In:
Journal of the Marine Biological Association of the United Kingdom, Cambridge University Press (CUP), Vol. 93, No. 6 ( 2013-09), p. 1625-1640
Abstract:
Many Thecosomata (Gastropoda) produce an aragonite shell and are potentially threatened by the increasing ocean acidification. Information about these species is very important for future monitoring of the fate of this group. This paper investigates the distribution, species composition and trophic role of Thecosomata along a transect from the coast into the open ocean off Walvis Bay, Namibia, in September 2010 and January/February 2011. Twenty species were detected, but three taxa ( Limacina bulimoides , Limacina inflata and Desmopterus papilio ) dominated the community with more than 80% of the total standing stock. Diel vertical migration was observed for both Limacina taxa with higher concentrations in surface waters during night. Desmopterus papilio revealed almost no day/night differences. The highest diversities and abundances were detected at the slope and offshore stations, indicating the oceanic preference of this group; some taxa aggregated at the shelf–open ocean interface. δ 15 N measurements confirmed the first trophic level of this group; however, significant differences were detected between seasons with higher values in February 2011. This can be related to differences in seston values as the primary food source. Possible biogeochemical causes for these differences like an exhaustion of the nitrate pool or denitrification processes under suboxic conditions are discussed.
Type of Medium:
Online Resource
ISSN:
0025-3154
,
1469-7769
DOI:
10.1017/S0025315413000052
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
2013
detail.hit.zdb_id:
1491269-7
detail.hit.zdb_id:
281325-7
SSG:
12
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