Sharpe Kristen N, Steinberg Deborah K, Stamieszkin Karen
Virginia Institute of Marine Science, 1375 Greate Rd., Gloucester Point, VA 23062 USA.
Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544 USA.
Estuaries Coast. 2025;48(1):17. doi: 10.1007/s12237-024-01442-8. Epub 2024 Nov 13.
Zooplankton play a key role in the cycling of carbon in aquatic ecosystems, yet their production of carbon-rich fecal pellets, which sink to depth and can fuel benthic community metabolism, is rarely quantified in estuaries. We measured fecal pellet carbon (FPC) production by the whole near-surface mesozooplankton community in the York River sub-estuary of Chesapeake Bay. Zooplankton biomass and taxonomic composition were measured with monthly paired day/night net tows. Live animal experiments were used to quantify FPC production rates of the whole community and dominant individual taxa. Zooplankton biomass increased in surface waters at night (2- to 29-fold) due to diel vertical migration, especially by spp. copepods. Biomass and diversity were seasonally low in the winter and high in the summer and often dominated by copepods. Whole community FPC production rates were higher (3- to 65-fold) at night than during the day, with the 0.5-1 mm size class contributing 2-26% to FPC production in the day versus 40-70% at night. An increase in the relative contribution of larger size fractions to total FPC production occurred at night due to diel vertical migration of larger animals into surface waters. Community FPC production was highest in fall due to increased diversity and abundance of larger animals producing larger fecal pellets, and lowest in summer likely due to top-down control of abundant crustacean taxa by gelatinous predators. This study indicates that zooplankton FPC production in estuaries can surpass that in oceanic systems and suggests that fecal pellet export is important in benthic-pelagic coupling in estuaries.
The online version contains supplementary material available at 10.1007/s12237-024-01442-8.
浮游动物在水生生态系统的碳循环中起着关键作用，然而它们产生的富含碳的粪便颗粒会下沉到深处并为底栖生物群落的新陈代谢提供能量，在河口地区这种情况却很少被量化。我们测量了切萨皮克湾约克河子河口近表层中型浮游动物群落产生的粪便颗粒碳（FPC）。通过每月成对的昼夜拖网测量浮游动物的生物量和分类组成。利用活体动物实验来量化整个群落和优势个体类群的FPC产生率。由于昼夜垂直迁移，夜间表层水域的浮游动物生物量增加（2至29倍），特别是 哲水蚤属的桡足类。冬季生物量和多样性季节性较低，夏季较高，且通常以 哲水蚤属桡足类为主。整个群落的FPC产生率夜间高于白天（3至65倍），0.5 - 1毫米大小级别的个体在白天对FPC产生的贡献为2 - 26%，而夜间为40 - 70%。由于较大个体动物昼夜垂直迁移到表层水域，夜间较大尺寸级别的个体对总FPC产生的相对贡献增加。由于产生较大粪便颗粒的较大动物的多样性和丰度增加，秋季群落FPC产量最高，而夏季最低，可能是由于凝胶状捕食者对丰富的甲壳类类群进行自上而下的控制。这项研究表明，河口浮游动物的FPC产量可能超过海洋系统，并表明粪便颗粒输出在河口的底栖 - 水层耦合中很重要。
在线版本包含可在10.1007/s12237 - 024 - 01442 - 8获取的补充材料。
