DMR Lobster Settlement Survey Dives

I spent Friday Oct 18 and Monday Oct 21 helping (by sorting samples) DMR scientists Robert Russell and Carl Wilson, who are conducting their annual dive survey of larval lobster settlement rates at 50 sites along the Maine coast. At each site they sampled 12 quadrats via underwater suction sampling. Samples were then sorted and processed on the boat. The suction sampler pulls up all loose sediment and other organisms, so we needed to sift through it and pull out any lobsters and crabs we found. Many of the samples also had shrimp, urchins, seaweed, brittle stars, marine worms, asst. shells, and occasionally rock gunnels and cunner (fish). Once the sample was sifted, we measured the lobsters and crabs carapace length, and we also collected data about the lobster's sex and number of claws.

The boat they used for these dives was the 38' Lady Anne, operated by Sea Ventures Charters, Captained by Dave Sinclair.

Some of the sites we visited during these surveys were Head Harbor at Isle Au Haut, Ragged Island, Allen Island, Matinicus, Hurricane, and Monhegan

Overall, Carl and Robert said that they were seeing far fewer settler-size lobsters across all of their sites than in previous years (this survey has been going on for 22 years). For example, we only found 6 settlers from the 5 sites that were surveyed on Friday, when in the past Robert and Carl have found 4-5 settlers per site in that area.

The data from these surveys will feed into the American Lobster Settlement Index.

Northern Flicker

For the past month and a half there have been many Northern Flickers and other woodpeckers flying quietly around Hurricane. Mostly I have only noticed them after they have been spooked and are flying away, but the underside of their wings is an unmistakable yellow that is visible even from far away. The Yellow-Shafted Northern Flicker Colaptes auratus is a unique woodpecker because it is actually often found foraging on the ground or perched upright on trees rather than against the trunk like their woodpecker relatives. Unfortunately, we found a beautiful female dead on Hurricane last week, likely from hitting a window.

Learn more about Northern Flickers at the Cornell Lab of Ornithology. 

Hurricane Geology

Last weekend Bowdoin undergraduate students came to Hurricane, and I tagged along as they toured the different pocket beaches around the island. Although all of Hurricane's bedrock geology is granite, there are other types of (mostly igneous) rocks found on the island that traveled over from Vinalhaven and North Haven when the whole region was covered by a large glacier. Glacial till is characteristic because it is unsorted, which means that there are several different clast sizes and many rock types. The Flow-banded rhyolite, pictured below, was found in a pocket beach just east of Gibbon's Point. Flow-banded rhyolite is chemically equivalent to granite, in that it has high amounts of potassium and silica, but it formed in very different conditions. 

A professor holds out small clasts of Flow Banded Rhyolite,  

Hurricane's Hummingbirds

I first started noticing these ruby-throated hummingbirds (Archilochus colubris) feeding on a large patch of jewelweed (Impatiens capensis) in early September. This species of hummingbird beats its wings about 53 times a second and weighs between 2-6 grams (for comparison, 2 nickels weigh 10 grams). You can read more about hummingbirds here.

Check out this computer simulation of a hummingbird in flight, the red indicates vortices of air. Haoxiang Luo, a professor of mechanical engineering at Vanderbilt, built this simulation from slow motion videos of the hummingbirds flying. This cool science blog from NPR talks more about this simulation and how hummingbirds fly.

Tracking Lobster Movement Through Traps

Lizzie's GoPro setup

Lizzie Morris, an undergraduate student majoring in neuroscience at Middlebury College, stepped out of the traditional bounds of her major and dove headfirst into the world of lobsters as our inaugural summer intern on Hurricane. Using our demonstration lobster traps, Lizzie captured and marked both sublegal- and legal-size lobsters and staged them in a monitoring trap rigged with GoPro video cameras in order to track their movement and intraspecies trap dynamics over a two-hour deployment off Hurricane’s pier. Lizzie poured over hours of video footage and found that there was a lot of trap traffic-- a surprisingly high number of lobsters (both sublegal- and legal-size) staged in each test round were able to escape the traps within two hours. Two hours was also enough time to attract new entrants, mostly sublegal females. Her summer concluded with more questions and possible avenues for this experiment, and we are excited to turn this pilot study into a longer-term project that involves our participants in the future!