Lu Shou

Effects of fish farming on phytoplankton community under the thermal stress caused by a power plant in a eutrophic, semi-enclosed bay: induce toxic dinoflagellate (Prorocentrum minimum) blooms in cold seasons.

Six cruises were conducted in a fish farm adjacent to the Ninghai Power Plant in Xiangshan Bay, East China Sea. Fish farming significantly increased NH4(+), DIP, and TOC concentrations, while it significantly decreased the DO level. These increase/decrease trends were more pronounced in warmer seasons. Although culture practices did not significantly increase phytoplankton density, it drastically enhanced dinoflagellate abundance and domination. Significant differences in species diversity and community composition between the cages and the control area were also observed. Temperature elevation caused by thermal discharge associated with eutrophication resulted in a dominant species shift from diatoms alone to dinoflagellates and diatoms. This is the first report of stress-induced toxic dinoflagellate (Prorocentrum minimum) blooms in winter and the winter-spring transition in this bay. Therefore, the effects of aquaculture activity and power plant construction in such a eutrophic, semi-enclosed bay require further attention.

Temporal and spatial variability of benthic macrofauna communities in the Yangtze River estuary and adjacent area

Four cruise surveys were carried out in summer, winter, spring, and autumn from 2006 to 2007 to evaluate the seasonal distribution of macrobenthos in the Yangtze River estuary and its adjacent waters. A total of 59 sites were sampled and divided into three areas (estuary, inshore, and offshore areas). In all, 335 taxa were collected with polychaetes and mollusks being the dominant groups. Two-way ANOVA revealed significant differences among the numbers of species, densities, and biomasses in the areas. However, several differences were found among seasons. SIMPER analysis showed that the dominant species of macrobenthos varied in different areas, and the inshore area was the most complex of the three. The abundance/biomass comparison (ABC) curve of macrobenthos in the inshore area showed apparent rises and falls, which are characteristic of disturbance to macrobenthos. Canonical correspondence analysis showed that echinoids were closely related to the presence of silicates and temperature, whereas polychaetes were closely related to depth and temperature.

Macrobenthic assemblages of the Changjiang River estuary (Yangtze River, China) and adjacent continental shelf relative to mild summer hypoxia

To assess the effects of hypoxia, macrobenthic communities along an estuarine gradient of the Changjiang estuary and adjacent continental shelf were analyzed. This revealed spatial variations in the communities and relationships with environmental variables during periods of reduced dissolved oxygen (DO) concentration in summer. Statistical analyses revealed significant differences in macrobenthic community composition among the three zones: estuarine zone (EZ), mildly hypoxic zone (MHZ) in the continental shelf, and normoxic zone (NZ) in the continental shelf (Global R =0.206, P =0.002). Pairwise tests showed that the macrobenthic community composition of the EZ was significantly different from the MHZ (pairwise test R =0.305, P =0.001) and the NZ (pairwise test R =0.259, P =0.001). There was no significant difference in macrobenthic communities between the MHZ and the NZ (pairwise test R =0.062, P =0.114). The taxa included small and typically opportunistic polychaetes, which made the greatest contribution to the dissimilarity between the zones. The effects of mild hypoxia on the macrobenthic communities are a result not only of reduced DO concentration but also of differences in environmental variables such as temperature, salinity, and nutrient concentrations caused by stratification.

The ecological distributions of N, P utilizing bacteria and heterotrophic bacteria in the moderate hypoxia zone of the Changjiang Estuary

The distributions of N utilizing bacteria (denitrifying bacteria and ammonifying bacteria), P utilizing bacteria (organic phosphobacteria and inorganic phosphobacteria) and heterotrophic bacteria in the Changjiang Estuary, and the roles of main environmental factors in distributing bacteria, are explored with observations from two cruises in June and August 2006. Comparisons between the two important periods of initial hypoxia phase (June) and developed hypoxia phase (August) show differences in both bacterial distributions and the associated main environmental factors. First, the primary group of ammonifying bacteria has larger magnitude with spatial maximum value in the hypoxic stations related to sediment in August. The phosphobacterial abundance and detection rates in August are much lower than those in June, but the denitrifying bacterial abundance becomes greater in August. However, the difference of heterotrophic bacterial abundance between June and August is not obvious. Second, main environmental factors influencing bacteria vary from initial hypoxia phase to developed hypoxia phase. Two parameters (salinity and NO3−) in surface water and five environmental parameters (pH, salinity, PO43−, NO3− and temperature) in bottom water and surface sediment play major roles in the bacterial abundance in June, while different parameter combinations (salinity and PO4−) in surface water and different parameter combinations (DO, DOC, NO3−, PO43− and pH) in bottom water and surface sediment play major roles in August. Moreover, the bottom bacteria distributions in area south of 31°N are related to the position of the Taiwan Warm Current in June. The bacterial abundance and distribution may respond to the environmental change in the hypoxia processes of initial phase and developed phase. During the hypoxia processes, the whole structure of bacterial functional groups probably turns to different states, causing the recycling of nutrient regeneration and aggravating hypoxia regionally.

Concentration and potential health risk of heavy metals in seafoods collected from Sanmen Bay and its adjacent areas, China

Commercial marine fish, crustacean, and mollusc samples were collected from Sanmen Bay and its adjacent areas to investigate the accumulation of heavy metals in various species of marine organisms and evaluate the potential health risk for local consumers. The results indicated significant variations in metal contents among species. The highest concentrations of studied metals were found in molluscs, followed by crustaceans and fish. The first metal group of arsenic (As), cadmium, copper, and zinc were associated by their relatively high concentrations in the tissues of marine organisms, whereas chromium, mercury, and lead were identified the other group with low concentrations. Human health risk evaluation indicated that the exposure doses of most elements for coastal people were safe, except for As, which scored a high total target hazard quotient and target cancer risk value. Potential health risk of heavy metal exposure from seafood consumption should not be ignored.

