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121.
The Blenniidae family is characterised by small cryptic fish. Due to the small size of these specimens, the sampling is very difficult and information about the ecological role of these fishes is vague. However, mariculture adds reef encrusting organisms that attract blennies, which makes sampling easier. Furthermore, recognising species feeding is critical to understand biological communities. In this study, we evaluated the diet of blenny Hypleurochilus fissicornis in a mariculture, to clarify its influence on the benthic fauna and its interactions with the reef environment. We evaluated the seasonal variation (four seasons chosen by the abiotic variables) and the ontogenic changes (three classes defined by L50 of the species: juvenile, transition and adult) in the diet. Hydrozoans were the main prey, but H. fissicornis fed on a variety of other benthic organisms, exhibiting opportunistic habits. The diet of H. fissicornis was complemented by Amphipods in autumn, Ostracods in winter, and bivalves in summer. Juveniles fed more on Ostracods than the other classes, while the transition class fed mainly on Hydrozoans and a variety of rare items, and adults consumed almost exclusively Hydrozoans and some Cirripedia. Therefore, we conclude that H. fissicornis is an opportunistic feeder and may influence benthic organisms. The establishment of fouling organisms on the mariculture structures allows the use of this area by the blenny, since they promote its feeding base.  相似文献   
122.
以室内育苗池或玻璃缸养殖方式,研究了不同培育密度、换水量和倒池培育对珠母贝浮游幼虫生长发育和存活的影响。结果表明:当培育密度为0.8、1.2只/mL,直线铰合期时间分别为7.00、7.40d,日均生长为5.16、4.87μm,壳顶期时间分别为10.76d和10.77d,眼点期密度为0.58只·mL-1和0.60只·mL-1,差异不显著;日换水量分别为40%、60%、80%,直线铰合期时间、壳顶期时间、日均生长及眼点期密度差异不显著,日换水量40%能满足幼虫的生长和存活;壳顶初期进行倒池培育,能促进浮游幼虫的生长发育和提高其存活率。  相似文献   
123.
陆源碎屑与碳酸盐混积岩及其油气地质意义   总被引:4,自引:0,他引:4  
根据混积岩的分类命名、沉积环境和沉积模式等的研究现状及其在石油地质领域的研究进展,综合分析得出:有利 于混合沉积的沉积相主要是滨海相、滨浅湖相,其次是浅海陆棚、陆表海、三角洲相等;对其沉积环境的分析表明,滨海 相混积岩发育的控制因素是潮汐作用、相对比较强的水动力条件以及有利于低等生物发育的浅海环境,控制滨浅湖相混积 岩发育的因素是频繁的湖平面和气候的变化;因此认为深入探讨混积岩的沉积微相及其环境因素,对于完善和统一混积岩 独立的分类方案和命名体系是一有效途径。在此基础上,结合柴西北区古近系和新近系中深层湖相混积岩的研究实例,初 步提出了湖相和海相的混合沉积综合模式示意图;根据与混积岩相关的烃源岩和油气储层的研究资料认为,滨、浅海相和 滨、浅湖等海(湖)陆过渡地带的混合沉积,也可成为优质储层和烃源岩的勘探靶区。  相似文献   
124.
studies have compared oyster reefs with adjacent natural shallow-water habitats.Here the resident benthic macroinvertebrate communities in an artificial oyster(Crassostrea ariakensis) reef and in adjacent natural estuarine shallow-water habitats(salt marsh,intertidal mudflat,and subtidal soft bottom) in the Changjiang(Yangtze) River estuary were described.The mean total densities and biomass,Margalef’s species richness,Pielou’s evenness and Shannon-Weaver biodiversity indices of the resident benthic macroinvertebrate communities differed significantly among the habitats.Significantly higher densities and biomass of benthic macroinvertebrates occurred in the oyster reef compared with the other three habitats.Ordination plots showed a clear separation in benthic macroinvertebrate communities among the four habitat types.The results demonstrated that the artificial oyster reef supported distinct and unique benthic communities,playing an important role in the complex estuarine habitat by supplying prey resources and contributing to biodiversity.In addition,the results suggested that the oyster reef had been restored successfully.  相似文献   
125.
Temporal patterns of larval brooding and settlement were investigated in a flat oyster (Ostrea chilensis) population in Tasman Bay, central New Zealand. The proportion of the population brooding larvae and larval settlement rates were monitored over 26 months. A peak period of brooding activity began in late spring and continued through summer. Maximum rates of 17% and 23% of adult oysters brooding larvae occurred in November and December, and an estimated 55–78% of adult oysters incubated larvae over the entire summer breeding period. These proportions of brooders are higher than those previously reported for Tasman Bay. A very low level of brooding activity (1%) occurred during winter. Temporal trends in larval settlement closely tracked brooding patterns. Settlement was greatest between November and January, and there were very low rates in winter. The seasonal breeding pattern in the population was intermediate between northern and southern populations, confirming a latitudinal gradient of reproductive behaviour for O. chilensis in New Zealand. Results are useful in optimising the timing of substrate deployment in an enhancement programme for the oyster fishery.  相似文献   
126.
川东北元坝地区上二叠统长兴组优质储层形成机制   总被引:1,自引:1,他引:0  
川东北元坝气田为千亿储量的海相气田, 上二叠统长兴组礁滩相气藏具有埋藏深、高温、高压、高含硫化氢、气-水关系及工程地质条件复杂等特征。优质储层主要为礁滩相的白云岩, 具有物性好、非均质性强、含气性好的特点。研究表明, 台地边缘生物礁及台地边缘浅滩相控制了有利的储层岩石组合类型与分布, 是优质储层发育的基础; 白云石化作用和溶蚀作用改善和提高了储层岩石的孔隙度, 构造活动形成的多期裂缝提高了储层的渗流性能, 沉积-成岩-构造破裂等多因素的综合作用和合理配置是川东北元坝地区长兴组优质白云岩储层形成关键。   相似文献   
127.
渤海湾地区广泛分布的古海面标志物,为建立该地区的相对海面变化曲线提供了良好的基础。过去20年来该地区已相继建立了一些相对海面变化曲线,但在讨论影响古海面标志物高程的因素时,未将构造活动与水动型海面变化及均衡作用对高程的贡献量加以区分。文章以该地区7个点的古海面标志物及相关层位的高程测量与年代学测定结果,经与地区性预测海面变化曲线进行对比后,定量讨论了该地区海面变化(包括绝对海面变化与冰川、水均衡作用)与构造活动对古海面标志物高程的贡献;并以壳体的稳定同位素、地层记录与古地震研究资料讨论了牡蛎礁体在建礁过程中所记录的构造下沉。  相似文献   
128.
Two multi-year oxygen isotope (δ18O) records were obtained from archaeological Ostrea angasi shells, confirming the potential of this species to provide valuable environmental records for the late Holocene period in southeastern Australia. High-resolution δ18Oshell samples from the O. angasi clearly display a seasonal variability, offering insight into past climate conditions in a region where such information is presently limited.

