McCall Donna Drury, Rakocinski Chet F
Department of Coastal Sciences, University of Southern Mississippi-Gulf Coast Research Laboratory, 703 East Beach Drive, Ocean Springs, Mississippi 39564, USA.
Ecology. 2007 Mar;88(3):618-24. doi: 10.1890/06-0375.
Coupled trophic-engineer interactions are potentially important for maintaining habitat function and ecosystem services. As ephemeral submerged aquatic vegetation (SAV), Ruppia maritima has a short well-defined growth-senescence cycle and should benefit from any ecological interaction that enhances its physical condition and longevity. Grass shrimp (Palaemonetes spp.) are abundant facultative grazers of epiphytic algae and conveyors of nutrients in tidal marsh and SAV habitats. Grass shrimp addition consistently enhanced Ruppia biomass and shoot density in a series of three field experiments conducted in Grand Bay National Estuarine Research Reserve, Mississippi, USA. In two experiments, epiphyte grazing by grass shrimp enhanced Ruppia by inhibiting die-back during the mid- and latter stages of the Ruppia life cycle. Despite a nonsignificant epiphyte grazing effect, grass shrimp also enhanced Ruppia during its early growth stage in a third experiment. In that experiment, nutrient addition also significantly increased epiphyte biomass. Grass shrimp may have fostered the early growth of Ruppia through direct deposition of feces to the sediment in the third experiment. Grass shrimp play a pivotal trophic role in the maintenance of Ruppia through context-dependent interactions involving stage of the SAV life cycle, season, and nutrient limitation.
耦合的营养级联工程师相互作用对于维持栖息地功能和生态系统服务可能具有重要意义。作为一种短暂的沉水水生植被，海草（Ruppia maritima）具有明确的短生长 - 衰老周期，应该会从任何增强其身体状况和寿命的生态相互作用中受益。草虾（Palaemonetes spp.）是附生藻类的丰富兼性食草动物，也是潮汐沼泽和沉水水生植被栖息地的营养物质输送者。在美国密西西比州大湾国家河口研究保护区进行的一系列三个野外实验中，添加草虾持续提高了海草的生物量和茎密度。在两个实验中，草虾对附生植物的啃食通过抑制海草生命周期中后期的死亡来促进海草生长。在第三个实验中，尽管草虾对附生植物的啃食效果不显著，但在海草生长早期阶段也促进了海草生长。在该实验中，添加营养物质也显著增加了附生植物生物量。在第三个实验中，草虾可能通过直接向沉积物中排泄粪便促进了海草的早期生长。草虾通过涉及沉水水生植被生命周期阶段、季节和营养限制的背景依赖相互作用，在海草的维持中发挥着关键的营养级作用。
