DIVE DRY WITH DR. BILL #829: DRIFT AWAY (WITH APOLOGIES TO DOBIE GRAY)
A good scientist should always be open to new information, even if it contradicts their own hypotheses. I first learned that as a Harvard student trying to help disprove plate tectonics (then known as continental drift). My mentor, Dr. H. Barraclough Fell, collected distribution data for many species groups and I entered it into IBM punch cards. Our early computer runs suggested that the current distribution of species could be explained by a polar meandering theory. Later that same data actually helped confirm plate tectonics.
When I moved to Catalina in August, 1969, Dr. Fell suggested I look at regional mechanisms to explain the distribution of marine invertebrate species. It was well known that an organism that possessed a planktonic larval stage could drift many miles from home before it settled. We wanted to look at mechanisms that could explain the dispersal of critters that lacked such larval forms. We also wanted to look at more efficient dispersal mechanisms that might bring a species to a new home in significant numbers.
We knew that large kelps such as our giant kelp (Macrocystis pyrifera) could break loose and travel over significant distances based on Dr. Fell's previous research in New Zealand. For 7 1/2 years my students and I conducted research on drift kelp dispersal thanks to a National Science Foundation grant. We would go out in the school's boat, the K-V, collect drifting kelp rafts (or paddies) well offshore and bag the holdfasts in large trash bags to bring back to the lab for dissection and analysis of any species attached to them.
While on board, we looked through the kelp fronds and found some critters, but our most intense search was in the tightly woven kelp holdfasts with many nooks and crannies to spread butter in... er, allow critters to hide securely and travel with the drifting kelp. In many cases the results were astounding. On one holdfast we found over 1,000 brittle stars. If they landed in a new location, there would be a large population with substantial genetic diversity to establish a new population or add new genes to the existing gene pool.
We found species like the brooding anemone, Epiactis prolifera, with youngsters attached to the parent. Since critters that brood their young often have short-lived larval stages that cannot disperse over great distances, this was important. Likewise females of any species that carried their eggs before releasing the hatched larvae could transport them over distances depending on how long the brooding period lasted.
Organisms that reproduced asexually were another important find. When I presented our data at one of the California Islands Symposia years ago, a marine biologist (Dr. Florence McAlary) had an "aha" moment. She studied the variable sea star (Linckia columbiae) but always wondered how it might have gotten to Catalina and the other Channel Islands. We had collected several of them on our rafts. Once an adult arrived here, it could cast off arms that would grow into new adults. It doesn't even need "two to tangle!"
One find that surprised a few other scientists was the presence of solitary cup corals transported on rocks attached to the holdfast. Actually a number of drifting holdfasts had rocks attached to them. Geologists found they had a mechanism for the transport of xenoliths, "alien" rocks from other areas dispersed into waters where those rocks did not exist.
Even fish can get a "lift" thanks to kelp rafts. Spearfishers know that drifting kelp paddies are often good places to lie in wait to take fish like yellowtail. A number of other fish also follow kelp rafts for protection if they wander away from shore. These fish can then be transported to places like Catalina where they can meet new friends.
Our research proved that drifting giant kelp could be a very effective mechanism to bring new species to our island waters. We even collected rafts of bull kelp (Nereocystis luetkeana) that proved kelps can drift on the order of at least hundreds of miles. This species of kelp is not known south of Pt. Conception, although many divers mistakenly call elk kelp (Pelagophycus porra) bull kelp.
Of course many factors affect critters hitching a ride on a kelp raft. They neeed to find something to munch on... possibly plankton or another critter on the raft. The fronds attached to the holdfast may senesce after a while losing their buoyant pneumatocysts and the raft sinks to the bottom. A hungry open water (or near shore) fish may nibble on the critters before they land. Or, sadly, many of the critters may lose the lottery if their raft lands on a sandy beach instead of their preferred rocky shores.
I had wanted to use this research as the basis for my doctoral dissertation at UCSB. I arrived there with my data all ready to go. However, my mentor there, Dr. Mike Neushul, suggested I try something a bit more technological so I spent six years collecting new data on the distribution of giant kelp around Catalina over a period of 60 years. It was certainly more cutting edge research, utilizing the technologies of satellite remote sensing and GIS (geographic information systems).
However, once I published papers on both research projects, I sent them to Dr. Wheeler North at Cal Tech since he was the other major giant kelp biologist in our region. He thought the GIS-based research added little to our knowledge but the kelp rafting project was something new and exciting. Go figure!
© 2019 Dr. Bill Bushing. For the entire archived set of over 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: The pre-PhD Dr. Bill in our researh vessel (the K-V) and drifting kelp raft or paddy; a variable starfish in a kelp holdfast and drifting attached to a rock; the brooding anemone and the numerous brittle stars in a holdfast (courtesy of Kevin Lee); a garibaldi looking for munchies before the critters land and drift kelp landing on a sandy beach.
