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The consistency and environmental correlates of habitat- and season-related differences among shallow-water fish assemblages inhabiting estuarine beaches (EB) and tidal flats (TF) were examined in the subtropical Paranaguá estuary, which borders a World Heritage listed area. Assemblages were diurnally sampled each month (May 2003–March 2004) using small-meshed beach seines. Forty-six and 49 species were captured at EB (24 families) and TF (23 families), with most individuals at the latter (66 and 54% by number and biomass). Resident fishes accounted for 74% of individuals, but only 31% of all species. Most species were juvenile marine transients, but occurred sporadically and in low numbers. Three residents ( Sphoeroides testudineus , Atherinella brasiliensis and Sphoeroides greeleyi ) dominated assemblages and contributed the most to the index of relative importance of each habitat. Habitat-related differences in assemblages and key population parameters were complex and generally depended on the month sampled rather than water salinity or temperature (owing to comparable temporal variability). Ocean proximity was probably the cause of some differences, with more recruits of marine species early in the wet season at EB, but later at TF. Nevertheless, some resident gobiids and paralichthyids displayed habitat partitioning, possibly related to sediment preferences. There were strong seasonal differences in assemblages, primarily due to more juveniles of resident and transient species during the wet and possibly reflecting more optimal conditions for the young-of-the-year survival due to increased primary and secondary productivity. Environmental correlates of salinity and temperature with assemblage parameters were generally weak, but increasing water temperature prior to the wet season may be a key driver for reproduction, so that larvae are delivered during the wet season. The shallow, low-energy sandy beaches and tidal flats are used by a large diversity of fish, and consequently need to be considered in conservation and biodiversity estuary management plans. [ABSTRACT FROM AUTHOR]

Diel and tidal variations of fish assemblages were assessed at Pontal beach, southern Brazil, using a seine net. Species richness was greater at night, whereas fish number, weight, and richness (community indicators) were all influenced by the tidal state. Samples from rising tides were more representative, probably due to onshore fish movements for feeding purposes. However, lower catches were associated with high tides, mainly through net avoidance, indicating that sampling in these conditions is not highly informative. Clupeoids exhibited greater variation in a 24 h period, and the night occurrence of A. tricolor and daylight shoaling of Harengula clupeola, Anchoa parva and Sardinella brasiliensis suggested distinct strategies for avoiding daylight predators. In some species, this behaviour may have been induced by the bottom morphology and tidal state, facilitating nearshore grouping. In addition to being caught at night, the occurrences of Menticirrhus littoralis, Pomadasys corvinaeformis, Umbrina coroides and Hyporhamphus unifasciatus indicated a spatial niche partition according to tidal state. Although not evaluated properly, temporal fluctuations could reflect species recruitment patterns. Seasonal fluctuations have to be considered when analysing short-term changes in the community as such fluctuations are synchronized with the natural history of the species, making it difficult to interpret short-term variations in isolation. [ABSTRACT FROM AUTHOR]

Evaluates the exchange and magnitude of flux of larval fishes in the U.S. Observation of the sea-surface temperature; Distribution of heat and salt; Identification of the planktonic particles.

To promote marine conservation and sustainable resources use it is highly important to understand reef fish population structure and dynamics. The sergeant major, Abudefduf saxatilis, is a common and abundant fish usually found in the Brazilian coasts, being considered a keystone-species for structuring benthic communities on reef habitats in the Atlantic Ocean. This study examined the morphology (shape indices and elliptic Fourier descriptors) and chemistry (Element:Ca) of A. saxatilis sagittal otoliths, collected in seven locations along the coast of South Brazil. Otolith morphology and chemistry were compared at short (range 0.5-2 km) and large (range 70-140 km) spatial scales using univariate and multivariate statistical approaches. Reclassification accuracy rates obtained from linear discrimination function analyses using both morphology and chemistry of otoliths were 61% and 82% for short and large spatial scales, respectively. No clear separation for individuals collected in islands within the Tamboretes Archipelago were observed suggesting that water masses are relatively homogeneous and/or that individuals could be highly mixed over short spatial scales. However, the higher reclassification success of the individuals belonging to Bom Abrigo, Galheta and Paz islands, indicates a limited movement of adults between habitats, a larval retention mechanism or a self-recruitment process occurring at large spatial scales. [ABSTRACT FROM AUTHOR]

