Monthly Abundance Patterns and the Potential Role of Waterbirds as Phosphorus Sources to a Hypertrophic Baltic Lagoon (original) (raw)
Related papers
Estimating the contribution of carnivorous waterbirds to nutrient loading in freshwater habitats
Freshwater Biology, 2007
1. We estimated nitrogen (N) and phosphorus (P) loading into wetlands by carnivorous waterbirds with alternative physiological models using a food-intake and an excretaproduction approach. The models were applied for non-breeding and breeding Dutch inland carnivorous waterbird populations to quantify their contribution to nutrient loading on a landscape scale. 2. Model predictions based on food intake exceeded those based on excretion by 59-62% for N and by 2-36% for P, depending on dietary assumptions. Uncertainty analysis indicated that the intake model was most affected by errors in energy requirement, while the excretion model was dependent on faecal nutrient composition. 3. Per capita loading rate of non-breeders increased with body mass from 0.3-0.8 g N day )1 and 0.15 g P day )1 in little gulls Larus minutus to 4.5-11.5 g N day )1 and 2.1-3.2 g P day )1 in great cormorants Phalacrocorax carbo. For breeding birds, the estimated nutrient loading by a family unit over the entire breeding period ranged between 17.6-443.0 g N and 8.6 g P for little tern Sterna albifrons to 619.6-1755.6 g N and 316.2-498.1 g P for great cormorants. 4. We distinguished between external (i.e. importing) and internal (i.e. recycling) nutrient loading by carnivorous waterbirds. For the Netherlands, average external-loading estimates ranged between 38.1-91.5 tonnes N and 16.7-18.2 tonnes P per year, whilst internal-loading estimates ranged between 53.1-140.5 tonnes N and 25.2-39.2 tonnes P and per year. The average contribution of breeding birds was estimated to be 17% and 32% for external and internal loading respectively. Most important species were black-headed gull Larus ridibundus and mew gull Larus canus for external loading, and great cormorant and grey heron Ardea cinerea for internal loading. 5. On a landscape scale, loading by carnivorous waterbirds was of minor importance for freshwater habitats in the Netherlands with 0.26-0.65 kg N ha )1 a )1 and 0.12-0.16 kg P ha )1 a )1 . However, on a local scale, breeding colonies may be responsible for significant P loading.
Lakes and Reservoirs: Research and Management, 2008
The Mar Menor, a 135-km2 saline lake, is the largest water surface on the western Mediterranean coast, and an internationally important bird area. It is surrounded by a large irrigated agricultural plain, with dense tourism developments. Although the impacts of these activities on water quality are locally evident, their effects on waterbird populations are poorly known. In the winter 2004–2005, we studied the distribution of four waterbird species (Podiceps cristatus, Podiceps nigricollis, Phalacrocorax carbo and Fulica atra) around the main drainage channel that discharges into the lake, where it was feasible to infer spatial patterns of eutrophication (alongshore and shore centre) from previous environmental surveys. Waterbirds were counted along a stretch of undeveloped shoreline extending southwards from the channel outlet, in contiguous sections, and in bands parallel to the shoreline. Linear mixed models (LMM) indicated the population density increased only markedly for grebes (Podiceps cristatus, Podiceps nigricollis) and coot (Fulica atra) in littoral bands qualifying as eutrophic, but not an alongshore response, with their finescale alongshore distribution being apparently unrelated to nutrient sources. Considering the whole lake, however, the temporal trends and distribution of the wintering populations indicated that waterbirds respond numerically, in a guild-specific way, to nutrient inputs. Grebes and coot could be a useful ‘two-stage’ warning signal for potential problem areas affected by similar influences.
Waterbirds and nutrient enrichment in Mar Menor Lagoon, a shallow coastal lake in southeast Spain
2008
The Mar Menor, a 135-km 2 saline lake, is the largest water surface on the western Mediterranean coast, and an internationally important bird area. It is surrounded by a large irrigated agricultural plain, with dense tourism developments. Although the impacts of these activities on water quality are locally evident, their effects on waterbird populations are poorly known. In the winter 2004-2005, we studied the distribution of four waterbird species (Podiceps cristatus, Podiceps nigricollis, Phalacrocorax carbo and Fulica atra) around the main drainage channel that discharges into the lake, where it was feasible to infer spatial patterns of eutrophication (alongshore and shore centre) from previous environmental surveys. Waterbirds were counted along a stretch of undeveloped shoreline extending southwards from the channel outlet, in contiguous sections, and in bands parallel to the shoreline. Linear mixed models (LMM) indicated the population density increased only markedly for grebes (Podiceps cristatus, Podiceps nigricollis) and coot (Fulica atra) in littoral bands qualifying as eutrophic, but not an alongshore response, with their finescale alongshore distribution being apparently unrelated to nutrient sources. Considering the whole lake, however, the temporal trends and distribution of the wintering populations indicated that waterbirds respond numerically, in a guild-specific way, to nutrient inputs. Grebes and coot could be a useful 'two-stage' warning signal for potential problem areas affected by similar influences.
