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  • Articles  (44)
  • fish
  • Springer  (44)
  • 1995-1999  (44)
  • 1997  (44)
  • 1
    Electronic Resource
    Electronic Resource
    Are Tropical Herbivores More Resistant Than Temperate Herbivores to Seaweed Chemical Defenses? Diterpenoid Metobolites from Dictyota acutiloba as Feeding Deterrents for Tropical Versus Temperate Fishes and Urchins (1997)
    Springer
    Journal of chemical ecology 23 (1997), S. 289-302 
    Details
    ISSN: 1573-1561
    Keywords: Acutilol diterpenes ; biogeography ; chemical defenses ; Dictyota ; diffuse coevolution ; fish ; plant–herbivore interactions ; sea urchin ; secondary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Because herbivory is more intense in the tropics, tropical seaweeds may be better defended against herbivory than are temperate seaweeds. A “diffuse” coevolutionary corollary to this hypothesis is that tropical herbivores should be more resistant to seaweed defenses than temperate herbivores because tropical herbivores more commonly encounter heavily defended seaweeds. We begin to test the latter prediction using three newly discovered diterpenoid secondary metabolites from the tropical brown alga Dictyota acutiloba. We tested the feeding deterrent properties of these compounds against common herbivorous fishes and sea urchins from warm-temperate North Carolina versus tropical Guam using standardized laboratory feeding assays. The temperate herbivores were deterred by lower concentrations of secondary metabolites than the tropical herbivores. In no case was a tropical herbivore more deterred by a compound than a temperate herbivore, suggesting that temperate herbivores may be more strongly affected by seaweed chemical defenses. Feeding by the temperate pinfish Lagodon rhomboides was significantly reduced by two of the three diterpenes at a concentration that was only 13–18% of the natural concentration found in the alga. Feeding by four species of tropical fishes (two parrotfishes and two surgeonfishes) was unaffected by metabolite concentrations that deterred the temperate fish. At 100% of natural concentrations, only one of the three compounds deterred the two parrotfishes, and none of the three compounds deterred the surgeonfishes. Contrasts between the temperate sea urchin Arbacia punctulata and the tropical sea urchin Diadema savignyi showed a similar pattern; low concentrations of acutilol A acetate strongly deterred the temperate, but not the tropical, urchin. Tropical herbivores appear more resistant than temperate herbivores to seaweed chemical defenses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:JOEC.0000006360.36833.13
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  • 2
    Electronic Resource
    Electronic Resource
    WHOLE-CATCHMENT LIMING AT TJØNNSTROND, NORWAY: AN 11-YEAR RECORD (1997)
    Springer
    Water, air & soil pollution 94 (1997), S. 163-180 
    Details
    ISSN: 1573-2932
    Keywords: acid deposition ; liming ; catchment ; lake ; water chemistry ; fish ; soil ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In June 1983 a whole-catchment liming experiment was conducted at Tjønnstrond, southernmost Norway, to test the utility of terrestrial liming as a technique to restore fish populations in remote lakes with short water-retention times. Tjønnstrond consists of 2 small ponds of 3.0 and 1.5 ha in area which drain a 25-ha catchment. The area is located at about 650–700 meters above sea-level in sparse and unproductive forests of spruce, pine and birch with abundant peatlands. A dose of 3 ton/ha of powdered limestone were spread by helicopter to the terrestrial area. No limestone was added to the ponds themselves. The ponds were subsequently stocked with brown and brook trout. Liming caused large and immediate changes in surface water chemistry; pH increased from 4.5 to 7.0, Ca increased from 40 to 200 μeq/L, ANC increased from –30 to +70 μeq/L, and reactive-Al decreased from about 10 to 3 μmol/L. During the subsequent 11 years the chemical composition of runoff has decreased gradually back towards the acidic pre-treatment situation. The major trends in concentrations of runoff Ca, ANC, pH, Al and NO3 in runoff are all well simulated by the acidification model MAGIC. Neither the measured data nor the MAGIC simulations indicate significant changes in any other major ion as a result of liming. The soils at Tjønnstrond in 1992 contained significantly higher amounts of exchangeable Ca relative to those at the untreated reference catchment Storgama. In 1992 about 75% of the added Ca remains in the soil as exchangeable Ca, 15% has been lost in runoff, and 10% is unaccounted for. The whole-catchment liming experiment at Tjønnstrond clearly demonstrates that this liming technique produces a long-term stable and favourable water quality for fish. Brown trout in both ponds in 1994 have good condition factors, which indicate that the fish are not stressed by marginal water quality due to re-acidification. The water quality is still adequate after 11 years and 〉20 water renewals. Concentrations of H+ and inorganic Al have gradually increased and approach levels toxic to trout, but the toxicity of these are offset by the continued elevated Ca concentrations. Reduced sulphate deposition during the last 4 years (1990–94) has also helped to slow and even reverse the rate of reacidification. The experiment at Tjønnstrond demonstrates that for this type of upland, remote terrain typical of large areas of southern Norway, terrestrial liming offers a suitable mitigation technique for treating acidified surface waters with short retention times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026442821924
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  • 3
    Electronic Resource
    Electronic Resource
    Structural and functional impairment of the hypothalamo- pituitary-interrenal axis in fish exposed to bleached kraft mill effluent in the St Maurice River, Quebec (1997)
    Springer
    Ecotoxicology 6 (1997), S. 1-12 
    Details
    ISSN: 1573-3017
    Keywords: cortisol ; BKME ; fish ; interrenal ; pituitary ; morphol ogy ; acute stress ; endocrine dysfunction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The effects of bleached kraft mill effluent (BKME) on blood cortisol levels and the morphology of the pituitary-interrenal axis were investigated in two species of teleost fish, the northern pike, Esox lucius, and the yellow perch, Perca flavescens, sampled upstream and downstream from a pulp and paper mill on the St Maurice River, Quebec. Fish were acutely stressed by a standardized capture and sampling protocol at both sites, and their ability to elevate blood cortisol levels in response to the capture stress was compared. Blood cortisol levels in fish from the upstream site (〉100 ng/ml plasma) were higher than the levels in fish from the BKME site, and the pituitary corticotropes and the interrenal steroidogenic cells of the upstream fish were larger and had larger nuclei compared with cells from the downstream fish. The low blood cortisol levels in fish exposed to BKME were correlated to cellular atrophy within the hypothalamo-pituitary-interrenal (HPI) axis. The reduced ability to elevate blood cortisol in response to an acute stress may be an endocrine dysfunction occuring in fish chronically exposed to chemical stressors in their environment
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018699405158
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  • 4
    Electronic Resource
    Electronic Resource
    Risk from genetically engineered and modified marine fish (1997)
    Springer
    Transgenic research 6 (1997), S. 59-67 
    Details
    ISSN: 1573-9368
    Keywords: Sparus aurata ; transgenic ; ecologicalrisk ; release ; genetic modification ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In support of the emerging industries of warmwater marine fish mariculture, genetic engineering and classical genetic improvement programmes have been initiated for a variety of exclusively marine fish. These programmes have the potential to perturb allele and genotype frequencies, or introduce novel alleles and genes into conspecific wild populations. Despite concerns to the contrary, the following hypothesis remains to be falsified: ‘laboratory induced allele frequency/genotype changes and novel alleles or genes have a negligible probability of being selectively favoured in wild populations under natural selection, and accordingly, without sustained large scale releases, have little potential for ecological impact’
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018457100476
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  • 5
    Electronic Resource
    Electronic Resource
    Food-web manipulation in a small, eutrophic Lake Wirbel, Poland: the effect of replacement of key predators on epiphytic fauna (1997)
    Springer
    Hydrobiologia 342-343 (1997), S. 377-381 
    Details
    ISSN: 1573-5117
    Keywords: key-predator replacement ; fish ; invertebrate carnivores ; epiphytic fauna ; Chironomidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of fish removal on the invertebrate fauna associatedwith Stratiotes aloides was studied in a shallow, eutrophiclake. The biomass of invertebrate predators was approximately 2.5times higher in the invertebrate-dominated year (1992) than in thefish-dominated year (1991), while the density of non-predatoryinvertebrates in 1991 was ca half that in theinvertebrate-dominated year. The decrease was due to a sharp fallin the density of epiphytic chironomids, with the density ofplant-mining chironomids being far less affected. Marked declinesin the density of non-predatory invertebrates in theinvertebrate-dominated year were most probably caused byinvertebrate predators. Once freed from suppression induced byfish, invertebrate predators were able to control the density ofepiphytic prey more effectively than fish.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017095508464
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  • 6
    Electronic Resource
    Electronic Resource
    Ecomorphological diet predictions: an assessment using inland silverside (Menidia beryllina) and longear sunfish (Lepomis megalotis) from Lake Texoma (1997)
    Springer
    Hydrobiologia 350 (1997), S. 87-98 
    Details
