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11.
Altered Benthic Prey-Availability Due to Episodic Oxygen Deficiency Caused by Drifting Algal Mats 总被引：8，自引：0，他引：8
Abstract. Large quantities of drifting algal mats have become a common phenomenon on shallow sandy bottoms in the northern Baltic Sea. A decomposing algal mat rapidly induces hypoxic or anoxic conditions in the underlying sediment and interferes with the normal living-mode of the benthos, i.e., mobility, feeding, and predator-prey relationships. Field surveys have shown that bivalves, such as Macoma balthica , avoid the unfavourable anoxic conditions by emerging at the sediment surface. Due to low reburrowing rates these bivalves are exposed to epibenthic predators once the drift algae disperse. A series of aquarium experiments were conducted to test for differences in the survival of M. balthica when exposed to continuous predation without prior stress and short-term predation after hypoxic stress induced by algae (= 20% 02-saturation). Sublethally stressed adult M. balthica , that normally are outside the size-range of the isopod predator Saduria entomon , became significantly more susceptible to predation when lying exposed at the sediment surface. The same effects were found with two other predators, the brown-shrimp Crangon crungon and the flounder Platichthysflesus . Drift algal mats induced an escape-reaction in the infauna more rapidly than mere hypoxia. This response is affected by temperature. which further underlines the importance of drift algae influencing prey availability. This paper discusses the role of the drift algae as a regulating factor for the infauna and demonstrates the importance of external structuring factors, such as hypoxic stress and algal mats, on predator-prey interactions. 相似文献
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首次对湖北梁子湖水系污染程度不同(中营养型、中富营养型、富营养型)的4个湖泊的底栖动物群落结构和物种多样性进行了周年研究，结果表明，底栖动物种类数、物种多样性与湖泊受污染程度呈负相关系，密度与污染程度大体上呈正相关．还讨论了底栖动物环境指示种生态特性，研究表明中国长足摇蚊的密度与水体营养水平呈正相关，软体动物种类数与湖泊污染程度呈负相关．通过对软体动物、寡毛类及摇蚊类密度和生物量在不同湖泊之间的差异的分析，表明湖泊水体污染导致了底栖动物多样性明显降低． 相似文献
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This paper describes the two-phase study of the environmental impact of the SwePol Link submarine electrical energy transfer system between Sweden and Poland. During the first phase (1997–1998), the potential effects of proposed technical solutions for the transmission line and different routes across the Baltic Sea were analysed. During the second phase (1999–2000), studies on environmental and background conditions before cable installation (1999) and studies on the environmental effects after cable system installation (2000) were undertaken. During this phase, underwater TV and video inspection of the bottom, observations of the bottom habitats by scuba-divers, sampling and laboratory analysis of macrozoobenthos and measurements of the earth's magnetic field were conducted.Underwater observations along the cable route indicated that one year after the cable had been laid no mechanical disturbances on the dynamic sandy bottom were visible. Studies of the bottom macrofauna indicated that there had been no significant changes in zoobenthos species composition, abundance or biomass which could have been clearly related to cable installation. Changes in the components of the magnetic field, although significant in the vicinity of the cable itself, did not exceed natural variability at a distance of 20 m. 相似文献
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Biodiversity, abundance and taxonomic composition of shallow-water zoobenthos were studied in the W?oc?awek Dam Reservoir (the lower Vistula River, central Poland). The following habitats located near the shore were studied: (1) sandy bottom in the flooded part of the reservoir; (2) sandy bottom close to the main riverine flow in the reservoir and (3) organic-rich bottom covered by a thick layer of plant remnants in a shallow, isolated cove. In each habitat we investigated two sites (ca. 0.5 and 1 m depth). Also examined was the bottom of a phytolittoral site (sandy bottom, with elodeids and nympheids, 1 m depth), located in the flooded zone. In general, the bottom fauna was highly diverse and abundant in these habitats. The highest biodiversity (38 taxa, Shannon-Wiener index=4.3) was found on the bottom rich in organic matter. However, the zoobenthos abundance in this habitat was comparatively low, probably due to periodical oxygen deficiencies. The highest density of bottom fauna (>30,000 individuals per m2), accompanied by its high biodiversity, occurred at the phytolittoral site. The benthic community of the organic-rich sediments was the most distinct, with many taxa occurring exclusively in this area. The composition of the bottom fauna, from the two sandy habitats and phytolittoral, also differed from one another. The differences in taxonomic composition between the shallower and deeper sites were less pronounced. Lower densities at the shallower sandy sites and a very high variability of taxonomic composition among particular samples from these sites indicated lower stability of their environmental conditions. These were certainly due to water level fluctuations and/or destructive wave action. On the other hand, no such differences were found between the sites of various depths from the organic-rich sediments, showing that this substratum provided better protection against adverse hydrodynamical factors. 相似文献
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江苏省水库底栖动物调查及其综合评价 总被引：11，自引：0，他引：11
于1998年5月-1999年5月对江苏省48座大中型水库底栖动物进行了调查．鉴定的底栖动物计75属种，优势种类为尾鳃蚓属（Branichiura）、水丝蚓属(Limnodrilus）、管水蚓属（Aulodrilus)、长足摇蚊属（Pelopia)、隐摇蚊（Cryptochironomus）等5属．底栖动物密度为288．4ind．／m^2，变动范围43．2-928．2ind．／m^2；生物量为8．753g／m^2，变动范围0．235—61．884g／m^2．北部、中部、南部水库各类底栖动物的季节变化呈现较大的差异．用Goodnight ＆ Whitley生物指数和Wright寡毛类密度法评价水库水质，除少数水库有轻度污染外，水质状况总体良好．用能量估算法估算水库底栖动物的平均渔产潜力为5．8kg/hm^2。 相似文献
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Abstract. seasonal sampling of three stations in Gulbahce Bay Aegean Sea for the zoobenthic organisms associated with a Zostera marina bed was carried out during 1993–94. Temperature, salinity and oxygen were recorded each sampling period. A total of 7 taxonomic groups were determined: Polychaeta was the dominant group comprising 77 % of the total taxa and individuals, followed by Crustacea, Bivalvia and other groups such as Nemertea. Sipuncula, Turbellaria and Phoronida. Of the 108 taxa encountered, the polychaetes Notomastus latericeus and Caulleriella alata accounted for 49 % of the total populations. The species abundance did not show major changes among seasons, with highest values in fall 982 indiv. ·m-2 and lowest in spring 754 indiv. ·m-2 . Diversity and evenness of the samples were relatively high and fairly constant, and were affected by the dominance levels of the species. 相似文献