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Coastal Hazards

Marine Biophysical Conditions and Processes Research

Photo credit: Randy Baumhover, Shore Acres State Park, Oregon (2014)

The term “biophysical” describes the abiotic and biotic conditions of an environment and includes chemical, biological, physical and ecological components. These conditions and processes can occur naturally (e.g, currents), and/or be influenced by anthropogenic drivers (e.g., ocean warming). Research may focus on the processes themselves or their effects on and interactions with marine organisms. Research on this topic includes ocean warming, ocean acidification, bathymetry, currents/upwelling, sediments, waves, tides, hypoxia, and harmful algal blooms (HABs).

Oregon Research Highlights

  • Ocean warming refers to increases in temperature associated with greenhouse gas emissions. Monitoring of ocean temperature has shown that sea surface temperatures are rising globally and heat energy storage is increasing in the top half-mile of water. Warmer temperatures can lead to changes in coral reef and rocky intertidal ecosystems, fisheries, and storms. 
  • Ocean acidification is a decrease in the pH of surface ocean waters due to increases in atmospheric carbon dioxide (CO2), 30% of which is absorbed by the ocean. Similar to ocean warming, this increase is a result of burning fossil fuels, as well as land use change (e.g., deforestation). As the ocean becomes more acidic, chemical reactions occur that lead to a lower abundance of carbonate ions, which are essential for calcifying organisms that use them for building shells or other structures (e.g., corals, sea urchins, oysters, plankton, etc.).
  • Bathymetry describes the terrain of the ocean bottom, such as the depth, shapes, and features of the sea floor. Variation in these physical conditions determine which biological communities can be supported by the surrounding environment.  
  • Currents are continuous and directed movements of water that are driven by winds, water density, tides, and influenced by coastal and seafloor features. Currents affect marine organisms in several ways by transporting nutrients, larvae and small organisms. These processes are extremely important for species with limited mobility, particularly for feeding and reproduction. 
  • Upwelling is a type of current that occurs when winds blow across the ocean surface and push water away. This water is then replaced by cold, nutrient rich water that supports phytoplankton and seaweed, which in turn provide energy for consumers such as fish and marine mammals.  
  • Waves are primarily caused by friction between wind and the water surface. Wave size is influenced by wind speed, duration, and distance. Breaking waves are those that become too unstable due to friction between the seafloor and the water.
  • Tides are long-period waves caused by the gravitational pull of the sun and moon on the earth. On the coastline, tides appear as a rise and fall of the sea surface that occurs daily. High and low tides occur when the sea level reaches the highest and lowest point at a particular location. 
  • Hypoxia refers to low or depleted oxygen in an area of the ocean which can lead to a “dead zone” or place that cannot sustain life. This commonly occurs when some species of algae are overgrown, and then deplete oxygen as they die and decompose. When large stretches of water become hypoxic, die-offs of fish, shellfish, corals and plants may occur. 
  • Harmful algal blooms (HABs) occur when colonies of algae overgrow and produce toxins or cause other harm to humans and marine organisms (e.g., hypoxic dead zones). Climate change and increases in nutrient pollution are leading to more frequent occurrences of HABs and in additional locations.  

Oregon Research Highlights

Barton et al. (2012) found that ocean acidification associated with periodic seasonal coastal upwelling affects Pacific oyster (Crassostrea gigas) larval development and growth. They investigated this phenomenon after local conditions were having an impact on oyster hatchery production. Starting in 2006, the Whiskey Creek Shellfish Hatchery in Netarts, OR experienced issues with larval production, which was originally thought to be associated with presence of pathogenic bacteria. However, issues continued to occur long after water quality monitoring revealed absence of bacteria. Through monitoring of pH levels in the bay and analysis of hatchery records, the researchers found that decreases in aragonite saturation (measure of carbonate ions in water) due to upwelling were the likely cause of decreases in oyster larval production and growth. 


Barton, A., Hales, B., Waldbusser, G. G., Langdon, C., & Feely, R. A. (2012). The Pacific oyster, Crassostrea gigas, shows negative correlation to naturally elevated carbon dioxide levels: Implications for near-term ocean acidification effects. Limnology and Oceanography, 57(3), 698–710.
Authored by Amy Ehrhart, Portland State University (2017)