Little auks (Alle alle) breeding in a High Arctic fjord system: bimodal foraging strategies as a response to poor food quality?     

Harald Steen  Daniel Vogedes  Fredrik Broms  Stig Falk-Petersen  & Jørgen Berge 《Polar research》2007,26(2):118-125

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Resource Partitioning Among Planktivorous Fish Larvae and Fry in a Mediterranean Coastal Lagoon     

E. Gisbert  L. Cardona  F. Castelló 《Estuarine, Coastal and Shelf Science》1996,43(6):723-735

Resource partioning among the planktivorous stages of eight fish species occurring in a Mediterranean coastal lagoon was studied. Five species were migratory mullets that spawned in the sea (Liza ramada, L. aurata, L. saliens, Chelon labrosusandMugil cephalus), while the other three species were resident and spawned in the lagoon (Atherina boyeri, Cyprinus carpioandGambusia holbrooki).Mullet fry exhibited similar diets, based on the consumption of zooplanktonic Crustacea such as copepods and cladocerans, although adult chironomids were also important.Gambusia holbrookiandA. boyerifed on small prey such as copepod nauplii, copepodites and rotifers, whileC. carpioconsumed larger prey preferentially (cladocerans and copepods).According to the trophic overlap and niche width results, seven species pairs could be competing in the estuary, although further experimental evidence is still required.  相似文献   

Short- and long-term effects of shrub management on vegetation in the Monte, Argentina     

L.I Allegretti  C.B Passera  A.B Robles 《Journal of Arid Environments》1997,35(4):685-693

A comparison was made of plant cover, carrying capacity and diversity in areas of Monte vegetation at the Biosphere Reserve of Ñacuñán, Mendoza, Argentina, in 1982, 1984 and 1995. Treatments applied in 1981 were: control (untreated plots), selective hand-cutting, roller-chopping, and root-plowing. By 1995, woody cover was lower in root-plowed plots (27%) than in the others treatments (41–51%), and herbaceous cover was similar in treated (28–39%) and untreated areas (26%). Carrying capacity of treated areas (6–8 ha per Large Stock Unit (LSU)) was higher than in the control areas (12 ha LSU⁻¹). Woody species diversity, quantified by the Shannon index, for both areas was similar in the study period (0·62), except in root-plowed sites in 1982 (0·0) and 1995 (1·3). Herbaceous species diversity was similar on treated (0·81) and untreated sites (1·2) in 1995. We could recommend less drastic treatments to improve carrying capacity.  相似文献   

中国沿海部分地区半褶织纹螺的毒性及毒素组成分析     

罗璇  于仁成  王晓杰  周名江 《海洋与湖沼》2016,47(2):327-335

为确定中国沿海不同地区织纹螺中的毒素成分,本研究在江苏省、浙江省和福建省设立了多个采样点,对采集的半褶织纹螺样品进行了毒性测试和毒素组成分析。研究结果显示,采集的织纹螺样品毒性范围为2—664MU(mouse unit)/g湿重,其中,采自江苏省连云港地区的织纹螺样品毒性远高于其它地区。应用高效液相色谱-质谱联用(high-performance liquid chromatography-mass spectrometry,LC-MS)方法对样品中的毒素成分进行分析,在各地的织纹螺样品中均检测到了河豚毒素(TTX)及trideoxy TTX、4-epi TTX和anhydro TTX等衍生物,但各种毒素成分所占的比例存在差异。自江苏省连云港市和浙江省舟山市采集的织纹螺样品中,Trideoxy TTX是主要的毒素成分,TTX和其它两种毒素成分次之;而自江苏省盐城市、浙江省宁波市及福建省宁德市和莆田市采集的织纹螺样品中,TTX的含量最高。采集自江苏省连云港和浙江省舟山市的大部分织纹螺样品中,肌肉组织的毒素含量最高,其次是消化腺组织,其余组织中的毒素含量最低。高毒性成分TTX的最高值主要出现在肌肉组织或消化腺组织中。从实验结果可以看出,各地的有毒织纹螺中毒素成分基本一致,而各种毒素成分所占的比例有一定的差异,织纹螺的毒性与高毒性成分TTX的含量有关。  相似文献   

Growth and population parameters of ringed seals (Pusa hispida) from Svalbard, Norway, 2002-2004     

Krafft  Bjorn A.; Kovacs  Kit M.; Frie  Anne Kirstine; Haug  Tore; Lydersen  Christian 《ICES Journal of Marine Science》2006,63(6):1136-1144

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Retrospective analysis: bile hydrocarbons and histopathology of demersal rockfish in Prince William Sound,Alaska, after the Exxon Valdez oil spill     

Marty GD  Hoffmann A  Okihiro MS  Hepler K  Hanes D 《Marine environmental research》2003,56(5):569-584

Demersal rockfish are the only fish species that have been found dead in significant numbers after major oil spills, but the link between oil exposure and effect has not been well established. After the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, several species of rockfish (Sebastes spp.) from oiled and reference sites were analyzed for hydrocarbon metabolites in bile (1989-1991) and for microscopic lesions (1990 and 1991). Biliary hydrocarbons consistent with exposure to Exxon Valdez oil were elevated in 1989, but not in 1990 or 1991. Significant microscopic findings included pigmented macrophage aggregates and hepatic megalocytosis, fibrosis, and lipid accumulation. Site differences in microscopic findings were significant with respect to previous oil exposure in 1991 (P=0.038), but not in 1990. However, differences in microscopic findings were highly significant with respect to age and species in both years (P<0.001). We conclude that demersal rockfish were exposed to Exxon Valdez oil in 1989, but differences in microscopic changes in 1990 and 1991 were related more to age and species differences than to previous oil exposure.  相似文献   

