TITLE:
The Influence of Environmental Factors on the Population Structure and Reproductive Biology of Idotea balthica basteri (Isopoda, Valvifera) of the Bizerte Lagoon (Northern Tunisia)
AUTHORS:
Wahiba Zaabar, Faouzia Charfi-Cheikhrouha, Mohamed Sghaier Achouri
KEYWORDS:
Population Structure, Reproductive Biology, Environmental Factors, Idotea balthica, Mediterranean Lagoon, Tunisia
JOURNAL NAME:
Open Journal of Ecology,
Vol.6 No.4,
March
30,
2016
ABSTRACT: The reproductive biology of a natural population of Idotea balthica
basteri (Pallas, 1772) collected from Menzel Jemil (Bizerte lagoon,
Tunisia) was monthly studied from October 2009 to October 2010. Besides water
temperature, salinity, turbidity, pH, and dissolved oxygen were measured. Based
on the state of differentiation of individuals, the population was divided into
8 categories. Their numbers depend on the one hand to intrinsic factors
imposed by the specimens and the structure of the population themselves, and to
extrinsic factors due to the variability of environmental conditions on the
other hand. Females were morphologically recognisable at smaller size than males.
Reproductive activity, which was reflected through the presence of ovigerous
females and juveniles, underwent fluctuations throughout the year, but it was
continuous. Moreover, salinity, temperature, nitrates, and plant biomass have a
noticeable effect on the fecundity and fertility. The Principal Component
Analysis also confirmed that the richness of the water in nitrates would be
favorable to fecundity and fertility of Idotea balthica basteri. However,
higher phosphate concentrations, in April and May seem to have a positive
effect on the sex ratio. Otherwise, the temperature would be responsible for
increasing the percentage of ovigerous females.