An artifi cial oyster shell reef was deployed in Rongcheng Bay, East China. However, the effects of this reef on the surrounding macrobenthic communities were unknown. We compared sedimentary factors, macrobenthic biomass, abundance, and community composition and ecological indicators between the reef and non-reef areas over a one year period. The mean values for chlorophyll a(Chl a), total organic matter(TOM), total organic carbon(TOC), and total nitrogen(TN) content in surface sediments in the reef area were slightly higher than those in the non-reef area. The Chl a levels differed signifi cantly between the two areas, but the TOM, TOC, and TN were not signifi cantly different. The abundance of crustaceans was signifi cantly different between the two areas, but the abundance and biomass of polychaetes, echinoderms, mollusk did not differ signifi cantly. The permutational multivariate analysis of variance(PERMANOVA) revealed that the macrobenthic community differed signifi cantly through time and analysis of similarity multivariate analyses(ANOSIM) revealed that the macrobenthic community differed signifi cantly in some months. The ecological indicators revealed that the environmental quality of the reef area was slightly better than that of the non-reef area. Overall, our results suggest that the artifi cial oyster shell reef may change the macrobenthic community and the quality of the environment. Despite the lack of an effect in the short term, long-term monitoring is still needed to evaluate the effects of artifi cial oyster shell reefs on macrobenthic communities.
There is substantial individual variation in the growth rates of sea cucumber Apostichopus japonicus individuals. This necessitates additional work to grade the seed stock and lengthens the production period. We evaluated the infl uence of three culture methods(free-mixed, isolated-mixed, isolated-alone) on individual variation in growth and assessed the relationship between feeding, energy conversion efficiency, and individual growth variation in individually cultured sea cucumbers. Of the different culture methods, animals grew best when reared in the isolated-mixed treatment(i.e., size classes were held separately), though there was no difference in individual variation in growth between rearing treatment groups. The individual variation in growth was primarily attributed to genetic factors. The difference in food conversion efficiency caused by genetic differences among individuals was thought to be the origin of the variance. The level of individual growth variation may be altered by interactions among individuals and environmental heterogeneity. Our results suggest that, in addition to traditional seed grading, design of a new kind of substrate that changes the spatial distribution of sea cucumbers would effectively enhance growth and reduce individual variation in growth of sea cucumbers in culture.
Fatty acids(FAs) provide energy and also can be used to trace trophic relationships among organisms.Sea cucumber Apostichopus japonicus goes into a state of aestivation during warm summer months.We examined fatty acid profiles in aestivated and non-aestivated A.japonicus using multivariate analyses(PERMANOVA,MDS,ANOSIM,and SIMPER).The results indicate that the fatty acid profiles of aestivated and non-aestivated sea cucumbers differed significantly.The FAs that were produced by bacteria and brown kelp contributed the most to the differences in the fatty acid composition of aestivated and nonaestivated sea cucumbers.Aestivated sea cucumbers may synthesize FAs from heterotrophic bacteria during early aestivation,and long chain FAs such as eicosapentaenoic(EPA) and docosahexaenoic acid(DHA) that produced from intestinal degradation,are digested during deep aestivation.Specific changes in the fatty acid composition of A.japonicus during aestivation needs more detailed study in the future.
