| 1. |
- Mäkelin, Saara, et al.
(author)
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Linking Resource Quality and Biodiversity to Benthic Ecosystem Functions Across a Land-to-Sea Gradient
- 2024
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In: Ecosystems. - 1432-9840 .- 1435-0629. ; 27:2, s. 329-345
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Journal article (peer-reviewed)abstract
- Benthic macrofauna modifies carbon and nutrient retention and recycling processes in coastal habitats. However, the contribution of benthic consumers to carbon and nutrient storage and recycling shows variation over spatial scales, as the benthic community composition changes in response to differences in environmental conditions. By sampling both shallow sandy and deep muddy sediments across a land-to-sea gradient in the northern Baltic Sea, we explored if benthic community composition, stoichiometry and process rates change in response to alterations in environmental conditions and food sources. Our results show that benthic faunal biomass, C, N, and P stocks, respiration rate and secondary production increase across the land-to-sea gradient in response to higher resource quality towards the open sea. The seston δ13C indicated terrestrial runoff and δ15N sewage input at the innermost study sites, whereas more fresh marine organic matter towards the open sea boosted benthic faunal carbon storage, respiration rate, and secondary production, that is, the generation of consumer biomass, which are essential processes for carbon turnover in this coastal ecosystem. Also, biological factors such as increasing species richness and decreasing biomass dominance of the clam Macoma balthica were significant in predicting benthic faunal C, N, and P stocks and process rates, especially at sandy sites. Interestingly, despite the variation in food sources, the benthic faunal C:N:P ratios remained stable across the gradient. Our results prove that human activities in the coastal area can influence the important links between biodiversity, structure, and process rates of benthic communities by modifying the balance of available resources, therefore hampering the functioning of coastal ecosystems.
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| 2. |
- Rodil, Iván F., et al.
(author)
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Estimating Respiration Rates and Secondary Production of Macrobenthic Communities Across Coastal Habitats with Contrasting Structural Biodiversity
- 2020
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In: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 23:3, s. 630-647
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Journal article (peer-reviewed)abstract
- A central goal of benthic ecology is to describe the pathways and quantities of energy and material flow in seafloor communities over different spatial and temporal scales. We examined the relative macrobenthic contribution to the seafloor metabolism by estimating respiration and secondary production based on seasonal measurements of macrofauna biomass across key coastal habitats of the Baltic Sea archipelago. Then, we compared the macrofauna estimates with estimates of overall seafloor gross primary production and respiration obtained from the same habitats using the aquatic eddy covariance technique. Estimates of macrobenthic respiration rates suggest habitat-specific macrofauna contribution (%) to the overall seafloor respiration ranked as follows: blue mussel reef (44.5) > seagrass meadow (25.6) > mixed meadow (24.1) > bare sand (17.8) > Fucus-bed (11.1). In terms of secondary production (g C m(-2) y(-1)), our estimates suggest ranking of habitat value as follows: blue mussel reef (493.4) > seagrass meadow (278.5) > Fucus-bed (102.2) > mixed meadow (94.2) > bare sand (52.1). Our results suggest that approximately 12 and 10% of the overall soft-sediment metabolism translated into macrofauna respiration and secondary production, respectively. The hard-bottoms exemplified two end-points of the coastal metabolism, with the Fucus-bed as a high producer and active exporter of organic C (that is, net autotrophy), and the mussel reef as a high consumer and active recycler of organic C (that is, net heterotrophy). Using a combination of metrics of ecosystem functioning, such as respiration rates and secondary production, in combination with direct habitat-scale measurements of O-2 fluxes, our study provides a quantitative assessment of the role of macrofauna for ecosystem functioning across heterogeneous coastal seascapes.
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| 3. |
- Rodil, Iván F., et al.
(author)
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Sandy Beaches as Biogeochemical Hotspots : The Metabolic Role of Macroalgal Wrack on Low-productive Shores
- 2019
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In: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 22:1, s. 49-63
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Journal article (peer-reviewed)abstract
- Sandy beaches, which represent the most common type of land-sea interface, harbor distinctive biotic communities and regulate the flow of energy between marine and terrestrial ecosystems. Accumulations of sea wrack on sandy beaches are of crucial importance for recycling beach nutrients and for regulating trophic connectivity and coastal functioning. We investigated the role of beaches as biogeochemical hotspots by examining the metabolic activity in accumulations of different species of wrack on two exposed beaches affected by different levels of human pressure. Experimental wrack patches provided large amounts of different sedimentary nutrients over time due to remineralization of the algae. Unsurprisingly, the variation in the nutrients present in the beach sediments was related to the species of wrack considered. Macroalgal wrack was metabolically very active and supported high respiration rates represented by intense CO2 fluxes. Importantly, we demonstrated that the wrack metabolic rate differed significantly depending on the algal species considered. Different macrofauna and bacterial assemblages were identified in the different wrack patches and on the different beaches. We suggest that human activities such as beach grooming can modify the wrack-associated communities, thus contributing to the variability in the biogeochemical processes and metabolic rates. Significant changes in the type and amount of wrack deposited on beaches can change fundamental processes related to the marine-terrestrial transfer of nutrients and energy and to the marine-atmospheric transfer of CO2 emissions, with ecological consequences for nearshore environments.
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