Wilderness Fish Stocking: History and Perspective

The stocking of trout in wilderness lakes of the western United States began in the 1800s. This practice was followed for nearly a century with the singular goal of creating and enhancing sport fishing and without any consideration of its ecological ramifications. Following the advent of a new environmental awareness in the 1960s, and thanks to new research that revealed negative impacts on the biota attributable to introduced fishes, traditional fish-stocking practices came under question first at federal land management agencies and later at their counterparts within the states. The highly utilitarian ethic that drove resource management until well into the 1960s was gradually replaced by one that acknowledges the value of all life forms and their ecological complexity, a view currently supported even by many anglers. The necessity for wilderness fish stocking is now the subject of widespread debate, especially in view of changing social values and priorities. Options for future generations cannot be preserved if introductions continue to erode the biodiversity of mountain lake ecosystems. Received 28 March 2000; accepted 30 May 2000.     

Local and Landscape Effects of Introduced Trout on Amphibians in Historically Fishless Watersheds

Introduced trout have often been implicated in the decline of high-mountain amphibian populations, but few studies have attempted to understand whether fish stocking also influences the distribution and abundance of amphibians throughout entire mountain basins, including the remaining fishless lakes. We examined this relationship using the relative abundance of long-toed salamanders (Ambystoma macrodactylum) and Columbia spotted frogs (Rana luteiventris) in fish-containing and fishless lentic sites in basins with varying levels of historic fish stocking. All lentic waters were surveyed for fish and amphibians in 11 high-elevation basins in the Frank Church-River of No Return Wilderness, Idaho, between 1994 and 1999. We found introduced trout (Oncorhynchus clarki, O. mykiss, O. m. aguabonita) in 43 of the 101 sites, representing 90% of the total surface area of lentic water bodies available. At the scale of individual water bodies, after accounting for differences in habitat characteristics between fish-containing and fishless sites, the abundance of amphibians at all life stages was significantly lower in lakes with fish. At the basin scale, densities of overwintering life stages of amphibians were lower in the fishless sites of basins where more habitat was occupied by trout. Our results suggest that many of the remaining fishless habitats are too shallow to provide suitable breeding or overwintering sites for these amphibians and that current trout distributions may eventually result in the extirpation of amphibian populations from entire landscapes, including sites that remain in a fishless condition. Received 28 March 2000;Accepted 2 January 2001.     

The Effects of Stocking and Removal of a Nonnative Salmonid on the Plankton of an Alpine Lake

Bighorn Lake, a fishless alpine lake, was stocked with nonnative brook trout, Salvelinus fontinalis, in 1965 and 1966. The newly introduced trout rapidly eliminated the large crustaceans Hesperodiaptomus arcticus and Daphnia middendorffiana from the plankton. In July 1997, we began to remove the fish using gill nets. The population comprised 261 fish that averaged 214 g in wet weight and 273 mm in fork length. Thereafter, zooplankton abundance increased within weeks. Early increases were caused by the maturation of Diacyclops bicuspidatus, few of which reached copepodid stages before the removal of the fish because of fish predation. Daphnia middendorffiana, absent when fish were present, reappeared in 1998. Hesperodiaptomus arcticus, which had been eliminated by the stocked fish, did not return. The proportion of large zooplankton increased after fish removal, but their overall biomass did not change. Algal biomass was low and variable throughout the 1990s and correlated with water temperature but not with nutrient concentrations or grazer densities. Diatoms were the most abundant algal taxon in the lake, followed by Dinophyceae. Chrysophyceans and cryptophyceans were eliminated after the fish were removed. Chlorophyll a concentrations were unaffected. Gill netting is a viable fish eradication technique for smaller (less than 10 ha), shallow (less than 10 m deep) lakes that lack habitable inflows and outflows or other sensitive species. Further work is required to define appropriate removal methods for larger lakes and watersheds. Received 30 May 2000; Accepted 14 November 2000.     

