Why biomanipulation can be effective in peaty lakes

Heerdt, Gerard ter; Hootsmans, M. J. M.

doi:10.1007/s10750-007-0594-9

Cited by 26 publications

(7 citation statements)

References 35 publications

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“…As a result, crayfish density will not be strongly coupled to the availability of macrophytes in lakes with organic sediments, such as our study lake. Therefore, grazing pressure on macrophytes is potentially high, particularly when predation on the crayfish is low, for instance when fish densities are low due to biomanipulation, as is the case in our study lake [40]. …”

Section: Discussionmentioning

confidence: 99%

“…In The Netherlands, P. clarkii was first observed in 1985 [30] and has rapidly spread throughout the peat district in the west of the country in the last decade(Figure 1). Many restoration projects have been executed to restore the water transparency and promote the return of macrophytes in the shallow water bodies of this peat district [4,39,40]. …”

Section: Introductionmentioning

confidence: 99%

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Invasive Crayfish Threaten the Development of Submerged Macrophytes in Lake Restoration

et al. 2013

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Submerged macrophytes enhance water transparency and aquatic biodiversity in shallow water ecosystems. Therefore, the return of submerged macrophytes is the target of many lake restoration projects. However, at present, north-western European aquatic ecosystems are increasingly invaded by omnivorous exotic crayfish. We hypothesize that invasive crayfish pose a novel constraint on the regeneration of submerged macrophytes in restored lakes and may jeopardize restoration efforts. We experimentally investigated whether the invasive crayfish (Procambarus clarkii Girard) affects submerged macrophyte development in a Dutch peat lake where these crayfish are expanding rapidly. Seemingly favourable abiotic conditions for macrophyte growth existed in two 0.5 ha lake enclosures, which provided shelter and reduced turbidity, and in one lake enclosure iron was added to reduce internal nutrient loading, but macrophytes did not emerge. We transplanted three submerged macrophyte species in a full factorial exclosure experiment, where we separated the effect of crayfish from large vertebrates using different mesh sizes combined with a caging treatment stocked with crayfish only. The three transplanted macrophytes grew rapidly when protected from grazing in both lake enclosures, demonstrating that abiotic conditions for growth were suitable. Crayfish strongly reduced biomass and survival of all three macrophyte species while waterfowl and fish had no additive effects. Gut contents showed that crayfish were mostly carnivorous, but also consumed macrophytes. We show that P. clarkii strongly inhibit macrophyte development once favourable abiotic conditions for macrophyte growth are restored. Therefore, expansion of invasive crayfish poses a novel threat to the restoration of shallow water bodies in north-western Europe. Prevention of introduction and spread of crayfish is urgent, as management of invasive crayfish populations is very difficult.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Invasive Crayfish Threaten the Development of Submerged Macrophytes in Lake Restoration

et al. 2013

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“…Lake Terra Nova (85 ha) is a shallow eutrophic peat lake, while Lake Waterleidingplas (160 ha) is a shallow mesotrophic lake with a sand bottom. Lake Waterleidingplas is used as a drinking water reservoir and has good water quality, whereas Lake Terra Nova is used for water storage and has undergone intensive restoration management to improve its water quality and biodiversity (Ter Heerdt and Hootsmans, 2007 ; Immers et al, 2015 ).…”

Section: Methodsmentioning

confidence: 99%

High Grazing Pressure of Geese Threatens Conservation and Restoration of Reed Belts

Bakker

Veen

Heerdt³

et al. 2018

Front. Plant Sci.

