A perfect storm is ravaging the local ocean environment.
Severe natural disasters are often associated with dramatic scenes and visible chaos: raging fires, crumbling streets or even flying debris. However, a much quieter, but potentially more long-lasting natural disaster has been festering along the Sonoma County coast in the depths of the Pacific.
Greenhouse gas emissions, the human-caused engine of climate change, warm the Earth’s surface by trapping heat in the atmosphere, and the oceans are not immune from the impact. In fact, the vast majority of that trapped heat is absorbed by the oceans, and they are reaching their limit.
Local researchers and marine biologists at the Bodega Marine Lab and the Monterey Bay Aquarium are now trying to explain how we got here and how to address the significantly altered coastline where lush kelp forests once thrived and myriad species lived and mingled symbiotically.
According to the California Department of Fish and Wildlife, “Northern California kelp forests have been reduced to an all-time low due to a ‘perfect storm’ of large scale ecological impacts.”
The main factors in this perfect storm causing this disaster are an increase in water temperature, ocean acidification and rising sea levels, with one issue feeding into the other.
These environmental stress factors ultimately lead to more frequent algae blooms and more die offs in marine life such as sea stars, the natural predator of the purple sea urchin. With more sea urchins living due to the lack of sea stars, more kelp is consumed and more dominos that affect the kelp forest start to fall.
Warming water temperatures
According to the California Office of Environmental and Health Hazard Assessment (OEHHA), “about 90% of the Earth’s increased heat energy over the last 50 years has accumulated in the oceans. Globally, the transfer of heat from the atmosphere to the oceans has resulted in warming to depths of 3,000 meters over the past several decades. Ocean warming can disrupt marine ecosystems. It affects fisheries and other commercially important sectors in California that rely on marine productivity.”
The OEHHA has sensors placed in three locations along the coast — La Jolla, Pacific Grove and Trinidad Bay — and those sensors show that “sea surface temperature increased at the rate of 0.2 degrees Fahrenheit per decade at Pacific Grove (between 1920 and 2014) and at La Jolla (between 1917 and 2016). Since 1973, however, warming at La Jolla occurred at a faster rate of 0.6 degrees per decade. At Trinidad Bay, sea surface temperatures increased at the rate of 0.4 degrees per decade over the same shorter time period (1973-2016).”
According to the OEHHA, some of the effects seen along the California coastline include influencing the timing of key life stages such as breeding, development of egg to larvae and migration; changing the abundance of prey, predators, parasites and competitors; initiating toxic algal blooms; shifting the distribution of marine species; and altering ocean mixing patterns wherein warming increases stratification between layers of warmer and cooler seawater. Stratification reduces the normal mixing across layers of seawater — a process that transports nutrients, oxygen, carbon, plankton and other material that support the marine ecosystem.
In a study from Rutgers University published in the journal Nature, scientists found that warming temperatures have a more significant impact on marine species than terrestrial ones.
According to the study, the scientists calculated "thermal safety margins" for 88 marine and 318 terrestrial species, determining how much warming they can tolerate and how much exposure they have to those heat thresholds.
“At the warm edges of the marine species' ranges, the study found, more than half had disappeared from historical territory as a result of warming. The rate for these local extinctions is twice that seen on land.”
Even just a degree or half-degree boost, the study found, can lead to trouble finding food, reproducing and other devastating effects. While some species will be able to migrate to new territory, others — coral and sea anemones, for example — can't move and will simply go extinct.
According to a study from OEHHA, during the 2014-15 marine heat wave, a variety of marine animals including fish, sea turtles and red crabs were found in waters farther north than their usual distribution. Mass strandings of some marine mammals and sea birds also occurred.
Locally, some temperature change can be normally expected, according to Andre Boustany, principal fisheries investigator at the Monterey Bay Aquarium, but recent years have seen wild swings in normally more predictable patterns.
“(The) El Niño (weather event) is fairly frequent but there are some indicators that those are becoming more frequent likely due to climate change,” Boustany said.
He noted that the El Niño event, which is a warming of waters in the Pacific, in 2014 and 2015 were particularly strong.
Another likely cause of increased water temperatures locally, according to Boustany, is the “warm blob” phenomenon. Warm water temperatures are usually in the tropical regions, but this was unusually warm water way up north near Washington state.
“It propagated down to Northern California and was here before the last big El Niño. That is something that we are not used to seeing. This warm blob was really something new,” he said.
