Advances in Understanding Landscape Influences on Freshwater Habitats and Biological Assemblages

2019 ◽  
Keyword(s):  
Regression Tree ◽  
Invasion Success ◽  
Data Sets ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Lake Ecosystems ◽  
Correlative Models ◽  
Aquatic Invasions ◽  
Freshwater Habitats ◽  
Spatial Grain

<i>Abstract.</i>—Lakes, like islands, have been model systems for testing important concepts in landscape ecology. Lake assemblage and community composition, generally, and the occurrence of invaders, specifically, are controlled by a range of factors across scales. Here, I use the example of Rainbow Smelt <i>Osmerus mordax </i>invasions in inland lakes to illustrate common problems in both predictive and explanatory models of invasive species distributions across landscapes. Using variables related to dispersal and regional- and lake-scale environment, I fitted a series of boosted regression tree models to examine the factors that explain Rainbow Smelt invasion success. These models illustrate the potential effects of extrapolation and nonequilibrium conditions, the role of human activities, and the difficulty of understanding the importance of biotic interactions in the spread of invasives. Understanding the factors controlling invasions should inform management and conservation of inland lake ecosystems. For this to be effective, a mechanistic framework is needed to untie correlations in potential driving factors. Emerging data sets with fine spatial grain and broad spatial extent will support the transition from correlative models to mechanistic understanding of aquatic invasions.

Advances in Understanding Landscape Influences on Freshwater Habitats and Biological Assemblages

2019 ◽  
Keyword(s):  
Random Forest ◽  
Air Temperature ◽  
Species Distribution ◽  
Aquatic Ecosystems ◽  
Species Distribution Models ◽  
Data Sets ◽  
Distribution Models ◽  
Correlative Models ◽  
Aquatic Invasions ◽  
Freshwater Habitats

<i>Abstract.</i>—Species distribution models are important tools for conservation and management of aquatic ecosystems. In this study, nine fish species (Caspian Lamprey <i>Caspiomyzon wagneri</i>, <i>Acanthalburnus urmianus</i>, <i>Alburnoides namaki</i>, <i>Capoeta buhsei</i>, Mangar <i>Luciobarbus esocinus </i>[also known as <i>Barbus esocinus</i>], <i>Luciobarbus xanthopterus</i>, <i>Mesopotamichthys sharpeyi</i>, <i>Glyptothorax silviae</i>, and <i>Iranocichla hormuzensis</i>) that are sensitive to habitat changes induced by human activities were predicted by species distribution models throughout rivers in Iran. The fish data used cover several time periods (1970–2000) obtained from databases originating from field sampling, several museums, and the literature. We considered seven environmental variables, including channel slope, bank-full width, wetted width, elevation, mean air temperature, range of air temperature, and annual precipitation to model distributions of all nine species using an ensemble forecasting approach. Models used included generalized linear models, generalized additive models, classification tree analysis, artificial neural networks, surface range envelopes, boosted regression trees, random forest, multivariate adaptive regression splines, and flexible discriminant analysis. Additionally, we compared known distributions of species with modeled distributions, and we used the models to identify potential habitats for the nine species outside previously sampled areas. True skill statistic for each species was, on average, greater than 0.80 (i.e., excellent). Moreover, whereas surface range envelopes for all species had the lowest performance, random forest and generalized boosting methods had the highest performance. Among species studied, Caspian Lamprey, <i>Luciobarbus xanthopterus</i>, and <i>Mesopotamichthys sharpeyi </i>were predicted only in basins where they had been previously detected. In contrast, other species (i.e., <i>Acanthalburnus urmianus</i>, <i>Alburnoides namaki</i>, <i>Capoeta buhsei</i>, Mangar, <i>Glyptothorax silviae</i>, and <i>Iranocichla hormuzensis</i>) were predicted not only in basins with previous records, but also in new basins. These results deepen our understanding of distribution patterns of the studied species in Iran and can be used to guide regional conservation planning, identify critical habitats for threatened species, and inform management and conservation of inland aquatic ecosystems. For this to be effective, a mechanistic framework is needed to untie correlations in potential driving factors. Emerging data sets with fine spatial grain and broad spatial extent will support the transition from correlative models to mechanistic understanding of aquatic invasions.

scholarly journals KTBoost: Combined Kernel and Tree Boosting

2021 ◽  
Author(s):  
Fabio Sigrist
Keyword(s):  
Hilbert Space ◽  
Reproducing Kernel ◽  
Predictive Accuracy ◽  
Reproducing Kernel Hilbert Space ◽  
Regression Tree ◽  
Regression Function ◽  
Data Sets ◽  
Regression Functions ◽  
Boosting Algorithm

