Resting eggs bank and their hatching pattern in two co-occuring anostracans Phallocryptus spinosus (Milne-Edwards, 1840) and Branchinectella media (Schmankewitsch, 1873) (Crustacea) from saline lakes of the Aurès region (Northeastern Algeria)

Abstract

Phallocryptus spinosus (Milne-Edwards, 1840) and Branchinectella media (Schmankewitsch, 1873) are two anostracan species co-occurring in several saline lakes of the eastern steppic zone of Algeria. Both species produce resting eggs to persist in their temporary and unstable habitats, constituting a resting eggs bank. B. media has a restricted distribution worldwide and it is known to prefer cold temperatures (16 °C max). Resting egg banks and hatching patterns of both species have been assessed in seven saline lakes. Results showed that densities of P. spinosus resting eggs were always higher than those of B. media, whatever the lake (F = 4.66, P = 0.0005). They range between 93000 ± 75 and 1495000 ± 366.5 resting eggs.m-2 for P. spinosus, and between 670 ± 30 and 365000 ± 268 resting eggs.m-2 for B. media. Hatching percentages of eggs incubated at temperatures of 16 °C and 22 °C, and salinities of 0 and 5 psu, showed that 16 °C and 5 psu was the most suitable combination for B. media, where 38.88 ± 1.93% of eggs hatched under these conditions. For P. spinosus, 81.11 ± 1.92% of eggs hatched at 22 °C and 5 psu. Resting eggs diameters measurements of both species as well as scanning electron micrographs of B. media are provided.