Parasitization of monkey goby, Neogobius fluviatilis (Pallas, 1814) (Actinopterygii: Gobiidae), at localities with different salinity levels

Parasitism of monkey goby, Neogobius fliviatilis, was assessed at three brackish water localities with different salinity levels (Gulf of Odessa, Khadzibey Estuary, Lake Kytay) and one freshwater site along the Lower Danube River (Vidin). A total of 25 parasite taxa were identified, with minimum parasite richness recorded in the Khadzhibey Estuary (three species) and the maximum along the Lower Danube (11 species). Parasite richness in the mesohaline Gulf of Odessa and oligohaline Lake Kytay was lower, but still relatively high compared to the Khadzibey Estuary. Our study indicates that freshwater populations of monkey goby host richer and more abundant parasite communities than those inhabiting brackish waters with (more or less) stable salinity. Unstable abiotic conditions that probably affected the parasite’s intermediate hosts contributed to the reduction in parasite species in the estuarine zone of the Danube.

Bioaccumulation of Heavy Metals and Implications Associated with Consumption of the Thinlip Mullet (Liza ramada) Collected from Sites of Varying Salinity

The bioaccumulation of heavy metals (Fe, Cu, Zn, Mn, Pb, Cd, Co, and Ni) were assessed in tissues (gills, liver, and muscles) of the thinlip mullet (Liza ramada) collected from three aquatic habitats varying in salinity in Egypt (freshwater, brackish, and offshore sites). In the freshwater site, metals accumulate in order of gills > liver > mussels with exception to Cu, Zn and Ni (liver > gills > mussels). In the brackish site, the order of metal accumulation for Fe, Cu, Zn, and Co were: liver > gills > mussels, and for Ni, Pb, and Mn were: gills > liver > mussels, while; Cd accumulated in order of mussels > gills > liver. In offshore site, Metals accumulates in order of: liver > gills > mussels except for Mn and Ni (gills > liver > mussels) and Cd (mussels > gills > liver).The overall metal concentrations for the three sites were ranked in the order of Fe > Mn > Zn > Cu > Pb > Cd > Co > Ni. There were significant differences between sites for Cu and Co, and between fish organs for Pb, Cd, Co, and Ni. Strong positive correlations were found between Fe and Zn (P<0.001), Fe and Pb (P<0.001), Fe and Mn (r= P<0.001), Mn and Ni (P<0.001), and Cd and Ni (r= P<0.01). Significant positive correlations (p<0.05) were observed between Zn with Co and Fe with Ni. Target hazard quotient (THQ) values for Pb, Cd, Co, and Ni were higher than 1 for the three sites, which suggests that adverse health effects might arise from the consumption of these fish. The estimated daily intake (EDI) values for Ni and Cd were higher than the recommended levels, indicating health effects; however, the values for rest of the metals were lower than the recommended EDI levels, suggesting that they are unlikely to pose a health risk.

THÀNH PHẦN LOÀI, PHÂN BỐ VÀ MỐI QUAN HỆ GIỮA QUẦN XÃ CÁ BỐNG VỚI CÁC YẾU TỐ MÔI TRƯỜNG VÀ SINH CƯ Ở VÙNG HẠ LƯU SÔNG THU BỒN, TỈNH QUẢNG NAM

The study was conducted at three sites representing large variation in gradient of salinity from very low (Thanh Ha) to medium (Cam Nam) and high (Cam Thanh) in rainy (12/2015) and dry seasons (6/2016) in downstream area of Thu Bon river. At each site, goby species were sampled with traps and measurements of enviromental factors (pH, temperature, salinity, dissolved oxygen) and habitats (cover of freshwater weeds-grass, nypa palm-seagrass, sand-mud, mud-sand) were conducted at the 3 sites mentioned above. A total of 14 species belonging to 2 families Gobiidae (8 species) and Eleotridae (6 species) were recorded in rainy and dry seasons, in which the brackishwater site (Cam Thanh) supported the higher number of species (12 species) compared to the transitional site (Cam Nam: 6 species) and the freshwater site (Thanh Ha: 10 species). Results of annalyzing canonical correspondence between goby communities and the enviromental factors and habitats indicate that the distribution of goby community was mainly influenced by pH, salinity, dissolved oxygen and benthic cover of freshwater seaweeds-grass.

High Diversity of Magnetotactic Deltaproteobacteria in a Freshwater Niche

ABSTRACTKnowledge of the diversity of magnetotactic bacteria in natural environments is crucial for understanding their contribution to various biological and geological processes. Here we report a high diversity of magnetotactic bacteria in a freshwater site. Ten out of 18 operational taxonomic units (OTUs) were affiliated with theDeltaproteobacteria. Some rod-shaped bacteria simultaneously synthesized greigite and magnetite magnetosomes.