Checklist of Intertidal Benthic Macrofauna of a Brackish Water Coastal Lagoon on East Coast of India: The Chilika Lake

Debasish Mahapatro<sup>1</sup>; R.C. Panigrahy; S. Panda<sup>2</sup>; R.K. Mishra<sup>3</sup>

Checklist of Intertidal Benthic Macrofauna of a Brackish Water Coastal Lagoon on East Coast of India: The Chilika Lake

Debasish Mahapatro¹

, R.C. Panigrahy

, S. Panda²

, R.K. Mishra³

1. Department of Marine Science, Berhampur University, Berhampr, Ganjam Odisha, India
2. Department of Forest and Environment, Odisha, India
3. National Centre for Antarctic and Ocean Research (NCAOR), MoES, Goa- 403 804 India

Author

Correspondence author
International Journal of Marine Science, 2015, Vol. 5, No. 33 doi: 10.5376/ijms.2015.05.0033
Received: 10 Mar., 2015 Accepted: 16 May, 2015 Published: 25 May, 2015

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Preferred citation for this article:

Mahapatro et al., 2015, Checklist of intertidal benthic macrofauna of a brackish water coastal lagoon on east coast of India: The Chilika lake, International Journal of Marine Science, Vol.5, No.33 1-13 (doi: 10.5376/ijms.2015.05.0033)

Abstract

During the present inventory related to benthic macrofaunal assemblage in the intertidal region of outer channel area encompassing the period from 2007 to 2010, recorded a total of 135 species from 8 phyla. The phylum annelid became the major group having 46 species followed by mollusca with 41 species. The class polychaeta emerged as the dominant group with 39 species followed by the class bivalve having 21 species. Some of the taxa substantiated during the study period predominantly occurred throughout the study period were those of Spongilla alba, Membranipora bengalensis, Capitella capitata,Minuspio cirrifera, Heromastus filliformis, Grandidierella taihuensis, Niphargus chilkensis, Quadrimaera incerta, Ampithoe ramondi, Mesopodopsis orientalis, Ctenapseudes chilkensis, Alpheus edwardsii, Uca sp., Diogenes custos,Remipessp.,Amphibalanus Amphitrite, Chironomus, Lepas (Anatifa) anatifera, Meretrix meretrix, Mactra stultorum,Brachidontes striatulus, Solen annandalei, Crassostrea cuttackensis, Bufonaria echinata, Epitonium clathrus Nassarious stolatus, Umbonium vestiarium, Astropecten bengalensis, Ichthyocampus carce etc. One rare species namely Hippocampus fuscus was recorded during the present study from the sea grass meadows. Among environmental parameters salinity and chlorophyll a appeared as the major factor controlling the intertidal macrobenthos of outer channel area significantly. Strong seasonal heterogeneity was also observed in the environmental parameters like salinity, DO etc together with number of macrobenthos taxa. Among significant observation, higher number of macrobenthos taxa in summer season as compared to monsoon season in both years of study was evidenced. Since many of the newly occurring taxa in the lagoon premises were of typical marine formsobserved during 2009-10 study year, hence the present study strongly supported that the opening of a new lagoon inlethave positive impact on benthic macrofaunal assemblage of the intertidal region.