    ISSN: 1573-5117
    Keywords: ecomorphology ; trophic ecology ; physiology ; diet ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The functions of an organism‘s morphological structures indicatethe organism‘s potential resource use (fundamental niche). Whilethis information often is also used to predict differences inactual resource use (realized niche) among individuals or species,such predictions may not be accurate because the maximum abilitiesmay not be useful to the organism under specific conditions or inspecific environments. We investigated the importance of sixpreviously studied morphologically based performanceabilities/constraints in structuring the diet of Menidiaberyllina (inland silverside) and Lepomis megalotis (longearsunfish) in Lake Texoma, a reservoir in the Red River basin(Oklahoma-Texas, USA). Of the six morphological characteristicsmeasured (number of gill rakers, length of gill rakers, spacebetween gill rakers, eye lens diameter, mouth size, mouthprotrusibility), only one characteristic for M. beryllina(mouth size) and three for L. megalotis (space betweenrakers, mouth size, and raker length) correlated with the gutcontents as predicted by previous functional morphology studies.This indicates that caution should be exercised when makinguntested predictions about the ecology of an organism based on itsfunctional morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003075529973
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of zebra mussels on food webs: interactions with juvenile bluegill and water residence time (1997)
    Springer
    Hydrobiologia 354 (1997), S. 141-150 
    Details
    ISSN: 1573-5117
    Keywords: Dreissena ; mesocosm ; seston ; fish ; food web ; manipulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We evaluated how water residence time mediated the impact of zebramussels Dreissena polymorpha and bluegill sunfish Lepomis macrochirus on experimental food webs established in1100-l outdoor mesocosms. Water residence time was manipulated asa surrogate for seston resupply – a critical variable affectinggrowth and survival of suspension-feeding invertebrates. We used a2×2×2 factorial experimental design witheight treatment combinations (3 replicates/treatment) including thepresence or absence of Dreissena (2000 per m2), juvenilebluegill (40 per mesocosm), and short (1100 l per d) or long (220 lper d) water residence time. Measures of seston concentration(chlorophyll a, turbidity and suspended solids) were greaterin the short- compared to long water-residence mesocosms, butintermediate in short water-residence mesocosms containing Dreissena. Abundance of rotifers (Keratella and Polyarthra) was reduced in Dreissena mesocosms and elevatedin short residence time mesocosms. Cladocera abundance, in general,was unaffected by the presence of Dreissena; densities werehigher in short-residence time mesocosms, and reduced in thepresence of Lepomis. The growth of juvenile Lepomiswere unaffected by Dreissena because of abundant benthicfood. The final total mass of Dreissena was significantlygreater in short- than long-residence mesocosms. Impacts of Dreissena on planktonic food webs may not only depend on thedensity of zebra mussels but also on the residence time of thesurrounding water and the resupply of seston.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003048431234
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic variability in the European minnow, Phoxinus phoxinus (L.) (1997)
    Springer
    Hydrobiologia 364 (1997), S. 183-188 
    Details
    ISSN: 1573-5117
    Keywords: fish ; genetic variability ; protein polymorphism ; heterosis ; heterozygosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An electrophoretic study of genetic variation at 11 loci was performedfor a population of European minnows, Phoxinus phoxinus (L.). Ten loci, EST-1 *, EST-2 * EST-3 *,GPD-1 *,GPD-2 *,GPI-1 *,GPI-2 *,MPI *,6PGD * and PGM * were polymorphic. IDH *wasmonomorphic. The mean number of heterozygotic loci over all 176 fish was 3.05 ± 0.104(SE). Observed mean heterozygosity was 0.28±0.058(SE) and expected mean heterozygosity was 0.27±0.054(SE). EST-2 *, EST-3 * andPGM * were not in Hardy-Weinberg equilibrium. Length,condition, parasite numbers or male breeding characters, i.e. red colorationand tubercles, were not influenced by single enzyme loci.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003151121442
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of fish on the breeding of the red-necked grebe Podiceps grisegena (Boddaert, 1783) (1997)
    Springer
    Hydrobiologia 344 (1997), S. 57-63 
    Details
    ISSN: 1573-5117
    Keywords: red-necked grebe ; breeding sites ; fish ; macroinvertebrates ; food competition ; physical and chemicalconditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I determined whether selection of breeding sites by thered-neckedgrebe Podiceps grisegena (Boddaert, 1783) was affectedbycompetition for food with fish. During 1987–89, ten ponds inScania, southern Sweden were investigated, five with(‘breedingsites’) and five without breeding red-necked grebe(‘non-breedingsites’). I quantified the biomass of fish and macrozoans(here:larger invertebrates and small vertebrates) and measured thephysical and chemical conditions of the ponds.Breeding sites had significantly lower relative fish abundancethannon-breeding sites. They were either devoid of fish or hadonly nine-spined sticklebackPungitius pungitius. The biomass (dry weight) ofmacrozoans,many of which represent a food resource for grebes, was 16timesgreater at breeding than at non-breeding sites. The physicalandchemical conditions of the ponds did not differsignificantly.These results are consistent with the hypothesis thatcompetitionfor macrozoans occurs between red-necked grebe and fish andthat adense population of many fish species caused red-necked grebestoavoid otherwise acceptable breeding sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002946109511
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  • 10
    Electronic Resource
    Electronic Resource
    Tolerance levels of redbreast tilapia, Tilapia rendalli (Boulenger, 1896) to natural suspended silt (1997)
    Springer
    Hydrobiologia 344 (1997), S. 11-18 
    Details
    ISSN: 1573-5117
    Keywords: fish ; silt ; exposure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tilapia rendalli was exposed to various siltconcentrationsfor different exposure periods to determine LC50 andsublethalconcentration ranges. The extent of damaging effects, if any,ofsuspended silt on the exposed fish, were investigated by meansofscanning electron microscopy. The LC50 values rangedbetween21 to 24 g l™1 and 42–48 g l™1 for juveniles andadultsrespectively. The silt concentrations tolerated by the testfisheswere above those found in most natural waters. The resultstherefore support the hypothesis that suspended silt is lethaltofish at concentrations higher than those naturally observed insurface water. The observed mortalities can be attributed tothecombined physical effects of high silt concentrations andassociated reduction in dissolved oxygen levels. To preventfishmortalities and other impacts on biota, anthropogenicactivitiesthat affect the natural variation in suspended siltconcentrationsin surface water should be carefully monitored and, wherepossible,be restricted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002985707694
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  • 11
    Electronic Resource
    Electronic Resource
    Polynuclear Aromatic Hydrocarbons (PAHs) in fish from the Red Sea Coast of Yemen (1997)
    Springer
    Hydrobiologia 352 (1997), S. 251-262 
    Details
    ISSN: 1573-5117
    Keywords: Red Sea ; PAHs ; oil pollution ; HPLC ; GC/MS ; fish ; origin ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A detailed analytical study using combined normal phase high pressure liquid chromatography (HPLC), gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) of Polynuclear Aromatic Hydrocarbons (PAHs) in fish from the Red Sea was undertaken. This investigation involves a preliminary assessment of the sixteen parent compounds issued by the U.S. Environmental Protection Agency(EPA). The study revealed measurable levels of Σ PAHs (the sum of three to five or six ring parent compounds) (49.2 ng g−1 dry weight) and total PAHs (all PAH detected) (422.1 ng g−1 dry weight) in edible muscle of fishes collected from the Red Sea. These concentrations are within the range of values reported for other comparable regions of the world. Mean concentrations for individual parent PAH in fish muscles were; naphthalene 19.5, biphenyl 4.6, acenaphthylene 1.0, acenaphthene 1.2, fluorene 5.5, phenanthrene 14.0, anthracene 0.8, fluoranthene 1.5, pyrene 1.8, benz(a)anthracene 0.4, chrysene 1.9, benzo(b)fluoranthene 0.5, benzo(k)fluoranthene 0.5, benzo(e)pyrene 0.9, benzo(a)pyrene 0.5, perylene 0.2, and indeno(1,2,3-cd)pyrene 0.1 ng g−1 dry weight respectively. The Red Sea fish extracts exhibit the low molecular weight aromatics as well as the discernible alkyl-substituted species of naphthalene, fluorene, phenanthrene and dibenzothiophene. Thus, it was suggested that the most probable source of PAHs is oil contamination originating from spillages and/or heavy ship traffic. It was concluded that the presence of PAHs in the fish muscles is not responsible for the reported fish kill phenomenon. However, the high concentrations of carcinogenic chrysene encountered in these fishes should be considered seriously as it is hazardous to human health. Based on fish consumption by Yemeni‘s population it was calculated that the daily intake of total carcinogens were 0.15 µg/person/day.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003048011029
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  • 12
    Electronic Resource
    Electronic Resource
    Top-down control in freshwater lakes: the role of nutrient state, submerged macrophytes and water depth (1997)
    Springer
    Hydrobiologia 342-343 (1997), S. 151-164 
    Details
    ISSN: 1573-5117
