World Oceans Day

This Sunday, June 8th, is World Ocean Day! The Rogue River flows from the high elevations near Crater Lake to the Pacific Ocean at Gold Beach. It is the seventh longest river in the state of Oregon, but we’re here to talk about the largest ocean in the world. The Pacific Ocean covers about 155 million square kilometers, and is by far the largest ocean (the Atlantic Ocean is the second largest at 106 million square kilometers).

Oceans are an important habitat for many fish & wildlife, and many of our native fish in the Rogue spend years in the ocean before returning to spawn. Salmon, Steelhead, Lamprey, and Sturgeon are all anadromous fish (in the Rogue)– meaning that during their life cycle they utilize both fresh and saltwater. Anadromous fish spawn in cold freshwater tributaries and migrate to the ocean to grow into adulthood. Productive salmon populations support commercial & sport fisheries, subsistence fishing, and salmon-based cultures.

Why go to the ocean?

It comes down to food availability– quantity and quality! There are a lot more things to eat and space to grow in the ocean compared to the rivers and streams where they begin their lives. It’s like going to the gas station compared to a grocery store to find food every day: which would you choose? When these fish return to their spawning grounds as full grown adults, they are much less vulnerable to predation and can produce a large amount of eggs.

Salmon are a key piece of the marine food-web, which you can think of in a sort of pyramid. The energy available in the lower trophic (pyramid) levels– like krill and phytoplankton– are key to the higher trophic levels’ survival. Salmon are often referred to as a “keystone” species, meaning their presence and abundance influences the health of that ecosystem as a whole. There is a long-standing connection between people and salmon, and the importance of salmon as keystone species makes them a target for restoration and ecosystem health.

example of energy flow through a marine ecosystem

Salmon & Steelhead have similar life cycles and belong to the Salmonidae Family, so they are often grouped together in terms of management. There are six species in the Salmonidae Family that spend part of their life cycles in the Pacific Ocean: Chinook Salmon, Chum Salmon, Coho Salmon, Sockeye Salmon, Pink Salmon, and Steelhead Trout. Of those, Chinook, Coho, and Steelhead are native to the Rogue. In our region, Coho Salmon are a protected species listed as threatened under the Endangered Species Act. Our oceans provide essential habitat as these species grow and prepare for their migration upstream, so protecting them is vital to the survival of these charismatic and culturally significant species.

Photo Credit Eiko Jones: (left to right) Coho, Steelhead, Chinook

Oceans & Climate

Ocean currents act as conveyor belts of warm and cold water, sending heat toward the polar regions and helping cool tropical areas. El Niño and La Niña make up two of the three states of the constantly changing El Niño/Southern Oscillation (ENSO) that can affect weather patterns around the globe. The cycling of ENSO between El Niño and La Niña is irregular, but recurs about every two to ten years. Ocean currents regulate global temperatures by transporting warm water from the equator to the poles and cold water from the poles to the equator, distributing solar energy and influencing climate. El Niño/Southern Oscillation (ENSO), a recurring Pacific Ocean pattern with El Niño (warm) and La Niña (cool) phases, disrupts global weather by altering rainfall and temperatures. These irregular two-to-ten-year cycles affect various sectors, making ENSO prediction vital for mitigating extreme weather impacts. (Learn more about oceanic oscillations here.)

“Conveyer Belt” Graphic Credit: NASA

Salmon populations are continually affected by shifting weather patterns that affect their habitat quality and quantity (see here). El Niño weather patterns typically mean a warmer and drier PNW winter, which is not ideal for coldwater salmon in our region (although it brings milder and wetter winters to coastal Alaska, which benefits their salmon populations). La Niña winters, conversely, offer a boost in stream flows from rain and snowmelt, leading to more suited cold habitat in the PNW (but not Alaska). These observations were first found by fishermen, and they continue to be studied today. It’s an example of how the natural world pushes and pulls, but the impacts humans have on these environments can cause extra strain, even in the best of years.

The Give & Take

Oceans are vital not only as diverse habitats teeming with life but also as the planet's largest carbon sink, playing a crucial role in regulating the Earth's climate. They have absorbed over a quarter of the carbon dioxide (CO2) emissions released by human activities, effectively mitigating the impacts of global warming by removing a significant portion of greenhouse gases from the atmosphere. Certain coastal ecosystems, including mangrove forests, seagrass meadows, and salt marshes, stand out as particularly efficient carbon storage powerhouses, sequestering vast amounts of carbon in their biomass and underlying sediments.

However, this crucial absorption of CO2 comes at a significant cost, leading to a phenomenon known as ocean acidification. As CO2 dissolves in seawater, it reacts chemically to form carbonic acid, which in turn lowers the ocean's pH. This increase in acidity has profound and detrimental effects on marine life and the delicate balance of ocean ecosystems. Many marine organisms, such as oysters, clams, shrimp, and coral reefs, rely on calcium carbonate to build and maintain their shells and skeletons. Ocean acidification reduces the availability of carbonate ions, making it more difficult for these organisms to calcify and even causing existing shells and skeletons to dissolve.

The impacts of ocean acidification cascade throughout the entire marine food web. The weakening or loss of calcifying organisms at the base of the food chain can have devastating consequences for the species that depend on them for food and shelter, ultimately affecting larger predators and even human seafood supplies. Coral reefs, which provide critical habitat for a vast array of marine species, are particularly vulnerable to ocean acidification, leading to coral bleaching and reef degradation. 

Scientific evidence suggests that the ocean's capacity to absorb CO2 is not limitless and that the efficiency of this crucial carbon sink may be slowing down. This implies that the oceans will become less effective at buffering the impacts of our ongoing emissions in the future, potentially accelerating the rate of global warming and intensifying the consequences of ocean acidification. Understanding and addressing the complex interplay between the ocean's role as a habitat and its capacity as a carbon sink is crucial for safeguarding marine ecosystems and mitigating the long-term effects of climate change. Urgent action to reduce CO2 emissions is essential to protect the health and resilience of our oceans.

Image Credit: NOAA

We need healthy oceans to breathe, to nourish ourselves, and ultimately– to survive. Even if you live in the most landlocked area (Nebraska...?) you are still at the mercy of the ocean. Let’s work to protect it and help it recover from the many human-caused maladies floating in the great blue.