Influence of sex and age on the feeding habits of the common soleSolea solea (original) (raw)
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The soles Solea solea and Solea senegalensis are marine flatfish that use coastal and estuarine nursery grounds, which generally present high food availability, refuge from predators and favourable conditions for rapid growth. Two important nursery grounds for these species juveniles have been identified in the Tagus estuary, one in the upper part of the estuary (nursery A) and another in the south bank (nursery B). While S. solea is only present at the uppermost nursery area, S. senegalensis is present at both nurseries. Although they are among the most important predators in these nursery grounds, there are no estimates on their food consumption or on the carrying capacity of the system for soles. The Elliott and Persson [1978. The estimation of daily rates of food consumption for fish. Journal of Animal Ecology 47, 977e993] model was used to estimate food consumption of both species juveniles in both nursery areas, taking into account gastric evacuation rates (previously determined) and 24 h sampling surveys, based on beam-trawl catches carried out every 3 h, in the summer of 1995. Monthly beam trawls were performed to determine sole densities over the summer. Density estimates and daily food consumption values were used to calculate total consumption over the summer period. Sediment samples were taken for the estimation of prey densities and total biomass in the nursery areas. Daily food consumption was lower for S. solea (0.030 g wet weight d À1 ) than for S. senegalensis (0.075 g wet weight d À1 ). It was concluded that thermal stress may be an important factor hindering S. solea's food consumption in the warmer months. Total consumption of S. solea over the summer (90 days) was estimated to be 97 kg (wet weight). Solea senegalensis total consumption in nursery A was estimated to be 103 kg, while in nursery B it was 528 kg. Total prey biomass estimated for nursery A was 300 tonnes, while for nursery B it was 58 tonnes. This suggests that food is not a limiting factor for sole in the Tagus estuary. However it was concluded that more in-depth studies into the food consumption of other species and prey availability are needed in order to determine the carrying capacity of this system for sole juveniles.
ABSTABCT T he food and feeding habits of the Egyptian Sole, Solea aegyptiaca (Chabanauad, 1972) were studied in Port Said area, Mediterranean Sea during the period from October 2004 to September 2005. The annual composition of the diet, the intensity of feeding, seasonal variation of diet composition and variation of diet with length, showed a low-intensity of feeding activity of S. aegyptiaca, and indicated that they feed on a wide variety of prey types (polychaetes, mollusks, amphipods, sediments and small quantities of crustacean fragments, Ascidia, fish parts, sea grasses, brittlestars, unknown medusae and algae), with a limited variation in diet among seasons. The prey types and size differed from juvenile to adults, juvenile ingested only 5 small prey items; while adult had eaten about 11 of large sized prey items. The diet composition of Egyptian sole is indicative of a generalist feeding strategy.
Seasonal Trophic Ecology and Diet Shift in the Common Sole Solea solea in the Central Adriatic Sea
Animals
The common sole, Solea solea, is one the most important commercial species in Europe and, within the Mediterranean, the Adriatic basin is the most crucial area for its production. Although the species is overexploited in the basin, data on its trophic ecology are fragmentary, even though this is one of the most important features within the Ecosystem Approach to Fishery. Here, we analysed temporal variations in the feeding ecology of the species by using an integrated approach of stomach contents and stable isotope analyses coupled with the analysis of some condition indices such as the gonadosomatic and the hepatosomatic indices. Changes in diet and trophic level across the years in adult females were clearly linked to the different energetic requirements facing reproduction. Temporal changes throughout the year were mainly related to changes in food availability. This study confirms the opportunistic behaviour of this benthophagous species and its role as a mesopredator, opening n...
Environmental Biology of Fishes, 1999
To evaluate the impact of metamorphosis on the vertical distribution and feeding activity of sole, Solea solea, larvae passing from offshore spawning grounds to the Bay of Vilaine, sampling series at fixed stations were carried out in April 1991 and April 1993 at depths from 50 to 30 m. Comparisons between plankton and bottom samplin series indicated differences in vertical distribution of larvae in pre-metamorphic and metamorphic steps. Metamorphosing larvae displayed a tendency to concentrate in the lower part of the water column, mainly during the day. Gut contents, analysed for prey identification, fullness index and carbon content, indicated that metamorphosing larvae fed mostly on plankton. Variations in fullness index were observed not only during the day, but also depended on tide and wind-induced mixing conditions. Larvae sampled in mixed spring-tide waters had highly variable carbon estimates, resulting in unclear diel activity. More larvae fed actively at neap-tide, which allowed the observation of a diurnal feeding activity through hourly changes in carbon estimates. It is concluded that immigrating sole were not yet able to settle but prepared themselves for demersal life (i) without undergoing starvation and (ii) by modifying the patterns of vertical distributions. The presence of a larval swimbladder suggests they can adjust their vertical movements, depending on tidal cycles, which could in turn favour coastal accumulation of metamorphosing larvae and pulses of new settlers entering the nursery grounds.