Alteration of Nutrient Cycles and Algal Production Resulting from Fish Introductions intoMountain Lakes

The introduction of salmonid fishes into naturally fishless lakes represents one of the most prevalent environmental modifications of aquatic ecosystems in western North America. Introduced fish may alter lake nutrient cycles and primary production, but the magnitude and variation of these effects have not been fully explored. We used bioenergetics modeling to estimate the contributions of stocked trout to phosphorus (P) cycles across a wide range of fish densities in lakes of the Sierra Nevada, California. We also assessed the larger effects of fish-induced changes in phosphorus cycling on primary production using paleolimnological analyses from lakes in the southern Canadian Rockies. Our analyses showed that total P recycling by fish was independent of fish density but positively related to fish biomass in the Sierra Nevada. In lakes with fish populations maintained by continued stocking, fish recycled P at over twice the rate of those in lakes where introduced fish populations are maintained by natural reproduction and stocking has been discontinued. We estimate that P regeneration by introduced fishes is approximately equivalent to atmospheric P deposition to these lakes. Paleolimnological analyses indicated that algal production increased substantially following trout introductions to Rocky Mountain lakes and was maintained for the duration of fish presence. The results of our modeling and paleolimnological analyses indicate that introduced trout fundamentally alter nutrient cycles and stimulate primary production by accessing benthic P sources that are not normally available to pelagic communities in oligotrophic mountain lakes. These effects pose a difficult challenge for managers charged with balancing the demand for recreational fisheries with the need to maintain natural ecosystem processes. Received 28 March 2000; accepted 4 January 2001.     

The Humphead Wrasse,Cheilinus Undulatus: Synopsis of a Threatened and Poorly Known Giant Coral Reef Fish

The humphead wrasse, Cheilinus undulatus, is the largest living member of the family Labridae, with a maximum size exceeding 2 m and 190 kg. Its geographic range covers much of the Indo-Pacific. The species is not common, recorded maximum adult densities rarely exceeding 20 fish/10,000 m². Small individuals are typically associated with high coral cover; larger fish are found mainly on outer or deep reefs, steep slopes and passes, singly or in small groups and seagrasses. However, for reproduction the species forms small spawning aggregations of tens to more than one hundred fish. The diet of the humphead wrasse includes large invertebrates and small fishes. The species attains at least 30 years and reaches sexual maturation at about 35–50 cm total length and <5 years of age. Most small adults are female while mainly males exceed 1 m and there is evidence of female to male sex change. The humphead wrasse is of considerable cultural value in some Pacific countries and is among the most prized in the live reef food fish export trade, for which it is often taken in its juvenile size range, either directly for sale or, increasingly, for grow-out to market size. It is also marketed chilled. The species is particularly sensitive to fishing pressure. In most fished areas, density and body size have dropped substantially. It appears to be particularly heavily targeted and depleted in SE Asia and in some places faces extirpation. The humphead wrasse is often taken by night spearfishing and by cyanide, with protection typically weak or non-existent, despite regulations and by a vulnerable assessment on the 1996 IUCN Red List. The humphead wrasse has not been reared successfully in hatcheries. Other giant reef fish share many similar problems and detailed study of the humphead wrasse contributes to a better understanding and conservation of all such species. This review examines and evaluates published and gray literature, original unpublished research and correspondence with almost 50 knowledgeable workers. It examines the value of such sources for quickly, but adequately, assessing the conservation and management status and key data gaps in species that are little known, vulnerable, difficult and expensive to study and may require urgent management or conservation action.     

The Health and Ecological Impacts of Organochlorine Pesticide Pollution in China: Bioaccumulation of Organochlorine Pesticides in Human and Fish Fats

