Dive Dry with Dr. Bill

106: Shifting Baselines

"Hey, did you get a chance to buy stock in Catalina Underwater Technologies Inc. Enterprises (CUTIE) last week? It was selling for $45, up from the $15 I bought it at two months ago. I tripled my money!" "No, I bought the stock two years ago when it peaked at $95, so I've lost $50 per share." If you're like me, you resemble the latter more than the former. But what has investing in stocks to do with marine biology, pray tell, Dr. Bill? The importance of this hypothetical exchange is that in evaluating the current status of a stock, it is important to know what your baseline was. I'm referring to the value of the stock when you bought it.

The same is true in evaluating the health of ecological systems. For the most part we have little or no direct measures of what our marine (or terrestrial) ecosystems were like before human beings began interacting with them. Aboriginal humans entered these systems tens of thousands of years ago and impacted them well before "ecology" entered the English vocabulary. For that matter, well before English had become a language! While we like to adopt the myth that aboriginal tribes were in harmony with their environment, there is plenty of evidence to the contrary even here on Catalina. There just weren't as many of them and the technology was still in the Stone Age. Europeans appeared a few centuries ago. Rapid technological change and the exponential increase in our state's population have greatly accelerated the rate at which humans impact our ecosystems today.

For these reasons, it is difficult to establish a "fixed" baseline to measure the health of any ecosystem. Of course such systems were subjected to non-human changes such as the Ice Ages and dry periods, but these tended to happen on longer time scales. Of course short-term events like large storms and El Ninos are an exception to this. But the important point is that no real scientific ecological studies were undertaken in 20,000 BP when aboriginal populations began increasing, or in 1800 to give us some baseline as aboriginal cultures were largely replaced by European settlement.

Think of the changes in Catalina's marine environment since European settlement. The sea otter, a dominant and ravenous predator and a major player ("keystone species") in our kelp forests, was on its way to local extinction in the Channel Islands, hunted for its rich fur valued by Chinese nobles. As the otter population dwindled, the species they would normally eat were released from some predator pressure. In our waters abalone, sea urchins and other otter delicacies undoubtedly increased significantly with one primary predator removed from the food web.

As the urchin populations increased, undoubtedly species like the sheephead which feed on them also grew. California fishermen liked the taste of sheephead and this species was soon heavily impacted by fishing activities. Now in areas depleted of sheephead, we see urchin barrens where kelp is largely prevented from growing back. Fortunately this is not the case in the Casino Point Dive Park where we have healthy sheephead and kelp populations, and no problem with urchins.

Then in the mid-1800's, Chinese immigrants began fishing for abalone which were not considered a food source by early Europeans. Anti-Chinese sentiment in the state led to banning of shallow water (< 20 ft.) abalone fishing in 1900. Japanese-American divers began harvesting abalone from deeper waters. The modern commercial industry expanded the depth range with new diving technologies, but peaked in 1957 when 5.4 million pounds of abalone were harvested, and gradually declined since then. Humans replaced the sea otter as the primary predator on abalone... but we went a bit too far, we took too many. And wasting disease "finished" the job, at least in southern California waters. Now our ecosystems here have few abalone in them.

An ecological baseline is the state of an ecosystem at a given point in time against which future studies are compared so scientists can detect changes. Which of these periods above do we select as our baseline for ecological comparison? Unfortunately, it often depends on what year government or private grant money is available to fund a baseline study. Changes due to human impacts affect natural ecosystems more quickly. Starting a study in 2004 might establish a completely different baseline condition than one begun in 1994 or 2014, making it difficult to assess ecosystem health. But we need a good baseline to assess data collected in the future. Although they shift over time, some baseline is needed.

One study from the Monterey area proves the value of establishing a good baseline. In the early 1930's a Stanford Ph.D. student studied the tidepools near my marine biologist icon "Doc" Ricketts lab on Cannery Row. About 60 years later another Stanford researcher used the earlier study as a baseline for the exact same tidepools. He found that although both systems were of similar diversity (number of species), eight of nine warm-water species had increased and five of eight cold-water species had declined. Without the earlier baseline, it would have been difficult to obtain hard data that show the pattern of local warming and possible climate change. We needed such baselines 200 years ago, but it isn't too late to create a good set of them today. The provisions of the Marine Life Protection Act (MLPA) passed by the state legislature would go a long way towards implementing this, but it is stalled due to our budget ills. Let's not wait too long in light of all this shifting!

© 2004 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Stock values, like the number of individuals in the populations of different species, shift through time and create "shifting baselines" to determine gains or losses in your investment, or changes in the health of ecosystems.

This document maintained by Dr. Bill Bushing.
Material © 2004 Star Thrower Educational Multimedia