Dive Time with Tim Grollimund

Which way will the ball bounce?

April 11, 2013 

The matrix of factors that affect reef resilience include water quality and larvae recruitment for an ecosystem to be vivacious. (Photos by Tim Grollimund)

Back in my college baseball days, a little nick, bruise or bump was not a big deal. You played through it. The ability to absorb and adapt was something we did naturally. We were resilient. Actually, we thought we were bulletproof, especially after a win, while gathered at the local pub. Not doing any studying tonight!

Contrast that to my years as an umpire later in life. I used to call about 150 games a year. Bumps and bruises hurt a little more and healed slower. Sometimes my knee was the size of a coconut. But I kept walking out on that field. The resilience was still in the mind, but not so much in the body.

How does the concept of resilience fit into the reef ecosystem? At our last Ecosystem Protection Working Group meeting, Dr. Robert van Woesik of the Florida Institute of Technology talked to us about his studies on ecosystem resilience. See his vast body of work here: http://my.fit.edu/~rvw/. Join me in a shout out to him, as he became a US Citizen on April 5.

Imagine a tennis ball suspended in a kiddie pool. That ball can shift positions all around the pool, depending on the movement of the water in the pool. Imagine the ball represents a group of fishes, corals, and invertebrates. It’s a three-dimensional matrix.

Now change the temperature, salinity and pH of the water. And add people and all of what we do in, on and around the water. A healthy ecosystem with all these variables is a pretty complicated equation. The ball moves around the pool, and with enough agitation may fall out of the pool, landing in the grass (a less desirable state).

Dr. van Woesik has important insight through his studies on how ecosystems absorb, adapt, and strive to flourish.

Let’s take a series of six patch reefs as an example. Two of those patches get nailed by some sort of coral disturbance that affects its health and vitality. The other four, upstream, are not affected. Connectivity principles suggest the healthy four patches may act as a source of replenishment for the two disturbed patches.

But there is more to the equation than that. If the disturbance is acute, then yes, the recruitment and settlement can take place and those patches will get back to a healthy state. But if the disturbance triggers a chronic condition, all the larvae in the world can pop on to the patch but health will never be regained.

Dr. van Woesik taught me a concept he calls “sources and sinks.” Sources are reefs where the larvae come from, and sinks are where they end up. We need both. Sources can be local or distant, depending on the species, the water flow and the development characteristics of the larvae. Corals can be local or distant; corals can disperse locally, or travel hundreds of miles; it all depends on the local currents.

Resilience has as much to do with sinks as it does sources. In our case, the lack of urchins over time, I think, can be viewed as a giant hole in the sink. It’s a chronic issue that drains the life out of the reef — regardless of the sources of larvae. The overabundance of algae creates a scenario for weak recruitment of coral. Can you manage a reef back to health under those conditions?

Here’s another example: lionfish, according to the science, are having an increasingly detrimental affect on key species. They eat the juvenile fishes of other fish species, and create way too many of their own juveniles for our liking. Will we eradicate lionfish? I doubt it.

Could increased protection help mitigate the lionfish effect? Can we manage the capacity of the ecosystem to absorb and adapt to the invasive species shock?

Last time we looked at connectivity principles. Today we added the resilience layer on top of connectivity, and we have an entirely new scenario. Capacity for replenishment is, literally, a new layer on the map.

Protecting sources and sinks is important. We need to protect the spawning grounds for our key species. But we also need to identify healthy sinks that will hold recruitment and provide the reef ecosystem the best chances to revive and rebuild.

According to Dr. van Woesik, “Coral bleaching, coral diseases, and ocean acidification jeopardize the natural resilience of coral reefs. Recovery, resilience, and the degree to which coral species are connected among reefs has led to discussions on the optimum size and optimal placement of marine protected areas.

Intuitively, preserving larval source reefs will be beneficial... by improving water quality, local reef resilience may be increased in the face of climate change induced thermal stress.”

None of this takes into account all the external factors we don’t control, like the quality of the new water that will be moving down from the Everglades in the near future. That’s another discussion for another day.

As we move forward with the sanctuary project, will we create the capacity in our waters to act like the young player — to absorb the nicks and lumps and still play at the highest level — or will we position the sanctuary to be the old umpire that limps around the field on swollen joints, with bruises slow to heal? I believe it’s within our reach, using the best available science, to build a resilient, connected, sustainable sanctuary.

As always, these are my thoughts, and are not the official views of the agencies with oversight of the sanctuary.

Tim Grollimund is a freelance photographer and PADI divemaster based in Key Largo. He can be reached at tim@timgimages.com or through his web site at www.timgimages.com. Tim is a member of the Ecosystem Protection Working Group for the Florida Keys National Marine Sanctuary.

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