Persistent disturbance by commercial navigation alters the relative abundance of channel-dwelling fishes in a large river

2006 ◽  
Vol 63 (11) ◽  
pp. 2418-2433 ◽  
Author(s):  
Steve Gutreuter ◽  
Jon M Vallazza ◽  
Brent C Knights
Keyword(s):  
Relative Abundance ◽  
Ictalurus Punctatus ◽  
Mississippi River ◽  
Model Averaging ◽  
Information Criterion ◽  
Abundant Species ◽  
Large River ◽  
Dorosoma Cepedianum ◽  
White Bass ◽  
Intensively Managed

We provide the first evidence for chronic effects of disturbance by commercial vessels on the spatial distribution and abundance of fishes in the channels of a large river. Most of the world's large rivers are intensively managed to satisfy increasing demands for commercial shipping, but little research has been conducted to identify and alleviate any adverse consequences of commercial navigation. We used a combination of a gradient sampling design incorporating quasicontrol areas with Akaike's information criterion (AIC)-weighted model averaging to estimate effects of disturbances by commercial vessels on fishes in the upper Mississippi River. Species density, which mainly measured species evenness, decreased with increasing disturbance frequency. The most abundant species — gizzard shad (Dorosoma cepedianum) and freshwater drum (Aplodinotus grunniens) — and the less abundant shovelnose sturgeon (Scaphirhynchus platorhynchus) and flathead catfish (Pylodictis olivaris) were seemingly unaffected by traffic disturbance. In contrast, the relative abundance of the toothed herrings (Hiodon spp.), redhorses (Moxostoma spp.), buffaloes (Ictiobus spp.), channel catfish (Ictalurus punctatus), sauger (Sander canadensis), and white bass (Morone chrysops) decreased with increasing traffic in the navigation channel. We hypothesized that the combination of alteration of hydraulic features within navigation channels and rehabilitation of secondary channels might benefit channel-dependent species.

Historical Changes in Large River Fish Assemblages of the Americas

2005 ◽  
Keyword(s):  
Relative Abundance ◽  
Mississippi River ◽  
Largemouth Bass ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Micropterus Salmoides ◽  
Lepomis Macrochirus ◽  
Large River ◽  
Frequency Of Occurrence ◽  
Abundance And Distribution

<em>Abstract.</em>—An investigation of historical fisheries information for pools 4–13 of the upper Mississippi River (UMR) was conducted to 1) determine the pre-1938 relative abundance and distribution of bluegill <em>Lepomis macrochirus </em>and largemouth bass <em>Micropterus salmoides, </em>2) determine the composition and relative abundance of the preimpoundment fish assemblage, and 3) determine if a shift in frequency of occurrence and relative abundance has occurred due to impoundment.

Feeding Ecology of the Sauger (Stizostedion canadense) in a Large River

1985 ◽  
Vol 42 (1) ◽  
pp. 120-128 ◽  
Author(s):  
David H. Wahi ◽  
Larry A. Nielsen
Keyword(s):  
Food Consumption ◽  
Ictalurus Punctatus ◽  
Extended Period ◽  
Large River ◽  
The Body ◽  
Ohio River ◽  
Dorosoma Cepedianum ◽  
Aplodinotus Grunniens ◽  
Stizostedion Canadense ◽  
Annual Period

In stomachs of 550 sauger (Stizostedion canadense) collected by gillnetting in the Ohio River during June 1980 through August 1981, Dorosoma cepedianum were the most abundant prey (42% of all identified prey), followed by Notropis atherinoides (28%), Aplodinotus grunniens (16%), and Ictalurus punctatus (12%). Annual food consumption of sauger averaged 1.1% of the body weight per day. Growth and daily ration followed similar patterns, being high from September to January (maximum in October) and low from March to August. Rapid growth and high food consumption throughout fall and early winter were related to an extended period of high temperatures and increased availability of Dorosoma cepedianum. The annual period of growth and food consumption was longer and peaked later in the year in the river than those previously observed in other types of aquatic systems.

scholarly journals Extrapolating Parametric Survival Models in Health Technology Assessment Using Model Averaging: A Simulation Study

