Penn StateNASA

Module 7: Ocean Acidification, Red Tides, and Monster Jellyfish


There is one definite advantage of being over the age of forty. If you were lucky enough as a kid, you had the opportunity to snorkel or dive in a place like the Florida Keys or the Bahamas when coral reefs were healthy and diverse, colorful and teaming with life. There are very few places on Earth where this is the case today. Tragically, the large majority of reefs are in a profound state of decline, with limited growth of new coral, and overgrowth by slimy green or brown films of algae. Piles of coral debris are commonplace. The water is often muddy and the plethora of life has departed. Reefs are no longer magical places. There is absolutely no argument about it, the decline in coral reefs is human inflicted. To this point, the largest culprit is probably pollution, but that will change in coming decades. Enter Ocean Acidification, a process that has already begun, tied to our excessive CO2 emissions, and one that will accelerate soon. Corals cannot grow once the pH drops below a certain level, and if we don't act fast, that level will approach by mid-century. Reefs have survived the two largest mass extinctions the Earth has faced, but they may not survive the mass extinction humans are causing.

Ecosystems such as reefs are governed by a delicate balance of interactions between animals and plants. Yin and yang. If that balance is upset even slightly and one part of the ecosystem is favored at the expense of others, havoc can break out. The recent surge in harmful algal blooms along many coasts and the outbreaks of massive jellyfish in the western Pacific Ocean are signals of Yin or Yang, but not both. Our oceans are getting out of whack.

In the latter part of Module 6, we learned about changes in circulation and health of the oceans that are predicted to occur with climate change. In this module and Modules 8-11, we continue to address the impacts of climate change on natural systems. These changes are very much central to the issue of sustainability of the planet and its populations. "Sustainability" has a variety of definitions, and, in particular, the meaning for environmentalists is substantially different from the meaning for businesses. Regardless of where you might be coming from, sustainability means the preservation of society and our way of life. Most directly, we are concerned with maintaining the needs of people today and in the future, and this very much hinges as we will see in this module, on sustaining the life support systems of the planet.

Global warming and an array of environmental changes resulting from human activities are already causing profound impacts on organisms across the spectrum of the marine food chain. Warming of the ocean and subtle changes in its chemistry are combining with pollution and over fishing to alter the habitat of many marine creatures. In the near future, these habitats look to be further impacted, and potentially destroyed, with possibly devastating biological and economic consequences, including very negative impacts to people. The goal this module is to learn about three very different but equally significant impacts of climate change and human activity on life in the ocean: ocean acidification, red tides and blooms of jellyfish.

To set the stage, watch the Award Winning video Sea Change produced by Craig Welch: