Microalgae, macrofauna and sediment stability: an experimental test of a reciprocal relationship

Abstract

A manipulative field experiment was conducted at Blackness in the Firth of Forth, Scotland, to study the effects of differences in microphytobenthos abundance on sediment stability and macrofauna. Opaque and transparent Perspex was used to construct shaded and controlled treatments, respectively. Shading resulted in significantly lower levels of chlorophyll a recorded from the sediment. Shaded treatments showed significant reductions in populations of Macoma balthica, Hydrobia ulvae and Corophium volutator, 3 of the dominant species at this site. Largely as a result of changes in the abundance of these species, multivariate analyses showed significant differences between shaded and control communities. The impacts of shading on individual species depended on the sediment characteristics. There were no significant differences between treatments in recorded sediment accretion/erosion rates. These results demonstrate the importance of microphytobenthos for the deposit feeders M. balthica, H. ulvae and C. volutator. The absence of any effect on sediment stability might result from the reciprocal, opposite effects of macrofauna and microphytobenthos on sediment stability cancelling each other out in this experiment.

Impact of biodiversity-climate futures on primary production and metabolism in a model benthic estuarine system

“…The implication of this for temperate estuaries may be quite profound. The overall metabolic balance of estuarine systems between net autotrophy or heterotrophy is under debate [ 28 , 36 ] but the role of autotrophic production by MPB is clear. Reduction of this contribution to the carbon balance will push the system toward a more heterotrophic condition.…”

“…MPB are the main primary producers in many intertidal and shallow subtidal depositional environments [ 33 ], and enhance benthic-pelagic coupling through the formation of biofilms [ 34 , 35 ]. Our hypothesis was that interactions between climate change variables and biodiversity would inhibit autochthonous productivity by MPB [ 36 - 38 ] and hence would affect the net trophic status of these vulnerable coastal systems. This is because CO 2 levels per se do not appear to enhance MPB photosynthesis, while acidification and grazing activity both have a negative influence.…”

Parallel ecological networks in ecosystems

“…(b) The interaction web for the same ecosystem drawn for the detritus production part of consumer-resource interactions, based on measured fluxes as presented by Baird et al (2007). (c) The inferred interaction web for the same ecosystem for other than consumer-resource interactions, drawn for important effects of species on abiotic conditions (ecosystem engineering), response of species to abiotic conditions, external forcing, material inputs and losses, and various physical and chemical interactions, based on information from various sources ( Whitlatch 1981;Flach 1992;Herman et al 1999;Widdows et al 2004;Coco et al 2006;Huxham et al 2006;Lumborg et al 2006). The key interaction in this web is the effect of organisms on physical conditions.…”

Major Changes in the Ecology of the Wadden Sea: Human Impacts, Ecosystem Engineering and Sediment Dynamics

“…These species include seagrasses, biogenic reefs of suspension feeding bivalves and a number of bioturbating polychaete worms and crustaceans, all of which not only respond to sediment stability and texture but also strongly affect it (Reise 1985;Flach 1992;van de Koppel and others 2005a;Huxham andothers 2006, van der Heide andothers 2007). Altering local sediment dynamics by either increasing the erosion of the sediment or promoting the settlement of finer particles causes these species to be a major force on regional landscape-forming processes, interacting with the hydrodynamics imposed upon the system by waves and currents (Bouma and others 2009).…”