[Coral-List] Are we forgetting what reefs used to look like?
James M. Cervino (Marine Biologist)
cnidaria at earthlink.net
Sun Oct 8 23:20:06 EDT 2006
Dear Mr. Borneman
There is such a wealth of information on this topic that it seems fruitless to even begin any sort of literature "justification" in posts.
Cervino: If you call citing the peer-review literature from the people and LOCALS that have watched the decline and studied these reefs during the past 60 years fruitless as a means to justify excessive anthropogenic nutrient enrichment? Then, you are discrediting the hard work of our coral reef forefathers.
Mr. Borneman: Workshops, meetings, special issues of journals, reports, and more have debated bottom up and top down factors for decades and at this point if we do not realize that both, and more, play roles in community structuring then we are indeed in trouble.
Cervino: I am talking about the Breached levels of nutrients, the variation in gradients along a nutrient profile transect containing the algal species that are proliferating along that gradient. I trust the data from the local scientists that conducted long term research on the Island of Jamaica not from a few that conducted short studies on that island during a summer break.
For example the following was taken from Proceedings 8th International Coral Reef Symposium 2:2093-2096. 1997. Community-Based Whole-Watershed and Coastal Zone Management in Jamaica T. J. Goreau1,2, L. Daley1, S. Ciappara2, J. Brown1, S. Bourke2, & K. Thacker1 Negril Environmental Protection Trust, Negril, Jamaica Port Antonio Marine Park and Forest Corridor Project, Port Antonio, Jamaica. QUOTE JOURNAL Massive mortality of the black sea urchin Diadema antillarum in 1983 coincided with algae proliferation in some areas such as Discovery Bay which was simultaneously going eutrophic, but this was not generally true in other parts of the island. Algae proliferation now extends all the way down the fore-reef slope even though Diadema were never very abundant in that habitat, being largely confined to shallow fore reef and protected back-reef lagoonal areas. Diadema grazing was a significant factor in controlling algae in the past when nutrients were lower, but this is no longer the case. In most areas where Diadema populations have recovered they are unable to consume most of the algae due to the extremely rapid growth rates of algae fertilized by excessive nutrients. Diadema which used to forage long distances now are observed to graze only in very limited halos around their resting sites, leaving abundant masses of algae around them. Reefs which are free of local landbased sources of nutrients have low algae abundances even where there has been no recovery of Diadema populations and where fish are also very scarce due to intensive fishing efforts. Young corals are rare wherever algae biomass is high, but are abundant in areas remote from human stress.
Mr Borneman: The polarization of views regarding factors contributing to coral reef decline or to the reasons for the existence of alternate stable reef communities, such as phase shifts, as being due to a single dominant ecological, biological, or environmental factor serves to hinder understanding unless, of course, that particular reef is strongly influenced by one or a few dominant factors.
Cervino: I am not polarizing Mr. Borneman, because this is not a discussion about reef decline in general! it pertains to algal rainforests smothering corals due to high levels of N&P. This is not a discussion regarding a multiplex of factors that cause reef decline. Therefore we shall keep this discussion about an urchin, fish grazers and nutrient enrichment that causes algal rain-forests smothering corals. The major factor preventing coral recovery is due to the abundance of fleshy algae which smother and kill corals and prevent young corals from settling.
Mr Borneman: How then do you explain luxuriant coral growth to the near exclusion of macroalgae in nutrient rich lagoons (many examples in the Pacific, even with high sedimentation rates from decaying vegetation) but macroalgal abundance in remote, offshore nutrient poor and population- free areas (e.g Mona Island, Glover's reef)?
James: Are you calling Glovers Reef healthy as well as looking like it did before the birth of the algal rain-forest during the late 1980s and early 90s? According to Miriam Huitric and Melanie McField3, (2000). Effects of multiple disturbances on hard coral recruits in Glovers Reef Atolls lagoon, Belize. Along with numbers of other publications including Lapointe B. Limnol. Oceanogr., 40(3), 1995, 625-633. 1995, by the American Society of Limnology and Oceanography, Inc. A comparison of nutrient-limited productivity in Sargassum natans from neritic vs. oceanic waters of the western North Atlantic Ocean
Mr Borneman: Historically, I think, it is pretty well demonstrated that the Caribbean was out of whack before anyone really started studying it, and since then I think it is also pretty well established what a critical role Diadema played throughout most of the Caribbean in more recent times.
Cervino: I respectively disagree with this comment. Again; you are so wrong here, as you are not crediting the people that have been looking at the real long term changes in coral and algal cover in the past 6 yrs. I am talking about the people that have not forgotten, that show images and data of what it used to look like. These people can tell you exact colonies that have become extinct due to algal lawns. These scientists have diaries and data points of the changes way before the urchin died off. I have been diving since 1979 and remember what it looked like. I have stared at corals for 27 years and in this short time have seen dramatic changes in algal species along a nutrient gradient.
