Phytoplankton assemblages in the St. Lawrence River, downstream of its confluence with the Ottawa River, Quebec, Canada

2000 ◽  
Vol 57 (S1) ◽  
pp. 16-30 ◽  
Author(s):  
Christiane Hudon
Keyword(s):  
Great Lakes ◽  
Water Clarity ◽  
Phytoplankton Assemblages ◽  
River Waters ◽  
Taxa Richness ◽  
Ottawa River ◽  
Water Characteristics ◽  
Biological Impacts ◽  
Lower Biomass ◽  
St Lawrence River

Consistent differences in physical, chemical, and biological characteristics were observed along a transversal river section located 2 km downstream of the confluence of the Ottawa and the St. Lawrence rivers. Phytoplankton sampled at stations subject to the influence of the St. Lawrence River had a lower biomass, smaller cell volume, lower chlorophyll a, and lower taxa richness than did phytoplankton at stations influenced by the Ottawa River. The stations influenced by St. Lawrence River waters showed regular seasonal changes in phytoplankton biomass and composition, reflecting the major impact of the stratification and mixing cycles observed in the Great Lakes. By comparison, at the stations influenced by Ottawa River waters, monthly variations were found in biomass and composition correlated with temperature and water clarity, suggesting the effects of the watershed's morphology. A discharge reduction of 12% in the St. Lawrence River and 46% in the Ottawa River between summer 1994 and summer 1995 coincided, for stations in both water masses, with lower biomass and greater species richness and an increase in taxa that generate noxious smells and odours. Phytoplankton is recommended for use in monitoring the biological impacts of changes in water characteristics resulting from human activities and climate change in the Great Lakes watershed.

scholarly journals Eurasian tench (Tinca tinca): the next Great Lakes invader

2018 ◽  
Vol 75 (2) ◽  
pp. 169-179 ◽  
Author(s):  
Sunčica Avlijaš ◽  
Anthony Ricciardi ◽  
Nicholas E. Mandrak
Keyword(s):  
Great Lakes ◽  
Algal Growth ◽  
Water Clarity ◽  
Ecological Impacts ◽  
Commercial Fishing ◽  
Tinca Tinca ◽  
Benthic Fishes ◽  
Tench Tinca Tinca ◽  
Natural Dispersal ◽  
St Lawrence River

A globally invasive fish, Eurasian tench (Tinca tinca) is spreading through the St. Lawrence River and poses an imminent invasion threat to the Great Lakes. Following its illegal release into a tributary of the St. Lawrence River in 1991, tench has spread throughout the river’s main stem over the past decade, and its abundance in commercial fishing bycatch in the river has grown exponentially. The tench is a generalist benthic consumer with largely undocumented ecological impacts in North America. Reports from other invaded regions indicate that it can compete with other benthic fishes, host a diverse assemblage of parasites and pathogens, degrade water clarity in shallow lakes, limit submerged macrophyte growth, reduce gastropod populations, and promote benthic algal growth through top-down effects. Risk assessments and climate-match models indicate that the Great Lakes are vulnerable to tench invasion, and they signal the need for timely comprehensive actions, including development and implementation of monitoring and rapid-response protocols, including prevention or slowing of natural dispersal through canals.

The structure and composition of epilithic diatom communities of the St. Lawrence and Ottawa rivers in the Montreal area

1981 ◽  
Vol 59 (3) ◽  
pp. 377-387 ◽  
Author(s):  
Michèle A. de Seve ◽  
Melvin E. Goldstein
Keyword(s):  
Species Richness ◽  
Information Measure ◽  
The South ◽  
Ottawa River ◽  
Diatom Communities ◽  
Upstream Station ◽  
South Shore ◽  
Lower Biomass ◽  
Epilithic Diatom ◽  
St Lawrence River

The structure and composition of epilithic diatom communities were studied at five stations in the St. Lawrence River and one station in the Ottawa River, adjacent to the south shore of the island of Montreal. The diatom flora was composed of 139 species and varieties of Bacillariophyceae. The species composition generally reflected a eutrophic and organically polluted environment. The structure of the diatom communities of the Ottawa River (station I) and of the St. Lawrence River upstream (station II) and downstream along the south shore of the island of Montreal (stations III and IV) was similar with respect to total number of species (41–44 species), diversity (species richness (d): 3.01–3.88 and Shannon-Weiner information measure of diversity [Formula: see text]: 2.01–3.34), and biomass (463.9–1656.0 μm3/mm2). Further downstream station V had fewer species (12 species) and a significantly (P < 0.05) lower diversity (species richness d: 1.87 and Shannon-Weiner information measure of diversity [Formula: see text]: 0.35). The station below it (station VI) had a significantly (P < 0.05) lower biomass (51.2 μm3/mm2) and a lower density (68 cells/mm2). The structure and composition of the diatom communities at the different stations are discussed in relation to environmental factors.

