Citharichthys Spilopterus Research Articles

Metal bioavailability and distribution in the fish community in a tropical estuary, Sepetiba Bay, Rio de Janeiro, Brazil

Sepetiba Bay has a wealth of fish species (total 148) as well as a vast area of mangroves and numerous rocky islands, which are important sites of reproduction for marine life. This peculiar environment of the Brazilian coast hosts one of the most important industrial centres of south-eastern Brazil. This site has been impacted for decades by the release of industrial emissions and effluents with high metal loads by the steel industry. The ranges of metal concentrations in fish muscle from the species Micropogonias furnieri, Genidens genidens, Cathorops spixii, Notarius grandicassis, Diapterus rhombeus, Selene vomer, Prionotus punctatus, Citharichthys spilopterus, Achirus lineatus, Trinectes paulistanus, Symphurus tessellatus and Hypanus guttatus were measured (Al: 0.02-555.9 µg g-1 d.w., As: 0.0002-20.1 µg g-1 d.w., Cd: <0.0002-0.2 µg g-1 d.w., Cu: 0.2-2.3 µg g-1 d.w., Fe: <0.02-244.9 µg g-1 d.w., Zn: 0.5-227.3 µg g-1 d.w. and Pb: <0.001-1.3 µg g-1 d.w.). The Kruskal-Wallis test revealed significant differences (p<0.05) in the As, Cu, Fe, Pb and Zn contents among fish species. The monitoring of suspended particulate matter during dredging operation revealed the mean metal values for Al (6059±6268 µg g-1), Cd (0.2±0.5 µg g-1), Cu (29±29 µg g-1), Zn (332±892 µg g-1), and Pb (52±70 µg g-1). The results of bioaccumulation in fish calculated from the bioavailable sediment fractions and suspended particulate matter showed lower values than those in fish muscle. Arsenic was found at levels above the maximum limit for human consumption according to Brazilian legislation. However, the estimated probability and risk of metal intake via fish consumption showed that the consumption of all species presented low risk.

Flatfish Habitat Use of a Small Southeastern US Tidal Creek: Long- and Short-term Occupancy Patterns

Many flatfish species utilize coastal areas during at least one of their life-history stages. Estuaries on the eastern US Atlantic coast provide important settlement and nursery habitat for flatfishes. Small tidal creeks serve as transition zones between upland and estuarine environments and are a consistent settlement and nursery habitat for flatfish. Flatfish habitat use in Wylly Creek, a southeastern US tidal creek, was examined to determine whether assemblage composition has changed over a decadal time period (2004–2007 vs. 2016–2019). In addition, the potential effect of cold winters on juvenile flatfish recruitment and subsequent spring flatfish assemblage composition were examined. Flatfish assemblages have undergone subtle shifts in composition between initial and recent time periods, with decreases (5–16-fold) in abundance occurring for ocellated flounder Ancylopsetta quadrocellata, summer flounder Paralichthys dentatus, and southern flounder Paralichthys lethostigma, while abundances of more common species, bay whiff Citharichthys spilopterus and blackcheek tonguefish Symphurus plagiusa, remained relatively consistent. Bay whiff recruitment into the creek occurred in early spring, but was delayed in most years with colder winters. Minimum residency for bay whiff within an approximately 350 m stretch of creek was estimated to be approximately 5–10 days. Flatfish habitat use in this small tidal creek adjacent to a relatively undeveloped coastal area may reflect a shifting baseline against which potential assemblage shifts in developed areas can be assessed.

Seasonal and Interannual Variability in Flatfish Assemblages in a Southeastern USA Estuary

