Connected!

Have you read Predators as Prey?
If not, download it now!

Here's another very actual example from the Caribbean.

Sharks, barracuda and other large predatory fishes disappear on Caribbean coral reefs as human populations rise, endangering the region's marine food web and ultimately its reefs and fisheries, according to a sweeping study by researcher Chris Stallings of The Florida State University Coastal and Marine Laboratory.

“I examined 20 species of predators, including sharks, groupers, snappers, jacks, trumpetfish and barracuda, from 22 Caribbean nations,” said Stallings, a postdoctoral associate at the FSU Coastal and Marine Laboratory. “I found that nations with more people have reefs with far fewer large fish because as the number of people increases, so does demand for seafood. Fishermen typically go after the biggest fish first, but shift to smaller species once the bigger ones become depleted. In some areas with large human populations, my study revealed that only a few small predatory fish remain.”

“Large predatory fish such as groupers and sharks are vitally important in marine food webs,” Stallings said. “However, predicting the consequence of their loss is difficult because of the complexity of predator-prey interactions. You can't replace a 10-foot shark with a one-foot grouper and expect there to be no effect on reef communities. Shifts in abundance to smaller predators could therefore have surprising and unanticipated effects."

Surprising indeed!
Did you read the post over at Shark Diver about the Lionfish invasion of the Caribbean?
It proposed that one should start marketing them as food, a suggestion that ties in beautifully with centuries of Southern French cuisine where any self-respecting bouillabaisse contains a generous helping of delicious rascasse, or Mediterranean Scorpionfish.

Here's what the original paper (read it!) says.

Predicting the ecological consequences of changes to the structure of predator communities is difficult. Different sized predatory fishes may perform various functional roles and can have drastically different effects on the diversity and abundance of prey species. Furthermore, loss of functional roles can lead to decreased ecological stability and ecosystems can become both less resilient to catastrophic phenomena such as cyclones and less resistant to invasions by exotic species.

The recent invasion of Indo-Pacific lionfishes (Pterois volitans and P. miles) in the Caribbean may have been facilitated by overfishing large predators capable of controlling their rapid spread and population explosion and is alarming considering the strong predatory effects lionfish can have on native fishes.
Management of human impacts on entire functional groups may therefore be more important than targeting specific taxa but tests of functional redundancy among predatory marine fishes is sorely needed. In addition, incorporating the effects of environmental variation, multiple human stressors, and linkages in interaction webs with socioeconomic factors that lead to overfishing may improve management and conservation in coral reef systems.

There you have it: everything is connected.
Next time anybody asks you, tell them 'bout the Lionfish!