The nursery function of sandy beaches in a Brazilian tropical bay for 0-group anchovies (Teleostei: Engraulidae): diel, seasonal and spatial patterns

Abstract

The role of sandy beaches as nursery areas for 0-group anchovies (Teleostei: Engraulidae) was investigated in a tropical bay, south-eastern Brazil. Spatial and temporal (diel and seasonal) changes in fish abundance and environmental influences at two beaches were assessed, one located in the outer zone, and the other in the inner zone of Sepetiba Bay. The two sites were sampled quarterly at the same time (0800, 1100, 1400, 1700, 2000, 2300, 0200 and 0500 hours) over a 24 h cycle by beach seine with three replicates, between winter 1998 and autumn 1999. Environmental variables of water temperature, salinity, and transparency (as % depth) were taken at each fish-sampling occasion. Five species in three genera (Anchoa tricolor, A. januaria, A. lyolepis, Cetengraulis edentulus, and Lycengraulis grossidens) were identified. Anchoa tricolor and A. januaria were the most abundant species and indications of spatial separation were detected, with A. tricolor being more abundant in the outer bay (higher salinity and lower temperature), while A. januaria, in the inner bay (lower salinity and higher temperature). Overall, young-of-the-year Engraulidae peaked during the day, perhaps an adaptation to avoid competition with other abundant species which peak at night. Maximum densities of anchovies due to 0-group influxes were found in spring and paucity in summer. Spatial segregation to optimize resource uses and daily habits adapted to take advantage of the rich planktonic bay waters seems to be the strategy developed by these closely related species to use the area during early life cycle. Their high abundances suggest the suitability of the sandy beaches as nursery areas.

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).…”

Macrobenthic surf zone communities of temperate sandy beaches: spatial and temporal patterns

“…This highly productive environment gives rise to a diverse marine fauna (McLachlan & Brown ) acting as refuge, feeding and nursery areas (Lasiak , ; Senta & Kinoshita ; Araújo Silva et al . ; Marin Jarrin et al . ).…”