Reproductive characteristics of the ruffe, Gymnocephalus cernuus, in the St. Louis River estuary on western Lake Superior: a histological examination of the ovaries over one annual cycle

1997 ◽  
Vol 54 (2) ◽  
pp. 256-263 ◽  
Author(s):  
R L Leino ◽  
J H McCormick
Keyword(s):  
Histological Examination ◽  
Annual Cycle ◽  
Lake Superior ◽  
River Estuary ◽  
Gymnocephalus Cernuus ◽  
Reproductive Characteristics ◽  
Western Lake

Larval identification of the ruffe, Gymnocephalus cernuus (Linnaeus) (Percidae: Percini), in the St. Louis River Estuary, Lake Superior drainage basin, Minnesota

1991 ◽  
Vol 69 (2) ◽  
pp. 436-442 ◽  
Author(s):  
Thomas P. Simon ◽  
Joe T. Vondruska
Keyword(s):  
North America ◽  
Yellow Perch ◽  
Drainage Basin ◽  
Lake Superior ◽  
River Estuary ◽  
Swim Bladder ◽  
Species Occurrence ◽  
Caudal Peduncle ◽  
Gymnocephalus Cernuus ◽  
Native North American

A reproducing population of the Eurasian percid Gymnocephalus cernuus was discovered in the St. Louis River, Lake Superior basin, near Duluth, Minnesota. This study is the first documented evidence of the species occurrence and reproduction in North America. Larvae resemble typical percids and are described with emphasis on meristic, morphometric, and pigmentary characters. Ruffe are distinguished from all native North American percids by the presence of a slightly concave head becoming attenuated at larger length intervals, a pointed snout with teeth on the maxillary and premaxillary by the time a length of 11 mm is reached, a large dorsally pigmented swim bladder, a serrated preopercle, and few postanal myomeres (usually 18–22). In particular, ruffe superficially resemble johnny darters as yolk-sac larvae, and walleye, yellow perch, and logperch at lengths greater than 10 mm, but can be distinguished by the previously mentioned characteristics and a deep shoulder depth and a narrow caudal peduncle.

Estimating Sediment and Nutrient Loads in Four Western Lake Superior Streams

2014 ◽  
Vol 50 (5) ◽  
pp. 1138-1154 ◽  
Author(s):  
Elaine M. Ruzycki ◽  
Richard P. Axler ◽  
George E. Host ◽  
Jerald R. Henneck ◽  
Norman R. Will
Keyword(s):  
Lake Superior ◽  
Nutrient Loads ◽  
Western Lake

The effect of a flood pulse on the water column of western Lake Superior, USA

2014 ◽  
Vol 40 (2) ◽  
pp. 455-462 ◽  
Author(s):  
Elizabeth C. Minor ◽  
Brandy Forsman ◽  
Stephanie J. Guildford
Keyword(s):  
Water Column ◽  
Lake Superior ◽  
Flood Pulse ◽  
Western Lake

scholarly journals Regional, watershed, and site-specific environmental influences on fish assemblage structure and function in western Lake Superior tributaries

2005 ◽  
Vol 62 (6) ◽  
pp. 1254-1270 ◽  
Author(s):  
John C Brazner ◽  
Danny K Tanner ◽  
Naomi E Detenbeck ◽  
Sharon L Batterman ◽  
Stacey L Stark ◽  
...  
Keyword(s):  
Fish Assemblage ◽  
Brook Trout ◽  
Fish Assemblages ◽  
Lake Superior ◽  
Structure And Function ◽  
Assemblage Structure ◽  
Fish Assemblage Structure ◽  
Site Specific ◽  
Western Lake ◽  
And Function

The relative importance of regional, watershed, and in-stream environmental factors on fish assemblage structure and function was investigated in western Lake Superior tributaries. We selected 48 second- and third-order watersheds from two hydrogeomorphic regions to examine fish assemblage response to differences in forest fragmentation, watershed storage, and a number of other watershed, riparian, and in-stream habitat conditions. Although a variety of regional, fragmentation, and storage-related factors had significant influences on the fish assemblages, water temperature appeared to be the single most important environmental factor. We found lower water temperatures and trout–sculpin assemblages at lower fragmentation sites and higher temperatures and minnow–sucker–darter assemblages as storage increased. Factors related to riparian shading and flow separated brook trout streams from brown trout (Salmo trutta) – rainbow trout (Oncorhynchus mykiss) streams. Functionally, fish assemblages at lower fragmentation sites were dominated by cold-water fishes that had low silt tolerance and preferred moderate current speeds, while fishes with higher silt tolerances, warmer temperature preferences, and weaker sustained swimming capabilities were most common at higher storage sites. Our results suggest that site-specific environmental conditions are highly dependent on regional- and watershed-scale characters and that a combination of these factors operates in concert to influence the structure and function of stream fish assemblages.

Enhanced Removal of Hydrophobic Organic Contaminants by Settling Sediments in Western Lake Superior

2003 ◽  
Vol 29 (1) ◽  
pp. 41-53 ◽  
Author(s):  
Matt F. Simcik ◽  
Jeff D. Jeremiason ◽  
Elizabeth Lipiatou ◽  
Steven J. Eisenreich
Keyword(s):  
Organic Contaminants ◽  
Lake Superior ◽  
Hydrophobic Organic Contaminants ◽  
Western Lake

Swan grazing on seagrass: abundance but not grazing pressure varies over an annual cycle in a temperate estuary

2014 ◽  
Vol 65 (8) ◽  
pp. 738 ◽  
Author(s):  
Gary E. Choney ◽  
Kathryn McMahon ◽  
Paul S. Lavery ◽  
Neil Collier
Keyword(s):  
Annual Cycle ◽  
River Estuary ◽  
Grazing Pressure ◽  
Food Sources ◽  
Spatial And Temporal Variation ◽  
Human Disturbances ◽  
Black Swans ◽  
New Findings ◽  
Cycle Maximum ◽  
Negative Effect

Herbivorous waterfowl such as black swans are significant grazers in temperate waterbodies; their abundance, distribution and grazing rates vary over seasonal cycles. The present study examined spatial and temporal variation in the abundance and grazing rates of black swans in the Lower Swan River estuary, Western Australia, using visual surveys over 1 year (2009), and potential drivers of this variation, food sources and disturbance factors were assessed. We predicted that swan abundance and grazing pressure would be greater in summer and autumn when seasonal wetlands dry and the abundance of food sources would positively influence their distribution, whereas the level of disturbance would have a negative effect. Plant–grazer interactions are dynamic and complex; the present study revealed new findings on the seasonality of this relationship, where swan abundance but not grazing pressure varied over an annual cycle. Maximum swan abundance occurred in autumn (185) with minima in spring (53) but the swan grazing pressure did not vary between seasons, ranging from 6% to 25% of seagrass production consumed. Swan abundance was a function of season and the cover of seagrass. Key hot spots for swan abundance were identified where management efforts could be targeted by minimising human disturbances and protecting seagrass.

Sign in / Sign up

Export Citation Format

Share Document