Márcia Cristina Costa de Azevedo

Environmental influences on the demersal fish assemblages in the Sepetiba Bay, Brazil

The structure of the demersal fish assemblage in Sepetiba Bay, southeast Brazil (22°54′–23°04′S, 43°34′–44°10′W) was described and related to environmental variables. A 3-yr long trawl survey (from July 1993 to June 1996) was conducted using a stratified random sampling strategy at 158 stations. One hundred and seven species of fishes in 80 genera and 44 families were identified. Gerreidae and Ariidae made up 30.5% and 28.6%, and 19.8% and 28.1% of the total number and weight, respectively. Sciaenidae, Engraulididae, Sparidae, and Carangidae were other prominent families. Three assemblages existed in the bay: one inhabited shallow, less saline and less transparent water in the inner zone (depth <5 m, transparency <2 m, salinity <30 psu, and slightly higher temperature); another in the outer zone with the opposite situation (depth >10 m, transparency >3 m, salinity >30 psu, and slightly lower temperature); and a third assemblage in the middle zone likely to prefer average values or show no clear preferences. Most species decreased in abundance over the 3-yr period of study. No seasonal change was detected in the assemblage structure, but many species were rare, indicating high spatial and temporal patchiness. Canonical correlation analyses were used to describe and compare the fish assemblages in the three different habitats. The outer zone had the greatest number of species recorded, lowest abundance, highest diversity and evenness, and was comprised mainly byCynossion leiarchus, Prionotus punctatus, Anchoa tricolor, Haemulon steindachneri, Diplectrum radiale, Etropus crossotus, andSphoeroides greeleyi; the inner zone had the lowest number of species recorded but the greatest number of species per sample, highest abundance, lowest diversity and evenness, being comprised mainly byDiapterus rhombeus, Genidens genidens, Cathrops spixii, Chloroschombrus chrysurus, Sciadeichthyes luniscutis, Cetengraulis edentulus, andArchorsargus rhomboidalis; while the third group had the lowest number of species per sample, being comprised by species widely distributed asGerres aprion, G. genidens, Gerres gula, andMicropogonias furnieri. Depth, followed by transparency and salinity, were the primary factors influencing assemblage distribution.

Estrutura da comunidade de peixes demersais da baía de Sepetiba, RJ

Um programa de amostragens mensais de arrasto de fundo em sete estacoes de coleta na Baia de Sepetiba foi realizado entre julho de 1993 e junho de 1994 com o objetivo de descrever a estrutura da comunidade de peixes e suas variacoes espaciais e temporais. Noventa e sete especies de peixes foram levantadas, compreendendo 70 generos e 38 familias. As familias Ariidae, Gerreidae, Sciaenidae, Carangidae e Sparidae, nesta ordem, foram as mais abundantes em numero, contribuindo com 69,9% do total capturado, enquanto Ariidae, Sparidae, Gerreidae, Haemulidae e Sciaenidae somaram 67,9% do peso total. Genidens genidens, Gerres aprion, Cathorops spixii, Micropogonias furnieri e Chloroscombrus chrysurus, nesta ordem, foram as especies mais abundantes, contribuindo cada uma com mais de 5% do numero total de peixes capturados. O maior numero de peixes foi associado as menores profundidades e transparencias, enquanto a salinidade apresentou, na maior parte do tempo, valores estaveis em torno de 29%o. Maiores abundâncias de peixes ocorreram entre fins do verao e inicio do inverno. O numero e peso dos peixes foram maiores na zona interna da Baia enquanto o numero de especies foi maior na zona externa, proxima ao limite com o mar. O elevado numero de especies de peixes sugere o importante papel da Baia de Sepetiba como area de criacao e desenvolvimento para a comunidade de peixes.

