Wetlands, Fishes and Pandemics with Special Reference to India

Water is life, life is water. Water is indispensably important for sustenance of life. Wetlands serve as potential water bodies, harbouring coveted bioresources, which sustain animal life. Fish is a significant bioresource for nutrition and avocation of the people. There are various types of wetlands in the Indian sub-continent. India has c 67,429 wetlands covering c 4.1 million ha. Concomitantly, c 21,723 living species of fish have been recorded out of 39,900 species of vertebrates. Of these, c 8411 are freshwater (FW) species and c 11,650 are marine. India recorded c 2500 species of fishes; of which, c 930 live in FW and c 1570 are marine. The hitherto unknown dreadful, virulent, enigmatic Epizootic Ulcerative Syndrome (EUS), has been sweeping the FW fishes in an epidemic dimension, unhindered, unimpeded and unabated, almost semi-globally; and, has been causing large-scale mortality among them, since 1988, rendering many of them endangered. Concomitantly, the outbreak of SARS-CoV-2, among the human, was first reported at Wuhan, China, in late December 2019. The first 54 reported cases of COVID-19 were observed in December 2019 at Wuhan, China, and this, subsequently, had spread across the globe. India has been facing much impacts of COVID19 pandemic since its inception in China.

and, might have further reduced.
The North-East (NE) India, the hotspot of Biodiversity, having undulating terrains, provides rich potential for fish production, which could supplement its nutritional requirements and could provide with an answer to diminishing protein supply. Further, in Assam, the different kinds of wetlands cover c 100,000.0 ha having been locally named as "Beel, Haor, Anua, Hola, Doloni, Jalah," etc.; with areas from 35.0 to 3458.12 ha and depth from 0.25 to 3.0 m; although, some may be as deep as 6.0 m at FSL. Concomitant to above: (a) a "Beel", is a perennial wetland; b) a "Haor", is a seasonal floodplain wetland; and, (c) "Anua" a a river-formed oxbow wetland. In Assam, there are c 490 Beels, 610 Haors and 290 Anuas.They contain a rich diversity of fish fauna and also other aquatic biota. The wetlands are also associated with the cultural ethos of the people. Kushiara, which flows into Bangladesh. Thus, there is retention of higher silt load in the Beel through the inlet in contrast to low expulsion through the outlet; thus leading to fast shrinkage of water spread area of the Beel. The values of different limnological parameters ranged from turbidity,20.56 TU to 185.54 TU; water temperature 18.7 to 32.3 o C; pH 6.02 to 7.9; DO 2.6 to 5.9 mg lit. -1 ; DO solubility 9.4 to 11.9 mg lit. -1 ; % saturation of DO 32.3 to 74.4%; FCO 2 0.9 to 14.5 mg lit. -1 ; and, TA 25.0 to 76.0 mg lit. -1 . The conductivity of Sone water was low. The pH of Sone Beel soil ranged from 5.02 to 5.9; OC 0.25 to 1.74 %, available phosphorus from 0.15 to 1.93 mg 100 g -1 and available potassium from 1.62 to 24.8 mg 100 g -1 . The phytoplankton (PP) included 47 forms under 7 families; while, PP density varied from 10 to 5308 units lit. -1 having abundance of chrysophytes and rarity of pyrrophytes.

Some of the Wetlands Exemplified
The zooplankton (ZP) contained 19 forms with the density ranging from 6 to 380 units lit. -1 . The copepods and cladocerans were the most abundant and the protozoans, the least. There were 23 species of Aquatic Macrophytes (AM) in Sone Beel and the AM biomass vried from 0.50 to 21.90 kg m -2 .
Eichhornia crassipes, Hydrilla verticillata and Trapa bispinosa were the most abundant species perennially. And, the littoral fauna, represented by both piscian and non-piscian groups, exhibited biomass of the former from 0.05 to 1.53 g m -2 while that of the latter from 1.6 x 10 -4 to 1.09g m -2 . Of    (Kar, 2015). The filterable biological particles were different from those described by Frerichs et al. (1986). Further, recent studies revealed the detection of Ranavirus infection in cultivated carps of North-East India (Kar, 2007(Kar, , 2013(Kar, , 2015(Kar, , 2019Riji et al., 2016). Electron Microscopic studies with the ultra-thin sections of still-occurring EUS-affected fish tissues, revealed the presence of virus-like particles (inclusion bodies); and, preliminarily, the picobirna virus has been electron microscopically identified as the primary aetiological agent of EUS (Kar, 2015).

SARS CoV2 (COVID-19)
Notwithstanding the above, the outbreak of SARS-CoV-2 was first reported at Wuhan, China, in late

A View
Based on the long experience of the present author in dealing with pandemics, he convincingly feels that, stress factor in the initiation of EUS disease in the fishes. These are important inputs which the world is looking forward to.

Conclusion
Information on the hydrobiological conditions of any water body is of prime necessity before endeavouring to utilize it as a productive fishery. Proper planning depends on the availability of reliable data.
Wetlands have been derelicted and transformed by activities like unplanned urban and agricultural development, industrial sites, road construction, impoundment, resource extraction, etc., causing substantial long-term economic and ecological loss. There have been records of c 147 wetland sites in India. Approx. Records of wetland loses are: c 32% primarily through hunting and associated disturbances; c 22% due to human settlements; c 19% due to fishing and associated disturbances, and, c 23% through drainage for agriculture; c 20 % due to pollution from industries; c 15 % due to catchment vegetation denudation followed by soil erosion and siltation; and, so on. Further, c 4000 km 2 of mangrove area is said to be in existence in India. Wetland loss in India and in many other countries could lead to serious consequences; as, large human populations and many other biota depend on these wetlands.
Notwithstanding the above, wetlands have been an integral part of the social and cultural ethos of the Indians; and, their life have been very closely associated with the wetlands since time immemorial.
People living close to wetlands follow the natural cycle of floods and adjust themselves to the seasonal movements of the fish. The fishes are harvested based mainly on changing water levels. However, due to poor resource base and livelihood insecurity in some parts of the country, there is generally irrational harvest from the wetlands. Such activities lead to rapid degradation and destruction of the wetlands.
It is, therefore, imperative to conserve the wetlands and protect their unique biodiversity. The wetlands could and do serve as the source of livelihood for a large number of people. So, they are to be properly conserved and managed. Moreover, if the natural environmental conditions are improved, there could be less probability of large-scale pandemics to occur.