scholarly journals Size-Dependent Trophic Patterns of Pallid Sturgeon and Shovelnose Sturgeon in a Large River System

2013 ◽  
Vol 4 (1) ◽  
pp. 41-52 ◽  
Author(s):  
William E. French ◽  
Brian D. S. Graeb ◽  
Katie N. Bertrand ◽  
Steven R. Chipps ◽  
Robert A. Klumb
Keyword(s):  
South Dakota ◽  
Trophic Position ◽  
Fork Length ◽  
Missouri River ◽  
River System ◽  
Large River ◽  
Diet Shift ◽  
Fish Prey ◽  
Shovelnose Sturgeon ◽  
Pallid Sturgeon

Abstract This study compared patterns of δ15N and δ13C enrichment of pallid sturgeon Scaphirhynchus albus and shovelnose sturgeon S. platorynchus in the Missouri River, United States, to infer their trophic position in a large river system. We examined enrichment and energy flow for pallid sturgeon in three segments of the Missouri River (Montana/North Dakota, Nebraska/South Dakota, and Nebraska/Iowa) and made comparisons between species in the two downstream segments (Nebraska/South Dakota and Nebraska/Iowa). Patterns in isotopic composition for pallid sturgeon were consistent with gut content analyses indicating an ontogenetic diet shift from invertebrates to fish prey at sizes of >500-mm fork length (FL) in all three segments of the Missouri River. Isotopic patterns revealed shovelnose sturgeon did not experience an ontogenetic shift in diet and used similar prey resources as small (<500-mm FL) pallid sturgeon in the two downstream segments. We found stable isotope analysis to be an effective tool for evaluating the trophic position of sturgeons within a large river food web.

HUMAN ALTERATIONS TO LANDSCAPE CONNECTIVITY AND LARGE-RIVER BIOTA: PALLID STURGEON IN THE MISSOURI RIVER

2018 ◽  
Author(s):  
Robert B. Jacobson ◽  
◽  
Susannah O. Erwin ◽  
Caroline M. Elliott ◽  
Edward A. Bulliner ◽  
...  
Keyword(s):  
Landscape Connectivity ◽  
Missouri River ◽  
Large River ◽  
Pallid Sturgeon

Distribution and trophic dynamics of riparian tetragnathid spiders in a large river system

2016 ◽  
Vol 67 (3) ◽  
pp. 309 ◽  
Author(s):  
Paradzayi Tagwireyi ◽  
S. Mažeika P. Sullivan
Keyword(s):  
Aquatic Insects ◽  
Trophic Position ◽  
River System ◽  
Benthic Algae ◽  
Terrestrial Ecosystems ◽  
Large River ◽  
Trophic Dynamics ◽  
Rural Landscapes ◽  
Small Streams ◽  
Insect Density

Development and agriculture are increasingly encroaching into riparian areas, with largely unknown effects on nearshore arthropods, which are important components of linked aquatic–terrestrial food webs. To assess the environmental determinants of the distribution and trophic dynamics of riparian spiders of the family Tetragnathidae, we characterised riparian habitat, collected emergent aquatic insects, and surveyed spiders in developed and rural landscapes of the Scioto River system, Ohio, USA, which provided a range of riparian land cover, nearshore vegetation types and habitat complexity. We also estimated the trophic position (TP) of Tetragnathidae and the proportion of energetic and nutritional subsidies derived from benthic algae (EBA) using naturally abundant carbon (C) and nitrogen (N) stable isotopes. Model-selection results revealed that tetragnathid spider density (1.57–3.80individualsm–1) was more sensitive to differences in overhanging vegetation than to those in aquatic food resources (i.e. emergent aquatic insects). Tetragnathidae TP, which averaged 3.16 across all 12 study reaches (range: 2.35–3.98), was largely driven by canopy density, shoreline shape, percentage overhanging vegetation and emergent-insect density. Emergent-insect density was the strongest driver of tetragnathid spider EBA (0.04–0.54, µ=0.24). Our study reinforced the notion that riparian spiders ecologically link aquatic and terrestrial ecosystems. In particular, our results further current understanding of the mechanisms affecting riparian spider distribution and trophic dynamics, particularly in the context of larger stream and river systems, given that the propensity of related research has occurred in small streams.

Range-wide age and growth characteristics of shovelnose sturgeon from mark–recapture data: implications for conservation and management

2015 ◽  
Vol 72 (1) ◽  
pp. 71-82 ◽  
Author(s):  
Martin J. Hamel ◽  
Mark A. Pegg ◽  
Reuben R. Goforth ◽  
Quinton E. Phelps ◽  
Kirk D. Steffensen ◽  
...  
Keyword(s):  
River Basin ◽  
Mississippi River ◽  
Missouri River ◽  
Large River ◽  
Population Connectivity ◽  
Growth Characteristics ◽  
Age And Growth ◽  
Mark Recapture ◽  
Shovelnose Sturgeon ◽  
Commercial Harvest

We used mark–recapture data from shovelnose sturgeon (Scaphirhynchus platorynchus) to describe range-wide growth characteristics and developed a model to estimate ages. Data were solicited throughout much of the current distribution of shovelnose sturgeon, specifically from the mainstem Missouri and Mississippi rivers and their tributaries. Shovelnose sturgeon exhibited variable growth among locations; however, adult fish exhibited almost no growth after they reached a particular size, presumably the size at sexual maturity. Shovelnose sturgeon from the Mississippi River basin attained greater maximum sizes and ages compared with the Missouri River basin. However, two populations from the Mississippi River that received high exploitation from commercial harvest had truncated age distributions with smaller asymptotic lengths. Lower Missouri River populations were characteristic of exploited populations (i.e., smaller fish and reduced longevity), presumably a result of anthropogenic effects. Wide discrepancies in maximum age and size suggest shovelnose sturgeon are capable of displaying phenotypic plasticity in response to exploitation or environmental influences. Determining metapopulation dynamics is a priority because it is unknown how population connectivity may influence dynamic rate functions and persistence of large-river fishes. Identifying potential source–sink connections in terms of population dynamics may provide a template for direction of future restoration and recovery efforts.

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