FEEDING HABITS OF Paralonchurus brasiliensis (PERCIFORMES: SCIAENIDAE) FROM SOUTH OF BRAZIL / Hábitos Alimentarios de Paralonchurus brasiliensis (Perciformes: Sciaenidae) del sur del Brasil

ABSTRACT Shrimp trawling directly impacts target species and non-target species, altering micro-habitats and marine trophic webs. Thus, the objective of the present research was to analyze the feeding habits of Paralonchurus brasiliensis as a tool to evaluate the impact of trawling on the food chains in marine environments, in the South Atlantic of Brazil. One thousand and nineteen stomachs of P. brasiliensis were dissected after being captured as bycatch of shrimp Xiphopenaeus kroyeri, in Penha, on the north central coast of Santa Catarina, Brazil. The number of stomachs was enough to describe the feeding habits of P. brasiliensis, characterizing it as a carnivorous species and predominantly invertivorous. They also revealed that this species has a diversified and constant diet, with greater consumption of polychaetes, crustaceans, and ofiuroides, among other components of the macrobentos, all closely related to the sediment. It was also found that the target species X. kroyeri is not an important prey in the diet of P. brasiliensis, despite occupying the same habitat. According to the present study, P. brasiliensis can be characterized as a demersal-benthic species, predator, opportunistic and broad trophic spectrum. This work contributes to the understanding of trophic chains of the coastal ecosystems, using the P. brasiliensis as a model.

RESUMEN La pesca de arrastre de camarón afecta directamente a la especie de interes y a otras que no lo son, pero tambien quedan atrapadas, alterando los micro-hábitats y las vías tróficas marinas. Así, el presente estudio tuvo como objetivo analizar los hábitos alimentarios de Paralonchurus brasiliensis, como herramienta para evaluar el impacto de la pesca de arrastre sobre las cadenas alimentarias en ambientes marinos, en el Atlántico sur de Brasil. Se disecaron 1219 estómagos de P. brasiliensis capturados con "bycatch" del camarón Xiphopenaeus kroyeri, en Penha, litoral centro-norte de Santa Catarina, Brasil. El número de estómagos fue suficiente para la descripción de los hábitos alimentarios de P. brasiliensis, caracterizándola como una especie carnívora, predominantemente invertívora. Los resultados revelaron además que esta especie posee una dieta diversificada y constante, con mayor consumo de poliquetas, crustáceos y ofiuroides, entre otros componentes del macrobentos, todos íntimamente relacionados al sedimento. Se constató también que la especie de interes X. kroyeri no es una presa importante en la dieta de P. brasiliensis, a pesar de ocupar el mismo hábitat. De acuerdo con el presente estudio, P. brasiliensis puede ser caracterizada como una especie demersal bentónica, predadora, oportunista y de amplio espectro trófico. Este trabajo contribuye a la comprensión de las cadenas tróficas de los ecosistemas costeros, utilizando el caso de P. brasiliensis como modelo.

The influence of black spot disease on the relative condition factor of Astyanax paranae Eigenmann, 1914 (Characiformes: Characidae) in Brazilian subtropical streams

Environmental disturbances and their consequences require constant studies to understand how communities and their ecological relationships respond to these processes. Through analysis of the host-parasite relationships, it is observed that the effect of these disturbances is variable and can change the physiology or behavior of organisms. Black spot disease, caused by endoparasitic helminths, is a pathology observed in natural environments, however, there is not much information about the consequences of this infestation. We separated the specimens from each stream into parasitized and non-parasitized groups, which were subjected to biometric analysis. The biometrics involved cysts count and weight-length measures, which were used to analyze the average relative condition factor. Additionally, we correlate these measures with the parasitic burden of infected individuals. Finally, the parasitized individuals were submitted to histological sections to recognize the parasite. The results demonstrate a low physiological condition in the parasitized group, when compared with non-parasitized groups from the same stream and from different streams. This suggests that pollution, in addition to effects of infestation worsen the fish condition. Besides, the parasite burden was negatively correlated with the condition factor, weight and length measures. We conclude that the parasite burden negatively affects Astyanax paranae individuals´ physiological condition and that trematodes also occur in polluted environments.

Influence of environmental quality of the tributaries of the Monjolinho River on the relative condition factor (Kn) of the local ichthyofauna / Influência da integridade ambiental dos afluentes do Rio Monjolinho sobre o fator de condição relativo (Kn) da ictiofauna local

The relative condition factors (Kn) of the fishes Astyanax paranae, Phalloceros harpagos and Poecilia reticulata were used as a means of assessing the influence of environmental conditions on the well-being of sub - populations of these species, with the eventual aim of using them as bioindicators of disturbance in tributary streams of the Monjolinho River, in São Carlos - SP. The power-law curve generated by the length-weight relationship indicated a positive allometric growth for the three species studied. Overall, the canonical correspondence analysis (CCA) positively correlated average Kn of A. paranae with well oxygenated and oligotrophic environments, typical of conserved areas or near the natural state. For the average value of Kn obtained for Phalloceros harpagosspecies, there was no significant difference between natural and disturbed areas. However, the CCA positively correlated the mean Kn of the speciesP. reticulata from similar environments with higher trophic level, suggesting that this species is indicative of disturbance.

