Ichthyofauna assemblages from two unexplored Atlantic seamounts: Northwest Bank and João Valente Bank (Cape Verde archipelago)

Pedro Monteiro,Jorge M.S Gonçalves,Daniel Ribeiro,João Bispo,José A Silva

doi:10.3989/scimar.2008.72n1133

Pedro Monteiro, Jorge M.S Gonçalves + Show 3 more

Open Access

https://doi.org/10.3989/scimar.2008.72n1133

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Abstract

Underwater censuses by divers were used to study the fish assemblages from two unexplored Atlantic seamounts in the Cape Verde archipelago. Fifty three species of 27 families were recorded: 27 in Northwest Bank and 46 in Joao Valente Bank. Northwest Bank had dense schools, while Joao Valente Bank had higher species richness and smaller schools. Both seamounts were dominated mainly by coastal species directly depending on seabed habitat (Demersal or benthopelagic). Of the 53 fish species recorded, 22.6% were of continental African origin, while 9.4% and 5.7% were endemic of the Cape Verde Islands and of the Macaronesia province, respectively. Most species (64.2%) had a very wide biogeographic distribution: cosmopolitan (22.6%), amphi-Atlantic (28.3%) and Atlantic-Mediterranean (13.2%). Northwest Bank and Joao Valente Bank may have a permanent fish community supported by various oceanographic-topographic interactions. Joao Valente Bank seems more diverse, which is probably associated with algae cover and with a larger area providing additional suitable and more varied habitats. The geographic proximity to the coast and the presence of oceanic and/or oceanodromous species suggests that the upper part of these seamounts may act both as attraction points and as “stepping-stones” for the dispersal of coastal species.

Highlights

Seamounts are elevations similar to those located in continents, with peaks below sea level rising 1000 m or more from the sea floor (Kitchingman and Lai, 2004)
SUMMARY: Underwater censuses by divers were used to study the fish assemblages from two unexplored Atlantic seamounts in the Cape Verde archipelago
Of the 53 fish species recorded, 22.6% were of continental African origin, while 9.4% and 5.7% were endemic of the Cape Verde Islands and of the Macaronesia province, respectively

Summary

Introduction

Seamounts are elevations similar to those located in continents, with peaks below sea level rising 1000 m or more from the sea floor (Kitchingman and Lai, 2004). Northwest Bank extends in a SWNE direction and is formed by two peaks located 10 nm offshore of the westernmost island of the archipelago (Santo-Antão island), rising from 2500 m to close to 35 m below the surface (Fig. 1). João Valente Bank is located about 25 nm from Maio Island and 20 nm from Boavista Island, the easternmost island of the archipelago. It stands on a relatively shallow sea platform (around 100 m deep) that rises from 1000 m, with the peak 10 m below the surface (Fig. 1). Hydro-dynamic conditions over seamounts could create particular ecological processes and host high fish diversity and endemism (Goldner and Chapman, 1997; Beckmann and Mohn, 2002; Trasvinã-Castro et al, 2003)

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