Mussel beds are biological power stations on intertidal flats

Satellite remote sensing reveals a positive impact of living oyster reefs on microalgal biofilm development

“…Variations in bathymetry, tidal dynamics, sediment type, irradiance and grazing had already been documented as factors structuring MPB spatio-temporal distribution (Brotas et al, 1995;Méléder et al, 2003;Sahan et al, 2007;Ribeiro et al, 2013). However, to date there are only a few studies which have explicitly investigated the influence of nearby macrobenthic communities on MPB dynamics (Dame, 1993;Méléder et al, 2003Newell, 2004;Engel et al, 2017).…”

“…Oyster reefs are also known to have indirect effects such as modifying the structure of the surrounding sediment and the ambient hydrodynamic conditions, facilitating MPB establishment (Colden et al, 2016). In a recent paper on the impact of mussel beds on MPB biomass development, Engel et al (2017) attributed the positive effect of such beds on MPB biomass to a combination of reduced hydrodynamic stress and increased nutrient availability (and also to potential changes in the associated invertebrate community). In contrast with the observations of Colden et al (2016) and Engel et al (2017), our BACI experiment, in which the oysters were killed while the physical structure of the reef itself was not modified, now allows the pure physical (hydrodynamic) effect to be distinguished from the biological (nutrient enrichment) effect of the oyster reefs, suggesting that the latter process is more important in our study area.…”

“…In a recent paper on the impact of mussel beds on MPB biomass development, Engel et al (2017) attributed the positive effect of such beds on MPB biomass to a combination of reduced hydrodynamic stress and increased nutrient availability (and also to potential changes in the associated invertebrate community). In contrast with the observations of Colden et al (2016) and Engel et al (2017), our BACI experiment, in which the oysters were killed while the physical structure of the reef itself was not modified, now allows the pure physical (hydrodynamic) effect to be distinguished from the biological (nutrient enrichment) effect of the oyster reefs, suggesting that the latter process is more important in our study area. In this respect, the resilience of MPB biomass development around the impacted reef, observed 1 year after the experiment, is probably due to the recolonization of the dead reef by young oysters, following the exceptionally high recruitment which occurred during autumn 2014 (Pouvreau et al, 2015).…”

The use of remote sensing to reveal landscape-scale ecosystem engineering by shellfish reefs

“…Likewise, increased mud concentrations and higher numbers of foraging birds were found in zones around mussel reefs (van der Zee et al 2012). Similarly, mussel reefs were found to boost microphytobenthos biomass over spatially extended scales (Engel et al 2017). The mediation of sedimentation was found to be pronounced on the leeward side of oyster reefs .…”

“…Many benthic organisms rely on the enriched sediment, which is indicated by a higher infaunal biomass and species richness in areas influenced by shellfish reefs (Kröncke 1996). More importantly, the sheltered circumstances in combination with high nutrient (Asmus & Asmus 1991) and light input (Porter et al 2004) close to shellfish reefs is ideal for growth of microphytobenthos (Engel et al 2017).…”