Szura Katelyn, McKinney Richard, Wigand Cathleen, Oczkowski Autumn, Hanson Alana, Gurak John, Gárate Melanie
Department of Biological Sciences, University of Rhode Island, 120 Flagg Rd, Kingston, RI 02881, USA.
Atlantic Ecology Division, ORD-NHEERL, U.S. Environmental Protection Agency, 27 Tarzwell Dr., Narragansett, RI 02882, USA.
J Exp Mar Biol Ecol. 2017 Jan;486:282-289. doi: 10.1016/j.jembe.2016.10.029.
New England salt marshes are susceptible to degradation and habitat loss as a result of increased periods of inundation as sea levels rise. Increased inundation may exacerbate marsh degradation that can result from crab burrowing and foraging. Most studies to date have focused on how crab burrowing and foraging can impact the dominant low marsh plant species, . Here we used a mesocosm experiment to examine the relationship of foraging and burrowing activity in two dominant New England crab species, and , and the combined effect of inundation, on the dominant high marsh plant species using a 3 × 2 factorial design with three crab treatments (, control) at two levels of inundation (low, high). Plants were labeled with a nitrogen (N) stable isotope tracer to estimate plant consumption by the two crab species. At both levels of inundation, we found that had a significant negative impact on both above- and below-ground biomass by physically clipping and uprooting the plants, whereas had no significant impact. Low inundation treatments for both crab species had significantly greater aboveground biomass than high inundation. Stable N isotope tracer levels were roughly the same for both and tissue, suggesting that the impact of on was not through consumption of the plants. Overall, our results suggest the potential for to negatively impact marsh stability, and that effects of crab foraging behavior may be heightened by increased inundation.
随着海平面上升，淹没期增加，新英格兰盐沼易受退化和栖息地丧失的影响。淹没期增加可能会加剧因螃蟹挖掘洞穴和觅食而导致的盐沼退化。迄今为止，大多数研究都集中在螃蟹挖掘洞穴和觅食如何影响占主导地位的低沼植物物种上。在这里，我们使用了一个中宇宙实验，采用3×2析因设计，在两种淹没水平（低、高）下设置三种螃蟹处理（有螃蟹、无螃蟹，即对照），来研究新英格兰两种主要螃蟹物种的觅食和挖掘活动之间的关系，以及淹没的综合影响对占主导地位的高沼植物物种的作用。用氮（N）稳定同位素示踪剂标记植物，以估计两种螃蟹对植物的消耗量。在两种淹没水平下，我们发现有螃蟹通过物理剪切和连根拔起植物，对地上和地下生物量都有显著的负面影响，而无螃蟹处理则没有显著影响。两种螃蟹物种的低淹没处理的地上生物量均显著高于高淹没处理。有螃蟹和无螃蟹处理的植物组织中稳定N同位素示踪剂水平大致相同，这表明有螃蟹对植物的影响不是通过消耗植物。总体而言，我们的结果表明有螃蟹可能会对盐沼稳定性产生负面影响，而且螃蟹觅食行为的影响可能会因淹没增加而加剧。
