The concept of shifting baselines is an important one in reef ecology which basically describes how successive generations of researchers have their own ideas of what constitutes a healthy or a natural reef. Nowhere is this concept more important than on the heavily degraded reefs of the Caribbean whose coral populations were heavily degraded before they could be well documented.
For example, Acropora palmata elkhorn coral used to be so abundant that entire zones of the reef were called Palmata Zones and they were a serious hazard to ships of early explorers. Fast forward to this millenium, and there is practically no such place that has a true Palmata Zone as this species has been decimated over 99% of its range.
It’s a pity that Caribbean reefs experienced such extensive degradation at all, but also a shame that it happened before much of it could be documented so we know what has been lost. Thankfully, at least a handful of historic photographs from the 70s show how glorious Caribbean reefs used to be, with fields of corals that actually resemble and rival the dense coral growth of Indo-Pacific reefs.
These images of shallow and deeper corals reefs around Discovery Bay Jamaica by Professor Phil Dustan show fields of Elkhorn and Staghorn coral growing in close proximity, practically crowding each other. And in deeper water a similar picture is shown of possible plating Montasrea (Orbicella) annularis and luxurious stands of Agaricia.
We don’t know what is more disheartening, that these exquisite reefs have now been reduced to a rocky wasteland or that dense healthy coral reefs like these are all but completely gone from the Caribbean. We know that there are a few places left which harbor fairly healthy reefs with respectable coral cover but they don’t compare to the historic photos of these “old growth” coral reefs.
It’s not all bad news though, because we know that with a hands-on approach we can regrow the Acropora to an appreciable degree and Diadema urchins that clean the reef of algae cleaning the structure for coral colonization are making a comeback. Perhaps with closer management and by addressing various environmental issues we could see the reefs make a collective rebound but it will take at least a human generation for the baselines to shift in a positive direction. [Biosphere]