Although salt marsh tidal creeks are among the shallow coastal and estuarine habitats important to juvenile fish, little is known about the temporal patterns of their use by flatfish in the southeastern USA. We used a 12-year monitoring study to examine seasonal and interannual variation in juvenile flatfish occupation of a salt marsh tidal creek. Fishes were collected monthly with a 1-m beam trawl during the middle of ebbing tide near Savannah, GA. Flatfishes were the most consistently collected and numerous species obtained; we rarely obtained other fish in high number except for an occasional recruitment pulse of sciaenids. The six flatfish species collected were blackcheek tonguefish Symphurus plagiusa, bay whiff Citharichthys spilopterus, fringed flounder Etropus crossotus, summer flounder Paralichthys dentatus, southern flounder Paralichthys lethostigma, and ocellated flounder Ancylopsetta quadrocellata. Bay whiff was the only species consistently collected as new recruits (< 20 mm TL), accounting for 83% of all recruits obtained in the study. Flatfish were collected year-round, with bay whiff numerically dominating winter and spring assemblages and blackcheek tonguefish dominant in summer, leading to differences in seasonal assemblages. Flatfish assemblage composition did not exhibit a consistent trend across years but was related to temperature variation. For instance, flatfish assemblages collected in springs that followed unusually cold winters differed from those that followed mild winters, contributing to interannual variation in habitat use. Bay whiff growth was positively related to temperature, but was not related to the densities of conspecifics or total flatfish. Estuarine tidal creeks provide important settlement and nursery habitat for flatfish that partition habitat use temporally via seasonal and interannual variation, and these fishes can consistently dominate the composition of ichthyofaunal benthic recruits.

Interference of heavy metals present in the water of the Lagoa Tramandaí/RS on the carbohydrate metabolism of the GURI Sea Catfish (G. genidens) and Bay whiff (C. spilopterus)

This study aims to evaluate the contamination of the water of Lagoa Tramandaí on Genidens genidens and Citharichthys spilopterus residents of Lagoa Tramandaí, a region susceptible to environmental damage due to the release of domestic sewage from the municipalities bathed by the lagoon. Thereby, the biota suffers the interference of heavy metals, affecting their behavior and the metabolism of these individuals. The hepatic and muscular glycogen, glucose and plasma lactate of these species were analyzed, as well as the presence of heavy metals in lagoon water. When the species were analyzed separately with their controls, both mobilized more glycogen than the control and presented increased glucose and lactate, which is characteristic of animals contaminated by heavy metals. When compared with each other, they showed differences regarding carbohydrate metabolism. It was observed that the Guri Sea Catfish suffers more influence of heavy metals than the Bay whiff. Thus, we can conclude that the water contaminated with heavy metals of this lagoon interferes in the carbohydrate metabolism of both species of fish.

Fish Predation on Juvenile Penaeid Shrimp: Examining Relative Predator Impact and Size-Selective Predation

Predation is likely the primary source of mortality for juvenile penaeid shrimp and, therefore, a key factor driving their population dynamics. We sampled juvenile penaeids and their potential predators in a salt marsh from July to August 2012 to examine the impact of these predators and possible size-selective predation on the shrimp population. We quantified predator impact using the frequency of occurrence (FO) index and a relative predation index (RPI) that accounts for predator abundance and the number of shrimp consumed per individual predator. Size selectivity was assessed by comparing the size distribution of shrimp in the study area to the size distribution of shrimp removed from predator stomachs. Two penaeid species, white shrimp Litopenaeus setiferus and brown shrimp Farfantepenaeus aztecus, were collected, and most (86%) were juvenile white shrimp ≤ 12 mm carapace length. Spotted seatrout Cynoscion nebulosus, which consumed relatively large shrimp, was the most important predator based on the FO index. Bay whiff Citharichthys spilopterus, which ate the smallest shrimp, was the most important predator based on the RPI. The size distribution of shrimp removed from predator stomachs differed from those collected in the study area; the smallest shrimp were disproportionally more abundant in predator stomachs. Using the RPI, we identified some potentially important predators (e.g., bay whiff) that may impact shrimp populations by consuming the smallest shrimp in estuarine nurseries. Our approach could be useful for examining predator impacts on other populations of juvenile penaeids and more generally for any prey consumed by fish predators.

Fish assemblages in a coastal bay adjacent to a network of marine protected areas in southern Brazil

Abstract Baía Norte (North Bay) in Santa Catarina State is considered a typical coastal bay and is surrounded by a network of Marine Protected Areas. The objectives of this study were to describe the composition of the demersal fish assemblage, identify seasonal and spatial structures on a fine scale and evaluate the role of habitat descriptors and abiotic variables affecting the fish assemblage structure. Seasonal samplings were conducted in 2005, using bottom trawls in six pre-established areas in Baía Norte in summer, fall, winter and spring. Simultaneously with each trawl, environmental data were collected with a multiparameter probe. Temporal and spatial differences in fish abundance were tested by a PERMANOVA. To illustratethe differences detected graphically we ran a canonical analysis of principal coordinates (CAP). The influence of environmental variables on the fish fauna was evaluated using a Distant Based Linear Model (DistLM) with Akaike's information criterion (AIC). A total of 9,888 specimens, distributed in 27 families and 62 species, were collected. Citharichthys spilopterus was the most abundant species. PERMANOVA detected differences for abundance between seasons, areas and interaction among all the factors. The DISTLM selected temperature and pH. The results highlight seasonality as an important factor in the structuring of fish fauna of the study place.

