共查询到20条相似文献，搜索用时 187 毫秒
1.
The number of immature stages and the seasonal patterns of development are basic life history features of a stream dwelling species and knowledge about these important components are essential for understanding its adaptations to its dynamic environment. The life cycle of Agapetus fuscipes (Trichoptera, Glossosomatidae), one of the dominant scrapers in the upper and middle reaches of the Breitenbach, a first-order upland stream in central Germany, was analysed. The pronotum length and the relationship between pronotum length, larval biomass and case length showed seven distinct larval instars, contrary to earlier findings from the Breitenbach. In addition to a few trichopteran species from other functional feeding groups, A. fuscipes is the only scraping caddis fly reported to have more than five larval instars. The moult increments of pronotum length and larval biomass were distinctly lower than in glossosomatid species with five larval instars. A. fuscipes is clearly univoltine in the Breitenbach. First-instar larvae were found from July to the beginning of December, and second-instar larvae from July to January. At the beginning of December the population consisted of the instars I to V, and development did not cease during winter. The sixth-instar larvae occurred mostly in January, and the seventh-instar larvae were never present before January. The prepupae and pupae occurred in April. The last pupae were found at the beginning of September, although most of the emergence took place in June and July. At least five different immature stages with different ecological demands were present at any time throughout the year. The ecological advantage having two additional larval instars compared to other glossosomatid species may be to compensate for the high rate of mouthpart wear that occurs while the larvae feed on the rough Bunter Sandstone substratum. A further advantage may be to spread the risk of high mortality under unfavourable environmental conditions. 相似文献
2.
《Marine pollution bulletin》2014,80(1-2):39-46
The tolerance and physiological responses of the larvae of two congeneric gastropods, the intertidal Nassarius festivus and subtidal Nassarius conoidalis, to the combined effects of ocean acidification (pCO2 at 380, 950, 1250 ppm), temperature (15, 30 °C) and salinity (10, 30 psu) were compared. Results of three-way ANOVA on cumulative mortality after 72-h exposure showed significant interactive effects in which mortality increased with pCO2 and temperature, but reduced at higher salinity for both species, with higher mortality being obtained for N. conoidalis. Similarly, respiration rate of the larvae increased with temperature and pCO2 level for both species, with a larger percentage increase for N. conoidalis. Larval swimming speed increased with temperature and salinity for both species whereas higher pCO2 reduced swimming speed in N. conoidalis but not N. festivus. The present findings indicated that subtidal congeneric species are more sensitive than their intertidal counterparts to the combined effects of these stressors. 相似文献
3.
Eric C. Merten Zachary R. Snobl Todd A. Wellnitz 《Aquatic Sciences - Research Across Boundaries》2014,76(2):165-172
Understanding the factors controlling insect emergence from streams has applications to ecological theory regarding cross-boundary flux, along with practical value for monitoring stream function after restoration projects. We hypothesized that stream microhabitat would have effects on emergence that were independent of those mediated by the local stock of benthic macroinvertebrates. We set 50 emergence traps in a third-order stream in northern Minnesota, USA, during two study periods and used structural equation modeling to examine direct and indirect effects of benthic stock and microhabitat features on emergence. Emergence by biomass showed direct positive relationships to substrates of fines and detritus in the first sampling period, and to shallow depth and wood area in the second period. Emergence by abundance had direct positive relationships with benthic stock, CPOM, and fewer macrophytes in the first period, and with benthic stock and periphyton in the second period. Fine substrates may act to concentrate burrowing larvae, whereas CPOM and particularly wood may intercept drifting pre-emergent insects and provide exiting surfaces. Shallow depths may reduce the extent to which resident insects drift downstream (and leave the sample area) while emerging. Periphyton may be an indicator for patches with greater illumination, which itself attracts emergers. Our results suggest emergence is sensitive to environmental conditions at the microhabitat scale, and that stream restoration activities should consider habitat for emerging insects when designing projects. 相似文献
4.
J.T. Enright 《Marine pollution bulletin》1977,8(7):158-161
The use of coastal oceanic waters in the cooling systems of power plants leads to the destruction of large numbers of planktonic larvae of nearshore fish and invertebrates. As a first-order approach toward assessing the maximum probable impact of such larval mortality upon the adult populations, one can assume that recruitment to local populations is due to larvae from distant sources, which have a recruitment success independent of adult density; and that adult mortality is density-independent. These worst-possible-case assumptions lead to the interpretation that impact on adult populations could be adequately evaluated by measuring—or predicting—the power-plant imposed reductions in larval density in those near-shore waters from which recruitment occurs. 相似文献
5.
Granmo A Ekelund R Sneli JA Berggren M Svavarsson J 《Marine pollution bulletin》2002,44(10):1142-1148
To assess the risk of antifoulant use to the commercially important cod (Gadus morhua L.), fertilised cod eggs were exposed to triazine, copper and TBTO singly or combined in laboratory tests with running seawater. At the highest tested concentrations (11.5 microg Cu l(-1); 5 microg TBTO l(-1)) larval mortality was increased. The highest concentration of triazine (40 microg l(-1)) did not cause any significant mortality. Fertilised eggs that had been exposed to all the three chemicals singly for five days showed a higher buoyancy than the controls. No synergistic or antagonistic effects were indicated. Embryos/larvae exposed to 0.004-0.8 microg TBTO l(-1) did not show any changed respiration compared to the controls after hatching. It is concluded that existing known field concentrations of the three antifoulants are hardly expected to cause detectable effects on fish embryonic/larval development. 相似文献
6.
This study examined the interactive effects of copper and elevated temperature and subsequent depuration on Platygyra acuta coral larvae. Larval mortality and motility were significantly affected by copper alone (70% and 100% inhibition respectively). Their respective lethal/inhibitory concentration (LC50/IC50) were 10–130% and 86–193% higher than those reported for other larvae. Temperature (ambient, 27 °C and elevated, 30 °C) alone and the combination of temperature and copper did not significantly affect both endpoints. This study provides the first quantitative data on depuration effect on resumption of larval motility after copper exposure, although no sign of larval recovery was observed. These findings suggest that the effects of copper pollution outweigh the thermal tolerance of coral larvae. High LC50 and IC50 recorded may be unique for corals from marginal reefs like Hong Kong which have already been exposed to high levels of copper pollution. 相似文献
7.
Boundary layers between different environmental compartments represent critical interfaces for biological, chemical and physical processes. The sea-surface microlayer (uppermost 1-1000 microm layer) forms the boundary layer interface between the atmosphere and ocean. Environmental processes are controlled by the SML, and it is known to play a key role in the global distribution of anthropogenic pollutants. Due to its unique chemical composition, the upper organic film of the SML represents both a sink and a source for a range of pollutants including chlorinated hydrocarbons, organotin compounds, petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAH) and heavy metals. These pollutants can be enriched in the SML by up to 500 times relative to concentrations occurring in the underlying bulk water column. The SML is also a unique ecosystem, serving as an important habitat for fish eggs and larvae. Concentration ranges and enrichment factors of pollutants in the SML in different areas of the world's oceans have been critically reviewed, together with available toxicity data for marine biota found within the SML. Overall, the SML is highly contaminated in many urban and industrialized areas of the world, resulting in severe ecotoxicological impacts. Such impacts may lead to drastic effects on the marine food web and to fishery recruitment in coastal waters. Studies of the toxicity of fish eggs and larvae exposed to the SML contaminants have shown that the SML in polluted areas leads to significantly higher rates of mortality and abnormality of fish embryos and larvae. 相似文献
8.
Krystyna Czyżewska 《Marine pollution bulletin》1976,7(6):108-112
The effect of a mixture of anionic (ethoxylate) and non-ionic (alkylate) detergents on developmental stages of the crab Rhithropanopeus from final embryogenesis to the Megalopa larval stage has been studied. Larval resistance increases with age. Larvae still in the eggshells are only slightly sensitive because of the thick and impermeable chorion. Low concentrations of detergents exert a favourable effect, causing a decrease in larval mortality, but during moults there is an increasing mortality and a lengthening of the developmental period of the larvae. The mixture of detergents is more toxic than single detergents. 相似文献
9.
Laboratory reared veliger larvae of the common mussel Mytilus edulis were grown for 15 days in filtered seawater containing 10 μg l?1, 1 μg l?1 and 0.1 μg l?1 tributyltin oxide (TBTO), the biocide in recent antifouling paint formulations. No larvae survived longer than 5 days in 10 μg l?1 TBTO or 10 days in 1 μg l?1 TBTO. Approximately half the larvae subjected to 0.1 μg l?1 TBTO were dead by day 15 (approximate 15 day LC50 = 0.1 μg l?1 TBTO) and most of the surviving larvae were moribund and had grown significantly more slowly than controls. It is noted that current recorded levels of TBT at several UK estuarine sites are higher than 0.1 μg l?1 and there has therefore probably been a high mortality of mussel larvae at such sites. The results are discussed in relation to the reported short-term toxicity of organotins to other marine organisms and the value of carrying out longer-term tests at low levels of TBT is pointed out. 相似文献
10.
11.
