RESUMEN
The deep sea plays a critical role in global climate regulation through uptake and storage of heat and carbon dioxide. However, this regulating service causes warming, acidification and deoxygenation of deep waters, leading to decreased food availability at the seafloor. These changes and their projections are likely to affect productivity, biodiversity and distributions of deep-sea fauna, thereby compromising key ecosystem services. Understanding how climate change can lead to shifts in deep-sea species distributions is critically important in developing management measures. We used environmental niche modelling along with the best available species occurrence data and environmental parameters to model habitat suitability for key cold-water coral and commercially important deep-sea fish species under present-day (1951-2000) environmental conditions and to project changes under severe, high emissions future (2081-2100) climate projections (RCP8.5 scenario) for the North Atlantic Ocean. Our models projected a decrease of 28%-100% in suitable habitat for cold-water corals and a shift in suitable habitat for deep-sea fishes of 2.0°-9.9° towards higher latitudes. The largest reductions in suitable habitat were projected for the scleractinian coral Lophelia pertusa and the octocoral Paragorgia arborea, with declines of at least 79% and 99% respectively. We projected the expansion of suitable habitat by 2100 only for the fishes Helicolenus dactylopterus and Sebastes mentella (20%-30%), mostly through northern latitudinal range expansion. Our results projected limited climate refugia locations in the North Atlantic by 2100 for scleractinian corals (30%-42% of present-day suitable habitat), even smaller refugia locations for the octocorals Acanella arbuscula and Acanthogorgia armata (6%-14%), and almost no refugia for P. arborea. Our results emphasize the need to understand how anticipated climate change will affect the distribution of deep-sea species including commercially important fishes and foundation species, and highlight the importance of identifying and preserving climate refugia for a range of area-based planning and management tools.
RESUMEN
Cysts of metacercariae were obtained on 2 dates from juvenile sole Solea solea sea-sampled in an area of mussel cultivation (Pertuis Charentais, Bay of Biscay, France). An initial assessment of parasite genus and infestation level was based on 192 cysts extracted from 2 fish samples, taken in August (n = 20) and December 2000 (n = 14). Our results confirmed the sole as second intermediate host of bucephalid trematodes of the genus Prosorhynchus, which has not previously been noticed in Atlantic stocks. Prevalence, ca. 65% on both dates, indicated an substantial infestation of these small fish, with a mean abundance of parasites increasing from August (3.3 +/- 1.1) to December (8.1 +/- 3.4). Cysts were localised in all body parts of the host, and positioning varied depending on sampling date. However, the cephalic area was always the most infested (72.7 and 49.1% in August and December, respectively). Parasite measurements suggested a protracted infestation process, which may be initiated in spring during sole settlement. Most of the largest metacercariae had the rhynchus characteristics of P. crucibulum, though the possibility of them being other species (P. squamatus, P. aculeatus) could not be excluded. As Mytilus edulis is the first intermediate host of Prosorhynchus spp., possible relationships between mussel culture and sole parasitosis are discussed.