Expected and unexpected effects of waterbirds on Mediterranean aquatic plants

Gayet, Guillaume; Croce, Nicolas; Grillas, Patrick; Nourry, Carole; Deschamps, Clémence; Rau, Pierre Defos du

doi:10.1016/j.aquabot.2012.07.002

Cited by 16 publications

(9 citation statements)

References 32 publications

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“…For studies that only reported experiment start dates and observations as a month in a year, we coded the date as the first day of the month and calculated the time elapsed since the experiment began in number of days. Several studies involved either a goose or swan combined with a duck species (e.g., Tubbs and Tubbs, 1983 ; Madsen, 1988 ; Gayet et al, 2012 ) but never a goose and swan together. No study included a duck species exclusively, so for waterfowl species, we further classified whether the study included a goose or a swan species.…”

Section: Methodsmentioning

confidence: 99%

Meta-Analysis of Reciprocal Linkages between Temperate Seagrasses and Waterfowl with Implications for Conservation

et al. 2017

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Multi-trophic conservation and management strategies may be necessary if reciprocal linkages between primary producers and their consumers are strong. While herbivory on aquatic plants is well-studied, direct top-down control of seagrass populations has received comparatively little attention, particularly in temperate regions. Herein, we used qualitative and meta-analytic approaches to assess the scope and consequences of avian (primarily waterfowl) herbivory on temperate seagrasses of the genus Zostera. Meta-analyses revealed widespread evidence of spatio-temporal correlations between Zostera and waterfowl abundances as well as strong top-down effects of grazing on Zostera. We also documented the identity and diversity of avian species reported to consume Zostera and qualitatively assessed their potential to exert top-down control. Our results demonstrate that Zostera and their avian herbivores are ecologically linked and we suggest that bird herbivory may influence the spatial structure, composition, and functioning of the seagrass ecosystem. Therefore, the consequences of avian herbivory should be considered in the management of seagrass populations. Of particular concern are instances of seagrass overgrazing by waterfowl which result in long-term reductions in seagrass biomass or coverage, with subsequent impacts on local populations of waterfowl and other seagrass-affiliated species. While our results showed that bird density and type may affect the magnitude of the top-down effects of avian herbivory, empirical research on the strength, context-dependency, and indirect effects of waterfowl–Zostera interactions remains limited. For example, increased efforts that explicitly measure the effects of different functional groups of birds on seagrass abundance and/or document how climate change-driven shifts in waterfowl migratory patterns impact seagrass phenology and population structure will advance research programs for both ecologists and managers concerned with the joint conservation of both seagrasses and their avian herbivores.

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Section: Methodsmentioning

confidence: 99%

Meta-Analysis of Reciprocal Linkages between Temperate Seagrasses and Waterfowl with Implications for Conservation

et al. 2017

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“…properties. If the grazing activity by swans is conducted through destructive foraging methods that directly affect submerged macrophyte beds, the mechanical disturbance during bottom-feeding activities of flamingoes indirectly affects macrophytes (Gayet et al, 2012;Tatu et al, 2007). Alongside the obvious deleterious effects on aquatic vegetation, large waterbirds also limit the expansion of opportunistic macroalgae, finally resulting in a reduction of the negative effects of eutrophication in lagoons (Gayet et al, 2012).…”

Section: Non-trophic Linkage (Ecosystem Engineers)mentioning

confidence: 99%

Seabird influence on ecological processes in coastal marine ecosystems: An overlooked role? A critical review

Signa

Mazzola

Vizzini

2021

Estuarine, Coastal and Shelf Science

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Seabirds are vital components of coastal ecosystems and connect marine and terrestrial systems at a global scale, significantly contributing to inter-habitat connectivity and the ecological dynamics of the recipient systems. By exhibiting a wide range of ecological functions, seabirds can contribute to shape coastal ecological processes in a multitude of ways, among which directly influencing trophic status, environmental contamination, biodiversity and food webs through trophic (bottom-up or top-down) and non-trophic processes. Although the ecological and functional role of birds in terrestrial areas, islands in particular, has been deeply studied since the last century, the same does not hold true for coastal area. Since coastal areas have a crucial economic and ecological role worldwide and, at the same time, are highly vulnerable, looking into the role of seabirds in influencing the ecosystem functioning in coastal areas is needed nowadays. Here, we review the current knowledge regarding the influence of seabirds on coastal ecological processes highlighting 2 knowledge gaps, with particular emphasis on the avian ecological functions that are crucial in influencing the ecosystem processes and functioning and, therefore, their influence on the provision of ecosystem services and goods for the human well-being.

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“…Simultaneously, the growth rate of aquatic plants in temperate rivers declines after the spring period of growth [12], [22]; thus plants experienced the highest grazing pressures when they were senescing and thus their capacity for compensatory growth was low [12], [22]. This led to substantial reductions in plant abundance as have been reported for other aquatic ecosystems [50], [51], [52]. The positive relationship between swan biomass density and species evenness in the peak-phase, suggested grazing of the more naturally-abundant species [29].…”

Section: Discussionmentioning

confidence: 92%

Understanding Plant Community Responses to Combinations of Biotic and Abiotic Factors in Different Phases of the Plant Growth Cycle

et al. 2012

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Understanding plant community responses to combinations of biotic and abiotic factors is critical for predicting ecosystem response to environmental change. However, studies of plant community regulation have seldom considered how responses to such factors vary with the different phases of the plant growth cycle. To address this deficit we studied an aquatic plant community in an ecosystem subject to gradients in mute swan (Cygnus olor) herbivory, riparian shading, water temperature and distance downstream of the river source. We quantified abundance, species richness, evenness, flowering and dominance in relation to biotic and abiotic factors during the growth-, peak-, and recession-phases of the plant growth cycle. We show that the relative importance of biotic and abiotic factors varied between plant community properties and between different phases of the plant growth cycle. Herbivory became more important during the later phases of peak abundance and recession due to an influx of swans from adjacent pasture fields. Shading by riparian vegetation also had a greater depressing effect on biomass in later seasons, probably due to increased leaf abundance reducing light intensity reaching the aquatic plants. The effect of temperature on community diversity varied between upstream and downstream sites by altering the relative competitiveness of species at these sites. These results highlight the importance of seasonal patterns in the regulation of plant community structure and function by multiple factors.

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Expected and unexpected effects of waterbirds on Mediterranean aquatic plants

Cited by 16 publications

References 32 publications

Meta-Analysis of Reciprocal Linkages between Temperate Seagrasses and Waterfowl with Implications for Conservation

Meta-Analysis of Reciprocal Linkages between Temperate Seagrasses and Waterfowl with Implications for Conservation

Seabird influence on ecological processes in coastal marine ecosystems: An overlooked role? A critical review

Understanding Plant Community Responses to Combinations of Biotic and Abiotic Factors in Different Phases of the Plant Growth Cycle

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