While the number of species is a key indicator of ecological assemblages, spatial conservation priorities solely identified from species richness are not necessarily efficient to protect other important biological assets. Hence, the results of spatial prioritization analysis would be greatly enhanced if richness were used in association to complementary biodiversity measures. In this study, geographic patterns in estuarine fish species rarity (i.e. the average range size in the study area), endemism and richness, were mapped and integrated to identify regions important for biodiversity conservation along the Brazilian coast. Furthermore, we analyzed the effectiveness of the national system of protected areas to represent these regions. Analyses were performed on presence/absence data of 412 fish species in 0.25° latitudinal bands covering the entire Brazilian biogeographical province. Species richness, rarity and endemism patterns differed and strongly reflected biogeographical limits and regions. However, among the existing 154 latitudinal bands, 48 were recognized as conservation priorities by concomitantly harboring high estuarine fish species richness and assemblages of geographically rare species. Priority areas identified for all estuarine fish species largely differed from those identified for Brazilian endemics. Moreover, there was no significant correlation between the different aspects of the fish assemblages considered (i.e. species richness, endemism or rarity), suggesting that designating reserves based on a single variable may lead to large gaps in the overall protection of biodiversity. Our results further revealed that the existing system of protected areas is insufficient for representing the priority bands we identified. This highlights the urgent need for expanding the national network of protected areas to maintain estuarine ecosystems with high conservation value. [ABSTRACT FROM AUTHOR]

Aim Sea-level changes and coastal geomorphology (extension of continental shelves) have affected the pattern of diversification of brackish/freshwater fish populations due to the confluence of basins/estuaries during low sea-level periods (opportunity) and isolation during high sea-level periods. It is hypothesized that populations from estuaries in extensive continental shelves, which have greater potential for confluence, should have more opportunities for gene exchange than those in narrow continental shelves. To test this, we assessed the distribution of the genetic diversity and the patterns of diversification of the estuarine silverside, Atherinella brasiliensis, from the Brazilian coast. Location Eight estuaries along the southern and north-eastern portions of the Brazilian coast. Materials and methods Sequences of the mitochondrial control region (D-loop) and the cytochrome B were used to assess the distribution of genetic diversity, and these mitochondrial fragments and two nuclear introns were used to assess the patterns of diversification of A. brasiliensis. The palaeochannels that were exposed along the Brazilian coast during the Last Glacial Maximum were reconstructed using bathymetry data and the GIS method. Results The populations of A. brasiliensis from the estuaries of the north-eastern Brazilian coast (narrower and shallower continental shelf) showed higher levels of genetic differentiation and larger (more haplotypes) endemic lineages than the populations in the southern coast (broader and deeper continental shelf). Furthermore, south coast lineages showed more evidence of genetic exchange among populations, which have resulted in a reticulated relationship between lineages and estuaries. The reconstruction of palaeochannels revealed more connections among southern than north-eastern basins. Main conclusions Our results support the hypothesis that continental shelf extension and sea-level changes have influenced the diversification of A. brasiliensis. By extension, they also support the hypothesis of diversification by taxon pulse, which makes predictions based on the opportunities for expansion during periods of low sea level and the width of the continental shelf. We suggest this as a model for the genetic diversification and distribution of estuarine species along the Brazilian coast and other regions of the world. [ABSTRACT FROM AUTHOR]

Red and black groupers are large-bodied opportunistic ambush predators commonly found in Southwestern Atlantic tropical reefs. We investigated the diet of both species in order to detail ontogenetic, spatial and temporal trends, and to assess the extent of overlap in resource use between these two sympatric predators on the Abrolhos Bank, Brazil. Decapods and fishes were the main food items of Epinephelus morio while fishes were the main prey of Mycteroperca bonaci. Both diets were significantly influenced by body size and habitat, but only smaller individuals of E. morio feed almost exclusively on crustaceans. While the two groupers rely on many of the same prey types, coexistence may be facilitated by E. morio feeding more heavily on crustaceans, particularly the blackpoint sculling crab Cronius ruber, while black grouper take comparatively few crustaceans but lots of fish prey. Predators like red and black groupers could trigger indirect effects in the community and influence a large range of ecological processes, such as linkages between top and intermediate predators, and intermediate predators and their resources. [ABSTRACT FROM AUTHOR]

In response to concerns over wastage and negative impacts on stocks, the damage (antennae loss) and collateral mortality of artisanally trawledand- discarded juvenile seabob shrimp (Xiphopenaeus kroyeri) and the key factors explaining variability were assessed in the South Brazil Bight. During 20 deployments across 7 d of fishing, 1562 X. kroyeri (14.5±3.1 mm carapace length, CL) were discarded into replicate on-board tanks at both the start and end of sorting, with some individuals monitored immediately for antennae loss and mortalities, and the rest assessed after 3 h. Virtually, all X. kroyeri discarded towards the end of sorting (mean±SD air exposure of 15.9±3.9 min) died. By comparison, those discarded at the start (2.7±2.8 min) had variable temporal mortalities (total of 52.3% immediately vs. 66.2% after 3 h) which, like antennae loss (total mean±SE of 50.4±34.2%) were positively associated with haul duration/catchweight and deck exposure, and more frequent among individuals with soft than hard exoskeletons. Antennae losswas also negatively correlated with CL. The results support (i) improving trawl selectivity to reduce the catches of small, unwanted X. kroyeri and other bycatch (and therefore total weights of catches) and/or (ii) sorting catches in water (to minimize air exposure). Such modifications might be promoted through awareness of the potential harvest benefits to fishers associated with reducing unaccounted fishing mortality of the targeted species. [ABSTRACT FROM AUTHOR]

We assessed the local and species contributions to beta diversity, as well as its relationships with environmental and spatial drivers along the eastern Brazilian coast. Using abundance-based indices, total beta diversity was partitioned into "Local Contribution to Beta Diversity" (LCBD) and "Species Contribution to Beta Diversity" (SCBD) components at two levels (estuarine-coastal systems; estuarine and coastal areas). Furthermore, we evaluated the relationships between LCBD values and local environmental conditions and spatial structures, in addition to fish assemblage metrics. Our results indicated that LCBD values were higher in the estuarine areas compared to their adjacent coastal areas and primarily associated with lower salinity and depth, and higher temperatures. Spatial effects were indicative of higher local uniqueness related to unmeasured large-scale processes. Sites with higher species diversity and lower dominance had higher LCBD, while species richness had slight positive influence on LCBD at both levels. The contributions of species varied within and between levels, but the highest SCBD values were supported primarily by common and dominant species. Our study highlights the importance of the environmental conditions provided by estuarine areas for the overall variation of fish assemblages. • Estuaries exhibited higher local contributions to total beta diversity. • Highest SCBD values were supported primarily by common and dominant species. • The LCBD was a primary result of local environmental conditions. • Sites with higher species diversity and lower dominance had higher LCBD. • Environmental and spatial effects on LCBD reinforced the importance of multiscale assessments. [ABSTRACT FROM AUTHOR]

