Species composition and dynamics of larval and juvenile fishes in the surf zone of Mauritius

Abstract

The importance of the surf zone as a nursery ground for larval and juvenile fishes has been widely recognized, however the zone has yet to be studied in Mauritius. Recently, the coastal area of the island has been increasingly affected by human activities, especially by tourism. We collected fish samples with a hand pulled seine net during the period of August 2001 to March 2003 to clarify the fish fauna and the dynamics of fishes in the surf zone. Two sampling sites adjacent to river mouth areas and one sampling site adjacent to a mangrove area were selected for comparison of fish fauna in relation to environmental conditions. A total of 9,429 fish larvae and juveniles, representing at least 112 species from 48 families were collected. The abundant species were hardyhead silverside, Atherinomorus lacunosus, bluespot mullet, Valamugil seheli, and Ambassis spp., each contributing 16.2, 12.4, and 11.8% of the total number of individuals, respectively. Estuarine species dominated in the surf zone adjacent to the river mouth areas. Species composition and diversity changed seasonally. The number of fish increased during the rainy season. Species diversity increased at the turn of the seasons from the dry season to the rainy season. We conclude that species composition in each site was affected by environmental factors, such as the scale of the flux from the rivers, which is related to the precipitation. The results indicated that freshwater from the river is a trigger to aggregate larvae and juveniles in the surf zone.

Confirmation of the presence and use of sandy beach surf-zones by juvenile Chinook salmon

“…Juveniles were sampled in the surf-zone of a sandy beach in southern Oregon sub-yearling Chinook salmon sampled in the surf-zone of a sandy beach in southern Oregon imately 66% of the Oregon coastline are sandy beaches (Don et al 2006). The use of the surf-zone of sandy beaches as important habitat or nursery area for several species of juvenile fish has been suggested in previous studies (Beyst et al 2002;Silva et al 2004;McLachlan and Brown 2006;Sato et al 2008).…”

“…The surf-zone has been suggested to offer larval and juvenile fish an abundant supply of potential prey and shelter from predators (Beyst et al 2002;Barreiros et al 2004;Silva et al 2004;Crawley et al 2006;Sato et al 2008), both of which could increase their survival rate. At beaches close to large estuaries, the surf-zone contains relatively low-salinity water masses, which has been shown to attract juvenile fish that have just entered the ocean (Fisher and Pearcy 1995).…”

“…Belgium, Brazil, The Netherlands, and South Africa (review by McLachlan and Brown 2006). These studies have found the surf-zone fish community to be composed mostly of larvae and juveniles, which may be using the area as a nursery or as migratory path to other nurseries (Beyst et al 2002;Silva et al 2004;Sato et al 2008). Most of the surf-zone fish feed on benthic organisms and zooplankton, and are characterized by highly variable abundance in space and time, potentially due to the fish's opportunistic feeding behavior (McLachlan and Brown 2006).…”

“…Most of the surf-zone fish feed on benthic organisms and zooplankton, and are characterized by highly variable abundance in space and time, potentially due to the fish's opportunistic feeding behavior (McLachlan and Brown 2006). Possible reasons for the use of the surf-zone of sandy beaches by larval and juvenile fish are an abundant supply of potential prey and shelter from predators (Beyst et al 2002;Silva et al 2004;Sato et al 2008).…”

Spring and Summer Larval Fish Assemblages in the Surf Zone and Nearshore off Northern New Jersey, USA

“…In contrast to ecological characterizations of larval fish assemblages in coral reef (e.g., Mora and Sale 2002;DeMartini and Friedlander 2004), rocky reef (e.g., Borges et al 2007;Marliave 1986), shelf/bay (e.g., Cowen et al 1993;McBride and Able 1994;Jessop et al 2007), and estuarine (Allen and Barker 1990;Able and Fahay 1998;Witting et al 1999) environments, far less is known about the larval fish composition of shallow nearshore and surf zones. Studies of surf zone larval fish ecology are restricted in geographic scope, primarily to South Africa (Whitfield 1989;Cowley et al 2001;Harris et al 2001;Watt-Pringle and Strydom 2003), Mauritius (Sato et al 2008), and Japan (Senta and Kinoshita 1985;Suda et al 2002), and studies in the USA are limited to the Gulf of Mexico (Ruple 1984;Sanvicente-Añorve et al 1998).…”