Search results for "predation"
showing 10 items of 589 documents
Drilling predation on Gryphus vitreus (Brachiopoda) off the French Mediterranean coasts
2004
Abstract A total of 145 valves of Gryphus vitreus with naticid drillholes have been recorded from samples during 21 cruises in the Northwestern Mediterranean, out of about 30,000 empty valves. Drilling was lower than 1% in all stations, except in one station where it reached up to 25.5%. Selectivity of drillhole site by the naticid Euspirella pulchella seems to apply in G. vitreus as drillholes are mainly concentrated in the relatively meaty distal half of the shell, which is also the thickest part of the valve (about 0.6–2 mm). Attacks occur generally on the ventral valve (86.2%) according to the life position of Gryphus. The predation pressure on G. vitreus by drilling appears exceptional…
Diet and diving behaviour of European Storm Petrels Hydrobates pelagicus in the Mediterranean (ssp. melitensis).
2011
Capsule Unlike Atlantic populations, which feed on krill, Mediterranean populations feed mainly on pelagic fish Gymnammodites cicerellus. Aims To determine the diet and dive depth of the Mediterranean subspecies of European Storm Petrels Hydrobates pelagicus melitensis. Methods Analysis of regurgitates of adults arriving at the colony for chick feeding and by determination of dives depth using the capillary tube method. Results The main prey is Gymnammodites cicerellus, a pelagic fish. Storm Petrels dive for their prey and can reach up to 5 m in depth. They also make short foraging trips just outside the colony where they capture Opossum Shrimps Misydacea. Conclusions European Storm Petrels…
Transmission and Predictors of Burden of Lungworms of the Striped Dolphin (Stenella coeruleoalba) in the Western Mediterranean
2020
Pseudaliid lungworms infect the lungs and sinuses of cetaceans. Information on the life cycle and epidemiology of pseudaliids is very scarce and mostly concerns species that infect coastal or inshore cetaceans. Available evidence indicates that some pseudaliids are vertically transmitted to the host, whereas others are acquired via infected prey. We documented pseudaliid infections in an oceanic cetacean, the striped dolphin (Stenella coeruleoalba) in the western Mediterranean, and investigated the possibilities of vertical vs. horizontal transmission and the potential influence of host body size, sex, and season on infection levels. We found two species of lungworm in 87 dolphins that stra…
Microplastics ingestion by the exotic fish Gambusia holbrooki in two Mediterranean coastal lagoons
2020
Gambusia holbrooki es un pequeño pez Poecílido, de origen norteamericano que fue introducido a principios del siglo XX en humedales de la Península Ibérica para el control biológico de los mosquitos. Actualmente presenta poblaciones en muchos humedales y está considerada como una de las principales especies invasoras en la península. Estos peces se alimentan principalmente de invertebrados, pero son también susceptibles de ingerir y acumular residuos de microplásticos que presentan tamaños similares al tamaño de algunas de sus presas habituales. En el presente estudio analizamos los contenidos del tracto gastrointestinal de ejemplares adultos de esta especie, procedentes de dos lagunas cost…
Macroalgal assemblage type affects predation pressure on sea urchins by altering adhesion strength.
2010
In the Mediterranean, sea breams are the most effective Paracentrotus lividus and Arbacia lixula predators. Generally, seabreams dislodge adult urchins from the rocky substrate, turn them upside down and crush their tests. Sea urchins may respond to fish attacks clinging tenaciously to the substratum. This study is the first attempt to investigate sea urchin adhesion strength in two alternative algal assemblages of the rocky infralittoral and valuated its possible implication for fish predation. We hypothesized that (1) sea urchin adhesion strength is higher in rocky shores dominated by encrusting macro-algae (ECA) than in erected macro algae (EMA); (2) predation rates upon sea urchins are …
Diet of Phycis blennoides (Gadidae) in Relation to Fish Size and Season in the Western Mediterranean (Spain)
2002
. Despite its commercial value, little is known about the feeding ecology of the greater forkbeard, Phycis blennoides (Brunnich 1768). The stomach contents of 2631 greater forkbeard were taken at monthly intervals off the coast of the Gulf of Valencia (western Mediterranean). They were examined in order to assess the diet and to determine the fish size- and season-related dietary variation of the species. Prey items were identified to the lowest taxonomic level possible. The basic food consisted of epibenthic species, mostly Decapoda, Mysidacea and Teleostei. A change in food composition based on fish size was observed and seasonal variation in diet was also recorded. The food overlap analy…
Stable C and N isotope concentration in several tissues of the loggerhead sea turtle Caretta caretta from the western Mediterranean and dietary impli…
2007
CONCENTRACIÓN DE ISÓTOPOS ESTABLES DE C Y N EN VARIOS TEJIDOS DE LA TORTUGA BOBA CARETTA CARETTA DEL MEDITERRÁNEO OCCIDENTAL E IMPLICACIONES SOBRE LA DIETA. – La concentración isotópica de escudos del caparazón, piel, músculo y sangre de tortuga boba (Caretta caretta) fueron analizados para investigar el patrón de variación entre tejidos y para evaluar la posición de esta especie en las redes tróficas de la cuenca Argelina. La piel presentaba valores más altos de δ13C que el músculo o los escudos del caparazón y éstos presentaban valores más altos que la sangre. En cambio, el músculo presentaba valores más altos de δ15N que la piel, ésta valores más altos que la sangre y ésta valores más al…
Notes on the Biology and Ecology of Opeatogenys gracilis (Canestrini 1864) (Pisces: Gobiesocidae) from Coastal Environments in Sicily (Mediterranean)
2001
A particularly large number of specimens of the Mediterranean coastal fish Opeatogenys gracilis (Canestrini 1864) (Pisces: Gobiesocidae) were collected from Posidonia oceanica mats of the “Stagnone di Marsala” sound (western Sicily) and in the Gulf of Carini (northern Sicily). A study was made of biometric and meristic characters and, for the first time for this species, diet composition. The biometric and meristic data did not distinguish between specimens from the two study sites. In accordance with its benthic habit, O. gracilis feeds on small phytal prey living on Posidonia oceanica leaves. The preferential food items throughout the year were Copepoda Harpacticoida.
Diet and feeding habits of nesting and non-nesting ravens (Corvus corax) on a Mediterranean island (Vulcano, Eolian archipelago)
2003
The almost complete absence of information on the trophic ecology of Corvus corax for Mediterranean areas prompted the present research on the small island of Vulcano. Focal observations allowed us to survey the population, which is divided into four territorial pairs and one non-nesting flock (mean n = 23.6 ± 16.3). This flock roosted preferentially near a rubbish dump. Ravens on Vulcano proved to be omnivorous and to feed upon a wide range of food items, with the differences in diet found to be more quantitative than qualitative and related to the season and to the social system. The flock birds consumed more vegetable matter, carrion of domestic animals, other organic matter (eggshells, …
Effects of recreational scuba diving on Mediterranean fishes: evidence of involuntary feeding?
2013
Despite a large body of literature assessing the impacts of recreational scuba diving on marine habitats, little attention has been paid to the potentially harmful effects this has on fishes. The aim of this study was the assessment of the immediate response of different fish species to divers’ activities. A decrease of fishes’ natural diffidence towards divers is shown, probably due to an enhanced availability of their prey as a result of divers’ contacts with the substrate.