Virginia Institute of Marine Science
Hypoxia in Chesapeake Bay has substantially increased in recent decades, with detrimental effects on macrobenthic production; the production of these fauna link energy transfer from primary consumers to epibenthic and demersal predators. As such, the development of accurate predictive models that determine the impact of hypoxia on macrobenthic production is important. A continuous-time, biomass-based model was developed for the lower Rappahannock River, a Bay tributary prone to seasonal hypoxia. Phytoplankton, zooplankton, and macrobenthic state variables were modeled, with a focus on quantitatively constraining the effect of hypoxia on macrobenthic biomass. This was accomplished through regression with Z': a sigmoidal function between macrobenthic biomass and dissolved oxygen concentration, derived using macrobenthic data collected from the Rappahannock River during the summers of 2007 and 2008, and applied to compute hypoxia-induced mortality as a rate process. The model was verified using independent monitoring data collected by the Chesapeake Bay Program. Simulations showed that macrobenthic biomass was strongly linked to dissolved oxygen concentrations, with fluctuations in biomass related to the duration and severity of hypoxia. Our model demonstrated that hypoxia negatively affected macrobenthic biomass, as longer durations of hypoxia and greater hypoxic severity resulted in an increasing loss in biomass. This exercise represents an important contribution to modeling anthropogenically impacted coastal ecosystems, by providing an empirically constrained relationship between hypoxia and macrobenthic biomass, and applying that empirical relationship in a mechanistic model to quantify the effect of the severity, duration, and frequency of hypoxia on benthic biomass dynamics.
CLAM MACOMA-BALTHICA; BEHAVIORAL-RESPONSES; BENTHIC MACROFAUNA; OXYGEN DEPLETION; DISSOLVED-OXYGEN; EUTROPHICATION; POLYCHAETE; DYNAMICS; WATER; POPULATION
Virginia DEQ funded the benthic monitoring program in the lower Bay. Support for this work was provided by National Oceanic and Atmospheric Administration grant NA05NOS4781202, a National Science Foundation funded Hall-Bonner Fellowship, and a National Oceanic and Atmospheric Administration Graduate Sciences Program fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding received for this study.
Sturdivant SK, Brush MJ, Diaz RJ (2013) Modeling the Effect of Hypoxia on Macrobenthos Production in the Lower Rappahannock River, Chesapeake Bay, USA. PLoS ONE 8(12): e84140. doi:10.1371/journal.pone.0084140