Accretion of a New England (U.S.A.) Salt Marsh in Response to Inlet Migration, Storms, and Sea-level Rise     

C.T. Roman  J.A. Peck  J.R. Allen  J.W. King  P.G. Appleby 《Estuarine, Coastal and Shelf Science》1997,45(6):717-727

Sediment accumulation rates were determined at several sites throughout Nauset Marsh (Massachusetts, U.S.A.), a back-barrier lagoonal system, using feldspar marker horizons to evaluate short-term rates (1 to 2 year scales) and radiometric techniques to estimate rates over longer time scales (¹³⁷Cs,²¹⁰Pb,¹⁴C). The barrier spit fronting theSpartina-dominated study site has a complex geomorphic history of inlet migration and overwash events. This study evaluates sediment accumulation rates in relation to inlet migration, storm events and sea-level rise. The marker horizon technique displayed strong temporal and spatial variability in response to storm events and proximity to the inlet. Sediment accumulation rates of up to 24 mm year⁻¹were recorded in the immediate vicinity of the inlet during a period that included several major coastal storms, while feldspar sites remote from the inlet had substantially lower rates (trace accumulation to 2·2 mm year⁻¹). During storm-free periods, accumulation rates did not exceed 6·7 mm year⁻¹, but remained quite variable among sites. Based on¹³⁷Cs (3·8 to 4·5 mm year⁻¹) and²¹⁰Pb (2·6 to 4·2 mm year⁻¹) radiometric techniques, integrating sediment accumulation over decadal time scales, the marsh appeared to be keeping pace with the relative rate of sea-level rise from 1921 to 1993 of 2·4 mm year⁻¹. At one site, the²¹⁰Pb-based sedimentation rate and rate of relative sea-level rise were nearly similar and peat rhizome analysis revealed thatDistichlis spicatarecently replaced this onceS. patenssite, suggesting that this portion of Nauset Marsh may be getting wetter, thus representing an initial response to wetland submergence. Horizon markers are useful in evaluating the role of short-term events, such as storms or inlet migration, influencing marsh sedimentation processes. However, sampling methods that integrate marsh sedimentation over decadal time scales are preferable when evaluating a systems response to sea-level rise.  相似文献   

A First Generation Stochastic Bioeconomic Analysis of Algal Bloom Control in a Coastal Lagoon (Sacca di Goro, Po River Delta)     

Giulio Alessandro De  Leo  Marco Bartoli  Mariachiara Naldi  Pierluigi Viaroli 《Marine Ecology》2002,23(S1):92-100

Abstract. In this work we have developed a very simple stochastic mathematical model of Ulva spp. growth to quantitatively evaluate the economic costs of algal harvesting and the related benefits in terms of avoided'economic loss'of clam production due to an effective prevention of algal blooms and the consequent anoxic crises. Algal growth was simulated by means of a discrete time difference equation of Ulva biomass where the finite growth rate depends only upon water temperature. In order to explicitly include environmental variability, a seasonal autoregressive model calibrated on available data was used to simulate water temperature. Different harvesting scenarios were analysed in terms of the number of harvesting vessels employed and the threshold biomass of Ulva at which vessels start to operate. Costs of algal harvesting and disposal, as well as monetary damages resulting from the collapse of clam production as a consequence of algal blooms, were assessed by interviewing the managers of the Clam Fishermen's Union of Goro. A Monte Carlo approach was used to estimate the mean and total statistical distribution of costs and benefits of different harvesting strategies. Our analysis shows that the most cost-effective management policy is attained with 4–6 vessels operating at low algal density able to harvest as much Ulva as possible with intensive and short interventions at the beginning of the seasonal growth.  相似文献   

DNA adducts in mussels and fish exposed to bulky genotoxic compounds     

Dolcetti L  Zuanna LD  Venier P 《Marine environmental research》2002,54(3-5):481-486

Biological and procedural factors can influence DNA adduct detection in aquatic organisms. Among them, functional structure and metabolic traits represent major biological determinants for adducts formed by lipophilic pro-mutagenic contaminants. In detecting DNA adducts through the 32P-postlabelling assay, efficiency in DNA purification, digestion, labelling, as well as adduct enrichment and quantification may explain differences between independent studies. Reference DNA adducts have been used to verify some 32P-postlabelling aspects. Data obtained for mussels and fish treated with benzo[a]pyrene (B[a]P) and environmentally exposed to genotoxins confirm the above assertions. Although the 32P-postlabelling assay cannot be proposed for routine biomonitoring it appears a reliable and very sensitive index of exposure to genotoxic pollutants in both fish and mollusks.  相似文献   

Target Strength of encaged Atlantic redfish (Sebastes spp.)     

Gauthier  Stephane; Rose  George A. 《ICES Journal of Marine Science》2001,58(3):562-568

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