2003年春、夏、秋季对黄河三角洲7座平原型水库进行了4次调查,发现:1)由摇蚊科幼虫和水蚯蚓构成的大型底栖动物,体内磷含量随底泥沉积磷的增加而增加(P<0．000),底柄动物对沉积磷的积累系数亦随沉积磷含量的增加而增加(p<0．000);2)4、5月份摇蚊幼虫在底栖动物体所占不同比例(20％-100％),没有显示与底柄动物体内磷含量任何关系;3)底栖动物含磷量与水层总磷无显著相关关系;4)底柄动物生物量与沉积总磷仅4月份有相关(p<0．10),其中摇蚊幼虫生物量与沉积磷量相关显著(P<0．05),总体上,水库底柄动物最高生物量随沉积磷增加而增加;5)底栖动物生物量与水层总磷无相关关系,但去掉底层鱼产量高的水库后,8月份二者有显著相关关系(p<0．03),且总体底栖动物最高生物量也随水层总磷增加而增加．认为:1)由摇蚊科幼虫和水蚯蚓构成的大型底柄动物对磷的积累以及摇蚊幼虫的生物量均与水体磷负荷有密切关系;2)摇蚊幼虫和水蚯蚓含磷量(干重)差异不明显;3)以摇蚊幼虫为主的底栖动物对磷的积累主要来自沉积磷的影响,受季节的影响相对较弱;4)底栖动物生物量主要受水层总磷的控制,也受鱼类摄食以及摇蚊幼虫个体羽化时间不一致的影响． 相似文献
12.
Renée Katrin Bechmann Bodil Katrine Larsen Ingrid Christina Taban Per Møller 《Marine pollution bulletin》2010,60(11):2087-2098
Adult shrimps (Pandalus borealis) and their embryos were exposed to an oil-water dispersion (OWD) at concentrations of 0.015, 0.06 and 0.25 mg/L using a continuous flow system. Lysosomal membrane stability was analysed in haemocytes using the neutral red retention assay and an alkaline unwinding assay was used to measure DNA damage in hepatopancreas tissue. Exposure to oil induced concentration and time dependent biomarker responses in adult shrimps together with the accumulation of PAH in their tissues. Oil exposure of shrimp embryos caused increased mortality in the resultant larvae, even if the larvae were kept in clean water after hatching. There were minor differences observed in larval stage development times in the first part of the experiments. The fatty acid composition of embryos exposed to oil was different to that of non-exposed larvae. PAH tissue concentration and biomarker responses correlated to the reduced survival of the shrimp larvae. 相似文献
13.
Coral cover and partial mortality on anthropogenically impacted coral reefs at Eilat, northern Red Sea 总被引：1，自引：0，他引：1
A photographic analysis was conducted at five shallow reef sites (5-6 m) at Eilat (northern Red Sea) to study changes in live coral cover during a 2-year period. Logit regression analysis showed that levels of total oxidized nitrogen (TON; NO(2)+NO(3)) and the presence of SCUBA divers were significant explicative variables of coral partial mortality, while sedimentation rate was not significant. Sites exposed to mean TON levels above 0.4 microM TON showed significantly lower live stony coral cover and abundance per m(2), and higher partial mortality of coral colonies than sites exposed to lower TON. These findings may be useful in establishing limits for TON levels at Eilat, but must be interpreted with caution due to the complexity of nutrient dynamics in coral reefs, the uncertainty of the effects of nutrients on coral physiological processes, and the possibility of interactions among multiple coral stressors. 相似文献
14.
Rh. germanica is a European species that, due to human impacts, has progressively disappeared from its original territories and is now considered rare. In SwitzerlandRh. germanica has disappeared from the Aare, Broye and Kleine Emme rivers and is actually found in a limited reach of the River Rhine and some of its tributaries (Limmat, Sihl, Thur and Töss rivers).Rh. germanica is a univoltine species, hatching probably in summer. The emergence occurs from February to the beginning of April. It takes place on the water surface. Laboratory observations have shown that the subimaginal stage lasts four days.Rh. germanica occurs on different substrate types, ranging from stones and cobbles to pebbles and gravel. The larvae are more abundant in zones of erosion with coarse and porous sediments than in depositional zones with fine sediments and silts. They are most abundant in riffles with water velocities from 20 to 150 cm/sec. The species tolerates moderately organic-polluted waters.The particular strategy concerning growth and emergence ofRh. germanica is also discussed. 相似文献
15.
Judith M. Capuzzo Joel C. Goldman John A. Davidson Sarah A. Lawrence 《Marine pollution bulletin》1977,8(7):161-163
The effects of free chlorine and chloramine on stage I lobster larvae and juvenile killifish were investigated in continuous flow bioassay units. In comparing mortality and changes in standard respiration rates during and after exposure to either chlorine form, significant respiratory stress was observed with exposure to sublethal levels. Sublethal responses to free and combined chlorine should be considered when establishing regulations for chlorine residuals in cooling waters. 相似文献
16.
