NOAA Teacher at Sea
Aboard NOAA Ship Oregon II
June 22 – July 6, 2017
Mission: SEAMAP Groundfish Survey
Geographic Area of Cruise: Gulf of Mexico
Date: July 20, 2017
Weather Data from the Bridge: I am now back in Longmont, Colorado
Latitude: 40 08.07 N
Longitude: 105 08.56 W
Air temp: 31.1 C
Science and Technology Log
One of the major questions I had before my Teacher at Sea voyage was how the level of oxygen in the water will affect the species we collect. Typically, in the summer, a dead zone forms in the Gulf of Mexico spreading out from the mouth of the Mississippi river. You can see an image of the dead zone from 2011 below.
Phytoplankton, or microscopic marine algae, are the base of the marine food web. There are two main classes, diatoms and dinoflagellates, which are both photosynthetic and typically live towards the top of the water column. We did not sample plankton on our leg of the cruise, but if you want to learn more you can check out this site: https://oceanservice.noaa.gov/facts/phyto.html. In the summer, phytoplankton and algae can build up due to excess nutrients in the water that are running off from urban areas, agriculture and industry. Much of our sampling was near the mouth of the Mississippi River, which is a significant source of excess nutrients. The extra nitrogen and phosphorus in the runoff cause the excess growth of photosynthetic organisms which leads to a buildup of zooplankton (heterotrophic plankton). Once the phytoplankton and zooplankton die and sink to the bottom they are decomposed by oxygen consuming bacteria which deplete the oxygen in the water column. According to NOAA, hypoxia in aquatic systems refers to an area where the dissolved oxygen concentration is below 2 mg/L. At this point, most organisms become physiologically stressed and cannot survive.
Tropical Storm Cindy, which kicked up just as I was arriving in Galveston, brought significant freshwater into the gulf and mixed that water around so we did not see as many low oxygen readings as expected. While I was talking with Andre about hypoxia when we were on the ship, he used the analogy of stirring a bowl of soup. There is a cool layer on top, but as you stir the top layer and mix it with the lower layers, the whole bowl cools. Similarly, the oxygen rich freshwater from the storm is mixed around with the existing water, reducing the areas of low oxygen. You can see in the map below that we had fewer hypoxic areas than in 2011.
We used the CTD to obtain oxygen readings in the water column at each station. In the visuals below you can see a CTD indicating high oxygen levels and a CTD indicating lower, hypoxic, oxygen levels. The low oxygen CTD was from leg one of the survey. It corresponds with the red area in the hypoxia map above.
Personal Log and Reflections
When I arrived back on land I still felt the rocking of the Oregon II. It took two to three days before I felt stable again. As friends and family ask about my experience, I find it hard to put into words. I am so grateful to the NOAA Teacher at Sea program for giving me this incredible experience and especially thankful to Science Field Party Chief Andre Debose and my day shift science team members, Tyler, David and Sarah, for teaching me so much, being patient and making my experience one that I will never forget.
The ocean is so vast and we have explored so little of it, but now, I have a strong understanding of how a large scale marine survey is conducted. Being an active participant in fisheries research was definitely out of my comfort zone. The experience helped stretch me and my learning and has giving me great insight to bring back to share with my students and school community. The map below shows our journey over the two weeks I was on the ship traveling along the Texas, Louisiana, Mississippi and Florida coasts.
My experience on Oregon II has also re-engaged me with the ocean. As a child, I spent time each summer on an island off the coast of Maine and even got to go fishing with my Dad and his lobsterman buddies. But for the last 20 years or so, my exposure to the ocean has been limited to just a few visits. My curiosity for the marine world has been reignited; I look forward to bringing more fisheries science and insight into my classroom.
I mentioned in a previous blog that our shrimp data was sent daily to SEAMAP and made available to fisheries managers and shrimpers to allow them to make the best decisions about when to re-open the shrimp season. According to Texas Parks and Wildlife (TPWD), the commercial shrimp season for both the state and federal waters re-opened just after sunset on July 15, 2017. TPWD said, “The opening date is based on an evaluation of the biological, social and economic impact to maximize the benefits to the industry and the public.” It is satisfying to know that I was part of the “biological evaluation” to which they refer.
Finally, I took some video while out at sea and now with more bandwidth and time, I’ve been able to process some of that video to shed additional light on how fisheries research is conducted. I’ve added two videos. The first one shows the process of conducting a bottom trawl and the second one show the fish sorting and measuring process. Enjoy!
Did You Know?
You can use the following sites to help you make smart sustainable seafood choices:
Monterey Bay Aquarium (http://www.seafoodwatch.org). There is also a free app you can put on your phone so you can do a quick look up when you are at a restaurant, the grocery or a fish market.
The largest Gulf of Mexico dead zone recorded was in 2002, encompassing 8,497 square miles. The smallest recorded dead zone measured 15 square miles in 1988. The average size of the dead zone from 2010-2015 was about 5,500 square miles, nearly three times the 1,900 square mile goal set by the Hypoxia Task Force in 2001 and reaffirmed in 2008.
Dawson Sixth Grade Queries
Thank you to the Dawson sixth graders (now seventh graders!) for your great questions. I look forward to speaking with you all when school starts in a few weeks.
What is at the bottom of the low oxygen part of the ocean? (Allison)
There is a lot of accumulated dead organic matter that is decomposed by oxygen consuming bacteria.
What do you find in the dead zone? Do less animals live there? (Leeham, Mae, Shane, Alfie, Bennett)
Typically, trawls are smaller and the diversity of organisms decreases in the low oxygen areas. Often you will find resilient organisms like croaker. There is a lot of research looking at which organisms can live in dead zones and how these organisms compensate for the low levels of oxygen.
Is there any way to fix the dead zone? What can we do about the dead zone? (Isaac, Owen, Ava)
It is estimated that seventy percent of the excess nitrogen and phosphorus that runs off into the Gulf of Mexico comes from industrial agriculture. Reducing the amount of fertilizer used to grow our food would help decrease the extent of the dead zone area. Perhaps one of you will come up with a way to feed our communities in a more sustainable way or a technology that can remove these excess nutrients before the water reaches the Gulf.
Thanks for reading my blog!