The biogeochemical implications of massive gull flocks at landfills

Winton, R. Scott; River, Mark

doi:10.1016/j.watres.2017.05.076

Cited by 16 publications

(23 citation statements)

References 34 publications

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“…The landfills used by LBBGs roosting at FP were created between 1986 and 2006, a period that coincides with the increase in the numbers of LBBG wintering in Andalusia. Similar effects have been observed in North America, where the creation of landfills has resulted in increased gull populations and guanotrophic effects (Winton & River, ).…”

Section: Discussionsupporting

confidence: 69%

“…Our study reveals a massive translocation of nutrients from landfills to a natural, protected lake by roosting gulls (see Winton & River, for similar examples in North America). Gulls spent most time at the Matagrande and Montalbán landfills (both in terms of total time and time per visit) at an intermediate distance.…”

Section: Discussionmentioning

confidence: 55%

“…For these calculations, we assumed that LBBGs have a mean body mass of 792 g (Hahn et al., ) and a daily energy requirement of 968.66 kJ (Nagy, Girard, & Brown, ). We adopted values of food energy content of 23.9 kJ/g based on landfill diet (Winton & River, ), a metabolisable energy coefficient of 0.76 (Karasov, ), and an intake: excretion ratio of 0.395 (Dobrowolski, Kozakiewicz, & Leźnicka, ; Nixon & Oviatt, ). ER pellets = egestion rate of pellets per day. One pellet is assumed to be produced per day (Lovas‐Kiss et al., ), and deposited within the roosting site. PW = mean pellet weight.…”

Section: Methodsmentioning

confidence: 99%

“…Guanotrophy studies rely partly on estimates of body mass functions and daily food intake to model the nutrient loading to wetlands (Hahn, Bauer, & Klaassen, , ). These models also rely on waterbird counts at wetland roosts and assumptions about the proportion of time that birds spend in the wetland, which has a direct influence on the proportion of daily faecal output egested there (Hahn et al., ; Winton & River, ). However, tracking daily movements of individuals allows the quantification of time use and movements between feeding and roosting sites that can then complement censuses and help to quantify nutrient loading.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, we expect higher gull numbers and longer roosting time at intermediate water levels; (3) movement data allow us to identify different open landfills used as feeding sites by the gulls roosting at FP, and allow us to quantify their relative importance for nutrient loading; (4) regurgitated pellets represent an important fraction of the contribution of LBBGs to the nutrient budget of FP. Pellets are produced regularly by LBBG at roost sites (Lovas‐Kiss et al., ), yet have been overlooked in previous guanotrophy studies (Winton & River, ).…”

Section: Introductionmentioning

confidence: 99%

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Quantifying nutrient inputs by gulls to a fluctuating lake, aided by movement ecology methods

et al. 2019

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Eutrophication of aquatic ecosystems is a global problem with major ecological and economic impacts. In many lakes and reservoirs, guanotrophication occurs when roosting waterbirds import nutrients (nitrogen and phosphorus) from surrounding terrestrial habitats. To date, nutrient loading by waterbirds has been estimated based on censuses in the absence of detailed information on their movements. We quantified nutrient importation by the lesser black‐backed gull (Larus fuscus) to Fuente de Piedra (1,350 ha) in Andalusia (south‐west Spain), where an average of 36,288 individuals are counted in January. During seven winters from 2010 to 2017, we used movement data from 20 individual gulls tagged with Global Positioning System trackers that foraged in four landfills. Together with monthly bird counts and measurements of total N and P content in faeces and pellet samples, movement data were used to quantify the total external loading effect for different winters. Movement data allowed us to quantify the proportion of time spent in the lake and the time spent at different foraging sites and enabled correction of censuses. According to tracking data, on average 69% of the birds had already left the lake to head for feeding sites when waterbird counts were carried out. Nutrient inputs to the lake depend partly on the proportion of the day that gulls spend there, which was higher in late winters and was reduced when lake depth went below or above 20–35 cm. An estimated average of 10.17 kg N ha−1 year−1 and 2.07 kg P ha−1 year−1 were imported to this closed‐basin lake by gulls each winter, with highest values recorded in winter 2016–2017. Gull guano is the most important winter source of nutrients to the lake. Regurgitated pellets have been ignored as a source of nutrients in other guanotrophy studies, but we found them to be a more important source of P than faeces. A movement ecology approach complements traditional censuses and facilitates the study of guanotrophication in multiple ways, including identification of sources of nutrients, correction of censuses, and measuring time spent at roost sites.

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Section: Discussionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 55%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Quantifying nutrient inputs by gulls to a fluctuating lake, aided by movement ecology methods

et al. 2019

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Guanotrophication by Waterbirds in Freshwater Lakes: A Review on Ecosystem Perspective

Adhurya

Das

Ray

2020

Mathematical Analysis and Applications in Modeling

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Are increasing roosting waterbird numbers responsible for eutrophication of shallow lakes? Examples from a Danish Ramsar site

Clausen,

Lauridsen,

Pedersen

et al. 2024

Hydrobiologia

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The Water Framework Directive (WFD) requires actions from European Union Member States to reduce external nutrient loading in lakes of moderate/poor/bad ecological status and restore their good ecological status. Several poor-quality Danish lakes have been exempted from WFD criteria (and more proposed), due to suspected major imported nutrient contributions from waterbirds, without supporting evidence. Here, we estimated relative nutrient contributions from increasing numbers of roosting waterbirds compared to total nutrient loadings in four brackish lakes (43–491 ha) at an internationally important Ramsar site/EU Birds Directive Special Protection Area. Combining night- and daytime counts of roosting numbers of the most numerous species with intake and faecal output models, we estimated roosting birds (mostly geese) contributed 0.2–0.4% of all N inputs (0.3–1.2 kg N/ha/year) and 0.6–2.0% of all P inputs (0.04–0.12 kg P/ha/year) in three lakes (one of which has been proposed exempted from WFD criteria), but potentially as high as 14% and 76%, respectively, at a fourth clearwater lake without direct inflow or outlets. These results confirm the need for case-by-case assessments of avian nutrient import relative to total nutrient balance before exempting lakes from WFD conditions due to supposed natural loading from waterbirds.

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The biogeochemical implications of massive gull flocks at landfills

Cited by 16 publications

References 34 publications

Quantifying nutrient inputs by gulls to a fluctuating lake, aided by movement ecology methods

Quantifying nutrient inputs by gulls to a fluctuating lake, aided by movement ecology methods

Guanotrophication by Waterbirds in Freshwater Lakes: A Review on Ecosystem Perspective

Are increasing roosting waterbird numbers responsible for eutrophication of shallow lakes? Examples from a Danish Ramsar site

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