广西金钟山自然保护区鱼类资源考察报告

2004年11月14日至12月17日，在广西金钟山自然保护区内水域中共获淡水鱼类样品110余号，结合以往的调查资料。初步确定保护区淡水鱼类共有52种，分别隶属于4目13科1．45属．通过对保护区鱼类资源的实地考察，从生态区系的角度叙述了保护区野生鱼类资源的区系概况和分布特点，并对保护区鱼类资源的管理和合理利用提出了建议。     

Non-Native Fish Introductions and the Decline of the Mountain Yellow-Legged Frog from within Protected Areas

Abstract: One of the most puzzling aspects of the worldwide decline of amphibians is their disappearance from within protected areas. Because these areas are ostensibly undisturbed, habitat alterations are generally perceived as unlikely causes. The introduction of non-native fishes into protected areas, however, is a common practice throughout the world and may exert an important influence on amphibian distributions. We quantified the role of introduced fishes (several species of trout) in the decline of the mountain yellow-legged frog (   Rana muscosa ) in California's Sierra Nevada through surveys openface> 1700 sites in two adjacent and historically fishless protected areas that differed primarily in the distribution of introduced fish. Negative effects of fishes on the distribution of frogs were evident at three spatial scales. At the landscape scale, comparisons between the two protected areas indicated that fish distribution was strongly negatively correlated with the distribution of frogs. At the watershed scale, the percentage of total water-body surface area occupied by fishes was a highly significant predictor of the percentage of total water-body surface area occupied by frogs. At the scale of individual water bodies, frogs were three times more likely to be found and six times more abundant in fishless than in fish-containing waterbodies, after habitat effects were accounted for. The strong effect of introduced fishes on mountain yellow-legged frogs appears to result from the unique life history of this amphibian which frequently restricts larvae to deeper water bodies, the same habitats into which fishes have most frequently been introduced. Because fish populations in at least some Sierra Nevada lakes can be removed with minimal effort, our results suggest that the decline of the mountain yellow-legged frog might be relatively easy to reverse.     

Water, Endangered Fishes, and Development Perspectives in Arid Lands of Mexico

Nearly half of Mexico is arid or semiarid, with scarce waters. At least 92 springs and 2500 km of river have dried in this area. Surface waters have diminished, and phreatic waters are sinking deeper, provoking intrusion of saline waters and salinization of agricultural wells in Sonora, reversing phreatic circulation in the Comarca Laguenera, allowing arrival of arsenic to agricultural waters, and threatening metropolitan Torreón. There are nearly 200 species of freshwater fishes in this region, 120 under some threat, 15 extinct through human impact. As of 1985, an average of 68% of species was eradicated in local fish faunas. Finally, salinization of the lower Rio Bravo del Norte has replaced 32 native fish of fresh or slightly brackish water with 54 mainly marine or highly salt-tolerant species; the salinization threatens all uses of water. Some marine fishes invade up to 400 km upstream. Pollution is strong, and fish kills have been reported. These low-quality and scarce waters comprise future resources for cities such as Monterrey, which, along with its border twin cities, is expected to double its human population by 2010. Redesign of regional development is urgently needed, in keeping with the real availability of water. All water use should be equal to or less than lower recharge averages; norms of integral basin management should rely on criteria of high-use efficiency, recuperation, recycling, and reutilization. Also necessary are reduced pollution and increased treatment of residual waters. Innovative environmental vision is especially essential in light of expectations for development through the North American Free Trade Agreement, the Border Integral Environmental Plan, industrial expansion, and the modernization and internationalization of the northern Mexican border belt. These all conflict with the high priority recently decreed for species conservation by the Mexican Act, creating the National Committee on Knowledge and Use of Biodiversity.     

