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Vol. 49 No. 3, 2010
Relationships between the Hydrodynamics and Changes in
Copepod Structure on the Algerian Coast
Aziz
Hafferssas* and Rabia Seridji
Faculty
of Biological Sciences USTHB, BP 32, El Alia, Bab Ezzouar – Algiers,
Algeria
Aziz
Hafferssas and Rabia Seridji (2010)
We investigated the role of the Algerian Current on the structure of
the copepod community during June 1990 that covered an area between 1°E
and 5°E. In this area, 2 oligotrophic systems of different
origins (one related to the Atlantic flow, and the other related to
typical Mediterranean waters) and a frontal system were
identified. Environmental differences among the 3 zones were
related to changes in sea surface salinity, density, and phytoplankton
biomass (chlorophyll (Chl)-a concentrations). Three main copepod
assemblages were revealed to be distributed along well-defined
environmental gradients characterized by the distribution of physical
variables and Chl-a. The 1st group was located in the frontal
zone where the highest Chl-a concentration was observed at the
subsurface (> 1.5 mg/m3). This assemblage showed an important
increase of herbivorous species (Paracalanus parvus, Clausocalanus
arcuicornis, C. furcatus, Mesocalanus tenuicornis, and Eucalanus
elongatus) which were numerically 4 times more abundant (> 90%) than
in modified Atlantic water (MAW) and offshore surface Mediterranean
water (SMW) systems (< 30% and 35%, respectively). The 2nd
group occupied the inshore MAW system, and was characterized by a
typical neritic fauna (Acartia clausi, Euterpina acutifrons, Oithona
nana, and Temora stylifera). The 3rd group was composed of
several species (Scolecithricella dentata, S. vittata, Oncaea media,
Oncaea sp., Microstella rosea, Oithona helgolandica, Corycaeus ovalis,
C. brehmi, Corycaeus sp., Spinocalanus longicornis, Scolecithrix danae,
and Clausocalanus spp.) and was related to the largest region among the
sampled stations. In the deeper layer (200-500 m), 3 groups of
copepods showing different distribution patterns were identified using
a principal components analysis. No significant relationship
between the pattern of each group and the measured environmental
variables was identified in this study. However the small number
of studies of copepods in this area makes our contribution useful for
further global biogeographical studies in the western Mediterranean Sea.
Key words: Algerian coast, Hydrography,
Copepods, Zooplankton biomass, Environmental factors.
*Correspondence: E-mail:ahafferssas@usthb.dz
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