AbstractWe introduce a novel boosting algorithm called ‘KTBoost’ which combines kernel boosting and tree boosting. In each boosting iteration, the algorithm adds either a regression tree or reproducing kernel Hilbert space (RKHS) regression function to the ensemble of base learners. Intuitively, the idea is that discontinuous trees and continuous RKHS regression functions complement each other, and that this combination allows for better learning of functions that have parts with varying degrees of regularity such as discontinuities and smooth parts. We empirically show that KTBoost significantly outperforms both tree and kernel boosting in terms of predictive accuracy in a comparison on a wide array of data sets.

Fish community change in Lake Superior, 1970–2000

2003 ◽  
Vol 60 (12) ◽  
pp. 1552-1574 ◽  
Author(s):  
Charles R Bronte ◽  
Mark P Ebener ◽  
Donald R Schreiner ◽  
David S DeVault ◽  
Michael M Petzold ◽  
...  
Keyword(s):  
Great Lakes ◽  
Native Species ◽  
Fish Community ◽  
Lake Trout ◽  
Community Change ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Additional Species ◽  
Community Agencies ◽  
Natural Reproduction

Changes in Lake Superior's fish community are reviewed from 1970 to 2000. Lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) stocks have increased substantially and may be approaching ancestral states. Lake herring (Coregonus artedi) have also recovered, but under sporadic recruitment. Contaminant levels have declined and are in equilibrium with inputs, but toxaphene levels are higher than in all other Great Lakes. Sea lamprey (Petromyzon marinus) control, harvest limits, and stocking fostered recoveries of lake trout and allowed establishment of small nonnative salmonine populations. Natural reproduction supports most salmonine populations, therefore further stocking is not required. Nonnative salmonines will likely remain minor components of the fish community. Forage biomass has shifted from exotic rainbow smelt (Osmerus mordax) to native species, and high predation may prevent their recovery. Introductions of exotics have increased and threaten the recovering fish community. Agencies have little influence on the abundance of forage fish or the major predator, siscowet lake trout, and must now focus on habitat protection and enhancement in nearshore areas and prevent additional species introductions to further restoration. Persistence of Lake Superior's native deepwater species is in contrast to other Great Lakes where restoration will be difficult in the absence of these ecologically important fishes.

Planktivory by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) on microcrustacean zooplankton and dreissenid (Bivalvia: Dreissenidae) veligers in southern Lake Ontario

1995 ◽  
Vol 52 (5) ◽  
pp. 925-935 ◽  
Author(s):  
Edward L. Mills ◽  
Connie Adams ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Edward F. Roseman
Keyword(s):  
Laboratory Experiments ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Field Observations ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Consumption Rates ◽  
South Shore ◽  
Young Of The Year ◽  
Veliger Larvae

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.

Dispersion and Retention of Anadromous Rainbow Smelt (Osmerus mordax) Larvae in the Middle Estuary of the St. Lawrence River

1985 ◽  
Vol 42 (2) ◽  
pp. 332-341 ◽  
Author(s):  
Patrick Quellet ◽  
Julian J. Dodson
Keyword(s):  
Water Mass ◽  
High Tide ◽  
Horizontal Distribution ◽  
Circulation System ◽  
Larval Abundance ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Lawrence Estuary ◽  
Middle Estuary ◽  
St Lawrence River

The vertical and horizontal distribution of anadromous rainbow smelt (Osmerus mordax) larvae from hatching in their natal river to their occupation of nursery areas in the middle estuary of the St. Lawrence River was documented to describe the mechanism responsible for the retention of smelt larvae in this area. Peaks of larval abundance observed downstream of the spawning grounds indicate a 24-h periodicity in hatching and the introduction of larvae into the riverine circulation. No retention of larvae was observed between the spawning ground and the downstream portion of the natal river. Our evidence indicates daytime accumulation of larvae at the mouth of the natal river, possibly resulting from the negative phototaxis exhibited by small smelt larvae. Patches of smelt larvae were incorporated into the St. Lawrence estuarine water mass once every 24 h at night following high tide. The subsequent downstream transport of larvae in the St. Lawrence estuary appears slower than the advection of the water mass due to the tendency of larvae to remain deeper in the water column during ebb tides and to concentrate near the surface during flood tides. Smelt larvae are transported from the south shore to the partially mixed northern portion of the middle estuary which represents the principal zone of larval smelt accumulation. We propose that the vertical displacements exhibited by smelt larvae in combination with the two-layer circulation system of the northern middle estuary results in the retention of smelt larvae in this region.