The influence of oceanographic conditions on the spatial and temporal patterns of Pleuronectiforms larvae (Teleostei) in the equatorial Atlantic Ocean

ABSTRACT In this study, we analyzed the composition, distribution and abundance of Pleuronectiform larvae in relation to abiotic factors (temperature and salinity) and biotic factors (phytoplanktonic and zooplanktonic biomass) in the equatorial Atlantic Ocean. The working hypothesis was that the composition and distribution pattern of Pleuronectiform larvae species present differences between the areas studied according to the hydrographical environment/factors analyzed. Ichthyoplankton was collected during Period: 1 (August - October 1995), 2 (January - April 1997), 3 (April - July 1998) and 4 (September - December 2000), in the equatorial Atlantic Ocean. We examined 562 Bongo-net (500 μm) samples that contained 719 Pleuronectiform larvae belonging to three families: Bothidae (Bothus ocellatus and Engyophrys senta), Paralichthyidae (Syacium papillosum, Citharichthys spilopterus and Citharichthys sp.) and Cynoglossidae (Symphurus sp.). The Pleuronectiform larvae accounted for 4% of total fish larvae and occurred at 37% of the oceanographic stations. B. ocellatus was the species with the highest relative abundance (70%), the greatest value occurring during Period 3 (77%), whereas the lowest relative abundance (57%) was recorded in Period 1. S. papillosum was the species presenting the second highest relative abundance (14%), with higher values during periods 1 and 4. The results demonstrated that environmental factors influence the distribution and abundance of Pleuronectiform larvae so that each species occurs in a more favourable period and place for spawning and growth. B. ocellatus was related to warmer waters and greater phytoplanktonic and zooplanktonic biomass, while S. papillosum occurred in saltier waters and at lower temperatures.

Fecundity of fishes inhabiting coastal and estuarine environments in the southwest Atlantic Ocean

ABSTRACTThe aim of this study was to estimate the fecundity of six marine fish species from the southwest Atlantic off the coast of São Paulo State, Brazil. In particular, the number of oocytes in the most advanced vitellogenic stage (NDO), batch fecundity and the number of batches that will be produced were estimated. Specimens of longfinger anchovy Anchoa filifera, atlantic anchoveta Cetengraulis edentulus, bay whiff Citharichthys spilopterus, Stellifer brasiliensis, rake stardrum S. rastrifer and southern kingcroaker Menticirrhus americanus were captured bimonthly, from June (2012) to May (2013). The mature ovaries were removed, weighed, fixed in formalin solution and histologically analysed. All histological sections were photographed and the images analysed using advanced image processing techniques. The estimated number of batches that will be recruited to the germinal vesicle migration/hydrated stock ranged from one to four batches. NDO is positively related to ovarian and female size. Small females with low ovary weight produce low NDO. The NDO in A. filifera, C. edentulus and M. americanus may represent the final number of oocytes to be spawned in the next spawning event, which could be used for batch fecundity estimation. This study contributes to a better understanding of the reproduction of species inhabiting shrimp fishery grounds which are caught as by-catch in tropical and subtropical ecosystems. Information on the maturity and fecundity of these populations is an important element in assessing stock status and the degree of fishing pressure these populations are experiencing.

A Modeling and Field Approach to Identify Essential Fish Habitat for Juvenile Bay Whiff (Citharichthys spilopterus) and Southern Flounder (Paralichthys lethostigma) Within the Aransas Bay Complex, TX

The goal of this study was to use an ecosystem-based approach to consider the effect of environmental conditions on the distribution and abundance of juvenile bay whiff and southern flounder within the Aransas Bay Complex, TX, USA. Species habitat models for both species were developed using boosted regression trees. Juvenile bay whiff were associated with low temperatures ( 10, and moderate to high dissolved oxygen (6–9 mg O2/l, 10–14 mg/l). Juvenile southern flounder were associated with low temperatures ( 8 mg O2/l). Our results indicate that conservation measures should focus along the eastern side of Aransas Bay and the north corner of Copano Bay to protect essential fish habitat. These findings provide a valuable new tool for fisheries managers to aid in the sustainable management of bay whiff and southern flounder and provide crucial information needed to prioritize areas for habitat conservation.