Os fatores de condição relativo (Kn) de Astyanax paranae, Phalloceros harpagos e Poecilia reticulata foram utilizados como ferramenta para avaliar a influência da qualidade ambiental sobre o bem estar de sub-populações destas espécies, visando utilizá-las como bioindicadoras de distúrbios em córregos afluentes do rio Monjolinho, no município de São Carlos - SP. A curva potencial gerada pela relação peso-comprimento indicou um crescimento do tipo alométrico positivo para as três espécies estudadas. No geral, a análise de correspondência canônica (CCA) correlacionou positivamente o Kn médio da espécie A. paranae com ambientes bem oxigenados e oligotróficos, característicos de áreas preservadas ou próximas do estado natural. Para o valor médio do Kn obtido para a espécie Phalloceros harpagos, não ocorreram diferenças significativas entre áreas naturais e perturbadas. Entretanto, a CCA correlacionou positivamente o Kn médio da espécie Poecilia reticulata a ambientes impactados, com maior grau de trofia, o que sugere que o fator de condição relativo desta espécie pode ser utilizado como indicador de distúrbios, neste caso, ocasionado pela poluição orgânica.

Fish community composition, seasonality and abundance in Fortaleza Lagoon, cidreira

A Planície Costeira do Rio Grande do Sul é formada por uma série de corpos dÆágua, dispostos em seqüência ao longo da costa. A lagoa da Fortaleza pertence ao subsistema lagunar Tramandaí-Sul que é composto por lagoas, dispostas linearmente no sentido norte-sul. O do presente estudo teve como objetivo descrever alguns aspectos relacionados à composição da comunidade de peixes da Lagoa da Fortaleza. As amostragens foram realizadas, mensalmente, no período de novembro de 1998 a outubro de 1999. Os exemplares foram capturados em 4 pontos da lagoa previamente determinados e classificados em 5 ordens, 11 famílias e 22 espécies. As espécies Cyphocharax voga, Hyphessobrycon luetkenii, Oligosarcus jenynsii, Oligosarcus robustus e Loricariichthys anus mostraram-se as mais abundantes. Entre as espécies coletadas apenas duas não caracterizam espécies de água doce: Centropomus sp (marinha) and Lycengraulius grossidens (estuarina). A ictiofauna da lagoa caracterizou-se por uma predominância de espécies constantes.

Diet of the clupeid fish Platanichthys platana (Regan, 1917) in two different Brazilian coastal lagoons

Platanichthys platana is considered a constant species in both Cabiúnas and Imboassica lagoons that are characterised by different marine and freshwater inputs, and anthropogenic influences. The stomach content analysis of P. platana captured between July 1991 and July 1993 revealed filamentous algae, detritus, eggs of benthic invertebrates, larvae of chironomids and bivalves as the main food sources in Imboassica lagoon. Small-sized cladocerans, copepods and shrimp larvae were the prevailing items in Cabiúnas lagoon. Seasonal food variations were noted for the fishes of Imboassica lagoon. Diet differences were highlighted within specimens lesser than 40 mm standard length in Imboassica lagoon, and were related to the increase of marine influence due to artificial sand barrier openings. Dissimilarities among size classes in relation to invertebrate larvae consumption were observed in fishes from Cabiúnas lagoon

Induced reproduction and reproductive characteristics of Rhinelepis aspera Agassiz, 1829 (osteichthyes: Siluriformes, Loricariidae)

Rhinelepis aspera is the largest Loricariidae species found in the São Francisco river basin where it is now rarely caught. Brooders kept in tanks were hypophysed with crude carp pituitary extract (CCPE). Approximately 82 percent of the females responded positive to the treatment. The egg was opaque, demersal, round, yellow and adhesive. Egg stripping was done at 212 hour-degrees (= 8.2 h) after application of the second dose of CCPE (water temperature = 25-26 ºC). Hatching of the larvae occurred at 1022 hour-degrees (= 42.2 h), after fertilization of the eggs (water temperature =24-25 ºC). Fertilization rate of the eggs was 72 percent. Absolute fecundity (AF), initial fertility (IF) and final fertility (FF) in relation to the females' body weight are expressed, respectively, by the equations: AF = - 33993 + 122308 Wt (r² = 0.88), IF = - 14823 + 58619 Wt (r² = 0.71) and FF = - 6553 + 29741 (r² = 0.61).

Rhinelepis aspera é a espécie que atinge maior porte dentre os Locariidae da bacia do rio São Francisco onde é hoje raramente capturada. Reprodutores mantidos em viveiros foram hipofisados com extrato bruto de hipófise de carpa (EBHC). Aproximadamente 82 por cento das fêmeas responderam positivamente ao tratamento. Seus ovos eram opacos, demersais, arredondados, amarelados e adesivos. A extrusão dos ovos foi feita a 212 horas-graus (= 8,2 h) após a aplicação da segunda dose de EBHC (temperatura da água = 25-26 ºC). A eclosão das larvas ocorreu a 1022 horas-graus (= 42,2 h) após a fertilização dos ovos (temperatura da água = 24-25 ºC). A taxa de fertilização dos ovos foi de 72 por cento. Fecundidade absoluta (AF), fertilidade inicial (IF) e fertilidade final (FF) em relação ao peso corporal das fêmeas foram expressa, respectivamente, pelas equações: AF = - 33993 + 122308 Wt (r² = 0,88), IF = - 14823 + 58619 Wt (r² = 0,71) e FF = - 6553 + 29741 (r² = 0.61).