Sunday, August 24, 2008

Shipwrecks threatening coral reefs ecosystems

Coral reefs habitats are home of many unique ecosystems with extremely rich biodiversity. Preserving coral reefs is important not only for corals but for many other species that rely on coral reefs for shelter and reproduction. The main reason why many coral species are being endangered are warmer waters as the result of global warming phenomenon. But climate change is not the only factor threatening coral reefs, there are also other factors like for instance shipwrecks.

Recent U.S. Geological Survey study showed that shipwrecks on coral reefs may have serious impact in increasing the invasion of unwanted species which could even destroy unique biodiversity of life that has its habitats in these areas. These invading species could completely overtake the reef and eliminate all the native coral, making unrepairable damage to this rich biodiversity.

One of these unwanted species is Rhodactis howesii —an organism related to sea anemones and corals. Rhodactis howesii population increased exponentially in the last couple of years and scientists also documented extremely high densities of Rhodactis howesii that progressively decreased with distance from the ship, also confirming high densities of Rhodactis howesii around several buoys.

This study was conducted at Palmyra Atoll National Wildlife Refuge in the central Pacific, a relatively remote, comparatively pristine area where there was almost none human activity since the World War II. According to Dr. Thierry Work, the lead author of the study and a scientist at the USGS National Wildlife Health Center this infestation is the beginning of future catastrophe.

As Dr. Work said: "Given the ability of Rhodactis species to rapidly reproduce and completely smother reefs, managers are now facing the possibility that even with removal of the ship, sheer reproductive capacity of Rhodactis howesii may continue to fuel its spread along the western reef shelf of Palmyra".

This problem could put in jeopardy many sensitive marine ecosystems but unlike the climate change it has much simpler solution, namely removing man-made debris such as shipwrecks from coral reefs in order to ensure healthy underwater ecosystems. What we really need is the "better prevent than cure" tactic where the main goal is to prevent invading species like Rhodactis howesii overtake healthy coral reefs. However, using this very simple tactic is never that simple. Especially not in ecology.

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