Keywords

Outer channel area; Chilika lake; Intertidal region; Benthic macrofauna

Coastal lagoons are usually shallow brackish water ecosystem, highly productive and dynamic in nature. They are found in the transitional zone between continental land mass & oceanic milieu (Anthony et al., 2009; Mohapatro et al., 2013). According to Kjerfve (1994), coastal lagoons are defined as “an inland water body, usually oriented parallel to the coast, separated from the ocean by a barrier, connected to the ocean by one or more restricted inlets, and having depths which seldom exceed a couple of meter”. The intertidal zones of such shallow coastal lagoons are positioned high among the most productive marine ecosystems in the world (Alongi 1990; Heip et al., 1995; Panigrahy 2000; Anthony et al., 2009; Mohapatro et al., 2013). In general, the benthic communities of such intertidal region are considered as the pioneer components of coastal and marine ecosystem process (Lu, 2005). Factors affecting significantly on intertidal macrobenthos are those of frequent tidal incursion, sharp declination in salinity and seasonal variation of different abiotic parameters (Alongi, 1990; Ysebaert et al., 2002). The sediment composition is also considered as one of the important parameter to the intertidal organisms which determines larval recruitment and settlement followed by species composition (Sanders, 1958, Gray, 1974, Warwick et al., 1990). It has been well documented by Herman et al. (1999) and Riisgård & Kamermans (2001) that the macrobenthos community is mostly feed up on microphytobenthos or phytoplankton whereas some of them also use detritus materials such as the debris of sea weeds, sea grass and other macrophyte vegetation as their chief source of food (Créach et al., 1997). Thus intertidal zones become the most suitable region for many of the fishes, shellfishes, shorebirds and benthic macroinvertebrates to colonies for feeding and breeding process (Alongi, 1990, Ysebaert et al., 2002; Elias et al., 2005). Impact of natural and anthropogenic stress on intertidal macrobenthos might be drastic. According to Alongi (1990), any alteration in the species composition of intertidal macrobenthic community due to natural event and/or anthropogenic stress have deleterious effect on species composition and abundance of tertiary consumers of higher trophic strata like fishes, migratory birds, even for dolphins with respect to time and space. Thus intertidal benthos plays a critical role in coastal biodiversity. It also decipher immense ecological functioning such as variation in the physical and chemical composition of sediment (Gaudencio and Cabral, 2007; Shou et al., 2009), recycling of nutrients, metabolism of different pollutants and secondary production (Snelgrove, 1998). Some of the sessile intertidal organisms are the best source of bioactive compounds; even few of them are also used in the ecotoxicological studies such as heavy metal, PCB, PHC. Because of their sessile mode of life style and capability to withstand under environmental extreme conditions, these are often used as the suitable indicators of pollution or environmental stress (Dauer, 1993). With these facts and information, the present study is basically designed for the documentation of intertidal macrobenthos and other megabenthic organism in the outer channel area of Chilika lake.

Chilika lake is the largest brackish water coastal ecosystem in Asia and second largest in the world, enriched with biodiversity and a rich source of large scale exploitable fishery resources. It appeared as the largest habitat for migratory bird species and Irrawaddy dolphin (Panigrahy, 2000; Panda et al., 2009). Research on biodiversity aspect of Chilika lake has been started since a century ago which has been evidenced by the perusal of literature such as Preston (1915), Annandale (1915), Annandale and Kemp (1915), Sewell and Annandale (1922). They reported details of the macrobenthic community distribution and species composition. Later Rajan (1965), Patnaik (1971), Sarma et al. (1981) and ZSI (1995) have furnished good amount of information related to the various aspects of bottom fauna of Chilika. Besides this, there are hundreds of literature available related to biodiversity, fisheries, hydrography, change in geomorphology, pollution aspects etc. But there is no literature available to enumerate the intertidal benthic fauna of Chilika lake. Therefore, to fill this gap of information, the present study is designed (i) to develop a comprehensive checklist of macrobenthic community of Chilika lake residing in the Outer channel area including mega-benthic fauna, (ii) to compare the environmental data and no. of macrobenthos taxa between two periods i.e. before the opening of natural inlet during 2007-08 (one inlet) with the data of the year 2009-10 (two inlet), (iii) to find out the correlation between different environmental parameter with number of macrobenthic taxa recorded during the study period.

1 Material and Methods

Study area-Chilika lake which is also regarded as a coastal lagoon, located between 19^o28’and 19^o 54’N and 85^o 05’and 85^o38’E (Figure 1). It is the largest brackish water coastal ecosystem in Asia and situated on the east coast of India. The pear-shaped water body of Chilika lake measure about 64.5 km long and width varies from 5 km to18 km where as the water spread area has been estimated from 906 sq. km in summer to 1165 in monsoon seasons (Panda et al., 2009). Ecologically, the lagoon can be divided in to four sub-ecosystems such as Northern sector (fresh water), Central sector (Brackish water), Southern sector (Brackish-cum-marine water) and outer channel area having the marine characteristics (Panda et al., 2009).

