Document Type

Capstone Project

Degree Name

Bachelor of Science (B.S.)


Science & Environmental Policy


aralytic shellfish poisoning toxins (PSPT) pose a serious threat to public health worldwide. Along the west coast of North America, Mytilus californianus (California mussel) has long been used as the primary indicator species for monitoring levels of PSPT in the environment. However, because the distribution of this species is limited to rocky shores, vast stretches of sandy beaches are not monitored for PSPT. This lack of information greatly reduces our ability to track and predict harmful algal bloom development and movement along the west coast of much of North and South America. Early studies on Emerita analoga (sand crab), a common sandy shore invertebrate of the eastern Pacific, showed that this species can sequester saxitoxin (STX, the primary neurotoxin produced by PSPT blooms) in its tissues. The purpose of this study was to develop a PSPT extraction protocol for E. analoga, and to compare the utility of this species as a PSPT indicator with that of M. californianus. Samples of both species were spiked with known amounts of saxitoxin and processed (M. californianus with the standard acid extraction procedure and E. analoga with the new adapted acid extraction process). Spike and recovery results show that E. analoga recovery rates were very similar to those of M. californianus. To compare the accumulation and depuration rates of PSPT for the two species under nearly identical field conditions, samples of each were collected at six pairs of adjacent rocky and sandy beaches along the central coast of California. M. californianus and E. analoga samples collected in 1998 and 1999 from April through November, the season of historically high paralytic shellfish poisoning toxicity, indicate that E. analoga would make an excellent complement to the current PSPT monitoring program. Results from the 2-year study reveal that any PSPT event detected by M. californianus, was also detected by E. analoga. In fact, in one instance, E. analoga detected a spike in HAB activity, that was not reflected by M. californianus. The initial costs to include E. analoga with the regular monitoring regime are minimal, making the use of E. analoga as an bioindicator for PSP toxicity, not only cost efficient, but effective.


Capstone Project (B.S.) Earth Systems Science & Policy Institute

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