Fish Movement Among Lakes: Are Lakes Isolated (original) (raw)
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Isolation vs. Extinction in the Assembly of Fishes in Small Northern Lakes
Ecology, 1998
To evaluate the roles of extinction and isolation in predicting richness and composition of fish assemblages in small forest lakes of Finland and Wisconsin, we analyzed data from 114 Finnish and 55 Wisconsin lakes 0.2-86.9 ha in area. Six isolation variables characterized properties of stream corridors, land barriers, and source pools of invading species; four extinction variables were related to habitat severity, lake area, and productivity. Two types of multivariate analyses were used: the nonparametric classification and regression trees (CART) and the parametric linear discriminant analysis (LDA). Both types of analyses showed that extinction variables were collectively more important than isolation variables in predicting richness and composition both in Finland and Wisconsin. We interpret that the greater importance of extinction vs. isolation results, not because isolation is unimportant, but because the probability of an arrival of a new species is much less than that of an extinction. Thus, the time after an extinction event before a subsequent invasion is long relative to the time after an invasion event before a subsequent extinction; consequently, fish assemblages sampled at a given point in time more likely represent the stamp of the extinctions than of the invasions. This conclusion was robust to the differences in the geomorphic settings and fish faunas of Finland and Wisconsin. However, the importance of individual isolation and extinction variables in determining richness and composition differed between the two regions, apparently more from differences in geomorphic settings than from differences in fish faunas. Influences of horizontal rather than vertical barriers over land and water were more apparent in Wisconsin, with its lower relief and higher incidence of lakes without stream connections; influences of the area of the nearest lake (representing the size of the available species pool) and stream gradient were more important in Finland, with its higher relief and higher incidence of lakes with stream connections. The importance of individual extinction variables also differed between the two regions, again reflecting differences in the geomorphic settings of the two lake districts and the strong influence that lake position in the landscape has in determining limnological features of the lake.
Biomanipulating streams: a supplementary tool in lake restoration
Removal of cyprinid fish is a widely used biomanipulation tool to transform turbid shallow eutrophic lakes in north temperate regions into a clear water state. We here evaluate the removal of cyprinids from streams as a supplement to lake fishing. Since cyprinids often aggregate in high densities in lake inlet/outlet streams during winter migration, removal of fish in this space-confined habitat may be cost-efficient as compared to fish removal in the lake habitat. In two consecutive years, we annually removed up to 35% of the dominant cyprinids from an inlet stream to a lake and argue that this could easily be increased with a more targeted fishing effort. Concurrently, we monitored species-and length-specific variation in migration propensity, to explore how this relates to efficient fish removal. Smaller planktivores generally had a much higher migratory propensity than larger benthivores. Hence, stream fishing specifically targets species and size groups that are less efficiently controlled with traditional lake fishing methods. As a rule of thumb, stream fishing is most efficient when water temperature is 2-6°C. Prior to implementing fish removals from streams, the potential evolutionary consequences of the targeted removal of migratory phenotypes should be considered.
Freshwater Biology, 2007
1. Classification of European lake fish assemblages can be based on fish-assemblage structure or morphological, geographical, physical and chemical lake attributes. However, substantial gaps in knowledge exist with respect to the correspondence between both classification approaches. 2. Here, we compiled fish assemblage data from 165 lakes situated in the European 'Central Plains' ecoregion. Cluster analysis of fish abundances was performed to compare fish assemblage types of the entire ecoregion with those from previous country-specific studies. Nonparametric group comparisons, classification trees and partial canonical ordinations were used to infer the correspondence between fish assemblage types and morphology, geographical position and nutrient concentration of the lakes. 3. Three distinct fish assemblages were revealed: vendace (Coregonus albula), ruffe (Gymnocephalus cernuus) and roach (Rutilus rutilus) lake types. Both latitude and lake depth were the best determinants of lake type, but total phosphorus (TP) concentrations were also important. Vendace lakes were deep and had low TP concentrations, whereas the shallower ruffe and roach lakes had higher TP values. Roach lakes were more frequent in the northwest area of the ecoregion, whereas ruffe lakes were more often found south of the Baltic Sea. 4. Controlling for the influence of nutrient concentration showed that lake morphology and geographical position were important determinants of fish assemblages. However, the variance explained was low (<20%), implying that biological interactions may also be important in forming the lake-specific fish assemblages. 5. The results suggest that fish assemblages differ between deep and shallow lakes, and between the northwest and southeast locations within the Central Plains ecoregion. Accordingly, establishment of depth-related lake morphotypes is needed, and the European ecoregions recommended to be used in evaluation systems according to the Water Framework Directive seem to be too coarse to reflect the subtle differences of fish species richness along geographical gradients.
The Homogenizing of Minnesota Lake Fish Assemblages
Fisheries, 1995
The loss of unique fish assemblages in Minnesota lakes was evaluated by comparing species presence in historical and most-recent surveys of both stocked and unstocked lakes. Fish stocking resulted in greater species richness but reduced fish assemblage diversity among stocked lakes. No significant changes occurred among unstocked lakes. Short-term goals of additional fishing opportunities were partially achieved through stocking by creating more opportunities to fish for walleye in more lakes. However, the resulting loss of fish assemblage diversity within a local management area was apparently not considered. Fisheries managers should consider the potential for loss of community diversity and preserve unique fish communities where they still exist.
