Salinity tolerances and preferences of fry of two species of sympatric sticklebacks: possible mechanisms of habitat segregation

1984 ◽  
Vol 62 (6) ◽  
pp. 1048-1051 ◽  
Author(s):  
Suzanne Campeau ◽  
Helga Guderley ◽  
Gerard Fitzgerald
Keyword(s):  
Salt Marshes ◽  
Gasterosteus Aculeatus ◽  
Reproductive Activity ◽  
Tidal River ◽  
Differential Distribution ◽  
Lawrence Estuary ◽  
Parental Stock ◽  
Salinity Preference ◽  
Tolerance Field ◽  
St Lawrence Estuary

During their period of reproductive activity, the sticklebacks Gasterosteus aculeatus (trachurus) and Gasterosteus wheatlandi show differences in their use of available microhabitats in the salt marshes of the St. Lawrence estuary. Gasterosteus aculeatus is found at all stations along a tidal river, Rivière des Vases, while G. wheatlandi is absent from the sites exposed to freshwater. To determine whether the juveniles of these species have different sensitivities to low salinities which could account for their differential distribution, we examined the salinity tolerances of laboratory-reared fry. Adult G. aculeatus (form trachurus) and G. wheatlandi collected at the mouth of the Rivière des Vases were used as the parental stock. For 1-week-old fry of both species, freshwater represented a marginal environment. Following exposure to freshwater for 96 h, G. aculeatus fry showed a 22% mortality while G. wheatlandi showed a significant decrease in growth. By 5 weeks of age, both species were euryhaline. Despite a wide salinity tolerance, field-collected G. wheatlandi significantly preferred a salinity of 7–14‰ while field-collected G. aculeatus fry showed no significant salinity preference.

The effects of bird predation on an estuarine stickleback (Pisces: Gasterosteidae) community

1985 ◽  
Vol 63 (2) ◽  
pp. 301-307 ◽  
Author(s):  
F. G. Whoriskey ◽  
G. J. Fitzgerald
Keyword(s):  
Fish Community ◽  
Gasterosteus Aculeatus ◽  
Selective Predation ◽  
Bird Predation ◽  
Lawrence Estuary ◽  
Nycticorax Nycticorax ◽  
Larus Delawarensis ◽  
Night Heron ◽  
Marsh Pools ◽  
St Lawrence Estuary

Eight species of birds fed on a community of sticklebacks living in salt marsh pools along the southern shore of the St. Lawrence estuary in May and June when the fish breed. Three birds, the black-crowned night heron (Nycticorax nycticorax), the bronzed grackle (Quiscalus quiscula), and the ring-billed gull (Larus delawarensis) accounted for 80% of the estimated captures. Bird predation removed about 30% of the sticklebacks in the marsh. Significantly more male than female Gasterosteus aculeatus and G. wheatlandi were eaten, indicating selective predation is playing a role in structuring this fish community.

Habitat segregation among the age groups of Gasterosteus aculeatus (Pisces: Gasterosteidae) in the middle St. Lawrence estuary, Canada

1990 ◽  
Vol 68 (6) ◽  
pp. 1202-1208 ◽  
Author(s):  
Paul Picard Jr. ◽  
Julian J. Dodson ◽  
Gérard J. FitzGerald
Keyword(s):  
Breeding Season ◽  
Gasterosteus Aculeatus ◽  
Age Groups ◽  
Minimum Size ◽  
Spawning Period ◽  
Lawrence Estuary ◽  
Age Related ◽  
Tidal Rivers ◽  
Marsh Pools ◽  
St Lawrence Estuary

