Ecological analogies between estuarine bottom trawl fish assemblages from Patos Lagoon, Rio Grande do Sul, Brazil and York River, Virginia, USA

Abstract

The structure of estuarine fish assemblages at temperate latitudes in Patos Lagoon (32º05'S, 52º04'W), Rio Grande do Sul, Brazil and York River (37º17'N, 76º33'W), Virginia, USA was compared using mid and late 1970's data from bottom trawl collection to investigate whether geographically isolated fish assemblages have similar ecological structure given similar latitudinal positions on the warmtemperate southwestern and northwestern Atlantic regions, respectively. Since estuarine species often exhibit an ontogenetic shift in habitat requirements or preferences we examined Capture per Unity of Effort by size class (CPUE-SC) and split species into "size ecological taxa" (SET) for analysis. The use of CPUE-SC also allowed the abundance of a SET to be computed by summing the mean CPUE of each size class within that SET and use this information to follows SET's temporal and or spatial abundance. A total of 65 and 63 species was collected during a year of bottom trawling in the Patos Lagoon and York River estuaries, respectively. In both localities the strongest modal size class was < 80 mm TL, and several abundant species were smaller than 100 mm TL. The size between 80 and 100 TL effectively separated several species into discrete SET's in both systems. Those SET's could have different ecological preferences, temporal and spatial distributions and so identified as different "ecological taxa". In warm months, when predation by large fish is most likely, the abundance of fish between 80 and 100 mm TL in "bottom trawl" demersal fish assemblages was low in both systems. Only the sea catfishes, in Patos Lagoon, protected by strong dorsal and pectoral spines, and the Hogchoker, in the York River, protected by burrowing in the bottom substrate, peak in abundance at this size class. The seasonal pattern of estuarine use was similar between localities and did not differ from other warm-temperate estuarine fish assemblages.

Whitemouth croaker Micropogonias furnieri (Desmarest, 1823) feeding strategies across four southern Brazilian estuaries

“…Species abundance (catch per unit effort, CPUE), and size (TL) data were analyzed graphically by plotting CPUE (individuals per sample) by TL classes (Vieira 1991;Garcia et al 2003a;Vieira 2006). We compared the size frequency distributions of whitemouth croaker in the four estuaries using nonparametric Kruskal-Wallis ANOVA (Zar 1984;Sokal and Rholf 1981).…”

Review and consideration on habitat use, distribution and life history of Lycengraulis grossidens (Agassiz, 1829) (Actinopterygii, Clupeiformes, Engraulididae)

“…In the Patos Lagoon Estuary, the species occurs throughout the year (Buckup 1984, Chao et al 1985, Ramos 2005, and was among the ten most abundant species of shallow waters , bottom trawl (Vieira 2006) and dominated the pelagic assemblage (Vieira & Castello 1997). At Patos Lagoon Estuary salinity appears to segregate different age cohorts of L. grossidens, with larvae preferring oligohaline waters for their development (Castello & Krug 1978), besides which the relative abundance of juveniles is higher in El Niño than La Niña years (Garcia et al 2001).…”

Dealing with temporal variation and different life stages of whitemouth croaker Micropogonias furnieri (Actinopterygii, Sciaenidae) in species distribution modeling to improve essential estuarine fish habitat identification

“…All these habitats provide nursery areas for a wide variety of species, including whitemouth croaker (Seeliger, 2001), which depend on this ecosystem to successfully develop, feed, and grow. The whitemouth croaker is an important target fish species in the local PLE artisanal fishery (Odebrecht et al 2010), and individuals ranging in age from the early stages to adulthood can be found year-round inhabiting the lagoon (Castello, 1986;Muelbert & Weiss, 1991;Vieira, 2006).…”