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The distribution of Branchiostoma senegalense (Acrania, Branchiostomidae) in the off‐shore shelf region off North West Africa
Author(s) -
Gosselck Fritz
Publication year - 1975
Publication title -
internationale revue der gesamten hydrobiologie und hydrographie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 52
eISSN - 1522-2632
pISSN - 0020-9309
DOI - 10.1002/iroh.19750600204
Subject(s) - shore , detritus , population , biology , macrobenthos , geography , biomass (ecology) , oceanography , fishery , ecology , geology , demography , sociology
During investigations on the macrobenthos between 17° N and 26° N on the North West African continental shelf, abundant stocks of Branchiostoma were found off Spanish Sahara (23° N‐25° N), on the d'Arguin Bank (21° N‐20° N) and off Gambia (12° N‐13° N). The lancelets were identified as Branchiostoma senegalense (WEBB, 1955) by means of statistical analyses. The lancelet populations occur at dephts down to about 40 m. Deeper regions are probably avoided because of the excessively high detritus content. Favourable environmental factors such as temperature, composition of the sediment and food supply permit high lancelet abundancies. Up to 9000 animals'm 2 were found in the population off Spanish Sahara. Rough calculations showed that the lancelet population comprises about 6 × 10 12 individuals with a biomass of 1.5 million tons. The potential natality amounts to about 45 × 10 15 larvae a year.