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.

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.

Climate change and abundance cycles of two sympatric populations of smelt (Osmerus mordax) in the middle estuary of the St. Lawrence River, Canada

2001 ◽  
Vol 58 (10) ◽  
pp. 2048-2058 ◽  
Author(s):  
M Mingelbier ◽  
F Lecomte ◽  
J J Dodson
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Climatic Factors ◽  
Future Climate Change ◽  
Osmerus Mordax ◽  
Sympatric Populations ◽  
North Shore ◽  
South Shore ◽  
Middle Estuary ◽  
St Lawrence River

Commercial catches of two ecologically distinct sympatric smelt (Osmerus mordax) populations segregated along the two shores of the St. Lawrence middle estuary exhibited inverse patterns with periodicities on the order of 30 years. The influence of water level in the St. Lawrence River and air temperature, chosen to reflect variations in hydrology and climate, differed markedly between the two populations. Analyses revealed that both water level and temperature were generally positively related with north-shore smelt landings and negatively related with south-shore smelt landings. For both populations, a number of significant climatic factors contributing to variance in smelt landings were lagged by one to three years relative to the year of landings, indicating that climatic variables influenced smelt recruitment. The contrasting role of hydroclimatic variables in driving these abundance cycles is likely related to differential exploitation of estuarine habitats; the south-shore population is associated with shallow shoal habitat, whereas the north-shore population is associated with deep channel habitat. The responses of the two smelt populations also reflect the fundamental ecological differences existing between shoal and channel habitats, indicating that future climate change may differentially affect other populations or species that are segregated between these two habitats.

Hudson River Fishes and their Environment

2006 ◽  
Keyword(s):  
New York ◽  
Species Richness ◽  
River Estuary ◽  
Hudson River ◽  
Anthropogenic Sources ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Additional Species ◽  
Acipenser Brevirostrum ◽  
River Drainage

<em>Abstract.</em>—The Hudson River Estuary (defined here as the Hudson River drainage and New York Harbor) is home to a large and diverse ichthyofauna. Estimates of species richness reflect both their geographic boundaries and time periods. The most complete estimate is for the Hudson River drainage north of the southern tip of Manhattan, where, as of 2005, 212 fish species have been recorded. This includes 11 new forms not reported in the most recently published tally (1990). We categorize the fishes of the Hudson River drainage as derived from 12 zoogeographic or anthropogenic sources (including species for which we make no judgment [<em>n </em>= 26]), the largest contributions from which include temperate marine strays (<em>n </em>= 65), introduced species (<em>n </em>= 28), and freshwater species that survived Pleistocene glaciations in Atlantic coastal refugia (<em>n </em>= 21). Additional species appear to have invaded from the Mississippi refugia, some naturally (<em>n </em>= 11) and some later, via canals (<em>n </em>= 11). Only ten diadromous fishes occur in the estuary, but many of these are, or have been, commercially and recreationally important (e.g., Atlantic sturgeon <em>Acipenser oxyrinchus</em>, American shad <em>Alosa sapidissima</em>, and striped bass <em>Morone saxatilis</em>). Extremely high seasonal temperature changes in the main-channel Hudson River foster a seasonally dynamic ichthyofauna with relatively few species occurring year round. However, the small number of resident estuarine fishes (<em>n </em>= 8) often occur in high abundances. Species richness peaks between June and September and reaches a minimum in winter. Long-term data indicate that although species richness has increased with the additions of new species, diversity is decreasing because of the decrease in population size of certain species, especially native cyprinids. The Hudson estuary hosts a population of one federally endangered species, shortnose sturgeon <em>Acipenser brevirostrum</em>, which is flourishing. Only one species, the anadromous rainbow smelt <em>Osmerus mordax </em>appears to have become extirpated in the Hudson Estuary.

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.

