The algal toxin domoic acid (DA) poisons hundreds of marine mammals each year. Presently, first responders do not have access to sensors capable of rapidly and accurately monitoring DA for health assessment, stranding/mortality response, and rehabilitation decisions. We developed a portable hand-held sensor that can measure DA in urine or blood of marine mammals accurately in 15 min., allowing immediate status of exposure to be known. We field tested these sensors and are validating results.
Why We Care
Domoic acid (DA), a harmful algal toxin, is one of the foremost threats to marine animals. It has been identified in birds, pinnipeds (seals, sea lions) and cetaceans (whales, dolphins) in nearly all US coastal waters, with regular and increasing frequency along the west coast in particular. DA is produced by the cosmopolitan diatomPseudo-nitzschia spp. When these toxic algae are consumed by planktivorous fish, the toxin is then capable of entering higher levels of the food web.
Symptoms of DA poisoning include vomiting, aggression, seizures, loss of pregnancy (miscarriage) and death in marine organisms, particularly marine mammals such as the California sea lion (CSL) and dolphins. Affected animals can eventually strand along the shore, either alive or dead, and ‘first responders” (i.e., stranding and rehabilitation coordinators) have little or no immediate information on whether DA poisoning causes these occurrences.
In the past decade NOAA has reported harmful algal blooms (HABs) as the most common cause of marine mammal unusual mortality events (UMEs). Although managers and researchers who coordinate on-site mortality event response efforts are typically experts in marine mammal health, they are generally not equipped to conduct analysis of algal toxins. First responders can now use a portable device to quickly (15 minutes) and accurately measure DA in marine mammals, both in field and clinical settings. The device will immediately reveal the animals’ health status in regards to DA exposure and allow for rapid diagnosis and appropriate treatment.
What We Did
We collaboratively developed a biological sensor, known as a lateral flow device (LFD), with Biosense Laboratories, Ltd to rapidly and accurately measure DA levels in marine mammal urine and blood samples, specifically from dolphins and California sea lions. Production of the LFDs and the hand held readers was funded through an Oceans and Human Health Initiative grant.
We also established a national network of collaborators based on the following three user group profiles:
- health assessment – primarily interested in performing routine health assessments of live, free-ranging marine mammal populations.
- event response – responsible for dispatching personnel to the site of marine mammal strandings to assess the health state of these animals and collect a variety of biological data.
- rehabilitation – admit stranded animals in order to accurately diagnose, treat and release them back into their natural habitat.
We gave nine user groups representing the three profiles 100 LFD tests and a hand held portable reader to quantify DA in blood or urine samples between 10-90 pico-grams (x 10-12) per milliliter (pg/ml). This detection range encompasses values previously seen in samples from CSLs brought to rehabilitation centers for DA poisoning.
What We Found
Through the preliminary inter-laboratory validation study, our collaborators successfully used the LFD and reader to correctly measure the amount of DA present in the laboratory spiked samples. Within one year we collected 174 samples and LFD results from a wide variety of marine mammals, including various whale and seal species in addition to the dolphins and CSLs.
Using the analytical chemical technique liquid chromatography and mass spectrometry (LC/MS), we are analyzing the field samples to confirm the reader results for all samples to determine the accuracy of the LFDs within a wide variety of marine mammal species. To support immediate health assessment, event response and rehabilitation decisions, the LFD sensor, once verified, could become a powerful tool available to stranding and rehabilitation coordinators to monitor DA levels in marine mammals. This work will also advance the objectives of NOAA’s Marine Animal Health and Stranding Response Program and Oceans and Human Health Initiative.