|Diel changes of the benthic boundary layer macrofauna over coarse sand sediment in the western English Channel|
Zouhiri, S.; Dauvin, J.-C. (1996). Diel changes of the benthic boundary layer macrofauna over coarse sand sediment in the western English Channel. Oceanol. Acta 19(2): 141-153
In: Oceanologica Acta. Elsevier/Gauthier-Villars: Montreuil. ISSN 0399-1784, more
Bottom; Temperature; Crustacea [WoRMS]; Marine
|Authors|| || Top |
- Zouhiri, S.
- Dauvin, J.-C., more
The Benthic Boundary Layer (BBL) macrofauna over a coarse sand community at Trezen Vraz (western English Channel) was sampled with a modified Macer-GIROQ hyperbenthic sledge to analyse its diel changes on two occasions, in November 1988 (9 hauls), and in July 1990 (11 hauls). Species composition of the fauna, swimming activities, daily vertical migrations, biomass of the principal taxa, and biomass exchanges between the BBL, the benthos, and the pelages were studied. Sixty-one taxa in November and 129 taxa in July were sorted, counted, and classified into three groups: mesozooplankton, macrozooplankton, and hyperbenthos. In the mesozooplankton, copepods and crustacean larvae were very abundant in July. In the macrozooplankton, the chaetognath Sagitta elegans was abundant in both sets of samples, while the euphausiids were only abundant in November, and fish larvae and the amphipod Apherusa clevei were only abundant in July. In both sets of samples the most abundant taxon of the hyperbenthos was the mysid Anchialina agilis. The densities of all collected taxa fluctuated with daily vertical migrations: higher densities of mysids and euphausiids were present in daytime, whereas amphipods and decapods were more abundant at night. The biomasses in each haul varied from 72 to 303 mg/100 m³ (mean: 154 mg/100 m³) in November, and from 160 to 1943 mg/100 m³ (mean: 638 mg/100 m³) in July. Biomass exchanges between pelages, BBL and benthos appeared important around sunset and sunrise.