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1.
To overcome the problems of beach pollution Sydney Water constructed three deepwater sewage outfalls off North Head, Bondi and Malabar. The outfalls were commissioned over the period September 1990–July 1991. A 5-year multi-disciplinary environmental monitoring programme was set up to assess the impacts on the demersal fish and soft-bottom macro-invertebrate communities. Assessment of impact was based on an asymmetrical analysis of variance which provided an a priori orthogonal contrast between a single outfall and multiple control sites sampled before and after commissioning. Impacts were detected in both communities, included several commercially and recreationally important species of fish, and occurred with the greatest frequency in the soft-bottom community. The results are summarized, and several examples are presented and show that the direction and magnitude of the impacts varied among outfalls and taxa. The results are then discussed in terms of the needs of future monitoring and the implications for the assessment of human-induced impacts in other parts of the world.  相似文献   

2.
We evaluated the effects of fishway design and stream habitat on fish distribution and migrations within a 50 km section of the Enz River (108 km long, 16.7 m3 · s−1 mean annual discharge), a second order tributary of the Rhine River. On 12 different occasions between August 1994 and September 1995, we collected fish electrically upstream, downstream, and inside three different types of fish-passes: a concrete channel (site I), an artificial stream (site II), and a step and pool fishway (site III). During electrofishing, species identity and fish lengths were recorded separately for specific habitats or sections within the fishways, and traps were installed for 3–5 week long periods at the upstream outlets of the fishways. More than 3550 fish >5 cm and approximately 5800 young-of-year individuals of 28 species were captured. 772 fish marked by subcutaneous injection of alcian blue dye were released downstream of two fishways. Almost 1150 fish, including 5 marked individuals, were captured in the traps, providing direct evidence for migration through the fishway. The total number of species recorded decreased downstream from 21 at site I to 18 at site II, and 17 at site III. This shift in numbers and also in species composition between sites could be partially related to differences in the available habitat. There were pronounced changes in the abundance of most of the dominant species downstream and upstream of the fishway at site III, and, to a lesser degree at sites I and II, indicating species (and size) specific differences in the effectiveness of the three designs for fish passage. Furthermore, marked differences in relative fish abundance between downstream locations and inside the fishway itself, and in the relative numerical composition of the trap catch at sites I and II, clearly demonstrate that some species (Cottus gobio, Barbatula barbatula, Salmo trutta, Leuciscus cephalus) use these fishways as a habitat, whereas others (Phoxinus phoxinus, Gobio gobio) simply migrate through. Only inside the artificial stream did we find early life stages of seven species, suggesting that passage of the other fishways is restricted to older fish. Our results demonstrate that fishway design is crucial in providing continuous fish passage for all species and life-stages, and that a nature-like fishway is the most functional solution.  相似文献   

3.
Lake Breiter Luzin, located in north-eastern Germany, is known for the rare occurrence of sympatric populations of European cisco, Coregonus albula and C. lucinensis. Moreover, the lake is inhabited by the glacial relict crustacean Mysis relicta, currently found in only three other lakes in Germany. In the present study, the role of M. relicta in the diet of ciscoes was investigated. Between 2001 and 2002 ciscoes, mysids and zooplankton were caught in Lake Breiter Luzin and stomach contents of ciscoes were analysed. There were seasonal changes in the food items in the stomachs, largely reflecting changes in prey availability. The main food items were copepods (45–81%) and mysids (5–26%). Cladocerans had high amounts in the diet only in summer. Seasonal changes in selectivity were also noted for most prey groups. There were also some consistent patterns of prey preference, with an overall preference for mysids. In general, the prey composition in cisco stomachs did not show significant diet changes, but there were some significant differences between day and night feeding in single prey groups, such as cladocerans. Diet composition of ciscoes varied with the different depth strata in which the fish were caught. With increasing depth, the proportion of mysids in the diet significantly increased, whereas that of copepods significantly decreased. Between C. albula and C. lucinensis, no distinct differences in feeding were evident. Mysids provided an additional and important food resource to ciscoes, and were mainly consumed when the availability of other prey organisms decreased, as in autumn and in the deeper strata of the water column. However, mysids preyed on the same food organisms as ciscoes, indicating a strong competition for food between fish and mysids.  相似文献   

