Gammarus lawrencianus (Amphipoda) as Intermediate Host of Echinorhynchus salmonis (Acanthocephala) in an Estuarine Environment

1993 ◽  
Vol 50 (10) ◽  
pp. 2182-2184 ◽  
Author(s):  
Lena N. Measures ◽  
Luci Bossé
Keyword(s):  
North America ◽  
Intermediate Host ◽  
Estuarine Environment ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
First Report ◽  
St Lawrence River

Echinorhynchus salmonis (Acanthocephala) were found in the stomach of a rainbow smelt, Osmerus mordax (Salmoniformes), collected at the confluence of the Aux-Outardes River and St. Lawrence River in Quebec. One acanthocephalan occupied the haemocoel of a recently ingested amphipod (Gammarus lawrencianus), while two other specimens were free in the stomach. This is the first report of G. lawrencianus, an estuarine amphipod, as intermediate host of E. salmonis. This is also the first report of transmission of E. salmonis in an estuarine environment in North America.

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.

Waterfowl mortality caused by Cyathocotyle bushiensis Khan, 1962 (Trematoda: Cyathocotylidae), St. Lawrence River, Quebec

1972 ◽  
Vol 50 (11) ◽  
pp. 1351-1356 ◽  
Author(s):  
G. G. Gibson ◽  
E. Broughton ◽  
L. P. E. Choquette
Keyword(s):  
North America ◽  
First Record ◽  
First Report ◽  
Anas Rubripes ◽  
Breeding Populations ◽  
Waterfowl Mortality ◽  
St Lawrence River ◽  
Cyathocotyle Bushiensis

In St. Lawrence River marshes, fatal sporadic and epizootic typhlitis in breeding populations of black ducks, Anas rubripes; blue-winged teal, A. discors; and migrant green-winged teal, A. carolinensis, is attributed to Cyathocotyle bushiensis Khan, 1962. This is the first report of C. bushiensis in natural definitive hosts, and the first record of the genus Cyathocotyle in North America. Pathogenicity of C. bushiensis was confirmed experimentally by using metacercariae from the most abundant local gastropod, Bythinia tentaculata, to produce cyathocotyliasis in Pekin ducklings.

A mtDNA analysis of spatiotemporal distribution of two sympatric larval populations of rainbow smelt (Osmerus mordax) in the St. Lawrence River estuary, Quebec, Canada

1998 ◽  
Vol 55 (7) ◽  
pp. 1739-1747 ◽  
Author(s):  
Dany Pigeon ◽  
Julian J Dodson ◽  
Louis Bernatchez
Keyword(s):  
Resource Partitioning ◽  
River Estuary ◽  
Osmerus Mordax ◽  
Relative Distribution ◽  
Sympatric Populations ◽  
Rainbow Smelt ◽  
Genetic Population ◽  
Spatial Homogeneity ◽  
Middle Estuary ◽  
St Lawrence River

Ecological isolation through resource partitioning is invoked as a major factor for explaining the persistence of genetically distinct yet closely related sympatric populations. Two genetically distinct sympatric populations of anadromous rainbow smelt (Osmerus mordax) exist in the middle estuary of the St. Lawrence River. The persistence of these coexisting populations in sympatry is in conflict with current theoretical concepts predicting population richness. In the present study, we performed mtDNA PCR-RFLP analysis of 922 larvae from 33 sampling stations to test the hypothesis that the larvae belonging to the two sympatric smelt populations of the St. Lawrence middle estuary are spatially segregated and that such segregation may promote the persistence of the populations. Results clearly revealed spatial homogeneity in the relative distribution of larvae from the two populations. Consequently, they did not support our working hypothesis that larvae belonging to the two sympatric smelt populations are spatially segregated. Two alternative explanations may account for the lack of spatial partitioning observed here. Competition may not be important enough to promote resource partitioning at the larval stage. Alternatively, resource partitioning occurs, but not spatially. This study also demonstrated that the effect of historical events may have been as important as contemporary ecological settings in determining genetic population structure in smelt.

Early Maize in Northeastern North America: A Comment on Emerson and Colleagues

2021 ◽  
Vol 86 (2) ◽  
pp. 425-427
Author(s):  
John P. Hart ◽  
William A. Lovis ◽  
M. Anne Katzenberg
Keyword(s):  
North America ◽  
Great Lakes ◽  
Empirical Evidence ◽  
River Valley ◽  
Human Bone ◽  
Northeastern North America ◽  
Isotopic Evidence ◽  
St Lawrence River

Emerson and colleagues (2020) provide new isotopic evidence on directly dated human bone from the Greater Cahokia region. They conclude that maize was not adopted in the region prior to AD 900. Placing this result within the larger context of maize histories in northeastern North America, they suggest that evidence from the lower Great Lakes and St. Lawrence River valley for earlier maize is “enigmatic” and “perplexing.” Here, we review that evidence, accumulated over the course of several decades, and question why Emerson and colleagues felt the need to offer opinions on that evidence without providing any new contradictory empirical evidence for the region.

First report of Angiostrongylus vasorum in coyotes in mainland North America

2018 ◽  
Vol 183 (24) ◽  
pp. 747-747 ◽  
Author(s):  
Jenna Marie Priest ◽  
Donald T Stewart ◽  
Michael Boudreau ◽  
Jason Power ◽  
Dave Shutler
Keyword(s):  
North America ◽  
Angiostrongylus Vasorum ◽  
First Report

First Report of Powdery Mildew of Lycium chinense (Chinese Matrimony Vine) Caused by Arthrocladiella mougeotii in the Pacific Northwest

2004 ◽  
Vol 5 (1) ◽  
pp. 16
Author(s):  
Dean A. Glawe
Keyword(s):  
North America ◽  
Powdery Mildew ◽  
Medicinal Plant ◽  
Pacific Northwest ◽  
Morphological Features ◽  
Lycium Chinense ◽  
First Report ◽  
Landscape Plant ◽  
The Pacific ◽  
Plant Grown

Chinese matrimony-vine (Lycium chinense Mill.) is a traditional medicinal plant grown in China and used as a perennial landscape plant in North America. This report documents the presence of powdery mildew on L. chinense in the Pacific Northwest and describes and illustrates morphological features of the causal agent. It appears to be the first report of a powdery mildew caused by Arthrocladiella in the Pacific Northwest. Accepted for publication 10 November 2004. Published 8 December 2004.

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.

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