Long-Term Changes in Nutrients and Mussel Stocks Are Related to Numbers of Breeding Eiders Somateria mollissima at a Large Baltic Colony

Laursen, Karsten; Møller, Anders Pape

doi:10.1371/journal.pone.0095851

Cited by 36 publications

(44 citation statements)

References 28 publications

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“…These changes have negative consequences for bird populations (Bryhn and others 2009). The hypothetical mechanisms linking change in population size of waterbirds to leakage of fertilizer to the marine environment is supported by a recent study of the abundance of blue mussel and its main consumer the eider (Laursen and Møller 2014). Fertilizer use on farmland resulted in increased concentrations of phosphorus, which caused an increase in the production of phytoplankton, which in turn were consumed by mussels.…”

Section: Population Trends and Fertilizer Usementioning

confidence: 99%

“…The addition of nitrogen and phosphorus to marine environments has increased the abundance of benthos (Nixon and Buckley 2002). Laursen and Møller (2014) have recently shown that increased abundance of nutrients in the marine environment caused by leaching from farmland increased the abundance of blue mussels, Mytilus edulis.…”

Section: Introductionmentioning

confidence: 99%

“…Finally, the duration of the breeding season of four species of terns was reduced with increasing amounts of Fertilizer and Marine Ecosystems nutrients (Møller and others 2010). Similarly, eiders Somateria mollissima are consumers of blue mussels and other benthos with nutrients increasing the abundance of mussels which in turn shows a delayed effect on the size of the breeding populations (Laursen and Møller 2014).…”

Section: Introductionmentioning

confidence: 99%

“…As a prime example, the breeding population of eiders increased with amount of fertilizer from index values of 75-400 (1950 = 100) followed by a decrease in population size when fertilizer use declined from 400 to 250 (Laursen and Møller 2014). Therefore, the effects of nutrients are reversible.…”

Section: Introductionmentioning

confidence: 99%

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Fertilizer Leakage to the Marine Environment, Ecosystem Effects and Population Trends of Waterbirds in Denmark

Møller

Flensted-Jensen²,

Laursen

et al. 2014

Ecosystems

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Leakage of nutrients from farmland to freshwater and marine environments results in fertilization that increases primary production with cascading effects in the ecosystem. Leakage of fertilizers may initially increase availability of food for primary and secondary consumers, although part of this effect may subsequently be followed by a reduction in food abundance caused by hypoxia. We hypothesized that leakage of nutrients from farmland increased primary and secondary production and subsequently the population size of waterbirds. The amount of phosphorus in the marine environment in Denmark during 1975-2010 increased with fertilizer use on farmland and this effect was stronger when winter precipitation was high. Leakage of fertilizer had ecosystem effects on phytoplankton, zooplankton, and ultimately biodiversity in the marine environment. We found linear relationships between fertilizer use and population size of breeding and wintering waterbirds, with additional quadratic relationships with fertilizer use and linear effects of temperature. The linear effect of fertilizer use depended on the diet of waterbirds with stronger effects in herbivorous and piscivorous species than in species eating benthos. These findings have implications for management of waterbird populations because a reduction in fertilizer use should result in increasing populations of herbivores and piscivores.

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Section: Population Trends and Fertilizer Usementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fertilizer Leakage to the Marine Environment, Ecosystem Effects and Population Trends of Waterbirds in Denmark

Møller

Flensted-Jensen²,

Laursen

et al. 2014

Ecosystems

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“…Like other seaducks (Mergini), common eider spring arrival responded to local weather parameters, ice cover, the North Atlantic Oscillation (NAO) index and fertilizer release Jónsson et al 2009;Love et al 2010;Zipkin et al 2010;Laursen and Møller 2014). In northwest Iceland, spring icecover generally is absent but females arrived later following warm winters with strong westerly winds (positive NAO values; Jónsson et al 2009), whereas females in southwest Iceland nested earlier following milder winters (D'Alba et al 2010).…”

Section: Introductionmentioning

confidence: 94%

The early birds and the rest: do first nesters represent the entire colony?

Jónsson

Lúðvíksson²,

Kaller

2016

Polar Biol

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Climate change studies have detected earlier spring arrival of breeding birds. However, first nest dates (date first nests were found), which commonly provide the metric for earlier arrival, can be biased by population size or sampling effort. Our aims were to determine if: 1) first nest dates and median nest date (date when at least 50 % of all females have nested) were equivalent predictors for the spring arrival and 2) first nest date or median nest date were related to nest numbers. We recorded first and median nest dates and nest numbers at the common eider (Somateria mollissima) colony at Rif, Iceland, during 1992-2013. First nest date was advanced by 11 days during the study, but median nest date was advanced by only 4 days. First nest date and median nest date were correlated, but this relationship was only a small improvement over the null model (Nagelkerke R 2 = 30 %). We found a relationship with nest count for both first and median nest dates once the analysis had accounted for inter-annual variability. First nest date may not represent the colony as a whole but rather the physically fittest or the most determined individuals, which may be more prone to nest early than the general population. Nesting birds must decide how much to advance breeding based on nest numbers and other nontemporal cues which necessitate earlier breeding. We argue that nest numbers affect the birds in a biological sense and that the advancement was not explained solely by increased nest numbers.

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Predation and nutrients drive population declines in breeding waders

Møller

Thorup²,

Laursen

2018

Ecological Applications

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Allee effects are defined as a decline in per capita fitness at low population density. We hypothesized that predation reduces population size of breeding waders and thereby the efficiency of predator deterrence, while total nitrogen through its effects on primary and secondary productivity increases population size. Therefore, nest predation could have negative consequences for population size because nest failure generally results in breeding dispersal and hence reduced local population density. To test these predictions, we recorded nest predation in five species of waders for 4,745 nests during 1987-2015 at the nature reserve Tipperne, Denmark. Predation rates were generally negatively related to conspecific and heterospecific population density, but positively related to overall population density of the entire wader community. Nest predation and population density were related to ground water level, management (grazing and mowing), and nutrients. High nest predation with a time lag of one year resulted in low overall breeding population density, while high nutrient levels resulted in higher population density. These two factors accounted for 86% of the variance in population size, presumably due to effects of nest predation on emigration, while nutrient levels increased the level of vegetation cover and the abundance of food in the surrounding brackish water. These findings are consistent with the hypothesis that predation may reduce population density through negative density dependence, while total nitrogen at adjacent shallow water may increase population size. Nest predation rates were reduced by high ground water level in March, grazing by cattle and mowing that affected access to and susceptibility of nests to predators. These effects can be managed to benefit breeding waders.

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Long-Term Changes in Nutrients and Mussel Stocks Are Related to Numbers of Breeding Eiders Somateria mollissima at a Large Baltic Colony

Cited by 36 publications

References 28 publications

Fertilizer Leakage to the Marine Environment, Ecosystem Effects and Population Trends of Waterbirds in Denmark

Fertilizer Leakage to the Marine Environment, Ecosystem Effects and Population Trends of Waterbirds in Denmark

The early birds and the rest: do first nesters represent the entire colony?

Predation and nutrients drive population declines in breeding waders

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