Variações temporais e espaciais na composição e estrutura da comunidade de peixes jovens da Baía de Sepetiba, Rio de Janeiro

A year-long beach seine survey at the continental margin of Sepetiba Bay, Rio de Janeiro State, Brazil, catching mainly young-of-the-year and juvenile fishes was carried out from July 1983 to June 1984, in order to describe the community structure and their spatial and seasonal variations. Fifty-five monthly samplied carried out in five sites in the marginal surf zone waters yielded 11,463 fishes in 82 species, 59 genera and 31 families. Gerreidae, Engraulidi-dae, Atherinidae and Ariidae families amounted 87.01% of the total catch in number, and 81% in weight. Cerres aprion Cuvier, 1829, Anchoa januaria (Steindachner, 1879), Anchoviella lepidentostole (Fowler, 1911), Atherinella brasiliensis (Quoy & Gaimard, 1824) and Neluma barba (Lacepede, 1803) were the most numerous species, each one contributing more the 4% of total catch. Overall, both spatial and seasonal changes in fish were not evident although most individuais were more abundant in the outer Bay. The high number of fish species in this area, suggest the important role played by the Sepetiba Bay in the fish community to where many species probably migrate from the nearby sea and stay in the Bay during part of their life cycle. Decreasing diversity and high dominance of a few number of species seem to indicated a trend of environmental deterioration in the Sepetiba Bay over the last decade, as this date are compared whith similar sampling program carried out in 1993/94. It same to indicated that changes in fish populations which use this area as rearing grounds, occurred during their early life history.

Biologia reprodutiva dos bagres marinhos Genidens genidens (Valenciennes) e Cathorops spixii (Agassiz) (Siluriformes, Ariidae), na Baía de Sepetiba, Rio de Janeiro, Brasil

The reproductive cycle of the marine catfishes Genidens genidens Valenciennes, 1833 and Cathorops spixii Agassiz, 1839 in the Sepetiba Bay, was assessed by an annual period of sampling from October 1993 to September 1994. The fishes were caught by standardized otter trawl and environmental parameters of temperature, salinity and transparency of water were recorded at each sampling. Five gonadal phases were described, based in macroscopic observations. Changes in the gonadosomatic index (GSI) and in the percentual of stages of gonadal development showed that G. genidens spawns in Summer/early Autumn, coinciding with low salinity and high temperature and transparency. Cathorops spixii spawns in late Spring/early Summer, coinciding with rising temperature and transparency and low salinity. Total spawning are shown for both species, as indicated by length-frequency of oocytes per stages of maturation with two groups synchronic development of oocytes. Fecundity is low (10-23 oocytes, for G. genidens and 24-30 for C. spixii), when compared with other teleosteans, and was not strongly correlated to the total length (G. genidens, r=0.65, C. spixii, r=0.76). Strategy-k is developed by both species as indicated by high brood and enbrions protection and high body length.

Estratégia trófica dos linguados Citharichthys spilopterus Günther e Symphurus tessellatus (Quoy & Gaimard) (Actinopterygii, Pleuronectiformes) na Baía de Sepetiba, Rio de Janeiro, Brasil

The aim of this study was to assess the spatial and ontogenetic changes in diet of the flatfishes Citharichthys spilopterus Gunther, 1862 and Symphurus tessellatus (Quoy & Gaimard, 1824) in the Sepetiba Bay. The studied area was divided in three zones (inner, central e outer), where bottom trawls were performed during the day, from October 1998 to September 1999. Citharichthys spilopterus showed higher Indices of Relative Importance (IRI) for Mysidacea (0.3359) and Amphipoda (0.0805), while S. tessellatus showed the highest IRI for Amphipoda (0.7515) and Polychaeta (0.2586). The high percentage (67.61%) of empty guts in S. tessellatus suggests nocturnal feeding activity. Smaller sized individuals (TL 115 mm) fed on Polychaeta the inner zone, Gobiidae in the central and Decapoda in the outer. The smaller individuals (TL 155 mm) fed on Polychaeta in the inner zone, and Amphipoda and Polychaeta in the outer zone. Citharichthys spilopterus, shows comparatively larger mouth and eye, and feed on organisms in the water column nearby, with a more specialized feeding habit, compared with S. tessellatus, which feed on organism on the substrate. Although the two species feed basically on Crustacea, they present low overlaping in the diet (0.197), and this is probably the trophic strategy developed to allow the coexistence of these two closely related species in the Bay.

