The occurrences of harmful algal blooms (HABs), in terms of frequency and area in the Chinese coastal waters, have been increasing since 1980s and caused considerable economic losses. In the present study, we have analyzed spatial and seasonal characteristics of HAB events in the southern Yellow Sea and East China Sea along Chinese coast from 1933 to 2004. With a total 435 HAB records, the most frequent HAB occurrence area (FHA) is off the Yangtze River mouth and another two FHA areas are located south of the Yangtze River estuary along about isobaths of 30-60 m coastal water in the East China Sea.
Epinecidin-1 is an antimicrobial peptide and plays a vital role in protecting fish against pathogenic infection. As a mimic of a grouper epinecidin-1 peptide, it has tertiary structures that closely resemble those of pleurocidin found in the winter flounder (Pleuronectes americanus). The tissue-specific, lipopolysaccharide (LPS)-stimulation-specific, and poly(I):poly(C)-stimulation-specific expressions of the grouper (Epinephelus coioides) epinecidin-1 antimicrobial peptide were determined using a comparative reverse-transcription polymerase chain reaction. Results of the tissue distribution analysis revealed high levels of epinecidin-1 messenger RNA (mRNA) in the head kidneys, intestines, and skin. Expression of epinecidin-1 mRNA was dose-dependently stimulated by both LPS and poly(I):poly(C). Immunohistochemical analysis with the polyclonal antiserum of a grouper epinecidin-1 peptide (rabbit polyclonal antibody) showed that the peptide was localized with the epinecidin-1 antibody in the gills and intestines. Two synthetic peptides of the grouper epinecidin-1 peptide (g-ple 22-51 and g-ple 22-42) and one winter flounder pleurocidin as a control exhibited high antimicrobial activities against gram-negative or gram-positive bacteria. In addition, peptide treatment was effective in promoting a significant increase in fish survival after the injection of Vibrio vulnificus in tilapia (Oreochromis mossambicus) and grouper. These results are relevant to the design of prophylactic and therapeutic strategies to counter bacterial infections, especially for preventing or ameliorating immune defects in fish during bacterial infections.
Assimilation efficiency (AE) of metals from ingested food is critical for understanding trace metal accumulat~on and trophic transfer in aquatic animals. Most recent measurements of metal AEs have been on aquatic invertebrates, whereas relatively few studes have examined metal assimilation in fishes. In this study we determined the AEs of Cd, Cr and Znin 2 fishes (pelagic glassy Ambassis urotaenia, Ambassidae, and the intertidal mudskipper Penophthalmus cantonensis, Gobiidae) feeding on 2 zooplankton prey (brine shrimp k t e m i a larvae and copepods). Zooplankton were radiolabeled either by feeding on radiolabeled phytoplankton or by direct exposure to radiotracers in the dissolved phase. Fishes were then fed with radiolabeled zooplankton prey for < l h., and the retention of ingested metals in the fishes was followed for 2 d. The measured AEs of Cd, Cr and Zn were 14 to 33, 4 to 12, and 5 to 17% in glassy fish, and 10 to 26, 4 to 19, and 11 to 31 % in mudskipper, respectively. Routes of radiolabeling in copepod prey did not affect metal AEs in either mudskipper or glassy, whereas metal AEs differed by up to 10-fold in glassy fish feeding on Artemia larvae labeled from different routes. There was little difference m the gut passage time of metals for different food types and metals or between fishes. AE was not significantly related to metal gut passage time or metal distribution in the soft tissues of zooplankton prey, for each metal. However, AE in mudskippers was significantly correlated with metal distribution in the prey's soft tissues when all 3 metals were considered. Our study demonstrated that marine fishes can appreciably assimilate trace metals, and trophic transfer should be considered as a source for metal accumulation in fishes.
The Luzon Strait is a channel between the Philippine Sea and the South China Sea. This area is traditionally classified as an oligotrophic zone with low primary productivity. Even so, high concentrations of pigment were detected 100 km southwest of the Strait through analysis of historical Coastal Zone Color Scanner (CZCS) data that the Nimbus-7 satellite collected during the winters
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