An important objective of fish ecology is to understand pure and shared effects of abiotic, biotic, and spatial predictors of fish assemblages' structure on continental shelves. This study aims to assess the structure of the bottom-associated fish assemblage on the shallow inner continental shelf of Paraná, southern Brazil, in response to physicochemical, biological, and spatial factors. We hypothesize that this structure is associated with the benthic megafauna, particularly with the distribution of the Brazilian seabob shrimp Xiphopenaeus kroyeri , an abundant fishing resource on the shallow coast of Paraná. We used uni and multivariate analyses to examine the distribution of abundance, richness, and composition of ichthyofauna in the region. Using variance partitioning analysis, we determined the pure and shared effect of spatial (latitude and longitude), physicochemical, and spatiotemporal distribution patterns of crustaceans, echinoderms, and mollusks as potential predictors of the structure of the fish assemblage. The data were obtained monthly from a one-year bottom trawl survey, comprising five transects and four depths (six, nine, 12 and 15 m) in a 60 km long section of the inner continental shelf, under the influence of estuaries. We captured 57578 demersal fish, comprising 37 families and 88 species. The average abundance of fish per haul was 387 individuals at a depth of 6 m, decreasing to 114 individuals per haul at 15 m. Average richness also decreased along the bathymetric profile, from 15 to 10 species per haul. Fish abundance and richness responded positively to a seasonal estuarine discharge pattern that was stronger in summer and autumn. High biomass of juvenile seabob shrimp in shallower regions also explained the higher abundances and richness. The results also suggest the existence of two fish assemblages in the region, associated with the distribution of the megafauna and segregated by depth, water surface transparency, and sediment particle size composition. Despite significant seasonal variations, controlled by precipitation and bottom water temperature, the structure of fish assemblages responded to the pure and shared effects of the three predictive components in all seasons. In particular, local coastal hydrography and the prey-predator relationship between fish and seabob shrimp were ecologically relevant processes for structuring fish assemblages at the inner continental shelf of Paraná. This study highlights the complexity of ecological interactions within demersal fish assemblages and the importance of considering biotic and abiotic factors in understanding fish distribution patterns at the spatial scale of inner continental shelves that are influenced by estuaries. [Display omitted] • Variance partitioning shows pure and shared effects of spatial, biotic, and abiotic predictors on fish assemblage structure. • Two fish assemblages segregated by depth, transparency, sediment size, and megabenthos at the inner continental shelf scale. • Coastal hydrography and prey-predator relationship are ecologically relevant for structuring fish assemblages. [ABSTRACT FROM AUTHOR]

A large number of fish species use the mangrove mainly due to food availability and protection against predators. The knowledge of temporal and spatial dynamics of ichthyofauna allows us to identify patterns of occupation of this ecosystem and to support the assessment and preservation of local biodiversity. In this sense, samplings were conducted in 1988 at five areas of the Itacorubi River estuary, Santa Catarina Island. A total of 3,883 specimens were collected, distributed in 21 families and 41 species with the predominance of Cetengraulis edentulus, Mugil liza, Mugil curema, Genidens genidens, Mugil gaimardianus, Eucinostomus gula, Micropogonias furnieri, Pomatomus saltatrix and Sphoeroides testudineus. On average, abundances differed between seasons and sampled areas. Differences were detected between the fish faunas of fall and winter compared to summer and spring and between sampling sites. This study identified a fish assemblage in the mangrove of the Itacorubi River with a similar structure to other estuaries of southern Brazil. [ABSTRACT FROM AUTHOR]

A single Pomacanthus maculosus was filmed during a scuba diving survey on a rocky reef from southern Brazil. The body shape and coloration pattern confirmed the species identification. The biological and ecological characteristics of P. maculosus and the long distance of Brazil from its original distribution strongly suggest of an anthropogenic pathway of dispersion. [ABSTRACT FROM AUTHOR]

