Plankton Decline

Phytoplankton – microscopic organisms that form the foundation of the oceanic food chain – account for approximately half the production of organic matter on Earth.

Through satellite imagery, researchers have established that phytoplankton concentrations have been declining at an alarming rate since the 1950s. A combination of ocean transparency measurements and in situ chlorophyll observations has allowed scientists to estimate the time dependence of phytoplankton biomass at local, regional and global levels. In eight out of ten ocean regions, declines have been observed. A global rate of decline of more than one percent of the global median per year is projected. The fluctuations in phytoplankton levels are believed to closely correlate with climate changes and the ongoing rise in sea surface temperatures.

The Earth’s oceans are warming. Scientists have demonstrated how rising ocean temperatures and carbon dioxide levels can stress marine life. A new model developed by the Massachusetts Institute of Technology Program in Atmospheres, Oceans and Climate reveals that if global temperature trends continue, by the end of this century, half the population of phytoplankton that existed in any given ocean at the beginning of the century will have disappeared. “That’s going to have impacts up the food chain,” says Stephanie Dutkiewicz, principal research scientist at MIT.

Tiny phytoplankton, the major food source for fish and other sea creatures, could perish as temperatures rise. The organisms in the coldest waters are at the greatest risk. Researchers believe that phytoplankton could evolve to alter their body chemistry or migrate, but such a change could mean that species higher up the food chain will be unable to feed themselves.

At higher latitudes, higher temperatures and less mixing could force phytoplankton to stay closer to the surface. More sunlight in that top layer may result in changes in the mix of microorganisms, once again affecting the creatures that eat phytoplankton. Researchers believe that this warming – along with other factors such as changing levels of nitrogen and iron and ocean acidification – is also affecting the phytoplankton.

In the summer of 2008 – as the young salmon swam to their ocean feeding grounds – a volcano erupted in the Aleutian Islands of Alaska. For a few days, the erupting volcano spewed a vast cloud of volcanic ash into the air. Airline flights were re-routed and cancelled due to this thick cloud of volcanic ash. As the ash drifted in the wind it blanketed much of the Gulf of Alaska. Just a few days later ocean-observing satellites reported the largest plankton bloom ever seen from space. It would appear that the young salmon of 2008 arrived to this plankton feast, survived in great numbers, and gained strength and endurance to continue the ocean cycle of their life. If there were questions that the fortuitous volcanic dust was responsible for the apparent cause and effect benefit to the sockeye salmon, one only needs to look to the second largest sockeye salmon return in history. That second largest run occurred in the 1958 sockeye return, which followed two years on the heel of another rare Aleutian volcanic eruption.

This natural process was first proposed by oceanographer John Martin in 1993 who suggested that micro nutrient replenishment in the ocean could increase plankton levels. Over 13 experiments in the last 20 years have shown that depositing iron in high-chlorophyll, low-nutrient areas of the ocean may be a practical and cost-effective methodology for stimulating plankton growth – and thus increasing the amount of food available to organisms in the ocean ecosystem.

A recent ocean fertilization experiment conducted by the Alfred Wegener Institute in 2009 showed that no harmful environmental effects were noted in creating an artificially generated iron-induced plankton bloom.

The Haida Salmon Restoration Project of 2012 went a step further and created a large plankton bloom right in the middle of salmon migration routes, resulting in record salmon runs in 2013 and 2014.

Oceaneos conducts research, develops technology and executes micronutrient replenishment projects in specific low-nutrient areas of the ocean, in collaboration with governments and universities – with the goal of replenishing collapsing fish stock and restoring ocean life.