Previous studies of migratory populations of sticklebacks (Pisces: Gasterosteidae) have been exclusively limited to their biology on the spawning grounds during the spring breeding season. In 1985 and 1986, we studied the ecology of the threespine stickleback (Gasterosteus aculeatus) in three subhabitats of the middle St. Lawrence estuary before, during, and after the breeding season: (i) the open waters of the estuary, (ii) a series of intertidal salt marsh pools, and (iii) two tidal rivers (Rivière des Vases and Rivière Trois-Pistoles). In spring, our catch data in the various subhabitats showed that adults moved from the open waters of the estuary towards the tidal rivers and tide pools. Catches of adults in all subhabitats subsequently declined, whereas the young of the year (age 0+) became increasingly abundant. In this area, G. aculeatus live for 2 years and are physiologically capable of breeding during their first summer as adults. However, we found age-related differences in habitat use between the two adult year classes. Age 1+ fish were never more abundant than age 2+ fish in Rivière des Vases, in the tide pools, and in the open waters of the estuary, whereas age 1+ fish were more abundant than age 2+ fish in Rivière Trois-Pistoles. Throughout the breeding season, gonadosomatic indices of female G. aculeatus were the same for the two age groups. Total lengths of age 0+ fish captured in the various subhabitats suggest that the major spawning period is limited to May and June. Age 0+ fish do not leave the tide pools for the open waters of the estuary before having attained a certain minimum size.

The effects of drought and waterlogging conditions on the performance of an endemic annual plant, Aster laurentianus

2000 ◽  
Vol 78 (1) ◽  
pp. 40-46 ◽  
Author(s):  
Gilles Houle ◽  
Annie Belleau
Keyword(s):  
Salt Marshes ◽  
Carbon Assimilation ◽  
Late Summer ◽  
Annual Plant ◽  
Endemic Plant ◽  
Lawrence Estuary ◽  
Negative Effect ◽  
Effects Of Drought ◽  
Interannual Fluctuations ◽  
St Lawrence Estuary

Aster laurentianus Fernald is an annual plant endemic to the St. Lawrence estuary. It typically grows in salt marshes at the periphery of shallow lagoons. In this habitat, the water level fluctuates greatly both within and between years. Such fluctuations may induce significant interannual variations in marsh-plant populations. In this study, we experimentally determined the effects of different water availability conditions, imposed at various stages of plant development, on the performance of A. laurentianus. Waterlogging had no significant effect on net carbon assimilation rate, plant growth, and biomass allocation. However, a drought stress at the time of reproductive-bud differentiation had a negative effect on flower-head production. We propose that occasional reproductive failures resulting from late-summer droughts may cause significant interannual fluctuations in the size of A. laurentianus populations, potentially making them more susceptible to local extinction.Key words: Aster laurentianus, endemic plant, Îles-de-la-Madeleine, rare plant, salt marshes, water stress.

Evidence for differential predation on an estuarine stickleback community

1981 ◽  
Vol 59 (12) ◽  
pp. 2394-2395 ◽  
Author(s):  
Gérard J. FitzGerald ◽  
Jean-Denis Dutil
Keyword(s):  
Gasterosteus Aculeatus ◽  
Pungitius Pungitius ◽  
Lawrence Estuary ◽  
Nycticorax Nycticorax ◽  
Nest Sites ◽  
Differential Predation ◽  
Apeltes Quadracus ◽  
Breeding Grounds ◽  
Night Heron ◽  
St Lawrence Estuary

The diet of the black-crowned night heron (Nycticorax nycticorax) feeding in June and July along the southern shore of the St. Lawrence Estuary was composed primarily of the threespine stickleback Gasterosteus aculeatus. Three other sticklebacks, G. wheatlandi, Pungitius pungitius, and Apeltes quadracus occur in areas where the birds feed but were not eaten. It is suggested that differential predation on G. aculeatus may diminish interspecific competition for nest sites where the four stickleback species co-occur on the breeding grounds.

