Sunday, June 5, 2011

Brimming Pools: latest Nat Geo issue looks at the vibrant diversity of tidepools

Near neon-like green anemones with tentacles waving in the swirling water; colorful nudibranchs crawling over the substrate; waves of sea grass hiding a myriad collection of shells, crabs, and mollusks. A tropical reef, right? No. A coldwater rocky shoreline? Closer. Try a tidepool.

Or more specifically an intertidal zone along the northern California coast. Due to the movement of ocean currents that churn nutrient-rich waters from deeper depths, certain temperate-zone coastlines benefit from having vibrant and diversified intertidal zones.

National Geographic magazine details the complexity of tidepools in the June issue, on newstands now. "Brimming Pools" is a featured article written by Mel White, with photography by David Liittschwager. White spent time crawling about the rocky shorelines of northern California with marine biologists to learn about the many inhabitants of the intertidal zone and how the zone can be a microcosm of other marine ecosystems and a means to study both sealife growth and the impacts of environmental change - which can be extended to the oceans at large as well.

I had the opportunity to interview the article's author and he touched on some of the issues detailed in the article, from tidepool biodiversity to its precarious future.

RTSea: What attracted you to northern California and the tidepools of Bodega Bay?

MW: My main interest is natural history; recently I’ve covered subjects including Borneo deforestation, crocodiles, and a scientific expedition to New Guinea. I was excited to get the [National Geographic] assignment, because I’ve been fascinated by the intertidal world since I first experienced and wrote about it many years ago at Acadia National Park in Maine.

For various geographic and ecological reasons, the temperate-zone western coasts of continents have the best intertidal life: the western coast of South Africa, the western coast of Chile, and of course the northwestern coast of North America, which harbors some of the most diverse and interesting intertidal life on earth. Since [lead photographer] David Liittschwager is based in San Francisco, and since there’s a long history of research at the Bodega Marine Laboratory, which is in a marine reserve, it was a natural focus for the story.

RTSea: In the National Geographic magazine article, you describe the intertidal zone as “. . . sea grass at the bottom up through strata of sea anemones and mussels and barnacles to the limpets at the top . . .” Do marine biologists define or identify these various strata? And what are the ecological or environmental factors that form or delineate the different strata?

MW: One of the attractions for marine biologists in the intertidal zone is the ability to study life zones and ecological succession in a relatively small area and in a relatively short period of time.

The most obvious factor creating intertidal zonation is the amount of time areas are under water. At the top of the intertidal, organisms may spend only a few minutes each day under water. Even above that is the splash zone, almost never submerged but continually dampened by wave splash, where limpets live. The bottom of the intertidal is exposed to the drying effects of air and direct sunlight less than an hour a day. Then there are countless niches within these zones, such as mini-caves or rock overhangs. The organisms themselves create ecological niches, such as dense sea grass or extensive mussel beds, which are an ecosystem unto themselves. A biologist once pulled up an area of mussel bed less than a square foot, and the number of porcelain crabs and other tiny creatures that scurried away was astounding. Multiply that by many thousands along one stretch of coast and the image is truly awesome.

This ecological stratification promotes diversity. As an example, mussels can out-compete certain barnacles at one level, but just a couple of feet higher the barnacles dominate. A couple of feet lower, the big ochraceous sea stars are a major mussel predator and keep them in check. Certain large snails are important herbivores, but they can live only in sheltered areas because they’re vulnerable to being knocked off the rocks by waves.

RTSea: When thinking of a marine community, most people typically think of coral reefs because of all the various corals, colorful fish, and marine life that live together. But coldwater environments like northern California can be equally diverse, abundant, and colorful. Are these coldwater ecosystems just as fragile as their warm water cousins?

MW: Coldwater systems could be highly vulnerable to changes in ocean temperatures and pH [acidification]—in the former case probably more so than tropical systems.

It’s impossible to spend time studying the coldwater intertidal zone without being continually amazed by the intricate interactions among plants and animals: the symbioses and commensalisms, the camouflage and predator-prey relationships. Nature is resilient, but you understand how quickly the web of life could break down if only a few components are altered or destroyed. And speaking of colorful: There’s nothing on earth more colorful than some of the nudibranchs and even chitons of the northern California coast.

RTSea: With scientists studying the effects of climate change, acidification, pollution and other man-made impacts, have the researchers you spoke with at the Farallon Institute or Bodega Marine laboratory been able to document changes in the local intertidal zones? If so, what are they seeing?

MW: Marine biology is still a relatively new science, and when you combine that with the difficulty of studying many types of marine life, there are a lot more questions than answers, especially when it comes to long-term trends and their significance. Some creatures leave the intertidal zone as larvae and are gone out to sea for weeks or months and nobody know what happens to them or where they go. In only a few places, such as Bodega Bay, have studies been going on long enough to make observations about some of these environmental effects. So right now the attitude is something like cautious observation.

The biologists I talked to were actually more concerned at the moment about certain local anthropogenic influences on intertidal life. Increased runoff from rivers resulting from upstream deforestation can essentially smother nearshore life. The natural-foods movement has meant vastly increased harvesting of certain seaweeds along the northern California coast. One marine biologist has worked with the state to develop seasonal guidelines to try to allow harvest without depleting seaweed populations. Of course, abalones are a key species in nearshore areas, and in places where people can easily access the intertidal zone their populations have dropped and you rarely find large individuals.

RTSea: In the article, you wrote of marine biologist Eric Sanford picking up one rock from a tide pool and finding on it representatives of “more than one-fourth of all animal life on Earth.” Do you think that people are beginning to realize more and more, the vital life connection between the seas and our own future existence? What do you think ocean conservationists need to do more of to reach people, getting more people to support ocean conservation?

MW: As a pessimist, I’m afraid too many people are more interested in the latest pop song or having a fancy cell phone than in trying to understand complicated environmental issues. The BP oil disaster in the Gulf of Mexico held people’s interest for a while, and it’s probably a sad but true fact of human nature that we don’t pay attention until something slaps us in the face: no shrimp in the grocery store, favorite beaches closed, marine-dependent jobs lost. I suppose it helps when celebrities such as Ted Danson and Sigourney Weaver speak out on environmental issues, but I’m depressed that educational budget cutbacks mean less time for non-core subjects such as environmental studies.

On the other hand, Facebook and similar Internet networks allow people to communicate and organize quickly around issues, which offers hope for effective activism. On the other other hand, conservationists are still going up against the huge budgets and political power of oil companies, automakers, and business interests, which care more about the next quarter’s profits than the long-term health of the planet. There’s absolutely no reason why vehicles in the United States shouldn’t be averaging well over 30 miles per gallon, which would eliminate the need for more ocean oil drilling—except that politicians beholden to oil and car companies keep vetoing higher fuel-economy standards.

I’d like to think that the general trend in human consciousness is toward a better understanding of environmental issues, and I think that’s probably true. Can that overcome basic human inertia and short-term selfishness in time to avoid catastrophe? I send my money to environmental organizations and I encourage my friends to do the same.

As the June issue of National Geographic once again shows, there is something very special about stunning photographs, beautifully printed, with informative text - it's a tactile experience that, in this digital world, I still cannot shake. That's why I have been a subscriber to the magazine since 1976.

Take a look at the "Brimming Pools" in the June, 2011 issue of National Geographic, on newstands now.

Click here to view the photography of David Liittschwager.
Click here to watch a time-lapse video of changing tides covering tidepools.

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