Leave forever or return home? The case of the whitemouth croaker Micropogonias furnieri in coastal systems of southeastern Brazil indicated by otolith microchemistry.

Movements of coastal fish species between estuarine systems (rearing grounds) and adjacent platforms (spawning grounds) are complex and can be influenced by multiple biotic and abiotic factors associated with the life cycle of each species. Understanding fish movement patterns between these habitats is crucial for sustainable management of these resources. We aimed to identify movement patterns of the whitemouth croaker Micropogonias furnieri, an important fishery resource along the southeastern Brazilian coast, through characterization of elemental concentration profiles in otoliths. Signal intensity ratios of Sr86:Ca43 and Ba138:Ca43, measured by a Laser ablation inductively coupled to a plasma mass spectrometry (LA-ICPMS), were analysed. Juveniles and adults fish from three semi-enclosed systems (two bays and one coastal lagoon) and adults from nine adjacent coastal areas were examined. Three main behavioural patterns were identified: 1) Marine Migrant, with a unique and definitive movement from the estuarine area towards the adjacent platform when adult; 2) Estuarine Visitor, with movements from the estuarine area towards the adjacent platform when adult but also performing excursions back to the estuarine areas and back again to the adjacent platform; and 3) Nearshore Resident, with occurrence in the adjacent coastal areas that are influenced by estuarine systems. Estuarine areas with large sea connections (e.g., bays) favour more frequent fish entrances and exits compared with coastal lagoons that have a narrow sea connection. The high eurioic condition and capacity related to adapting to different environmental conditions were detected in this study for M. furnieri, a likely strategy to maintain variation in life histories and successfully adapt to coastal marine systems.

Age and growth of the white croaker Micropogonias furnieri (Perciformes: Sciaenidae) in a coastal area of Southeastern Brazilian Bight

Studies on age and growth of fish populations have direct application in fisheries and contribute for policies of conservation. Our aim was update information on the Micropogonias furnieri growth parameters based on sagittae otoliths annulis readings, and we expected that the studied population from Southeast Brazil can reach more longevity than the reported in the available literature. We examined 286 individuals between August-2010 and July-2011 from Ubatuba Bay, SP. The Total Length ranged 200-480 mm. The determined growth parameters were: Males, L∞ =523.4mm, k = 0.05×year-1, t0 = -8.78 year; Females L∞ = 573.5mm, k = 0.06 × year-1, t0 = -7.49 year. The MI and % of edge type evidenced the formation of one ring per year during autumn/winter, coinciding with low temperature and low growth rate. These results differed from those reported for the Vazzoler’s Population I (summer), and we detected higher longevity (45-48 years) as compared with the recorded in the available information.(AU)

Estudos de idade e crescimento de peixes têm aplicação direta na biologia pesqueira e contribuem para medidas de conservação. Nosso objetivo foi atualizar informações sobre parâmetros de crescimento de Micropogonias furnieri utilizando leitura de anéis etários em otólitos sagittae, esperando que a população do Sudeste do Brasil alcance maior longevidade do que o reportado na literatura. Examinamos 286 indivíduos, capturados entre agosto de 2010 e julho de 2011, na Baía de Ubatuba, SP. O comprimento total variou de 200-480 mm. Foram determinados os parâmetros de crescimento: Machos, L∞ = 523,4 mm, k = 0,05 ano-1, t0 = -8,78 ano; Fêmeas, L∞ = 573,5 mm, k = 0,06 ano-1, t0 = -7,49 ano. O IM e a porcentagem do tipo de borda evidenciaram o padrão de formação anual de anéis no outono/inverno, coincidindo com mais baixas temperaturas e crescimento lento. Estes resultados diferem dos reportados para População I de Vazzoler (verão), e nós detectamos longevidade bem superior (45-48 anos) à descrita anteriormente.(AU)

The Farther the Better: Effects of Multiple Environmental Variables on Reef Fish Assemblages along a Distance Gradient from River Influences.

The conservation and management of site-attached assemblages of coastal reefs are particularly challenging because of the tremendous environmental variation that exists at small spatial scales. In this sense, understanding the primary sources of variation in spatial patterns of the biota is fundamental for designing effective conservation policies. We investigated spatial variation in fish assemblages around the windward and leeward sides of coastal islands situated across a gradient of riverine influence (13 km in length). Specifically, relationships between rocky reef fish assemblages and benthic, topographic and physical predictors were assessed. We hypothesized that river induced disturbances may overcome local habitat features in modeling spatial patterns of fish distribution. Fish assemblages varied primarily due to the strong directional gradient of riverine influence (22.6% of the estimated components of variation), followed by topographic complexity (15%), wave exposure (9.9%), and benthic cover (8%). The trophic structure of fish assemblages changed from having a high abundance of invertebrate feeders in macroalgae-dominated reefs close to river mouths to a high proportion of herbivores, planktivores and invertebrate feeder species in reefs with large boulders covered by epilithic algal matrices, as the distance from rivers increased. This gradient led to an increase of 4.5-fold in fish richness and fish trophic group diversity, 11-fold in fish biomass and 10-fold in fish abundance. Our results have implications for the conservation and monitoring of assemblages patchily distributed at small spatial scales. The major role of distance from river influences on fish assemblages rather than benthic cover and topographic complexity suggest that managing land-based activities should be a conservation priority toward reef restoration.