2021 ◽  
Vol 41 (4) ◽  
pp. 476-484
Author(s):  
Daniel Gallacher ◽  
Peter Kimani ◽  
Nigel Stallard
Keyword(s):  
Survival Time ◽  
Survival Data ◽  
Mean Squared Error ◽  
Model Averaging ◽  
Information Criterion ◽  
Health Technology ◽  
Weighted Averaging ◽  
Health Technologies ◽  
Mean Survival Time ◽  
Restricted Mean Survival Time

Previous work examined the suitability of relying on routine methods of model selection when extrapolating survival data in a health technology appraisal setting. Here we explore solutions to improve reliability of restricted mean survival time (RMST) estimates from trial data by assessing model plausibility and implementing model averaging. We compare our previous methods of selecting a model for extrapolation using the Akaike information criterion (AIC) and Bayesian information criterion (BIC). Our methods of model averaging include using equal weighting across models falling within established threshold ranges for AIC and BIC and using BIC-based weighted averages. We apply our plausibility assessment and implement model averaging to the output of our previous simulations, where 10,000 runs of 12 trial-based scenarios were examined. We demonstrate that removing implausible models from consideration reduces the mean squared error associated with the restricted mean survival time (RMST) estimate from each selection method and increases the percentage of RMST estimates that were within 10% of the RMST from the parameters of the sampling distribution. The methods of averaging were superior to selecting a single optimal extrapolation, aside from some of the exponential scenarios where BIC already selected the exponential model. The averaging methods with wide criterion-based thresholds outperformed BIC-weighted averaging in the majority of scenarios. We conclude that model averaging approaches should feature more widely in the appraisal of health technologies where extrapolation is influential and considerable uncertainty is present. Where data demonstrate complicated underlying hazard rates, funders should account for the additional uncertainty associated with these extrapolations in their decision making. Extended follow-up from trials should be encouraged and used to review prices of therapies to ensure a fair price is paid.

scholarly journals Trouble in Paradise? A comparison of 1953 and 2005 benthonic foraminiferal seafloor assemblages at the Ibis Field, offshore eastern Trinidad, West Indies

2006 ◽  
Vol 25 (2) ◽  
pp. 157-164 ◽  
Author(s):  
Brent Wilson
Keyword(s):  
Relative Abundance ◽  
Nutrient Enrichment ◽  
Abundant Species ◽  
Nutrient Supply ◽  
South American ◽  
Sufficient Time ◽  
Phytoplankton Primary Production ◽  
Environmental Perturbations ◽  
Run Off ◽  
Shrimp Farms

Abstract. Foraminiferal communities are not static, but change in response to environmental perturbations. Given sufficient time, the change will be recorded in the total (live+dead) seafloor assemblage, from which valuable information regarding environmental trends can be obtained by re-sampling assemblages at the decadal scale.The seafloor assemblage in the 5 km × 6 km Ibis Field, off southeast Trinidad, first surveyed in 1953, was re-examined in 2005. The fauna had changed markedly between the surveys. Overall increases in the proportional abundances of Uvigerina subperegrina, Ammonia pauciloculata/Rolhausenia rolhauseni and Pseudononion atlanticum indicate an increase in nutrient supply that apparently killed off Cibicidoides pseudoungerianus and Miliolinella subrotunda, and reduced the relative abundance of Hanzawaia concentrica, but did not affect the relative abundance of Cancris sagrai. As shown by similar 1953 and 2005 planktonic/benthonic foraminiferal ratios, the increased nutrient supply impacted on both surface and bottom waters.Of the six most abundant species in 2005, five showed the same general biogeographical distributions within the field in 1953 and 2005. However, whereas the proportional abundance of Uvigerina subperegrina in 1953 increased southwards, in 2005 it increased northwards.Trinidad cannot be the source for the nutrient enrichment: the island lies down-current from the Ibis Field. Sources must therefore be sought up-current and to the southeast, in the Amazon, Essequibo and Orinoco river basins, or along the South American shoreline. It is speculated that the nutrient enrichment may be a consequence of increased phytoplankton primary production associated with nitrogen-rich run-off from South American sugarcane plantations, or from flushing of organic carbon from poorly regulated sewage systems or shrimp farms in South America.