Within the Brazilian province, rocky reefs and submerged outcrops are among the most important habitats for reef fishes, providing suitable habitats for the development of reef fish communities and consequently sheltering a high ecological diversity. Rocky reef fish assemblages were sampled in seven coastal islands in South Brazil by strip transects of 40 m² by the underwater visual census to obtain density (fish 40 m-2) and biomass (g 40 m-2). Fish species were also categorized according to trophic category and geographical distribution. In total, 526 strip transects were performed, covering an area of 21,040 m², providing 19,377 fish, distributed among 73 species of 34 families. Itacolomis Island presented the highest density, followed by Veado Island. Regarding biomass, Itacolomis Island and Pedra da Baleia were the most representative rocky reefs. Mobile invertebrate predator was the trophic category with the highest density and biomass. A total of 60% of the species occur in the Western Atlantic, 20% are Transatlantic and 9.6% are endemic to the Brazilian Province. Our results indicate that despite the similarity in the taxonomic composition among islands, the observed differences in densities and biomass, highlight singular assemblage structures, whether by environmental and/or anthropogenic factors, and dominated by few species, both in density and biomass. [ABSTRACT FROM AUTHOR]

Abstract: As part of attempts to improve and promote acceptance of the Nordmøre-grid in a Brazilian artisanal penaeid canoe-trawl fishery, the effects of bar spaces on the catches of key teleosts and crustaceans were investigated. Compared to a traditional codend, three Nordmøre-grids comprising 24-, 20- and 17-mm bar spaces, respectively, significantly and incrementally reduced the total weight of unwanted brachyurids (by 75, 95 and 97%), without affecting the catches of targeted seabob shrimp (Xiphopenaeus kroyeri). The various grids had few significant impacts on the catches of any teleosts; attributed to their small sizes and species-specific differences in behavioural responses. The results confirm the utility of the Nordmøre-grid for addressing a key bycatch concern among local fishers, and provide insight into ongoing development of appropriate modifications to improve selectivity in this, and other regional fisheries. [Copyright &y& Elsevier]

The relative efficiency of two square-mesh codend designs with the same circumference (~2 m) but different mesh sizes and materials (32 mm polyethylene-PE and 30 mm polyamide-PA) was tested in an artisanal shrimp trawl fishery in Paraná, southern Brazil. The two square-mesh codends were hauled alternately with a 26 mm diamond-shaped mesh codend (control) in a twin gear configuration. Although not significant, the mean numbers of total bycatch were reduced by 16.6 and 10.0% with the 32 and 30 mm square-mesh codends, respectively. The results indicate significant improvement in size selectivity for some species (Xiphopenaeus kroyeri and Stellifer rastrifer). The operational changes tested can be a suitable technical solution for reducing the capture of immature organisms in the shrimp trawl fishery in Paraná, Brazil. [ABSTRACT FROM AUTHOR]

Abstract: Two experiments were done to assess and refine the Nordmøre-grid in a canoe-trawl fishery targeting Xiphopenaeus kroyeri off southern Brazil. During experiment 1, a codend containing a small (1881cm2) Nordmøre-grid (24-mm bar spaces) retained significantly less total bycatch (mean predicted weight reduced by 56%), brachyurids (by 79%) and teleosts (by 50%) than a conventional configuration (control), without significantly affecting the weights or numbers of X. kroyeri, although mean predicted weights were 12% lower. During experiment 2, the bar spaces were subsequently maintained, but the grid area was increased by 1.4 while the extension section mesh size was reduced by 1.3, and the impacts of different materials (hollow vs. solid aluminium rod), bar diameter (10 vs. 16mm) and presence/absence of a guiding panel were investigated. Most of these technical changes had minimal effects, with all grid configurations maintaining catches of X. kroyeri (at between −13 and +22% of the control) and significantly reducing total bycatch (up to 54%) and brachyurids (up to 90%). But, unlike the small grid, none of the large grids significantly reduced the catches of teleosts. This result was attributed to the increased distance required by fish smaller than the bar spaces to swim out of the escape exit. While ongoing refinements, including narrower bar spaces, could improve the performance of the Nordmøre-grid, the results justify the adoption of the generic configuration as a means for improving selectivity in this fishery. [Copyright &y& Elsevier]