Evidence for differential predation on an estuarine stickleback community

1981 ◽  
Vol 59 (12) ◽  
pp. 2394-2395 ◽  
Author(s):  
Gérard J. FitzGerald ◽  
Jean-Denis Dutil

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.

1985 ◽  
Vol 63 (2) ◽  
pp. 301-307 ◽  
Author(s):  
F. G. Whoriskey ◽  
G. J. Fitzgerald

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.


1980 ◽  
Vol 58 (7) ◽  
pp. 1259-1263 ◽  
Author(s):  
Jacqueline Tremblay ◽  
Laurence N. Ellison

Reproductive success of black-crowned night herons (Nycticorax nycticorax) was studied on two islands during 2 years in the St. Lawrence Estuary. The mean size of complete clutches was 4.1 eggs. The mean number of young fledged per active nest varied from 0.5 to 2.1 young according to year and to island. The mean number of young fledged per successful nest varied from 2.1 to 3.0. Toxic chemical residues in eggs were relatively low, and we found no evidence of eggshell thinning. We conclude that reproduction was normal and probably sufficient to maintain a stable population.


1987 ◽  
Vol 65 (6) ◽  
pp. 1573-1576 ◽  
Author(s):  
Stephanie Lachance ◽  
Pierre Magnan ◽  
Gerard J. FitzGerald

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.


1974 ◽  
Vol 31 (6) ◽  
pp. 1135-1139 ◽  
Author(s):  
George Hanek ◽  
Kalman Molnar

In 224 fish of nine species from Matamek River system 38 genera of parasites were recovered (12 Protozoa, 3 Monogenea, 6 Digenea, 6 Cestoda, 6 Nematoda, 2 Acanthocephala, 3 Copepoda). Six genera of parasites were noted in Salmo salar, Salvelinus fontinalis harbored 17 genera, S. alpinus 5 genera, Osmerus mordax 4 genera, Anguilla rostrata 9 genera, Catostomus catostomus 8 genera, Apeltes quadracus 1 genus, Gasterosteus aculeatus 12 genera, and Pungitius pungitius 9 genera.


1984 ◽  
Vol 62 (6) ◽  
pp. 1048-1051 ◽  
Author(s):  
Suzanne Campeau ◽  
Helga Guderley ◽  
Gerard Fitzgerald

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.


2005 ◽  
Vol 37 (1-6) ◽  
pp. 109-117 ◽  
Author(s):  
Walter J. Marcisz ◽  
Jeffrey M. Levengood ◽  
Allison M. Klement ◽  
Margaret A. Kurcz

The number of active black-crowned night-heron (Nycticorax nycticorax) nesting colonies in Illinois has declined significantly over the past century. Habitat loss/degradation and other factors such as exposure to environmental contaminants and competition for nest sites at established colonies may have contributed to this decline. In this study, we examined recent trends in population levels of Black-crowned Night-Herons nesting at wetlands associated with Lake Calumet in southeastern Chicago, Illinois. The number of black-crowned night herons nesting annually at these wetlands has fluctuated widely over the last two decades. Immigration of herons from riverine colonies may have driven population increases during the mid-1980s and early 1990s. However, this population has remained relatively stable at between 300 and 400 pairs during 1997–2003.


1990 ◽  
Vol 68 (6) ◽  
pp. 1202-1208 ◽  
Author(s):  
Paul Picard Jr. ◽  
Julian J. Dodson ◽  
Gérard J. FitzGerald

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.


1975 ◽  
Vol 53 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Michael Wiles

Morphological and morphometric comparisons among adult and glochidial unionids from two Nova Scotian locations showed that Anodonta implicata, A. cataracta cataracta, A. c. fragilis, Elliptio complanatus, and Lampsilis radiata radiata were present. Gravidity studies suggested that fully developed glochidia occur from September to May in Anodonta marsupia, for only 5–6 weeks in June and July in E. complanatus, and perhaps at least from spring to early fall in L. r. radiata. Seven of 12 fish species sampled bore glochidia, which were identified in five host species by comparisons of their shapes and dimensions with those of glochidia from adult clams. Results were as follows: A. c. cataracta in Catostomus commersoni in June only, A. implicata or A. c. cataracta in Gasterosteus aculeatus in May and June, Anodonta sp. in Apeltes quadracus and Pungitius pungitius in June, and E. complanatus in Fundulus diaphanus in June and July. Thus, no relationships between gravidity periods of adult clams and infestation periods of their fish hosts by their glochidia were evident for species of Anodonta.


1985 ◽  
Vol 63 (4) ◽  
pp. 956-960 ◽  
Author(s):  
D. K. Cone ◽  
M. Wiles

The systematics and zoogeography of Gyrodactylus from gasterosteid fishes (Apeltes quadracus, Culaea inconstans, Pungitius pungitius, Gasterosteus aculeatus, and G. wheatlandi) in North America were examined through a study of museum-held specimens and fresh material collected from localities across Canada. Six species are considered specific to these fishes, namely: G. alexanderi Mizelle and Kritsky, 1967, G. avalonia Hanek and Threlfall, 1969 (syn. G. lairdi Hanek and Threlfall, 1969, G. memorialis Hanek and Threlfall, 1969, G. terranovae Hanek and Threlfall, 1969), G. canadensis Hanek and Threlfall, 1969, G. cameroni Hanek and Threlfall, 1970, G. eucaliae lkezaki and Hoffman, 1957, and an unidentified species resembling G. pungitii Malmberg, 1964. The fauna has striking morphological similarities to that parasitizing the same host fishes in Eurasia. In fact, G. avalonia, G. canadensis, and the unconfirmed species are considered sister species to G. arcuatus Bychowsky, 1933, G. branchicus Malmberg, 1964, and G. pungitii, respectively. The match-ups are considered to have evolved from three lineages that parasitized G. aculeatus and P. pungitius prior to Pleistocene dispersal that resulted in these fishes and their parasites extending over much of the northern hemisphere. Gyrodactylus cameroni from A. quadracus is probably of North American origin and a sister species of G. avalonia. Gyrodactylus alexanderi from Pacific coast G. aculeatus and G. eucaliae from C. inconstans in the continent's central region have ties with a Pacific lineage. The parasites' geographical distributions and possible evolutionary histories since Pleistocene glaciation are discussed.


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