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Reed (Phragmites australis (Cav.) Trin. ex Steud.) beds are important habitat for marsh birds, but are declining throughout Europe. Increasing numbers of the native marsh bird, the Greylag goose (Anser anser L.), are hypothesized to cause reed bed decline and inhibit restoration of reed beds, but data are largely lacking. In this study, we experimentally tested the effect of grazing by Greylag geese on the growth and expansion of reed growing in belts along lake shorelines. After 5 years of protecting reed from grazing with exclosures, reed stems were over 4-fold denser and taller than in the grazed plots. Grazing pressure was intense with 50–100% of the stems being grazed among years in the control plots open to grazing. After 5 years of protection we opened half of the exclosures and the geese immediately grazed almost 100% of the reed stems. Whereas this did not affect the reed stem density, the stem height was strongly reduced and similar to permanently grazed reed. The next year geese were actively chased away by management from mid-March to mid-June, which changed the maximum amount of geese from over 2300 to less than 50. As a result, reed stem density and height increased and the reed belt had recovered over the full 6 m length of the experimental plots. Lastly, we introduced reed plants in an adjacent lake where no reed was growing and geese did visit this area. After two years, the density of the planted reed was six to nine-fold higher and significantly taller in exclosures compared to control plots where geese had access to the reed plants. We conclude that there is a conservation dilemma regarding how to preserve and restore reed belts in the presence of high densities of Greylag geese as conservation of both reed belts and high goose numbers seems infeasible. We suggest that there are three possible solutions for this dilemma: (1) effects of the geese can be mediated by goose population management, (2) the robustness of the reed marshes can be increased, and (3) at the landscape level, spatial planning can be used to configure landscapes with large reed bed reserves surrounded by unmown, unfertilized meadows.

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“…Removal of fish stock was suggested in some studies as a means of attempting to control eutrophication (Shapiro 1990; Jeppesen et al . 1997; Heerdt & Hootsmans 2007). Thus, a strategy of fish stocking was applied to Lake Rupa, which exhibited extensive growths of aquatic vegetation, to the extent that the lake was beginning to be transformed into swampy land.…”

Section: Discussionmentioning

confidence: 99%

Restoration of small lakes through cooperative management: A suitable strategy for poverty‐laden areas in developing countries?

Gurung¹

2007

Lakes & Reservoirs

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Lake Rupa is a small, subtropical, shallow lake with a surface area of 100 ha situated 600 m a.s.l. in Central Himalaya, Nepal. This degraded lake was studied between 2000 and 2006, with the goal of determining whether or not it could be restored by a community-based cooperative of local people living in its catchment. Main threats to the lake, its aquatic life and its very existence include encroachment by excessive aquatic vegetation, sedimentation, and low in-lake concentrations of dissolved oxygen (DO). Small lakes (≤ 500 ha) are relatively prone to the process of 'succession and climax', although they also can be of social, environmental and ecological importance. Thus, their disappearance could spark social chaos and disorder in areas already having to cope with other rapid environmental changes. This means that credible mechanisms for revitalizing or protecting small lakes are an important goal. Accordingly, a lake cooperative of 329 households living in close vicinity to Lake Rupa was formed in 2002, by prioritizing traditional fishers, women and other deprived community members with the goals of respecting the citizenry and equity. Following the cooperative's campaigns directed at weed removal and fish stocking, encroachment of vegetation on the lake margins was halted, its aquatic weeds became under control, and its fisheries improved. In addition to the cooperative's restoration activities, several water quality parameters, including water transparency and DO and chlorophyll-a concentrations, were monitored on a monthly basis. The measured water transparency was inconsistent, exhibiting large variations between 2000 and 2003. Relatively low, but consistent, values, however, were measured after 2004. The results imply that the removal of weeds, and sufficient nutrients and solar radiation are subsequently available to the lake's phytoplankton communities. Supporting this notion is that the chlorophyll-a concentration spiked to 205 µg L -1 in November 2006, the water transparency became consistent, and the DO concentration increased to >3.8 mg L -1 during the critical months (March-May) after 2004. These water quality indicators indicated improvement in the degraded Lake Rupa, suggesting that the establishment of cooperatives such as that highlighted in this study could be a powerful and sustainable mechanism for restoring degraded lakes in similar socioeconomic settings by maintaining equity, by connecting communities with their resources, and by facilitating integrity, equity, citizenry and social justice.

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Why biomanipulation can be effective in peaty lakes

Cited by 26 publications

References 35 publications

Invasive Crayfish Threaten the Development of Submerged Macrophytes in Lake Restoration

Invasive Crayfish Threaten the Development of Submerged Macrophytes in Lake Restoration

High Grazing Pressure of Geese Threatens Conservation and Restoration of Reed Belts

Restoration of small lakes through cooperative management: A suitable strategy for poverty‐laden areas in developing countries?

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