Étude des Trématodes parasites de <i>Littorina saxatilis</i> (Olivi) et de leurs effets sur cet hôte

Combescot-Lang, Catherine

doi:10.1051/parasite/1976511027

Cited by 9 publications

(9 citation statements)

References 2 publications

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“…This is probably the main reason why digenean species with complex life cycles (3 hosts) predominate in the species composition and prevalence in periwinkles on the shores of Germany, France, Britain and Northern Ireland (e.g. James 1969, Werding 1969, Combescot-Lang 1976, Lauckner 1980, 1984b, Hughes & Answer 1982, Irwin 1983, Matthews et al 1985, Newel1 1986. The cause of this difference is not known, but it is possible that the dispersion of free-swimming cercariae and the metacercariae through the movements of the second intermediate host is more efficient in milder environments.…”

Section: Discussionmentioning

confidence: 99%

Distribution patterns of marine bird digenean larvae in periwinkles along the southern coast of the Barents Sea

Галактионов

Bustnes²

1999

Dis. Aquat. Org.

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An important component of the parasite fauna of seabirds in arctic regions are the flukes (Digena). Different species of digeneans have life cycles w h c h may consist of 1 intermediate host and no free-living larval stages, 2 intermediate hosts and 1 free-living stage, or 2 intermediate hosts and 2 free-living larval stages. This study examined the distribution of such parasites in the intertidal zones of the southern coast of the Barents Sea (northwestern Russia and northern Norway) by investigating 2 species of periwinkles (Littorina saxatilis and L. obtusata) which are intermediate hosts of many species of digeneans. A total of 26020 snails from 134 sampling stations were collected. The study area was divided into 5 regions, and the number of species, frequency of occurrence and prevalence of different digenean species and groups of species (depending on life cycle complexity) were compared among these regions, statistically controlling for environmental exposure. We found 14 species of digeneans, of which 13 have marine birds as final hosts. The number of species per sampling station increased westwards, and was hlgher on the Norwegian coast than on the Russian coast. The frequency of occurrence of digeneans with more than 1 intermediate host increased westwards, making up a larger proportion of the digeneans among infected snails. This was significant in L. saxatilis. The prevalence of different species showed the same pattern, and significantly more snails of both species were infected with bgeneans with complicated Life cycles in the western regions. In L. saxatilis, environmental exposure had a statistically significant effect on the distribution of the most common digenean species This was less obvious in L. obtusata. The causes of changing species composition between regions are probably (1) the harsh climate in the eastern part of the study area reducing the probability of successful transmission of digeneans with complicated life cycles, and (2) the distribution of different final hosts.

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Section: Discussionmentioning

confidence: 99%

Distribution patterns of marine bird digenean larvae in periwinkles along the southern coast of the Barents Sea

Галактионов

Bustnes²

1999

Dis. Aquat. Org.

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“…1937, Bourns 1963, Vernberg eta!. 1969, Werding 1969, Combescot-Lang 1976, Vaes 1979, Rohde 1981, Kuris 1990, Fernandez and Esch 1991, the expected number of double infections of trematode species i andj is EiJ: EiJ = Npp 1 , where N is the number of hosts (infected and uninfected) and Pi and p 1 represent the prevalences (where prevalence is the proportion ofhosts infected, Margolis et a!. 1982) of species i and j. Summing EiJ over all species pairs gives the expected number of double infections in a sample (~EiJ).…”

Section: Determining Structure With a Null Modelmentioning

confidence: 99%

“…Although trematode species might isolate themselves if they specialized among various host phenotypes, or more readily infected unparasitized than parasitized snails, there is no evidence that this occurs in our host-parasite system with the possible exception of size selectivity (Sousa 1990(Sousa , 1993. In experimental studies of other snail-trematode systems, if miracidia (searching stages hatched from trematode eggs) were selective, they were more likely to penetrate snails infected with other trematode species than uninfected snails , Kuris 1973, Lie et al 1973, 1976,Boss 1977,Jourdane 1980,Lie 1982. The propensity of trematode miracidia to penetrate infected hosts would increase the incidence of parasite co-occurrences and make our analysis of structure conservative.…”

Section: Interpretation Of Structurementioning

confidence: 99%

Analysis of Larval Trematode Communities

Lafferty¹,

Sammond²,

Kuris³

1994

Ecology

117

130

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We can compare natural communities with null models of communities to indicate how they differ from random assemblages of species (i.e., how much structure is present). However, because null models draw on observed values of species' prevalences, whatever structure already exists in natural communities affects the composition of a null model and weakens its comparative power. To address this, we developed formulae to estimate "pre—interactive" species prevalences permitting a more sensitive quantification of community structure. Nonetheless, if a null model deviates from the community that we base it on, it is difficult to separate the effects of heterogeneity in recruitment from competition. We have developed a method to test for each independently. Applying our analytical techniques to a well—studied guild of larval trematodes in the salt marsh snail Cerithidea californica revealed that competitive interactions among species were the most significant structuring force. Interestingly, spatial heterogeneity acted to significantly intensify species co—occurrences. This differs from previous studies, which argued that the isolating effects of spatial heterogeneity, not competition, structure these communities by reducing co—occurrences.

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“…Ewers, 1960;Werding, 1969;Robson and Williams, 1970;Vaes, 1979;Vernberg et aI., 1969;DeCoursey and Vernberg, 1974;Combescot-Lang, 1976;Rhode, 1981). Ewers, 1960;Werding, 1969;Robson and Williams, 1970;Vaes, 1979;Vernberg et aI., 1969;DeCoursey and Vernberg, 1974;Combescot-Lang, 1976;Rhode, 1981).…”

Section: Infracommunity Interactionsmentioning

confidence: 99%

Parasite Communities: Patterns and Processes

1989

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Étude des Trématodes parasites de Littorina saxatilis (Olivi) et de leurs effets sur cet hôte

Cited by 9 publications

References 2 publications

Distribution patterns of marine bird digenean larvae in periwinkles along the southern coast of the Barents Sea

Distribution patterns of marine bird digenean larvae in periwinkles along the southern coast of the Barents Sea

Analysis of Larval Trematode Communities

Parasite Communities: Patterns and Processes

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