The levels of organochlorine pesticides (OCPs) in the environment and foods have declined significantly in China since 1983, the year when their use in agriculture was officially banned. The levels today of these contaminants in soil, water, and agricultural products are well below 50 μg/kg in many parts of China. Yet in spite of such a decline, the current levels of pollution still pose a significant health risk to many people in China because OCPs are highly persistent and bioaccumulative substances. This preliminary study was conducted to monitor the levels of hexachlorocyclohexane (HCH) and dichloro-diphenyl-trichloroethane (DDT) in human and fish fats from southeast China in an effort to corroborate the above health concern. The data reconfirmed that pollution by HCH and DDT, which are the major components of OCPs, is a serious ecological problem in the study region, and likely in other parts of China as well. The HCH contents in the human samples were between 0.25 and 2.20 mg/kg, with an average of 0.90 mg/kg. The DDT contents in these human samples were much higher, between 0.54 and 9.22 mg/kg with an average of 3.50 mg/kg. The major isomers found in the human samples were β-HCH and p, p′-DDE, representing 94.9 to 99.5% of total HCH and 72.3 to 96.7% of total DDT, respectively. The HCH and DDT content in the grass carp samples averaged 0.03 and 0.67 mg/kg, respectively. The levels of bioaccumulation reflected in these human and fish samples were considered substantial, particularly when residents in the study region continue to be exposed to the OCPs remaining so persistently in their environment. It is therefore important for the health authorities to launch a large-scale investigation into the potential health and ecological impacts of OCP pollution in China. The data also suggested that the current national standards might need to be lowered for the levels of OCPs in the environment in China.     

Cascading Trophic Interactions from Fish to Bacteria and Nutrients after Reduced Sewage Loading: An 18-Year Study of a Shallow Hypertrophic Lake

The effects of major reductions in organic matter, total phosphorus (TP), and total nitrogen (TN) loading on the chemical environment, trophic structure, and dynamics of the hypertrophic, shallow Lake Søbygård were followed for 18 years. After the reduction in organic matter loading in 1976, the lake initially shifted from a summer clear-water state, most likely reflecting high grazing pressure by large Daphniaspecies, to a turbid state with extremely high summer mean chlorophyll a (up to 1400 μg L^{? 1}), high pH (up to 10.2), and low zooplankton grazing. Subsequently, a more variable state with periodically high grazing rates on phytoplankton and bacteria was established. Changes in zooplankton abundance and grazing could be attributed to variations in cyprinid abundance due to a fish kill (probably as a consequence of oxygen depletion) and pH-induced variations in fish recruitment and fry survival. The results suggest strong cascading effects of fish on the abundance and size of zooplankton and phytoplankton and on phytoplankton production. A comparatively weak cascading effect on ciliates and bacterioplankton is suggested. Due to high internal loading, only minor changes were observed in lake-water TP after a reduction in external TP loading of approximately 80% in 1982; net retention of TP was still negative 13 years after the loading reduction, despite a short hydraulic retention time of a few weeks. TN, however, decreased proportionally to the TN-loading reduction in 1987, suggesting a fast N equilibration. Only minor improvement in the environmental state of the lake has been observed. We suggest that another decade will be required before the lake is in equilibrium with present external P loading.     

Residues of Aliphatic and Polycyclic Aromatic Hydrocarbons in Some Fish Species of Lake Temsah,Ismailia, Egypt: An Analytical Search for Hydrocarbon Sources and Exposure Bioindicators

Residues of aliphatic and polycyclic aromatic hydrocarbons (PAHs) were monitored in some fish species collected from Temsah Lake, near Ismailia, Egypt. Fish were selected to represent different feeding habits and ecological niches in the lake's ecosystem. Fish samples were extracted using organic solvents, and residues of aliphatic and PAHs were separated using column chromatography and detected using gas liquid chromatography. Fish species were Clupea sirm, Mugil sehli, Mugil capito, Morone labrax, and Sciasna sp. Clupea sirm, a surface feeder fish had the highest concentration of aliphatic hydrocarbons, 320 ± 54 ng g^?1, while Morone labrax, a predatory fish that live in the water column, had the highest concentration of PAHs, 315.87 ± 46 ng g^?1. Even-number aliphatic hydrocarbons were more frequently detected in all fish species in comparison to odd-number aliphatic hydrocarbons, suggesting a petrogenic origin of these compounds. Meanwhile, the pattern of PAHs detected in the present study suggested that they originate from atmospheric deposition rather than land-based runoff. Morone labrax fish and Clupea sirm fish were the most suitable candidate bioindicators of exposure to aliphatic hydrocarbons and PAHs through fish consumption of the five fish species examined in this study.     

