Impact of a dam construction on the intertidal environment and free-living nematodes in the Ba Lai, Mekong Estuaries, Vietnam.

The impact of high siltation and accumulation of organic and waste material in the intertidal of the dammed Ba Lai River in Vietnam as part of the Mekong estuarine system was investigated by means of marine free-living nematodes. Nutrients content (nitrate, ammonium, total phosphorus, total nitrogen), total suspended solids, total organic carbon, coliform, bacteria E. coli, pH, dissolved oxygen, total dissolved solids, methane and hydrogen sulfide concentration, and the nematode communities were characterized in sediment at selected stations along the river above and below the dam. Our results found elevated methane concentrations at the upstream side of the dam while hydrogen sulfide concentrations found to be highest in the downstream side of the dam. Furthermore, methane and hydrogen sulfide concentrations were correlated to nematode community characteristics such as trophic composition densities and genera composition. There was a clear difference between the communities above and below the dam. The discontinuous nematode community distribution indicated that the Ba Lai River is impacted by dam construction. Potentially the high deposition and eutrophication could turn the area into a methane-rich area related to predicted impact on nematodes.

Review of the genus Arhaconortus Belokobylskij, 2000 (Hymenoptera: Braconidae: Doryctinae), with description of three new species from Vietnam.

In the present study, the genus Arhaconotus is revised and keyed with three species of this genus from Vietnam were described and fully illustrated as new for science, viz.Arhaconotus belokobylskiji Long,sp. nov., A. hoabinhicus Long,sp. nov. and A. longicaudatus Long,sp. nov., and one species, A. hainanensis Tang & Chen, 2010 newly recorded for Vietnams braconid fauna. Up to know, a total of seven species of Arhaconotus are described, a key to all the already known Arhaconotus species is provided. Comparative morphological characters of Arhaconotus species were also discussed.

First record of the genus Testudobracon Quicke, 1986 (Hymenoptera: Braconidae: Braconinae) in Vietnam, with description of four new species.

Five species of the genus Testudobracon Quicke, 1986 in Vietnam were recognized, and four new species, viz. Testudobracon alius Long, sp. nov., Testudobracon descensus Long, sp. nov., Testudobracon imitator Long, sp. nov., and Testudobracon phiaoacus Long & PQMai, sp. nov. are described and fully illustrated. Additionally, the genus Testudobracon and one species, Testudobracon flavus Tang, Chen & He, 1997, are newly recorded for the Vietnam's braconid fauna. A checklist of the already known of Testudobracon species is provided, a key to Vietnamese species of the genus Testudobracon in Vietnam, their in-country distribution, and differentiation of the known similar species are also given.