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Fighting Algae in Kaneohe Bay Science, Volume 319, Issue 5860, dated January 11 2008
Dear Jennifer, Thanks for your clarifications. As you can imagine this was written very tongue in cheek, more as a joke than anything, and I was certain it didn't have a snowball's chance in hell of being published (I wish I could get papers that are really original published as easily!). Also I did not realize that you and Cindy were involved! I'm a compulsive weeder and gardener, and for years I would heavily weed the algae around the corals in Jamaica that I was making long term growth measurements on in the 1980s. It made me feel good, but made no practical difference because I couldn't do it constantly and the nutrients were just too high. Sometimes we would weed our Gracilaria mariculture lines half a dozen times a day to get rid of the huge Chaetomorpha blooms smothering them. A real fool's errand....... I think that these algae populations are probably largely nutrient driven, but they depend on pulses of runoff with large amounts of non-point source nutrients from road runoff, lawn fertilizer, and golf course drainage, so that you could easily get nutrients below threshold values at times when there have not been large recent inputs. These algae respond in color and branching pattern very strongly to nutrients. But because they are so massive and wave resistant with phycocolloids they can hold onto nutrient inputs for a long time and so have a good chance of surviving the periods of no or slow growth between pulses that high nutrient algae like Ulva and Cladophora, and even fairly tough but smaller algae like Hypnea and more brittle ones like Acanthophora just can't. If we can get in the field enough to document the impacts of shutting off the sewage outfalls I'm sure we'll just find what happened in Kaneohe Bay in the old days when they made the sewer outfall longer and deeper. But EPA is STILL denying that the algae blooms are caused by nutrients, based on the nonsense that Hughes published, and trying to blame anything but sewage. Yesterday one of my Florida colleagues spoke to me on his way back from a meeting with the Governor's Office in Tallahassee, and sure enough the EPA "expert" showed up to say that there was "no evidence" that sewage caused the algae blooms around the outfalls, even though the algae blooms, zoned concentrically around the outfalls and stretched out in the direction of the current flow, have been documented for years by Ed Tichenor to expand and contract predictably with fluctuations in the amount of sewage they pump out of them (information only available thanks to the Freedom of Information Act and repeated threats of law suits). I'll get the Turks and Caicos paper to you as soon as I can. It will be most interesting to follow up on the algae, diseases, and bacterial associations. Best wishes, Tom On Jan 11, 2008, at 2:04 PM, Jennifer Smith wrote: Dear Tom /et al./, Thanks for your email. I wholeheartedly agree that "exotic algae" as a whole are not free of nutrient influences and I spent the better part of 6 years while working on my PhD studying the nutrient dynamics of invasive algae in Hawai'i. I have found a lot of evidence and very large effects of nutrients on certain species of algae that commonly form blooms in Hawaii (both native and exotic species) such as /Cladophora/, /Ulva/ and /Hypnea/. Kane'ohe Bay is a entirely different beast than most other reef areas on the planet as anyone who has spent time there can attest to. There are many overlapping disturbances in the bay which in combination have allowed several species of exotic algae to overgrow the reefs. Different reef areas are dominated by different species such as /Eucheuma denticulatum, Gracilaria salicornia, Acanthopora spicifera/ and /Kappayphycus/ to name a few. While Kane'ohe Bay was once the poster child for a eutrophic reef, today there are no large point sources of nutrients entering the water and nutrient dynamics are strongly tied to fresh water runoff events driven by large rainstorms. Based on a number of growth experiments that I have done both in the field and in the lab /Eucheuma/ and /Gracilaria /can maintain positive growth in low nutrient water suggesting that these species do not NEED high nutrients to grow. Further the /in situ/ growth rates are not huge but more slow and steady. So over the last 30 years they have gradually spread throughout the bay and because herbivores don't eat them they essentially grow without any control. This is not to say that if a bunch of sewage got dumped into the bay today that they would not explode in growth but I would guess that other species would be better competitors under eutrophic conditions. Lastly, our goal with the Super Sucker is to remove the biomass that has been building up for many years-much of which forms extensive mats that block access to the benthos for other species and smothers corals. These species are causing reductions in diversity and coral cover simply based on their growth habit. We have a paper that will hopefully come out this year that shows these impacts. So, by removing the biomass and by keeping areas free for some time we are at least allowing corals and other inverts and algae to gain access to the benthos and perhaps recover. We do not think that the super sucker will eradicate these species but rather will reduce the loss of coral and perhaps help with restoration. We hope this makes sense and let us know if you have any other questions. We agree that nutrients can have huge effects on reefs and have shown this in several cases but they are not the whole story for Kane'ohe Bay exotics. Tom, I look forward to seeing you new paper-please send me a PDF when available. Happy New Year and Best Regards, Jennifer et al. Thomas Goreau wrote: Dear Jennifer and Cindy (and your colleagues whose emails I don't have), I have just gotten the on-line Science and was astonished to see my letter (which I never thought they would publish) and your response. I'm not so sure that exotic algae are free of nutrient influences. Lets see if these places remain algae free for the long term...... http://www.sciencemag.org/cgi/content/full/319/5860/157b?sa_campaign=Email/toc/11-January-2008/10.1126/science.319.5860.157b Is Gracilaria the main problem there, or is it Eucheuma and/or Kappaphycus? These can have strong holdfasts that may remain and keep growing after the bulk of the plant is pulled off? Cy Macfarlane and I did a lot of work on the nutrient physiology of all the Caribbean Gracilarias in the 1980s and all of them responded strongly to nutrients, while some of them were susceptible to herbivory. I and others have recently managed to get the offshore sewage outfalls in SE Florida and in St Croix shut down and replaced by land water (and nutrient) recycling, and we expect the algae blooms smothering corals in rings around them to die back. If that happens this will provide strong support for the bottom-up controls on algae productivity. The Hughes papers you report claiming that algae in Jamaica result from herbivore loss are garbage, his sites went eutrophic from coastal development and sewage inputs over the course of his study but he never recognized this, never measured nutrients, and he did not understand algae nutrient ecology at all. He claims that his major site had no land-based sources of nutrients but in fact it was immediately downstream from the largest spring and river source of high nitrate on the north coast of Jamaica, and a cattle farm at the mouth of the river shoveled all the cow crap from the pens into the river every morning. The locals all complained to me, and you could smell the stuff in the water at Hughes' allegedly nutrient-free site. Jennifer, my paper on the correlations of different species of algae with different coral diseases in Turks and Caicos is now accepted and will be published in July. It cites your work on algae as bacteria reservoirs, and the data leads to specific predictions as to which algae are likely hosts for certain diseases that will be worth following up. I can send a pdf when I get the galley proofs. Cindy, there is a good chance that I may pass through Hawaii some time this year and I'll try to contact you if that happens. Best wishes, Tom Thomas J. Goreau, PhD President Global Coral Reef Alliance 37 Pleasant Street, Cambridge MA 02139 goreau@bestweb.net <mailto:goreau@bestweb.net> http://www.globalcoral.org
Jennifer E. Smith, Ph.D. Postdoctoral Fellow National Center for Ecological Analysis and Synthesis University of California, Santa Barbara 735 State St. Suite 300 Santa Barbara, CA 93101 Office: (805)892-2522 Email: jsmith@nceas.ucsb.edu <><<><<><<><<><<><<><<><<><<><<><<><<><<><<><<><<><<><<><
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