Mr Borneman: There are currently sites with relatively high Diadema and relatively low coral cover, and conversely low Diadema and high coral cover. Maybe the the historical grazing factors are forever lost, and maybe Diadema is rightly credited for allowing for the conditions Martin alludes to in his words and the studies cited (I think he is, fwiw), for indeed where there are a lot of Diadema, there tends not to be much macroalgae.
Cervino: Yes this is correct the areas with relatively high Diademia and low coral cover are a case in which the nutrient concentrations are rising and the urchin cannot eat the algal mass fast enough! This could be a case in which the urchin cannot keep up with the explosive growth rates of the filamentous algal species that are dominating the reefs today. Have you measured nutrients at these locals? If so what are they? The limiting values for tropical reefs, above which algae are observed to overgrow corals, are 1 micromolar N and 0.1 micromolar P (Lapointe, 1995).
Cervino: I cannot comment on closed systems as the expert that I trust would be Mr. Martin in that case. His comments are valid when it comes to a closed system, however, Mr Borneman, therefore I must recluse myself from that part of the discussion.
For the people that are commenting on Jamaica: The below quote was taken from that same journal I quote above. For those of my respected colleagues who continue to comment on Jamaica that are interested in data from scientists that lived on the island and have real time data to back up the claims please read below.
One measure of sustainability that is especially relevant to coral reef protection in a densely populated country like Jamaica is the level of nutrients in coastal waters with regard to the acceptable upper limits required to prevent algal overgrowth. Any marine ecosystem will undergo eutrophication, excessive proliferation of nuisance algae, when nutrient inputs are too high, but coral reefs are the most sensitive of all marine ecosystems to excess nutrients. Unfortunately, until the recent establishment of appropriate nutrient standards for coral reefs, there was a tendency to uncritically adopt standards from cold developed countries. Those standards were developed for estuary ecosystems. These habitats receive large amounts of runoff from spring snow melt, are low in biological diversity, and are dangerously inappropriate for tropical coral reef ecosystems.
The limiting values for tropical reefs, above which algae are observed to overgrow corals, are 1 micromolar N and 0.1 micromolar P (Lapointe, this volume). Wade's measurements of nutrients in Negril's coastal waters during 1991 (this volume) show that concentrations were more than 10 times above the acceptable limits. Nutrients inputs to the Bay are clearly way beyond those the reef corals can tolerate. By the critical reef nutrient criterion, Negril is unsustainably overdeveloped by a factor of more than 10 times. With existing patterns of per-capita nutrient release, the area has more than 10 times more people than the reef can stand.
An illustration of the effect of population density on human carrying capacity of reefs is illustrated by the situation in Moorea, a South Pacific island with a population of only 4,500. Club Med's 400 room complex is the only large tourist site on the island, and its largest single source of sewage, which undergoes secondary treatment before ocean discharge. Only a single species of algae, Turbinaria ornata, was found at all reef sites. This species is tough, unpalatable to fish, and adapted to live on very high wave energy shores and reef crests. Algae were extremely rare in reefs all around Moorea, far less common than anywhere in Jamaica today, except right in front of Club Med bathing beach. The resort's ocean sewage outfall pipe was buried beneath the beach and ran along the bottom to a depth of about 20 feet. It had clearly been blocked underground for some time when examined in July 1991, because the end of the pipe contained undisturbed marine sediments and was occupied by organisms which had settled and grown inside. Instead of emerging from the pipe, sewage apparently trickled out through the beach sand, stimulating growth of large slimy mats of cyanobacteria on the sand bottom, and dense growths of smothering green algae identical in appearance to Chaetomorpha linum, which has been a major problem in eutrophication of Jamaican reefs (Goreau, 1992). This alga was seen nowhere else on Moorea, including in front of the sewage outfalls of other smaller resorts, which range up to around 20 rooms. This evidence suggests that the human carrying capacity of Moorea reefs are to date exceeded only in front of the single largest resort. In terms of population density and sewage generation, Negril is about equivalent to 7 solid miles of Club Med., and is therefore likely to have a population density which exceeds the reef human carrying capacity throughout. Consequently the reef's survival cannot be sustained in the long run unless there is at least a ten fold improvement in the efficiency of technology used to intercept and remove nutrients before coral mortality becomes so severe that recovery is impossible. The same is the case in most areas of tourism development in Jamaica and in most other coral reef countries around the world. They are, in effect, racing each other to capitalize off short term value of their reefs before they destroy them.
The situation is far worse than Negril in many other parts of Jamaica, especially near Kingston, Montego Bay, Ocho Rios, St. Anns Bay, and Discovery Bay. For the reefs to recover, either there needs to be many less people living in these areas, or they need to adopt technology which treats and removes all excess nutrient inputs to the coastal zone. The carrying capacity is highly dependent on the type of technology employed to contain or prevent human impacts to the environment. This paper concludes that so much of Jamaica's coastlines are now over-developed with regard to current environmental practices that marked technology improvements in sewage treatment are needed to allow reefs in these areas to recover. Areas not yet impacted need protection from damage by inappropriate "development" because it will be far cheaper to protect their reefs than to restore them after they are degraded.
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