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Eutrophication

Photo: Hans Hillewaert

Eutrophication is an excessive growth of plant and algae in marine environments. This is usually caused by excessive amounts of phosphorus, nitrogen, and other nutrients that allow the growth of these organisms. This overload is a result of runoff from agricultural land. As a result of these excess nutrients, increases in macro algae deplete the aquatic ecosystem of oxygen and it leads to the mortality of benthic animals and fish.

Invasive Species

Photo: CDFW (2017)

Photo: Wikimedia Commons

Ballast Water

Another threat to coastal ecosystems is the introduction of invasive species. Invasive marine organisms are often introduced through ballast water. Ballast water is loaded onto cargo ships in order to adjust the buoyancy of the ship, depending on the cargo load. The loading from one source port can bring non-native species into a new ecosystem when the ballast water is discharged at a second destination port. Through ballast water, about 7000 species are estimated to be moved around the world on a daily basis (Carlton 1999).

Photo: Wikimedia Commons

Chinese Mitten Crab

The Chinese Mitten Crab is native to the Pacific Coast of China and Korea. They were first found in the San Francisco Bay in 1992 and their distribution can now be found from northern Colusa County to Southern Merced County. This invasive crab can cause damage to flood control systems, compete for food with local crayfish, and prey on fish eggs.

Photo: Matthieu Sontag

Clubbed Tunicate

The Clubbed tunicate is native to Eastern Asia. These filter feeders were first found on the Pacific Coast in the 1930’s. This organism has the ability to withstand dramatic fluctuations in salinity and temperature. Due to their resilience, they outcompete native organisms for food and decline native populations.

Photo: National Park Service

Asian Kelp

The Asian Kelp is native to Japan. It was first found in Southern California but has made its way up to San Francisco. This kelp can outcompete native species for resources and ultimately alternate established ecosystems.

Shoreline Erosion

Shoreline erosion is mainly caused by urban development. Natural vegetation slows coastal water flows, but the introduction of roads, parking lots, and sidewalks allows water flow to travel faster and in greater quantities. Water overflows stream banks and this leads to shoreline erosion which threatens coastal habitats. Loss of the shoreline leaves coastal areas vulnerable to future damage.

Photo: DBW

Global Warming & El Nino

Photo: NASA

Climate change, as a result of Global Warming, has intensified the impact of El Niño events. El Niño is characterized by complex weather patterns due to fluctuations in temperature between the ocean and atmosphere in the Pacific. Across California, El Niño often causes increased rainfall, floods, landslides, and coastal erosion. The increased ocean temperatures prevent upwelling of cold nutrient-rich water which sustains phytoplankton. This in turn affects the food supply of other coastal animals such as birds and fish.

Sourceshttp://marinespecies.org/introduced/wiki/Eutrophication_in_coastal_environments#cite_note-7https://wildlife.ca.gov/OSPR/Science/Marine-Invasive-Species-Program/Definitionhttps://www.nps.gov/articles/invasive-kelp-spreads-into-new-territory.htmhttps://sciencing.com/about-6085011-erosion-effects-ecosystem.htmlhttps://oceanservice.noaa.gov/facts/ninonina.htmlhttps://ucmp.berkeley.edu/education/dynamic/session4/sess4_hydroatmo3.htm#:~:text=Impact%20on%20California&text=Instead%20of%20coming%20ashore%20in,%2C%20landslides%2C%20and%20coastal%20erosion.