    Keywords: top-down control ; shallow lakes ; trophic structure ; trophic cascade ; macrophytes ; zooplankton ; fish ; biomanipulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on data from 233 Danish lakes, enclosure experiments, full-scaleexperiments and published empirical models we present evidence that top-downcontrol is more important in shallow lakes than in deep lakes, excepting lakeswith a high abundance of submerged macrophytes. The evidence in support is: (1)That at a given epilimnion total phosphorus concentration (TP) the biomass offish per m2 is independent of depth, which means that biomassper m3is markedly higher in shallow lakes. (2) That the biomass of benthic invertebratesis higher in shallow lakes, which means that the benthi-planktivorous fish areless dependent on zooplankton prey than in deep lakes. By their ability to shiftto zooplankton predation their density can remain high even in periods whenzooplankton is scarce and they can thereby maintain a potentially high predationpressure on zooplankton. (3) That the possibilities of cladocerans to escapepredation by vertical migration are less. (4) That the zooplankton:phytoplanktonmass ratio per m2 is lower and presumably then also thegrazing pressure onphytoplankton. (5) That nutrient constraints appear to be weaker, as evidenced bythe fact that at a given annual mean TP, summer TP is considerably higher inshallow lakes, especially in eutrophic lakes lacking submerged macrophytes. (6)That negative feedback on cladocerans by cyanobacteria is lower as cyanobacterialdominance is less frequent in shallow lakes and more easily broken (at least inNorthern temperate lakes), and (7) That top-down control by benthi-planktivorousfish is markedly reduced in lakes rich in submerged macrophytes because theplants serve as a refuge for pelagic cladocerans and encouragepredatory fish at the expense of prey fish. We conclude that manipulation of fishand submerged macrophytes may have substantial impact on lake ecosystems, inparticular in shallow eutrophic lakes. On the contrary, if the conditions formore permanent changes in plant abundance or fish community structure are lackingthe feed-back mechanisms that endeavour a return to the original turbid state willbe particularly strong in shallow lakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017046130329
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  • 13
    Electronic Resource
    Electronic Resource
    Lake Volkerak-Zoom: a lake shifting from the clear to the turbid state (1997)
    Springer
    Hydrobiologia 342-343 (1997), S. 367-376 
    Details
    ISSN: 1573-5117
    Keywords: phytoplankton ; zooplankton ; eutrophication ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lake Volkerak-Zoom (area 6000 ha, mean depth 5 m) was createdin1987 by isolating a part of the Eastern Scheldt estuary. A fewyears after enclosure the new freshwater lake was cleardespite ahigh phosphorus loading. However from 1990 on the transparencydropped.This paper describes the transition from the clear to theturbidstate of lake Volkerak-Zoom. The processes responsible for theultimate lowering of the transparency in the period 1988–1994willbe discussed and also the measures necessary to meet thetargetsituation: clear water with a transparency of 2 m. From 1990ontransparency is decreasing due to an increasing algal biomass,probably caused by a reduced grazing of the zooplankton. It ispossible that deterioration of the food quality (by increasedcyanobacterial blooms) reduced the zooplankton grazing.However,there are indications that increased mortality, caused by fishpredation, played the most important role in the reduction ofthezooplankton grazing. In 1992 the recruitment of fish,especially ofroach (Rutilus rutilus), was high (c. 40 kg ha−1).Thiscaused a high predation pressure on the zooplankton and isshown bya decrease of the mean length and vertical migration of Daphnia in 1992. In the same year the largest zooplanktonspecies,Daphnia pulex, disappeared from the lake. Smallerzooplanktonspecies with a lower grazing capacity remained. Because of thedecreased grazing, the algal biomass increased and thetransparencydropped. We expect that inthe future the lake will become more turbid. As an additionalmeasure to P-reduction, removing of fish is suggested to meetthetarget situation: a lasting clear water state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017043524394
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  • 14
    Electronic Resource
    Electronic Resource
    The status and distribution of lake sturgeon, Acipenser fulvescens, in the Canadian provinces of Manitoba, Ontario and Quebec: a genetic perspective (1997)
    Springer
    Environmental biology of fishes 48 (1997), S. 299-309 
    Details
    ISSN: 1573-5133
    Keywords: postglacial recolonization ; anthropogenic influences ; fish ; Acipenseridae ; conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetic analysis of mitochondrial DNA sequence variation indicates that most of a sample of 396 lake sturgeon, Acipenser fulvescens, from the northern part of their range belonged to either one of two haplotypes. The vast majority of fish from the Great Lakes/St. Lawrence and Mississippi drainages were of a single haplotype while those from the Hudson/James Bay were composed of both haplotypes. This haplotypic distribution suggests that fish from one refugium (possibly Missourian) recolonized the Hudson-James Bay drainage while those from a second (possibly Mississippian) recolonized the Laurentian Great Lakes and St. Lawrence River. Lake sturgeon still inhabit much of their native postglacial distribution in Manitoba, Ontario and Quebec. However, the stresses of commercial overexploitation and habitat alteration, usually through hydroelectric dam construction and operation, have either singly or in tandem brought about the reduction, if not extirpation, of some populations within the range. The largest zone of extirpation and population reduction has occurred in the Lake Winnipeg drainage area, which covers more than one-third of Manitoba. Other areas where populations have been reduced to remnant levels, if not extirpated, include the lower Laurentian Great Lakes of Lake Ontario and Lake Erie. In northern Ontario, lake sturgeon populations whose riverine habitats have been fragmented by two or more dams are substantially reduced from their former levels. In Quebec, more attention has been paid to limiting the exploitive stresses on lake sturgeon populations. Combination of the genetic and status data suggests that both northern and southern populations of lake sturgeon (possibly from two glacial refugia) have been impacted severely from anthropogenic influences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007367818353
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  • 15
    Electronic Resource
    Electronic Resource
    Weight-length relationship and condition of the characiform Triportheus guentheri (1997)
    Springer
    Environmental biology of fishes 50 (1997), S. 319-330 
    Details
    ISSN: 1573-5133
    Keywords: condition factor ; biometric indices ; Brazil ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sources of variations in the weight-length relationship parameters, and in the Fulton's, allometric, and relative condition factors (K) of the characiform fish Triportheus guentheri were investigated. The use of these indices as indicators of condition were also discussed. The 2899 females and 2491 males were captured with gill nets from January 1986 to March 1988 in Três Marias Reservoir (18° 15′ and 45° 15′ W), Brazil. Weight-length relationship parameters varied monthly in both sexes mainly due to the skewness of the relative frequency of the number of fish per body length. This suggests that a selective sample and/or the population length structure may strongly influence the estimate of those parameters. The K showed high correlations (r ≥ 0.99) among themselves. Their variations were ascribed to carcass weight in both sexes when analyzed by month, or to the ovary weights when analyzed by female gonad development intervals. The monthly weight-length relationship parameters of T. guentheri presented low or null correlation with K, except for the female's coefficient of regression. Problems using these parameters as indicators of condition suggested that they are not good indices to express condition. Some restrictions regarding the use of K are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007316028288
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  • 16
    Electronic Resource
    Electronic Resource
    General response patterns of fish populations to stress: an evaluation using an individual-based simulation model (1997)
    Springer
    Journal of aquatic ecosystem stress and recovery 6 (1997), S. 15-31 
    Details
    ISSN: 1573-5141
    Keywords: contaminants ; fish ; general response patterns ; individual-based ; population dynamics ; simulation model ; yellow perch ; walleye
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract General response patterns of fish populations tostress, originally proposed by Colby for fisheriesrehabilitation and later adapted by Munkittrick forcontaminants, were evaluated using an individual-basedsimulation model. General response patterns relatechanges in population-level variables to the type ofstress. The model follows the daily growth,mortality, and spawning of individual yellow perch andwalleye through their lifetime, and was corroboratedusing Oneida Lake data. Two versions of the model wereused: population (yellow perch only) and community(dynamic predation on yellow perch by walleye). Eightstresses were imposed on the population and communityversions of the model and 100-year simulations wereperformed. Response patterns were defined by changesin predicted yellow perch mean population abundance,mean age of adults, and mean adult growth (representedby mean length at age-7). Proposed response patternswere similar to those predicted using the populationversion of the model. Simulations using the communityversion of the model distorted the response patterns,either causing amplification, dampening, or reversalof many of the patterns. Predicted response patternsbecame unique when additional variables were included.Our model results suggest that caution is appropriatein interpreting general response patterns based onmean age, or when the population of interest plays amajor role in a relatively simple food web. The responsepattern approach may be better at identifying the lifestage impacted rather than the mechanism of the stress.
