Tuesday: June 11, 2013
Log Day 10

Dr. Peter Auster
Research Professor Emeritus
   University of Connecticut
Senior Research Scientist
   Mystic Aquarium -
   Sea Research Foundation

Carolina hake in 'snow storm'. (Photo: Peter Auster)

Like Trying to Study the Behavior of Eagles and Hawks in a Thick Fog.

So my band of merry divers is focused on quantifying the behavioral interactions within and between groups of fish predators and their prey. This year our goal is to understand if the web of such interactions is different inside and outside of the Research Area where fishing is prohibited. I often describe this work as similar to that of ecologists studying birds of prey on land where they revisit sites inside and outside protected forests or meadows and collect data when predators seek out prey.

Loggerhead sea turtle. (Photo:Peter Auster)

Generally, such studies requiring direct observations avoid days of thick fog or rain and snow. Underwater such a study requires significant visibility, normally seeing 15 ft or more does the trick, and this is generally status quo here at GRNMS. Enter Tropical Storm Andrea. She blew through with sustained winds to 40 mph and gusts to 53 mph as measured at the Gray's Reef Data Buoy. Waves and swell peaked at more than 12 ft. During and after the storm runoff from all the rain on land spread across the shallow shelf. All of this is a recipe for conditions underwater resembling a thick fog on land.

Cubby and cardinalfish in 'snow storm'. (Photo:Peter Auster)

We had visited six of our study sites prior to the storm and conditions were fine. We saw barracuda and greater amberjack chasing and attacking prey such as juvenile scup with seafloor predators like black sea bass attacking from below. Two days after the storm, when winds and sea subsided, we tried to get back to work. Nearly zero visibility on the first dive cut our time underwater to a short four minute dive. Today was better, with 10 ft on the first dive in the morning. Unfortunately the fog rolled in as visibility on subsequent dives ramped down to eight and then less than 5 feet as wind and waves increased just a bit on the surface.

Lionfish and long-spined urchin. (Photo:Peter Auster)

Interestingly, and despite the poor visibility, we learned, or think we learned, some new things. For example, some species like Carolina hake and cardinal fish remain in their shelters, despite severe changes in their ability to see prey and predators. Do their lateral line systems make up for loss of sight ability? Other predator species like greater amberjack and Almaco jacks may form smaller groups when attacking prey and visibility is limited. Is this pattern real - we need more data - but if true suggests that vision is important for group cohesion and coordination and loss of visibility may affect feeding rates. Even dives that may not be that useful for our primary study reveal new and interesting ways to think about how the ocean world functions, and always more to come.