Since I have now recieved 5 emails informing me of this thread, I feel almost compelled to respond.
I am familiar with a small number of papers that Julian has referred to regarding habitat, etc. I would not consider myself extremely familiar with the literature on this subject, but likewise I do think it would be nice if he were to include in his response those particular references he uses to make the points so that we were not left to merely take his word for it, and would be in a better position to examine those veracity of those references critically.
I think this issue is very similar in many ways to the zebra mussel invasion. Initially a nightmare, time has tempered the invasion as it has in fact provided some benefits. However, any potential benefits aside, the inasion of non-endemic species is a historical fiasco and an ecological taboo. The number of pertinent subjects in the literature from the land snails to feral cats and cane toads Eucalyptus, rats, fire ants, algae, is immense. Someone carefully scrutinizing the literature could probably find cases where such introductions were ultimately beneficial. The vast vast majority of cases, however, have resulted in conditions ranging from mildly negative to environmentally catastrophic.
In any event, remotely condoning, justifying or rationalizing introductions of non-native species, non-endemic species or invasive species is , to put it mildly, not very ecologically responsible, irrespective of the validity of laymedia reports which are, in general, to be avoided as a source of factual information.
In regard to C. taxifolia, it should be obvious that entire congresses, symposiums, and task forces wouldn;t be devoted to this issue were it merely an exaggeration and/or beneficial. Simply providing habitat is not necessarily a good thing. I think the artifical reefs issue has plenty of documentation to support this. Providing habitat when the habitat itself may be naturally depauperate is not necessaily a good thing. Providing altered habitat is not necessarily a good thing. Providing habitat for some things at the detriment of others is not necessarily a good thing.
In regard to nutrient absorption, thats great in an aquarium, although I have argued that Caulerpa has to be one of my least favorite algae in aquariums, too. The wild is not an aquarium. Removing nutrients means removing energy sources for other native flora and fauna.
In regard to aquariums, Caulerpa spp. produce a wealth of toxins. The release of gametes can wipe out a tank. Rhizomes have acidic secretions that erode limestone. Removal of it can be nearly impossible. Caulerpa can penetrate living coral tissue, and has actually pierced through Xenia in my own tank in the past. Not only do I disagree with the statement that Caulerpa makes conditions in the aquarium better, in whatever unsubtantiated and undefined terms that might be taken, but I cannot see the correlation with aquariums and invasion into non-native habitats in the wild whatsoever.
Also, I think the documentation of caulerpine toxins on fish is well established and to support this and other points, I have found the following links with references, perhaps more than the links themselves (example, the french link with a very good reference list), for further information. Also are two reports from groups/persons that should be taken as extremely credible (note the anstaskforce.gov report with references).
http://www.com.univ-mrs.fr/gisposi/gistest/ctaxifolia/biblio/content.html
http://www.sci.sdsu.edu/CMI/swilliam/swilliam.htm
http://www.ridnis.ucdavis.edu/caulerpaconference2002info.html
http://plants.ifas.ufl.edu/database.html
http://www.anstaskforce.gov/Caulerpa.htm
from a Florida Marine Fisheries/SeaGrant site:
in the Mediterranean, Caulerpa taxifolia occupied 1 m2 in 1984; 30 ha by 1991; 1000-2000 ha by the end of 1993
* in the Mediterranean, the alga is causing a "major ecological event" (Boudouresque et al., 1995)
* in the Mediterranean, Caulerpa taxifolia invades the dominant seagrass, Posidonia oceanica, and in invaded areas able to kill up to 45% of Posidonia shoots in one year (Villele and Verlaque, 1994)
* where it is found in the Mediterranean, other native seaweeds are being more or less totally replaced
* the numbers of individuals of Mollusca, Amphipoda and Polychaeta in Caulerpa taxifolia meadows is greatly reduced (Bellan-Santini et al, 1996)
* Caulerpa taxifolia is toxic to herbivores such as sea urchins and fish; where the plant is the sole food source, then these herbivores are eliminated
* caulerpenyne extract inhibits or delays the proliferation of several phytoplanktons of the marine food chain (Lemee et al., 1997)
Bellan-Santini D, Arnaud PM, Bellan G, Verlaque M. 1996. The influence of the introduced tropical alga Caulerpa taxifolia, on the biodiversity of the Mediterranean marine biota. J. Marine Biological Association of the United Kingdom 76(1):235-237
* Boudouresque CF, Meinesz A, Ribera MA, Ballesteros E. 1995. Spread of the green alga Caulerpa taxifolia (Caulerpales, Chlorophyta) in the Mediterranean: Possible consequences of a majro ecological event. Scientia Marina 59(Dec)Suppl. 1:21-29
* Boudouresque CF, Meinesz A, Verlaque M, Knoepffler-Pegue M. 1992. THe expansion of the tropical alga Caulerpa taxifolia (Chlorophyta) in the Mediterranean. Cryptogamie-Algologie 13(2):144-145
* Boudouresque CF, Bellan-Santini D, Belsher T, Duclerc J. 1992. The introduction of the green alga Caulerpa taxifolia into the Mediterranean: The repercussions for the indigenous communities. Communication Presentee Au 6th European Ecological Congress, 7-12 Sept 1992, 52:88-89 (Abstract)
* Ceccherelli G, Cinelli F. 1999. Effects of Posidonia oceanica canopy on Caulerpa taxifolia size in a northwestern Mediterranean bay. J. Experimental Marine Biology and Ecology 240(1):19-36
* Chisholm JRM, Joubert JM, Giaccone G. 1995. Caulerpa taxifolia in the northwest Meditteranean: Introduced species or migrant from the
Red Sea?. Comptes Rendus de L'Academie des Sciences 318(12:1219-1226
* Chisholm JRM, Dauga C, Ageron E, Grimont PAD. 1996. Roots' in mixotrophic algae. Nature 381:382
* Delgado O, Rodriguez Prieto C, Gacia E, Ballesteros E. 1996. Lack of severe nutrient limitation in Caulerpa taxifolia (Vahl) C Agardh, an introduced seaweed spreading over the oligotrophic northwestern Meditteranean. Botanica Marina 39(1):61-67
* Jousson I, Pawlowski J, Zaninetti L, Zechman FW, Dini F, Di Guiseppe G, Woodfield R, Millar A, Meinesz A. 2000. Invasive alga reaches California. Nature 408:9 November 2000
* Lemee R, Pesando D, Issanchou C, Amade P. 1997. Microalgae: a model to investigate the ecotoxicity of the green alga Caulerpa taxifolia from the Mediterranean Sea. Marine Environmental Research 44(1):13-25
* Lemee R, Pesando D, Durand-Clement M., Dubreuil A. 1993. Preliminary survey of toxicity of the green alga Caulerpa taxifolia introduced into the Mediterranean. J. Applied Phycology 5:485-493
* Meinesz A, Benichou L, Blachier J, Komatsu T, et al. 1995. Variations in the structure, morphology and biomass of Caulerpa taxifolia in the Mediterranean Sea. Botanica Marina 38:499-508
* Meinesz A, de Vaugelas J, Hesse B, Mari X. 1993. Spread of the introduced tropical green alga Caulerpa taxifolia in northern Mediterranean waters. J. Applied Phycology 5:141-147
* Ribera MA, Ballesteros E, Boudouresque CF, Gomez A, Gravez V, editors. 1996. Second Internationl Workshop on Caulerpa taxifolia, Barcelona, 15-17 December 1994. University of Barcelona. 457 pp.
