DIVE DRY WITH DR. BILL #778: SHIFTING BASELINES REDUX
Anyone who dives regularly should be aware of what is referred to as "shifting baselines." In a sense it is a scientific phrase to reflect the fact that ecosystems are dynamic and exhibit changes year-to-year or even day-to-day. Heck, if they were static I could have completed my investigation of kelp forests a few decades ago instead of constantly descending to observe the new and unusual.
My recent articles on the changes in species composition in Catalina waters highlight this. New species come and old species go, especially as driven by environmental changes due to factors such as ocean warming. Just over the past five to ten years we have witnessed a dynamic that has seen our giant kelp beds flourish and then be rendered almost non-existent due to short-term events like El Niños and The Blobs.
Those who dabble in the stock market are also aware of something similar to shifting baselines. For example, two friends who each hold stock in the same company may have completely different results despite that their stock is currently valued at the same level... let's say $100 a share. One friend bought his shares early for a mere $20 and thus has achieved a 400% increase in value. The other friend bought his shares at their peak, say $200. He has thus lost half of his initial investment. My results would undoubtedly be closer to his.
Many years ago I asked my grandfather how he was doing in retirement. He said the appreciation and dividends from his stock holdings were doing well. I replied "But you told me years ago not to buy stocks." He responded "That was then!" Several times in the past I have considered investing on a minor scale, and several of those tech companies I considered have produced incredible growth in value. Instead of living as a starving marine biologist, I could have become a financially successful human... but then I'd have missed all the fun!
Sadly we have relatively little quantitative data to tell us how marine critter populations in the past have fared over time. Few scientists were undertaking true quantitative research in the marine environment 100 years ago. What did take place was primarily in the intertidal environment. And, of course, SCUBA did not exist back then so diving scientists like myself couldn't submerge to get an accurate picture of what was beneath the surface. We have no true baseline data as to the status of populations back then.
I have been diving for 56 years, 49 of them here in SoCal waters. Although that represents decades, it is still a rather short period to judge long-term changes in the marine environment. However, I have observed a number of significant trends in our waters. On the negative side I saw the decline in abalone populations due to over harvesting and withering syndrome. Lobster populations no longer contain the older end of the age spectrum as much of their numbers are barely legal these days. I can remember the big boys and girls back in the day, but have only seen one monster lobbie in the past 10 years!
To establish a significant baseline in the natural world one cannot simply look at numbers over time. Two populations of lobster sampled decades apart may exhibit the same numbers in terms of individuals. However it is also important to look at the age structure of those populations. The early one may have had a nice age structure with many different levels. The current one may be largely composed of youngsters. Which is healthier?
There have also been positive changes as well. When I first started diving Catalina, I never saw a giant sea bass (Stereolepis gigas). Their numbers were seriously depleted back in those days due to over fishing. Following protections instituted by the State, their numbers have increased to the point where not seeing one on a summer dive is unusual. My son Kevin and I had a nice encounter with one on our dive last weekend and I've seen more than twenty on a single dive. White sea bass (Atractoscion nobilis) numbers have also increased due in large part to efforts by anglers and institutions to raise them in captivity. Funny that neither of these species are actually in the bass family... the first is a wreckfish and the second a croaker. Kind of like the Patagonian toothfish... er Chilean sea "bass."
Given our many impacts on the marine environment over the course of history, it is important to effectively manage ecosystems based on solid scientific data. However without adequate baselines with which to compare current conditions, we are largely operating blind. Scientists recognize this, but many politicians who have to open the purse strings seem not to. The surge in citizen science efforts such as those of REEF Check help fill the gap, but we still need a far more comprehensive approach to quantifying the status and dynamics of the marine environment. Perhaps we need a "Dow Jones average" for the sea?
© 2018 Dr. Bill Bushing. For the entire archived set of more than 775 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Abalone chowing down on kelp and spiny lobster on defense; giant sea "bass" and white sea "bass" (taken by angler, the few underwater images I have of them are too poor to use).
