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Distribution and Diversity of Macrobenthos in Different e Rese tur arc ul h c & a u D q e A v e f l o o Thilagavathi et al., J Aquac Res Development 2013, 4:6 l p a m n Journal of Aquaculture r e u n o t DOI: 10.4172/2155-9546.1000199 J ISSN: 2155-9546 Research & Development Research Article OpenOpen Access Access Distribution and Diversity of Macrobenthos in Different Mangrove Ecosystems of Tamil Nadu Coast, India Thilagavathi B*, Varadharajan D, Babu A, Manoharan J, Vijayalakshmi S and Balasubramanian T Faculty of Marine Sciences, Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai-608 502, Tamil Nadu, India Abstract This paper deals with the spatial distribution and diversity of macrobenthos and their relationships between physico-chemical parameters of the water and sediment in different mangrove habitats of Tamil Nadu, India during different seasons of the year-2011. Among the different ecosystems of mangrove benthic faunal assemblages, macrofauna density, richness, evenness and Shannon-wiener index were the highest and the Simpson dominance index was medial at riverine mangrove community. However, the Pielou Evenness index of riverine mangrove community was slightly lower than other communities. The similarities among the macrobenthic communities at different sampling sites were determined using Bray-Curtis similarity coefficient and ordinations of non-metric multidimensional scaling (MDS). One hundred fifty six species were recorded in developing (102 polychaetes, 10 bivalves, 11 gastropods, 24 amphipods, 6 isopods and 3 cumacea), two hundred fifty two species were recorded in riverine (151 polychaetes, 12 bivalves, 16 gastropods, 53 amphipods, 16 isopods and 4 cumacea) and one hundred sixty three species were recorded in island mangrove ecosystem (105 polychaetes, 10 bivalves, 16 gastropods, 21 amphipods, 9 isopods and 2 cumacea). Among the three ecosystems, a total of 292 benthic macrofauna consisting of 188 species of polychaetes, 12 species of bivalves, 17 species of gastropods, 55 species of amphipods, 16 species of isopods and 4 species of cumacea were recorded. However, there were obvious differences among the community structures in the three mangrove habitats. This result implied that the different mangrove ecosystem had different effects on the macrofauna communities and shed light on the macrofauna adaptation capability to specific habitats. Keywords: Mangrove ecosystem; Biodiversity; Macro fauna; categories. Indian mangrove ecosystems are known to have a total of Physico-chemical; Seasonal variation 3,985 biological species that include 919 floral species and 3,066 faunal species. Of the biological species, the faunal species occupy about Introduction 77%, and the floral species 23%. Thus, the faunal species component is about three times greater than the floral component of the mangrove Plants ecosystems are a habitat for a wide variety of species, some ecosystem [5,6]. Of these, polychaetes, molluscs, and crustaceans occurring in high densities and provide food and shelter for a large are found to be the major macrobenthic organisms in mangrove number of commercially valuable finfish and shellfishes. They are environment. Most of the macrobenthos assist in the breakdown of productive habitats and support coastal fisheries [1]. The mangrove forests particulate organic material by exposing them to microbes and their are extremely important coastal resources, which are vital for socio- waste materials contain rich nutrients forming the food for other economic development of the region. As a detritus-based ecosystem, consumers. Thus, the macrobenthos plays a major ecological role in leaf litter from the mangroves provides the basis for adjacent aquatic the mangrove ecosystem [7]. Mangroves are inhabited by a variety of and terrestrial food webs. It also serves as breeding, feeding, and nursery macrobenthic invertebrates, such as brachyuran crabs, hermit crabs, grounds for most of the commercially important finfish and shellfishes, gastropods, bivalves, barnacles, sponges, tunicates, polychaetes, and on which thousands of coastal people depend for their livelihood. It is sipunculids. The mangrove invertebrates often exhibit marked zonation considered to have physical, chemical, and biological processes which patterns and colonize a variety of specific micro-environments [8-10]. promote the adaptation of inhabiting organisms to tolerate greater While some species dwell on the sediment. amplitude of environmental characters both morphologically and physiologically. Krom MD and Berner RA [2] have reported that the Materials and Methods decomposition of organic matter consists of nutrients such as nitrogen ′ and phosphorus, which play a vital role in the establishment of healthy Station I (Developing mangrove ecosystem) is located at 11°29 N mangroves. However, sediment where the animals inhabit often acts as buffer either as a source or sink of nutrients especially phosphorus by adsorption and desorption reactions [2,3]. Hence, the sediment plays *Corresponding author: Thilagavathi B, Faculty of Marine Science, Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai-608 a crucial role on benthic faunal diversity in the mangrove ecosystem. 