Quantification of allochthonous nutrient input into freshwater bodies by herbivorous waterbirds
Freshwater Biology, 2007
1. Waterbirds are considered to import large quantities of nutrients to freshwater bodies but quantification of these loadings remains problematic. We developed two general models to calculate such allochthonous nutrient inputs considering food intake, foraging behaviour and digestive performance of waterbirds feeding in terrestrial habitats: an intake model (IM), mainly based on an allometric relationship for energy requirements and a dropping model (DM), based on allometric relationships for defaecation.2. Reviewed data of nitrogen (N) and phosphorus (P) content of herbivorous food varied according to diet type (foliage, seeds and roots), season and fertilization. For model parameterization average foliage diet contained 38.20 mg N g−1 and 3.21 mg P g−1 (dry weight), whereas mean faeces composition was 45.02 mg N g−1 and 6.18 mg P g−1.3. Daily allochthonous nutrient input increased with body mass ranging from 0.29 g N and 0.03 g P in teals Anas crecca to 5.69 g N and 0.57 g P in mute swans Cygnus olor. Results from IM differed from those of DM from ducks to swans by 63–108% for N and by −4 to 23% for P. Model uncertainty was lowest for the IM and mainly caused by variation in estimates of food retention time (RT). In DM food RT and dropping mass determined model uncertainty in similar extent.4. Exemplarily applying the models to Dutch wetlands resulted in mean annual contribution of herbivorous waterbirds to allochthonous nutrient loading of 382.8 ± 167.1 tonnes N a−1and 34.7 ± 2.3 tonnes P a−1, respectively, which corresponds to annual surface-water loadings of 1.07 kg N ha−1 and 0.10 kg P ha−1.5. There was a distinct seasonal pattern with peak loadings in January, when bird abundances were highest. Lowest inputs were in August, when bird abundance and nutrient content in food was low and birds foraged less in terrestrial habitats. Three-quarters of all nutrient input was contributed by greater white-fronted goose Anser albifrons, greylag goose Anser anser, wigeon Anas penelope and barnacle goose Branta leucopsis alone.6. We provide general, easy to use calculation methods for the estimation of allochthonous nutrient inputs by waterbirds, which are applicable to a range of waterbird species, a variety of potential diets and feeding behaviours, and across spatial scales. Such tools may greatly assist in the planning and execution of management actions for wetland nutrient budgets.
Ecological Indicators, 2011
a b s t r a c t Southern Mediterranean lagoons are among the more vulnerable systems regarding human activities (e.g. agriculture, tourism, urbanization) leading to eutrophication. We analyse the relationship of waterbirds with locally measured or modelled environmental variables (nutrient load, fish production, jellyfish blooms) related with this process, in the Mar Menor lagoon (Murcia, SE Spain), and discuss the potential value of birds as indicators of the trophic status of the wetland. We use GLMs to relate the biomass of the five most abundant and representative waterbird species to these variables, accounting for the potential influence of external factors affecting their population at higher biogeographical scales. A significant effect of such factors was only found for Great Cormorant, which biased the positive response of the piscivore guild to nutrient load (NLD). Red-breasted Merganser appeared relatively insensitive to nutrient enrichment, although declined in the long term. The remaining species responded positively, NLD being a significant predictor of their biomass when a 2-year lag was allowed, although this variable alone had a low explanatory power except for the Coot. When homogeneous temporal phases were defined, grebes could be identified as early warners of eutrophication, and Coot as late-stage ones. The increase of piscivores along a period of declining fish catches could reflect a shift in fish community composition or structure that favours their feeding preferences. The interactive role of jellyfish, buffering temporally the loading of nutrients, may also be related to these changes.
Seabird colonies as important global drivers in the nitrogen and phosphorus cycles
Nature communications, 2018
Seabirds drastically transform the environmental conditions of the sites where they establish their breeding colonies via soil, sediment, and water eutrophication (hereafter termed ornitheutrophication). Here, we report worldwide amounts of total nitrogen (N) and total phosphorus (P) excreted by seabirds using an inventory of global seabird populations applied to a bioenergetics model. We estimate these fluxes to be 591 Gg N yand 99 Gg P y, respectively, with the Antarctic and Southern coasts receiving the highest N and P inputs. We show that these inputs are of similar magnitude to others considered in global N and P cycles, with concentrations per unit of surface area in seabird colonies among the highest measured on the Earth's surface. Finally, an important fraction of the total excreted N (72.5 Gg y) and P (21.8 Gg y) can be readily solubilized, increasing their short-term bioavailability in continental and coastal waters located near the seabird colonies.