皮质醇影响青鳉鳃内钠钾ATP酶基因表达的研究

目前河流中存在较高浓度的天然和人造糖皮质激素(如皮质醇等)污染,其可能对鱼类的渗透压调节和海河洄游产生影响.鱼类鳃内钠钾ATP酶对调节渗透压平衡、适应海河洄游等起关键性作用,有研究表明鱼类鳃内钠钾ATP酶基因表达受皮质醇调控.为此,论文克隆了青鳉钠钾ATP酶α和钠钾ATP酶β基因的序列片段,建立了实时定量RT-PCR测定方法,研究了盐度的增加对其基因表达的影响,并重点探讨了皮质醇对鱼类适应盐度时鳃内钠钾ATP酶基因表达变化的影响.结果表明,适应15‰盐水的青鳉鳃内钠钾ATP酶α和钠钾ATP酶β基因表达显著升高;在转入淡水48h后,钠钾ATP酶α和钠钾ATP酶β基因表达基本恢复到正常水平,但是转入含有100ng·L-1皮质醇暴露水平的淡水中,48h后钠钾ATP酶α基因表达仍处于较高水平,表明100ng·L-1浓度的皮质醇能够显著诱导鳃内钠钾ATP酶α的基因表达,可能干扰渗透压调节,对一些洄游鱼类的溯河过程可能构成潜在影响.     

Wildlife Loss through Domestication: the Case of Endangered Key Deer

Abstract:  Wildlife extinction represents the ultimate failure of wildlife conservation. It has many causes, some of them natural, but is increasingly tied to anthropogenic factors. Wildlife loss via domestication, however, is rarely considered. We evaluated the potential for inadvertent domestication of wildlife by determining the effect of feeding and watering on Key deer ( Odocoileus virginianus clavium ) density, group size, and distribution. Key deer sightings were significantly higher in areas (42 ha) surrounding the households that provided food and water (0.18 deer/m;  n = 8   ) than in randomly selected areas (0.03 deer/m;  t = 3.82, 14  df, p = 0.002   ). Average distance to a household providing food and water decreased logistically as group size increased, and large groups (>2 individuals each) were observed more frequently in areas where food and water were provided (27.5%) than in the randomly selected areas (7.5%). The incidence of large groups outside feeding areas (7.5%), however, was similar to the incidence of large groups during early urbanization (5.1%; 1968–1973). Our results suggest illegal feeding caused changes in density, group size, and distribution indicative of domestication. Because fresh water and food were primary selective pressures for Key deer before illegal feeding and watering, genetic changes may occur in the future. For those who value "wildness" in wildlife, domestication of wildlife species is a serious problem that must be addressed.     

A Regional Perspective on the Diversity and Conservation of Tropical Andean Fishes

Abstract: The tropical Andes harbor an extraordinarily varied concentration of species in a landscape under increasing pressure from human activities. Conservation of the region's native plants and animals has received considerable international attention, but the focus has been on terrestrial biota. The conservation of freshwater fauna, particularly the conservation of fishes, has not been emphasized. Tropical Andean fishes are among the most understudied vertebrates in the world. We estimate that between 400 and 600 fish species inhabit the diverse aquatic environments in the region. Nearly 40% of these species are endemic. Tropical Andean fishes are vulnerable to ongoing environmental changes related to deforestation, water withdrawals, water pollution, species introductions, and hydropower development. Additionally, their distributions and population dynamics may be affected by hydrologic alterations and warmer water temperatures associated with projected climate change. Presently, at least three species are considered extinct, some populations are endangered, and some species are likely to decline or disappear. The long‐term persistence of tropical Andean fishes will depend on greater consideration of freshwater systems in regional conservation initiatives.     

Fresh water fishes as indicators of Kaveri River pollution

The survey of fish fauna in Kaveri River at polluted and unpolluted sites revealed a direct effect on the distribution of fishes in that 14 species were observed in unpolluted site and only 6 species in polluted site. Further, the haemotological parameters like RBC, WBC and haemoglobin content increased in fishes collected from polluted site whereas the organic constituents of muscle decreased in the above fishes when compared to the fishes of unpolluted site. The reason for the above changes is discussed.     

