Distribution patterns of ichthyoplankton communities in different ecosystems of the northeast atlantic

Abstract

Results are presented of an extensive ichthyoplankton survey that covered the continental slope, the offshore banks and oceanic regions west of Ireland. Oceanographic measurements revealed domes of cold, less saline water over the Porcupine, Rockall and Faroese Banks, constituting Taylor columns. The most species-rich stations were those found on and close to the offshore banks and the shelf edge. Larvae found in these areas were mainly from demersal fish species, including some commercial species such as haddock Melanogrammus aeglefinus, lemon sole Microstomus kitt (Walbaum, 1792), ling Molva molva (L.) and witch Glyptocephalus cynoglossus (L.). The deep water stations of the Rockall Trough and the north and west stations off the Rockall and Hatton Banks were characterized by a low number of species and high numbers of individuals of mesopelagic species such as Maurolicus muelleri and Benthosema glaciale. Results from multivariate statistical analysis confirmed that species compositions varied significantly at different sites and were related to environmental conditions, whereby sites of similar temperature, salinity and bottom depth harboured similar species assemblages. Generalized additive mixed modelling was used to model the relationship between species richness and environmental variables and confirmed that there was a significant negative relationship between species richness and bottom depth indicating that the offshore banks and the slope stations present favourable habitats for a large number of species.