A ictiofauna do Canal de Bertioga, São Paulo, Brasil

O Canal de Bertioga, localizado no litoral do estado de São Paulo, é delimitado pelo continente e pela ilha de Santo Amaro, constituindo a unidade natural que conecta os municípios de Santos, Guarujá e Bertioga, representando uma segunda conexão do complexo estuarino de Santos-São Vicente com o oceano. No presente estudo foram realizadas coletas, entre dezembro de 2009 a novembro de 2010, no trecho norte do Canal de Bertioga (23° 51' 23,83" S e 46° 07' 58,87" O e 23° 53' 31,72" S e 46° 11' 17,74" O), com o objetivo de inventariar a ictiofauna da região. Foram coletados 1.429 exemplares, pertencentes a 78 espécies, incluídas em 14 ordens, 39 famílias e 67 gêneros. As famílias mais especiosas foram Sciaenidae (nove spp.), Carangidae (nove spp.), Haemulidae (sete spp.), e Ariidae (cinco spp.), e as espécies mais abundantes foram Stellifer rastrifer (n = 243), Harengula clupeola (n = 182), Cathorops spixii (n = 144), Oligoplites palometa (n = 109) e Mugil curema (n = 102), sendo que Achirus lineatus, Atherinella brasiliensis, Cathorops spixii, Chaetodipterus faber, Citharichthys spilopterus, Genidens genidens, Micropogonias furnieri e Stellifer rastrifer, ocorreram em todas estações do ano. Das espécies encontradas, seis foram reconhecidas constantes, 19 acessórias e 53 ocasionais. Em relação aos seus hábitos, 40 espécies são marinho-estuarinas, 26 marinhas, 11 estuarinas e uma de água doce, sendo 52 espécies demersais e 26 pelágicas. Onze espécies são relacionadas em listas de espécies ameaçadas. Adicionalmente, é apresentada uma chave de identificação para as espécies do trecho norte do Canal de Bertioga.

Spatial, diel, and seasonal changes in the fish community structure of a Mexican tropical estuary

To extend our knowledge about spatial and temporal variations in the structure of estuarine fish communities, diel samplings (collections every 2 h) were carried out every two months over a one-year period in two different habitats (vegetated and nonvegetated). We collected a total of 34,766 individuals, corresponding to 72 species, most of them with marine and tropical affinities. Species richness was significantly higher in the vegetated habitat, whereas abundance (number of fish) was higher in the nonvegetated habitat. The diel pattern of abundance showed peaks at dusk and dawn, whereas richness was higher at night. Seasonally, fish abundance and species richness showed peaks during January, March, and July–September, and these peaks were related to the entry of temperate species, production processes in the system, and rainfall pattern. Fish assemblages showed significant differences among habitats, day/night, and months. In the vegetated habitat, Lagodon rhomboides, Menidia beryllina, and Orthopristis chrysoptera were the predominant species. Microphagus species such as Brevoortia gunteri, Brevoortia patronus, and Mugil curema were predominant during the warm, dry season (March–May) and they were more abundant during the day. In contrast, predatory species such as Citharichthys spilopterus and Opsanus beta were more abundant during the rainy season and their capture was higher at night. The two most numerically abundant species, Anchoa mitchilli and Membras martinica, showed a twilight pattern, with abundance peaks at dusk and dawn, respectively. Hence, in Pueblo Viejo Lagoon (Mexico), the spatiotemporal changes in species composition are in part related to predator avoidance and feeding strategies, through a coupling of life histories with the diel and seasonal variation in the availability of resources, the presence of submerged vegetation playing an important role in this dynamic.

Spatial and temporal changes in the fish assemblage of a subtropical estuary in Brazil: environmental effects

