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Retention efficiencies (RE) of scallop (Chlamys farreri), oyster (Crassostrea gigas) and mussel (Mytilus edulis) in a flow-through system were measured to understand the short-term response to various particle and organic matter concentrations.
By comparing the RE of C. farreri with that of C. gigas and M. edulis, we gained further knowledge on the feeding physiological characteristics of C. farreri and ascertained the possible cause of high summer mortalities of this species. The experimental feeding conditions included
natural differences in the abundance and composition of suspended seston, as well as conditions in which seston abundance
and composition were manipulated by adding natural silt or cultured microalgae. The results show that in natural sea water,
the minimum particle size for maximal retention in M. edulis, C. gigas and C. farreri was approximately 4, 6, and 8 μm, respectively; the RE of 2-μm (equivalent spherical diameter) particles was 17%, 19%, and
8%, respectively; and the relative standardized RE was 58%, 49%, and 18%, respectively. In C. gigas and M. edulis, the minimal particle size for maximal retention did not change with food quality (organic content). C. farreri was more sensitive to fluctuations in particle concentration and organic content. With particle concentration increase, the
minimal particle size for maximal retention in scallop shifted to large particles and the RE for 2-μm particle decreased from
8% in natural seawater to 1.6%–6% in silt-enriched groups. With organic content increase, the minimal particle size for maximal
retention shifted from 8 to 5 μm in natural seawater.Variation in RE of C. farreri with food conditions and the relationship between lower RE and smaller particle size may hamper C. farreri from food taking due to the decrease in the size distribution of phytoplankton in Sungo Bay. 相似文献
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Morphological comparison between a selected fast-growing strain and the common cultured strain of turbot Scophthalmus maximus 总被引：2，自引：0，他引：2
To evaluate the effect of genetic improvement of the turbot Scophthalmus maximus, we analyzed morphological differences between a fast-growing strain obtained by family selection and the common cultured strain, by principal component analysis, stepwise discriminant analysis, and t-tests. Although they clearly differed morphologically, plots of the principal components of the two strains partially overlapped. However, the difference between the strains was supported with very high precision by discriminant analysis. The t-tests revealed that 4 of the 13 morphological traits analyzed were highly significantly different (P<0.01), 4 traits also differed significantly (P<0.05), and the remainder did not differ significantly. The coefficients of difference of the 13 traits were all lower than the threshold value between subspecies (1.28). Together, the results indicate that a trend for segregation of characters from the common cultured strain have already appeared in the selected fast-growing strain but the degree of segregation have not risen to subspecies level. 相似文献
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Retention efficiencies (RE) of scallop (Chlamys farreri),oyster (Crassostrea gigas) and mussel (Mytilus edulis) in a flow-through system were measured to understand the short-term response to various particle and organic matter concentrations.By comparing the RE of C.farreri with that of C.gigas and M.edulis,we gained further knowledge on the feeding physiological characteristics of C.farreri and ascertained the possible cause of high summer mortalities of this species.The experimental feeding conditions in... 相似文献
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从患病和濒死的中国对虾(Penaeus chinensis)头胸部分离提纯出一种杆状病毒,同时经对病虾的鳃、胃和中肠组织进行超薄切片及电镜观察,亦在上述组织的细胞核内发现大小相同、形态一致的大量杆状病毒粒子.成簇的病毒粒子主要在核内装配,并导致细胞结构的病变.病毒粒子大小约为320～400nm×100～130nm,两端钝圆,中部膨大,有囊膜,分内外两后,核衣壳大小为250～300nm×70～100nm.细胞内未观察到有核型多角体或颗粒体类包涵体存在.根据病毒学分类原则,该病毒应属于杆状病毒属无包涵体杆状病毒亚群,即杆状病毒C亚群. 相似文献
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