Histochemical and immunohistochemical study on endocrine cells (5HT, GAS, and SST) of the gastrointestinal tract of a teleost, the characin Astyanax bimaculatus.

Endocrine cells secrete hormones through the mucosa of the gastrointestinal tract (GIT) and act on the overall regulation of digestive processes such as nutrient absorption, gut motility and intestinal blood flow. This study aimed to determine regional distribution and frequency of endocrine cells secretory of serotonin (5-HT), somatostatin (SST) and gastrin (GAS) in the GIT of a small-bodied widespread characin Astyanax bimaculatus using histological, histochemical and immunohistochemical techniques. Fragments of the stomach and gut fixed for 8h in Bouin liquid were subjected to histological processing and immunohistochemical routine. For the histological analyses, the technique of staining with hematoxylin and eosin (HE) was used, whereas for the histochemical analyses Gomori's trichrome, periodic acid+Schiff (PAS) and Alcian blue pH 2.5 (AB) were used to further immunohistochemical processing. The stomach has a mucosa lined with a simple columnar epithelium with mucus-secreting cells; the glandular region (proximal and distal portions) has folds and pits, whereas the non-glandular region has pits only. The intestinal epithelium is simple with plain cylindrical grooved and goblet cells. The anterior region has thin folds with few goblet cells, and the posterior region with thick folds and many goblet cells. The regional distribution and frequency of endocrine cells varied across regions of the GIT with the stomach showing the highest amount of immunoreactive (IR) cells. Only the 5-HT was found in the stomach (epithelia and glands) and gut regions, with comparatively higher frequency in the stomach. SST-IR cells were found in the stomach (epithelia and gastric glands) with higher frequency in the glandular region, whereas GAS-IR were found in the gastric glands only. The stomach was the only organ to have all the three types of endocrine cells, indicating that this organ is the main site of digestion of food in this species.

Immunohistochemical study of the digestive tract of Oligosarcus hepsetus.

AIM: To describe the histology of the digestive tract and to investigate the occurrence of endocrine cells in Oligosarcus hepsetus (O. hepsetus). METHODS: The digestive tract (DT) of O. hepsetus was divided into esophagus, two stomach regions (glandular and non-glandular) and two intestinal regions (anterior and posterior). These specimens were processed by routine histological techniques and stained with hematoxylin-eosin, Gomori's trichrome, periodic acid Schiff (PAS) and Alcian blue (AB). An immunohistochemical method using avidin-biotin-peroxidase was employed. RESULTS: The esophagus is lined with a non-keratinized stratified squamous epithelium that is reactive to PAS and AB. The stomach has a mucosa lined with a simple columnar epithelium with mucus-secreting cells that are reactive only to PAS. The intestine has a simple columnar epithelium with a brush border and goblet cells that are reactive to PAS and AB. Somatostatin, serotonin and cholecystokinin immunoreactive cells were identified throughout the DT. CONCLUSION: This study revealed adaptations for the species' diet and showed that the distribution and relative frequency of immunoreactive cells are similar to those of other fish.

Length correction for early-juvenile Brazilian herring Sardinella janeiro (Eigenmann, 1894) after preservation in formalin, ethanol and freezing

This work aims to quantify the variation in total length and body mass for the early-juvenile Brazilian herring Sardinella janeiro and to determine total length and body mass correction equation to allow fresh measures to be calculated from preserved ones. Fishes were randomly assigned to one of five preservation methods (freezing at - 20º C, 2.5 percent and 5 percent formalin, 70 percent and 95 percent ethanol), and measured for total length (TL) and body mass (W) before preservation, and on days 5, 15, 30, and 60 after storage. Significant reductions in total length and body mass occurred during the first 5 days after preservation and continued to contract significantly at a lesser rate through 30 days in most methods. Exceptions were shown for body mass in freezing and 5 percent formalin, where the greatest losses occurred after 30 days of preservation. The degree of shrinkage for total length and body mass was very much dependent on fish size, with smaller specimens shrinking more than larger ones. The fresh total length and body mass can be back-calculated using equations that describe the relationship between fresh and preserved individuals after 60 days storage for all methods except for body mass in freezing.(AU)