This work provides information about the fish assemblage structure along the estuarine gradient of Baía da Babitonga, south Brazil. The seasonal and spatial dynamics of fish and their relationship with physical–chemical variables were investigated. A total of 70,085 fish of 70 taxa were collected. Late larva and early juveniles of Engraulidae, Eucinostomus spp. and Mugil spp. dominated in abundance, representing 62% of all fish captured. Permutational multivariate analysis of variance identified distinct fish assemblages within the bay and during the year. The marine straggler species Harengula clupeola, Oligoplites saliens and Trachinotus carolinus and the estuarine migrant Anchoa tricolor were characteristic of the outer-most bay area, while the estuarine resident and migrant species Atherinella brasiliensis, Anchoa januaria, Sphoeroides greeleyi and Citharichthys spilopterus, and the marine migrant Diapterus rhombeus were characteristic of the inner portion of the estuary. The seasonal changes in community structure observed were mainly related to the greater abundance of T. carolinus in the warm/wet season, Micropogonias furnieri in the transition season and Oligoplites saliens in the cold/dry season. Depth, followed by salinity, explained the greater part of the variability in the abundance of dominant species and was found to be important in shaping the assemblages. Nevertheless, the amount of variation unexplained by the measured abiotic variables was relatively high (73%), suggesting the effect of additional regulatory factors. Many fish species use the shallow waters of the bay in transitory or permanent ways, and knowledge about their relationship with the environment is necessary for the success of conservation strategies for this ecosystem.

Diel and seasonal variability in the fish community structure of a mud-bottom estuarine habitat in the Gulf of Mexico

We hypothesized that temporal variation in fish species composition and community structure in a low complexity habitat in the Pueblo Viejo Lagoon, Mexico, is influenced by diel light/dark cycles and tidal stage, and by seasonal changes in salinity and temperature. We collected a total of 17,661 individuals during 2-h interval sampling over six bi-monthly 24-h sampling cycles representing 53 species, of which 11 (∼20%) were previously unknown in the system. Diel variation indicated that significantly higher numbers of individuals and species were caught at night, whereas diversity and evenness were higher during the day. Species richness was significantly higher in July and January, whereas diversity and evenness peaked around May; both were correlated with temperature. Diel variation in species composition was influenced primarily by the light/dark cycle. Cluster analyses of each diel cycle separated fish assemblages from midday samples from those of nocturnal samples, separated by an extended wide transition period as fish moved at dawn and during the late afternoon/dusk. Significant shifts (as determined by MANOVA) in assemblage structure occurred between months. Canonical correspondence analysis showed that temperature and day/night effects were the most important environmental variables structuring the fish community. This constrained ordination also defined species with specific habitat preferences as follows: (i) diurnal, warm temperature species (mainly planktivores) (Brevoortia gunteri, Cetengraulis edentulus, Diapterus auratus, and Membras martinica); (ii) nocturnal, warm temperature species (mainly predators) (Citharichthys spilopterus, Cathorops melanopus, and Bairdiella spp.); and (iii) low temperature, diurnal species (Brevoortia patronus and Mugil curema) or those with twilight and nocturnal distributions (Anchoa mitchilli, the most numerically abundant species). Our results indicate that diel and seasonal changes in fish community structure were mainly related to day/night cycles and temperature regimes.

Trophic resource partitioning among five flatfish species (Actinopterygii, Pleuronectiformes) in a tropical bay in south‐eastern Brazil

Five species of flatfishes in a tropical bay in south‐eastern Brazil were studied to test the hypothesis that resource partitioning along the spatial and size dimensions has been used as a mechanism to enable coexistence. Three zones in the study area were defined according to environmental characteristics (inner, middle and outer). Sampling was conducted by otter trawl tows during daylight hours, between October 1998 and September 1999. Achiridae species (Achirus lineatus and Trinectes paulistanus) showed narrow niche width, indicating a specialized feeding strategy, preying on Polychaeta, and occurring mainly in the inner bay zone. Paralichthyidae (Citharichthys spilopterus and Etropus crossotus) and the Cynoglossidae (Symphurus tessellatus) showed broad niche width and a generalized feeding strategy preying on a large number of Crustacea. Symphurus tessellatus did not change diet with size‐dimension feeding on Amphipoda and Polychaeta, whereas C. spilopterus and E. crossotus shifted diet with growth. Citharichthys spilopterus fed mainly on Mysida and secondarily on shrimps, with juvenile preying on large amounts of Calanoida, whereas adults consumed large amounts of fishes. Isaeidae amphipods were a significant prey for both small and large E. crossotus, whereas Polychaeta Errantia were used mainly by large fishes. Etropus crossotus and S. tessellatus share similar feeding resources in outer bay zone preying on Isaeidae and Polychaeta Errantia. Differences in the Pleuronectiformes diet composition along with spatial and size changes in the use of the available resources contributed to allow the organisms’ coexistence in Sepetiba Bay. The high item diversity used by flatfishes indicates that the system plays an important role as a feeding ground, and that interspecific competition for food was unlikely.

