Spatial variability of the mesozooplankton biomass and ichthyoplankton in the Canary region, in autumn 1991

Abstract

In this paper, we study whether the variability introduced in the Canary region by the Canary Islands on perturbing the general flow of the Canary Current and trade winds, and by the Northwest African upwelling, is manifested in the mesozooplankton biomass distribution and ichthyo- plankton population. Two transects were sampled and two stations were occupied for 24 h during the first part of the cruise Canarias 9110. One transect and one station were located to the north, upstream of the Canary Islands, in the 'non-perturbed' zone, and the other transect and station were to the south, downstream of the islands, in the 'perturbed' zone. Oceanographic conditions, as represented by the vertical temperature structure, changed both latitudinally, between upstream unperturbed and downstream perturbed conditions, and longitudinally, between upwelling and oceanic situations. However, differences were evident only in mesozooplankton biomass and in the latitudinal sense. Likewise, the results obtained suggest that (i) there is an interconnection between the neritic fish populations of the Macaronesian archipelagos, in a north-south sense and in a southerly direction, by means of the transport of fish larvae by the Azores and Canary currents, and (ii) this interconnection could affect both those species whose larvae are well adapted for a long survival in the pelagic environ- ment, possessing morphological specializations, and those whose larvae do not present these charac- teristics.