Figure 1 Map of Chilika lake showing four ecological sectors, dredged inlet (opened during 23^rd September 2000) and Natural inlet (opened during 1^st August 2008)

The outer channel is 32 kilometer long channel connects the lagoon with the Bay of Bengal through couple on inlets (“Shipakuda inlet” and “Gobakunda inlet”). Another man made channel of 16 kilometers long called “Palur Canal” is connected with the lake at the southern tip. This channel is started from the Rushikulya estuary and brings sea water from Bay of Bengal under the influence of tidal rhythm towards the southern sector of the lake. Salinity becomes the main guiding parameter and thus strongly determines the distribution of flora and fauna of it. The Nalabana Is. of Chilika lake is the shallow area with exposed soft sediment. During winters it become the major feeding, breeding and nesting ground of migratory and residential birds. It provides homage to 0.1 million of population of wintering birds every year. Furthermore, the lake is also acts as an ideal habitat for Irrawaddy dolphins. More than 10,000 mt of fisheries output per annum is reported from Chilika lake. Thus, it provides livelihood support to 0.2 million of fisher folk. Like other coastal ecosystems, Chilika lake ecosystem also faced sever environmental degradation due to closing of a lagoon inlet during the last decade of 20^th century. As a consequence of such event, the lagoon-sea interaction had been cut off completely. Salinity followed by fisheries output in the lake was dropdown drastically. This had not only created a major a concern about the socioeconomics of the local people but also a eutrophic condition was developed.

In order to develop the previous pristine brackish water characteristics of the lake by increasing the salinity level vis-a-vis fisheries output, a dredged mouth was opened during 23^rd September 2000 which was named as “Shipakuda inlet”. After two years of opening of this dredged inlet, the fisheries output was increased up to 7 folds where as the desired salinity level was maintained (Mohapatra et al., 2007; Panda et al., 2009). After 8 years of this hydrological intervention, another mouth was opened by natural process (1 km northeast of the dredged mouth) during the year 2008. This natural inlet was termed as “Gobakunda inlet” (CDA, 2010). Both these inlets put major role in the sediment & water exchange between the lagoon and sea. However, very less study was carried out regarding this to explain the change in water quality and biodiversity.

1.1 Outer channel- general information

Outer channel is the marine influenced region of Chilika lake having the length of 18 km and width varies from 200 m to 2 km. This is the deeper region of Chilika lake having observed depth more than 3 m while during monsoon its depth is significantly high due to massive ingress of fresh water from the northern and western catchment. The sediment texture of this region is varied from coarse sand to fine sand while many patches of soft bottom sediment were also seen. Some areas those are called as intertidal mudflats usually located at the sheltered region of the new inlet channels. The Shipakuda region of outer channel area is covered with artificially implanted mangrove vegetation. The flank areas are occupied with shoreline vegetation such as Casuarina plantation, halophytes and grasses where as the bottom of the intertidal sediment is dominated with the occurrence of sea grass meadows and sea weeds. Five species of sea grass were observed in the outer channel region such as Halophila ovalis, Halophila ovata, Halophila beccari, Halodule pinnifolia and Halodule uninervis. This can be visualised in a better manner during the low tide periods. Besides these many brackish water macrophyte are reported from outer channel area such as Ruppia maritima,Potamogetone pectinatusetc. Among sea weeds Chaetomorpha linum, Enetromorpha sp., Ulva sp.etc become conspicuous. Large bed of bivalve community belonging to Crassostrea cuttackensis and Meretrix sp., are frequently observed in the low tide periods nearer to the“Manikpatana”, “Arakhkuda”, “Gobakunda” and “Shipakuda” region of outer channel area. During winter season, the shoreline areas are ofte

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