Emerita analoga (Stimpson)--possible new indicator species for the phycotoxin domoic acid in California coastal waters.

Blooms of domoic acid (DA) synthesizing diatoms (Pseudo-nitzschia spp.) have been associated with the death and injury of hundreds of marine shorebirds and mammals, exposed humans to potentially serious health risks, and threatened to significantly impact coastal fisheries and commerce dependent on marine resources. While indicator organisms are widely utilized to monitor for marine biotoxins like paralytic shellfish poisoning toxins, a reliable intertidal indicator species to monitor DA remains to be identified. Here we evaluate and confirm the utility of the common sand crab (Emerita analoga) as an indicator for DA in comparison with sea mussels (Mytilus californianus). Mussels and sand crabs, collected from natural populations in Santa Cruz, California (April 1999-February 2000), were tested for DA using the HPLC-UV method. Toxin loads in sand crabs ranged from below detectable limits to 13.4 micro g DA g(-1) and coincided with the abundance of DA producing Pseudo-nitzschia species nearshore. Toxin levels in mussels collected during the study period were below HPLC-UV detectable limits. The rise and fall of DA in sand crabs in synchrony with Pseudo-nitzschia abundance, combined with this common intertidal species' accessibility and ease of DA extraction, clearly indicate the utility of sand crabs as a reliable, cost-effective monitoring tool for DA in the nearshore coastal environment.

Emerita analoga (Stimpson) as an indicator species for paralytic shellfish poisoning toxicity along the California coast.

Paralytic shellfish poisoning toxins (PSPT) produced by certain harmful algal blooms (HABs) pose a serious threat to public health worldwide. Along the West coast of North America, Mytilus californianus (California sea mussel) has long been used as the primary indicator species for monitoring levels of PSPT in the environment. However, because the natural distribution of this species is limited to rocky shores, vast stretches of coastline bordered by sandy beach habitat are not regularly monitored for PSPT presence. This insufficient spatial coverage greatly reduces the ability to track and predict HAB development and movement along the open coast. Earlier studies on Emerita analoga (common mole or sand crab) demonstrated this species' potential to sequester the neurotoxin saxitoxin (STX) and its derivatives. The goals of this study were to (1) develop a practical and efficient PSPT extraction protocol for sand crabs, and (2) compare the utility and reliability of this species as an indicator of PSPT with that of mussels. Laboratory spike and recovery results showed that STX extraction efficiencies were very similar for both species. Field comparisons of natural accumulation and depuration rates of PSPT for the two species revealed that PSPT events detected using mussels were also identified with sand crabs.