Search results for "Fora"
showing 10 items of 1086 documents
REPRODUCTIVE SUCCESS OF EURASIAN TREECREEPERS,CERTHIA FAMILIARIS,LOWER IN TERRITORIES WITH WOOD ANTS
1999
Few studies have considered the effects of interspecific competition between distantly related taxa on the reproductive success of individuals. We compared the food supply, laying date, clutch size, and breeding success of a small double-brooded passerine bird, the Eurasian Treecreeper (Certhia familiaris) between territories with or without col- onies of red wood ants (Formica rufa group) during four years. Both the wood ants and Eurasian Treecreepers forage on tree trunks and utilize the same food resources. It has been shown that the wood ants are able to depress the available food supply for the treecreepers and interfere with their foraging behavior. We found that food abundance was lo…
Diel vertical movements by lotic mayfly nymphs under variable predation risk
1999
Summary 1. The diel foraging periodicities of two grazing mayfly (Ephemeroptera) nymphs, Heptagenia dalecarlica and Baetis rhodani, under variable fish (European minnow) predation risk were examined in a series of laboratory experiments. 2. Heptagenia dalecarlica were almost exclusively nocturnal in their use of feeding areas on stone tops. There was a sharp increase in the proportion of nymphs out of refuge at nightfall, both in the control and fish-odour treatments. In a treatment with freely moving fish, H. dalecarlica decreased their activity during both the day and night. In feeding trials with three freely foraging minnows, nymphs were completely safe when they had access to refuges b…
Behavioural interactions in stream food webs: the case of drift-feeding fish, predatory invertebrates and grazing mayflies
1999
Summary 1. We examined direct and indirect behavioural responses of grazing mayfly nymphs (Baetis rhodani) to predation risk from a drift-feeding fish (European minnow; odour manipulated), and two types of invertebrate predators, Diura bicaudata (stonefly) and Rhyacophila nubila (caddis larva). We also assessed the direct responses of the invertebrate predators to fish chemicals. 2. Based on diel gut content periodicity, D. bicaudata nymphs were strongly nocturnal foragers. R. nubila was also nocturnal, but only in a fish stream; in a stream lacking fish, their gut contents did not vary significantly on a diel basis. In the laboratory, Diura was nocturnal even in the absence of fish and alm…
Complementary methods assessing short and long-term prey of a marine top predator ‒ Application to the grey seal-fishery conflict in the Baltic Sea.
2019
The growing grey seal (Halichoerus grypus) population in the Baltic Sea has created conflicts with local fisheries, comparable to similar emerging problems worldwide. Adequate information on the foraging habits is a requirement for responsible management of the seal population. We investigated the applicability of available dietary assessment methods by comparing morphological analysis and DNA metabarcoding of gut contents (short-term diet; n = 129/125 seals, respectively), and tissue chemical markers i.e. fatty acid (FA) profiles of blubber and stable isotopes (SIs) of liver and muscle (mid- or long-term diet; n = 108 seals for the FA and SI markers). The methods provided complementary inf…
Artificial selection for predatory behavior results in dietary niche differentiation in an omnivorous mammal
2021
AbstractThe diet of an individual is a result of the availability of dietary items and the individual’s foraging skills and preferences. Behavioral differences may thus influence diet variation, but the evolvability of diet choice through behavioral evolution has not been studied. We used experimental evolution combined with a field enclosure experiment to test whether behavioral selection leads to dietary divergence. We analysed the individual dietary niche via stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) in the hair of an omnivorous mammal, bank vole, from 4 lines selected for predatory behavior and 4 unselected control lines. Predatory voles had higher hair δ15N values than…
Source area determination of aeolian sediments at Jandia Isthmus (Fuerteventura, Canary Islands)
2010
Abstract The Jandia Isthmus (Fuerteventura, Canary Islands) is a complex aeolian system composed of Pliocene and Pleistocene marine deposits, which are partially covered of carbonate crusts, palaeosols and sand sheets. The area has been greatly influenced by climate changes during the Quaternary. Nowadays this area presents an arid landscape dominated by the aeolian processes. Grain size, mineralogical and micropalaeontological analyses have been carried out to identify the source area of these wind-blown materials, considering five possible sources: windward beaches, Pliocene dune cliffs, Upper Pleistocene aeolian deposits, carbonate crusts and basaltic outcrops. Each one of these analyses…
A SMALL INVADER CONQUERS SICILY: AMPHISTEGINA LOBIFERA (FORAMINIFERA: AMPHISTEGINIDAE)
2018
The highly invasive Amphistegina lobifera (Larsen, 1976), a benthic foraminiferal species native to the Red Sea, has colonized the Eastern Mediterranean through the Suez Canal and altered the native community structure. More recently, it has been reported from Malta and the Pelagian Islands within the Sicily channel. Here, we report new records from the southern coasts of Sicily, where we found it abundant both in the soft-bottom sediment and as epiphyt on algae. The occurrence of A. lobifera in Pantelleria and Favignana islands represents the Mediterranean westernmost record of this non-indigenous species.
Assessing the effect of mercury pollution on cultured benthic foraminifera using DNA metabarcoding and morphological approaches
2016
Heavy metals such as mercury (Hg) occur in ecosystems from both natural sources and human activities, with large variations in concentrations and pose a significant health hazard through bioaccumulation and biomagnification. The aim of this experimental study is to assess the impact of different concentrations of Hg through time on the diversity of cultured benthic foraminifera. Tanks with concentrations of Hg up to 100 ppm were considered. Mesocosms containing 1-cm-thick sediment from each tank were subsampled at pre-established time intervals for geochemical (Hg content), morphological and molecular analyses. Morphological analyses were based on both Rose Bengal and the CellTracker Green …
High-frequency modification of the central Mediterranean seafloor environment over the last 74 ka
2022
Here we present a high-resolution record of benthic foraminiferal assemblages for the last 74 kyr from the Sicily Channel Ocean Drilling Program Leg 160 Site 963. Benthic foraminiferal results are compared with geochemical (benthic and planktic δ18O and δ13C) and calcareous plankton data, previously acquired on the same marine core sediments. Within the succession, three benthic foraminifera compositional zones were defined. Temporal changes in the assemblages are interpreted in the context of the modification of subtropical and temperate climate systems that affected the Mediterranean thermohaline circulation. A close connection between bottom conditions in the Sicily Channel and eastern M…