Macroalgae fuels coastal soft-sediment macrofauna: A triple-isotope approach across spatial scales

T I Kahma; A M L Karlson; X Sun; C-M Mörth; C Humborg; A Norkko; I F Rodil

doi:10.1016/j.marenvres.2020.105163

Macroalgae fuels coastal soft-sediment macrofauna: A triple-isotope approach across spatial scales

Mar Environ Res. 2020 Dec:162:105163. doi: 10.1016/j.marenvres.2020.105163. Epub 2020 Oct 5.

Authors

T I Kahma¹, A M L Karlson², X Sun³, C-M Mörth⁴, C Humborg⁵, A Norkko⁶, I F Rodil⁷

Affiliations

¹ University of Helsinki, Tvärminne Zoological Station, J. A. Palménin Tie 260, 10900 Hanko, Finland. Electronic address: ti.kahma@elisanet.fi.
² Stockholm University, Department of Ecology, Environment and Plant Science, 106 91 Stockholm, Sweden; Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden. Electronic address: agnes.karlsson@su.se.
³ Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden. Electronic address: xiaole.sun@su.se.
⁴ Stockholm University, Department of Geological Sciences, 106 91 Stockholm, Sweden. Electronic address: magnus.morth@su.se.
⁵ University of Helsinki, Tvärminne Zoological Station, J. A. Palménin Tie 260, 10900 Hanko, Finland; Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden. Electronic address: christoph.humborg@su.se.
⁶ University of Helsinki, Tvärminne Zoological Station, J. A. Palménin Tie 260, 10900 Hanko, Finland; Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden. Electronic address: alf.norkko@helsinki.fi.
⁷ University of Helsinki, Tvärminne Zoological Station, J. A. Palménin Tie 260, 10900 Hanko, Finland; Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden. Electronic address: ivan.rodil@helsinki.fi.

PMID: 33137597
DOI: 10.1016/j.marenvres.2020.105163

Abstract

Shallow coastal zones may provide cross-habitat nutrient subsidies for benthic communities offshore, as macrophyte matter can drift to deeper sediments. To study the relative importance of carbon and nutrient flows derived from different primary food sources in a coastal ecosystem, the diets of clam Macoma balthica, polychaete Marenzelleria spp. and mussel Mytilus trossulus were examined across environmental gradients in the northern Baltic Sea using a triple-isotope approach (i.e. ¹³C, ¹⁵N and ³⁴S) and Bayesian mixing models (MixSIAR). Our results suggest that in shallow habitats, production from Fucus vesiculosus is the primary energy source for M. balthica. The proportion of macroalgae-derived matter in the diet of M. balthica and Marenzelleria spp. decreased following a depth gradient. Our models for M. trossulus indicate that the pelagic POM dominates its diet. Our results indicate a trophic connectivity between shallow macrophyte-dominated and deeper habitats, which receive significant amounts of nutrient subsidies from shallower areas.

Keywords: Benthic macrofauna; Coastal ecosystem; Food sources; Fucus vesiculosus; Macroalgae; Spatial scale; Stable isotopes.

MeSH terms

Animals
Baltic States
Bayes Theorem
Ecosystem
Food Chain
Nitrogen Isotopes / analysis
Seaweed*

Substances

Nitrogen Isotopes