Birds as eutrophicating agents: a nutrient budget for a small lake in a protected area

Chaichana, Ratcha; Leah, R.T.; Moss, Brian

doi:10.1007/s10750-010-0166-2

Cited by 52 publications

(23 citation statements)

References 34 publications

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“…Bird impact without food quality (q = 1, grey lines) is shown for comparison. At a density of 50 coots ha -1 , macrophytes were not present for any of the P loadings Hydrobiologia (2016) 777:197-207 203 droppings, thereby contributing to eutrophication directly (Hahn et al, 2008;Chaichana et al, 2010). Another mechanism by which the impact of coots could be larger than predicted by PCLake is nonconsumptive destruction of macrophytes while foraging on invertebrates (Paillisson & Marion, 2001).…”

Section: Discussionmentioning

confidence: 98%

The impact of bird herbivory on macrophytes and the resilience of the clear-water state in shallow lakes: a model study

et al. 2016

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Shallow lakes have the potential to switch between two alternative stable states: a clear macrophyte-dominated and a turbid phytoplankton-dominated state. Observational and experimental studies show that in some lakes herbivory by birds may severely decrease macrophyte biomass, while in other lakes, the removed biomass by herbivory is compensated by regrowth. These contradictory outcomes might arise because of interplay between top-down control by bird herbivory and bottom-up effects by nutrient loading on macrophytes. Here, we use the ecosystem model PCLake to study top-down and bottom-up control of macrophytes by coots and nutrient loading. Our model predicted that (1) herbivory by birds lowers the critical nutrient loading at which the regime shift occurs; (2) bird impact on macrophyte biomass through herbivory increases with nutrient loading; and (3) improved food quality enhances the impact of birds on macrophytes, thus decreasing the resilience of the clear-water state even further. The fact that bird herbivory can have a large impact on macrophyte biomass and can facilitate a regime shift implies that the presence of waterfowl should be taken into account in the estimation of critical nutrient loadings to be used in water quality management.

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Section: Discussionmentioning

confidence: 98%

The impact of bird herbivory on macrophytes and the resilience of the clear-water state in shallow lakes: a model study

et al. 2016

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“…The capacity for waterfowl to serve as nutrient vectors has been studied across a variety of aquatic habitats (Chaichana et al 2010;Manny et al 1994;Olson et al 2005;Post et al 1998). Waterfowl at Lake Mattamuskeet, particularly Snow Goose (Chen caerulescens) and Tundra Swan (Cygnus columbianus), feed in adjacent wetland or agricultural habitats, but return to the Lake to roost where their defecation represents an allochthonous source of N. While we lack highresolution quantitative data on the movement of all species of waterfowl, we observed a consistent daily influx of geese, Tundra Swan, and ducks into the lake and impoundments at dusk.…”

Section: Bird Transportmentioning

confidence: 99%

Waterfowl Impoundments as Sources of Nitrogen Pollution

Winton

Moorman

Richardson

2016

Water Air Soil Pollut

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Hydrologically controlled moist-soil impoundment wetlands provide critical habitat for high densities of migratory bird populations. Nutrients exported from heavily used impoundments by prescribed seasonal drawdown of surface water may contribute to the eutrophication of aquatic ecosystems. To investigate the relative importance of nutrient export from managed impoundment habitats, we conducted a field study at Mattamuskeet National Wildlife Refuge in North Carolina, USA, which contains 1545 ha of impoundments that drain into hypereutrophic Lake Mattamuskeet. We found that prescribed hydrologic drawdowns of an impoundment exported roughly the same amount of nitrogen (N) as adjacent fertilized agricultural fields on a per-area basis and contributed approximately one fifth of total N load to Lake Mattamuskeet. The prescribed drawdown regime, designed to maximize waterfowl production in impoundments, may be exacerbating the degradation of habitat quality in the downstream lake as an unintended consequence. Few studies of wetland N dynamics have targeted impoundments managed to provide wildlife habitat, but a similar phenomenon may occur in some of the 36,000 ha of similarly managed moist-soil impoundments on National Wildlife Refuges in the southeastern USA, especially those hosting dense concentrations of waterfowl. We suggest an earlier seasonal drawdown could potentially mitigate impoundment N pollution and estimate it could reduce N export from our study impoundment by more than 70 %.

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“…We found that dense congregation of waterfowl, mainly Canada geese, raised ammonium concentrations in pool 6 in winter 2004 (Chaichana et al, 2010). Solid wastes excreted by water birds in winter may subsequently affect water chemistry in summer as they decompose.…”

Section: Water Quality and Nutrient Sources And Movementsmentioning

confidence: 81%

“…Solid wastes excreted by water birds in winter may subsequently affect water chemistry in summer as they decompose. Nutrient budgets for pool 6 showed substantial release of phosphorus and ammonium from the sediments in summer and birds were the major external loading source of phosphorus (Chaichana et al, 2010). This effect is unlikely to extend to other pools as there were much greater species numbers and densities of waterfowl on pool 6 than in the smaller pools 3 and 14.…”

Section: Water Quality and Nutrient Sources And Movementsmentioning

confidence: 92%

“…The external nutrient budget of the main pool (number 6) is dominated by bird inputs (Chaichana et al, 2009(Chaichana et al, , 2010. The main objectives of our study were to assess the current nutrient status and present environmental conditions across the site, with greater emphasis on three contrasted pools, as exemplars to aid management planning.…”

Section: Introductionmentioning

confidence: 99%

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Conservation of pond systems: a case study of intractability, Brown Moss, UK

2011

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Brown Moss is a Site of Special ScientificInterest in north-west England, of significance because of the occurrence, at least in the past, of the rare plant Luronium natans (Linnaeus) on the one hand, and its public popularity on the other. It is also a part of Ramsar site that comprises several other water bodies, the Meres, collectively valued for their water birds. It includes several fishless pools, in an area of seminatural vegetation, that differ in character. Such features are favoured in pond conservation. The surrounding terrestrial vegetation reflects nutrient enrichment in the past century and the pools at Brown Moss are now hypereutrophic from intensive agriculture on the margins of the site and guanotrophication of the main, central pool. Feral Canada geese (Branta canadensis (Linnaeus)) and resident waterfowl, encouraged by feeding by the public, have had major effects. Lower total phosphorus concentrations but higher nitrate concentrations were found in marginal pools, too small for bird flighting. Sedimentary studies suggest that nutrients and productivity in the pools have increased. Raised phosphorus in sediments was significantly correlated with numbers of sedimentary diatoms. Ponds are potentially of major importance in freshwater conservation in the UK, as they contain a high proportion of the country's freshwater biodiversity, but many have been filled in or severely polluted by farm wastes. Their situation in intensively used agricultural land means that, as in this case study, solution of their problems may often be intractable. The intractability is amplified at Brown Moss by the difficulty of removing aggressive alien species, a common problem in UK pond systems, and by birdfeeding, again a widespread problem particularly in urban ponds. The difficulties at Brown Moss thus typify the problems of pond conservation in the UK and indeed throughout lowland Europe. Current legislation appears impotent to remedy the situation.

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Birds as eutrophicating agents: a nutrient budget for a small lake in a protected area

Cited by 52 publications

References 34 publications

The impact of bird herbivory on macrophytes and the resilience of the clear-water state in shallow lakes: a model study

The impact of bird herbivory on macrophytes and the resilience of the clear-water state in shallow lakes: a model study

Waterfowl Impoundments as Sources of Nitrogen Pollution

Conservation of pond systems: a case study of intractability, Brown Moss, UK

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