Galapagos: Week 2

Surveying subtidal rock walls

Leslie and I mark our first two weeks in the Galapagos with our return from a five-day research cruise around the central archipelago. We've been working with our faculty mentor Jon Witman, and two research divers from the marine laboratory (BIOMAR) at the Darwin research station - a research team of five.

Boat time is expensive and every day, every dive is a rush to collect as much data as possible. We start our first dive around 7am and do 3-4 dives till just before 5pm, when it gets too dark underwater (sunset is just after 6pm). On any one dive, we have at least five of seven things going on:

1. Photography of square plots at fixed intervals along a permanent transect. These plots have been monitored biannually for about 10 years and the photographs allow us to track changes in the ecological community on the wall over time.
2. Counting sea urchin abundance along the same permanent transect. Urchins are important grazers in the Galapagos and changes in their abundance may reflect changes in grazing rates, as well as rates of predation on them.
3. Quantifying the abundance of small sea urchins in rock and rubble habitat. These abundances reflect the rate that urchin larvae are supplied to these habitats and metamorphose into adults.
4. Recording coral species and bleaching along transects. This monitoring tracks the health of the coral community over time (and over temperature changes associated with the El Nino Southern Oscillation), which is important because corals provide habitat and food for many animals in the Galapagos.
5. Counting seastar abundance along the permanent transect. Seastars can be important grazers and predators and similar to urchins, changes in their abundance can reflect changes in grazing and predation processes.
6. Recording the sizes and feeding activity of seastars. I am collecting these as preliminary data for underwater experiments to quantify the effects of predatory seastars on urchins.
7. Recording the sizes and feeding activity of Hexaplex snails. Hexaplex are important predators of barnacles, which make up a large component of the ecological community. Leslie is collecting this information to model changes in Hexaplex abundances in areas where it is commercially fished compared to areas where fishing is not allowed.

It is a pretty full list, and diving in the Galapagos can be very challenging - we encountered some strong swells over the first few days that carried us up and down the rock walls we were working at, spinning us around like a washing machine. We've also had our share of equipment failures - flooded and stuck cameras, loose SCUBA tanks, etc. But as a whole, it was an extremely productive trip and we have plenty of data to compile and analyze before we plan our next trip out.

 

298 A rock wall at one of our research sites, showing how diverse the ecological community is.