I’m just now getting around to exploring the various posts and comments on CFI. This conversation really caught my attention. As I have a great interest in the presence of endocrine disruptors, the referenced article is helpful to me. I had, and have, misgivings about burdening the forum with this story. It is long and probably far to much to read in forum post, but I thought I’d go ahead and do it anyway. I think it is an extremely important topic, not only to esoteric science, but very much so to the folks like you and me that live in the changing environments we call home. The dangers of running across the Interstate highway at times of peak traffic are very obvious. The dangers, present and rapidly growing, of endocrine disruptors in our aquatic and terrestrial environments are no less dangerous, just much more greatly hidden and much more slowly evidenced.
I’m an old (scary to say that word, but it’s true), retired marine/fishery biologist and marine aquaculturist now working pretty much full time on a project to develop the technology for the controlled culture, spawning through juvenile, of Diadema sea urchins. It’s a long story. The short version is that 92 to 98 percent of all of this species of sea urchins, the long spined urchins of the Caribbean, Bahamas, and Florida were killed in 1983 in the greatest marine animal pandemic to ever occur.
We thought their populations would soon rebound but that was not the case. There are are still random small populations and individuals present in these areas but for all intents and purposes, they are ecologically extinct. This is very important to health of coral reefs in western tropical Atlantic because they are, or were, the keystone herbivores in this vast area, maintaining the balance between slow growing corals and fast growing macro algae. Their demise resulted in rapid and intense algal overgrowth of the coral reefs. This changed the ecology of the reefs and subsequent algal overgrowth of the reef prevented settlement and survival of juvenile corals, urchins, and many other species.
This is but one of the major problems that are changing the ecosystems of our oceans. In this case, however, if we can rear and place juvenile Diadema on our coral reefs and make up for the lack of natural recruitment of juveniles with hatchery bred juveniles, we can ecologically restore some coral reefs thus helping this keystone herbivore to recover and return to the reefs.
I’ve worked on development of this culture technology for almost 10 years now and in the summer of 2012, I and the Mote Marine Laboratory here in the Florida Keys were very close to completion of this project. We were at the point where we were rearing thousands of larvae through the larval stage and learning how to best provide the environments for high survival of the settled juveniles. Suddenly, at both locations, my little lab on Lower Matecumbe and 50 miles away, the Mote lab, the larvae would no longer form rudiments. At about day 24, the larvae form a tissue rudiment just above the gut that is actually the development of the early juvenile within the body of the larvae. The rudiment/juvenile coexist for another 20 days and and when the rudiment is mature and ready for metamorphosis into a benthic juvenile, the larvae moves from the plankton down to a coral reef or other suitable benthic environment, and attaches to the bottom. Metamorphosis happens and the new benthic, radially symmetrical, juvenile that formed from the pelagic, bilaterally symmetrical, larvae begins to feed on benthic algae and takes on the typical form and function of sea urchin.
Well if you have read this far, you are probably curious as to what this has to do with endocrine disrupting chemicals. I had a variety of problems with rearing Diadema through the larval stages from 2009 through 2012, many of these problems concerned the structure of the culture vessel and the micro algae food, however success in rearing them into the juvenile stage occurred in most rearing runs. Because of these vague problems, I was beginning to strongly suspect that some variable factor was interfering with larval development and began researching the possibility of endocrine disrupting chemicals in Florida Bay water.
Suddenly, in the summer of 2012, the larvae in my little lab and the larvae in larger project at the MOTE lab would not form rudiments. The larvae remained healthy and I could keep them in culture for over 90 days, but they, to an individual, would not form rudiments. The MOTE lab turned to other projects but I kept working on the problem. For three years I tried everything I could with water filtration (I used highly filtered water from Florida Bay, a variable problem until 2012) and micro algae feed with no change in larval lack of rudiment development. Now hormone activity is critical to changes that must occur during larval development into the juvenile.
The first rearing run in the spring 2015 resulted in not a single larva in either of two culture vessels forming a rudiment. Knowing that endocrine disruptors were most likely present in Florida Bay waters and trying without success to clean the water to the point that normal larval development could occur, and failing completely in every rearing run to recover the early and repetitive success with rudiment formation, I made arrangements for an RO machine to clean the tap water and obtained a source of a salt mix to make artificial sea water. On the first trial in the summer of 2015, I ran two culture vessels, one with the processed natural sea water, the other with artificial sea water. Not a single larvae in the natural sea water culture formed a rudiment. Almost every larvae in the artificial sea water culture formed a rudiment and developed to the point of metamorphosis. Although the culture failed at this point due to problems with micro algae culture, the outcome was obvious. The next run in the fall of 2015, both culture vessels were run with artificial sea water and almost all larvae in both vessels formed rudiments and developed to the point of metamorphosis. This time bacterial infection at the point of metamorphosis prevented survival of the early juveniles.
Diadema larvae are extremely difficult to rear. Only four labs, U of M, my personal lab, MOTE Laboratory, and the Florida Aquarium have been able to produce surviving juveniles, which is why so few attempts have been made on their culture. My next spawn and rearing run will take place in a couple of weeks, and now without the confusing and variable factor of the possible effects of endocrine disruptors in Florida Bay waters, I think I now have the understanding of the culture requirements needed to make the final breakthroughs, which hopefully should encourage labs with proper facilities and ability to get grants to take up the project.
Why I shared this topic here is to make the very important point that the problem of endocrine disruptors in our freshwater and marine environments is a great and growing problem. One that we are just beginning to learn the magnitude and immense threat that it poses. And we know very little about the kinds of endocrine disruptors that are present in our marine waters, when they are present, their concentrations, what organisms and at what stages of life they may affect, and how to combat this threat. I did publish an article on this problem as it affects my limited research. I will publish more soon when more information is developed.
Endocrine Disruptors: On finding invisible pollution in my back yard
CORAL January/February 2012, Volume 9, Number 1