Trophic Cascades in Coral Reefs - Paper!

Mean density of trophic groups (±95% confidence intervals) for fished (red) and non-fished (green) reefs.

The density of trophic groups across fished, non-fished, disturbed (stippled bars) and non-disturbed (solid bars) reefs are shown. Figure 4. Mean density of trophic groups (±95% confidence intervals) for fished (red) and non-fished (green) reefs. The density of trophic groups across fished, non-fished, disturbed (stippled bars) and non-disturbed (solid bars) reefs are shown.

Finally!

This is what I've been waiting for!

This paper is simply epic - read it!

So far, the most cited example of Sharks and trophic cascades has been the controversial 2007 paper by Meyer about those exploding Cownose Rays (synopsis here). There are also Ferretti et al that I personally prefer, Sandin et al where the snapshot approach is highly questionable, and then there's a lot of anecdotal evidence that however still requires rigorous testing. All-in-all, it's a lot of interesting stuff - but so far, the findings appear far from being unequivocal, this also owing to the complexity of the investigated food webs.

This however is different.

First, it is not based on meta-analysis but instead, on original and comprehensive long term monitoring over a period of ten years which in itself is rather epic. Secondly and contrary to what happens in most other locations where people are fishing down the food chain and thus inhibiting any postulated mesopredator release, those Indonesian fishermen were selectively targeting Sharks and leaving the other Fishes more or less alone, meaning that any of the detected effects were singularly isolated.

You can read two excellent synopses here and here.

My take-away message is that contrary to more simplistic statements that the removal of Sharks will ripple down through the food chain and eventually lead to the demise of coral reefs, this paper comes to the conclusion that it is instead the presence of Sharks that may play a critical role in the recovery of coral reefs that have been previously damaged by other factors. The paper also once again confirms that due to the high level of residency of Reef Sharks, even comparatively small MPAs may be highly beneficial.

Long story short?
As it becomes all but inevitable that climate change will further damage our coral reefs, those Reef Sharks may indeed turn out to be one of our best allies in trying to mitigate those effects.

If we stop wiping them out that is.

And that is far from being a certainty!