Happy April Fools! Guests aboard National Geographic Explorer woke up in route to Rio de Janeiro. With sleepy eyes and morning coffee, guests listened as expedition leader Jim Kelley told them there would be a lecture at 9 a.m., and then a lecture at 10 a.m., and then yet another lecture at 11 a.m.; on napkin folding, no less. Some muttered and some snickered, and soon all realized it was just an April Fool’s Day prank.
Our morning lectures did begin at 10 a.m. with Eduardo Shaw, speaking on a certain historical hero of Uruguay, Argentina, and Brazil. When his historical talk was finished, most people gathered on the outdoor areas to enjoy the fantastic 73 degree weather, where sun abounds. After lunch oceanographer Deb Goodwin took a plankton tow, a system of ocean sampling that uses a fine mesh net to concentrate the plankton community into a bottle attached at the bottom of the net’s funnel. The natural history staff have been collecting samples as the journey progresses, tracking the difference in pH, salinity, temperature, and species diversity. All of these factors are very closely linked. As ocean temperatures drop, the water becomes denser and can more easily bond to oxygen. With denser, oxygen-rich water, a larger community of planktonic life can be supported. This plankton community is also enhanced by sunlight, which has been prolific in the Southern Ocean (as we are just entering the southern fall). As the ship moves further north the temperature of the water warms. The warmer water is less dense and the molecules are more excited, making it more difficult for them to happily bond to oxygen and thus decreasing the plankton load this part of ocean can carry. Each tow the natural history staff takes shows this difference and change in real-time. As we continue into the warmer waters the guests should continue to find a decrease in overall plankton density and also in diversity of species within the plankton community.
When the ocean sampling was over, a beautiful evening emerged. Hotel Manager Patrik offered appetizers and delicious libations on the back deck as the guests enjoyed watching the sunset on their first true tropical evening aboard.
