University of Maryland Center for Environmental Science, Horn Point Laboratory, Cambridge, Maryland, United States of America.
Virginia Institute of Marine Science, College of William & Mary, Gloucester Point, Virginia, United States of America.
PLoS One. 2018 Dec 26;13(12):e0209799. doi: 10.1371/journal.pone.0209799. eCollection 2018.
Oyster reef restoration can significantly increase benthic denitrification rates. Methods applied to measure nutrient fluxes and denitrification from oyster reefs in previous studies include incubations of sediment cores collected adjacent to oyster clumps, benthic chambers filled with intact reef segments that have undergone in situ equilibration and ex situ incubation, and cores with single oysters. However, fluxes of nutrients vary by orders of magnitude among oyster reefs and methods. This study compares two methods of measuring nutrient and metabolic fluxes on restored oyster reefs: incubations including intact segments of oyster reef and incubations containing oyster clumps without underlying sediments. Fluxes of oxygen (O2), dissolved inorganic carbon (DIC), ammonium (NH4+), combined nitrate and nitrite (NO2/3-), di-nitrogen (N2), and soluble reactive phosphorus (SRP) were determined in June and August in Harris Creek, a tributary of the Chesapeake Bay, Maryland, USA. Regression of fluxes measured from clumps alone against those measured from intact reef segments showed significant positive relationships for O2, DIC, NH4+, and SRP (R2 = 0.920, 0.61, 0.26, and 0.52, respectively). Regression of clump fluxes against the oyster tissue biomass indicates significant positive relationships for O2 and NH4+, marginally significant and positive relationships for DIC and N2, and no significant relationship for NO2/3- or SRP. Although these results demonstrate that the incubation of oyster clumps without underlying sediments does not accurately represent biogeochemical fluxes measured from the whole oyster and sediment community, this work supports the need to understand the balance between the metabolism of oysters and local sediments to correctly estimate biogeochemical rates.
牡蛎礁恢复可以显著提高底栖脱氮速率。以前的研究中，用于测量牡蛎礁营养通量和脱氮的方法包括：采集牡蛎丛附近的沉积物芯进行培养；用经过原位平衡和体外培养的完整珊瑚礁段填充底栖室；以及用单个牡蛎填充的芯。然而，牡蛎礁和方法之间的营养通量差异很大。本研究比较了两种测量恢复牡蛎礁营养和代谢通量的方法：包括完整的牡蛎礁段的培养和不包含底泥的牡蛎丛的培养。2019 年 6 月和 8 月，在美国马里兰州切萨皮克湾的哈里斯溪（Harris Creek），测定了氧（O2）、溶解无机碳（DIC）、铵（NH4+）、硝酸盐和亚硝酸盐（NO2/3-）、二氮（N2）和可溶性活性磷（SRP）的通量。仅从丛集测量的通量与从完整珊瑚礁段测量的通量的回归表明，O2、DIC、NH4+和 SRP 呈显著正相关（R2 分别为 0.920、0.61、0.26 和 0.52）。丛集通量与牡蛎组织生物量的回归表明，O2 和 NH4+呈显著正相关，DIC 和 N2 呈边际显著正相关，NO2/3-和 SRP 则无显著相关性。尽管这些结果表明，没有底泥的牡蛎丛集的培养并不能准确代表从整个牡蛎和沉积物群落测量到的生物地球化学通量，但这项工作支持了需要了解牡蛎和当地沉积物代谢之间的平衡，以正确估计生物地球化学速率。
