Isopod fauna, excluding Epicaridea, from the Strait of Gibraltar and nearby areas (Southern Iberian Peninsula)

A total of 42 isopod species from the Strait of Gibraltar and nearby areas were found, including the first record of Munna fabricii, Monodanthura maroccana, Campecopea hirsute, and Natatolana gallica from the Mediterranean; Synisoma nadejda and Uromunna petiti from the Atlantic; and Munna fabricii, Uromunna petiti, Monodanthura maroccana, Stellanthura cryptobia and Natatolana gallica from the Iberian waters. This article includes the previous records from the Iberian waters for all the species. The greatest number of species were found in Tarifa (16 species), located in the transition zone between the Atlantic Ocean and the Mediterranean Sea. According to depth, the distribution of species was as follows: 18 species were collected in the intertidal zone, mostly Dynamene edwardsi and Ischyromene lacazei; 33 species were found between 1 and 10 m, 13 species were found between 11 and 20 m, and 6 species were found between 21 and 28 m, mostly Janira maculosa. According to habitat, 16 species were collected on soft bottoms, 2 species on Zostera, and 22 species on algae substrata, mostly Halopteris, Asparagopsis and Cystoseira. The most diverse genus was Cymodoce (5 species). This paper contributes to the taxonomic, faunistic and biogeographical knowledge of the benthic communities from the Strait of Gibraltar and nearby areas.

Longer and less overlapping food webs in anthropogenically disturbed marine ecosystems: confirmations from the past

The human exploitation of marine resources is characterised by the preferential removal of the largest species. Although this is expected to modify the structure of food webs, we have a relatively poor understanding of the potential consequences of such alteration. Here, we take advantage of a collection of ancient consumer tissues, using stable isotope analysis and SIBER to assess changes in the structure of coastal marine food webs in the South-western Atlantic through the second half of the Holocene as a result of the sequential exploitation of marine resources by hunter-gatherers, western sealers and modern fishermen. Samples were collected from shell middens and museums. Shells of both modern and archaeological intertidal herbivorous molluscs were used to reconstruct changes in the stable isotopic baseline, while modern and archaeological bones of the South American sea lion Otaria flavescens, South American fur seal Arctocephalus australis and Magellanic penguin Spheniscus magellanicus were used to analyse changes in the structure of the community of top predators. We found that ancient food webs were shorter, more redundant and more overlapping than current ones, both in northern-central Patagonia and southern Patagonia. These surprising results may be best explained by the huge impact of western sealing on pinnipeds during the fur trade period, rather than the impact of fishing on fish populations. As a consequence, the populations of pinnipeds at the end of the sealing period were likely well below the ecosystem's carrying capacity, which resulted in a release of intraspecific competition and a shift towards larger and higher trophic level prey. This in turn led to longer and less overlapping food webs.