Soil carbon may be maintained under grazing in a St Lawrence Estuary tidal marsh

2009 ◽  
Vol 36 (4) ◽  
pp. 312-320 ◽  
Author(s):  
O.T. YU ◽  
G.L. CHMURA
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Salt Marshes ◽  
Carbon Sink ◽  
Economic Incentive ◽  
Plant Litter ◽  
Root Production ◽  
Belowground Production ◽  
Lawrence Estuary ◽  
St Lawrence Estuary

SUMMARYProduction of belowground organic matter is critical to sustainability of salt marshes. It plays a role in vertical soil accretion, a process essential for salt marshes to maintain their relative elevation and persist as sea levels rise. This paper examines belowground production and soil carbon of a high-latitude saltmarsh in the St Lawrence Estuary (Québec, Canada), which had been subjected to six years of sheep grazing. In the seventh year, without sheep, organic matter production in grazed and ungrazed sections was assessed by examining harvests of plant litter, end-of-season standing crop, and the roots and rhizomes present in in-growth cores. Excepting salinity, porewater chemistry varied little. The grazed marsh had higher soil carbon density and belowground production, yet lower aboveground biomass. Grazing reduces plant litter and increases solar exposure, soil temperature (at this latitude, soil remained frozen until April) and evapotranspiration, thus raising soil salinity and nitrogen demand, the latter a driver of root production. Grazing may not be detrimental to soil carbon storage. Permitting certain types of grazing on restored salt marshes previously drained for agriculture would provide economic incentive to restore tidal flooding, because the natural carbon sink provided in the recovered marsh would make these lands eligible for carbon payments.

Seasonal nutrient fluxes variability of northern salt marshes: examples from the lower St. Lawrence Estuary

2009 ◽  
Vol 17 (6) ◽  
pp. 655-673 ◽  
Author(s):  
Patrick Poulin ◽  
Émilien Pelletier ◽  
Vladimir G. Koutitonski ◽  
Urs Neumeier
Keyword(s):  
Salt Marshes ◽  
Nutrient Fluxes ◽  
Lawrence Estuary ◽  
St Lawrence Estuary

Benthic diatom communities from two salt marshes of the St. Lawrence Estuary (Canada)

2010 ◽  
Vol 23 (4) ◽  
pp. 349-358 ◽  
Author(s):  
Michèle A. De Sève ◽  
Patrick Poulin ◽  
Émilien Pelletier ◽  
Karine Lemarchand
Keyword(s):  
Salt Marshes ◽  
Extracellular Polymeric Substances ◽  
The Other ◽  
High Marsh ◽  
Biological Index ◽  
Sediment Grain Size ◽  
Lawrence Estuary ◽  
Marsh Area ◽  
Diatom Communities ◽  
St Lawrence Estuary

Microphytobenthic diatom communities were investigated in the high and low sections of two salt marshes of the Lower St. Lawrence Estuary (eastern Canada): one featuring a sandy low marsh zone (Pointe-aux-Épinettes; PE) and one with a muddy low marsh area (Pointe-au-Père; PP). Based on diatom composition and diversity, bacterial abundance, chlorophyll-a, phaeopigments and geochemical analyses (Corg, Ntot, granulometry, extracellular polymeric substances), the PP high marsh area appeared to be singular compared to the other sampling sites. Estimated surface biomass ranged from 11 to 71 g C•m-2in the PE marsh and from 24 to 486 g C•m-2in the PP marsh. A higher diversity of diatom species was observed in the PP high marsh area with a dominance of epipelic forms, in opposition to the dominant epipsammic forms at the other sites. Statistical analyses showed that diatom density was mainly affected by nutrient availability while the relative abundance of epipelic and epipsammic species was related to sediment grain size. This study provides original data on the composition of benthic diatoms in surface sediments in St. Lawrence saltmarshes during summer time that represent the first step to the determination of the DBI (Diatom biological index) of these northern environments.

