Environmental and health effects associated with Harmful Algal Bloom and marine algal toxins in China

The frequency and scale of Harmful Algal Bloom (HAB) and marine algal toxin incidents have been increasing and spreading in the past two decades, causing damages to the marine environment and threatening human life through contaminated seafood. To better understand the effect of HAB and marine algal toxins on marine environment and human health in China, this paper overviews HAB occurrence and marine algal toxin incidents, as well as their environmental and health effects in this country. HAB has been increasing rapidly along the Chinese coast since the 1970s, and at least 512 documented HAB events have occurred from 1952 to 2002 in the Chinese mainland. It has been found that PSP and DSP toxins are distributed widely along both the northern and southern Chinese coasts. The HAB and marine algal toxin events during the 1990s in China were summarized, showing that the HAB and algal toxins resulted in great damages to local fisheries, marine culture, quality of marine environment, and human health. Therefore, to protect the coastal environment and human health, attention to HAB and marine algal toxins is urgently needed from the environmental and epidemiological view.

Effects of diatoms on reproduction and growth of marine copepods

Two hot spots in marine ecology, deleterious effects of diatoms and feeding selectivity of copepods, as well as new progress on these two issues achieved in the recent ten years, are reviewed. These two issues are considered correlated closely. Diatoms and their metabolites can induce deleterious effects on growth, reproduction and development of copepods, including increase of mortality and decrease of egg production, hatching and growth rates. Such negative effects, resulting from either chemical toxin or nutritional deficiency, can be conquered in natural environments by diverse feeding. It is therefore concluded that deleterious effects of diatoms observed in laboratory or during blooming period are only a special case that accommodation of feeding strategy of copepods is disabled. To understand their feeding strategy in natural environments is a prerequisite to explaining the mechanisms of deleterious effects caused by diatoms, and makes it possible to re-evaluate the energy flow in marine ecosystems.

Distribution pattern of marine flagellate and its controlling factors in the central and north part of the Huanghai Sea in early summer

A survey was carried out in the central and north part of the Huanghai Sea (34.5degrees similar to 37.0degreesN, 120.5degrees similar to124.0degreesE) during June 12 similar to 27, 2000. It was found that the abundance of marine flagellate ranged from 45 to 1278 cell/ml, 479 cell/ml in average. Flagellate was more abundant in the central part than in the north part of Huanghai Sea, and the abundance decreased with the increasing distance from the coast, showing a similar distribution pattern with isotherm. Vertically, high density of flagellate was always presented in the bottom of thermocline, and formed a dense accumulation in the central area of the Huanghai Sea Cold Water Mass. The effects of physical and biological factors on the distribution of marine flagellate in early summer were discussed. Water temperature (especially the existence of thermocline) rather than salinity showed significant effect on the distribution pattern of marine flagellate in the Huanghai Sea in early summer. When comparing the abundance of marine flagellate with that of other microorganisms, it revealed a comparatively stable relationship among these organhisms, with a ratio of heterotrophic bacteria: cyanobacteria: flagellate: dinoflagellate: ciliate being 10(5) 10(3):10(2):10(1):10(0).

Application of Neomysis awatschensis as a standard marine toxicity test organism in China

The small mysid crustacean Neomysis awatschensis was collected in the west coast of Jiaozhou Bay, Qingdao, China in 1992 and acclimated and cultured in laboratory conditions since then. Standard acute toxicity tests using 4-6 d juvenile mysids of this species were conducted and the results were compared with Mysidopsis bahia, a standard toxicity test organism used in the US in terms of their sensitivities to reference toxins, as well as their taxonomy, morphology and geographic distributions. Because of its wide distribution along the Chinese coast, similar sensitivity to pollutants as M. bahia, short life history, small size and the case of handling, this study intended to use N. awatschensis as one of the standard marine organisms for toxicity testing in China. The species were applied to acute toxicity evaluations of drilling fluid and its additives I organotin TPT and toxic algae, and to chronic ( life cycle) toxicity assays of organotin TPT and a toxic dinofalgellate Alexandrium tamarense, respectively. Using N, awatschensis as a standard toxicity testing organism in marine pollution assessment in China is suggested.

Study on impact of dinoflagellate Alexandrium tamarense on life activities of marine bivalves

The effects of a PSP producing dinoflagellate Alexandrium tamarense on marine bivalves at their several important life,stages: egg, D - shape larva, eyespot larva, juvenile and adult, were studied! The results show that the hitching survival, activity, filtration and! growth were adversely affected by the alga and the impact was significantly increased with the increase of algal density. The inhibitory effect on egg hatching was most significant, which the hatching rate was only 30% of the control when exposed to the alga at 100 cell/cm(3) after 36 h. Further experiments show that the algal culture, re-suspended cells and cell fragments had the inhibitory effect, while no such effect was from the cell-free medium, cell contents and standard STX. The results indicate that the alga could produce unknown toxins, rather than PSP, associated with the cell surface.