4.
Four species of marine calcifying algae, the coccolithophores Calcidiscus leptoporus, Helicosphaera carteri, Syracosphaera pulchra and Umbilicosphaera foliosa were grown in laboratory cultures under temperatures varying between 14 and 23 °C, and one species, C. leptoporus, under varying [CO32−], ranging from 105 to 219 μmol/kg. Calcium isotope compositions of the coccoliths resemble in both absolute fractionation and temperature sensitivity previous calibrations of marine calcifying species e.g. Emiliania huxleyi (coccolithophores) and Orbulina universa (planktonic foraminifera) as well as inorganically precipitated CaCO3, but also reveal small species specific differences. In contrast to inorganically precipitated calcite, but similar to E. huxleyi and O. universa, the carbonate ion concentration of the medium has no statistically significant influence on the Ca isotope fractionation of C. leptoporus coccoliths; however, combined data of E. huxleyi and C. leptoporus indicate that the observed trends might be related to changes of the calcite saturation state of the medium. Since coccoliths constitute a significant portion of the global oceanic CaCO3 export production, the Ca isotope fractionation in these biogenic structures is important for defining the isotopic composition of the Ca sink of the ocean, one of the key parameters for modelling changes to the marine Ca budget over time. For the present ocean our results are in general agreement with the previously postulated and applied mean value of the oceanic Ca sink (Δsed) of about − 1.3‰, but the observed inter- and intra-species differences point to possible changes in Δsed through earth history, due to changing physico-chemical conditions of the ocean and shifts in floral and faunal assemblages.  相似文献   

5.
The macrobenthos on the coastal reefs near the North Head deep-water outfall were sampled nine times over a 3 year period to determine whether patterns in diversity and abundance were affected by the outfall. The assemblages were sampled using an asymmetrical after control/impact design (ACI). Ten replicate quadrats at each of three sites nested within each of three locations were photographed using a jump camera. These photographs were sampled to provide estimates of the number and abundance of major taxa and abundances of individual species. Significant interactions between outfall vs control through time were detected for the total number of species, bryozoans, cnidarians and the abundances of a silt matrix and two species of bryozoans. Smaller scale interactions among sites through time occurred for the abundances of total fauna, sponges and an ascidian species representing some evidence for the effect of the outfall at these smaller spatial scales. This paper summarizes the correlative evidence of effects from the outfall.  相似文献   

6.
In 1981–83 sublittoral macroinvertebrates were collected by means of SCUBA diving from artificial substrates submerged near the outfalls from eight sewage treatment plants in Lake Zürich. Pollution around the outfall resulted on the one hand in a reduction of pollution intolerant benthic invertebrates, on the other hand in a considerable increase in the relative abundance of pollution tolerant taxa such as leeches, flatworms and crustaceans. Changes in the faunal composition were related to nutrient enrichment and changes in the nature of the substratum due to sedimentation of sewage sludge. Species diversity (Simpson index) showed low values near the outfall from some plants, high values near the outfall from others. Low species diversity did not always mark the sites where greatest pollution has been observed.   相似文献   

7.
内蒙古锡林郭勒盟盐湖浮游生物的群落特征   总被引：16，自引：6，他引：10  
通过2003年9月-2004年1月的渔获物调查,并结合1984-2002年的鱼类产量统计资料,分析了近二十年来太湖鱼类产量和组成的变化规律以及环境间的相互作用关系.结果表明,太湖鱼类的种类在不断减少,如本次调查和2002年3月-2003年12月的调查只采集到48种鱼类,和历史资源料比较有55种鱼类难以采到;鱼类产量组成表现为仅鲚鱼的产量和组成比例总体呈较快的上升趋势,从1984年的5153.7t、占总产量的36.2%上升到2002年的19571t、64.1%,鲤、鲫鱼基本维持不变,但近四年略有上升,其余鱼类均呈下降趋势.用Wilhm改进式计算的鱼类产量组成的均匀度指数H总体呈逐年下降趋势,近二十年来平均以每年-0.0465的速率下降;分析认为,人类活动以及由此引起的太湖生态环境变化,包括江湖阻隔、过渡捕捞、富营养化及太湖特有的鱼类生态学特点决定了鱼类组成的这一变化趋势:江湖阻隔、过度捕捞是引起太湖鱼类种类减少和鱼类组成发生巨大变化的主要原因;太湖近二十年来富营养化程度不断加重,由此使初级生产力水平持续增长,浮游生物饵料丰富,使鲚鱼等浮游生物食性鱼类产量逐年提高;舶鱼数量的减少又使鲚鱼失去抑制.随着鲚鱼等浮游动物食性鱼类产量的升高,太湖浮游动物的生物量呈下降趋势,这可能是太湖浮游植物数量倍增的生物学因素之一.目前太湖鱼类产量组成的变化正向着抑制浮游动物和有利浮游植物生长的方向发展.  相似文献   