Ecological Impact of Introduced Crayfish on Benthic Fishes in a British Lowland River

Pacifastacus leniusculus (Dana), a native crayfish of western North America, was introduced into the U.K. in 1976. Our study examined some interactions between P. leniusculus and benthic fish in a British lowland river, the River Great Ouse. In a river survey an inverse correlation was found between the abundance of crayfish and the two dominant benthic fishes, bullhead (Cottus gobio L.) and stone loach (   Noemacheilus barbatulus [L.]) in six riffles. The benthic fishes were least abundant in the riffle nearest the original site of crayfish introduction and gradually increased in abundance both up and down river as crayfish abundance decreased. The hypotheses that crayfish compete with bullheads and stone loach for shelter and prey on fish were tested by laboratory experiments in an outdoor artificial stream (6 × 2 m) with recirculating water and 12 artificial shelters on the bottom. In competition experiments 12 fish of one species were alternatively kept alone and with 12 crayfish for 3-day cycles lasting a total of 12 days. The results showed that crayfish out-competed both fish species for shelter. Predation was measured by keeping 24 fish of each species alone and with 36 crayfish for 10 days respectively in the artificial stream. The mortalities of both fish species were significantly higher when crayfish were present. The loss of fish could be partly due to predation because crayfish guts contained the remains of some lost fish and they were observed preying on both fishes in a tank. In the river crayfish lived at high densities reaching ≥ to 20 m⁻² in riffles, and they continued to disperse. This may lead to a great reduction in benthic fish abundance if not local extinctions.     

Restoring native fish assemblages to a regulated California stream using the natural flow regime concept

We examined the response of fishes to establishment of a new flow regime in lower Putah Creek, a regulated stream in California, U.S.A. The new flow regime was designed to mimic the seasonal timing of natural increases and decreases in stream flow. We monitored fish assemblages annually at six sample sites distributed over approximately 30 km of stream for eight years before and nine years after the new flow regime was implemented. Our purpose was to determine whether more natural stream flow patterns would reestablish native fishes and reduce the abundances of alien (nonnative) fishes. At the onset of our study, native fishes were constrained to habitat immediately (<1 km) below the diversion dam, and alien species were numerically dominant at all downstream sample sites. Following implementation of the new flow regime, native fishes regained dominance across more than 20 km of lower Putah Creek. We propose that the expansion of native fishes was facilitated by creation of favorable spawning and rearing conditions (e.g., elevated springtime flows), cooler water temperatures, maintenance of lotic (flowing) conditions over the length of the creek, and displacement of alien species by naturally occurring high-discharge events. Importantly, restoration of native fishes was achieved by manipulating stream flows at biologically important times of the year and only required a small increase in the total volume of water delivered downstream (i.e., water that was not diverted for other uses) during most water years. Our results validate that natural flow regimes can be used to effectively manipulate and manage fish assemblages in regulated rivers.     

The use of clear-water non-estuarine mangroves by reef fishes on the Great Barrier Reef

Within the tropics, mangroves and coral reefs represent highly productive biomes. Although these habitats are often within close proximity, the role and importance of mangrove habitats for reef fish species remains unclear. Throughout the Indo-Pacific, reef fish species appear to have few links with estuarine mangrove habitats. In contrast, clear-water non-estuarine mangrove habitats throughout the Caribbean support many reef fish species and may be fundamental for sustaining reef fish populations. But how important are clear-water non-estuarine mangroves for reef fishes within the Indo-Pacific? Using visual surveys during diurnal high tide, the fish assemblages inhabiting clear-water mangrove and adjacent reef habitats of Orpheus Island, Great Barrier Reef, were recorded. Of the 188 species of fishes that were recorded, only 38 were observed to inhabit both habitats. Of these, only eight were observed more than five times within each habitat. These observations provide little indication that the clear-water mangroves are an important habitat for reef fish species. In addition, although based on just a 3-month survey period, we found little evidence to suggest that these areas are important nurseries for reef fish species. The clear-water mangroves of Orpheus Island may, however, provide an additional foraging area for the few reef fish species that were observed to utilize these habitats during high tide. The difference in the importance of clear-water mangroves for reef fishes within this study compared with clear-water mangrove counterparts within the Caribbean is surprising. Although only preliminary, our observations would support suggestions that the patterns reflect the different hydrological characteristics and evolutionary histories of these two biogeographic regions.     

Impact of linear alkyl benzene sulphonate (LAS) on phosphatase activity in testis of the teleostean fish,Heteropneustes fossilis (Bloch)

Fishes are sensitive indicators of pollutants present in water.These pollutants cause various physical and physiological alterations in fishes. In the present work alteration in the activity of acid and alkaline phosphatase was evaluated in testicular tissue of fresh water fish Heteropneustes fossilis exposed to LC50 value of linear alkyl benzene sulphonate (LAS) for different exposure periods [24 h, 48 h, 72 h and 96 h] With increase in the concentration of chemical LAS, the activity of acid phosphatase (ACP) was reported elevated while a significant fall in the activity of alkaline phosphatase (ACP) was recorded for same exposure period. Elevated activity of ACP, one of the important hydrolases of lysosomes, is quite suggestive of bringing about gross necrosis and dysarchitecture. ALP is involved in various metabolic activities including gonadal maturation and as such decreased activity of this enzyme is definitely one of the important causative factors for reproductive impairment of the fish.     

