Hey! The day shift is a well-oiled and syncopated machine! And, we appreciate the night shift getting to a station just before they are about to get off shift. Gives us more time to wake up. July25 was another bonus day for hypoxia lovers. From 35 m into 14 m on transect H provided low oxygen waters in the range of 0.05 to 0.1 to just below 1 mg/L. Moving west to the inshore end of transect I we continued with the mixed water column until I3 in about 17 m to start into the low oxygen waters as we moved further offshore. Hypoxia went on and on and on south along transect I. We thought we would be going to Mexico. Finally in xx m the bottom oxygen levels rose above 2 mg l-1 and we headed west to transect J.
The seas began to calm early afternoon and we are at 1 to 2 ft now.
Weu2019ve been seeing large rafts of Sargassum weed during the day when we were out of the turbid coastal current.
Box coring was finally a success at stations I3 and I4. This area had been cored between 1989 and 1997 for various projects and station I3 had an accumulation rate of 0.41 cm y-1. Box coring on transects B and C was unsuccessful, and was not attempted along transect A because the area was disturbed by Hurricane Katrina in 2005. The new cores will be split so that material for dating the core and for conducting dinoflagellate cyst analysis could be from the same horizons. Additional measurements representing indicators for increased productivity or worsening hypoxia will also be made. The dinoflagellate work will be done by a Ph.D. student, Andrea Price, from McGill University (a student of former LSU colleague, Dr. Gail Chmura).
Tonight the Nightshifters sampled many blue water stations and at each were greeted by schools of flyingfish. Until tonight we had only seen very small flyingfish, about an inch long, but tonight we saw numerous individuals ~6 inches long. We got quite the show at one station where the flying fish leapt out of the water and took flight for several feet.
In honor of our flying friends we dedicate this blog post to flyingfish. Check out the photo gallery for a flying fish photo!
There are over 50 species of flyingfish, living mainly in the tropics and subtropics. Eight of these species live in the Gulf of Mexico. Some flyingfish species are monoplanes with just one set of "wings" u2013 only their pectoral fins (just behind their head) are enlarged. Other species are biplanes with two set of "wings" u2013 both the pelvic and pectoral fins are enlarged. We have seen primarily monoplanes at our stations, with a few biplanes.
Please note here that the use of the term "wings" is more for a mental image of the fish rather than a functional description. Flyingfish do not flap their wings like birds, but instead glide through the air. To take flight, the fish accelerates to top speeds using its tailfin and as its body leaves the water, it spreads its large pectoral fins. It then gains lift using winds, or updrafts from waves. This take off process is similar to an airplane taking off as it speeds down the runway.
Flying is an important predator avoidance mechanism for the flyingfish. Flyingfish are an important food for several speedy predators including dolphin, tuna, and billfish, as well as slower predators like humans. Flyingfish are actually a delicacy in Barbados where they are the official national fish u2013 the author has dined on flyingfish in Barbados.
Flyingfish are predators themselves, feeding on small fish and crustaceans in the surface waters. They are further connected to the surface ecosystem as they lay their eggs in mats of Sargassum u2013 a type of seaweed named for its prevalence in the Sargasso Sea. We also saw lots of Sargassum at the blue water stations this evening where we saw the flyingfish.
I know an entry discussing lush life in the surface waters seems a bit odd for a blog about a cruise mapping the "Dead Zone" on the bottom. But it serves as a reminder of the delicate Gulf ecosystem and the importance of its protection. On our cruise, we seek to not only describe the extent of the Dead Zone, but also to gain a better understanding of the mechanisms behind its formation. I doing so we can learn how to better protect the Gulf as an amazing natural resource.