Bird traits and their nutrient impact on terrestrial invertebrate populations

Vegt, Wim Van der; Bokhorst, Stef

doi:10.1007/s00300-023-03161-5

Cited by 4 publications

(2 citation statements)

References 90 publications

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“…These links have highlighted the major role seabird subsidies play in atoll biodiversity (Benkwitt et al, 2020;Lorrain et al, 2017) and ecosystem services (Plazas-Jiménez & Cianciaruso, 2020), and hence the need to better understand seabird contributions to atoll terrestrial and marine ecosystems (Berr et al, 2023). Despite this importance, studies of seabird effects on atolls remain limited and are often underrepresented in global meta-analyses (Grant et al, 2022;Van Der Vegt & Bokhorst, 2023).…”

Section: Introductionmentioning

confidence: 99%

Seabird presence and seasonality influence nutrient dynamics of atoll habitats

Appoo,

Bunbury,

Letori

et al. 2024

Biotropica

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Marine nutrients underpin productivity and functioning of oceanic island ecosystems. On islands where they nest, seabirds represent a primary source of marine nutrients. In tropical regions, some of the largest seabird populations nest on atolls, yet there is limited information available on seabird contributions to atoll ecosystem nutrient dynamics. To investigate the spatial and seasonal dynamics of seabird contributions, we assessed seabird colonies of different taxa, including red‐footed boobies and terns, nesting on separate islands of Farquhar Atoll, Seychelles. We assessed nutrient concentrations of guano, soil, coastal plants, and nearby seagrass in seabird colonies and at a control island with no seabirds, during the wet and dry seasons. Sooty terns contributed the highest quantities of nutrients, estimated at 71.2 N tonne/year and 52.2 P tonne/year. Seabird‐derived nutrient transfer occurred year‐round from seabird colonies to soil, coastal plants and seagrass. Soil macro‐ and inorganic nutrients were higher in the high‐density tern colony and during the dry season, coinciding with the breeding period of sooty terns. Both red‐footed booby and tern colonies maintained high nitrogen levels in coastal plants year‐round, while phosphorus levels did not differ between islands or seasons. Seabird‐derived nitrogen reversed nitrogen limitation of seagrass during the dry season. We provide the first insights into seabird nutrient contributions to atoll ecosystems in Seychelles, with recommendations for seabird conservation to boost and support atoll and island ecosystem resilience. Our results from a relatively undisturbed atoll serve as a baseline with which more impacted atolls and future changes can be assessed.

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Section: Introductionmentioning

confidence: 99%

Seabird presence and seasonality influence nutrient dynamics of atoll habitats

Appoo,

Bunbury,

Letori

et al. 2024

Biotropica

View full text Add to dashboard Cite

show abstract

“…These links have highlighted the major role seabird subsidies play in atoll biodiversity (Lorrain et al, 2017; Benkwitt et al, 2020) and ecosystem services (Plazas-Jiménez & Cianciaruso, 2020), and hence the need to better understand seabird contributions to atoll terrestrial and marine ecosystems (Berr et al, 2023). Despite this importance, studies of seabird effects on atolls remain limited and are often underrepresented in global meta-analyses (Grant et al, 2022; Van Der Vegt & Bokhorst, 2023).…”

Section: Introductionmentioning

confidence: 99%

Seabird traits and seasonality modulate nutrient dynamics of terrestrial and marine habitats on atolls

Appoo,

Bunbury,

Letori

et al. 2023

Preprint

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Marine nutrients underpin productivity and functioning of oceanic island ecosystems. Seabirds represent a primary source of marine nutrients. In tropical regions, some of the largest seabird populations nest on atolls, yet there is limited information available on seabird contributions to atoll ecosystem nutrient dynamics. To investigate the spatial and seasonal dynamics of seabird contributions, we assessed seabird colonies of different taxa, including red-footed boobies and terns, nesting on separate islands of Farquhar Atoll, Seychelles. We assessed nutrient concentrations of guano, soil, coastal plants and nearby seagrass in seabird colonies and at a control island with no seabirds, during the wet and dry seasons. Sooty terns contributed the highest quantities of nutrients, estimated at 71.2 N tonne.yr-1and 52.2 P tonne.yr-1. Seabird-derived nutrient transfer occurred year-round from seabird colonies to soil, coastal plants and seagrass. Soil macro- and inorganic nutrients were higher in the high-density, ground-nesting tern colony and during the dry season, coinciding with the breeding period of sooty terns. Both red-footed booby and tern colonies maintained high nitrogen levels (%N) in coastal plants year-round, while phosphorus levels (%P) did not differ between islands or seasons. Seabird-derived nitrogen reversed nitrogen limitation (log C:N) of seagrass during the dry season. We provide the first insights into seabird nutrient contributions to atoll ecosystems in Seychelles, with recommendations for seabird conservation to boost and support atoll and island ecosystem resilience. Our results from a relatively undisturbed atoll serve as a baseline with which more impacted atolls and future changes can be assessed.

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Migratory-derived resources induce elongated food chains through middle-up food web effects

Moccetti,

Sperlich,

Saboret

et al. 2024

Mov Ecol

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Background Seasonal movements of animals often result in the transfer of large amounts of energy and nutrients across ecosystem boundaries, which may have large consequences on local food webs through various pathways. While this is known for both terrestrial- and aquatic organisms, quantitative estimates on its effects on food web structure and identification of key pathways are scarce, due to the difficulty in obtaining replication on ecosystem level with negative control, i.e. comparable systems without migration. Methods In this study, we estimate the impact of Arctic charr (Salvelinus alpinus) migration on riverine ecosystem structure, by comparing multiple streams with strictly resident populations above natural migration barriers with streams below those barriers harboring partially migratory populations. We compared density estimates and size structure between above and below populations. Diet differences were examined through the analysis of stomach contents, changes in trophic position were examined by using stable isotopes. To infer growth rate of resident individuals, back-growth calculation was performed using otoliths. Results We find higher densities of small juveniles in partially migratory populations, where juvenile Arctic charr show initially lower growth, likely due to higher intraspecific competition. After reaching a size, where they can start feeding on eggs and smaller juveniles, which are both more frequent in partially migratory populations, growth surpasses that of resident populations. Cannibalism induced by high juvenile densities occurred almost exclusively in populations with migration and represents an altered energy pathway to the food web. The presence of large cannibalistic charr feeding on smaller ones that have a similar trophic level as charr from strictly resident populations (based on stomach content) coupled with steeper δ15N-size regression slopes illustrate the general increase of food chain length in systems with migration. Conclusions Our results thus suggest that the consumption of migration-derived resources may result in longer food chains through middle-up rather than bottom-up effects. Furthermore, by occupying the apex of the food chain and feeding on juvenile conspecifics, resident individuals experience reduced competition with their young counterparts, which potentially balances their fitness with migratory individuals.

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Bird traits and their nutrient impact on terrestrial invertebrate populations

Cited by 4 publications

References 90 publications

Seabird presence and seasonality influence nutrient dynamics of atoll habitats

Seabird presence and seasonality influence nutrient dynamics of atoll habitats

Seabird traits and seasonality modulate nutrient dynamics of terrestrial and marine habitats on atolls

Migratory-derived resources induce elongated food chains through middle-up food web effects

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