Zebra Mussels as Biomonitors for Organic Contaminants in the Lower Great Lakes

1996 ◽  
Vol 31 (2) ◽  
pp. 411-432 ◽  
Author(s):  
Michael E. Comba ◽  
Janice L. Metcalfe-Smith ◽  
Klaus L.E. Kaiser
Keyword(s):  
Great Lakes ◽  
Organic Contaminants ◽  
Lake Erie ◽  
Soft Tissues ◽  
Lake Ontario ◽  
Dry Weight ◽  
Zebra Mussels ◽  
Organic Contamination ◽  
Contamination Levels ◽  
St Lawrence River

Abstract Zebra mussels were collected from 24 sites in Lake Erie, Lake Ontario and the St. Lawrence River between 1990 and 1992. Composite samples of whole mussels (15 sites) or soft tissues (9 sites) were analyzed for residues of organochlo-rine pesticides and PCBs to evaluate zebra mussels as biomonitors for organic contaminants. Mussels from most sites contained measurable quantities of most of the analytes. Mean concentrations were (in ng/g, whole mussel dry weight basis) 154 ΣPCB, 8.4 ΣDDT, 3.5 Σchlordane, 3.4 Σaldrin, 1.4 ΣBHC, 1.0 Σendosulfan, 0.80 mirex and 0.40 Σchlorobenzene. Concentrations varied greatly between sites, i.e., from 22 to 497 ng/g for ΣPCB and from 0.08 to 11.6 ng/g for ΣBHC, an indication that mussels are sensitive to different levels of contamination. Levels of ΣPCB and Σendosulfan were highest in mussels from the St. Lawrence River, whereas mirex was highest in those from Lake Ontario. Overall, mussels from Lake Erie were the least contaminated. These observations agree well with the spatial contaminant trends shown by other biomoni-toring programs. PCB congener class profiles in zebra mussels are also typical for nearby industrial sources, e.g., mussels below an aluminum casting plant contained 55% di-, tri- and tetrachlorobiphenyls versus 31% in those upstream. We propose the use of zebra mussels as biomonitors of organic contamination in the Great Lakes.

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.

Managing the Impacts of Human Activities on Fish Habitat: The Governance, Practices, and Science

2015 ◽  
Keyword(s):  
Mississippi River ◽  
Fish Habitat ◽  
Organizational Structures ◽  
Mature Female ◽  
Cumulative Effects ◽  
Past Century ◽  
Sargasso Sea ◽  
Ottawa River ◽  
Governance Practices ◽  
St Lawrence River

<em>Abstract.</em>—American Eel mortality has increased substantially over the past century due largely to significant cumulative effects of fishing and fish passage through hydro-electric turbines across their range. Nowhere has this been more pronounced than in waters of the St. Lawrence River, Lake Ontario, Ottawa River and associated watersheds. We illustrate this by examining the cumulative effects of hydro-electric facilities on eels migrating downstream through the Mississippi River and Ottawa River, and outline further impacts eels encounter en route to spawn in the Sargasso Sea. The probability of a mature female eel surviving its emigration through the Mississippi and Ottawa River to the upper St. Lawrence River is estimated to be as low as 2.8% due to turbine mortalities alone (2.8–40%). Mortality risk increases as the eel attempts to run the gauntlet of fisheries in the lower St. Lawrence River and the probability of out-migration survival is estimated to be as low as 1.4%. Some mortalities could be mitigated through improved application of existing laws, development of policy requiring consideration of cumulative effects and improved integration among program areas responsible for sustainable management of fisheries, biodiversity, dams and hydro-electric facilities. We recommend changes to policy, procedures and internal organizational structures provided with clear directions, and call for increased accommodation of Aboriginal perspectives.

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