8.
Zinc in muscle tissue from 28 species of fish, three species of sharks and rays, two species of squid and cuttlefish, and three species of crustacea collected from Cleveland Bay, together with some measurements made on oysters and mangrove flora and fauna are reported. In the fish species the mean Zn concentration in muscle tissue was 4.83 ± 2.82 μg/g wet weight, slightly lower than zinc measurements (7 μg/g wet weight) made in 14 fish species collected from the bay in 1975. Zinc in sharks and rays ranged from 3.5 to 7.2 μg/g wet wt, in squid and cuttlefish 13–16 μg/g wet wt, and in crustacea levels ranged from 14 to 18 μg/g wet wt. Zinc levels in fish varied between species with concentrations well below the ANZECC Maximum Residue Limit of zinc in seafood (150 μg/g wet wt). Although lower zinc concentrations were found in oysters collected from the Townsville Harbour area (2080 μg/g wet wt), compared with previous measurements made 25 years ago at this site, these levels are still above the Maximum Residue Limit for zinc in oysters (1000 μg/g wet wt). Concentrations of zinc in oysters from Orpheus Island (2547 μg/g wet wt), about 74 km away from industrial and urban activity, are also above the safe guideline values. Horseshoe Bay oysters transplanted to Ross Creek accumulated zinc at a rate of about 100 μg/g of oyster tissue per week, suggesting that dissolved zinc levels at this site are elevated, and that oysters rapidly accumulate zinc. Highest concentrations of zinc in mangrove leaves (30–65 μg/g dry wt) occurred in Osbornia octodonta, Exocaria agalocha, and Aegialitus annulata, compared with Ceriops tagal, and Avicennia marina (5–10 μg/g dry wt). No significant difference in zinc concentration occurred between leaves and litter fall for most of these species, with the sole exception of Exocaria, which showed almost a twofold increase in concentration. In seven species of mangrove fauna levels of zinc were very uniform and close to 50 μg/g (dry wt) Telescopium telescopium from the mouth of the Ross Estuary was the exception with levels at 400 μg/g (dry wt).  相似文献   

9.
Studies of the impact of secondary treated domestic effluent have been conducted at Coffs Harbour, NSW, Australia for the last 8 years. During that time, monitoring has shown that impacts are restricted to within approximately 300 m of the outfall for most variables (e.g. algal species richness, changes to the structure of invertebrate communities living in kelp holdfasts) but that the ephemeral green alga Ulva lactuca has significantly greater cover than at reference sites for a distance of 500 m from the point of discharge. Based on the results of this study, a new outfall proposed for the northern area of Coffs Harbour was predicted to have effects over a much smaller spatial scale. It is suggested, therefore, that the recent decision to abandon the plans for the new outfall reflects growing public concern over issues other than cost minimization and biological impact in the use of ocean disposal as an option for the management of human sewage waste.  相似文献   

10.
A total of 51 potential pathogenic vibrios were isolated from moribund silver sea bream (Sparus sarba) collected from fish farms in Hong Kong. Using the API 20E system and the scheme of Alsina and Blanch (1994), 7 species were identified from all isolates. These species were Vibrio alginolyticus (24 strains), Vibrio vulnificus (12 strains), Vibrio parahaemolyticus (7 strains), Vibrio logei (4 strains), Vibrio pelagius II (2 strains), Vibrio fluvialis (1 strain) and Vibrio meditterranei (1 strain). The three dominant species (V. alginolyticus, V. vulnificus and V. parahaemolyticus) were confirmed to be virulent to sea bream by experimental challenge.

