Written by Lauren Steele
The Gulf of Maine is a body of water that covers 36,000 square miles and borders on the states of Maine, New Hampshire, Massachusetts as well as New Brunswick and Nova Scotia, Canada. The Gulf has deep basins, shallow banks, and powerful tides. The cold North Atlantic water mixed with the freshwater of 60 rivers that empty into it provide a nourishing environment for a huge number of marine and bird species – over 3,000. The coastal marshes provide nurseries for fish, crabs, shrimp, and shellfish to safely reproduce. An abundance of plankton and microbes anchor an important and diverse food web that includes animals as large as seals and whales. The waters of the Gulf provide sanctuary for more than 30 at risk species including the North American right whale.
This area has been a feeding ground for fish like cod for thousands of years. Cod fish had been an important food source and export product for centuries until they were recently almost overfished into extinction. It is thought that the fishing quotas for cod were set too high because the effects of climate change and warming waters were not considered. By the time people realized what was happening, it was too late. In 2015, the cod stock stood at only 4% of its optimum size. Now most of the people who live along the coasts and have relied on fishing for their livelihoods for generations have either had to switch to trapping lobsters or find another way to make a living. This has been devastating to fishing communities like Gloucester, MA. Interestingly, the lobsters have been increasing in numbers because there are fewer cod to eat them as babies.
The waters of the Gulf of Maine have been warming up as a result of global climate change more quickly than in 99% of the rest of the world. Scientists are studying what is happening to the ecosystems there, hoping to get an idea of what other areas will eventually experience in time. All the sea ice melting to the north is “freshening” the water, changing its chemical composition as well as its temperature. The salinity is being diluted by the influx of fresh water. Climate change has increased the number of storms which bring heavy rainfalls, and because of the high levels of atmospheric CO2, this is causing the water to become more acidic. Ocean water is a natural sink for CO2. The gas goes through a chemical change and becomes carbonic acid. CO2 + H2O turns into H2CO3. This is a necessary ingredient used to provide the calcium required by sea creatures who need it to build their own shells. But too much of this chemical starts to have a negative effect. The increasing acidity starts to dissolve the shells on clams, oysters, lobsters, etc. which eventually kills them.
At the bottom of the food web, phytoplankton and zooplankton have been adapting to warmer water by changing the timing, size, and composition of their seasonal blooms. This affects species of animals all the way to the top of the web. The timing is especially problematic since different animals are programmed to arrive in certain areas at certain times of year in order to take advantage of the feeding opportunities there. If they arrive too late, they could starve, not be able to reproduce, and die.
There are species of animals that are usually found farther south that are showing up in the Gulf in greater numbers. For example, there is an invasive, inedible species of crab called a “green crab” that has been dramatically increasing in numbers due to the warmer waters. They are gobbling up all of the softshell clams, oysters, and blue mussels and ruining the seagrass meadows with their aggressive digging, which are crucial habitat in estuaries. They also reproduce prolifically. There are other invasive species moving in as well. Their presence is disrupting the trophic hierarchy of ecosystems and having a negative impact all throughout the food chain right up to dolphins and whales.
Climate Change is slowing down the circulation of the ocean. The Gulf Stream is shifting northward due to the slowing down of the AMOC – Atlantic Meridional Overturning Circulation. The AMOC carries warm surface water northward and cold water, which is deeper due to its increased density, southward. It is a crucial part of the Earth’s climate system. The current is driven by the differences in the temperature and salinity of the water. The warmer water eventually works its way up into the Gulf of Maine. The slowing of the AMOC has also been associated with the recent sea level rise, since warmer water expands to take up more space.
Many people just think of the ocean as a place to go sailing or to cool off after frolicking at the beach. But the ocean is actually helping to make the Earth a much more habitable place for us. The ocean plays a vital part in regulating the temperature on Earth. It is also the only source of all the fresh water that we will ever have to drink due to its leading role in the hydrologic cycle. Photosynthesizing phytoplankton in the ocean are responsible for producing 70% of the oxygen on Earth. Scientists believe that phytoplankton levels have decreased by 40% since 1950 due to the warming ocean temperatures. The ocean provides us with a large diversity of nutritious foods and medicine. We need to look beneath the sparkling waves and consider how much we depend on the ocean for our survival as a species. But the ocean is in trouble, largely as a result of thoughtless human activities. It needs our understanding, support, and protection now more than ever, to keep it alive and functioning optimally so it can keep us alive, too.
With love for the Earth,
Sources for this article include: