The chronic effects of oil pollution on marine phytoplankton in a subtropical bay, China.

To evaluate the effects of crude oil water accommodated fraction (WAF) on marine phytoplankton community, natural phytoplankton collected seasonally from the Yueqing bay were exposed to eight groups of crude oil WAF for 15 days under laboratory conditions. Chlorophyll a and cell density were measured, and species of phytoplankton were identified every 24 h to reflect the change of phytoplankton community. The results showed that (1) High concentrations (≥ 2.28 mg l(-1)) of oil pollution would greatly restrain phytoplankton growth (p<0.001), decrease chlorophyll a content and cell density, whereas low concentrations (≤ 1.21 mg l(-1)) did not restrain its growth but rather promoted the phytoplankton growth. (2) The biodiversity, evenness, and species number of phytoplankton were all significantly influenced by crude oil WAF in all seasons (p<0.001). (3) The dominant species changes were different under different pollutant concentrations in different seasons. Different species had different tolerances to the oil pollution, thus leading to abnormal succession.

[Spatiotemporal distribution of macrobenthic communities and its relationships with environmental factors in Sanmen Bay].

In November 2006 and in January, April, and August 2007, an investigation on the macrobenthic communities was conducted at 18 stations in Sanmen Bay to study the relationships between the macrobenthic communities and environmental factors. A total of 124 taxa were collected, including 44 species of Polychaeta, 34 species of Crustacea, 22 species of Mollusca, 11 species of Echinodermata, and 13 species of others. The species of Polychaeta and Mollusca accounted for 62.9% of the total, which constituted the main population of the communities. Aglaophamus dibranchis, Capitella capitata, and Sternaspis scutata were the dominant species in spring, Sternaspis scutata, Aglaophamus dibranchis, and Spionidae spp. were the dominant species in summer, S. scutata, C. capitata, A. dibranchis and Virgularia gustaviana were the dominant species in autumn, and A. dibranchis, S. scutata, C. capitata, and Spionidae spp. were the dominant species in winter. There was a significant difference in the average biomass and average density of the macrobenthic communities between different seasons. The annual average biomass was 17.36 g x m(-2) and the annual average density was 72 ind x m(-1). The diversity indices of the macrobenthic communities also differed significantly between different seasons. The seasonal average Shannon diversity index was from 1.53 to 1.89, seasonal average Margalef species richness index was from 2. 25 to 2. 96, and seasonal average Pielou evenness index was from 0.83 to 0.94. Canonical correspondence analysis showed that the sea water temperature, salinity, and dissolved inorganic nitrogen, and the organic matter, total nitrogen, and total phosphorus in surface sediment were the main environmental factors affecting the macrobenthic communities. Environmental variables could better explain the changes of main macrobenthic species.

[Niche of macrozoobenthos in intertidal zone of Jiaojiang Estuary].

The niche width and niche overlap of macrozoobenthos dominant species in the intertidal zone of Jiaojiang Estuary in October 2007 were analyzed based on niche theory, and the effects of natural factors (salinity, water temperature, sediment temperature, beach width, and sediment grain size) and environmental factors (contents of oils and heavy metals) on the environmental heterogeneity as well as the relationships between selected environmental factors and quantitative distribution of various groups of macrozoobenthos were studied by using canonical correspondence analysis method. The macrozoobenthos dominant species in study area were classified into four groups, i. e., burrowing surface predator, surface grazer, subsurface filter feeder, and subsurface swallow feeder, based on their feeding types. There were great differences in the niche widths among the groups, with the maximum of 0.428 and the minimum of 0.168, which suggested that different groups had different adaptive capacity to the environmental factors. At the level of niche overlap value higher than 0.6, Macrophthalmus japonicas and M. definitus of Group 1, Lunatica gilva, Bullacta exarata, Decorifera insignis, Assiminea brevicula and Cerithidae ornate of Group 2, and Moerella iridescens, Glauconome chinensis and Potamocorbula laevis of Group 3 had a biologically significant niche overlap, indicating their similar behavior in utilizing natural feeding resources.

[Seasonal distribution of macrozoobenthos and its relations to environmental factors in Oujiang River estuary sea area].

To evaluate the seasonal distribution of macrozoobenthos and its relations to environmental factors in Oujiang River estuary and adjacent waters, two cruise surveys were conducted in May 2006 (spring) and January 2007 (winter). A total of 65 species were collected, among which, polychaeta and mollusk were the dominant groups, Capitella capitata and Nassarius succinctus were the dominant species in spring and winter, respectively. The species number of macrozoobenthos was more in adjacent sea area than in estuary, and more in spring than in winter. The average biomass and density in the two seasons were 19.66 g x m(-2) and 131 ind x m(-2), respectively. There was a significant difference in the macrozoobenthos density between the two seasons, while less difference was observed in the biomass. The Shannon-Weiner index had significant difference between the two seasons, while Pielou eveness index, Margalef abundance index, and Simpsom dominance index had not. Water temperature and phytoplankton were the key factors affecting the macrozoobenthic taxa in spring, and water total organic carbon and dissolve oxygen were the key affecting factors in winter.

[Thermal tolerance of some marine copepods].

By using experimental ecological methods, the 24 hours semi-lethal temperature (24 h LT50) of typical copepods living in the coastal area of East China Sea was determined to elucidate the effects of thermal discharge from power station on the coastal ecosystem. The results indicated that different copepods at same natural acclimated temperature and specific copepod at different initial acclimated temperature had different thermal tolerance capability. The 24h LT50 of Calanus sinicus and Sinocalanus tenellus at natural acclimated temperature 13.5 degrees C was 26.9 degrees C and 25.4 degrees C, of Acartiella sinensis and Corycaeus affinis at natural acclimated temperature 14.2 degrees C was 26.7 degrees C and 30.5 degrees C, and of Centropages dorsispinatus, Paracalanus crassirostris, Acartia spinicauda and Euterpina acutifrons at natural acclimated temperature 28.0 degrees C was 34.0 degrees C, 34.3 degrees C, 35.7 degrees C and 36.0 degrees C, respectively. The 24h LT50 of S. tenellus at natural acclimated temperature 13.5 degrees C and 23.5 degrees C was 25.4 degrees C and 33.0 degrees C, respectively.

[Effects of residual heat and chlorine in cooling water from coastal power plant on Calanus sinicus].

According to the practical operation of coastal power plant cooling system, a simulation study was conducted on the effects of residual heat and chlorine in the cooling water on Calanus sinicus. The results showed that the thermal tolerance of C. sinicus to the cooling water was decreased with increasing exposure duration but increased with increasing acclimation temperature. When the acclimation temperature was 16 degrees C-27 degrees C, the lethal temperature of C. sinicus under thermal shock for 15, 30 and 45 min was 29.9 degrees C-31.7 degrees C, 29.4 degrees C-31.0 degrees C and 28.9 degrees C-30.3 degrees C, and that of C. sinicus continually exposed to increasing temperature for 24 and 48 h was 26.9 degrees C-28.5 degrees C and 26.4 degrees C-28.0 degrees C, respectively. When the acclimation temperature increased to a certain degree, the thermal tolerance of C. sinicus maintained at a stable level. The toxicity of residual chlorine on C. sinicus enhanced with increasing acclimation temperature, temperature increment, and exposure duration.