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03/20/2006

Ground Water and Reefs

Wolcott Henry of the Henry Foundation and a member of the BOT directed us to an interesting article in the Stanford News-Service on the effects of groundwater on coral reefs. The study, published in the January 2006 edition of Limnology and Oceanography, found that groundwater is an important source of nutrients for coral reefs. The effects will be studied using a technique that measures the amount of radium (large measures of which are found in groundwater and almost none in salt water) in the sea to determine degree of groundwater discharge. This is significant in our work on coastal resource management because the amount of groundwater pollution may explain degrees of coral reef deterioration..or diversity?

According to Ed Tongson, “There's also a paper that shows that coral diversity increases when stressors (such as pollution) increases. This may explain why Balayan and Verde passage may have higher coral diversity than pristine areas such as Tubbataha. There are more urban areas in Batangas which discharge polluted waters to the open reef areas and yet you have the highest coral diversity in these areas.”

Yeb Sano needs to see more evidence. “It runs against established knowledge in coral reef science. Generally, since corals depend on photosynthesis in order to thrive, relatively low-nutrient water is necessary to ensure optimal development. It can be said that diverse conditions yield diverse variations. Nevertheless, based on most scientific findings, I can’t imagine that pollution can be a single factor that engenders coral diversity. From what I understand about natural history, diversity is a function of evolution, not of adaptation. As most studies say, correlations cannot be determined until further studies are made. But definitely, it has been established that pollution is one single factor that can harm coral reefs. Also, increase in diversity doesn't necessarily mean improved reef conditions.”

It’s an important discussion all around and we'll post any new findings on this thread.

00:45 Posted by in Marine | Permalink | Comments (2) | Email this | Tags: Ecology & Environment

Comments

Just to correct, pollution is not the single factor but as a stressor, it is one of three primary factors that controls diversity and abundance. The paper states that "disturbance, competition and stress are three primary factors controlling diversity and abundance of plants and animals in natural communities." Hence, evolution and adaptation are not exclusive pathways, they are two sides of the same coin. (Also, a good example is the evolution of of germs.)

It''s valid when you mention "An increase in diversity doesn't translate to improved reef conditions". And the converse, "improved reef conditions doesn't translate to coral diversity" is also valid. While Gomez classifies coral cover > 75% as "Excellent," the score does not reflect other indicators useful for conservation. In fact sites with ">75% coral cover are frequently composed of mono-specific stands with low spatial complexity, provide relatively poor fish habitat and reef fisheries potential".

The paper argues that we should abandon Gomez' methods using coral health as basis for conserving biodiversity. It says that reefs having mixed coral morphologies that have the highest conservation class (CC=4 reefs) should be conserved. These are characterized by high coral species diversity, spatial complexity and rare species occurrence. However, under Gomez' standards, they are not necessarily excellent as they have intermediate values for coral cover (generally 40-60% coral cover). In addition, the occurrance of rare corals are not factored in the Gomez measurement. The authors claims "number of rare coral species was not significantly correlated with live coral cover, reef condition or coral mortality index. (p. 8)".

Note that Mindoro and Batangas have high number of rare corals but exhibit lower live coral cover than Tubbataha. The next question is what triggers the emergence of rare corals in these areas. I can only hypothesize that being near urban areas, their reefs are also subject to stressors (due to natural or man-made occurrences) which may contribute, along with other factors, to the evolution of a new subspecies. What are the other factors? Well, there's the Carpenter paper hypothesizing why Verde passage is the center of the center of marine biodiversity, but that's another story.

Posted by: Ed | 03/20/2006

Based on what I learned from Biogeography, adaptation is one of the fuels that drives evolution. Given a long time of isolation new species is formed provided there is reproductive isolation. In some cases, adaptive radiation ensues resulting to higher diverstiy.

Posted by: Ruel Pine | 03/20/2006