The oxygen isotope record in O. angasi reflects a combined temperature–salinity signal. Observations of δ18Oshell data from modern specimens are used as a point of reference to assist in decoupling these two influences, with the two archaeological samples compared with the δ18Oshell profile of four modern O. angasi. Assuming similar paleo- δ18Owater values at the collection sites, data from these archaeological shells present a record of temperatures during the period of their growth that are consistently lower than modern day, with mean annual temperatures ~2°C cooler.  相似文献   

129.
The commercial fishery for snapper Chrysophrys auratus (Bloch and Schneider) in the Hauraki Gulf is one of New Zealand's principal marine fisheries. The snapper catch from this area declined by 22% in 1972, and by a further 4% in 1973, following 4 y of high catches by Danish seiners.

Some of the decline can be attributed to economic factors within the industry, and adverse winter weather. However, the 1972 decline in Danish seine catches is an acceleration of an existing trend. It probably results from heavy exploitation of an accumulated stock, and from movement of a few strong year classes past the age at which they have contributed most to the catch. The slight recovery in the 1973 Danish seine catch resulted only from increased effort; catch per day at sea continued to fall. An improvement in catch and catch per day is unlikely for some years at least.

Snapper catches by other methods (trawl, long line, and set net) also declined during 1972, but the available data on fishing effort do not allow a detailed analysis. The trawl catch in the gulf fell further in 1973 as fishing effort was diverted to other grounds, but the catch by lines and nets improved slightly.  相似文献   
130.
Detailed comparisons of the larvae of four species of New Zealand oyster (Saccostrea glomer‐ata, Crassostrea gigas, Ostrea lutaria, and a new species of Ostrea) and one Chilean oyster (Ostrea chilensis) showed that larvae of species other than O. lutaria and O. chilensis share certain features. One conspicuous feature is a distinct tract, termed here the posterior dorsal sulcus, which runs from the posterior margin of prodissoconch I to the valve margin of prodissoconch II; other characteristic features are an umbonate, inequivalve shell and a provinculum bearing distinct teeth. The larvae of O. lutaria and O. chilensis, in contrast, lack the posterior dorsal sulcus, are nonumbonate, and have nearly equal valves with an edentulous provinculum. These distinctive features, together with other adult features, suggest that the two species are more appropriately included in a separate genus. The name Tiostrea is proposed for the new genus. Certain supraspecific groupings within the Ostreinae need to be re‐examined in the light of breeding experiments.  相似文献   
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