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    URL: http://dx.doi.org/10.1023/A:1008280503843
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    Characterization of molecular variants of GnRH, induction of spermiation and sex reversal using salmon GnRH-A and domperidone in the protogynous diandric fish, Synbranchus marmoratus Bloch, (Teleostei, Synbranchidae) (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 425-436 
    Details
    ISSN: 1573-5168
    Keywords: fish ; GnRH ; domperidone ; hermaphroditism ; protogynous ; diandric ; sex reversal ; spermiation ; Synbranchidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper studies the molecular variants of gonadotropin-releasing hormone (GnRH) present in the brain of the protogynous swamp eel, Synbranchus marmoratus, and the effects of the administration of salmon GnRH analogue (sGnRH-A) and the dopamine receptor antagonist, domperidone (DOM) on final maturation and gamete release in this species. Evidence for the presence of two GnRH variants, sGnRH and cIIGnRH were obtained by reverse phase high-pressure liquid chromatography (RP-HPLC) and radioimmunoassay with different antisera. The effects of treatment with sGnRH-A+DOM were checked by three ways: oocyte and milt release by stripping, histological analysis of the gonadal tissue, and androgen serum levels at different times throughout the experiment. In males, spermiation was induced after three weeks of treatment. In the female group, sGnRH-A+DOM did not induce ovulation at the end of the experiment. Histological analysis of the gonads from the female group showed evidence of sex reversal. All the treated fish had elevated androgen serum levels from the third week, with respect to control fish. In all cases, serum estradiol levels were undetectable. These results suggest that treatment with sGnRH analog and DOM induce sex reversal in female and spermiation in males.
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    URL: http://dx.doi.org/10.1023/A:1007772416539
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    Plasticity of the properties of mitochondria from rainbow trout red muscle with seasonal acclimatization (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 531-541 
    Details
    ISSN: 1573-5168
    Keywords: mitochondria ; muscle ; thermal acclimatization ; fish ; substrate preferences ; phospholipid fatty acid composition ; oxidative capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cold-acclimation of rainbow trout brings only limited changes in muscle metabolic capacities, but marked modifications in membrane composition. Thus, we examined whether the functional properties of mitochondria from trout red muscle were modified by seasonal temperature acclimatization. Mitochondria from fall-acclimatized trout had higher maximal capacities (state 3 rates) for the oxidation of pyruvate and acyl carnitines at 12 and 20 °C than mitochondria isolated from summer-acclimatized trout. For these substrates, the increased oxidative capacity completely compensated for the seasonal drop in temperature. Pyruvate and palmitoyl carnitine were consistently the preferred substrates, while decanoyl and octanoyl carnitine were oxidized at higher rates than glutamine, particularly in fall trout. State 4 rates of oxygen uptake (obtained when all ADP has been converted to ATP) differed less among substrates, but varied seasonally. State 4 rates at 12 and 20 °C were higher in mitochondria isolated from fall than summer trout. At low temperatures, the Q10 of both maximal and state 4 rates of substrate oxidation tended to be higher for mitochondria from fall trout. The apparent Arrhenius activation energy (Ea) for mitochondrial pyruvate oxidation was higher in fall than summer trout whereas the Ea’s for palmitoyl carnitine and decanoyl carnitine oxidation did not change. The fatty acids of mitochondrial phospholipids from fall trout were more polyunsaturated than those from summer trout, with 12% more double bonds occurring than in summer trout, suggesting that membrane restructuring may be involved in the observed compensatory responses.
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    URL: http://dx.doi.org/10.1023/A:1007708826437
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    Reproduction related immunoglobulin changes in rainbow trout (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 415-421 
    Details
    ISSN: 1573-5168
    Keywords: fish ; trout ; reproduction ; seasonal changes ; immunoglobulin ; testosterone ; estradiol-17β ; 11-ketotestosterone ; water temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Annual changes in plasma immunoglobulin (IgM) levels were investigated in three strains of rainbow trout Oncorhynchus mykiss which have different spawning periods, i.e., September–October, November–December, and January, reared under constant water temperature and natural day length. Plasma IgM levels decreased during the spawning season in all strains tested. The IgM changes became reversed in response to significant increases in plasma testosterone (T) and estradiol-17β in females and T and 11-ketotestosterone in males. Though the IgM decline showed a connection with suppressed immunocompetence, since many mature fish caught fungal diseases, no clear differences were observed in the plasma IgM levels between infected and noninfected fish during the spawning season. Incidentally, plasma IgM levels in infection prone fish were higher than in noninfection prone fish prior to the spawning season, whereas coincident differences in the plasma steroid levels were observed. Immature fish reared under lower water temperatures showed lower IgM levels. The effect of water temperature may have to be considered when analyzing the defense mechanism during the spawning season in rainbow trout.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007795827112
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    Transcriptional regulation of fish growth hormone gene (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 237-246 
    Details
    ISSN: 1573-5168
    Keywords: fish ; growth hormone gene ; thyroid hormone ; transcription ; DNA response element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcription of growth hormone (GH) genes in vertebrates depends, among other factors, on pituitary specific transcription factors (such as Pit-1) and on thyroid hormone (TH) and TH receptors. Gel retardation experiments indicated the presence of proteins in the carp pituitary nuclear extract that specifically bind the Pit-1 DNA response element and the adjacent putative TH DNA response element (TRE), on the Atlantic salmon (Salmo salar) GH proximal promoter. The putative TRE element competes effectively in vitro in gel retardation assays with 4×TREpal, a consensus TRE element, on zebrafish (Danio rerio) purified recombinant TH receptor (zfTHR). The zfTHR/TRE complex can also be further identified with antibodies to rat THR that causes the complex a supershift in gel retardation assay. Cross competition was observed in nuclear extracts between the TRE and Pit-1 sites. It was found that 100 molar fold excess of Pit-1 binding element can compete effectively with the TH binding element and reduce its binding activity. The endogenous TRE binding element, on the other hand, cannot effectively reduce the binding activity of the Pit-1 DNA binding element. This unexpected competition between the two sites was examined in the presence and absence of the hormones: TH, 9-cis retinal, and TH + 9-cis retinal. The addition of the two hormones together significantly increased the binding properties of the TH response element as compared to its binding in the absence of the hormones, and also improved its binding activity in the presence of the Pit-1 DNA competitor. In summary, the two adjacent sites that control GH gene transcription, Pit-1 and TRE, on the fish GH promoter exhibit some degree of interaction between their respective transcription factors, the Pit-1 protein and the thyroid/retinoic acid receptors.
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    URL: http://dx.doi.org/10.1023/A:1007762325604
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    Critical thermal maxima of diploid and triploid brook charr, Salvelinus fontinalis (1997)
    Springer
    Environmental biology of fishes 49 (1997), S. 259-264 
    Details
    ISSN: 1573-5133
    Keywords: triploidy ; thermal tolerance ; lethal limits ; brook trout ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The purpose of this experiment was to determine whether diploid and triploid brook charr, Salvelinus fontinalis, differ in their critical thermal maxima (CTM). Two age classes were tested (underyearlings, having average weight of 25 g, and yearlings, having average weight of 668 g) at two rates of temperature increase (2° C h-1 and 15° C h-1). No effect of ploidy on CTM was found. Fish exposed to the faster rate of temperature increase had higher CTM values than those exposed to the slower rate (underyearlings: 29.5 ± 0.1° C versus 29.1 ± 0.1° C in one trial and 29.8 ± 0.1° C versus 28.3 ± 0.1° C in a second trial; yearlings: 29.3 ± 0.1° C versus 27.7 ± 0.1° C in two trials, p 〈 0.001 in all cases). Underyearlings had higher CTM values than yearlings (29.2 ± 0.1° C versus 28.5 ± 0.1° C, p 〈 0.05). Female yearlings, which were immature, had higher CTM values than males, which had previously matured as one-year-olds (28.8 ± 0.1° C versus 28.3 ± 0.1° C, p 〈 0.001).
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    URL: http://dx.doi.org/10.1023/A:1007361231325
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    Predation of zebra mussels by round gobies, Neogobius melanostomus (1997)
    Springer
    Environmental biology of fishes 50 (1997), S. 267-273 
    Details
    ISSN: 1573-5133
    Keywords: exotic species ; laboratory experiment ; size selectivity ; Great Lakes ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Preliminary gut analysis of a recent Great Lakes invader, the round goby, Neogobius melanostomus (7.0–8.4 cm), collected from the Detroit River, showed that they ate zebra mussels (58%), snails (6%), and other invertebrates (36%), including aquatic insects (Hexagenia), softshelled crayfish, and zooplankton. Because zebra mussels, Dreissena polymorpha, predominated as prey, we investigated the ability of round gobies to consume different size classes of zebra mussels. In laboratory experiments, we examined feeding preferences of three size classes of round gobies (5.5–6.9 cm; 7.0–8.4 cm; 8.5–10.3 cm standard length) on four different size classes of zebra mussels (6.0–9.9 mm, 10.0–12.9 mm, 13.0–15.9 mm, 16.0–18.9 mm). All sizes of round gobies ate zebra mussels 〈 10.0 mm. Only the largest size class of round gobies ate larger zebra mussels (10.0–12.9 mm) when all prey sizes were presented. The association between the total mass of zebra mussels available and the amount consumed by round gobies increased positively up to about 6.5 g of available mussels and then levelled off. Round gobies consumed an average of 1.0 g of mussels in 24 h. There was a significant positive relationship between gape size and standard length of round gobies. Although larger round gobies (over the size range of fish in our study) are able to consume larger zebra mussels, small mussels were preferred. Our findings suggest that the preference of small zebra mussels by round gobies has the potential to alter the size structure of zebra mussel populations.
