Dirk de Beer

Permeable sandy sediments cover at least half of the continental margins and are highly biogeochemically active because of their permeability. Due to the efficient sediment–water exchange of organics and electron acceptors, the mineralization processes occur at much higher rates than in silts or clays (Boudreau et al. 2001; Huettel et al. 2014).

1 Introduction Reef building, scleractinic corals construct a complex three dimensional (3D) calcium carbonate skeleton, which is the framework for coral reef ecosystems of considerable biological and socio-economic importance (Costanza et al., 2014).

Abstract Photogranules are spherical aggregates formed of complex phototrophic ecosystems with potential for “aeration-free” wastewater treatment. Photogranules from a sequencing batch reactor were investigated by fluorescence microscopy, 16S/18S rRNA gene amplicon sequencing, microsensors, and stable- and radioisotope incubations to determine the granules’ composition, nutrient distribution, and light, carbon, and nitrogen budgets.