Padrões de crescimento em otólitos de larvas de Pomatoschistus pictus (Pisces, Gobiidae)

Dissertação mest., Biologia Marinha, Universidade do Algarve, 2006

Padrões verticais e inter-anuais nas assembleias de larvas de peixe junto ao substrato rochoso do Parque Marinho da Arrábida

Dissertação de mest., Biologia Marinha, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2009

Feeding ecology and trophic relationships of fish species in the lower Guadiana River Estuary and Castro Marim e Vila Real de Santo Antonio Salt Marsh

In this study we analyze the feeding ecology and trophic relationships of some of the main fish species (Soleidae, Moronidae, Mullidae, Sparidae, Mugilidae, and Batrachoididae) of the lower Estuary of the Guadiana River and the Castro Marim e Vila Real de Santo Antonio Salt Marsh. We examined the stomachs of 1415 fish caught monthly between September 2000 and August 2001. Feeding indices and coefficients were determined and used along with the results of multivariate analysis to develop diagrams of trophic interactions (food webs). Results show that these species are largely opportunistic predators. The most important prey items are amphipods, gobies (Gobiidae), shrimps (Palaemon serratus and Crangon crangon), and polychaete worms. The lower Estuary and associated salt marshes are important nurseries and feeding grounds for the species studied. In this area, it is therefore important to monitor the effects of changes in river runoff, nutrient input, and temperature that result from construction of the Alqueva Dam upstream. (c) 2006 Elsevier Ltd. All rights reserved.

Feeding habits of the deep-snouted pipefish Syngnathus typhle in a temperate coastal lagoon

Feeding habits of Syngnathus typhle were determined based on monthly sampling during experimental fishing in a coastal lagoon (Ria Formosa, South Portugal) from April 2004 to May 2002. The gut contents of 856 individuals were analysed and quantified with numerical and gravimetric methods, as well as with some complementary indices and measures (vacuity, fullness and relative importance). In this study, this species fed mainly on Copepoda, Mysidacea, small caridean grass shrimps (Hippolytidae and Palaemonidae) and small fishes (Gobiidae) and to a lesser degree on other small invertebrates. No significant differences were found between the diets of males and females. However, significant differences in the fullness indexes of both sexes were observed during the reproductive period. Significant differences in the diet among seasons were also verified but no seasonal trends were discovered. Snout length showed a linear increase with growth while mouth area and total length displayed an allometric relation. Mouth shape varied between an ellipse and an almost perfect circle. The increase in mouth area and snout length as S. typhle grows contributed to the observed ontogenic diet shift with specimens smaller than 10 cm feeding almost exclusively on Copepoda, medium sized specimens feeding mainly on Hippolytidae and Mysidacea, while larger specimens preyed on Hippolytidae, Palaemonidae and Gobiidae. Prey size generally increased with size of S. typhle. (c) 2007 Elsevier Ltd. All rights reserved.