Influence of New Zealand cockles (Austrovenus stutchburyi) on primary productivity in sandflat-seagrass (Zostera muelleri) ecotones
Number of Authors: 7
2016 (English)In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 181, 238-248 p.Article in journal (Refereed) Published
New Zealand cockles (Austrovenus stutchburyi) are ecologically important, intertidal bivalves that have been shown to influence nutrient cycles and the productivity of microphytobenthos on sandflats. Here, we investigated the potential for cockles to impact the productivity of seagrass, Zostera muelleri, and examined interactions between these habitat-defining species where they co-occur. We sampled bivalve densities and sizes, sediment properties, and seagrass shoot densities across the boundaries of two seagrass patches on an intertidal sandflat in northern New Zealand, and measured dissolved oxygen and nutrient fluxes in light and dark benthic incubation chambers in conjunction with a 0-97% gradient in seagrass cover. Although gross primary production (GPP, mu mol O-2 m(-2) h(-1)) increased predictably with the cover of live seagrass, the density of cockles and sediment properties also contributed directly and indirectly. Seagrass cover was positively correlated with cockle density (ranging from 225 to 1350 individuals per m(2)), sediment mud percentage (0.5-9.5%), and organic matter content (0.5-2.2%), all of which can affect the efflux of ammonium (readily utilisable inorganic nitrogen) from sediments. Moreover, the cover of green seagrass blades plateaued (never exceeded 70%) in the areas of highest total seagrass cover, adding complexity to cockle-seagrass interactions and contributing to a unimodal cockleGPP relationship.
Place, publisher, year, edition, pages
2016. Vol. 181, 238-248 p.
Bivalves, Gross primary production (GPP), Intertidal, Macrofauna, Nutrient flux, Species interactions
Biological Sciences Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:su:diva-136263DOI: 10.1016/j.ecss.2016.08.045ISI: 000386406500023OAI: oai:DiVA.org:su-136263DiVA: diva2:1052350