武汉南湖三种摇蚊幼虫生物学特性及其种群变动的研究 总被引：5，自引：3，他引：2
通过周年15次野外定量取样结合室内培养,对武汉南湖中的中国长足摇蚊Tanypus chinensis Wang、六附器德永摇蚊Tokunagayusurika sezpapilosus(Yan ＆ Ye)和半褶皱摇蚊Chironomus plumosus f.semireduclus Lenz的种群动态和生物学特性(食性、筑巢、羽化期、世代数、越冬幼虫等)进行了研究,并得出半褶皱摇蚊和六附器德永摇蚊有垂直迁移习性,且这种迁移明显地影响了取样的结果.象六附器德永摇蚊在高温季节下迁、寒冷季节上移的现象罕见,它可作为一种热敏感指示生物。另外,计算出了三种摇蚊幼虫体长和体重的回归方程式。 相似文献
17.
Keita Kodama Yoshihiro Tajima Takamichi Shimizu Satoshi Ohata Hiroaki Shiraishi Toshihiro Horiguchi 《Marine pollution bulletin》2014
We investigated effects of severe hypoxia (dissolved oxygen <1 ml l−1) on recruitment of mantis shrimp Oratosquilla oratoria in Tokyo Bay. Ten-year field surveys were conducted to examine quantitative relationships in annual mean densities of larvae and juveniles, and spatial distribution of juveniles and severe hypoxia. There was no significant correlation between annual mean densities of larvae and juveniles, suggesting that mortality during larval or juvenile stages varies among years, which might have regulated abundance of young-of-the-year juveniles. Juvenile density was low in the severely hypoxic area, implying that hypoxia could affect survivals and spatial distribution of juveniles. Meanwhile, there are yearly fluctuations in juvenile density in normoxic areas of both northern and southern part of the bay. This evidence suggests that abundance of post-settled juveniles might have been determined by not only effects of hypoxia, but also other factors influencing mortality during the early life stages. 相似文献
18.
The River Elbe is one of the biggest streams carrying pollutants of all kinds into the North Sea. However, investigations of direct effects of the Elbe water on river life are not numerous. Early life stages of common whitefish and carp were reared under comparable conditions in water of the River Elbe, and in tap water, respectively. No direct effects on the viability of the fry could be found by observing mortality and growth rates in both treatments. Whitefish larvae were severely infested by parasitic ciliates which were able to build up a dense population in the river water. In these experiments life conditions for the protozoa seemed to be much better than in tap water. Mortality rates of early larvae of common whitefish were lower in the Elbe water than in tap water. Mortality, growth rate and starvation resistance of carp fry was equal in river and tap water. 相似文献
19.
The abnormally high surface temperatures in the world's oceans during 1997/1998 resulted in widespread coral bleaching and subsequent coral mortality. An experiment was performed to study the effects of this coral mortality as well as the influence of the structural complexity on fish communities on a Tanzanian coral reef. Changes in fish communities were investigated on plots of transplanted corals after 88% of these corals had died. A distinct shift in fish community composition was found, although diversity was not affected. Fish abundance rose by 39% mostly due to an increase in herbivores, which seemed to benefit from enhanced algal growth on the dead corals. Fish abundance, species diversity and community composition were also strongly influenced by the structural complexity provided by the live and dead corals. This suggests that a coral reef can support abundant and diverse fish populations also after the corals have died as long as the reef structure is sustained. 相似文献
20.
Muhling BA Roffer MA Lamkin JT Ingram GW Upton MA Gawlikowski G Muller-Karger F Habtes S Richards WJ 《Marine pollution bulletin》2012,64(4):679-687
The 2010 Deepwater Horizon oil spill impacted the northern Gulf of Mexico (GOM) during the spring spawning season of Atlantic bluefin tuna (BFT). Overlap between BFT spawning habitat and surface oil in the northern GOM was examined using satellite-derived estimates of oil coverage, and spawning habitat models. Results suggested that although eggs and larvae were likely impacted by oil-contaminated waters in the eastern GOM, high abundances of larvae were located elsewhere, especially in the western GOM. Overall, less than 10% of BFT spawning habitat was predicted to have been covered by surface oil, and less than 12% of larval BFT were predicted to have been located within contaminated waters in the northern GOM, on a weekly basis. Our results provide preliminary but important initial estimates of the effects of the spill on larval BFT mortality, as concern continues over the appropriate management responses to impacts of the spill. 相似文献