Biomanipulation as an Application of Food-Chain Theory: Constraints, Synthesis, and Recommendations for Temperate Lakes

The aim of this review is to identify problems, find general patterns, and extract recommendations for successful biomanipulation. An important conclusion is that the pelagic food chain from fish to algae may not be the only process affected by a biomanipulation. Instead, this process should be viewed as the “trigger” for secondary processes, such as establishment of submerged macrophytes, reduced internal loading of nutrients, and reduced resuspension of particles from the sediment. However, fish reduction also leads to a high recruitment of young-of-the-year (YOY) fish, which feed extensively on zooplankton. This expansion of YOY the first years after fish reduction is probably a major reason for less successful biomanipulations. Recent, large-scale biomanipulations have made it possible to update earlier recommendations regarding when, where, and how biomanipulation should be performed. More applicable recommendations include (1) the reduction in the biomass of planktivorous fish should be 75% or more; (2) the fish reduction should be performed efficiently and rapidly (within 1–3 years); (3) efforts should be made to reduce the number of benthic feeding fish; (4) the recruitment of YOY fish should be reduced; (5) the conditions for establishment of submerged macrophytes should be improved; and (6) the external input of nutrients (phosphorus and nitrogen) should be reduced as much as possible before the biomanipulation. Recent biomanipulations have shown that, correctly performed, the method also achieves results in large, relatively deep and eutrophic lakes, at least in a 5-year perspective. Although repeated measures may be necessary, the general conclusion is that biomanipulation is not only possible, but also a relatively inexpensive and attractive method for management of eutrophic lakes, and in particular as a follow-up measure to reduced nutrient load. Received 14 April 1998; accepted 31 August 1998     

The Utility of Carbon and Nitrogen Isotope Analyses to Trace Contributions from Fish Farms to the Receiving Communities of Freshwater Lakes: a Pilot Study in Esthwaite Water,UK

A pilot study was conducted to assess the potential for stable isotope analyses to reveal the fate of waste pelleted food material from fish farms in freshwater food webs. Esthwaite Water (Cumbria, UK) was selected as the study site, as it hosts an established salmonid farm, and a wealth of complementary limnological data exists. Salmonid pellet feed consists of primarily marine-derived material and thus exhibits carbon and nitrogen stable isotopic compositions distinct to most freshwater organic material. Comparison of the isotopic ratios of organisms at the cage site with an unaffected control site, supports incorporation of pellet-derived material to the diet of planktonic and benthic communities. Moreover, after allowing for a number of trophic transfers, stable isotope analyses revealed the predatory cladoceran Leptodora kindti also utilised pellet material, while roach were probably short-circuiting the food chain by directly consuming particulate pellet material, as well as via ingestion of their zooplankton prey. Isotope data substituted into a simple two-source mixing model suggested that approximately 65% of Daphnia, and >80% of roach body carbon may be derived from pellet material in the plankton, and that chironomid larvae may incorporate >50% in the sediment environs. However, contributions calculated from both ¹³C and ¹⁵N values were inconsistent, which may simply be due to the constraints of the model and parameters used, but may also reflect different routing of isotopes from the original pellet source, via soluble or particulate routes.     

Original Articles: Plant Attribute Diversity, Resilience, and Ecosystem Function: The Nature and Significance of Dominant and Minor Species