Predation on penaeid prawns by fishes in Albatross Bay,Gulf of Carpentaria

Fishes were trawled from Albatross Bay, on the west coast of Cape York, north Queensland (12°45S; 141°30E) during 4 yr, from August 1986 to April 1989. Penaeids were the first or second most important prey item by dry weight in 14 of the 34 penaeid-eating fish species, and in 12 of the species by frequency of occurrence. Eighteen species of Penaeidae were identified in fish stomachs. The five commercially important species comprised over 70% by dry weight of all the penaeids eaten by all the fishes;Metapenaeus ensis, Penaeus semisulcatus andP. merguiensis comprised 22, 28 and 11%, respectively. Commercially unimportant penaeids comprised 85% by numbers of all penaeids eaten. Larger fishes ate larger penaeids, mainly commercially important species, while smaller fishes ate smaller penaeids, mainly commercially unimportant species. All penaeid-eating fishes also ate some teleost prey and many were primarily piscivorous. Most penaeid-eating fish species took more benthic prey than bentho-pelagic and pelagic prey combined. The fishes with the strongest predation impact on commercially important penaeids wereCaranx bucculentus and four species of elasmobranchs. The highest impact on commercially unimportant penaeids was made by several species of smaller but abundant fishes. An overall annual estimate of 2950 t yr^–1 of commercially important penaeids is eaten by all fishes, a much higher figure than the average 870 t yr^–1 taken by the fishery. This study highlights the need for accurate measurement of the abundance of penaeid predators as well as analyses of their diets when assessing the impact of predators on prawn stocks.     

Comparison of the feeding habits of migratory and non-migratory Stenobrachius leucopsarus (Myctophidae)

Stenobrachius leucopsarus, the most abundant species of myctophid fishes off Oregon, USA, has a bimodal distribution at night, with a peak of abundance in the upper 100 m composed of diel vertical migrants, and another peak at 300 to 500 m composed of fish that did not migrate the night they were caught. We compared the feeding habits of these two groups of fish in an attempt to learn if deep fish migrated to surface waters. Low similarity of diets, differences in the rank order of common prey, and similar states of stomach fullness and digestion of prey suggest that fish captured in deep water at night probably did not feed exclusively in shallow water on previous nights. They probably fed in deep water. The similarity in food habits between deep and shallow fish is most readily explained by daytime feeding by fish in deep water and by broad vertical distributions of prey.     

Fish population dynamics in a seasonally varying wetland

Small fishes in seasonally flooded environments such as the Everglades are capable of spreading into newly flooded areas and building up substantial biomass. Passive drift cannot account for the rapidity of observed population expansions. To test the ‘reaction-diffusion’ mechanism for spread of the fish, we estimated their diffusion coefficient and applied a reaction-diffusion model. This mechanism was also too weak to account for the spatial dynamics. Two other hypotheses were tested through modeling. The first—the ‘refuge mechanism’—hypothesizes that small remnant populations of small fishes survive the dry season in small permanent bodies of water (refugia), sites where the water level is otherwise below the surface. The second mechanism, which we call the ‘dynamic ideal free distribution mechanism’ is that consumption by the fish creates a prey density gradient and that fish taxis along this gradient can lead to rapid population expansion in space. We examined the two alternatives and concluded that although refugia may play an important role in recolonization by the fish population during reflooding, only the second, taxis in the direction of the flooding front, seems capable of matching empirical observations. This study has important implications for management of wetlands, as fish biomass is an essential support of higher trophic levels.     

