The genetic diversity and differentiation of 6 mud crab Scylla serrata populations from southeastern China are investigated using allozyme electrophoresis. The mean number of alleles per locus population is 1.3±0.1; the percentage of polymorphic loci per population is 27.3; the observed heterozygosity ranges from (0.195±0.083) to (0.241±0.090) and the expected heterozygosity ranges from (0.105±0.043) to (0.131±0.047 ). The coefficient of gene differentiation among populations is low (Fst=0.032), indicating that only 3.2 % of the total genetic diversity comes from inter-population, while the remaining 96.8 % comes from intra-population differences. The genetic distance among populations is 0.000～0.008 (the average is 0.002). Gene flow among the populations is large (Nm= 7.56).Genetic structure is very similar among 6 Scylla serrata populations.

The distribution and abundance of viable resting eggs of copepod Acartia pacifica in Xiamen Bay, China, were determined in the laboratory by the presence of nauplii hatched from the sediments. Sediment cores to a depth of 30cm, sliced at 1.0cm intervals, showed that most viable resting eggs of A. pacifica occurred near the sediment surface (0-5cm), and the number of viable eggs sharply decreased with depth of the sediment, although resting eggs remained viable as deep as 23cm. 210Pb nalyses of the sediments indicated that the maximum age of viable eggs of A. pacifica was 20.5 years and the mean egg age was 4.3 years. The egg mortality of A. pacifica in the sediment was 0.1408 year 1, or 85.92% annual egg survival, calculated by regressing ln(egg density) on the age of the sediment. The horizontal distribution of viable resting eggs ranged from 2.27 103 to 3.85 105 m 2, with a mean value of 9.49 104 m2. Regressions between viable eggs of A. pacifica and all fine-fraction particle size classes (at 2 Am intervals) were not significant. The accumulation of viable resting eggs that can persist for an extended period of time provided evidence for the existence of an egg bank of A. pacifica in the seabed of Xiamen Bay.