Long-Term Spatiotemporal Variation in the Juvenile Fish Assemblage of the Tramandaí River Estuary (29°S) and Adjacent Coast in Southern Brazil

Abstract

We evaluated connectivity, resiliency, and spatiotemporal variation in fish associations between the Tramandal River estuary (TRE) and the adjacent coast (AC). This was based on intermittent and seasonal data covering a discontinuous 21-year period (1995 to 2016) obtained using a standard beach seine with replicate samples collected at several points. In the TRE (405 samples; 42,987 individuals) 55 species were captured. In the AC (297 samples; 54,295 individuals) 41 species were captured. After data standardization the expected richness of the TRE [E(S) = 18.2] was significantly greater (P < 0.05) than that of the AC [E(S) = 14.4]. The fish association structure and distribution patterns in TRE and AC were dynamic and interconnected but quite different in terms of species composition, especially due to the influence of local salinity. The TRE association was richer in a number of species but numerically dominated by marine estuarine-dependent juveniles. The AC association was represented by a few typical marine species in addition to a couple of estuarine-related transient species who used the surf-zone as a passageway to enter the estuary. Even if there was a higher percentage of common species reported (30 out of 66), the monthly average Jaccard index of similarity (I J = 28%) and the monthly average percent similarity index (I PS = 30%) were low, suggesting that the shallow water functional connectivity between AC and TRE was represented by few species that occur equally in abundance in both environments. Trachinotus marginatus and Mugil liza numerically dominated in the AC and M. liza, Mugil curema, and Atherinella brasiliensis at TRE. Juvenile M liza and M curema added up to >70% of the total individuals sampled in both environments. General linearized models (GLM) revealed that diversity was not influenced by interannual variations, evidencing that juvenile fish assemblage of AC and TRE are resilient through the years. Standardized beach samples are able to reveal long-term fluctuation in shallow estuarine fish communities but without an apparent loss in species composition, richness, and relative total abundance. The only observed interdecadal trend was the reduction in abundance of juvenile M. liza that seemed to parallel the reduction in abundance of the adult fishing stocks in southern Brazil.

Diet and food assimilation of the Plata pompano Trachinotus marginatus Cuvier, 1832 in a subtropical sandy beach inferred by stomach content and stable isotope analyzes

“…Although it was not possible to identify these predated fish to species level, it is highly likely that these consumed specimens were T. marginatus due to its high abundance in the region, compared with other congeneric species (e.g. T. carolinus ) that are rarely found in this area (Lima and Vieira, 2009; Vieira et al ., 2019).…”

“…Thus, the marine surf zone is an important area for the development of juvenile T. marginatus (Monteiro-Neto et al ., 2003; Lima and Vieira, 2009; Lemos et al ., 2011; Vieira et al ., 2019). However, the trophic ecology of this species during its residency in nursery grounds is largely unknown, being restricted only to diet description based on SCA.…”

Comparing beach seine and gillnet sampling methods in fish assemblages from Southern Brazilian shallow coastal lakes

“…Our results point that using beach seines may provide reliable information about changes in fish species richness and composition in shallow coastal lakes, since standardized in time and space and operated by the same people, being a good sampling device for low-cost monitoring projects. (VIEIRA, 2006;CENI;VIEIRA, 2013;VIEIRA et al, 2019).…”

“…In the estuarine zone of the Tramandaí river system and the adjacent seacoast, longterm spatiotemporal variation of juvenile fish assemblage was studied through use of standardized beach seine. Species richness and composition were different between these zones (VIEIRA et al, 2019).…”

Trophic niches and diet shifts of juvenile mullet species coexisting in marine and estuarine habitats

“…For example, the mullets Mugil curema Valenciennes, 1836 and Mugil liza Valenciennes, 1836 are highly euryhaline fishes that occur in marine, estuarine and freshwater ecosystems along tropical, subtropical and temperate systems (Crosetti & Blaber, 2015;Nelson et al, 2016). These species are abundant in temperate and subtropical estuaries, comprising a major part of the fish assemblage in shallow areas (Garcia et al, 2004;Possamai et al, 2018;Vieira et al, 2019). They are marine estuarine-dependent (Elliott et al, 2007) species that usually spawn in the sea whereas juveniles use shallow estuarine areas as nursery and feeding areas (Vieira, 1991;Lemos et al, 2014;Garcia et al, 2018;Mai et al, 2019).…”