Factors influencing community structure and distribution of different life-cycle categories of fishes in shallow waters of a large Australian estuary

Fish were collected at regular intervals over 5 yr (February 1977 to December 1981) from ten shallow-water sites located throughout the lower, middle and upper regions of the large Swan Estuary in temperate southwestern Australia. Analysis of the catch data showed that the total number of species and total density of fishes were both influenced to a greater extent by site and season within the estuary than by year. The number of species and density of fishes within the whole system were greatest during the summer and autumn, when salinities and temperatures were at a maximum, and declined with distance from the estuary mouth. This reflects the trends shown by marine species, which comprise many species that occur only occasionally in the estuary (marine stragglers) and others which enter estuaries regularly and in considerable numbers (marine estuarine-opportunists). The density of marine estuarine-opportunists was also correlated with temperature, reflecting the tendency for the species of this category to congregate in the shallows during the summer and autumn. The similar seasonal aggregations of the single anadromous species and representatives of species that complete their whole life cycle in the estuary were frequently related to spawning. The density of the estuarine category was correlated neither with salinity nor distance from the estuary mouth. The number of estuarine species was also not correlated with distance from the estuary mouth. The density of freshwater species was inversely correlated with salinity and positively correlated with distance from the estuary mouth. The composition of the fish fauna changed progressively through the estuary, with that of the lower estuary being the most discrete. The composition also changed seasonally, particularly in the upper estuary where, during the winter and spring, the volume of freshwater discharge increased greatly and as a consequence the salinity declined markedly. The species diagnostic of the lower estuary were generally marine estuarine-opportunists, whereas those of the upper estuary typically belonged to either the estuarine or anadromous categories. The marine estuarine-opportunistMugil cephalus was, however, also one of the diagnostic species in the upper estuary during the winter and spring.Please address all correspondence and requests for reprints to I. C. Potter at Murdoch University     

铜对水生生物的毒性:类群特异性敏感度分析

铜的毒性因受多种环境因素(如温度、pH等)的影响,其水质基准和标准经历过多次修改。由于不同区系生物受生活环境等因素的影响,不同物种对铜的耐受性和敏感度上存在很大的差异。本文通过构建类群特异性敏感度分布,以及对10%安全浓度值(10%hazardous concentration,HC_(10))及其95%置信区间(95%confidence interval,95%CI)的比较,分析了铜对淡水和海水各类群的敏感度差异,以期为我国在制定相关水质基准的物种选择上提供参考。结果显示,淡水系统中藻类为对铜毒性最敏感类群,其次为甲壳类,软体动物类,鱼类,寡毛类,而昆虫类为对铜的最耐受类群。海水各类群对铜的敏感度顺序与淡水类似,只是在寡毛类和鱼类顺序上有所不同。相对于海洋物种,淡水水体生物总体上比海水中各相应类群生物对铜更为敏感。     

Role of the fish Astyanax aeneus (Characidae) as a keystone nutrient recycler in low-nutrient neotropical streams

Nutrient recycling by animals is a potentially important biogeochemical process in both terrestrial and aquatic ecosystems. Stoichiometric traits of individual species may result in some taxa playing disproportionately important roles in the recycling of nutrients relative to their biomass, acting as keystone nutrient recyclers. We examined factors controlling the relative contribution of 12 Neotropical fish species to nutrient recycling in four streams spanning a range of phosphorus (P) levels. In high-P conditions (135 microg/L soluble reactive phosphorus, SRP), most species fed on P-enriched diets and P excretion rates were high across species. In low-P conditions (3 microg/L SRP), aquatic food resources were depleted in P, and species with higher body P content showed low rates of P recycling. However, fishes that were subsidized by terrestrial inputs were decoupled from aquatic P availability and therefore excreted P at disproportionately high rates. One of these species, Astyanax aeneus (Characidae), represented 12% of the total population and 18% of the total biomass of the fish assemblage in our focal low-P study stream but had P excretion rates > 10-fold higher than other abundant fishes. As a result, we estimated that P excretion by A. aeneus accounted for 90% of the P recycled by this fish assemblage and also supplied approximately 90% of the stream P demand in this P-limited ecosystem. Nitrogen excretion rates showed little variation among species, and the contribution of a given species to ecosystem N recycling was largely dependent upon the total biomass of that species. Because of the high variability in P excretion rates among fish species, ecosystem-level P recycling could be particularly sensitive to changes in fish community structure in P-limited systems.     