All isolates were screened for plasmid DNA by agarose gel electrophoresis and tested for susceptibility to 16 antibiotics by the agar dilution method. Of the 51 isolates examined, all strains were sensitive to ceftriaxone, streptomycin, nalidixic acid and rifampicin, and almost all were sensitive to ceftazidime, netilimicin, chloramphenicol and sulfamethoxazole. Most isolates were resistant to ampicillin (60.8%), cefuroxime (66.7%), amikacin (55%), kanamycin (58.8%) and trimethoprim (76.5%). Fifteen of the 51 isolates harboured 1–4 plasmids, with sizes ranging from 9 to 123 kb. Both the plasmids and the associated antibiotic resistance (ampicillin, cefuroxime and trimethoprim) of 9 isolates could be transferred to a recipient by single-step conjugation. However, the frequencies were very low, ranging from 10−11 to 10−9. The present results indicate that resistance to these antibiotics is chromosomal.  相似文献   


11.
Dynamite damage was investigated on 60 reefs in the Egyptian Red Sea. 65% of the investigated reefs had signs of dynamite damage, mostly in leeward areas (58%). Significant changes in coral and fish community composition within dynamited sites were observed. Coral cover decreased, the amount of bare substratum and rubble increased, fish communities in dynamited areas suffered a decrease in species richness and abundance. Due to a stable pattern of coral community differentiation on northern Red Sea reefs (windward Acropora, leeward Porites) most damage is on near-climax Porites reef slopes or Porites carpets. Natural regeneration of such communities is likely to be very slow, possibly taking several hundred years. Rehabilitation would be difficult since coral transplants would have to mimic the previously existing community.  相似文献   

12.
The impact of tar aggregates deriving from the Haven oil spill that occurred in 1991 on the soft-bottom macrobenthos off Arenzano (Ligurian Sea, NW Mediterranean; Italy) was investigated in this study. Core samples were collected to evaluate the composition, abundance and stratification of macrobenthos in three contaminated and three control sites. The distribution of tar aggregates (often settled by hydroids, bryozoans and serpulids) in the impacted area did not show distinct patterns related to sediment depth. The macrobenthos was numerically dominated by polychaetes, followed by crustaceans (amphipods, isopods and tanaids) and sipunculids, whereas bivalve molluscs were less represented. Ophiuroids and nemerteans were only occasionally found. Stratification was the main factor explaining the distribution of benthic invertebrates, highest abundances being observed in the upper 5 cm of sediment, while densities of individuals declined sharply in deeper sediment layers. No significant differences were observed in the abundance of both the whole benthic assemblage and of the main benthic taxonomic groups between contaminated and control sites. The higher abundance of sipunculids at the contaminated sites, instead, was attributed to the availability of empty tubes of polychaetes in which they take refuge. The polychaetes/amphipods ratios did not show strong differences between impacted and control sites. Multivariate analysis (MDS) showed a wide scattering among deep bottom samples and a comparatively high similarity among intermediate and superficial layers, regardless of the contamination level. In conclusion, the results reported here suggest that tar aggregates do not determine appreciable detrimental effects on the soft-bottom macrobenthos, which appeared to have recovered towards natural pristine conditions.  相似文献   

13.
Imposex, or the presence of a pseudopenis in female snails, is quantified by comparing the length of the female pseudopenis with the male penis. However, many muricid gastropods in the Malayan archipelago possess penes that are flagellate and coiled, making linear measurement difficult under the microscope. In addition, it is unclear if penis length is dependent on shell size. Accurate assessment of penis size is a necessary step towards determining the severity of imposex (and implicitly, the amount of organotins from antifouling paints that is associated with this phenomenon). Two mangrove muricid gastropod species, Thais gradata and Chicoreus capucinus, were collected from six sites along the Johor Straits. Penis/pseudopenis length and area measurements based on digitalized camera lucida drawings were generally well correlated with penis/pseudopenis dry weight, although penis area appeared to be a marginally better variable than penis length for T. gradata. Penis dry weight was also well correlated with shell height in male T. gradata, while no significant correlation was detected for female T. gradata, suggesting pseudopenis size alone may be a better measure of imposex than the relative penis size index (RPSI) for this species. There was no obvious relationship between penis size and shell height for either sex in C. capucinus.  相似文献   

