Science

What Single-Celled Diatoms Know That We Can’t Seem To Take Seriously

Phytoplankton, such as this diatom, are photosynthesizing organisms at the base of the marine food chain (Photo Credit: UC Berkeley)

A recent scientific article from four Maine ocean scientists reminded me of a not-very-good environmental joke. An archangel was reporting to God all the terrible things that humans had done to the earth’s environment. God listened patiently as the list expanded, interjecting regularly that the archangel was not to worry; these events had all been anticipated. But when the angel reported that there was now a hole in the ozone layer, God bolted upright in shock: “I told them not to mess with the ozone layer!”

The article I was reading was not about ozone holes. Obscurely titled Step-changes in the physical, chemical and biological characteristics of the Gulf of Maine, as documented by the GNATS times series, four researchers, led by Dr. William M. Balch from the prestigious Bigelow Laboratory for Ocean Sciences, reported on work they had done looking at a number of data bases of various physical, chemical, and biological markers in the Gulf of Maine. They focused on a series of ship-based sampling data collected between 1998 and 2010.

The researchers reported a startling fact: “[t]he standing stock of phytoplankton … generally decreased since 2005” and there had been a “dramatic” decrease in carbon fixation by phytoplankton across the Gulf of Maine in recent years.

The paper explained this dramatic decrease by pointing to increased precipitation in the Gulf of Maine watersheds in recent years. Four of the eight highest annual precipitation years in the last century in Maine occurred between 1998 and 2010. The data led them to conclude that this increased and atypical precipitation—a commonly predicted phenomenon associated with climate change –interfered with phytoplankton production by discharging increased amounts of colored dissolved organic matter from the watersheds into the Gulf that outcompeted marine plankton for available light.

This is no small matter. Phytoplankton is the base of virtually all marine life in the ocean. Moreover, marine phytoplankton around the world has been estimated to draw more carbon dioxide—a primary climate change gas—from the atmosphere and the oceans than all land plants combined. The punch line to the joke might just as well have been: “I told them not to mess with the phytoplankton!”

While it will take some time before a decline in phytoplankton production in the Gulf of Maine would manifest itself higher up in the marine food web by fewer numbers of high level fishes, the Bigelow researchers were correct to point out that historic high fish productivity in the Gulf of Maine marine system is directly linked to its high productivity of plankton. The health of the marine food web depends on the strength of its planktonic base.

This report’s startling analysis aligns in a troubling way with anecdotal information from fishermen and from fisheries science data that has been surfacing recently. Fish don’t seem to be as large at the different ages as they used to be and a number of predicted strong larval year classes of fish like Atlantic cod have “disappeared” before they became big enough to enter the fishery. Are Gulf of Maine fish failing to thrive like they once did as a consequence of declines in plankton production?

Climate change is happening and its impacts are already being registered in New England. The consequences of our profligate carbon consumption patterns will continue to challenge our ecosystem, our economy, and our way of life through both dramatic and random events that devastate coastal areas as well as chronic ecosystem changes that can be seen at the level of a single-celled phytoplankton. Sadly, it’s no joke.


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