Feeding ecology, age, growth and sexual cycle of the Portuguese sole, Synaptura lusitanica
Journal of the …, 2003
Portuguese sole, Synaptura lusitanica, were collected from the Portuguese coast, between April 2001 and March 2002, to examine feeding habits, age and growth, and sexual cycle. Synaptura lusitanica fed on few prey items, its diet mainly composed of polychaeta, bivalvia and cephalochordata. Signi¢cant di¡erences were found between the proportion of prey items according to season, length class of ¢sh and coastal area. The main di¡erences related to ¢sh size were the higher ingestion of bivalvia by larger ¢sh, in the west coast area, and the increase in the important cephalochordata for ¢sh larger than 300 mm total length, in the south coastal areas. Polychaeta presented a lower importance in the spring^summer period while bivalvia increased its values in the autumn^winter period. Cephalochordata were more important in the autumn^winter period, but only for ¢sh larger than 300 mm total length and in the south coastal areas. Vacuity was extremely high (mean value of 52%). Ages of S. lusitanica were determined from sagittae otoliths. The length of ¢sh analysed varied from 157 mm to 480 mm, and the oldest ¢sh was age 8. The von Bertalan¡y growth equation parameters di¡ered little between sexes, being the asymptotic length obtained for females higher compared to males. The highest values of the gonadosomatic index were obtained in summer, which was the period when the highest percentage of individuals in the spawning stage were recorded. Therefore, the spawning season seems to be from mid-spring (May) until the end of summer (September).
ABSTRACf. -The stomach contents of Diplodus vulgaris and Spondyliosoma camharus were analysed using three simple methods (numeric, gravimetric and frequency of occurrence) and a composite index (I.R.I -Index of Relative Importance). To compare the species, the Schoener index was used. The diet of D. vulgaris consisted mainly of ophiuroids, polychaetes, amphipods and echinoids, while polychaetes, amphipods and hydrozoans dominated in the case of S. cantharus. There were some size-related differences in S. cantharus feeding. Diet overlap was relatively slight, with significant differences in feeding between the two species, notably in terms of greater consumption of echinoderms by D. vulgaris and hydrozoans by S. cantharus. As is the case for the majority of sea breams, D. vulgaris and S. cantharus are characterised by a diverse diet in terms of prey reflecting available prey items in their environment.
Journal of Sea Research, 2007
This study describes the spatial distribution of young-of-the-year common sole based on beam trawl surveys conducted in late summer in the coastal and estuarine parts of the Bay of Biscay (France). Previous studies showed that habitat suitability for juvenile common sole varies according to physical factors and notably bathymetry and sediment structure. Nevertheless, the use of these descriptors alone to model habitat suitability led to considerable unexplained variability in juvenile common sole distribution. Hence, the epibenthic macro-and megafauna collected during beam trawl surveys was taken into account to improve models of habitat suitability for these juvenile flatfish. Ecotrophic guilds based on life traits (behaviour, mobility and feeding) were used to develop generic indicators of trawled benthic fauna. These synthetic descriptors were used in generalized linear models of habitat suitability in order to characterize the distribution of juvenile common sole. This approach significantly improved the description based on physical descriptors and allowed demonstrating that young common sole distribution is related to the density of trawled deposit and suspension feeders and also of carnivorous organisms. These models provide a reliable method to develop indicators of nursery habitat suitability from trawl survey data with the aim of assessing and surveying their quality.
Brazilian Archives of Biology and Technology, 2011
Natural diet of Neohelice granulata in two salt marshes of Lagoa dos Patos, RS were studied. Sampling was performed seasonally and crabs were captured by hand by three persons during one hour, fixed in formaldehyde (4%) during 24 h, transferred to alcohol (70%). Each foregut was weighed and repletion level was determined. Differences between sexes in the frequencies of occurrence of items were tested by χ 2 test. A total of 452 guts were analyzed. Quali-quantitative analyses were calculated following the method of relative frequency occurrence and relative frequency of the points. At both sites, for both sexes and in all seasons, the main food items were sediment, Spartina sp. and plant detritus. The highest values of mean repletion index were estimated for the spring and summer. Analysing both salt marshes, in different seasons significant shifts in the natural diet of Neohelice granulata was not observed throughout the period of study.