RUI: Influence of Harmful Algal Blooms on the Distribution and Ecology of High Level Marine Predators

将在两个地理区域(加利福尼亚州和阿拉斯加)对高级海洋捕食者(海獭和滨鸟)在自然条件下的觅食行为和分布进行测试，这一假设是由有害藻华(HAB‘s)引起的底栖猎物毒性所调节的。由于底栖动物群落结构通常通过捕食自上而下地控制，如果关键捕食者避开整个区域或经常暴露在有毒水华中的猎物种群，这些栖息地中的植物毒素的影响将进一步放大。在阿拉斯加东南部，假设海獭的觅食受麻痹性贝毒毒素(PSPT)分布的调控，这一假设将得到检验，方法是确定：1)阿拉斯加东南部不断扩大的海獭种群是否占据了那些盛产黄油蛤壳但常年含有显著生物学意义的PSPT水平的通道地点，以及2)如果是，海獭是否已经改变了它们的饮食习惯，从主要的捕食者转向无毒的替代贝类毒素(PSPT)，或者继续吃黄油蛤壳，但可能同时丢弃了最有毒的身体部位。第二个研究部分将侧重于加利福尼亚州北部三种常见的岸鸟(戈德威斯、杜威、捕牡蛎)对两种主要潮间带无脊椎动物猎物(鼹蟹和贻贝)PSPT含量可预见的季节性增加的反应。通过监测无脊椎动物猎物毒性水平的季节性变化与鸟类在加州海岸几个相隔很远的地点的觅食行为和分布的变化，将检验这些鸟类捕食者的觅食策略也由PSPT介导的一般假设。

The general hypothesis that the foraging behavior and distribution of high level marine predators (sea otters and shorebirds) under natural conditions are mediated by benthic prey toxicity due to harmful algal blooms (HAB's) will be tested in two geographic regions regions (California and Alaska). Because benthic community structure is often controlled from the top down via predation, the influence of phytotoxins in these habitats will be further amplified if key predators avoid entire regions or prey populations regularly exposed to toxic blooms. In southeast Alaska, the general hypothesis that sea otter foraging is regulated by paralytic shellfish poisoning toxins (PSPT) distribution will be tested by determining: 1) whether or not the expanding southeast Alaskan sea otter population has occupied inside passage sites where butter clams are abundant but contain biologically significant levels of PSPT year round, and 2) if so, whether the sea otters have either shifted their diet away from their primary butter clam prey to alternate non toxic species, or are continuing to eat butter clams, but perhaps while discarding the most toxic body parts. The second research component will focus on the response of three common northern California shore birds (Godwits, Dowitchers, Oystercatchers) to the predictable seasonal increase in the PSPT content of two major intertidal invertebrate prey (mole crabs and mussels). The general hypothesis that the foraging strategies of these avian predators is also mediated by PSPT will be tested by monitoring and correlating seasonal changes in invertebrate prey toxicity levels with changes in the foraging behavior and distribution of the birds at several widely separated sites along the California coast.