Effect of fire regime on the grass community of the humid savanna of Lamto, Ivory Coast

2018 ◽  
Vol 35 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Kouamé Fulgence Koffi ◽  
Aya Brigitte N’Dri ◽  
Jean-Christophe Lata ◽  
Souleymane Konaté ◽  
Tharaniya Srikanthasamy ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Ivory Coast ◽  
Fire Regime ◽  
Fire Regimes ◽  
Abundant Species ◽  
Grass Species ◽  
The Third ◽  
Humid Savanna ◽  
The Impact ◽  
Tussock Grasses

AbstractThis study assesses the impact of four fire treatments applied yearly over 3 y, i.e. early fire, mid-season fire, late fire and no fire treatments, on the grass communities of Lamto savanna, Ivory Coast. We describe communities of perennial tussock grasses on three replicated 5 × 5-m or 10 × 5-m plots of each fire treatment. Tussock density did not vary with fire treatment. The relative abundance of grass species, the circumference of grass tussocks and the probability of having a tussock with a central die-back, varied with fire treatment. Mid-season fire had the highest proportion of tussocks with a central die-back while the late fire had the smallest tussocks. Tussock density, circumference, relative abundance and probability of having a central die-back varied with species. Andropogon canaliculatus and Hyparrhenia diplandra were the most abundant of the nine grass species. They had the largest tussocks and the highest proportion of tussock with a central die-back. Loudetia simplex was the third most abundant species but was very rare in no fire plots. The distribution of tussock circumferences was right skewed and dominated by small tussocks. The proportion of the tussocks with a central die-back strongly increased with circumference, which could lead to tussock fragmentation. Taken together, this study suggests that fire regimes impact grass demography and that this impact depends on grass species and tussock size.

scholarly journals Hydrology controls recruitment of two invasive cyprinids: bigheaded carp reproduction in a navigable large river

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3641 ◽  
Author(s):  
Daniel K. Gibson-Reinemer ◽  
Levi E. Solomon ◽  
Richard M. Pendleton ◽  
John H. Chick ◽  
Andrew F. Casper
Keyword(s):  
Mississippi River ◽  
Silver Carp ◽  
Monitoring Program ◽  
Large River ◽  
Asian Carp ◽  
Bighead Carp ◽  
Illinois River ◽  
Hypophthalmichthys Molitrix ◽  
The Past ◽  
Causative Factors

In the Mississippi River Basin of North America, invasive bigheaded carp (silver carpHypophthalmichthys molitrixand bighead carpH. nobilis, also referred to as Asian carp) have spread rapidly over the past several decades. In the Illinois River, an important tributary of the Upper Mississippi River, reproduction appears to be sporadic and frequently unsuccessful, yet bigheaded carp densities in this river are among the highest recorded on the continent. Understanding the causative factors behind erratic recruitment in this commercially-harvested invasive species is important for both limiting their spread and managing their harvest. We analyzed weekly catch records from 15 years of a standardized monitoring program to document the emergence of age-0 bigheaded carp in relation to environmental conditions. The appearance of age-0 fish was generally linked to hydrographic attributes, which probably serve as a cue for spawning. However, we found profound differences in the number of age-0 fish among years, which varied by as much as five orders of magnitude in successive years. The strong link between summer flooding and age-0 fish production we observed emphasizes the importance of understanding the hydrologic context in which sustained invasions occur. Despite evidence of sporadic recruitment, bigheaded carp populations in the Illinois River appear to be consistent or increasing because of particularly strong, episodic year classes.