14.
由于自然和人为因素的影响,三峡水库鱼类资源一直在发生变化,为掌握三峡水库蓄水后典型支流香溪河鱼类群落的现状及历史变化,于2020年7月—2021年4月使用多网目复合刺网和地笼对香溪河鱼类群落进行实地采样,并结合历史数据进行比较分析。研究期间共采集到鱼类55种,隶属于7目14科,鲤科鱼类种类数最多,以杂食性鱼类和湖泊定居性鱼类为主,优势种为贝氏?(Hemiculter bleekeri)、短颌鲚(Coilia bratchygnahus)、似鳊(Pseudobrama simoni)和翘嘴鲌(Culter alburnus),其相对重要性指数(IRI)分别为5502、3828、2567和1109。鱼类物种多样性指数在春季最高,夏季最低。刺网单位捕捞努力量渔获个体数和单位捕捞努力量渔获量在夏季最高,冬季最低。与三峡水库蓄水前相比,香溪河鱼类中长江上游特有鱼类减少4种,外来鱼类增加3种。湖泊定居性种类持续增加,喜流水性种类减少,鱼类优势种发生较大变动。2020—2021年香溪河鱼类组成与1987年的相似性指数为0.29,与2012—2013年的相似性指数为0.53,反映三峡水库蓄水前后香溪河...  相似文献   

15.
The population dynamics and distribution of Daphnia pulicaria were studied in Lake Constance (Lower Lake). This Daphnia was absent in the year 2004, absent during most part of the year 2005 and absent in spring 2007 but present from November 2005 to July 2006. Abundance was high from January to late May of the year 2006; maximum abundance was 95,000 ind. m−2 (30 May). Males and ephippial females were observed in January and late May. Ovigerous females constituted between 30% and 70% of adult females from November 2005 to April 2006; in June and July their percentage decreased to <20%. Mean number of eggs per egg-bearing female ranged between 2 (in November 2005) and 9.8 (in April 2006) and maximum egg number was 20. Birth and growth rates were low (generally <0.15); death rate was highest in June (0.275). Females of D. pulicaria were larger than females of Daphnia galeata/hyalina but carried somewhat fewer eggs. D. pulicaria generally preferred the deep cool water layers. The species was abundant in the northern parts of the Lower Lake (Gnadensee and Zeller See), rare in the southern parts (Rheinsee) and absent in the Upper Lake. We conclude that the life history and occurrence of large-bodied D. pulicaria in Lake Constance can be governed by fish predation pressure. This suggestion is supported by analyses of stomach contents from Coregonus lavaretus; stomachs contained high proportions of D. pulicaria in the first half of the year 2006. The disappearance of D. pulicaria in early summer and the comparatively low proportion of adults for most part of the investigation period also indicate that fish predation is involved in the dynamics of this Daphnia. The preference for deep cool water can be strategy to reduce predation risk. The low density of D. pulicaria in the southern basin of Lower Lake (Rheinsee) may be explained by the influence of the Rhine River which flows through this basin.  相似文献   

16.
Most assessments of fish contamination in Southern California use ecologically different species from different sites. Use of ecologically similar species (a guild) might provide better assessments of fish contamination across different sites and depths. In July-August 1997, we collected samples of four sanddab guild species at 22 sites where species pairs co-occurred and determined total DDT concentrations in homogenized whole fish composites. Log-transformed DDT concentrations were highly correlated among all species pairs within this guild. All relationships were linear over the range observed, with slopes not statistically different from unity. The variability in response among species was about four times the variability encountered among replicates within species, but 15 times smaller than the variability among sites. Together, these results suggest that the sanddab guild, widespread on soft bottoms of the Southern California coastal shelf, can be used as a "superspecies" in bathymetrically diverse regional assessments of fish tissue contamination.  相似文献   

