Ana Lúcia Vendel

Fish assemblages in a tidal flat

Studies were carried out on fish assemblages in a tidal flat. Samples were obtained monthly at low tide of the half moon in the tidal flat of Paranagua Bay, Brazil, with two seine nets, one with a 1 mm mesh, 30 m in length and 3 m in height and another with a 10 mm mesh, 65 m in length and 2 m in height. A total of 8,890 fish were captured, comprising 24 families and 53 species. The most abundant species were Harengula clupeola and Atherinella brasiliensis, which represented 63.4% of the total, capture. A seasonal tendency was observed in the abundance of fishes, with less fishes being captured during winter and part of spring. The number of species showed a seasonal pattern, with the gradual decrease through winter and a marked increase in summer. The community structure index indicated seasonal changes in the assemblage. The faunistic similarities between months separated the 12 months into four major groups. The seasonal pattern was apparent in the numerically dominant species and the Cluster Analysis revealed five main groups.

Structure and Dynamics of Fish Assemblages in a Tidal Creek Environment

Studies were carried out on structure and dynamics of fish assemblages in the Baguacu tidal creek, Paranagua Bay, Brazil. A total of 30,104 fish were captured, comprising 21 families and 47 species. Both in weight and in number, the species Anchoa parva prevailed. Monthly captures in number and weight were largest in the autumn and part of the winter. No seasonal tendency was observed in the indexes of community structure. The dendrogram produced by the classification of the samples separated the 12 months of collection into three groups, reflecting differences in the qualitative and quantitative occurrences of the most important taxa. Some ecological likeness, not only seasonal patterns of abundance, seemed evident in the seasonality of the groupings of species revealed through the cluster analysis. The principal component analysis reflected mainly the periods of rain and drought

Indicadores reprodutivos das espécies de Citharichthys Bleeker (Teleostei, Pleuronectiformes) na Baía de Guaratuba, Paraná, Brasil

The species of Citharichthys Bleeker, 1862, C. arenaceus Evermann & Marsh, 1900 and C. spilopterus Gunther, 1862, are the most common flatfishes found in Guaratuba Bay, south Brazil. Different size categories of these flatfish occur in the mangrove area throughout the year. The Gonadosomatic Index, the Condition Factor, and the morphological analyses of the gonads from samples obtained between 1994 and 1996 reveals a spawning activity during late Spring and early Summer. This period coincides with the increase in temperature and decrease in salinity. Spawning evidence and the presence of ali size categories throughout the year indicate that Citharichthys spp. are permanent inhabitants of the mangrove in Guaratuba Bay, where they complete their life cycle.

Feeding habits of Stellifer rastrifer (Perciformes, Sciaenidae) at Guaratuba mangrove, Parana, Brazil

Feeding habits of Stellifer rastrifer (Perciformes, Sciaenidae) at Guaratuba mangrove, Parana, Brazil, were studied from February 1996 to February 1997. It was observed that its diet was based on invertebrates, mainly Decapoda non-Brachyura and Polychaeta. In a smaller proportion there were plants, Copepoda, Gammaridea and Mollusca. The level of contribution of each food item changed according to the season and the individual size. Such plasticity in feeding behaviour was similar to that described to some fish populations from other estuaries, and could be an indicator of the high level of instability presented by this kind of ecosystem.

Study on feeding habits in estuarine fish (Teleostei) comparatively between salt marshes and mangroves in southern Brazil (Guaratuba Bay)

Estudou-se a composicao da dieta de peixes em dois tipos de ambiente de areas rasas estuarinas - marisma e manguezal, objetivando avaliar se essas formacoes vegetais desencadeiam na ictiofauna respostas diferentes quanto a alimentacao. As seis especies avaliadas, as mais abundantes nessas areas, mostraram-se predominantemente planctivoras, porem com particularidades quanto ao tipo de vegetacao ocupada. Na marisma, Atherinella brasiliensis (Quoy & Gaimard, 1825) apresentou a dieta com maior numero de itens e menor similaridade em relacao as demais especies. No manguezal tal isolamento coube a Anchoa januaria (Steindachner, 1879), especie com maior participacao de Decapoda Brachyura e Decapoda nao-Brachyura, e unica que nesse ambiente incluiu Gammaridae na dieta. Anchoviella lepidentostole (Fowler, 1911) identificou-se com Anchoa lyolepis (Evermann & Marsh, 1900) na marisma e com Opisthonema oglinum (Le Sueur, 1818) e Harengula clupeola (Cuvier, 1829) no manguezal. Uma situacao comum a marisma e manguezal registrou-se entre O. oglinum e H. clupeola, especies com dietas praticamente restritas a Diatomacea e Copepoda. Evidenciou-se o quanto as especies sao capazes de variar sua dieta com o ambiente, provavelmente em resposta a disponibilidade local. Mais que isso, porem, constatou-se que, seja na marisma, seja no manguezal, mesmo havendo mudanca nos habitos troficos das especies, cada uma delas mantem um padrao de diferencas em relacao as demais que compoem a assembleia, fato que possivelmente assegura a abundância e coexistencia entre elas nas areas estuarinas rasas.

Alimentação de Bairdiella ronchus (Cuvier) (Perciformes, Sciaenidae) na Baía de Guaratuba, Paraná, Brasil

Seasonal variation of food items of Bairdiella ronchus (Cuvier, 1830) classified by size was analysed based on monthly samples between september/1993 and september/1996 at the Guaratuba Bay, Southern Brazil. The stomach contents of a hundred eighty-two fishes were analysed by the Occunence Frequency Method and Point Count for a Lot Method. The individuais were divided in two groups, smaller and longer than 140mm, and a comparative study of digestive tract and branchial are was performed for these groups. For fishes smaller than 140mm the following sequence of items was obtained matching both methods by using the Preponderance indices: decapods (subdivided in Brachyura, Caridea and Penaeidea), polychaets, isopods, fishes, unidentified material, copepods, amphipods, molluscs and plant material. For fishes longer than or equal to 140mm the sequence was decapods, polychaets, fishes, copepods, amphipods, isopods, molluscs and plant material, in this order. These results suggest that Bairdiella ronchus at the Guaratuba Bay is a carnivorous species using mainly decapod crustaceans as food throughout the year.

Environmental and subtidal fish assemblage relationships in two different brazilian coastal estuaries

The general structure and organization of the shallow water (<1.5 m) fish assemblages were studied in two southern Brazilian ecosystems, a bay and a lagoon, under different marine or continental influences. The abiotic factors were measured to define the hydrology of the sites and the biotic descriptors were evaluated to characterize the assemblage structures. Transparency, salinity and organic matter were the abiotic factors which best distinguished the sites. A total richness of 69 species was observed. Ecological guilds, density, diversity and evenness indices values were different in each site. Hydrodynamism and geomorphology determined the structure and the organization of the fish assemblages in these shallow waters. It was observed that variations in the hydrological attributes generated by the marine or continental water movements are able to alter the conditions in the lagoon more quickly and at more regular frequencies than those in the bay.