Temperature preferences of three sympatric sticklebacks (Gasterosteidae)

1987 ◽  
Vol 65 (6) ◽  
pp. 1573-1576 ◽  
Author(s):  
Stephanie Lachance ◽  
Pierre Magnan ◽  
Gerard J. FitzGerald
Keyword(s):  
Gasterosteus Aculeatus ◽  
Sympatric Species ◽  
Habitat Partitioning ◽  
Pungitius Pungitius ◽  
Temperature Preference ◽  
Lawrence Estuary ◽  
Preferred Temperatures ◽  
Temperature Preferences ◽  
St Lawrence Estuary ◽  
Reproductive Migration

We determined the temperature preferences of three sympatric species of sticklebacks in the laboratory to see if differences in preferences could explain variation in times of reproductive migration to and from salt marsh tide pools along the southern shore of the St. Lawrence estuary, Quebec. The preferred temperatures were 9–12 °C for Gasterosteus aculeatus (form trachurus) and 11–14 °C for G. wheatlandi, while Pungitius pungitius showed a bimodal preference of 9–10 °C and 15–16 °C. In the field, G. aculeatus and G. wheatlandi left the tide pools earlier in the season than P. pungitius. Our results suggest that temperature preference may play a role in habitat partitioning among these species, hence facilitating their coexistence at high densities in the pools.

scholarly journals Benthic fluxes of dissolved organic nitrogen in the lower St. Lawrence estuary and implications for selective organic matter degradation

2013 ◽  
Vol 10 (11) ◽  
pp. 7609-7622 ◽  
Author(s):  
M. Alkhatib ◽  
P. A. del Giorgio ◽  
Y. Gelinas ◽  
M. F. Lehmann
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Bottom Water ◽  
Estuarine Sediments ◽  
Internal Source ◽  
Lawrence Estuary ◽  
Element Partitioning ◽  
Sediment Porewaters ◽  
St Lawrence Estuary

Abstract. The distribution of dissolved organic nitrogen (DON) and carbon (DOC) in sediment porewaters was determined at nine locations along the St. Lawrence estuary and in the gulf of St. Lawrence. In a previous manuscript (Alkhatib et al., 2012a), we have shown that this study area is characterized by gradients in the sedimentary particulate organic matter (POM) reactivity, bottom water oxygen concentrations, and benthic respiration rates. Based on the porewater profiles, we estimated the benthic diffusive fluxes of DON and DOC in the same area. Our results show that DON fluxed out of the sediments at significant rates (110 to 430 μmol m−2 d−1). DON fluxes were positively correlated with sedimentary POM reactivity and varied inversely with sediment oxygen exposure time (OET), suggesting direct links between POM quality, aerobic remineralization and the release of DON to the water column. DON fluxes were on the order of 30 to 64% of the total benthic inorganic fixed N loss due to denitrification, and often exceeded the diffusive nitrate fluxes into the sediments. Hence they represented a large fraction of the total benthic N exchange, a result that is particularly important in light of the fact that DON fluxes are usually not accounted for in estuarine and coastal zone nutrient budgets. In contrast to DON, DOC fluxes out of the sediments did not show any significant spatial variation along the Laurentian Channel (LC) between the estuary and the gulf (2100 ± 100 μmol m−2 d−1). The molar C / N ratio of dissolved organic matter (DOM) in porewater and the overlying bottom water varied significantly along the transect, with lowest C / N in the lower estuary (5–6) and highest C / N (> 10) in the gulf. Large differences between the C / N ratios of porewater DOM and POM are mainly attributed to a combination of selective POM hydrolysis and elemental fractionation during subsequent DOM mineralization, but selective adsorption of DOM to mineral phases could not be excluded as a potential C / N fractionating process. The extent of this C- versus N- element partitioning seems to be linked to POM reactivity and redox conditions in the sediment porewaters. Our results thus highlight the variable effects selective organic matter (OM) preservation can have on bulk sedimentary C / N ratios, decoupling the primary source C / N signatures from those in sedimentary paleoenvironmental archives. Our study further underscores that the role of estuarine sediments as efficient sinks of bioavailable nitrogen is strongly influenced by the release of DON during early diagenetic reactions, and that DON fluxes from continental margin sediments represent an important internal source of N to the ocean.

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