Drivers of Oyster Reef Ecosystem Metabolism Measured Across Multiple Timescales
- PDF / 2,069,319 Bytes
- 12 Pages / 595.276 x 790.866 pts Page_size
- 50 Downloads / 216 Views
Drivers of Oyster Reef Ecosystem Metabolism Measured Across Multiple Timescales Martin P. Volaric 1 & Peter Berg 1 & Matthew A. Reidenbach 1 Received: 5 August 2019 / Revised: 4 February 2020 / Accepted: 14 April 2020 # Coastal and Estuarine Research Federation 2020
Abstract Oxygen flux measurements between oyster reefs and the overlying water column approximate total ecosystem metabolism, representing a potentially valuable reef monitoring tool. In this study, seasonal oxygen flux measurements were made over an intertidal Crassostrea virginica oyster reef on the Virginia (USA) coast using the non-invasive aquatic eddy covariance (AEC) technique. Reef respiration (R) ranged from − 276 mmol m−2 day−1 in the summer to − 55 mmol m−2 day−1 in the winter, likely due to temperature effects on oyster filtering and sediment microbial activity. Reef gross primary production (GPP) varied less seasonally, resulting in net ecosystem metabolism (NEM) that was highly heterotrophic in the summer (− 141 mmol m−2 day−1) and nearly balanced in the winter (− 11 mmol m−2 day−1). Measurements of reef sediment chl a indicated higher concentrations of benthic microalgae than surrounding bare mudflat, while photosynthesis-irradiance curves utilizing 15-min flux averages confirmed light as a dominant short-term driver of microalgal production. Metabolic values were compared with past AEC results from this reef, creating a 4-year record that included a significant oyster die-off. Over this time span, R was closely coupled to GPP, indicating rapid internal cycling of carbon, while reef primary production was primarily attributed to sediment, rather than epiphytic, microalgae. Both R and GPP substantially decreased following the oyster die-off. These results illustrate that oyster reefs are highly dynamic environments, with complex processes that act on numerous time scales ranging from minutes to years. Consequently, AEC metabolism measurements can aid in oyster reef monitoring. Keywords Crassostrea virginica . Oxygen flux . Benthic microalgae . Primary production
Introduction Oyster reefs are vital coastal systems that provide habitat for a wide range of organisms and improve overall water quality (Coen et al. 2007). Unfortunately, due to a combination of overharvesting (Jackson et al. 2001) and disease (Oliver et al. 1998; Rothschild et al. 1994), oyster populations have declined by 85% globally below nineteenth-century levels (Beck et al. 2011). As a result, oyster reefs have become the focus of many restoration efforts, including successful restorations in both North America and Europe (Beck et al. 2011). Due to their importance to coastal systems, and to the high cost of restoration, oyster reef monitoring techniques have Communicated by Stephen G. Monismith * Martin P. Volaric [email protected] 1
Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA
long been the subject of much research (e.g., Coen and Luckenbach 2000). One attribute of oyster reefs that has recently been studied in more det
Data Loading...