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    URL: http://dx.doi.org/10.1023/A:1007379220052
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    Proton pumps in the fish gill and kidney (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 363-369 
    Details
    ISSN: 1573-5168
    Keywords: vacuolar ATPase ; proton pump ; gill ; kidney ; acid-base regulation ; ionic regulation ; chloride cell ; pavement cell ; cortisol ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The proton pump or vacuolar type H+-ATPase is an oligomeric protein responsible for electrogenic H+ secretion in a variety of acid-secreting epithelia. Recently, the proton pump was identified in both the gill and kidney of freshwater-adapted rainbow trout (Oncorhynchus mykiss). Using immunocytochemistry, H+-ATPase has been localized in the pavement cells and chloride cells of the lamellar epithelium. During periods of internal acidosis, there is a marked increase in the expression of the branchial proton pump as identified by Western analysis, immunocytochemistry and in situ hybridization. This augmented expression of proton pumps occurs concomitantly with a marked increase in branchial acid excretion and Na+ uptake. Immunocytochemical studies suggest that the pavement cell, rather than the chloride cell, is the predominant site of acid excretion during periods of acidosis. These findings are consistent with the notion that in freshwater teleosts, Na+ uptake and H+ excretion are linked via the coupling of the electrogenic proton pump to apical membrane Na+ channels. This mechanism may be controlled by hormones including cortisol and/or growth hormone. The fish kidney plays an important role in regulating acidosis via the re-absorption of filtered HCO3 -. Recently, we have demonstrated using Western analysis and immunocytochemistry, the presence of proton pump in rainbow trout kidney and observed increased H+-ATPase expression during respiratory acidosis. These new findings suggest a role for the renal proton pump in acid-base regulation.
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    URL: http://dx.doi.org/10.1023/A:1007746217349
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    Seasonal variation of muscle metabolic organization in rainbow trout (Oncorhynchus mykiss) (1997)
    Springer
    Fish physiology and biochemistry 16 (1997), S. 139-155 
    Details
    ISSN: 1573-5168
    Keywords: season ; metabolic organization ; muscle ; fish ; temperature ; lipid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study examined how muscle metabolic organization varied during an annual cycle in which rainbow trout (Oncorhynchus mykiss) were held in outdoor holding ponds in which they were exposed to natural changes in temperature (range 0.2 to 15.6°C) and photoperiod. We examined the activities of glycolytic and mitochondrial enzymes in red and white muscle to evaluate whether trout enhance their capacity for lipid and carbohydrate oxidation during cold-acclimization. When assayed at habitat temperature, the enzyme activities generally increased in spring to reach a maximum in summer followed by a decrease in the fall. This led to significantly higher activities at warm than cold periods for all enzymes measured in red muscle and all but one in white muscle. The activities at 10°C provided little evidence for compensatory adjustments of aerobic capacity. Particularly in red muscle, enzyme levels at 10°C were generally lower during cold than warm periods. The variation of enzyme activities throughout the cycle was not due to changes in protein concentration, as the same responses were observed when activities were expressed per g wet mass or per mg protein. Although the aerobic capacity did not increase with cold-acclimatization, the relative capacity for lipid oxidation was higher in winter than in summer trout. In contrast, the relative capacity for aerobic glycolysis was higher in summer than in winter trout. Thus, the metabolic capacities of trout muscle undergo seasonal reorganization.
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    URL: http://dx.doi.org/10.1007/BF00004671
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    Vascular actions of neurohypophysial peptides in the flounder (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 313-318 
    Details
    ISSN: 1573-5168
    Keywords: teleost ; fish ; blood pressure ; arginine vasotocin ; isotocin ; ventral aorta ; dorsal aorta ; neurohypophysial hormone receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Free swimming, chronically cannulated flounder have been used to study the blood pressure effects of arginine vasotocin (AVT) and isotocin. The initial fall in dorsal aortic blood pressure following AVT injection coincided with an increase in ventral aortic blood pressure, suggesting AVT caused constriction of the arterio-arterial pathway. Ventral aortic blood pressure increased in a dose dependent manner with increasing AVT dose. Dorsal aortic blood pressure also increased following the initial fall but not in a dose dependent manner, the effect at higher doses being off set by branchial vasoconstriction. Isotocin also caused dorsal aortic blood pressure to fall due to branchial vasoconstriction, but no subsequent pressor effect was seen. Branchial vasoconstriction caused by both teleost neurohypophysial peptides suggests the presence of neurohypophysial peptide receptor(s) in the gill, although it is unclear as to whether this is a single common receptor or different populations for each peptide. The dorsal aortic pressor effect of AVT and its absence following isotocin injection suggests there may be other types of neurohypophysial receptors in post-branchial vascular beds. The vascular actions of AVT and isotocin suggest that these peptides may play some role in the regulation of blood pressure or regional blood flow distribution.
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    URL: http://dx.doi.org/10.1023/A:1007745821969
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    Regulation of gene expression and biological activity of rainbow trout estrogen receptor (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 123-133 
    Details
    ISSN: 1573-5168
    Keywords: reproduction ; steroid receptors ; estradiol ; estrogen receptor ; vitellogenin ; liver ; hepatocyte ; gene transcription ; mRNA stability ; fish ; rainbow trout
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rainbow trout estrogen receptor (rtER) concentration was highly induced in the liver after in vivo estradiol (E2) treatment or in vitro, in hepatocyte aggregate culture. Determination of transcription rate and mRNA half-life demonstrated that E2-induction of hepatic rtER level is caused essentially by an increase in the transcriptional and post-transcriptional activity of rtER gene. However, the expression of rtER gene in the liver seems to be down-regulated by glucocorticoids. We have used transient transfection assays with reporter plasmids linked to 5′ flanking regions of the rtER gene promoter, to identify cis-elements responsible for E2 inducibility. Deletion analysis localized a functional estrogen-responsive-element (ERE), near the transcription start site, with one mutation on the first base compared to the consensus sequence. This element and 200 bp fragment of the rtER promoter encompassing the ERE appear to be the major cis-acting element involved in the regulation of the gene. Data obtained from transfection experiments and footprinting analysis, suggested that the receptor is one of the major trans-factors implicated in the regulation of its own gene. However, interaction of ER with other transcription factors is required for maximal E2-stimulation.
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    URL: http://dx.doi.org/10.1023/A:1007706207857
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    Ontogeny of somatolactin mRNA in the gilthead sea bream Sparus aurata (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 247-252 
    Details
    ISSN: 1573-5168
    Keywords: somatolactin ; growth hormone ; mRNA ; Northern ; fish ; Sparus aurata ; embryos ; larvae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of somatolactin (SL) gene during embryonal and early stages of larval development of the teleost Sparus aurata was determined by Northern blot analysis. Poly(A+)RNA was prepared from a pool of embryos collected at early and late stages or from larvae collected on different days after hatching. When hybridized to Sparus aurata SL cDNA, SL specific mRNA was seen both in embryos and in larvae. Levels of SL increased from day 1 onwards and reached the highest levels on day 21. Re-hybridization with Sparus aurata growth hormone (GH) cDNA revealed GH specific mRNA first on day 6 post-hatching. Levels of GH increased to maximal levels on day 10 and then decreased on days 15 and 21, thereby confirming the pattern of GH expression (Funkenstein and Cohen 1996). The patterns of SL and GH gene expression are different in gilthead sea bream during embryonal and larval development. Furthermore, the presence of SL transcript in embryos, prior to pituitary gland development, suggests the possibility that SL mRNA of maternal origin may be present in the oocyte.