Ecological and biological strategies of Etropus crossotus and Citharichthys spilopterus (Pleuronectiformes:Paralichthyidae) related to the estuarine plume, Southern Gulf of Mexico

Differences in the biological and ecological strategies of two tropical flatfishes, Etropus crossotus (fringed flounder) and Citharichthys spilopterus (bay whiff) are discussed. The comparative analysis was based on the seasonal distribution of relative abundance of the two species and flatfish movements utilizing estuarine plume influenced areas as part of their life cycles. Growth parameters of the von Bertalanffy equation and recruitment were estimated (FISAT software) to compare life cycle patterns. The recruitment patterns illustrate the key difference between “estuarine-dependent” and “estuarine-related” nekton strategies. Both species have a short life cycle with a continuous recruitment activity. E. crossotus is an estuarine-related species, with two recruitment pulses ( winter frontal season), in the estuarine plume on the shelf. C. spilopterus is an estuarine-dependent species, with a main recruitment pulse during the rainy season in the estuarine plume, and a residual secondary pulse inside the adjacent estuarine system (Terminos Lagoon). The results show that the ecological success of these tropical coastal marine flatfish, with similar biological patterns, is based upon the sequential use (in time and space) of estuarine plume influenced habitats, suggesting that fish migration to shallow waters is related to food availability changes as a strategy towards optimum recruitment.

Reproductive and population dynamics of the Bay whiff Citharichthys spilopterus Günther, 1862 (Pleuronectiformes: Paralichthyidae) in the Mamanguá Inlet, Rio de Janeiro, Brazil

Bay whiffs, Citharichthys spilopterus, were sampled in Mamanguá Inlet between March 1990 and March 1992 for evaluation of its reproductive dynamic. Bay whiffs presented a crescent gradient of abundance from the deepest to the shallowest stations. The mean total length by oceanographic station showed a clear tendency of a relationship between bigger sizes and higher depths. Males predominated along the studied period and on the smallest length groups. Higher values of alometric condition factor, gonadosomatic relationship and spawning stage of maturity indicated a higher degree of development of the gonads on March and November. Histological analysis showed spawning females in March and May 1990 in the stations closer to the mouth of the Inlet, and spawned females with old post-ovulatory follicles and high frequency of atresia at shallow stations, suggesting a migration to shallow and protected areas after spawning. Length of first gonadal maturation was 117 mm TL. We could conclude that C. spilopterus completes its life cycle within the Mamanguá Inlet, spawning during autumn (March to May) and possibly November.

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

O objetivo deste estudo foi determinar as mudanças espaciais e ontogenéticas na dieta dos linguados Citharichthys spilopterus Günther, 1862 e Symphurus tessellatus (Quoy &amp; Gaimard, 1824) na Baía de Sepetiba. A área de estudos foi dividida em três zonas (interna, central e externa), onde foram realizados arrastos de fundo diurnos no período entre outubro/1998 a setembro/1999. C. spilopterus apresentou os maiores Índices de Importância Relativa (IIR) para Mysidacea (0.3359) e Amphipoda (0.0805), enquanto S. tessellatus apresentou maiores IIR para Amphipoda (0.7515) e Polychaeta (0.2586). A elevada porcentagem (67,61%) de estômagos vazios em S. tessellatus sugere atividade alimentar noturna. Os espécimes de menor tamanho (CT &lt; 115 mm) de C. spilopterus alimentaram-se de Mysi-dacea na três zonas e os maiores (CT &gt; 115 mm) de Polychaeta na zona interna, Gobiidae na central e Decapoda na externa. Os menores espécimes (CT &lt; 155 mm) de S. tessellatus alimentaram-se principalmente de Amphipoda e os maiores (CT &gt; 155 mm) de Polychaeta na zona interna, e de Amphipoda e Polychaeta na zona externa. Citharichthys spilopterus apresentou maior tamanho de boca e olho, e se alimentou de organismos associados à coluna da água próxima, tendendo a uma dieta mais especialista quando comparado com S. tessellatus que se alimentou de organismos sobre fundo. Apesar das duas espécies terem se alimentado basicamente de Crustacea, apresentaram baixa sobreposição alimentar com 0,1972, provavelmente podendo ser esta a estratégia de separação trófica desenvolvida para permitir a coexistência destas duas espécies relacionadas na Baía.