This study tested an hypothesis concerning patterns in species abundance in ecological communities. Why do the majority of species occur in low abundance, with just a few making up the bulk of the biomass? We propose that many of the minor species are analogues of the dominants in terms of the ecosystem functions they perform, but differ in terms of their capabilities to respond to environmental stresses and disturbance. They thereby confer resilience on the community with respect to ecosystem function. Under changing conditions, ecosystem function is maintained when dominants decline or are lost because functionally equivalent minor species are able to substitute for them. We have tested this hypothesis with respect to ecosystem functions relating to global change. In particular, we identified five plant functional attributes—height, biomass, specific leaf area, longevity, and leaf litter quality—that determine carbon and water fluxes. We assigned values for these functional attributes to each of the graminoid species in a lightly grazed site and in a heavily grazed site in an Australian rangeland. Our resilience proposition was cast in the form of three specific hypotheses in relation to expected similarities and dissimilarities between dominant and minor species, within and between sites. Functional similarity—or ecological distance—was determined as the euclidean distance between species in functional attribute space. The analyses provide evidence in support of the resilience hypothesis. Specifically, within the lightly grazed community, dominant species were functionally more dissimilar to one another, and functionally similar species more widely separated in abundance rank, than would be expected on the basis of average ecological distances in the community. Between communities, depending on the test used, two of three, or three of four minor species in the lightly grazed community that were predicted to increase in the heavily grazed community did in fact do so. Although there has been emphasis on the importance of functional diversity in supporting the flow of ecosystem goods and services, the evidence from this study indicates that functional similarity (between dominant and minor species, and among minor species) may be equally important in ensuring persistence (resilience) of ecosystem function under changing environmental conditions.     

The effect of chlorpromazine on SCE frequency in human chromosomes: An in vitro and in vivo study

Schizophrenic patients who were receiving, or who had received chlorpromazine showed SCE levels similar to those in a normal control population. Of 8 normal individuals whose lymphocytes were exposed in vitro to chlorpromazine (0.05–2.00 μg/ml) for two cell cycles, 4 showed a significant increase in SCE, 3 showed no increase and 1 a decrease compared with untreated lymphocytes. Lymphocytes from a further 8 donors treated with 2.0 μg/ml chlorpromazine prior to mitogen stimulation (G₀ lymphocytes) showed a similar SCE response. Only 3 of the 8 donors showed a significant increase in SCEs over the baseline level. When proliferating lymphocytes were exposed to chlorpromazine 38 h after culture initiation and prior to the addition of BrdUrd to the culture medium, metaphase chromosomes from only 3 of the 8 individuals studied showed increased levels of exchange. These results indicate that chlorpromazine can induce SCEs in vitro but that there is considerable variation in SCE response among individuals. Furthermore, our data emphasises the importance of using more than 1 or 2 donors when analysing SCE response in human chromosomes.     

Milli-calpain from Sea Bass (Dicentrarchus labrax) White Muscle: Purification, Characterization of Its Activity and Activation In Vitro

A calcium-activated neutral cysteine protease was purified to homogeneity from Dicentrarchus labrax white muscle using three steps: hydrophobic interaction, anion exchange, and gel filtration chromatographies. The purified enzyme showed a native molecular weight of 124 kDa with an oligomeric structure (large subunit of 80 kDa and small subunit of 24 kDa). It has been classified as a milli-calpain from its calcium sensitivity. Activity was maximal at pH 7.0, 24°C in Tris buffer without NaCl as determined by means of a two-level experimental design and response surface methodology. Sea bass calpain is neither glycosylated nor phosphorylated and shared some common cleavage specificities and activation and autolysis mechanisms with other typical mammalian or invertebrates calpains. Calcium-induced activation and autolysis of calpain has been characterized together with the effect of the strontium cation acting as a calcium analog. On the basis of its in vitro properties, the contribution of the sea bass milli-calpain to the process of postmortem deterioration of fish muscle is discussed, even though further information such as in vivo regulation or in vitro effects on myofibrils is required. Received March 1, 2001; accepted July 9, 2001.     

The role of subcellular organelles in hormone secretion : The interactions of calcium, vitamin A, vinblastine, and cytochalasin B in PTH secretion