According to the U.S. National Park Service, the blob is thought to have been caused by warmer air temperatures, changes in wind speed, duration and direction and a persistent mass of warmer water near the equator.
He added that global impacts in temperatures could also cause changes to the California coastal waters.
The resulting effect is a chain reaction that starts with little things like zooplankton and goes all the way to the top of the food chain.
“All of these things are related,” Boustany said.
According to the Environmental Protection Agency, “The ocean has become more acidic over the past few decades because of increased levels of atmospheric carbon dioxide, which dissolves in the water. Higher acidity affects the balance of minerals in the water, which can make it more difficult for certain marine animals to build their protective skeletons or shells.”
According to the OEHHA, “ocean acidification adds to the already naturally high levels of CO2 in the waters off California. Here, a wind-driven process called “upwelling” brings deeper, CO2-rich waters to the surface. As a result, California’s coastal waters may reach acidic conditions before other areas of the world, allowing for the early examination of the impacts of ocean acidification.
These impacts include shell dissolution and inhibited shell or skeletal formation in some species; impaired physiology and behavior in fish which are sensitive to even small changes in water chemistry and could result in altered pH in fish blood and impair hearing or the ability of fish to navigate effectively; disrupted marine ecology; increased impacts of other stressors on coastal ecosystems; and potential losses to the seafood industry as it could impact many economically important species and California’s commercial and recreational seafood industries are critical to its coastal economies.
“When you have effects of upwelling and more (carbon dioxide), that can cause a low pH,” Boustany explained, “it can affect zooplankton and even commercially important animals like oysters. Low pH dissolves their shells.”
In California, the OEHHA monitors pH levels from a sensor array near Santa Barbara. They measure carbon levels and pH both near the shore and 140 miles out to sea. While both areas show increases, the change is more dramatic closer to shore. However, data for California has only been collected since 2010, and is not considered a large enough data set to create conclusions from.
A similar monitoring station set up in the Hawaiian islands has been operational since 1988 and represents the longest-running measurement of ocean acidity in the Pacific. The data collected there shows the CO2 levels have increased steadily at the rate of 1.92 microatmospheres per year (µatm/year), and the pH has decreased at the rate of 0.002 µatm/year per year from 1988 to 2015.
With warmer water and a lower pH, there can also be a change in oxygen levels in the water.
“There has been an increase in the frequency of marine dead zones, low oxygen areas. It’s associated with things like red tide and algae blooms,” Boustany said.
According to the Smithsonian, a particularly bad algal bloom will not only smell nasty enough to repel beachgoers, it can also cause illness to swimmers. Beach closures become necessary and can cause significant losses for the tourism industry. The National Oceanic and Atmospheric Administration estimates toxic algal blooms account for the annual loss of roughly $82 million in sales for restaurants, hotels and other tourism industries within the United States.
Shellfish, and all the things that eat them, naturally accumulate the toxins as they filter algae from the water for food. Consumption of tainted shellfish can lead to a serious illness that includes digestion issues, tingling sensations, a rapid heartbeat, coordination problems or even death when medical treatment is not quickly sought after.
The recent Domoic acid event that sickened and killed hundreds of local marine mammals (and a few people) and delayed and damaged the local Dungeness crab season is an example of the type of algal bloom event that can have devastating impacts across the board.
Rising sea levels
According to the OEHHA, heat-driven expansion of ocean water accounts for about half of the global sea level rise in the past century. The other major contributor to sea level rise is water from melting ice caps, polar ice sheets and mountain glaciers. Sea levels have generally risen along the California coast, consistent with global observations.
Since, according to the OEHHA, more than 70% of California’s residents live and work in coastal counties, where almost 86% of the state’s total gross domestic product is generated, managing these impacts is crucial for humans and wildlife alike.
The OEHHA uses three tide gages — in Crescent City, La Jolla and San Francisco — to measure sea rise.
According to their research, sea level has risen by about seven inches since the year 1900 in San Francisco and by about six inches since 1924 at La Jolla. Sea levels generally peak during years when El Niño conditions are present, and levels at all three locations on the graph rose in relation to both El Niño conditions and the warm blob.
Sea level rise can have significant impacts on human populations, but it can also affect things like availability of breeding and pupping grounds for seal and sea lion species and damage fragile estuaries and river flows that fish, birds and invertebrates count on for breeding, feeding and raising young.