Spawning season, recruitment and early life distribution of Anchoa tricolor (Spix and Agassiz, 1829) in a tropical bay in southeastern Brazil

The pattern of the use of the Sepetiba Bay, a semi-closed 450 km(2) area in southeastern Brazil, by Anchoa tricolor was investigated to assess spawning period, recruitment and to detect spatial-temporal patterns of this major fishery resource. Fishes were sampled by seine nets, from spring, 1998 to winter, 1999 and by beach seine, from spring, 1998 to winter, 2000. Reproductive season, measured in terms of GSI, gonad development and appearance of recruits, indicate that reproduction occurs from August to March, when they reach the best condition. Recruitment peaks in winter/spring at sandy beaches where they stay until late summer, moving toward deeper bay areas during autumn. After that, they join adults and perform movements between the bay and the adjacent continental shelf to reproduce.

Inter-annual changes in fish communities of a tropical bay in southeastern Brazil: What can be inferred from anthropogenic activities?

We assessed inter-annual changes in fish assemblages of a tropical bay which experienced a heavily industrialized process in the last decades. A highly significant difference in community structure among the bay zones, and a decrease in fish richness and abundance over time were found. Changes in fish richness and abundance between the two first (1987-1988 and 1993-1995) and the two latter time periods (1998-2001 and 2012-2013) were sharpest in the inner bay zone, the most impacted bay area, and in the middle zone, whereas the outer zone remained comparatively stable over time. These changes coincided with increased metal pollution (mainly, Zn and Cd) in the bay and with the enlargement of the Sepetiba Port. Spatial changes in the fish community structure among the bay zones were related to differences in salinity, transparency and depth with this latter variable acting as a buffer stabilizing temporal community changes.

Seasonal changes and spatial variation in the water quality of a eutrophic tropical reservoir determined by the inflowing river

Abstract The water quality of a eutrophic tropical reservoir was studied over a 5-year period (2000–2004), with quarterly sampling (Jan, Apr, Jul, and Oct) carried out at 3 sampling stations with one station in each of 3 zones (fluvial, transitional, and lacustrine). During the wet season, large amounts of phosphorus were introduced into the reservoir by the increased inflow of the river. Dissolved oxygen, pH, and chlorophyll a levels peaked in the wet season; pH, chlorophyll a, and total phosphorus in several cases were recorded above the recommended Brazilian guidelines. Dissolved oxygen was lower than acceptable levels in the euphotic layer and reached very low levels in the hypolimnion, indicating thermal stratification. Efficient reservoir management is necessary to restore environmental quality, and our results indicate that selective withdrawal may be an effective means of improving the quality of water in Funil Reservoir.

Shifts in the abundance and distribution of shallow water fish fauna on the southeastern Brazilian coast: a response to climate change

The temperature in the South Atlantic underwent an increase from 1948 to 2016, and the Brazilian coast is very likely suffering from climate change. We examined temporal shifts in the abundance of the fish fauna that inhabit shallow waters and aimed to associate these shifts with climate effects. We selected candidate species according to changes in their relative abundance over four decades (1980s, 1990s, 2000s, 2010s) in a transition area between the tropical and subtropical regions in southeastern Brazil. Forty-seven species exhibited changes in abundance during the study period. Several small pelagic/planktophagous clupeoids (Anchoa lyolepis, Anchoa tricolor, Harengula clupeola, and Sardinella brasiliensis) reacted strongly to climate change with rapid population growth, whereas others (Anchoa marinii, Anchoviella brevirostris, Anchoviella lepidentostole, and Lycengraulis grossidens) decreased in relative abundance or disappeared. Some tropical species appear to be moving to this transition zone (e.g., Achirus lineatus, Ctenogobius boleosoma, and Haemulopsis corvinaeformis) because they appeared or increased populations. Conversely, subtropical species (e.g., Genidens barbus, Platanichthys platana, Boridia grossidens, and Trachinotus falcatus) decreased populations or disappeared, probably moving southward to more favorable areas, consistent with warming. This is the first estimation of climate change impacts on the southwestern Atlantic nearshore fishes and contributes as support for management policies.