Advances in Fisheries Bioengineering

2008 ◽  
Keyword(s):  
Common Carp ◽  
Striped Bass ◽  
Flow Rate ◽  
Lepomis Macrochirus ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Test Species ◽  
Wide Range ◽  
Flow Through ◽  
Pair Wise Comparison

Abstract.—Aquatic Filter Barrier (AFB) is a permeable fabric material used to reduce the entrainment of ichthyoplankton at water intakes. To determine the potential for this material to protect a wide range of species, we evaluated the retention and survival of the early life stages of common carp <em>Cyprinus carpio</em>, rainbow smelt <em>Osmerus mordax</em>, white sucker <em>Catostomus commersonii</em>, striped bass <em>Morone saxatilis</em>, and bluegill <em>Lepomis macrochirus </em>exposed to AFB fabric in the laboratory. Twelve flow-through testing apparatuses were used in a closed-loop system to evaluate two flow rates (0.04 L/min/cm2) and 0.08 L/min/cm2) and three sizes of fabric perforation (0.5, 1.0, and 1.5 mm) with each species. The results indicate that, with one exception (pair-wise comparison of bluegill survival between 1.0-mm and 1.5- mm perforations; <em>p </em>= 0.0481), survival of organisms was not significantly correlated (<em>p </em>≤ 0.05) to either flow rate or perforation size. Retention of organisms decreased significantly with increasing flow rate for one species of fish (pair-wise comparison of rainbow smelt between 0.04 and 0.08 L/min/cm<sup>2</sup>; <em>p </em>= 0.0084). In addition, larger perforation sizes resulted in significant decreases in retention for three of the test species (common carp, rainbow smelt, and striped bass; <em>p </em>≤ 0.05). Consequently, the potential effectiveness AFB material is reduced by the use of larger perforation sizes. Provided that the material can be maintained and perforation sizes remain small (0.5 mm), AFB should prevent the entrainment of the majority of the organisms of the species tested in the laboratory.

Historical Changes in Large River Fish Assemblages of the Americas

2005 ◽  
Keyword(s):  
New York ◽  
Dreissena Polymorpha ◽  
Native Species ◽  
Environmental Changes ◽  
Fish Assemblages ◽  
Hudson River ◽  
Osmerus Mordax ◽  
Shoreline Development ◽  
Rainbow Smelt ◽  
River Fish

<em>Abstract.</em>—The main channel of the Hudson River is a tidal estuary from its mouth in New York Harbor to Troy, New York, 247 km upstream. It drains about 35,000 km<sup>2</sup> and is an important navigational, commercial, and recreational system. Since the arrival of European settlers over 400 years ago, it has undergone numerous environmental changes. These changes have included channel maintenance by dredging, wholesale dumping of industrial and domestic wastes, scattered in-basin urbanization and shoreline development, deforestation of the watershed and an increase in agriculture, and water removal for commercial, industrial, and agricultural needs. In addition, the biota of the river has supported commercial and recreational harvesting, exotic species have become established, and habitats have become fragmented, replaced, changed in extent, or isolated. The tidal portion of the Hudson River is among the most-studied water bodies on Earth. We use data from surveys conducted in 1936, the 1970s, the 1980s, and the 1990s to examine changes in fish assemblages and from other sources dating back to 1842. The surveys are synoptic but use a variety of gears and techniques and were conducted by different researchers with different study goals. The scale of our assessment is necessarily coarse. Over 200 species of fish are reported from the drainage, including freshwater and diadromous species, estuarine forms, certain life history stages of primarily marine species, and marine strays. The tidal Hudson River fish assemblages have responded to the environmental changes of the last century in several ways. Several important native species appear to be in decline (e.g., rainbow smelt <em>Osmerus mordax </em>and Atlantic tomcod <em>Microgadus tomcod</em>), others, once in decline, have rebounded (e.g., striped bass <em>Morone saxatilis</em>), and populations of some species seem stable (e.g., spottail shiner <em>Notropis hudsonius</em>). No native species is extirpated from the system, and only one, shortnose sturgeon <em>Acipenser brevirostrum</em>, is listed as endangered. The recent establishment of the exotic zebra mussel <em>Dreissena polymorpha </em>may be shifting the fish assemblage away from openwater fishes (e.g., <em>Alosa</em>) and toward species associated with vegetation (e.g., centrarchids). In general, the Hudson River has seen an increase in the number and importance of alien species and a change in dominant species.

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