遮浪湾浮游幼虫主要类别的形态

在对粤东遮浪湾浮游幼虫样品进行初步鉴定和分类的基础上,对其中主要类别的45个典型幼虫作简要的形态描述。湾中浮游幼虫分属12个动物门,30种类型,其中环节动物多毛类幼虫分属10个科。个别类型和形态的浮游幼虫在我国海区属首次报道。     

Sea water environment copper requirement of egg hatching and naupliar metamorphosis of Peaneus chinensis

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Salinity tolerance of northern Brazilian mangrove crab larvae, Ucides cordatus (Ocypodidae): Necessity for larval export?

The life cycle of the semiterrestrial mangrove crab Ucides cordatus includes pelagic larvae that are released into estuarine waters during the wet season and who may thus encounter potentially stressful low and variable salinity conditions. The effect of salinity on the survival of the zoea larvae, the number of zoeal stages and the duration of development from hatching to megalopa was experimentally studied by rearing larvae from the Caeté estuary, Northern Brazil, in seven salinity treatments (0, 5, 10, 15, 20, 25, and 30). For a better interpretation of the laboratory results, estuarine salinities were measured over five consecutive years during the species' reproductive season. The survival of the zoea larvae varied significantly with salinity, while the number of stages and the duration of their development remained constant. Development to megalopa took 20.77 ± 1.57 days and comprised five zoeal stages with ZI and ZII being euryhaline and later stages stenohaline. The newly hatched larvae stayed alive for up to 6 days in freshwater (average 4.32 ± 0.82 days), but did not moult to the second zoeal stage. ZII larvae first occurred from salinity 5 onwards and later zoeal stages at all tested salinities ≥10. However, the larvae only survived to megalopa at salinities ≥15, with highest numbers at salinity 30 (72%) and lowest at 15 (16%). Lethal salinities ≤10 occurred frequently in the estuary during the reproductive season. This suggests a need for larval export to offshore and thus more saline waters to allow for significant larval survival and maintenance of viable populations of this commercially important species. A regional rather than local approach for management is suggested due to the likelihood of long distance larval dispersal by offshore currents.     

中国对虾人工育苗中直接投喂去壳卤虫卵的饵料效果

为了有效地利用我国大量的低孵化率卤虫卵,我们自1989年—1992年,进行了去壳卤虫卵工厂化生产和在中国对虾育苗中直接投喂去壳卤虫卵的饵料效果的研究,应用结果表明:直接投喂去壳卤虫卵,对虾各期幼体均能正常变态进入仔虾期,其发育速度和密度与投喂卤虫无节幼虫的饵料效果基本相同。     

Developmental duration and morphology of the sea star asterias amurensis, in tongyeong, Korea

The process of embryogenesis and larval development of the asteroid sea star Asterias amurensis (Lütken) was observed, with special attention paid to morphological change and larval duration. In reproductive season, mature sea stars were collected under floating net cages, located in Tongyeong, southern Korea. The mature eggs are 138 μm in average diameter, semi-translucent and orange in color, sperms in good condition appear light cream to white-gray in color. Embryos develop through the holoblastic equal cleavage stage and a wrinkled blastula stage that lasts about 9 hours after fertilization. Gastrulae bearing an expanded archenteron hatch from the fertilization envelope 22 hours after fertilization. At the end of gastrulation, rudiments of the left and right coelom are formed. By day 2, larvae possess complete alimentary canal and begin to feed. At this stage, the larva is called early bipinnaria. In 6day-old larvae, the pre- and post- oral ciliated bands form complete circuits and the bipinnarial processes start to develop. By day 12, the lateral and anterior projection of the larval wall processes along the ciliated bands begins to thicken and curl, and the ciliated bands become more prominent. By day 32, early brachiolaria are presented with three pairs of brachiolar arms. Advanced brachiolaria with a well-developed brachiolar complex (three pairs of brachia and central adhesive disc) occur 6 weeks after fertilization. In the field, spawning of the sea star was observed in April to May, settlement form larvae and just settlements seem to occur from June to July, and early juveniles occur from August to September. Although we had not described the end of brachiolaria stage, it can be tentatively estimated that the duration of the pelagic stage of A. amurensis is 40 to 50 days.     

不同浓度的KCI对海湾扇贝眼点幼虫附着变态作用的研究

本文在有附着基的条件下进行KCI溶液对海湾扇贝眼点幼虫的附着变态研究，并观察春成活情况。结果表明：KCI对眼点幼虫的诱导效应随KCI浓度和作用时间的增大而增大，但过高则抑制眼点幼虫的附着变态,而成活率则随浓度增加和处理时间延长而降低，其中30mmol/L效果最好。并进行了小型生产试验，效果较好。     

Internal tidal bore warm fronts and settlement of invertebrates in central Chile

We studied the occurrence of large high frequency temperature fluctuations and their potential association with settlement of intertidal invertebrates during the spring/summer period 1999/2000 at Las Cruces, on the coast of central Chile. Our results showed the existence of internal tidal bores, characterized by sharp drops in water temperature at the surface and near the bottom, and subsequent temperature increases, which occurred with a semidiurnal periodicity. Measured currents support the hypothesis of alternating onshore and offshore movement of warm-water fronts. The frequency of the events varied through the summer and their amplitude seems to be modulated by onshore winds. The strongest events were observed when strong onshore winds occurred in late afternoon hours and the entire water column showed a semidiurnal temperature signal. Highest values of chlorophyll concentration in the intertidal zone and daily settlement of bivalves, gastropods and crustaceans were observed at times when conditions were favorable for occurrence of internal tidal bores. Results suggest that internal tidal bore warm fronts could play an important role in the transport of neustonic larval invertebrates and the delivery of phytoplankton to at least some intertidal sites along the coast of Chile.     

What can flatfish ontogenies tell us about pelagic and benthic lifestyles?

Eye migration, asymmetrical pigmentation, and a 90° rotation in posture are developmental changes that unify all flatfishes and facilitate a transition from a pelagic to a benthic existence. Settlement places the fish in new environmental conditions which may require different types and levels of performance for survival compared to those needed in the water column. Since structure and performance vary as a consequence of ontogeny, it is likely that natural selection has acted on the ontogeny of flatfishes differently from fishes that do not settle (pelagic fishes) to provide different survival skills by the time flatfishes settle. This paper provides examples of quantitative methods for comparing fish ontogenies in the context of three predictions: (1) different flatfish species undergo settlement at a common ontogenetic state; (2) they have a common set of skills at settlement that differ from those of pelagic species of the same ontogenetic state; and (3) skills or features that appear earlier in the ontogenetic program of flatfishes than in pelagic fishes suggest attributes that are important to survival in a benthic habitat. Preliminary comparisons suggest that flatfishes may have accelerated development of their mechanosensory system relative to pelagic species. Firm conclusions about ecologically important differences between the pelagic and benthic habitats derived from analyses of ontogenetic events will require more kinds of data from a broader selection of species.