Transactions of the American …, 1999
We assessed the effects of nonnative fish on native fish biodiversity, using assemblage data collected during 1991-1996 from 203 randomly selected lakes in the northeastern USA by the Environmental Monitoring and Assessment Program (EMAP) of the U.S. Environmental Protection Agency. An estimated 74% (Ϯ17.6%, 95% confidence interval) of the region's 10,608 lakes between 1 and 10,000 ha contain at least one introduced species. Based on our samples, nonnative individuals outnumbered natives in an estimated 31.5% (Ϯ11%) of lakes. Regression models indicated that native, introduced, and total species richness were associated with lake surface area, elevation, and lake depth (0.31 Յ R 2 Յ 0.81). The intensity of human disturbance in the watershed was positively associated with introduced species richness but not associated with native species richness. The number of nonnative species was a significant variable in the native-species regression models for the entire Northeast and for only one of five subregions, the Northeast Coastal Zone ecoregion. Of the types of fishes that have been introduced, littoral predators-primarily Micropterus-appeared to have the greatest negative effect on native species richness. Small or soft-finned species appeared to be the least tolerant of these introduced predators. Native brook trout and minnow assemblages, typical of northern lakes in the Northeast but now rare in the Adirondacks, appeared to be at the greatest risk from continued introductions in northeastern New England. Current among-lake () species diversity was associated more with regional diversity of lake types than with extent or dominance of nonnative species. Without quantitative historical data, it was not possible to demonstrate a homogenizing effect of introductions on lake fish assemblages.
The ecology of fish movement in six Lake Ontario tributaries
2011
Despite a rich literature on the ecology of freshwater fishes, the movement behaviour of many stream fish remains poorly understood, yet is expected to be important for key ecological and micro-evolutionary processes. The main purpose of my thesis was to improve our understanding of fish movements by evaluating the movement of multiple species across multiple streams and entire watersheds. I undertook three steps to achieve this: 1) a comparative study addressing whether information in natural history accounts provide reliable information for predicting the behaviour of other populations of stream fishes (Chapter 1); 2) adapted, tested and extended existing theory on sex-biased arrival by conducting a broad test of four hypotheses on stream fishes at spawning sites (Chapter 2); and 3) to extend and contribute to a management concern of broad interest regarding invasive species control by examining the degree to which fishes move between adjacent streams (Chapter 3). Comparisons betw...
Fish Assemblages: The Influence of Habitat and Hydrology
2009
Rivers and streams are irreplaceable resources for both human consumption and recreation. Disturbances of these ecosystems can lead to degradation of part, or aU, of the stream system. Alteration of habitat influences and changes the fauna within that environment. We sampled agricultural, headwat€f intermittent and perennid streams in the White Riv€f watershed in Delaware County in East-Central Indiana. We sampled 16 sites in May of 2007 using backpack electrofishing. Fish were identified and we assessed the response of fish assemblages and identified relationships in fish abundance and diversity with stream habitat and hydrology. We hypothesized tolerant fish species and lower species richness would characterize both agricultural and intermittent streams. We tested for a relafionship and interactlons among fish assemblages with habitat and hydrological variables. adivities can yield broad alterations in landscapes through tile drainage and channel 15 modifications (Allan 1995, Carpenter et at 1998. Quinn et al. 1997) that cause diffuse 16 nutrient and sediment pollution (Lammert and Allan 1999, Carpenter et al. 1998. Stewart 17 et al. 2001. Plantinga 1996). Cascading events may further alter stream habitat through 18 decreased stabilization of the existing channel. These habitat changes in response to 19 agricultural activities may alter fish communities. For example. Harding et al. (1998) 20 documented that fish in agricultural streams that occupy the streambed were replaced 21 by more tolerant species that use the water column. Marchetti and Moyle (2001) also 22 identified numerous effects of agricultural activity on streams caused by altered flow 23 regimes including changes in channel structure, sediment transport, species diversity.
A Landscape-Based Classification of Fish Assemblages in Sampled and Unsampled Lakes
Transactions of the American Fisheries Society, 2012
We related fish species patterns and landscape-scale environmental data from 216 Michigan lakes to identify repeatable types of fish assemblages, identify environmental factors related to assemblage types, and classify fish assemblages in unsampled lakes. Multivariate regression tree modeling of fish species abundances identified six assemblage types that were explained by degree-days during the ice-free period, lake surface area, and mean lake surface temperature. Warmwater species dominated southern lakes, while coolwater and coldwater species had higher abundances in northern lakes. Coolwater species were present in large southern lakes, whereas warmwater species were excluded from northern lakes that had low mean surface temperatures or low degree-days. These results suggest that patterns of lake fish assemblages are shaped by differences in climate as well as lake-specific differences in surface temperature regimes and in vertical availability of coldwater and coolwater habitats. Because we related fish patterns to readily available landscape-level data, our approach can be used to characterize fish assemblages in all lakes across broad geographic extents.
The effects of food-web management on fish assemblage dynamics in a north temperate lake
Journal of Fish Biology, 1999
ABSTRACT There was an intensive trawl fishery in the Enonselkä basin in Lake Vesijärvi (southern Finland) in 1989–1993 and thereafter the fishing intensity declined. The fish assemblage dynamics were studied both during the years of intensive trawling and for 3 years afterwards. Roach Rutilus rutilus dominated the fish assemblage before the mass removal. The intensive trawling effectively diminished the roach stock and the present fishing intensity has been sufficient to prevent its recovery. There were significant decreasing trends in the gillnet cpue (catch per unit effort) of bream Abramis brama (L.) and bleak Alburnus alburnus (L.) while increasing trend was observed in cpue of ruffe Gymnocephalus cernuus (L.) and vendace Coregonus albula (L.). Perch Perca fluviatilis L. and pikeperch Stizostedion lucioperca (L.) showed variations in cpue but no trends existed. The proportion of cyprinids decreased while that of percids and coregonids increased in the catches. The changes in the fish assemblage were induced by the intensive fishing and by the concomitant decline in the ecosystem productivity.