EAPSI: The Effect of Sea Temperature and Sediment Load on Respiration and Grazing on Kelp by Sea Urchins

EAPSI：海水温度和沉积物负荷对海胆呼吸和海带放牧的影响

• 批准号: 1713713
• 负责人: Sarah Traiger
• 金额: $ 0.54万
• 依托单位: Traiger Sarah B
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1713713&HistoricalAwards=false
• 关键词: EAPSI; Effect; Sea; Temperature; Sediment

Kelp forests are stands of large seaweeds that provide important ecosystem services, such as providing habitat for fished species, contributing primary productivity to other habitats, and protecting coastal communities from waves and erosion. The persistence of kelp forests depends on the balance between kelp production and consumption by herbivores. Overgrazing by herbivores such as sea urchins can lead to deforestation and loss of kelp forest associated organisms. Ecklonia radiata is the main canopy-forming kelp in northeastern New Zealand and supports fisheries species such as spiny lobster. Sea temperature is predicted to increase over the 21st century both globally and in New Zealand waters. Previous research has shown that rate of food consumption by many marine invertebrates increases at elevated temperature due to increased metabolism. However, the effects of increased temperature on consumption rate may be affected by sedimentation, which is also predicted to change in the future. Sediment load to New Zealand waters has increased due to human activities, and weather changes and coastal erosion are predicted to increase sediment load in the future. This project will investigate the effects of future predicted temperature and sediment load on the grazing and respiration rate of the New Zealand sea urchin (Evechinus chloroticus). Grazing and respiration rates will be measured under current ambient conditions and predicted future elevated temperature and sediment load, separately and in combination, in a lab experiment conducted in collaboration with Dr. Nick Shears at the University of Auckland?s Leigh Marine Laboratory. Understanding the effects of environmental changes on this important member of the kelp forest community will help determine the future stability of kelp forests in New Zealand. Future changes in climate and coastal development could lead to high sediment conditions spreading into locations currently unaffected, with effects on trophic dynamics of those systems. The global stressor of increased sea temperature may interact with local stressors and alter top-down effects in kelp forest systems in ways that cannot be predicted by studying the effects of global or local stressors alone. In areas of low sedimentation, increased temperature could result in increased kelp consumption by urchins and reduced kelp biomass, or even shifts to urchin barrens. High sedimentation may increase urchin energetic costs by reducing grazing efficiency or causing urchins to increase movement. Temperature and sedimentation may have synergist negative effects on urchins, if grazing rates cannot increase to meet metabolic needs in the presence of sediment. This project will investigate the effects of increased temperature and sedimentation, separately and combined, on respiration and grazing rates of E. chloroticus on kelp (Ecklonia radiata) in a factorial lab experiment. The control treatment will be kept at ambient temperature (14°C) and sediment will be added to reflect the low concentrations that currently occur in New Zealand kelp forests (5 mg/cm2). The future temperature treatments will be 2°C above ambient, which is predicted to occur in the 21st century. High sediment treatments will reflect concentrations observed near Auckland where there is currently high terrestrial runoff (35 mg/cm2). The combined effects of temperature and sedimentation on respiration and grazing rates have not previously been tested, but may have critical consequences for trophic dynamics within kelp forests. The interaction between grazers and kelp is fundamental to the persistence of kelp forests, and the results of this experiment will help make predictions about future changes to kelp forests with climate change.This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Royal Society of New Zealand.

海带森林是大型海藻林，提供重要的生态系统服务，如为鱼类物种提供栖息地，为其他栖息地提供初级生产力，并保护沿海社区免受海浪和侵蚀。海带森林的持久性取决于食草动物对海带的生产和消费之间的平衡。海胆等食草动物的过度放牧会导致森林砍伐和与海带森林相关的生物的丧失。辐射藻是新西兰东北部形成树冠的主要海藻，支持带刺龙虾等渔业物种。据预测，21世纪全球和新西兰海域的海温都将上升。先前的研究表明，由于新陈代谢加快，许多海洋无脊椎动物在高温下的食物消耗率会增加。然而，气温升高对消费速度的影响可能会受到泥沙沉积的影响，预计未来也会发生变化。由于人类活动，新西兰水域的泥沙负荷增加，预计天气变化和海岸侵蚀将增加未来的泥沙负荷。本项目将研究未来预测的温度和泥沙负荷对新西兰海胆(Evechinus氯化海胆)放牧和呼吸速率的影响。在与奥克兰大学S海洋实验室的尼克·希尔斯博士合作进行的实验室实验中，将分别测量当前环境条件下的放牧和呼吸速率，并预测未来高温和泥沙负荷。了解环境变化对这一海带森林群落重要成员的影响，将有助于确定新西兰海带森林未来的稳定性。未来气候和沿海开发的变化可能导致高沉积物条件扩散到目前未受影响的地区，从而影响这些系统的营养动态。海温升高的全球压力源可能与局部压力源相互作用，以单靠研究全球或局部压力源的影响无法预测的方式改变海藻森林系统的自上而下效应。在沉降量较低的地区，温度升高可能会导致海胆消耗海带的增加和海带生物量的减少，甚至会转向海胆荒地。高沉积可能会降低海胆的放牧效率或导致海胆增加活动，从而增加海胆的能量成本。如果在有沉积物存在的情况下，放牧率不能增加以满足代谢需要，温度和沉积物可能会对海胆产生协同的负面影响。本项目将在析因实验室实验中，分别和联合研究温度升高和沉积作用对海带上氯化棘豆呼吸作用和摄食率的影响。对照处理将保持在环境温度(14摄氏度)下，并将添加沉积物，以反映新西兰海藻森林目前出现的低浓度(5毫克/平方厘米)。未来的温度处理将比环境高2摄氏度，预计将在21世纪发生。高泥沙处理将反映在奥克兰附近观察到的浓度，那里目前有高陆地径流(35毫克/平方厘米)。温度和沉积物对呼吸和放牧率的综合影响以前没有被测试过，但可能对海带森林中的营养动态产生关键影响。食草动物和海带之间的相互作用是海带森林持续生存的基础，这项实验的结果将有助于预测未来海带森林随着气候变化而发生的变化。该奖项由东亚和太平洋夏季研究所计划设立，支持一名美国研究生的夏季研究，并由NSF和新西兰皇家学会共同资助。