17.
黄河伊洛河中下游鱼类多样性及群落结构   总被引：1，自引：0，他引：1  
为了解伊洛河中下游鱼类多样性、群落结构及其与环境因子的关系,于2016年2-12月对伊洛河中下游5个河段开展鱼类多样性及环境调查.共采集鱼类12361尾,43种,隶属于4目9科37属.伊洛河中下游鱼类群落的Shannon-Wiener多样性指数、Margalef丰富度指数、Pielou均匀度指数和Simpson指数变化范围分别为1.75~2.38、2.44~3.63、0.59~0.76和0.73~0.86.各指数均以西草甸河段最高.各河段优势种以（Hemiculter leucisculus）、似鳊（Pseudobrama simoni）、鲫（Carassius auratus）、兴凯鱊（Acheilognathus chankaensis）和鳑鲏属（Rhodeus）等小型或广适性鱼类为主.丰度/生物量比较（ABC）曲线显示,除西草甸河段外,各河段优势鱼类群落均受到不同程度的干扰.其中七里铺和黑石关鱼类群落处于严重干扰状态,以小型鱼类或大型鱼类的幼鱼为主.采用冗余分析方法分析了鱼类群落结构与环境因子的关系,发现除了河床、水流、捕捞等因子以外,氨氮、总磷浓度与pH是导致伊洛河中下游鱼类群落结构差异的主要影响因子.针对伊洛河鱼类多样性现状,建议加强流域水质监管,恢复河流连通性,推进保护区全面禁渔,开展生态修复等以恢复伊洛河河流健康.  相似文献   

18.
A suite of six biomarkers was measured in shore crabs (Carcinus maenas) and mussels (Mytilus edulis) deployed at, or native to, the Tees Estuary in north-east England, as well as at several control sites. LC-50 tests on water samples from the field sites were carried out using the marine copepod Tisbe battagliai and Microtox™ assays. Biomarker responses varied among the sites. Results were analysed using novel multivariate statistical procedures. A clearer overall picture was obtained from multi-dimensional scaling plots than by examining the data for different biomarkers individually. It was possible to distinguish among contaminated and control sites, with the contaminated sites being further differentiated to reflect a pollution gradient. It was concluded that multi-dimensional scaling procedures are a valuable additional tool for improving the analysis and interpretation of complex suites of biomarker data.  相似文献   

19.
Sediment disturbance patterns in the coastal area off the Tagus Estuary (Portugal) have been assessed using a set of combined techniques. The potential sources of disturbance in the area include chronic contamination of the fine sediments originating from the estuary, a local input from a long-sea sewage outfall and occasional high runoff episodes following torrential rain. The Sediment Quality Triad approach, combining environmental chemistry (namely organic contaminants), macrofaunal benthic communities and laboratory sediment toxicity assays, was performed on sediment samples from 20 sites. The samples were collected before the outfall commenced operation and four years after commissioning, in order to evaluate the relative magnitudes of the three potential sources of disturbance. The sediment contamination created by the estuary was identified as the most important cause of reduced sediment quality, as disturbance in all three components of the Sediment Quality Triad were only found in a site located near the estuary.  相似文献   

20.
Organochlorines in Hong Kong Fish   总被引：6，自引：0，他引：6  
Muscle samples from 15 species of fish (n=1) purchased from markets in Hong Kong and 10 liver samples of tilapia (Tilapia mossambica) collected from the Shing Mun River were analysed for organochlorines (polychlorinated biphenyls, ΣDDTs, hexachlorobenzene, hexachlorocyclohexanes, chlordanes, mirex and dieldrin). Polychlorinated biphenyls (PCBs) were detected in 15 market fish samples but the levels were very low (around 1 ng g−1). PCB levels in tilapia livers collected from Tai Wai (29.3–65.1 ng g−1) were higher than those from Fo Tan (3.5–23.2 ng g−1) suggesting that there may be some local point soucres. ΣDDTs were detected in all samples, ranging from 3.3 to 75.6 ng g−1 in the market fish and from 7.1 to 88.8 ng g−1 in tilapia. The DDE/DDT ratios in the market fish (0.12–0.75) showed higher variability than those of tilapia (0.30–0.46), suggesting that some of the market fish may have been collected from areas where DDT was recently used. Results of this preliminary study show that organochlorine levels in Hong Kong market fish are low and do not cause any concern for human consumption. An on-going monitoring program, however, is recommended.  相似文献   

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