Ill: Periods of hypoxia, dominated by small worms and RPD layter close to the sediment/water interface. Certain groups of species, primarily mollusks and plants, can reduce organic and nutrient loading to the water column (Table 14.3). But physical drivers play a large role in determining the degree of impact to the water column. Suspension-feeders serve to couple pelagic and benthic processes because they filter suspended particles from the water column and the undigested remains, ejected as mucus-bound feces and pseudofeces, sink to the sediment surface.