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New Technology Tracks Algal Toxins

September 15, 2011

Written by Chris Dudenhoeffer, University of California: Santa Cruz Graduate ’10

Original publish date: June 2010.

It’s a crisp and cool morning on the municipal pier in Santa Cruz, California. Monterey Bay is windless and calm, looking more like a bathtub than a vast ocean. Beyond the paint-chipped railing, the water is a murky green. Sunlight penetrates just a few feet through the algae­—the tiny marine plants that motivate my visit today.

Jenny Lane, a doctoral student at the University of California, Santa Cruz, greets me at the end of the wharf. She dons a pair of matching waterproof pants and jacket, and removes two buckets from the back of her trunk. The large white buckets are filled to the brim with clear containers and oddly shaped instruments. We start by collecting and labeling a few samples of water from below the railing. Then, we head to a set of unassuming white stairs halfway down the pier.

A simple wooden platform perches among the pier’s pilings, a few feet above the water. Ropes hang from its railing. Lane begins pulling up the ropes, which are covered by thick, slimy brown algae. Here among the algae is the treasure of this trip. Dangling from brightly colored embroidery hoops are small “teabags” of mesh and resin. These simple white pouches are the latest, cutting-edge tools to track and predict dangerous toxic outbreaks created by tiny ocean organisms.

The algae that produce these dangerous toxins resemble clear needles with dark banding along their length. They’re visible only through a microscope. Though small in size, a few species of algae in the genus Pseudo-nitzschia release the potent neurotoxin, called domoic acid.  The algae may produce domoic acid, when they can’t extract their usual diet of nutrients from the seawater.

In large algal blooms, domoic acid can build up to dangerous levels in coastal waters. It accumulates in shellfish like mussels, which filter water for food.  Eating toxin-saturated mussels can be deadly for both humans and marine organisms. The toxin crosses the blood-brain barrier and attacks the nervous system, deteriorating nerve endings. Symptoms range from vomiting to seizures and short-term memory loss—and even death in the worst cases.

Domoic acid outbreaks can have dramatic effects on local ecosystems. Sea lions, coastal seabirds, and humans can become sick or die from ingesting domoic acid.  Many endangered species, already at low population levels, face threats from harmful algal blooms. In California, the iconic sea otter is a common victim of domoic acid poisoning. Other mammals, such as blue whales and manatees, are prone to poisoning as well.

Harmful algal blooms also can drastically affect local economies. High domoic acid concentrations in the water can force entire fisheries to close, crippling businesses and putting people out of work.  For many coastal communities that depend on fishing, the blooms can spell disaster.

The study of harmful algal blooms is a fledgling field. In 1987 a heavy outbreak of domoic acid in Prince Edward Island, Canada, rattled a community by killing three people and forcing 100 more to the hospital.  Since then more outbreaks have occurred as ocean waters warm, prompting many scientists to examine more closely how and when harmful blooms arise.

Collecting mussels and grinding up their tissue is the most widely used technique to detect and predict marine toxins. Developed by the state, the sentinel mussel watch program uses living mussels to monitor domoic acid levels. However, mussels have several drawbacks. “Using mussels has been described as difficult, expensive, problematic, time consuming, and technically demanding,” says UCSC ocean scientist Raphael Kudela. “It’s not the ideal tool for monitoring algal blooms.”

Kudela and Lane set out to find a simpler way to detect domoic acid in the bay’s waters.  They adapted a new technology, called SPATT.

Short for passive solid phase absorption toxin tracking, SPATT devices look like little resin-filled mesh bags. Filling the fist-sized nylon bags are specialized resin beads, designed to selectively absorb domoic acid from the ocean. Much like steeping a teabag in water, the bags sit in the ocean for a week, soaking up any toxins that drift by.

Conceived and developed 10 years ago in New Zealand, SPATT was originally designed to detect “fat-loving” toxins, which are absorbed and stored in animal fat. Detecting domoic acid, a “water-loving” toxin, was never in SPATT’s design, since such toxins dissolve readily in water. “No one has tried this in the U.S. Everyone we talked to told us it wouldn’t work, but it works beautifully,” says Kudela, chuckling.

Thus far Kudela and Lane’s research reveals that using SPATT has several advantages over using mussels to monitor blooms.  SPATT is simple and cheap, requiring little time or energy to use.  “It’s actually the same price or cheaper than using mussels.  Mussels seem easy and cheap, but SPATT is actually even easier to use. We’re pretty excited about that,” says Kudela. The team recently published in Sea Grant California, with a forthcoming paper in the journal, Limnology and Oceanography: Methods.

SPATT can detect and track toxin levels better than mussels, picking up even tiny levels of the toxin before mussels do. “With this one little bag we can pick up a whole bunch of different toxins, and at levels we normally can’t detect,” says Kudela.  In the 17 months of SPATT’s deployment [as of May 2010], it registered the toxin 3 -7 weeks before the mussels, and 7-8 weeks prior to shellfish toxicity, on average.

Even though SPATT shows clear advantages over the current mussel watch program, the researchers make it clear that SPATT won’t replace mussels. “No one eats SPATT,” Lane says. “If what you care about is shellfish, because you’re eating shellfish, you probably should monitor shellfish.”

To supersede mussels, SPATT would need more scientific validation. Instead, the researchers hope SPATT will provide an early warning system for harmful blooms, giving communities and wildlife agencies valuable time to react as they monitor mussels as well.

Kudela and Lane are now focusing their efforts on expanding SPATT to more piers in and beyond Monterey Bay, and broadening its applications in the field.  “We’re talking with researchers about putting SPATT on the backs of sea lions so we can see where they are getting the toxins. It’s super flexible, much more so than traditional methods,” says Kudela.

Ultimately, Kudela hopes, the technique will reveal algal toxin outbreaks that could grow more frequent as the climate—and the oceans—get warmer. Ideal conditions for larger and longer lasting blooms of harmful algae will keep marine biologists on their toes.

——–

Thanks, Chris for letting me use this!

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