502, Tamil Nadu, India, Tel: 04144-243223; Fax: 04144-243553; E-mail: Benthic organisms constitute an important component that influences [email protected] the productivity of the habitat to a greater extent. Benthos helps in the Received June 26, 2013; Accepted October 22, 2013; Published October 22, recycling of nutrients, which in turn promotes primary productivity. 2013 A detailed and complete knowledge of the bottom fauna is not only Citation: Thilagavathi B, Varadharajan D, Babu A, Manoharan J, Vijayalakshmi important for the determination of productivity [4] but is also helpful S, et al. (2013) Distribution and Diversity of Macrobenthos in Different Mangrove in understanding the diversity of the habitat. Macrofauna are the most Ecosystems of Tamil Nadu Coast, India. J Aquac Res Development 4: 199 doi:10.4172/2155-9546.1000199 widely studied benthic organisms which are retained on 0.5 mm sieve. They reside beneath the sediment surface in burrows and tubes. Thus, Copyright: © 2013 Thilagavathi B, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits seemingly, the bottom of the mangrove substratum habitats forms and unrestricted use, distribution, and reproduction in any medium, provided the a wide array of macrobenthic organisms of various size and taxonomic original author and source are credited. J Aquac Res Development ISSN: 2155-9546 JARD, an open access journal Volume 4 • Isue 6 • 1000199 Citation: Thilagavathi B, Varadharajan D, Babu A, Manoharan J, Vijayalakshmi S, et al. (2013) Distribution and Diversity of Macrobenthos in Different Mangrove Ecosystems of Tamil Nadu Coast, India. J Aquac Res Development 4: 199 doi:10.4172/2155-9546.1000199 Page 2 of 12 79°46′E. This is one of the best-studied estuaries in India comparable by using a calibrated pH pen (Phep; Hanna instruments Mauritius to the world conditions. It is highly productive and rich in floral and Ltd., Portugal) with an accuracy of ± 0.1. The pH in the solution faunal resources. This located estuary remains open with the Bay of was measured using a pH meter, calibrated with standard buffer Bengal as it is a “true estuary” without complete closure of the mouth. solution prior to use. The salinity of samples was measured by using Along the course of this estuary, in an area of 10 ha, a mangrove forest a hand refractometer (Atago, Japan). Water samples were transferred was developed by Dr. K. Kathiresan and his team, CAS in Marine carefully to BOD bottles. The modified Winkler’s method described by Biology, Parangipettai since the year-1991 onwards. It is grown near Strickland JDH and Parsons TR [13] was adopted for the estimation of the shore of Vellar estuary and is very good in supporting biodiversity dissolved oxygen fixed. The nitrate, nitrite, inorganic phosphate, and of many species. Hence, this site was selected as a developing mangrove reactive silicate content of water samples were analyzed by the method ecosystem. of Strickland JDH [13]. Station II (Riverine mangrove ecosystem) is located at 10°20′N Sediment sampling and analysis of physico-chemical ′ 79°32 E and it is situated 400 km south of Chennai which lies on the parameters southern part of Cauvery delta region along the south east coast of the Peninsular India. Avicennia marina is the dominant mangrove species Pterson’s grab (0.256 m2) was used to collect sediment samples. in Muthupettai and accounts for nearly 95% of the vegetative cover. In The soil temperature was measured using a standard centigrade Muthupettai mangrove harbours, 112 species of insects 14 species of thermometer by directly inserting in the sediment. The soil pH was crustaceans, 18 species of molluscs, 73 species of finfishes, 10 species of determined by adopting the method of Jackson ML [14]. Water was herpeto fauna and 13 species of mammals [11,12]. added to air-dried samples in the ratio of 1:1 and stirred in a mechanical Station III (Island mangrove ecosystem) consists of three different shaker for an hour, and pH was measured in this solution. A known islands of Gulf of Mannar, namely Kurusadai, Poomarchan, and amount of sediment samples was moisturized with double distilled Manauli. It is located between 9°14′N 79°12′E and 9°12′N 79°7′E, along water up to the moisture saturation of the
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