Habitats for large branchiopods in the agricultural landscape of the Mureş Floodplain Natural Park: how long will they last?

In the last two hundred years, the Mureş River Floodplain has suffered major changes caused by dike constructions, meander cutting, and by the transformation of the natural landscape into an agricultural one. In this environmental context, we wanted to find out the degree to which large branchiopod species still survive in the Mureş Floodplain area. Every stagnant aquatic habitat encountered in 2019 in the Mureş Floodplain Natural Park was sampled. For the habitats where more species co-occur, urgent preservation actions must be taken. Most of the species prefer open habitats and have survived in the wheel ruts on agricultural lands. In the absence of natural habitats, the importance of this habitat type becomes a major one. The forest advantages species related to shady habitats, such as Chirocephalus diaphanus. We have found several individuals in the park that showed black spots on their bodies, characteristic of the black disease of fairy shrimp. The presence of the disease only in the populations from wheel ruts suggests that vehicles which make these ruts, could be the carriers of the disease.

New Gynandromorph Records for Chirocephalus diaphanus (Branchiopoda, Anostraca, Chirocephalidae)

We report and describe new Chirocephalus diaphanus Prévost, 1803 gynandromorphs from Tunisia and review the literature of anostracan gynandromorphy and other, possibly associated, somatic aberrations, with comments on their evolutionary significance. Our material has three specimens that are specifically deformed on the left side of the head.

First record of Branchinectella media (Schmankewitsch, 1873) (Branchiopoda, Anostraca) in Romania

Romania is one of the most diverse countries for Anostraca in Europe. The Romanian Plain and the Black Sea coast are recognized as the most species-rich areas and harbour a high concentration of saline lakes and ponds. A short survey of ponds and small lakes was carried out in these areas of Romania during March 2019, with the aim of improving the knowledge of Anostraca diversity and distribution. Two species of Anostraca were found: Chirocephalus diaphanus romanicus Stoicescu, 1992, in Argeş County, and Branchinectella media (Schmankewitsch, 1873), in Constanţa County. The record of B. media is the first for Romania, increasing the known diversity of Anostraca to 17 species. This discovery highlights the high diversity of large Branchiopoda in the country.

Can large branchiopods shape microcrustacean communities in Mediterranean temporary wetlands?

It was recently suggested that large branchiopods may play a keystone role in temporary aquatic habitats. Using a microcosm experiment manipulating microcrustacean communities of Mediterranean temporary wetlands (Camargue, Southern France), we tested the following hypotheses: (i) large branchiopods (the notostracan Triops cancriformis and the anostracan Chirocephalus diaphanus) can limit microcrustacean densities through both competition and predation; (ii) notostracans create high suspended-matter concentrations through bioturbation, which can negatively impact microcrustaceans; and (iii) the outcome of these biotic interactions is more detrimental at high salinities. We found a strong predatory impact of T. cancriformis on active microcrustacean populations, but also on dormant populations through the consumption of resting eggs. They also preyed on anostracans and their conspecifics and can indirectly have a negative effect on microcrustaceans through bioturbation, probably by impeding filtering capacities. The presence of C. diaphanus also limited most microcrustacean groups, probably through competition and/or predation. We did not find a significant effect of the tested salinity range (0.5–2.5 g L–1) on the biotic interactions. Our study shows that large branchiopods can shape microcrustacean communities under a wide range of environmental conditions and confirms their potential for a keystone role, especially one of notostracans as top predators.

Pheromones inhibit the hatching of diapausing Anostraca (Crustacea: Branchiopoda)

Hatching of resting eggs of Streptocephalus torvicornis (Waga, 1942) and Branchipus schaefferi Fischer, 1834, two sympatric fairy shrimps, was tested using medium in which these two species and Chirocephalus diaphanus (Prévost, 1803) had been raised. The medium of adults inhibited the hatching of conspecific nauplii, even when diluted by 50% using distilled water. Streptocephalus torvicornis resting eggs hatch in the medium of C. diaphanus but not in the medium of B. schaefferi. Resting eggs of B. schaefferi hatched in low numbers in S. torvicornis medium, and in high numbers in that of C. diaphanus.There appears to be one or more substances associated with the presence of adults of conspecifics and sympatrics which exceed the influences of abiotic factors, such as light, pH, conductivity and osmotic pressure in fresh media. We propose that this substance(s) functions as a pheromone to inhibit further hatching once a population of adults is present.