%0 Journal Article
%T Aggregation of Euphausia sibogae during Summer Monsoon along the Southwest Coast of India
%A K. J. Jayalakshmi
%A P. Jasmine
%A K. R. Muraleedharan
%A M. P. Prabhakaran
%A H. Habeebrehman
%A Josia Jacob
%A C. T. Achuthankutty
%J Journal of Marine Biology
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/945734
%X The influence of environmental parameters on the spawning aggregation of Euphausia sibogae was investigated along the southwest coast of India during the peak phase of summer monsoon 2005. The prevailing ecological conditions between the aggregation period (peak phase) and non-aggregation period (early phase) were also compared. The aggregation was observed at station 1 ( ; , 480£¿ind¡¤m£¿3) and 6 ( ; , 839£¿ind.m£¿3) during the peak phase of the summer monsoon. Eggs (14769£¿eggs£¿m£¿3) and different developmental stages were observed in higher abundance at station 6. The physicochemical conditions indicated that the aggregation coincided with the upwelling. The nutrient enrichment due to the upwelling triggered phytoplankton blooms, and this appeared to provide a conducive environment for spawning and development of E. sibogae. 1. Introduction The euphausiids (Class: Crustacea; Order: Euphausiacea) are keystone members of planktonic food webs in the coastal and oceanic waters. They act as a link between primary and tertiary producers in the pelagic food web. Being omnivores, their diet includes a broad spectrum of food items, ranging from phytoplankton to small zooplankton to detritus, and even some higher trophic level consumers. Euphausiids are considered as one of the potential prey items for many fish species especially tunnies. According to Roger [1], they contribute to about 15.5% of the total crustacean prey items of Thunnus albacares and Katsuwonus pelamis from the Western Indian Ocean. The young ones (100¨C119£¿mm) of Selar crumenophthalmus prefer 59.9% euphausiid as their main food item. Thus, studies on euphausiids, especially their survival and reproductive strategies are attaining greater importance among researchers. Early studies on euphausiids of the Indian Ocean were carried out by many researchers [2¨C8]. Spatial and temporal variations of euphausiid population along the southwest coast of India have been described by Mathew et al. [9]. Spawning and rapid development of euphausiid characterize the high potential of growth to supply energy and matter to higher trophic levels. Along the southwest coast of India, the breeding of euphausiid species usually coincides with the coastal upwelling during the summer monsoon [10]. The present study aimed to understand (a) the ecological conditions prevailing during the breeding period of E. sibogae, (b) the relationship between phytoplankton standing crop and breeding behaviour of E. sibogae, and (c) the variations in the ecological conditions between the breeding and nonbreeding periods. Coastal upwelling
%U http://www.hindawi.com/journals/jmb/2011/945734/