Seasonal distribution of macrobenthos and its relationship with environmental factors in Yellow Sea and East China Sea

Macrobenthos samples were collected from the Yellow and East China Seas in four seasons during 2011 to 2012. The seasonal distribution of macrobenthos and its relationship with environmental factors were analyzed. A total of 562 macrobenthic species were identified, with polychaetes and mollusks accounting for 67% of the total number of species. A similarity percentage (SIMPER) analysis showed that the dominant species were bivalve mollusks in the Yellow Sea and small-sized polychaetes in the East China Sea. A two-factor analysis of variance showed significant seasonal variations in species number, density and diversity index, and significant regional differences of biomass and density. Two-factor community similarity analysis also showed significant seasonal and regional differences in macrobenthic communities. Canonical correspondence analysis indicated that the main environmental factors affecting the macrobenthic communities were water depth, temperature, dissolved oxygen, and inorganic nitrogen. The results demonstrate significant regional differences and seasonal variations in macrobenthos in the two seas. Sediment properties and water mass characteristics are speculated to be the causes of regional differences.

Benthic macrofaunal communities along an estuarine gradient in the Jiaojiang River estuary, China

Benthic macrofaunal communities along an estuarine gradient of a macrotidal estuary of the Jiaojiang River, China were analyzed to reveal spatial variations in those communities and their relationships with environmental variables. Benthic macrofauna were collected from 15 sampling stations in May and October 2010. Polychaetes and Mollusks are the dominant taxonomic groups. The species richness, density and Shannon diversity index generally tended to increase as one moved away from shore toward the outer stations of the estuary. Cluster analysis and multidimensional scaling ordinations indicated the presence of three distinct zones of macrofaunal communities in the estuary. Multivariate analyses showed a strong relationship exists between the macrofaunal communities and the environmental parameters in the Jiaojiang River estuary. Aside from salinity, dissolved inorganic nitrogen and soluble reactive phosphate contents were also the major factor affecting the structure of the macrofaunal communities. The results demonstrated the important effects of nutrient-load on the distributional patterns of benthic macrofaunal communities in nutrient-rich estuaries.

DYNAMIC CHANGES IN PHYTOPLANKTON COMMUNITY STRUCTURE AFTER THERMAL SHOCK AND CHLORINATION IN A SUBTROPICAL BAY: AN EXPERIMENTAL STUDY

Natural phytoplankton collected from the Yueqing Bay was exposed to a series of heat shock temperatures and chlorine dosages in a laboratory for simulating its passage through coastal power plant cooling systems. A short-term thermal shock (30 min) had no appreciable effect on the microalgae community for temperature elevation of 4-12°C in all seasons. However, the adverse effects of chlorination on the microalgae were considerably more severe than those of a thermal shock in terms of dominant succession, species richness, diversity, evenness, and community composition. Moreover, chlorination strongly influenced the diversity indices throughout a 15-d culture period, indicating an evident lagging effect on the injured cells of entrained microalgae. The dominance of small phytoplankton species (r-strategists, e.g., Melosira moniliformis, Nitzschia longissima, and Skeletonema costatum) gradually increased during chlorine dosage range from 1.0 to 3.2 mg L^(-1). A typical chlorine dosage of 1-2 mg L^(-1) in cooling systems was found to influence the entrained subtropical phytoplankton community structure.

Ecological distribution of bacteria in the sediment of the laver culture area and cage culture area in Xiangshangang Bay

Microbiological investigation was performed to determine the mariculture impact on the ecological distribution of bacteria in the sediment of the laver culture area and cage culture area of Xiangshangang Bay in January and October,2006,and the results were compared with those in adjacent non-cultured area of cage and laver culture.Bacterial quantity presents a series of characters in sediment:Higher bacterial number was observed in Oct.than that in Jan.,and the horizontal distribution of bacterial quantity displayed that Cage culture area[average of(9.6×104±2.0×105) cfu/g]Reference site near cage[average of(1.5×104±2.4×104) cfu/g]Laver culture area[average of(4.3×103±1.6×103) cfu/g]and Reference site near laver culture[average of(4.7×103±3.0×103) cfu/g].109 strains of heterotrophic bacteria isolated from laver culture area mainly belonged to 17 genera,and Bacillus and Coryneforms were the dominant genera.95 strains isolated from reference site near laver culture mainly belonged to 18 genera,and Bacillus and Coryneforms were the dominant genera.136 strains isolated from cage culture area mainly belonged to 11 genera,and Bacillus,Coryneforms,Pseudomonas,Acinetobacter and Vibrio were the dominant genera.Bacteria in sediment under laver culture and reference site near laver culture were mostly common ones that appeared in marine sediment,and the microbial densities in these two areas were higher than that in cage culture area and reference site near cage.Because of long-term drainage of organic matters,cage culture sediments microbial density had reduced,its bacterial composition was similar to that in muddy sea areas,and the effect on bacterial community induced by culture has spread to its adjacent area.It is clear that there exist differences in the characters of bacterial ecological distribution in laver and cage culture areas,and bacterial quantitative distribution and community structures were closely related to self-pollution status of mariculture.