Anyone who dives regularly should be aware of what is referred to as "shifting baselines." In a sense it is a scientific phrase to reflect the fact that ecosystems are dynamic and exhibit changes year-to-year or even day-to-day. Heck, if they were static I could have completed my investigation of kelp forests a few decades ago instead of constantly descending to observe the new and unusual.
My recent articles on the changes in species composition in Catalina waters highlight this. New species come and old species go, especially as driven by environmental changes due to factors such as ocean warming. Just over the past five to ten years we have witnessed a dynamic that has seen our giant kelp beds flourish and then be rendered almost non-existent due to short-term events like El Niños and The Blobs.
Those who dabble in the stock market are also aware of something similar to shifting baselines. For example, two friends who each hold stock in the same company may have completely different results despite that their stock is currently valued at the same level... let's say $100 a share. One friend bought his shares early for a mere $20 and thus has achieved a 400% increase in value. The other friend bought his shares at their peak, say $200. He has thus lost half of his initial investment. My results would undoubtedly be closer to his.
Many years ago I asked my grandfather how he was doing in retirement. He said the appreciation and dividends from his stock holdings were doing well. I replied "But you told me years ago not to buy stocks." He responded "That was then!" Several times in the past I have considered investing on a minor scale, and several of those tech companies I considered have produced incredible growth in value. Instead of living as a starving marine biologist, I could have become a financially successful human... but then I'd have missed all the fun!
Sadly we have relatively little quantitative data to tell us how marine critter populations in the past have fared over time. Few scientists were undertaking true quantitative research in the marine environment 100 years ago. What did take place was primarily in the intertidal environment. And, of course, SCUBA did not exist back then so diving scientists like myself couldn't submerge to get an accurate picture of what was beneath the surface. We have no true baseline data as to the status of populations back then.
I have been diving for 56 years, 49 of them here in SoCal waters. Although that represents decades, it is still a rather short period to judge long-term changes in the marine environment. However, I have observed a number of significant trends in our waters. On the negative side I saw the decline in abalone populations due to over harvesting and withering syndrome. Lobster populations no longer contain the older end of the age spectrum as much of their numbers are barely legal these days. I can remember the big boys and girls back in the day, but have only seen one monster lobbie in the past 10 years!
To establish a significant baseline in the natural world one cannot simply look at numbers over time. Two populations of lobster sampled decades apart may exhibit the same numbers in terms of individuals. However it is also important to look at the age structure of those populations. The early one may have had a nice age structure with many different levels. The current one may be largely composed of youngsters. Which is healthier?
There have also been positive changes as well. When I first started diving Catalina, I never saw a giant sea bass (Stereolepis gigas). Their numbers were seriously depleted back in those days due to over fishing. Following protections instituted by the State, their numbers have increased to the point where not seeing one on a summer dive is unusual. My son Kevin and I had a nice encounter with one on our dive last weekend and I've seen more than twenty on a single dive. White sea bass (Atractoscion nobilis) numbers have also increased due in large part to efforts by anglers and institutions to raise them in captivity. Funny that neither of these species are actually in the bass family... the first is a wreckfish and the second a croaker. Kind of like the Patagonian toothfish... er Chilean sea "bass."
Given our many impacts on the marine environment over the course of history, it is important to effectively manage ecosystems based on solid scientific data. However without adequate baselines with which to compare current conditions, we are largely operating blind. Scientists recognize this, but many politicians who have to open the purse strings seem not to. The surge in citizen science efforts such as those of REEF Check help fill the gap, but we still need a far more comprehensive approach to quantifying the status and dynamics of the marine environment. Perhaps we need a "Dow Jones average" for the sea?
© 2018 Dr. Bill Bushing. For the entire archived set of more than 775 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Abalone chowing down on kelp and spiny lobster on defense; giant sea "bass" and white sea "bass" (taken by angler, the few underwater images I have of them are too poor to use).
