Resting eggs bank and their hatching pattern in two co-occuring anostracans Phallocryptus spinosus and Branchinectella media (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 wide and scattered distribution area, 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 93,000 ± 75 and 1,495,000 ± 366.5 resting eggs m⁻² for P. spinosus, and between 670 ± 30 and 365,000 ± 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, since 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.