) and evenness were higher in the northern and central districts than in the southern districts. High elevation regions of the southern Western Ghats were the largest contiguous areas lacking sufficient sampling. We found that most of the endemics were concentrated in the Western Ghats, but threatened species were as likely to occur along the coasts as in the Ghats. The KBA dataset is a valuable resource for testing various ecological hypotheses and suggesting science-backed conservation measures. KBA model could be replicated for similar atlases in other states or biogeographic regions of India

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