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    URL: http://dx.doi.org/10.1023/A:1007714409674
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    Gonadotropin-releasing hormone and gonadotropin in goldfish and masu salmon (1997)
    Springer
    Fish physiology and biochemistry 17 (1997), S. 1-8 
    Details
    ISSN: 1573-5168
    Keywords: gonadotropin-releasing hormone ; GnRH ; gonadotropin ; GTH ; reproduction ; reproductive endocrinology ; gonadal development ; fish ; goldfish ; masu salmon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Reproductive activities in vertebrates are regulated by an endocrine system, consisting of the brain-pituitary-gonad axis. In teleosts, gonadotropin-releasing hormone (GnRH) in the brain stimulates gonadotropin (GTH) release in the pituitary gland, but because of lack of the portal vessel, it is not known when and how much GnRH is released for the regulation of GTH release. There are multiple molecular types of GnRH in teleosts and several distinct populations of GnRH neurons in the brain. However, we do not know which types and populations of GnRH neurons regulate reproductive activities. Here we summarize our recent studies on GnRH and GTH in masu salmon Oncorhynchus masou and goldfish Carassius auratus. Immunocytochemistry showed the location and molecular types of GnRH neurons. Salmon (sGnRH) and chicken-II GnRH (cGnRH-II) neuronal fibers were widely distributed in the brain of both masu salmon and goldfish. Only sGnRH fibers were observed in the pituitary of masu salmon, whereas both sGnRH and cGnRH-II fibers were observed in the goldfish pituitary, indicating that species specific GnRH profiles are involved in the regulation of pituitary function in teleosts. A series of experiments in masu salmon and goldfish suggest that among GnRH neuron populations GnRH neurons in the ventral telencephalon and the hypothalamus regulate GTH release, and that GnRH of the terminal nerve origin is not essential to gonadal maturation and ovulation. The biological function of other GnRH neurons remains unkown. Two GTHs appear to be characteristic of teleost; however, regulation of reproduction by these GTHs is a question that remains to be elucidated. In salmonid species, it is proposed that GTH I stimulates early gonadal development, whereas GTH II acts in later stages. When GTH expression was examined in goldfish, both GTH I β and II β mRNA levels in the pituitary gland showed increases in accordance with gonadal development, unlike the sequential expression of GTH subunits in salmonids. The expression of these GTH subunit mRNAs were affected by water temperature, starvation, and steroid hormones in goldfish, but in what manner these two GTHs regulate gonadal development remains to be clarified.
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    URL: http://dx.doi.org/10.1023/A:1007764430746
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    Effects of biomanipulation in the large and shallow Lake Wolderwijd, The Netherlands (1997)
    Springer
    Hydrobiologia 342-343 (1997), S. 335-349 
    Details
    ISSN: 1573-5117
    Keywords: eutrophication ; lake restoration ; biomanipulation ; fish ; zooplankton ; phytoplankton ; macrophytes ; transparency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Since the early seventies, Lake Wolderwijd (2650 ha, mean depth1.5 m) suffered from cyanobacterial blooms, turbid water and a poorsubmerged vegetation as a result of eutrophication. From 1981onwards the lake was flushed with water low in phosphorus and highin calcium bicarbonate. Total-P and chlorophyll a in the lakemore than halved, but Secchi depth in summer increased from 0.20 to0.30 m only. In the hope of triggering a shift from thealgae-dominated turbid water state to a macrophyte-dominated clearwater state, the lake was biomanipulated during winter 1990/1991.The fish stock, mainly bream (Abramis brama) and roach (Rutilus rutilus),was reduced from 205 to 45 kg ha−1. In May1991, 575 000 (217 ind ha−1) pike fingerlings (Esoxlucius) were introduced. In spring 1991 the lake cleared as aresult of grazing by Daphnia galeata. The clear water phaselasted for only six weeks. Macrophytes did not respond as expectedand most of the young pike died. However, from 1991 to 1993 thesubmerged vegetation is gradually changing. Characeae began tospread over the lake (from 28 ha in 1991 to 438 ha in 1993). Thewater over the Chara meadows was clear, probably as a resultof increased net sedimentation in these areas. It is hypothesizedthat expansion of the Chara meadows might ultimately resultin a shift of the whole lake to a lasting clear water state. Inorder to promote the Chara, the fish stock reductions aimedat a spring clear water phase should be continued.
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    URL: http://dx.doi.org/10.1023/A:1017088701621
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    Drift ecology of western catostomid larvae with emphasis on Warner suckers, Catostomus warnerensis (Teleostei) (1997)
    Springer
    Environmental biology of fishes 49 (1997), S. 187-195 
    Details
    ISSN: 1573-5133
    Keywords: Pleistocene lakes ; drift behavior ; Catostomidae ; fish ; larvae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We studied drift ecology of Warner sucker, Catostomus warnerensis, larvae in streams of Warner Valley, Oregon in 1992 and 1993 in part to determine whether downstream transport of larvae limits juvenile recruitment. Variation in runoff for the two years was extreme, where peak discharge in 1992 was two orders of magnitude lower than peak discharge in 1993. We deployed drift nets in low-gradient stream sections that are modified by diversions. Low catches of drifting sucker larvae (zero in 1992 and two in 1993) indicate that losses into diversions were probably minimal. In 1992, we conducted in situ experiments to determine how sucker larvae behaved when exposed to high velocity current by placing individuals of various sizes in mid-channel and tracking drift responses by snorkeling. Even the smallest larvae used did not drift far (2.6 m) or for very long (0.97 min), as they resisted downstream transport by exploiting cover provided by aquatic plants and debris. We also recorded locations of larvae during a 24-hour cycle to determine whether positions occupied during the day changed at night. We found that groups were positioned closer to shore at night in 1993 than in 1992, suggesting that larvae reduced the likelihood of becoming entrained into swift current by moving away from mid-channel at night when visual orientation is impaired. These patterns of drift avoidance are different from behaviors of other western catostomid larvae, potentially because terminal lake habitat in Pleistocene basins such as the Warner Valley has been unreliable.
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    URL: http://dx.doi.org/10.1023/A:1007329010680
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    How light, a predator, and experience influence bluegill use of shade and schooling (1997)
    Springer
    Environmental biology of fishes 49 (1997), S. 79-87 
    Details
    ISSN: 1573-5133
    Keywords: behavior ; predator‐prey interaction ; shade ; schooling ; largemouth bass ; fish ; Lepomis macrochirus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bluegills, Lepomis macrochirus, form schools and use shade to avoid predators. How light intensity, predators, and experience might affect antipredator behavior of bluegill are not well understood. Hence, we evaluated use of shade and schooling by naive (hatchery) and experienced (wild) bluegills (50–60 mm total length) at four light levels (1.5, 85, 169, 340 lux) in the presence and absence of a model predator in experimental pools. Naive bluegills used shade extensively at all light levels, even when the predator was in the shade. They rarely schooled, preferring to shoal in the shade. Experienced bluegill used shade when the predator was in the open and avoided shade when the predator was there. Schooling was more prevalent at low light levels when shade was less intense. Use of shade became an increasingly important behavior at higher light levels, unless the predator was in the shade. A shaded predator caused experienced bluegills to shoal tightly in the opposite, open area. These data suggest naive bluegills may not have considered the model predator a threat. Their behavior suggests avian predator avoidance, a possibility given that avian predators were present at the hatchery. Experienced bluegill employed behaviors that would be useful in avoiding piscine predators.
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    URL: http://dx.doi.org/10.1023/A:1007353314602
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    Effects of salinity on survival, growth, metabolism, and behavior in juvenile hogchokers, Trinectes maculatus fasciatus (Achiridae) (1997)
    Springer
    Environmental biology of fishes 49 (1997), S. 323-331 
    Details
    ISSN: 1573-5133
    Keywords: osmoregulation ; migration ; life history pattern ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To understand the biological significance of the southern hogchoker's seasonal migration pattern, the effects of salinity (0, 7 and 15 ppt) on survival, growth, metabolism, and behavior were examined. Survival averaged 96% and salinity did not affect (p = 0.25) the growth rates of juvenile hogchokers during the 60 day experimental growth period. However, oxygen consumption rates suggest that juvenile metabolism is influenced by salinity. Circadian patterns of metabolic rates were present in the 7 and 15 ppt treatments, but absent in the freshwater group. The juveniles in the 7 ppt treatment exhibited significantly (p 〈 0.05) lower overall rates than the freshwater fish, while the fish in the 15 ppt condition had intermediate metabolic rates. Juvenile hogchokers also showed shifts in diel activity and feeding patterns among salinities, with the active time period shortening with increasing salinity. The main conclusion is that juvenile salinity intolerance is not the driving mechanism of their migration pattern, but salinity does affect juvenile metabolism and behavior. The metabolic effects of salinity can explain summer migration in juvenile hogchokers. Additionally, the shifts in their behavioral responses can generally be explained by the summer migration movements.
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    URL: http://dx.doi.org/10.1023/A:1007361417759
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    A modified decalcification technique for enhancing growth bands in deep-coned vertebrae of elasmobranchs (1997)
    Springer
    Environmental biology of fishes 50 (1997), S. 225-230 
    Details
    ISSN: 1573-5133
    Keywords: Galeus melastomus ; blackmouth catshark ; nitric acid ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A technique for enhancing growth bands on vertebrae was assayed using 477 centra from blackmouth catsharks, Galeus melastomus. Specimens were caught at depths between 200 and 800 meters off the southern Portuguese coast (Algarve) during an IPIMAR research cruise in August 1994. Total lengths ranged from 12 to 71 cm. Standard vertebral ageing techniques, such as silver nitrate impregnation, haematoxylin staining, grinding and shading failed to produce clearly contrasting bands. A method solely based on vertebra decalcification with nitric acid (5%) yielded the most satisfactory results. This technique provided clear band differentiation and was used by two independent readers. The analysis of differences in band counts between readers was based on: percent of disagreements, percent of disagreement by length group, index of average percent error and Wilcoxon's signed ranks test. The majority of differences corresponded to only one band of disagreement and disagreements have been found to increase with length, which stresses the need for a larger sampling effort on the larger and older individuals. The index of average percent error was estimated as 4.6% and no statistical differences were detected between readers' results.
