Toxic Effects of Methylene Blue on the Growth, Reproduction and Physiology of Daphnia magna.

Methylene blue (MB) is a disinfectant used in aquaculture to prevent and treat fish diseases. However, the release of MB can pose a risk to the receiving water bodies. Zooplankton are the most sensitive organisms among aquatic life. Hence, this study examined the acute and chronic toxic effects of MB on zooplankton using Daphnia magna (D. magna) as a test organism to provide basic data for risk assessment. The results show that 48 h-EC50 and 24 h-LC50 were 61.5 ± 2.3 and 149.0 ± 2.2 µg/L, respectively. Chronic exposure to MB affected the heart rate, beat frequency of the thoracic limbs, and reproductive ability of D. magna at environmental concentrations higher than 4.7 µg/L. The cumulative molts, time to production of the first brood, and total number of living offspring were affected at different MB concentrations, while "abortions" were observed in high-exposure groups. The activity of superoxide dismutase was increased, while glutathione S-transferase activity was stimulated at low concentrations and inhibited at high concentrations. In addition, the malondialdehyde content increased with increasing concentrations of MB. Our findings demonstrate the impact of MB on the reproduction and growth of freshwater species, as well as their physiological responses. These results have implications for establishing guidelines on the use of MB in aquaculture and setting discharge standards.

Effects of Enrofloxacin on the Epiphytic Algal Communities Growing on the Leaf Surface of Vallisneria natans.

Enrofloxacin (ENR) is a member of quinolones, which are extensively used in livestock farming and aquaculture to fight various bacterial diseases, but its residues are partially transferred to surface water and affect the local aquatic ecosystem. There are many studies on the effect of ENR on the growth of a single aquatic species, but few on the level of the aquatic community. Epiphytic algae, which are organisms attached to the surface of submerged plants, play an important role in the absorption of nitrogen and phosphorus in the ecological purification pond which are mainly constructed by submerged plants, and are commonly used in aquaculture effluent treatment. Enrofloxacin (ENR) is frequently detected in aquaculture ponds and possibly discharged into the purification pond, thus imposing stress on the pond ecosystem. Here, we performed a microcosm experiment to evaluate the short-term effects of pulsed ENR in different concentrations on the epiphytic algal communities growing on Vallisneria natans. Our results showed an overall pattern of "low-dose-promotion and high-dose-inhibition", which means under low and median ENR concentrations, the epiphytic algal biomass was promoted, while under high ENR concentrations, the biomass was inhibited. This pattern was mainly attributed to the high tolerance of filamentous green algae and yellow-green algae to ENR. Very low concentrations of ENR also favored the growth of diatoms and cyanobacteria. These results demonstrate a significant alteration of epiphytic algal communities by ENR and also spark further research on the potential use of filamentous green algae for the removal of ENR in contaminated waters because of its high tolerance.

Annotated Checklist of Chinese Cladocera (Crustacea: Branchiopoda). Part II. Order Anomopoda (families Macrotrichidae, Eurycercidae and Chydoridae).

About 114 "species" of Macrothrichidae, Eurycercidae, and Chydoridae (Cladocera, Anomopoda), belonging to 39 genera, have been reported from China, with 14 species in 6 genera in Macrothrichidae, 2 species in one genus in Eurycercidae, and 98 species in 31 genera in Chydoridae. In total, 203 species in 62 genera, 13 families and 4 orders have so far been reported from the country. Of these, 187 are tentatively considered as valid, while 16 are incertae sedis. In reality, many records hide taxonomic problems that remain to be settled. Up to 10 percent of this fauna might be endemic at the species level, but we expect this number to increase pending new, comprehensive studies. No endemic genera fall to be recorded. Most of the several hundreds of taxonomic or biogeeographic papers from which this information was extracted suffer from poor or outdated taxonomy, such that up to half of all species are up for re-evaluation. Detailed morphological examination, but also provoked male production, especially in chydorids, are ways to improve identifications and should be stimulated. On the other hand, the inventory is certainly still incomplete with several tropical-subtropical taxa still to be expected in China. The extreme south and islands are among promising sites that remain to be explored, as well as extreme habitats all over the country. Molecular studies in China started around the beginning or the present decade, and should be multiplied.

[Physiological response of Neocaridina denticulate to the toxicity of Cu2+ and chlorpyrifos].

