Between-year variations in the development of crustacean zooplankton in the Norwegian subalpine lake, Øvre Heimdalsvatn

Larsson, Petter; Hansen, Heidi; Helland, Linda Kristin Bjørnstad

doi:10.1007/978-90-481-9388-2_6

Cited by 2 publications

(3 citation statements)

References 17 publications

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“…This finding is consistent with previous studies from Scandinavian boreal lakes where minnows had no impact on zooplankton when trout was also present in the lake (e.g. Larsson et al, 2010). Our research group is currently performing further studies on zooplankton abundance, which will allow testing fish effects on species density apart from presence/absence.…”

Section: Introduced Fish Invasiveness In Pyrenean Lakessupporting

confidence: 91%

Introduced fish in Pyrenean high mountain lakes: impact on amphibians and other organisms, and conservation implications

Miró¹,

Ventura²

2020

Limnetica

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Introduced fish in Pyrenean high mountain lakes: impact on amphibians and other organisms, and conservation implicationsPyrenean high mountain lakes are naturally fishless due to hydrographic barriers that have prevented the natural colonisation of fish species from lower elevation streams. However, there have been numerous introductions of trout and minnows to such ecosystems, either in historical and recent periods. Trout and minnow introductions can cause large ecological problems and ecosystem changes in high mountain lakes, since both taxa occupy the top of a lake's food web. The study had two objectives. First, we wanted to investigate which particular anthropogenic and environmental factors best explained fish presence in the Pyrenean lakes. For that purpose we collected data on trout and minnow occurrence from 520 high mountain lakes > 0.5 ha in the southern Pyrenees. The second objective was to investigate the effect of introduced fish on several groups of organisms such as amphibians, conspicuous macroinvertebrates, planktonic crustaceans and littoral epilithic community. For that purpose we sampled 1736 lakes and ponds at different levels of intensity. The distribution of Salmo trutta in the lakes of the southern slopes of the Pyrenees was best explained by both anthropogenic factors and lake characteristics, while only anthropogenic factors linked to recreational fishing were associated with the distribution of the exotic trout Salvelinus fontinalis and Oncorhynchus mykiss. In the case of minnow occurrence, previous presence of trout in the lake was the most explanative variable, confirming its association with its use as live-bait in recreational fishing. Fish presence was linked with the disappearance of most amphibian species. Despite fish had a high local effect, at Pyrenean range scale, western-eastern patterns of some environmental variables were the main drivers of amphibian species distribution. Minnows also showed a sizeable impact on the pelagic habitat, reducing the occurrence of some crustacean zooplankton species that appeared to be unaffected by trout. In addition, we confirmed the presence of a littoral trophic cascade that defines most of the characteristics of the littoral epilithon of Pyrenean high mountain lakes and ponds through fish predation of tadpoles and hence, by a drastic reduction of grazing activity.

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Section: Introduced Fish Invasiveness In Pyrenean Lakessupporting

confidence: 91%

Introduced fish in Pyrenean high mountain lakes: impact on amphibians and other organisms, and conservation implications

Miró¹,

Ventura²

2020

Limnetica

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“…The low abundance of copepods in the summer and autumn diet of S. trutta in Øvre Heimdalsvatn in 2013 does not support a substantial change in copepod consumption from 1969–1972 (Lien, ). Since Cyclops scutifer , a common first intermediate host of D. ditremum , is the only zooplankton species that overwinters in an active phase in Øvre Heimdalsvatn (Larsson et al, ), copepods recorded in the winter diet of S. trutta (Lien, ) must have been this species. Densities of C. scutifer in the lake have varied little from 1969 to 1999 (Larsson et al, ) and the increase in infection from around 1970 until the present is therefore most likely a result of an increased number of final hosts (mergansers and black‐throated loon) foraging in the lake, giving more droppings of Diphyllobothrium eggs.…”

Section: Discussionmentioning

confidence: 99%

“…Since Cyclops scutifer , a common first intermediate host of D. ditremum , is the only zooplankton species that overwinters in an active phase in Øvre Heimdalsvatn (Larsson et al, ), copepods recorded in the winter diet of S. trutta (Lien, ) must have been this species. Densities of C. scutifer in the lake have varied little from 1969 to 1999 (Larsson et al, ) and the increase in infection from around 1970 until the present is therefore most likely a result of an increased number of final hosts (mergansers and black‐throated loon) foraging in the lake, giving more droppings of Diphyllobothrium eggs. The outcome may be a higher proportion of infected copepods and thus more procercoids transferred to S. trutta even without any marked change in feeding upon copepods.…”

Section: Discussionmentioning

confidence: 99%

Plerocercoids of the cestode Diphyllobothrium ditremum in brown trout Salmo trutta: substantial increase in infection after establishment of European minnow Phoxinus phoxinus

Borgstrøm

Trømborg

Haugen

et al. 2017

Journal of Fish Biology

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This study focuses on plerocercoids of the cestode Diphyllobothrium ditremum in brown trout Salmo trutta from the subalpine lake Øvre Heimdalsvatn in south-central Norway. Salmo trutta was the only fish species in this lake until European minnow Phoxinus phoxinus was registered in 1969. The P. phoxinus population increased substantially in the following years. In contrast with the 1969-1972 period, when plerocercoids of D. ditremum were practically absent in S. trutta, there was a high prevalence and intensity of infection in the 2013 S. trutta samples. Because the life cycle of D. ditremum involves two larval stages, in copepods and salmonids and mature worms in piscivorous birds, such as mergansers and loons, a change in feeding ecology of S. trutta or changes in population densities of copepods, fish or birds might have influenced the infection pattern. No relationships between D. ditremum infection and muscle-tissue δ N signature or Hg concentration were found, indicating that infection is not a result of piscivory or cannibalism. Furthermore, consumption of copepods by S. trutta during summer and autumn was low. On the other hand, the number of piscivorous birds has increased, probably due to the presence of P. phoxinus as a new and numerous prey. An increased number of final D. ditremum hosts may have produced a higher output of cestode eggs, resulting in more infected copepods that in turn are consumed by S. trutta. Indirectly, P. phoxinus may therefore have caused the observed increased infection in S. trutta and thereby imposed further negative effects on S. trutta in high mountain areas.

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Between-year variations in the development of crustacean zooplankton in the Norwegian subalpine lake, Øvre Heimdalsvatn

Cited by 2 publications

References 17 publications

Introduced fish in Pyrenean high mountain lakes: impact on amphibians and other organisms, and conservation implications

Introduced fish in Pyrenean high mountain lakes: impact on amphibians and other organisms, and conservation implications

Plerocercoids of the cestode Diphyllobothrium ditremum in brown trout Salmo trutta: substantial increase in infection after establishment of European minnow Phoxinus phoxinus

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