Environmental Science and Pollution Research, 2023
Waterbirds depend on a dispersed network of wetlands for their annual life cycle during migration. Climate and land use changes raise new concerns about the sustainability of these habitat networks, as water scarcity triggers ecological and socioeconomic impacts threatening wetland availability and quality. During the migration period, birds can be present in large enough numbers to influence water quality themselves linking them and water management in efforts to conserve habitats for endangered populations. Despite this, the guidelines within laws do not properly account for the annual change of water quality due to natural factors such as the migration periods of birds. Principal component analysis and principal component regression was used to analyze the correlations between the presence of a multitude of migratory waterbird communities and water quality metrics based on a dataset collected over four years in the Dumbrăvița section of the Homoród stream in Transylvania. The results reveal a correlation between the presence and numbers of various bird species and the seasonal changes in water quality. Piscivorous birds tended to increase the phosphorus load, herbivorous waterbirds the nitrogen load, while benthivorous duck species influenced a variety of parameters. The established PCR water quality prediction model showed accurate prediction capabilities for the water quality index of the observed region. For the tested data set, the method provided an R 2 value of 0.81 and a mean squared prediction error of 0.17.
During the period 1980–2000, the yellow-legged gull population underwent exponential growth due to an increase in the availability of anthropogenic food resources. The aim of this study was to highlight the effect of the gull colonies on the P soil cycle and the associated effects on coastal ecosystems. Samples of soil, water and faecal material were collected in a colony of yellow-legged gulls (Cíes Islands) and in a control area. Four sampling plots were installed in the study areas, and samples were collected in summer and winter in 1997 and 2011. Sample analysis included soil characterization and determination of the total P content (TP), bioavailable-P and fractionated-P forms in the soils and faecal material. The 31P NMR technique was also used to determine organic P forms. Clear differences between the gull colony soils and the control soilwere observed. The TP was 3 times higher in the gull colony soil, and the bioavailable P was 30 times higher than in the control soil. The P forms present at highest concentrations in the faecal material (P-apatite, P-residual and P-humic acid) were also present at high concentrations in the colony soil. The absence of any seasonal or annual differences in P concentration indicates that the P has remained stable in the soil over time, regardless of the changes in the gull population density. The degree of P saturation indicated that soils are saturated with P due to the low.
Hydrobiologia, 2005
The Mar Menor is the largest coastal lagoon in the Western Mediterranean and it is an important site for wintering and breeding waterfowl. During recent decades several hydrological and land-use changes in the watershed have increasingly threatened the conservation of the lagoon due to the development of urban areas, tourism and agriculture. A dynamic system model has been developed at the watershed scale to estimate the annual load of nutrients reaching the Mar Menor-associated wetlands. At present, mean annual loadings of approximately 2000 tonnes of nitrogen and 60 tonnes of phosphorus are delivered to the lagoon. The simulation results emphasize the role of heavy rainfall events and floods in the formation of the total nutrient load. The composition of aquatic bird communities has been used to assess the nutrient impact on the lagoon food-web. The Great Crested Grebe is apparently the species most closely dependant on local trophic conditions. The related Black-necked Grebe, that dominates the waterbird community of the lagoon, plays a similar role, but its more opportunistic response to changes in food resources, reduces its indicator value. The abundance of the two species of grebes seems to closely track the nitrogen load curve, especially during the first phase of enrichment, suggesting the existence of a direct trophic relationship. In the following phase, jellyfish blooms coincide with the bird decline. Jellyfishes seem to have a buffering effect towards nutrients, determining a bottom up limitation to other trophic compartments. In recent years, this buffering capacity has probably been overloaded, favouring the growth of new food resources available to the grebes. Unlike grebes, Mergus serrator, a typical piscivorous bird, does not seem to be affected positively by eutrophication since it shows a long-term stability in numbers or even a slight decline. Since this suspected decline would parallel a long-term reduction of fish catches, the species could be regarded as a potential indicator of habitat deterioration. Hydrobiologia (2005) 550:221-235 Ó Springer 2005 P. Viaroli, M. Mistri, M.
Oceanological and Hydrobiological Studies, 2014
Large numbers of Mallard Anas platyrhynchos (max. 10,490 ind.), Black-headed Gull Chroicocephalus ridibundus (max. 3,430 ind.) and Great Cormorant Phalacrocorax carbo (max. 1,449 ind.) were recorded on the Goczałkowice Reservoir, Poland (2,754 ha). Most of the waterbirds occurred in the backwater of this reservoir. The amount of phosphorus and nitrogen loaded by the most numerous waterbirds into Goczałkowice Reservoir was estimated at 958 kg and 2,621 kg, respectively in 2011 and 1,043 kg and 2,793 kg, respectively in 2012. In 2011 and 2012, the waterbirds introduced a considerable amount of phosphorus, nitrogen and a large number of coliforms into the backwater of the reservoir. The concentration of different forms of phosphorus and nitrogen, chlorophyll-a and bacteria coli in the water was not greater at the site of birds' concentration (except dissolved organic nitrogen). The concentration of nitrates in the * Corresponding author: gwiazda@iop.krakow.pl