A good scientist should always be open to new information, even if it contradicts their own hypotheses. I first learned that as a Harvard student trying to help disprove plate tectonics (then known as continental drift). My mentor, Dr. H. Barraclough Fell, collected distribution data for many species groups and I entered it into IBM punch cards. Our early computer runs suggested that the current distribution of species could be explained by a polar meandering theory. Later that same data actually helped confirm plate tectonics.
When I moved to Catalina in August, 1969, Dr. Fell suggested I look at regional mechanisms to explain the distribution of marine invertebrate species. It was well known that an organism that possessed a planktonic larval stage could drift many miles from home before it settled. We wanted to look at mechanisms that could explain the dispersal of critters that lacked such larval forms. We also wanted to look at more efficient dispersal mechanisms that might bring a species to a new home in significant numbers.
We knew that large kelps such as our giant kelp (Macrocystis pyrifera) could break loose and travel over significant distances based on Dr. Fell's previous research in New Zealand. For 7 1/2 years my students and I conducted research on drift kelp dispersal thanks to a National Science Foundation grant. We would go out in the school's boat, the K-V, collect drifting kelp rafts (or paddies) well offshore and bag the holdfasts in large trash bags to bring back to the lab for dissection and analysis of any species attached to them.
While on board, we looked through the kelp fronds and found some critters, but our most intense search was in the tightly woven kelp holdfasts with many nooks and crannies to spread butter in... er, allow critters to hide securely and travel with the drifting kelp. In many cases the results were astounding. On one holdfast we found over 1,000 brittle stars. If they landed in a new location, there would be a large population with substantial genetic diversity to establish a new population or add new genes to the existing gene pool.
We found species like the brooding anemone, Epiactis prolifera, with youngsters attached to the parent. Since critters that brood their young often have short-lived larval stages that cannot disperse over great distances, this was important. Likewise females of any species that carried their eggs before releasing the hatched larvae could transport them over distances depending on how long the brooding period lasted.
Organisms that reproduced asexually were another important find. When I presented our data at one of the California Islands Symposia years ago, a marine biologist (Dr. Florence McAlary) had an "aha" moment. She studied the variable sea star (Linckia columbiae) but always wondered how it might have gotten to Catalina and the other Channel Islands. We had collected several of them on our rafts. Once an adult arrived here, it could cast off arms that would grow into new adults. It doesn't even need "two to tangle!"
One find that surprised a few other scientists was the presence of solitary cup corals transported on rocks attached to the holdfast. Actually a number of drifting holdfasts had rocks attached to them. Geologists found they had a mechanism for the transport of xenoliths, "alien" rocks from other areas dispersed into waters where those rocks did not exist.
Even fish can get a "lift" thanks to kelp rafts. Spearfishers know that drifting kelp paddies are often good places to lie in wait to take fish like yellowtail. A number of other fish also follow kelp rafts for protection if they wander away from shore. These fish can then be transported to places like Catalina where they can meet new friends.
Our research proved that drifting giant kelp could be a very effective mechanism to bring new species to our island waters. We even collected rafts of bull kelp (Nereocystis luetkeana) that proved kelps can drift on the order of at least hundreds of miles. This species of kelp is not known south of Pt. Conception, although many divers mistakenly call elk kelp (Pelagophycus porra) bull kelp.
Of course many factors affect critters hitching a ride on a kelp raft. They neeed to find something to munch on... possibly plankton or another critter on the raft. The fronds attached to the holdfast may senesce after a while losing their buoyant pneumatocysts and the raft sinks to the bottom. A hungry open water (or near shore) fish may nibble on the critters before they land. Or, sadly, many of the critters may lose the lottery if their raft lands on a sandy beach instead of their preferred rocky shores.
I had wanted to use this research as the basis for my doctoral dissertation at UCSB. I arrived there with my data all ready to go. However, my mentor there, Dr. Mike Neushul, suggested I try something a bit more technological so I spent six years collecting new data on the distribution of giant kelp around Catalina over a period of 60 years. It was certainly more cutting edge research, utilizing the technologies of satellite remote sensing and GIS (geographic information systems).
However, once I published papers on both research projects, I sent them to Dr. Wheeler North at Cal Tech since he was the other major giant kelp biologist in our region. He thought the GIS-based research added little to our knowledge but the kelp rafting project was something new and exciting. Go figure!
© 2019 Dr. Bill Bushing. For the entire archived set of over 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: The pre-PhD Dr. Bill in our researh vessel (the K-V) and drifting kelp raft or paddy; a variable starfish in a kelp holdfast and drifting attached to a rock; the brooding anemone and the numerous brittle stars in a holdfast (courtesy of Kevin Lee); a garibaldi looking for munchies before the critters land and drift kelp landing on a sandy beach.
