An Overview of the Determination of Biodiversity of Wetlands

Introduction

Wetlands are considered as one of the significant ecosystems of the globe. They are termed as “biological supermarkets.” for their role in supporting extensive food webs and rich biodiversity. Wetland ecosystems encompasses both aquatic and terrestrial conditions which makes them among the most complex ecosystems of the world. As ecotones, wetlands are embraces various habitats and numerous microhabitats, each one holding atypical, complex, and rich communities. Wetlands are exposed to ecological and topographical gradients, which effect the distribution patterns and zonation of fauna and vegetation. In both inland and coastal wetlands, a gradient exists between almost truly terrestrial sites to permanently flooded plateaus. As a result soil infauna, microbenthic fauna with limited mobility, and vegetation are distributed according to the topographical features determining the gradient itself. Also the environmental features of wetlands are determined largely by hydrologic processes that may fluctuate daily or seasonally in relation to regional climate and geographic conditions. All these factors led to great variety of wetland types globally. Wetlands are broadly classified into five categories i.e., estuarine, marine, riverine, palustrine and lacustrine (Cowardin et.al. 1979, 1992) with recent classification including man-made wetlands. Due to wide range of variety amongst wetland types, the variety of living organisms inhabiting and adapted to the different wetlands tends to be high comprising major taxonomic groups of plants and animals. Wetland vegetation includes representatives of all taxonomic groups - from unicellular algae through bryophytes, mosses and ferns to woody angiosperms. Physiological and morphological adaptations have been reported in plant species of wetlands for long-term survival of flooding and even occasionally with remarkable high plant productivity (Mitsch and Gosselink 2000a; Larcher 2003). The faunal diversity includes representatives of almost all taxonomic categories, from protozoa to mammals. Wetland fauna comprises of two kinds of animals namely those depending entirely on wetlands for their whole life, and those utilizing wetlands for a part of their life cycle or for particular needs. Apart from plant and animal species inhabiting in wetlands they are also utilized by visitor species as well, which in turnintensify the overall biodiversity of wetlands. Wetlands are considered as favoured feeding and resting grounds along migratory flyways for ducks, shorebirds, and waders benefiting from diversity of food organisms. Thus a notable concentration of avian diversity can be seenin different wetlands of the globe. The high avian diversity of wetlands attract large numbers of raptors, making them real reservoirs of biodiversity.Six categories of wetland faunaincludingresidents of the wetland, regular migrants from deep water habitats,migrants from terrestrial uplands, regular migrants from other wetlands, fauna visiting the wetland occasionally and fauna indirectly dependent on wetland biota has been documented by Gopal and Junk (2000).Many regional case studies have documented the value of wetlands as habitat for migratory birds. Two million shorebirds are estimated to visit both the Banc d'Aguin National Park, Mauritania, and the Wadden Sea, Northern Europe; while the St. Lucia estuarine system (a Ramsar site in South Africa) supports 350 species of birds. The Productivity levels of many wetland ecosystems are among the highest in the world. The high productivity levels are directly associated with reservoirs of biodiversity supported by wetlands. These is related to both invertebrate and vertebrate species spending only a particular stage of their lifecycle within the wetlands and vertebrate species taking advantage of seasonal variations in water levelto feed on the wetland's resources. According to Van den Wyngaert and Bobbink (2006) the structure and functioning of wetlands can be strongly influenced by vertebrate herbivory. Wetlands provide myriad of ecosystem services which include food in the form of fish, prawn, rice and many other plants, wastewater purification, hydrological regulation of floods and droughts, regulation of climate etc. The ecosystem services provided by wetlands are critical to the entire life sustaining process in Earth. These ecosystem services are related directly or indirectly to the interactions between different biodiversity components of wetlands and abiotic factors. Finlayson et al. (2005) discussed the ecosystem services provided by different kinds of wetlands. The relationshipsexisting between the processes,ecosystem components, characteristicsand functions of wetlands with goods and services provided by wetlands has been discussed by Maltby (2009). Oertli et al. (2002) reported that many small wetlands together support more biological diversity than one large wetland though some species may occur only in large wetland. Wetlands improve aesthetics and support a widerange of livelihoods apart from various cultural/recreational activities. Overall wetlands contribute to human wellbeing, cultural identity and economic growth. All these factors related to wetland and its biodiversity is possibly the major reason which lead to the fact that conservation and wise use of wetlands gained high priority worldwide. A series of conferences and technical meetings culminated in the ‘Convention on Wetlands of International Importance especially as Waterfowl Habitat’ (well known as the Ramsar Convention) which came into force in 1975. Therefore, wetlands became the only single group of ecosystems to have their own international convention.Also multilateral environmental agreements related to implementation of biodiversity conservation included wetland conservation policies. In this regard Ramsar convention, Convention on Biological Diversity (CBD) and United Nations Framework Convention on Climate Change (UNFCCC) set up mission that are inter-linked and overlapping. As per as wetland biodiversity is concerned The 5th International Wetlands Conference of INTECOL, held in 1996 in Perth, Australia, was devoted specifically to an analysis of the biodiversity of wetlands. The outcome of this symposium was the publication of two volumes (Gopal et al., 2000; 2001) which became the first major global impressions on wetland biodiversity. Also it has been reported that four overarching goals and nineteen specific targets that directly support achievement of both the Sustainable Development Goals (SDGs) as well as the Aichi Targets set up by the Convention on Biological Diversity that have been identified by The Ramsar Convention’s fourth Strategic Plan (2016-2024).Biodiversity of a given ecosystem in general and wetlands in particular provide important insights to ecological health of the said area.