SEASONAL VARIATIONS IN SIZE, WEIGHT AND BIOCHEMICAL COMPOSITION OF DONAX TRUNCULUS L. (PELECYPODA, MOLLUSCA) FROM ABU KIR BAY AND ROSETTA REGIONS

SEASONAL VARIATIONS IN SIZE, WEIGHT AND BIOCHEMICAL
COMPOSITION OF DONAX TRUNCULUS L. (PELECYPODA,
MOLLUSCA) FROM ABU KIR BAY AND ROSETTA REGIONS
NAlM M. DOWIDAR AND F. E. EL-NADY

Department of Oceanography, Faculty of Science, University of

Alexandria, Egypt

ABSTRACT
Seasonal variations in size. weight and biochemical fractions
(tota1 protei n, 1i pi d, carbohydrate and ash) of the edi b1e clam
Donax trunculus were studied in two ecologically different nk-hs
in the vicinity of Alexandria i.e Abu-Kir Bay and Rosetta estuary.
The population of Rosetta was characterized by smaller size and
smaller dry weight. high water content and larger wet weight
compared to that of Abu Kir Bay. Rosetta animals reached maturity
(maximum size and weight) in spr1ng and probably breed during
this season whil e those from Abu- Ki r Bay breed in SUlllller. The
seasonal and regional variations in protein and lipid were also
significant. The average protein content amounted to 65.31
and 61;01 of the dry body weight in Abu-Kir Bay and Rosetta
estuary respectively. A significant inverse correlation between
protei.n and lipid was demonstrated. The average lipid ..mountell
to 17.1 1 in Rosetta and 13.1 1 in Abu Kir-Bay.
The seasonal and spatial variations in these parameters are
discussed in relation to the prevailing environmental conditions.