Este trabalho objetivou quantificar a variação do comprimento total e massa corporal para pós-larvas de Sardinella janeiro e determinar as equações de correção para o cálculo do comprimento total e da massa corporal a partir de espécimes preservados. Os peixes foram submetidos aleatoriamente a cinco métodos de preservação (congelamento - 20º C, formalina 2,5 por cento e 5 por cento, álcool 70 por cento e 95 por cento), e medidos o comprimento total (CT) e pesado a massa corporal (P) antes da preservação, e 5, 15, 30 e 60 dias após a preservação. Foram observadas perdas significantes no comprimento total e na massa corporal durante os cinco primeiro dias após a preservação, prosseguindo em menor intensidade até o 30º dia na maioria dos métodos. Exceções foram observadas para a massa corporal em congelamento e formalina 5 por cento, com perdas ocorrendo mesmo depois de 30 dias de preservação. O grau de perdas para comprimento total e massa corporal foi significativamente dependente do tamanho dos peixes, com os menores indivíduos sofrendo as maiores perdas. O comprimento total e massa corporal de indivíduos frescos podem ser retro-calculados usando equações que descrevem a relação entre indivíduos frescos e após 60 dias de preservação para a maioria dos métodos, exceto para a massa corporal em congelamento.(AU)

Habitat selection by anchovies (Clupeiformes: Engraulidae) in a tropical bay at Southeastern Brazil

Distribution of anchovies (Clupeiformes, Engraulidae) was described in the Sepetiba Bay, a coastal area of Southeastern Brazil, to assess eventual mechanisms of habitat selection. Two fish sampling programmes were accomplished; one using beach seine (1998/2000) to catch juveniles in sandy beaches, and the other, using seines (1999/2000) to catch adults in deeper bay areas. Six species representing 4 genera were recorded: Anchoa tricolor, Anchoa januaria, Anchoa lyolepis, Cetengraulis edentulus, Engraulis anchoita and Lycengraulis grossidens. Anchoa tricolor and A. januaria were the most abundant species, with the former peaking in the outer bay, while the latter peaking in the inner bay. Adults A. tricolor are target of heavy commercial fisheries in the bay during Spring-Summer, while E. anchoita, an abundant species in the continental shelf, was occasionally caught in large numbers during the Autumn. The habitat selection, by using two different bay areas, was developed by the two most abundant species, a probable mechanism to enable their coexistence.

A distribuição de manjubas (Clupeiformes, Engraulidae) foi descrita na Baía de Sepetiba, uma área costeira do Sudeste do Brasil, para determinar eventuais mecanismos de seleção de habitat. Dois programas de amostragem foram realizados; um usando arrasto de praia (1998/2000) para captura de juvenis, e outro, usando arrasto de fundo (1999/2000) para captura de adultos. Seis espécies representadas por quatro gêneros foram capturadas: Anchoa tricolor, Anchoa januaria, Anchoa lyolepis, Cetengraulis edentulus, Engraulis anchoita e Lycengraulis grossidens. Anchoa tricolor e A. januaria foram as espécies mais abundantes, com a primeira ocorrendo principalmente na zona externa da baía, enquanto a segunda com maior abundância na zona interna. Adultos A. tricolor são alvo de intensas pescarias comercial na baía durante a Primavera-Verão, enquanto E. anchoita, uma abundante espécie na plataforma continental, foi ocasionalmente capturada em grande numero durante o Outono. A seleção de hábitat, através do uso de diferentes áreas da baía, foi desenvolvida pelas duas espécies mais abundantes, um provável mecanismo para permitir a coexistência.

Induced alkoxyresorufin-O-dealkylases in tilapias (Oreochromis niloticus) from Guandu river, Rio de Janeiro, Brazil.

The activity of fish monooxygenases has been extensively used as a monitoring tool to detect contamination of water bodies by cytochrome P450-inducing agents. In this study we evaluated the activities of ethoxy- (EROD), methoxy- (MROD) and pentoxy- (PROD) resorufin-O-dealkylases in the liver of Nile tilapias (Oreochromis niloticus) collected at the Guandu river, at a reference clean site (Lake 1) and at two other sampling sites (Lakes 2 and 3) in Rio de Janeiro state, Brazil. Alkoxyresorufin-O-dealkylases were measured fluorimetrically in the hepatic S9 fraction. EROD (17.7-fold), MROD (14.2-fold) as well as PROD activities were considerably higher in tilapias from Guandu river. A moderate increase of EROD (5.0-fold) and MROD (5.4-fold) was also found in tilapias from Lake 3. These findings suggest that Guandu river watershed, the main source of urban drinking water supply in Rio de Janeiro, is polluted with CYP1A-inducing xenobiotics. Furthermore, we also found a good linear relationship between EROD and MROD, a finding that agrees with the hypothesis that the two reactions are catalysed by the same CYP1A isoform in O. niloticus.