Composição das populações de linguados (Osteichthyes, Pleuronectiformes) da Baía de Sepetiba, Rio de Janeiro, Brasil

Bi-monthly otter trawl sampling programme using a stratified random design was carried out at Sepetiba Bay (22o54'-23o04'S; 43o34'-44o10'W), from August 1994 to July 1996, aiming to assess the flatfish species composition and their relative abundance. Fourteen species in eight genera, four families and one suborder were identified. Paralichthyidae is the most diverse and abundant family, contributing to 70% of total number of individuals and to 58,8% of total biomass, being comprised of nine species: Etropus crossotus (Jordan & Gilbert, 1882); E. longimanus (Norman, 1933); Citharichthys spilopterus (Gunther, 1862); C. arenaceus (Evermann & Marsh, 1902); C. macrops (Dresel, 1889); Paralichthys orbignyanus (Valenciennes, 1847); P. brasiliensis (Ranzani, 1840); P. patagonicus (Jordan, 1889) e Syacium papillosum (Linnaeus, 1758). Etropus crossotus was the most abundant species amounting 52,5% of the total number and 31,3% of the biomass of Pleuronectiformes, being widespread all over the study area. Additional comments on the species occurrence and their distribution over the Western Atlantic are given and compared to their relative abundance in the Sepetiba Bay.

Feeding biology of the flatfish Citharichthys spilopterus (Bothidae) in a tropical estuary of Mexico

The flatfish Citharichthys spilopterus Günther 1862 is the most common bothid in the coastal lagoons of the Gulf of Mexico. The objective of the present study was to describe the trophic biology of this species in the tropical coastal lagoon of Tampamachoco, Mexico. For the diet analysis, we used multivariate discriminant analysis and trophic niche breadth. The morphological analysis showed that the features of the bucco-pharyngeal cavity, the large stomach and the short intestine of this flatfish relate to a carnivorous habit. The overall diet showed that this species is a third-order consumer, feeding mainly on fish (52%, mainly gobies) and crustaceans (36%, mostly decapods). Diet and trophic niche breadth showed no significant differences between sexes (P > 0.1). By contrast, there were significant ontogenetic differences in the diet and trophic niche breadth, where larger C. spilopterus were almost entirely piscivorous and showed the narrowest trophic niche. As the flatfish grew in size there was a trend toward the consumption of larger prey. The importance of copepods and peracarids correlated inversely with flatfish size (P < 0.001), but fish prey correlated directly to flatfish size (P < 0.001). Likewise, there was an inverse significant correlation between niche trophic breadth and flatfish size (P < 0.005). There were also significant seasonal differences in the diet (P < 0.02), related to the availability and vulnerability of prey in the lagoon during the dry and rainy seasons. However, the trophic niche showed no significant differences between seasons. Finally, we discuss the advantages of discriminant analysis applied to evaluate differences among diets of fish groups when compared with other bivariate and multivariate techniques.

Habitat Utilization by Small Flatfishes in a North Carolina Estuary

Distribution and abundance of flatfish species (<150 mm standard length) were related to habitat characteristics in the Newport River and Back Sound estuaries in North Carolina. Salinity, turbidity, depth, distance from marsh edge, benthic composition, and grain size were used to describe the different shallow water habitats from April through October 1994. One Scophthalmidae, seven Paralichthyidae, one Achiridae, and one Cynoglossidae species were collected during the study including juvenileParalichthys albigutta (gulf flounder),P. dentatus (summer flounder), andP. lethostigma (southern flounder) along with multiple age classes ofCitharichthys spilopterus (bay whiff),Etropus crossotus (fringed flounder),Symphurus plagiusa (blackcheek tonguefish), andTrinetes maculatus (hogchoker). Incidental catches ofAncylopsetta quadrocellata (ocellated flounder),C. macrops (spotted whiff), andScopthalmus aquosus (windowpane) were also made. Flatfish distributions among habitats varied by species, size within species, and season. Regardless of season, the highest densities of flatfishes were found in the upper estuary. All habitats were used by one or more species and most species occurred at several habitats. Some species were significantly more abundant at specific habitat types. Ontogenetic shifts in habitat utilization were found for several species. High densities of smallP. lethostigma, C. spilopterus, S. plagiusa, andT. maculatus occurred in the upper estuary on muddy substrates. LargeP. dentatus, C. spilopterus, S. plagiusa, andT. maculatus utilized sand flats and channels in the lower estuary.