To determine the role of subcellular organelles in hormone secretion, we studied the interaction of low calcium concentration (low Ca), retinol (vitamin A, vit A), vinblastine (VB), and cytochalasin B (CB) in parathyroid hormone (PTH) secretion. Bovine parathyroid tissue pieces were incubated in media containing the above agents. Vit A stimulated PTH release to a mean of 170% of control. This effect of vit A was diminished when tissues were simultaneously stimulated with low Ca and, furthermore, absent when tissues were pre-incubated in low Ca.VB had no effect on low Ca-stimulated secretion, but did inhibit vit A-induced secretion in the presence of low Ca.CB stimulated PTH secretion to a mean of 150% of control during the second and third hours of incubation. CB had at least an additive effect with low Ca in stimulating PTH secretion, with a more prompt and greater response than seen in normal calcium. VB did not inhibit the acute effect of CB on secretion in normal calcium media, but did inhibit CB-induced secretion during the third hour of incubation.None of the agents stimulated the release of lysosomal cathepsin D, and vit A and CB did not stimulate the release of LDH.Our results suggest that; (1) vit A and low Ca stimulate PTH secretion through a common pathway involving the cell membrane; (2) CB stimulates PTH secretion through a separate effect on the cell membrane or submembrane microfilaments, which normally retards secretion of PTH; and (3) microtubular proteins may facilitate basal secretion of PTH, but are not involved in low Ca-stimulated secretion of PTH.     

The extracellular pollen coat in members of the Brassicaceae: composition, biosynthesis, and functions in pollination

Summary. I have used cellular and molecular genetic and bioinformatic approaches to characterise the components of the pollen coat in plants of the family Brassicaceae, including Arabidopsis thaliana and several brassicas including Brassica napus, B. oleracea, and B. rapa. The pollen coat in these species is mostly made up of a unique mixture of lipids that is highly enriched in acylated compounds, such as sterol esters and phospholipids. These acyl lipids are characterised by an unusually high degree of saturation. The fatty acids typically contain 70–90% saturated acyl residues such as myristate, palmitate, and stearate. The major sterol components of the pollen coat are saturated fatty acyl esters of stigmasterol, campesterol, and campestdienol. In addition to lipids, the second major component of the pollen coat is a specific group of proteins that is dominated by a family of proteins that we term pollenins. Although pollenins are by far the major protein components of the pollen coat of members of the Brassicaceae, proteomic analysis reveals that there are several additional protein components, including lipases, protein kinases, a pectin esterase, and a caleosin. The biosynthesis of these lipids and proteins and their significance for overall pollen function are reviewed and discussed. Correspondence and reprints: Biotechnology Unit, School of Applied Sciences, University of Glamorgan, Pontypridd CF37 1DL, Wales, United Kingdom.     

The Importance of Iron,Calcium and Free Radicals in Reperfusion Injury: An Overview of Studies in Ischaemic Rabbit Kidneys

An overview of a series of experiments attempting to link iron and calcium redistribution and release of free fatty acids with falls in pH and adenine nucleotide levels during cold storage of rabbit kidneys is presented. The data reviewed strongly suggest that these events are inextricably linked to subsequent reperfusion injury. Circumstantial evidence incriminating iron was provided by experiments showing that iron chelation decreased reperfusion injury after warm (WI) and cold ischaemia (CI) in rat skin flap and rabbit kidney models. Evidence for a role for calcium was provided when it was found that a calcium channel blocking agent added to the saline flush solution before storage inhibited lipid peroxidation, whereas chemicals which caused release or influx of calcium into the cell exacerbated oxidative damage. Additional involvement of breakdown products of adenine nucleotides was suggested by the protection from lipid peroxidation afforded by allopurinol. Involvement of calcium-activated phospholipase A, was strongly suggested by increases In free fatty acids during cold storage and both this increase and lipid peroxidation were inhibited by addition of dibucaine to the storage solution.     

The lambda head-tail joining reaction: purification, properties and structure of biologically active heads and tails

Procedures were developed to obtain biologically active lambda heads and tails at high purity with 20 to 40% recovery. Free heads, free tails and phage particles differ markedly in stability. Phage are stable in solutions containing Mg²⁺ but tails are not. The protein subunits which form the shaft of the tail dissociate in the presence of Mg²⁺ and form multisubunit spherical structures. EDTA protects free tails against inactivation but disrupts heads and phage particles. The four carbon diamine, putrescine, stabilizes heads against inactivation; the three and five carbon diamines are less effective. Electron micrographs reveal a new “knob” structure at the distal end of the tail fiber of phage and of free tails. Tails released from EDTA-disrupted phage possess a “head-tail connector”, a structure not present on the tail before its joining with a head.