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    URL: http://dx.doi.org/10.1023/A:1007368025164
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    Feeding ecology and interannual variations in diet of southern bluefin tuna, Thunnus maccoyii, in relation to coastal and oceanic waters off eastern Tasmania, Australia (1997)
    Springer
    Environmental biology of fishes 50 (1997), S. 275-291 
    Details
    ISSN: 1573-5133
    Keywords: fronts ; shelf ; oceanography ; scombrid ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The diets of 1219 southern bluefin tuna, Thunnus maccoyii, from inshore (shelf) and offshore (oceanic) waters off eastern Tasmania were examined between 1992 and 1994. Immature fish (〈 155 cm fork length) made up 88% of those examined. In all, 92 prey taxa were identified. Inshore, the main prey were fish (Trachurus declivis and Emmelichthys nitidus) and juvenile squid (Nototodarus gouldi). Offshore, the diversity was greater, reflecting the diversity of micronekton in these waters. Interestingly, macrozooplankton prey (e.g. Phronima sedentaria) were prevalent in tuna 〉 150 cm. The offshore tuna, when in subantarctic waters, ate relatively more squid than when in the East Australia Current. In the latter, fish and crustacea were more important, although there were variations between years. No relationship was found between either prey type or size with size of tuna. Feeding was significantly higher in the morning than at other times of the day. The mean weight of prey was significantly higher in inshore-caught tuna than in those caught offshore. We estimated that the mean daily ration of southern bluefin tuna off eastern Tasmania was 0.97% of wet body weight day−1. However, the daily ration of inshore-caught tuna was ∼ 3 times higher (2.7%) than for tuna caught offshore (0.8%) indicating that feeding conditions on the shelf were better than those offshore. Our results indicate that the inshore waters of eastern Tasmania are an important feeding area for, at least, immature southern bluefin tuna.
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    URL: http://dx.doi.org/10.1023/A:1007326120380
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    Effects of environmental hypoxia on oxygen consumption rate and swimming activity in juvenile white sturgeon, Acipenser transmontanus, in relation to temperature and life intervals (1997)
    Springer
    Environmental biology of fishes 50 (1997), S. 383-389 
    Details
    ISSN: 1573-5133
    Keywords: routine metabolic rate ; oxyconformer ; Acipenseridae ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Routine oxygen consumption rates (MO2) and swimming activity rates of juvenile white sturgeon were determined using closed respirometers at life-interval-appropriate temperatures: 10° C (0.2 g mean wet weight), 16° C (1.9 g mean wet weight), and 20° C (63.1 g mean wet weight) under normoxic (PO2 〉 140 mmHg) and moderately hypoxic (PO2=80 ± 5.0 mmHg) water conditions. At all temperatures and body sizes, hypoxia significantly depressed (p 〈 0.05) MO2 (57% mean reduction) and swimming activity (70% mean reduction). Overall mean MO2 was 228 µg O2 g-1 wet weight h-1 (normoxia) and 99 µg O2 g-1 wet weight h-1 (hypoxia). Thus, juvenile white sturgeon appear to decrease overall energy expenditures (hypometabolism) during hypoxia via reductions in spontaneous swimming activity. This is a life style that may increase survival during widespread or prolonged environmental hypoxia.
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    URL: http://dx.doi.org/10.1023/A:1007362018352
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    Size-dependent over-winter mortality of young-of-the-year roach, Rutilus rutilus (1997)
    Springer
    Environmental biology of fishes 50 (1997), S. 451-456 
    Details
    ISSN: 1573-5133
    Keywords: energy reserves ; fasting ; starving ; Lake Isojärvi ; Lake Päijänne ; fish ; cyprinid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Over-winter survival of starved and fed young-of-the-year roach from two lakes in central Finland was examined in the laboratory between November 1992 and May 1993. The mortality rate of starving YOY roach (total length 38 ± 2 mm) from small (ca. 0.5 km2), eutrophic Lake Isojärvi was 50%, whilst roach (total length 32 ± 3 mm) from large Lake Päijänne (1106 km2) suffered 42% mortality. Mortality was size-dependent among roach from Lake Isojärvi, smaller individuals being more vulnerable. There was not strict size limit for survival as proposed previously. However, it seems that within populations approximately the same proportion of smallest roach died independent of the absolute lengths of the fish. Mortality of fed roach from both lakes was always 〈 5%. This good survival indicates indirectly the importance of energy reserves in wintering. Lipid and protein content of fasting roach from lake Isojärvi decreased during the winter. In the group of fasting roach from Lake Päijänne the amount of lipids stored increased between November and March and decreased thereafter. No change in protein content of fasting fish from Lake Päijänne was observed.
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    URL: http://dx.doi.org/10.1023/A:1007302931943
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    Responses of fish exposed to a C9--11 linear alcohol ethoxylate nonionic surfactant in stream mesocosms (1997)
    Springer
    Ecotoxicology 6 (1997), S. 321-333 
    Details
    ISSN: 1573-3017
    Keywords: fish ; Pimephales promelas ; Lepomis macrochirus ; surfactant ; stream mesocosm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Bluegill sunfish (Lepomis macrochirus) and fathead minnow (Pimephales promelas) responses to a nonionic linear alcohol ethoxylate (LAE) surfactant were examined in 10-day laboratory and 30-day outdoor stream mesocosm experiments. Larval fathead minnow survival was determined in a 10-day laboratory study with nominal concentrations of 0, 1.0, 3.0, 7.0, 13.0 and 25.0 mg LAE l−1. Bluegill sunfish survival and growth and fathead minnow survival, reproduction and behaviour were evaluated in replicated stream mesocosms with mean measured concentrations of 0, 0.73, 2.04, 4.35, 5.7 and 11.24 mg LAE l−1. The 10-day laboratory No Observed Effect Concentration (NOEC) for larval fathead minnow survival was 1.0 mg l−1. The 30-day stream NOEC for bluegill sunfish survival and growth was 5.7 mg l−1. In the stream mesocosms, NOECs for adult fathead minnow survival, reproduction and behaviour were 2.04 mg l−1, 0.73 mg l−1 and 0.73 mg l−1, respectively. Surviving fathead minnows that had ceased reproduction following exposure to LAE in the streams re-established normal reproduction during a post- treatment observation period in the laboratory. Laboratory studies in conjunction with the stream mesocosm study yielded complementary results which provided a detailed assessment of threshold responses of fish to LAE
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    URL: http://dx.doi.org/10.1023/A:1018643214727
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    The difference in brown trout (Salmo Trutta L.) blood composition from acidic and limed sites of two rivers in Western Norway (1997)
    Springer
    Water, air & soil pollution 96 (1997), S. 203-210 
    Details
    ISSN: 1573-2932
    Keywords: acidification ; blood ; environment ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Certain blood morphology parameters: red blood cell (RBC) sizes; percentage of polymorphonuclear leukocytes and ratio polychromatocyte/RBC in Brown trout (Salmo trutta L.) from acidified water (mean pH value 4.94) and limed water (mean pH value 5.66) were investigated. The sizes of RBC long axises were significantly larger in fish from acidic environment than from limed condition (14.37 and 12.96μm respectively). The percentage of polymorphonuclear cells (7.86 and 3.32) and polychromatocyte/RBC ratio (0.079 and 0.019) were also significantly larger in fish from the acidified environment. Blood morphology parameters are concluded to be usefull for testing and detection of long-term acidic stress in fish in nature.
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    URL: http://dx.doi.org/10.1007/BF02407205
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    THE DIFFERENCE IN BROWN TROUT (SALMO TRUTTA L.) BLOOD COMPOSITION FROM ACIDIC AND LIMED SITES OF TWO RIVERS IN WESTERN NORWAY (1997)
    Springer
    Water, air & soil pollution 96 (1997), S. 203-210 
    Details
    ISSN: 1573-2932
    Keywords: acidification ; blood ; environment ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Certain blood morphology parameters: red blood cell (RBC) sizes; percentage of polymorphonuclear leukocytes and ratio polychromatocyte/RBC in Brown trout (Salmo trutta L.) from acidified water (mean pH value 4.94) and limed water (mean pH value 5.66) were investigated. The sizes of RBC long axises were significantly larger in fish from acidic environment than from limed condition (14.37 and 12.96 μm respectively). The percentage of polymorhonuclear cells (7.86 and 3.32) and polychromatocyte/RBC ratio (0.079 and 0.019) were also significantly larger in fish from the acidified environment. Blood morphology parameters are concluded to be usefull for testing and detection of long-term acidic stress in fish in nature.
