The feeding habits of the endemic Remo flounder, Oncopterus darwinii (Actinopterygii: Pleuronectidae), in an exposed sandy beach’s surf zone in southern Brazil

ABSTRACT The Remo flounder, Oncopterus darwinii Steindachner, 1874 is a small Pleuronectidae (~ 250 mm TL) distributed in the warm-temperate zone from Santa Catarina (28°S - Brazil) to the Gulf of San Matías (42°S - Argentina). We studied the occurrence and diet of juveniles of this flatfish (85% < 100 mm TL) for one year (August 2009 to July 2010) in a southern Brazilian sandy beach. Individuals were much more common in spring and early summer than in the other seasons. Of the 758 individuals analyzed, only 69 (9.1%) were found with empty stomachs. The Remo flounder fed predominantly on small crustaceans (gammarid amphipods, mysids and the hipiidae Emerita brasiliensis Schmitt, 1935) and no seasonal differences were found in the composition of the diet of this flatfish. However, variations in the Index of Relative Importance (IRI) were found among seasons, which most likely can be explained by a decrease in the availability of favored food items throughout the year. The pattern of distribution of O. darwinii indicates that southern Brazilian sandy beaches are used as nursery ground for this species

The feeding habits of the endemic Remo flounder, Oncopterus darwinii (Actinopterygii: Pleuronectidae), in an exposed sandy beach’s surf zone in southern Brazil

The Remo flounder, Oncopterus darwinii Steindachner, 1874 is a small Pleuronectidae (~ 250 mm TL) distributed in the warm-temperate zone from Santa Catarina (28°S – Brazil) to the Gulf of San Matías (42°S – Argentina). We studied the occurrence and diet of juveniles of this flatfish (85% < 100 mm TL) for one year (August 2009 to July 2010) in a southern Brazilian sandy beach. Individuals were much more common in spring and early summer than in the other seasons. Of the 758 individuals analyzed, only 69 (9.1%) were found with empty stomachs. The Remo flounder fed predominantly on small crustaceans (gammarid amphipods, mysids and the hipiidae Emerita brasiliensis Schmitt, 1935) and no seasonal differences were found in the composition of the diet of this flatfish. However, variations in the Index of Relative Importance (IRI) were found among seasons, which most likely can be explained by a decrease in the availability of favored food items throughout the year. The pattern of distribution of O. darwinii indicates that southern Brazilian sandy beaches are used as nursery ground for this species

Diet and feeding strategy of the dusky grouper Mycteroperca marginata (Actinopterygii: Epinephelidae) in a man-made rocky habitat in southern Brazil

The dusky grouper (Mycteroperca marginata) is a marine species usually associated with rocky bottoms and reefs. The present work investigated the diet and feeding strategy of a dusky grouper population inhabiting a 4.5 km long pair of rocky jetties located in the mouth of Patos Lagoon estuary. No prior research has been conducted in such man-made habitat and the current study provides a basis for comparative studies on the diet of the dusky grouper populations inhabiting natural vs. man-made rocky habitats. Similarly with previous studies on natural substrates, crabs and fishes were the main food categories consumed (%IRI = 85.1 and %IRI = 12.6, respectively), whereas shrimps and mollusks had lower importance in the diet (%IRI = 1.9 and 0.4, respectively). As previously reported for dusky grouper populations inhabiting reefs and rocky bottoms, the present work revealed conspicuous size related dietary shifts. Blue crabs and fishes become increasingly important food items in the diet of larger individuals (> 500 mm, TL). Finally, it was found that the studied dusky population has a generalist feeding strategy with a high between-individual variation in prey consumption. Such strategy remained similar across the size increment of the species. Our findings suggest that man-made rocky substrates provide suitable feeding grounds for the dusky grouper in southern Brazil and could be used as an additional tool in the conservation efforts of this endangered species

The feeding habits of the endemic Remo flounder, Oncopterus darwinii (Actinopterygii: Pleuronectidae), in an exposed sandy beach’s surf zone in southern Brazil

<div><p>ABSTRACT The Remo flounder, Oncopterus darwinii Steindachner, 1874 is a small Pleuronectidae (~ 250 mm TL) distributed in the warm-temperate zone from Santa Catarina (28°S - Brazil) to the Gulf of San Matías (42°S - Argentina). We studied the occurrence and diet of juveniles of this flatfish (85% < 100 mm TL) for one year (August 2009 to July 2010) in a southern Brazilian sandy beach. Individuals were much more common in spring and early summer than in the other seasons. Of the 758 individuals analyzed, only 69 (9.1%) were found with empty stomachs. The Remo flounder fed predominantly on small crustaceans (gammarid amphipods, mysids and the hipiidae Emerita brasiliensis Schmitt, 1935) and no seasonal differences were found in the composition of the diet of this flatfish. However, variations in the Index of Relative Importance (IRI) were found among seasons, which most likely can be explained by a decrease in the availability of favored food items throughout the year. The pattern of distribution of O. darwinii indicates that southern Brazilian sandy beaches are used as nursery ground for this species.</p></div

Age, growth, and reproductive aspects of the dusky grouper Mycteroperca marginata (Actinopterygii: Epinephelidae) in a man-made rocky habitat in southern Brazil

The dusky grouper, Mycteroperca marginata, is an important commercial marine fish that is currently considered an endangered species worldwide and listed as overexploited in Brazil. Although its reproductive biology has been studied elsewhere, no information is available for populations in its southernmost distribution limit on the Brazilian coast. The present work investigates age structure, growth and reproduction of individuals inhabiting a pair of rocky jetties, about 4.5 km long each, located in the mouth of Patos Lagoon in the municipality of Rio Grande, in the southwestern Atlantic Ocean. A total of 130 individuals obtained between February 2007 and May 2009 were analyzed, with total length ranging from 260 to 800 mm. The growth coefficient found in the present study (K: 0.069) was lower than values reported for dusky grouper populations from the Mediterranean Sea (0.087) and southeast Africa (0.09). This difference could be related to higher average water temperatures in these regions compared to the current study site or due to poorer habitat quality in terms of the shelters available for dusky grouper individuals to establish their territories. Microscopic ovarian analyses of individuals during three years of sampling revealed only the occurrence of immature and resting females. The absence of ripe or post-spawning individuals, associated with low GSI values (<0.2) over the studied months, indicates that the dusky grouper did not use this man-made rocky substrate as a spawning site. The current L50 estimate of 451.3 mm indicates that most individuals captured in this area are immature. Such fishing pressure on immature specimens, associated with its slow growth rates and complex reproductive characteristics, threatens sustainability of the current dusky grouper fishery at the study site