Greeting from Abaco Bahamas. I am here for a few days to help one of my grad students, Andrea Anton, who is working on lionfish which are EVERYWHERE here as they are across the Bahamas. The densities, only a few years after arriving, are truly remarkable.
But the real purpose of this post is to show some pictures of the amazing site we worked at today. It was a remote, shallow reef and easily had more fish and sharks than nearly anywhere else I have ever been. As soon as we entered the water a large school of tarpon come in to check us out. Within minutes we were being circled by four 5 ft black tip sharks. There were very large jack, barracuda, massive snapper, and incredible numbers of a variety of grouper everywhere. And ocean triggerfish seemed especially abundant. There were also plenty of Diadema and a fair number of parrotfish, surgeon fish and blue tangs, so there was little macroalgae. Many extremely large gastropods and more cyphoma that I have ever seen.
Unfortunately the coral cover was very low. In the shallows, probably < 1%, but this is a very exposed site. In deeper water, it was roughly 5-8%. But there were a lot of A. palmata colonies near the shore. And despite the low coral cover, this was without doubt a thriving and productive ecosystem. I heard an NGO head recently declare that once coral cover goes below 10%, the reef is functionally extinct and lost. I couldn’t disagree more.
The funny thing about this reef was that it isn’t in an MPA or in any way managed. No NGOs are protecting it. No scientists are studying it. And the lack of coral clearly hasn’t caused the fish community to collapse. Likewise, the presence of the fish and top predators didn’t maintain “reef resilience”, i.e., the corals still died when they bleached in 98. Funny how the real world mucks up all those cozy ideas academics dream up.
I’m jealous. Stuck in the drab, rainy Swedish autumn and dreaming of the sun and reef.
Very interesting post John, always cool with these stories that don’t follow the theoretical paradigms. Although the work by Shaun Wilson, Nick Graham and others shows that fish communities (if we exclude many of the coral obligate fish species) are remarkably resistant to live coral loss. How was the structural complexity of the site? Still, if it bleached in 98, we should expect similar patterns as in IWO, where fish communities began collapsing 5-6 yrs after bleaching (with no coral recovery). Interesting.
Any idea of the pre-bleaching coral cover? Fishing pressure?
Enjoy the sun
No, I don’t no anything about this reef, other than what I saw. Based on dead coral skeletons (in situ and on the shore) and the general setting, I assume this was a pretty typical exposed Caribbean reef, formerly dominated by Acropora.
“How was the structural complexity of the site?”
The reef, especially above 8 m, is very flat. Really a hardbottom community now. With little structure at all. I wouldn’t be surprised if the density/richness of smaller fish is low here. After all, those predators have to be eating something!
“Still, if it bleached in 98, we should expect similar patterns as in IWO, where fish communities began collapsing 5-6 yrs after bleaching (with no coral recovery).”
Good point. And I actually dont know whether the coral collapsed in 98 or in the 80s due to white band disease.
“Any idea of the pre-bleaching coral cover? Fishing pressure?”
Fishing pressure is minimal even though there is a small town within a few kms. The locals have a very lucrative alternative source of income (hint; they have their own runway). And the ones we talked to are scared shitless of the sharks. They seem to have lost the fishing tradition locally. Certainly requires further study!
Wonderful photos, John. I hope Andrea research gives us some better insight as to why these invaders have been so successful in that region of the Caribbean.
Its interesting that you mention the abundance of fish despite the lack of coral cover and reef complexity. I came across a relevant article recently which investigates declines in coral cover on the GBR to coral mortality events (ie. bleaching). Apparently, the study reveals on only a short-term impact of coral mortality event on the diversity of coral reef fishes, not long term. Fish diversity return to the reefs actually returned! However, the article does no record observed fundamental changes in the community structure of fishes. So i would be interested to know what the diversity of fish were like at the site…
Here is the article if you are interested: Wilson, S. K., A. M. Dolman, et al. (2009). “Maintenance of fish diversity on disturbed coral reefs.” Coral Reefs 28(1): 3-14
Just a quick clarification – the article above does show fundamental changes in the community structure of ﬁshes (shifts from corallivores – herbivores), even if the short-term impact on fish diversity is limited (assuming the reef framework is intact).
Thanks for the clarification. You’re 100% right.