Sponge-feeding fishes of the West Indies

In an analysis of the stomach contents of 212 species of West Indian reef and inshore fishes, sponge remains were found in 21 species. In eleven of these, sponges comprised 6% or more of the stomach contents; it is assumed that these fishes feed intentionally on sponges. Sponges comprise over 95% of the food of angelfishes of the genus Holacanthus, over 70% of the food of species of the related genus Pomacanthus, and more than 85% of the food of the filefish, Cantherhines macrocerus. Lesser quantities of sponges are ingested by the remaining fish species. Fishes that feed on sponges belong to highly specialized teleost families, suggesting that this habit has evolved in geologically late time. The small number of fish species that concentrate on sponges as food suggests that the defensive characters of sponges—mineralized sclerites, noxious chemical substances, and tough fibrous components—are highly effective in discouraging predation. The two sponges most frequently eaten by fishes have a low percentage of siliceous spicules relative to organic matter, but among the 20 next most frequently consumed species no striking correlation occurs with respect to spicule content. Color and form of the sponge show no special correlation with frequency of occurrence in fish stomachs. Three species of fishes appear to concentrate on one species of sponge, but in these cases over 60% of the food taken consists of a variety of other organisms. Those fishes, more than half of whose diet consists of sponges, tend to sample a wide variety of species. No strong evidence is provided by our data that fish predation is a significant factor in limiting sponge distribution in the West Indian region.     

Topology of Extinction and Endangerment of Native Fishes in the Pacific Northwest and California (U.S.A.)

Recent studies have provided a broad data base on extinction and endangerment of species, subspecies, and distinct populations of inland fishes in western North America. Development of a synoptic, regional-scale image of extinction and risk of extinction is complicated by the small size and linear distribution of fluvial aquatic habitats and by interspecific variation in areal extent of populations. I developed a regional map of extinction-risk isopleths based on the number of extinct and persistently declining species in drainage basins of the Pacific Northwest and California. This topological synthesis is useful for delineating and monitoring areas of historic and ongoing loss of aquatic biodiversity, and for relating losses to patterns of land use and habitat modification, climate hydrology, and geomorphology. From an ecological perspective, endangerment of numerous indigenous populations of seven widely distributed species of anadromous salmonids in this region is as important as the more local, diffuse effects of declines in more than 60 endemic, nonanadromous species and subspecies. The simultaneous decline of numerous taxa in basins not afflicted with dams or diversions suggests that cumulative damage to aquatic habitats caused by logging, grazing, urbanization, and other land uses plays a major role in icthyofaunal impoverishment.     

Relative influence of environmental factors and fishing on coral reef fish assemblages

Understanding whether assemblages of species respond more strongly to bottom-up (availability of trophic resources or habitats) or top-down (predation pressure) processes is important for effective management of resources and ecosystems. We determined the relative influence of environmental factors and predation by humans in shaping the density, biomass, and species richness of 4 medium-bodied (10–40 cm total length [TL]) coral reef fish groups targeted by fishers (mesopredators, planktivores, grazer and detritivores, and scrapers) and the density of 2 groups not targeted by fishers (invertivores, small fish ≤10 cm TL) in the central Philippines. Boosted regression trees were used to model the response of each fish group to 21 predictor variables: 13 habitat variables, 5 island variables, and 3 fishing variables (no-take marine reserve [NTMR] presence or absence, NTMR size, and NTMR age). Targeted and nontargeted fish groups responded most strongly to habitat variables, then island variables. Fishing (NTMR) variables generally had less influence on fish groups. Of the habitat variables, live hard coral cover, structural complexity or habitat complexity index, and depth had the greatest effects on density, biomass, and species richness of targeted fish groups and on the density of nontargeted fishes. Of the island variables, proximity to the nearest river and island elevation had the most influence on fish groups. The NTMRs affected only fishes targeted by fishers; NTMR size positively correlated with density, biomass, and species richness of targeted fishes, particularly mesopredatory, and grazing and detritivorous fishes. Importantly, NTMRs as small as 15 ha positively affected medium-bodied fishes. This finding provides reassurance for regions that have invested in small-scale community-managed NTMRs. However, management strategies that integrate sound coastal land-use practices to conserve adjacent reef fish habitat, strategic NTMR placement, and establishment of larger NTMRs will be crucial for maintaining biodiversity and fisheries.