Larval transport, vertical distribution, and localized recruitment in anadromous rainbow smelt (Osmerus mordax)

2006 ◽  
Vol 63 (12) ◽  
pp. 2822-2836 ◽  
Author(s):  
I R Bradbury ◽  
K Gardiner ◽  
P VR Snelgrove ◽  
S E Campana ◽  
P Bentzen ◽  
...  
Keyword(s):  
Larval Dispersal ◽  
River Estuary ◽  
Larval Transport ◽  
Vertical Position ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Negative Geotaxis ◽  
Larvae And Juveniles ◽  
Limited Dispersal ◽  
Order Of Magnitude

We examined larval dispersal and behaviour in rainbow smelt (Osmerus mordax) from the Salmonier River estuary, Newfoundland, during 2003–2005. Riverine ichthyoplankton surveys indicate that larval transport into the estuary is restricted to a two-week period in late June. A passive drifter experiment and the spatial distribution of larvae and juveniles suggest limited dispersal and low export from the estuary. The estuary exhibited low inflow and stratification in summer and high inflow with a stable freshwater layer in fall. Summer and fall winds are primarily onshore. We hypothesised that larval vertical swimming behaviour limits dispersal and export. Larval vertical position and swimming ability were examined through lab-based experiments conducted 0–10 and 90 days after hatching. Measurements of swim speed indicate an order of magnitude (p < 0.001) improvement in swimming capacity between larvae and juveniles. One-week after hatching, larvae displayed consistent negative geotaxis, whereas juveniles were generally deeper and displayed negative geotaxis in light and positive geotaxis in the dark. The contrasting light-mediated geotactic behavior between development stages corresponds to ontogenetic shifts in swimming abilities and seasonal changes in estuarine circulation. We suggest that the interaction between behaviour, ontogeny, and hydrography results in limited transport and a tendency for estuarine-scale recruitment, despite an extensive pelagic period.

Dietary overlap and food resource partitioning among fish species of a tropical estuary in Northeastern Brazil

Gaia Scientia ◽  
2016 ◽  
Vol 10 (4) ◽  
pp. 86-95 ◽  
Author(s):  
Adna Ferreira da Silva Garcia ◽  
Ana Lúcia Vendel
Keyword(s):  
Resource Partitioning ◽  
Species Coexistence ◽  
Food Resource ◽  
River Estuary ◽  
Niche Overlap ◽  
Northeastern Brazil ◽  
Dietary Overlap ◽  
Feeding Niche ◽  
Tropical Environments ◽  
Food Resource Partitioning

The current work investigates dietary overlap and food partitioning among nine abundant carnivorous fishes caught in the shallow waters of the Paraíba do Norte river estuary, Paraíba State, Brazil. Fishes were sampled with a beach seine net between January and December 2008 and a total of 958 specimens had their stomach content analyzed. Crustacea was the dominant food resource for Lutjanus alexandrei, L. jocu and Bathygobius soporator, whereas Telostei were consumed mainly by Centropomus undecimalis and C. parallelus. In contrast, Polychaeta were preyed upon mainly by Diapterus rhombeus, Eucinostomus argenteus, Sciades herzbergii and S. parkeri. Although most species consumed similar food items, they did that in varying proportions and amounts. Overall, the niche overlap among species was low (< 0.60), but there were several cases where pair of species had their feeding niche highly overlapped (between 0.72 and 0.97). These findings corroborate the hypothesis that food resource partitioning determines species coexistence in estuarine tropical environments.

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.

Planktivory by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) on microcrustacean zooplankton and dreissenid (Bivalvia: Dreissenidae) veligers in southern Lake Ontario

1995 ◽  
Vol 52 (5) ◽  
pp. 925-935 ◽  
Author(s):  
Edward L. Mills ◽  
Connie Adams ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Edward F. Roseman
Keyword(s):  
Laboratory Experiments ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Field Observations ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Consumption Rates ◽  
South Shore ◽  
Young Of The Year ◽  
Veliger Larvae

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.

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