Dietary carotenoids have been shown to confer immunological benefits to some species of animals in which males also use these pigments to attract mates. Thus, the potential exists for an allocation trade-off between the sexual and immunological functions of carotenoids. Food availability may also influence immune system function. The present study examined the effects of carotenoid and food availability on the resistance of male guppies ( Poecilia reticulata Peters) from four wild populations to the parasite Gyrodactylus turnbulli Harris. Intermediate levels of carotenoid ingestion resulted in the lowest parasite loads, which suggests that carotenoids strengthen parasite resistance at low levels but either benefit parasites or suppress host immunity at high levels. Males raised on the high-food level initially had fewer parasites, suggesting heightened innate immunity relative to males raised on the low-food level. Over the course of the experiment, however, the high-food males supported higher parasite population growth rates than the low-food males. The results obtained emphasize the importance of evaluating the effects of diet on multiple aspects of immune system function, and caution against assuming that positive effects of carotenoids on immunity in one context will automatically translate to other contexts.

The presence of fin whales in the Mediterranean Sea has been documented since ancient times. In spite of this, reliable information on their ecology and distribution is limited to the north-western part of the basin. Recent genetic studies have demonstrated that Mediterranean fin whales comprise a separate population with very limited gene flow with their North Atlantic co-specifics. Although both published and anecdotal information reports their presence in the south central Mediterranean during winter, there is no information on habitat use. In February 2004, a 14-day boat survey was carried out in the waters surrounding the island of Lampedusa, where fin whales occur at this time of the year. A total of 20 fin whale groups (average group size two animals) were encountered. In each encounter the animals were engaged in surface feeding activity. From plankton samples and underwater video, the prey species was identified as the Euphausiid, Nyctiphanes couchi. The information obtained suggests that this area may be an important winter feeding ground for fin whales. The results represent significant new information on fin whale ecology in the Mediterranean, with associated conservation and management implications.

The giant devil ray Mobula mobular is the only mobulid species regularly present in the Mediterranean Sea. The spatial ecology and biology of this species are poorly known, and given its high bycatch mortality, low reproductive capacity, and limited range, it is listed as Endangered (A4d) on the IUCN Red List. Most of the information concerning this species has been obtained through bycatch data and opportunistic sightings. To inform conservation and management actions, it is necessary to conduct research on the behavior of giant devil rays. This study is the first attempt to systematically describe the diving behavior of this species. Three specimens were tagged with popup satellite tags in the Messina Strait (central Mediterranean Sea) during summer 2007. Two tags were programmed to detach after 120 d and 1 after 60 d. The data revealed that these fish dove to depths between 600 and 700 m. However, they spent most of their time (81.5%) between the surface and 50 m, in waters with temperatures between 20 and 29°C. The preference for shallow depth and warm surface waters exposes this species to threats such as accidental captures in driftnets and surface longlines.

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Errina aspera is the only species belonging to the family Stylasteridae known from the Mediterranean Sea. The distribution of this species includes the Messina Strait, the Gibraltar Strait and the Atlantic coast of Morocco. In spite of the taxonomic and biogeographical importance of this species, no studies were conducted on its population structure in the Messina Strait. Here we report a study carried out with the aid of a ROV on a horizontal transect 350 m long at a depth comprised between 83 and 105 m where an extremely dense population of this stylasterid (101.4 ± 13.3 m−2) was recorded. The main components of the benthic community other than E. aspera are the coralline alga Lithothamnion philippii and the white zoanthid Epizoanthus sp. The colonies of E. aspera have a height ranging between 1.2 and 18.8 cm (4.1 ± 0.1 cm on average); they generally show a bi-dimensional, fan shaped morphology, but three-dimensional, brush-like specimens are also observed. The size–frequency distribution of the colony height is unimodal with a mode in the classes of 3–5 cm and a long tail of rare large colonies suggesting that the current may act as a limiting factor for the colony growth. The association with the gastropod ovulid Pedicularia sicula is confirmed.