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Gulf of California 2015, Leg 3 – Biodiversity and Biooptics – Log 1

Gulf of California 2015, Leg 3 – Biodiversity and Biooptics – Log 1

Research Goals for the Biodiversity and Biooptics Leg

The R/V Western Flyer set sail on Saturday, March 7th, at 7:00 a.m. the third leg of the MBARI 2015 Gulf of California Expedition. Led by Steve Haddock, MBARI researchers and collaborators onboard during this leg specialize in molecular studies of “gelatinous zooplankton”—jellyfish-like siphonophores and ctenophores that can dominate midwater ecosystems. Relatively recent research has brought to light the key role these animals serve in ocean ecosystems. These fragile and fascinating organisms are incredibly abundant, yet almost totally unknown. Insights into the genetic underpinnings of adaptation to extreme environments give us a window in the history of life and marine biodiversity.

Haddock and colleagues will work to:

  • Collect DNA and RNA samples for genome-scale sequencing to determine what genetic differences allow organisms to survive in deep-sea or low-oxygen environments. This information helps us understand how the animals sort themselves into their preferred microhabitat, whether based on temperature, oxygen, light levels, nutrients, competition, or predation.
  • Document the biodiversity of deep-sea animals based on ship- and lab-based identification and DNA analyses of collected specimens. Measuring the relative abundance and distribution of gulf species will provide important data that can be used to anticipate how animals have evolved to survive and even thrive in challenging environments.
  • Examine the bio-optical properties of gelatinous zooplankton to investigate the evolutionary origins and function of bioluminescence and fluorescence. Nearly all of the medusae, comb jellies, and siphonophores we have collected, not to mention the fish, squid, and shrimp have luminescent capabilities.

Some of the beautiful gelatinous zooplankton we saw on today’s dive, from top, include the siphonophores Apolemia (2,500 meters) and Erenna (1,517 meters) and the medusae Crossota (3,000 meters) and Halicreas (2,000 meters).

During the next 10 days we will sample south and central basins in the Gulf using ROV and blue-water SCUBA dives, as well as a midwater trawl net. We will compare our observations with the results from our 2012 trip to the Gulf of California as well as more than 25 years of records from Monterey Canyon. We immediately noticed striking differences during our first few dives just off of La Paz and in Farallon Basin. For example, the siphonophore Nanomia is the most common siphonophore we see in Monterey Canyon, and we haven’t seen one yet! In Farallon Basin we saw numerous delicate small white Crossota alba as we neared the muddy bottom at 3,100 meters (approximtely10,000 feet). These animals are uncommon in Monterey Bay.

Dive sites off of La Paz and in Farallon Basin.

On our ROV Doc Ricketts dive just off La Paz we managed to sample two unusual blue siphonophores at around 350 meters depth. Back in the lab they were identified by Casey Dunn as the prayid Mistoprayina fragosa, so-named because of their extremely delicate and fragile nature. In fact, the scientists who originally described this animal (Pugh & Harbison, 1987) were unable to get an image of a live, intact specimen for the description. With our high-definition camera and skilled maneuvering by the ROV pilots we were able to capture beautiful footage of this amazing animal. Another MBARI first!

In the original 1987 paper, Phil Pugh and Richard Harbison referred to a line drawing of the animal in the description: “Unfortunately, no photographs or drawings of the living specimen were made and, since it would be meaningless to illustrate the shrivelled, preserved nectophore, a reasoned reconstruction is presented here.”