In order to study the physiological response to heavy metals and organic-phosphorus pesticide toxicity of aquatic organisms, Neocaridina denticulate was used as a test organism to investigate the impact of physiological indices of N. denticulate muscle tissues when they were exposed to Cu2+ and chlorpyrifos for 5 days respectively with the test methods of semi-static toxicity. The results showed that: when exposed to different concentrations of Cu2+ and chlorpyrifos solutions, the protein concentrations in muscle tissues were significantly lower with the extension of time to varying degrees. In the lower concentration groups of Cu2+ (0.086 mg x L(-1) and 0.172 mg-L-') and the higher concentration groups of chlorpyrifos (0. 006 0 [g-L-' and 0.012 0 µg x L(-1)), the total SOD activity showed inhibitory effect; the trend of the higher concentration group of Cu2+ (0.344 mg x L(-1) and 0.688 mg x L(-1)) showed " inhibition-promotion-inhibition", however, the lower concentration groups of chlorpyrifos (0.001 5 µg x L(-1) and 0.003 0 µg x L(-1)) showed the" inhibition-promotion" changes in trends; MDA contents changed similarly, and within a certain range of concentrations, MDA contents presented a gradually rising trend with increasing Cu2+ and chlorpyrifos concentration, which indicated that Cu2+ and chlorpyrifos accelerated lipid, peroxidation in muscle tissues of N. denticulate. In addition, AChE activity in Cu2+ and chlorpyrifos solutions showed inhibitory effect, and in the solutions with higher concentration of Cu2+ and chlorpyrifos, the activity was gradually decreased with the increase of concentration, indicating that Cu2+ and chlorpyrifoscs impacted the normal physiological functions of N. denticulate, and the higher the concentration, the greater the damage effect. Based on the analysis results, we confirmed that the total SOD, MDA and AChE played significant roles as physiological indicators in evaluating toxic effect of heavy metals and organic-phosphorus pesticide on N. denticulate.

Annotated Checklist of Chinese Cladocera (Crustacea: Branchiopoda). Part I. Haplopoda, Ctenopoda, Onychopoda and Anomopoda (families Daphniidae, Moinidae, Bosminidae, Ilyocryptidae).

Approximately 199 cladoceran species, 5 marine and 194 freshwater and continental saltwater species, live in China. Of these, 89 species are discussed in this paper. They belong to the 4 cladoceran orders, 10 families and 23 genera. There are 2 species in Leptodoridae; 6 species in 4 genera and 3 families in order Onychopoda; 18 species in 7 genera and 2 families in order Ctenopoda; and 63 species in 11 genera and 4 families in non-Radopoda Anomopoda. Five species might be endemic of China and three of Asia. Many records are suspect at the species level, and numerous taxonomic problems remain to be settled.

Planktonic rotifers in a subtropical shallow lake: succession, relationship to environmental factors, and use as bioindicators.

Changes in the density and species composition of planktonic rotifers as well as their relationship to several environmental variables were studied at Dadian Lake, a shallow subtropical lake, which was completely dredged and reconstructed. Samples were taken monthly (2006-2009) at five stations. The total rotifer abundance exponentially declined and reached a relatively stable stage in 2009. Polyarthra dolichoptera and Trichocerca pusilla dominated the rotifer community in most seasons. TN, TP, and CODMn went down at the beginning of the monitoring period, rebounded in the second winter, and then decreased and reached a stable state in 2009. CCA showed that the most significant variations were caused by fluctuations in temperature, COD(Mn), SRP, and NO2-N. The rotifer community experienced a two-stage succession and the difference of species between the stages was exhibited during warm seasons. GAMs indicated that the selected factors were responsible for 64.8% of the total rotifer abundance variance and 16.5~64.3% of the variances of individual species abundance. Most of the environmental parameters had effects on rotifer abundance that could only be described by complicated curves, characterised by unimodality and bimodality instead of linearity. Our study highlighted the temperature influence on rotifer species composition and total abundance in subtropical lakes.

[Dynamic of phytoplankton abundance and the relationship with environmental factors in Dianshan Lake, Shanghai].

During January 2004 to December 2006, the abundance of phytoplankton and environmental factors such as the water temperature, wind speed, transparency of water (SD), TN, TP, pH, and permanganate index were monitored monthly in Dianshan Lake. The water quality of Dianshan Lake was in the mid-eutrophication state. The correlation analysis between phytoplankton community and environmental factors were performed. It indicated that the phytoplankton abundance, cyanobacteria abundance in Dianshan Lake were positively correlated with temperature (r = 0.487, r = 0.497), pH (r = 0.415, r = 0.379) and permanganate index (r = 0.460, r = 0.436), and negatively correlated with SD (r = -0.382, r = -0.394). Chlorophyta abundance in Dianshan Lake was positively correlated with PO4(3-) -P (r = 0.466). There was also a significant positive correlation between phytoplankton abundance and cyanobacteria abundance (r = 0.970). According to (CCA) ordination analysis, temperature, DO, SD and PO4(3-) -P were main factors affecting dynamic characteristics of phytoplankton community. The meteorological and hydrological factors were more important than nutrition concentration related to the water bloom in Dianshan Lake.