NOAA Teacher at Sea
Mary Anne Pella-Donnelly
Onboard NOAA Ship David Jordan Starr
September 8-22, 2008
Mission: Leatherback Use of Temperate Habitats (LUTH) Survey
Geographical Area: Pacific Ocean –San Francisco to San Diego
Date: September 17, 2008
Weather Data from the Bridge
Latitude: 3614.8661 W Longitude: 12402.7415 N
Wind Direction: 190 (compass reading) SW
Wind Speed: 2.1 knots
Surface Temperature: 15.230
Science and Technology Log
Above is a spreadsheet of some of the Chrysaora fuscescens data that was collected on September 15. The first trawl was at 4:48 pm, the second at 6:39 pm and the third at 8:20 pm. A fourth trawl was deployed at 10:49 pm. A total of 204 jellies were sorted and measured. Of these, the first 7jellies measured from trawl numbers’ 46, 47 and 48 are recorded above. All of the species in this data set are Chrysaora fuscescens. Using the spreadsheet, create a graph that compares mass to length for these 21 animals. When you believe you have completed this, answer the questions listed below.
- Is your graph complete?
- Check to see if you have included; all units-mass in kilograms, length in millimeters; a legend that includes the code of the points; title for each axis(length of jelly in millimeters, mass of jelly in kilograms); title for graph.
- Did you make a scatter plot, bar graph or line graph? The best choice would be a scatter plot, this may give an indication of patterns in the relationship between length and mass.
- Can you see any pattern? Is there a relationship between mass and length? This would be indicated by a linear pattern in the points?
- Do there appear to be any points that do not fit a general pattern? What might cause these points that do not fit the norm to exist?
- Compare your graph with the one shown below, generated by the computer.
These Chrysaora fuscescens were caught in “jelly lane”, in the waters near Pacifica, CA that are known to have large jelly populations. It is also an area known for leatherback sightings because of this food source. A great deal of information is known about the oceanographic conditions in this near-shore habitat. The reason the LUTH survey is crisscrossing off the continental shelf, is that much less is known about deeper offshore waters as a potential food source for migrating leatherbacks. The routes they travel on must have some food available, so we are working to find out where that is, and gain information about relationships to oceanographic variables so that researchers will be able to eventually estimate where that food is using satellite images that will be translated into jellyfish habitat.
There was quite a bit of excitement today up on the flying bridge. Although we were traveling out beyond the continental shelf, we moved over a front of water that had an abundance of moon jellies. It was unexpected and the scientific team became very excited. New plans were made based on this observation and a decision was made to cross back across the front and collect temperature data within the water column every 10 minutes. Quantitative observations were made of all jellies seen port and starboard and a net trawl was deployed at one point along the zone of interest. It was quite a day. We also spotted blue sharks, ocean sunfish, and a swordfish jumping. It was a good day.
Animals Seen Today
- Sooty shearwater Puffinus griseus
- Sea nettle jellies Chrysaora fuscescens
- Moon jellies Aurelia aurita
- Northern Fur seal Callorhinus ursinus
- Elephant seal Mirounga angustirostris
- Swordfish Xiphias gladius
- Blue shark Prionace glauca
- Buller’s shearwater Puffinus bulleri
- Ocean sunfish Mola mola
- Rhinoceros auklet Cererhinca monocerata
- Black-footed Albatross
- Phoebastria nigripes
Questions of the Day
- What might be possible reasons the scientific team was excited at finding jellyfish out beyond the continental shelf?
- The weather has been very calm and mostly overcast. One of the officers told me he would much rather have those conditions, than windy and sunny. What effect might wind have on a sturdy, ocean-going ship?