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    URL: http://dx.doi.org/10.1023/A:1026404417464
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    Chemical contamination and associated liver diseases in two species of fish from San Francisco Bay and Bodega Bay (1997)
    Springer
    Ecotoxicology 6 (1997), S. 35-65 
    Details
    ISSN: 1573-3017
    Keywords: chemicalpollution ; fish ; sediment ; San Francisco Bay ; liver diseases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Starry flounder (Platichthys stellatus), white croaker (Genyonemus lineatus) and sediments were collected annually from selected sites within San Francisco Bay, and a reference site in Bodega Bay between 1984--1991. Fish livers were examined for toxicopathic lesions and analysed for selected chlorinated hydrocarbons (CHs) such as PCBs, DDTs, chlordanes and dieldrin; sediment and fish stomach contents were analysed for polycyclic aromatic hydrocarbons (PAHs) and CHs; and bile was analysed for PAH metabolites. Sediment concentrations of PAHs, PCBs and DDTs; bile concentrations of PAH metabolites; and liver concentrations of PCBs, dieldrin and chlordanes were generally significantly higher at all San Francisco Bay sites compared to the Bodega Bay reference site. For both species, hydropic vacuolation of biliary epithelial cells was the most prevalent liver lesion detected and was statistically associated with sediment and tissue concentrations of PAHs or their metabolites, PCBs, DDTs, chlordanes and dieldrin. Temporal trends analyses showed that at Hunters Point, sediment PAHs and CHs increased between 1984--1991, while liver concentrations of CHs decreased. Liver concentrations of dieldrin in starry flounder decreased at all three San Francisco Bay sites
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    URL: http://dx.doi.org/10.1023/A:1018654122479
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    Whole-catchment liming at Tjønnstrond, Norway: An 11-year record (1997)
    Springer
    Water, air & soil pollution 94 (1997), S. 163-180 
    Details
    ISSN: 1573-2932
    Keywords: acid deposition ; liming ; catchment ; lake ; water chemistry ; fish ; soil ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In June 1983 a whole-catchment liming experiment was conducted at Tjønnstrond, southernmost Norway, to test the utility of terrestrial liming as a technique to restore fish populations in remote lakes with short water-retention times. Tjønnstrond consists of 2 small ponds of 3.0 and 1.5 ha in area which drain a 25-ha catchment. The area is located at about 650–700 meters above sea-level in sparse and unproductive forests of spruce, pine and birch with abundant peatlands. A dose of 3 ton/ha of powdered limestone were spread by helicopter to the terrestrial area. No limestone was added to the ponds themselves. The ponds were subsequently stocked with brown and brook trout. Liming caused large and immediate changes in surface water chemistry; pH increased from 4.5 to 7.0, Ca increased from 40 to 200μeq/L, ANC increased from −30 to +70μeq/L, and reactive-Al decreased from about 10 to 3μmol/L. During the subsequent 11 years the chemical composition of runoff has decreased gradually back towards the acidic pre-treatment situation. The major trends in concentrations of runoff Ca, ANC, pH, Al and NO3 in runoff are all well simulated by the acidification model MAGIC. Neither the measured data nor the MAGIC simulations indicate significant changes in any other major ion as a result of liming. The soils at Tjønnstrond in 1992 contained significantly higher amounts of exchangeable Ca relative to those at the untreated reference catchment Storgama. In 1992 about 75% of the added Ca remains in the soil as exchangeable Ca, 15% has been lost in runoff, and 10% is unaccounted for. The whole-catchment liming experiment at Tjønnstrond clearly demonstrates that this liming technique produces a long-term stable and favourable water quality for fish. Brown trout in both ponds in 1994 have good condition factors, which indicate that the fish are not stressed by marginal water quality due to re-acidification. The water quality is still adequate after 11 years and 〉20 water renewals. Concentrations of H+ and inorganic Al have gradually increased and approach levels toxic to trout, but the toxicity of these are offset by the continued elevated Ca concentrations. Reduced sulphate deposition during the last 4 years (1990–94) has also helped to slow and even reverse the rate of reacidification. The experiment at Tjønnstrond demonstrates that for this type of upland, remote terrain typical of large areas of southern Norway, terrestrial liming offers a suitable mitigation technique for treating acidified surface waters with short retention times.
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    URL: http://dx.doi.org/10.1007/BF02407100
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    Variation in blood cell DNA in Carassius carassius from ponds near Chernobyl, Ukraine (1997)
    Springer
    Ecotoxicology 6 (1997), S. 187-203 
    Details
    ISSN: 1573-3017
    Keywords: genotoxicity ; Chernobyl ; fish ; flow cytometry ; DNA content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Blood from approximately 400 crucian carp, Carassius carassius, from 12 ponds in the Ukraine, was analysed by flow cytometry to assess the possible relationships between chronic contaminant exposure and variation in the cellular DNA content. The ponds were located 20--30 km from Chernobyl in areas that received 3.7 × 1010--3.7 × 1011 Bq 137Cs km-2 after the 1986 nuclear accident, as well as other radioactive and chemical contaminants. The fish populations consisted of both diploid and triploid individuals and the ploidy varied between ponds. Analysis of whole blood revealed aneuploid-like patterns in the DNA histograms of some fish, as well as hyperdiploid shoulders of the G0/G1 peak. The coefficient of variation (CV) of the G0/G1 peak has previously been employed to assess the variability in the DNA content of cells within individuals. The CV of individual fish varied between and within locations and very large CVs were found for some individuals. In some fish, DNA histograms showed a typical diploid or triploid cell population together with a smaller haploid population. Variations in the cellular DNA content similar to those reported here have been associated with exposure to radiation and other genotoxic agents in laboratory and field studies. However, the abnormalities we observed were not correlated with known contaminant distributions. While further work is needed, particuarly in areas with substantially higher levels of radioactivity, these results suggest that the Chernobyl accident may have long-term genetic consequences for wild organisms inhabiting contaminated areas
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    URL: http://dx.doi.org/10.1023/A:1018622710184
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    How many demersal fish species in the deep sea? A test of a method to extrapolate from local to global diversity (1997)
    Springer
    Biodiversity and conservation 6 (1997), S. 1523-1532 
    Details
    ISSN: 1572-9710
    Keywords: biodiversity ; deep sea ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Grassle and Maciolek (1992) estimated that there were of the order of 107 species of benthic macro-invertebrates in the world's deep sea soft sediments. Their estimate was extrapolated from the 798 species they sampled and the pattern of species diversity observed along a 176km transect on the continental slope of the northeast Atlantic Ocean. Relative to the deep sea invertebrate fauna, the deep sea fish fauna has been better sampled, at least in the upper 1500m. To test the validity of the Grassle and Maciolek method of extrapolation, we applied it to data from a survey of fishes along the continental slope off western Australia, a diverse and previously unsurveyed region. The resulting global estimate for the deep sea demersal fishes – 60000 species – was then compared with the number described to date, about 2650 species, and an estimate of total extant species. Our estimate, which considers the proportion of new species found in little-explored regions of the world ocean, such as off western Australia, and the number of new species expected in future taxonomic revisions, is a total of 3000–4000 species. The Grassle and Maciolek method appears invalid as a means to extrapolate global biodiversity from local surveys.
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    URL: http://dx.doi.org/10.1023/A:1018366419962
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    Iridoviruses associated with epizootic haematopoietic necrosis (EHN) in aquaculture (1997)
    Springer
    World journal of microbiology and biotechnology 13 (1997), S. 367-373 
    Details
    ISSN: 1573-0972
    Keywords: Amphibian ; aquaculture ; epizootic haematopoietic necrosis virus ; fish ; frog virus 3 ; Iridoviridae ; ranavirus ; reptile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Systemic infections of teleost fishes caused by iridoviruses have recently been recognized in Australia, Asia, Europe and the USA. These iridoviruses are different from those of the established genera Lymphocystivirus and Goldfish Virus 1-like Viruses of the family Iridoviridae. The agents exhibit similar physicochemical properties, are antigenically related and prove to be of high virulence to different teleost fishes in aquaculture. The first iridovirus, epizootic haematopoietic necrosis virus, responsible for an epizootic outbreak of haematopoietic necrosis in redfin perch, was reported in Australia. Some years later, similar iridovirus epizootics occurred in sheatfish and catfish in Europe. The Australian and the European isolates proved to be antigenically related and showed properties in common with frog virus 3, the type species of the genus Ranavirus of the Iridoviridae. Further iridovirus isolates from fish, amphibians and reptiles exhibited a close relationship with each other and with frog virus 3. It is important to note that the Australian amphibian iridovirus, Bohle iridovirus, was experimentally transmitted to teleost fish inducing high mortalities. The occurrence of similar viruses in different host species in the aquatic environment and their inter-species transmission emphasize the importance of health control in aquaculture.
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    URL: http://dx.doi.org/10.1023/A:1018563930712
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