Biology and Management of Inland Striped Bass and Hybrid Striped Bass

2013 ◽  
Keyword(s):  
Striped Bass ◽  
The United States ◽  
Minimum Length ◽  
State Agencies ◽  
Hybrid Striped Bass ◽  
White Bass ◽  
Regulatory Strategies ◽  
Intensively Managed ◽  
Catch Rates ◽  
Sport Fish

<em>Abstract</em>.—Inland populations of striped bass <em>Morone saxatilis </em>and hybrid striped bass (white bass <em>M. chrysops </em>× striped bass) are intensively managed across the United States for their recreational value using a variety of regulations; however, the full extent of different regulatory strategies is unknown. This paper describes regulations used by states to manage their inland striped bass and hybrid striped bass fisheries. An Internet-based survey seeking information on issues such as stocking dependency, trophy potential, catch rates, and statewide and specialized regulations for both striped bass and hybrid striped bass fisheries was created and distributed to all state agencies. The survey found that 32 states have inland populations of striped bass, hybrid striped bass, or both. Daily creel limits for striped bass and hybrid striped bass ranged from 2 to 30; the most liberal creel limits were found in southern states. Half of the states reported that their statewide length limit for both taxa has few or no exceptions for conditions in particular water bodies, and 85% of states with striped bass and 92% of states with hybrid striped bass enforce a minimum length limit as their statewide length limit. Although both taxa were generally managed with similar regulations, striped bass were usually considered a more important sport fish species and were managed more intensively than hybrid striped bass. A literature review confirmed that little research has been published on the response (or lack thereof) of striped bass and their hybrids to any of the various management schemes reported herein.

Étude des relations entre les communautés piscicoles et les différents habitats d'une rivière nordique: notion d'habitat optimal

1982 ◽  
Vol 60 (12) ◽  
pp. 3344-3352
Author(s):  
Louise Savard ◽  
Guy Moreau
Keyword(s):  
Relative Abundance ◽  
Condition Factor ◽  
Northern Pike ◽  
Abundant Species ◽  
The Other ◽  
Coregonus Clupeaformis ◽  
Habitat Types ◽  
Linkage Cluster ◽  
Complete Linkage Cluster ◽  
Satellite Species

A complete linkage cluster analysis using the physical characteristics of the sampling sites has revealed the existence of five groups corresponding to five habitat types nonequally distributed in a northern Quebec river. According to the results of discriminant analysis using the relative abundance of the fish species present, these habitats support populations which differ by the relative abundance of species and not by the presence or absence of some particular species. A habitat is first characterized by a species living preferentially in this habitat, then by the other species inhabiting the area in an opportunistic way, and finally by some satellite species which do not seem to have any marked requirements. A habitat is considered as optimal for a species first if this species inhabits this area preferentially to others and secondly if this use is more advantageous for growth or condition factor. This seems to be confirmed for two of the most abundant species, northern pike (Esox lucius) and lake whitefish (Coregonus clupeaformis), both of which have a higher condition factor and a better growth in the part of the river where their optimal habitat is more frequently found.

scholarly journals Winter bird numbers and land-use preferences in an arable landscape in eastern England

1999 ◽  
Vol 9 (2) ◽  
pp. 119-127 ◽  
Author(s):  
Christopher F. Mason ◽  
Sheila M. Macdonald
Keyword(s):  
Habitat Preferences ◽  
Abundant Species ◽  
Winter Period ◽  
Alauda Arvensis ◽  
Bird Populations ◽  
Winter Cereals ◽  
Arable Farmland ◽  
Intensively Managed ◽  
Agricultural Extensification ◽  
Tilled Land

SummaryThe winter bird assemblage and habitat preferences were studied in a largely arable landscape, dominated by winter cereals, in eastern England in one winter. A total of species was recorded on 70 l-km transects but 11% of transects had no birds. Overall densities were low, Skylark Alauda arvensis being the most abundant species. Bird was highest in the first winter period (October-December). Species richness varied proportion to the available habitat in the first winter period but there was a preference for stubble, grass and tilled land (harrow) in the second winter period (January-February) Skylarks preferred stubbles in the first winter period and stubbles and grass in the second winter period. Some 34% of all birds fed on winter cereals despite a lack of preference for this habitat, while 94% of seed specialists (finches and buntings) were recorded on stubbles. The areas of preferred habitats (stubbles, grass) were probably too limited to allow more than small populations to persist. Only by the widespread adoption of agricultural extensification and/or farming some of the land specifically for conservation benefits can the declines in bird populations on intensively managed arable farmland be reversed.

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