Sea-bed Mixing and Particle Residence Times in Biologically and Physically Dominated Estuarine Systems: a Comparison of Lower Chesapeake Bay and the York River Subestuary

Dead in the water: The fate of copepod carcasses in the York River estuary, Virginia

“…Assuming a settling velocity of , 0.1 cm s 21 (Table 3) and an average channel depth of , 10 m (Dellapenna et al 1998), copepodite carcasses could sink out of the York River water column in under 3 h. However, several lines of evidence indicate that most carcasses remain in the water column for much longer as a result of turbulent mixing: (1) Tang et al (2006a) observed that an average 29% of collected copepods were carcasses in the York River during summer 2005. In the absence of resuspension and upward turbulent diffusion, the high carcass abundance and high settling velocity translate to an extremely high post-hatch mortality rate of ca.…”

Sediment mixed layer as a proxy for benthic ecosystem process and function

“…seasonal, Green et al 2004) and site-specific and can be influenced by physical mixing (e.g. Yingst & Aller 1982, Dellapenna et al 1998, making it fundamentally different from tracer derived mixing depths. Attempts to relate the MD I directly to benthic community measures alone are therefore unlikely to be satisfactory, even when patterns are highly correlated.…”

“…Although it is widely accepted that biological communities influence the depth of the mixed layer (Pearson & Rosenberg 1978), it has been argued that the mixing depth can primarily reflect physical disturbance (e.g. in intertidal/estuarine areas, Dellapenna et al 1998; in deep areas, Yingst & Aller 1982, Diaz 2004) and environmental factors (e.g. oxygen depletion, Nilsson & Rosenberg 1997; organic enrichment, Pearson & Rosenberg 1978, Valente et al 1992, including the supply and availability of food, rather than the activity of benthic infauna per se (Boudreau 1998, Smith & Rabouille 2002.…”

“…where the distribution of tracers is homogenised, e.g. Dellapenna et al 1998), or the maximum depth of mixing (= maximum tracer penetration, e.g. Smith & Rabouille 2002) to ensure that conveyor processing and/or extended deep galleries (e.g.…”

The origin and preservation of a major hurricane event bed in the northern Gulf of Mexico: Hurricane Camille, 1969

“…Numerous macrobenthos that were observed dur-ing core subsampling are also indicative of bioturbation. Mixing processes, whether physical (Dellapenna et al, 1998) or biological (e.g. Benninger et al, 1979), tend to homogenize particlebound radioisotopes as well as sediment, resulting in a reduced gradient of radioisotope activity with depth.…”