Lab 11 – SHELL SHOCKED: THE EFFECTS OF ACIDIFICATION ON MARINE LIFE
Oyster larvae and acidification by Oregon State University is published as CC BY-SA 2.0 on flickr.
The image above shows one-day old oyster larvae raised in a shellfish hatchery in Washington. Though these two larvae share the same parents, they look quite different. Why? The smaller, more “ragged” oyster larvae on the right was raised in lower pH, or more acidic waters. Recent declines in ocean pH have the same ultimate drivers as climate change: a rapid increase in atmospheric CO₂ and these changes can have wide-ranging impacts on marine life. This lab chapter will walk you through the connection between CO₂ and pH and help you to understand the biological and physical processes that influence ocean chemistry.
Watch this video and answer the quick check questions that follow.
Quick Check Questions
Orientation Question
- According to the video, why should people care about ocean acidification?
Learning Outcomes
- LO1. Identify long-term trends in atmospheric CO₂ and their relationship to ocean CO₂ through ocean-atmosphere gas exchange
- LO2. Link patterns in ocean CO₂ to ocean pH
- LO3. Identify the relationships between biological processes and ocean chemistry
- LO4. Describe how coastal upwelling impacts surface CO₂ and pH
- LO5. Analyze real oceanographic data visualized in a variety of formats, including time series data, correlation data, vertical profile data, and spatial data
Background Information
pH is a measure of the acidity or basicity of a solution, specifically, it’s the negative logarithm (base 10) of the hydrogen ion concentration ([H+]). Lower pH values indicate higher concentrations of hydrogen ions (H+). The “log” in pH means that each whole number on the pH scale represents a tenfold difference in hydrogen ion concentration. At pH = 7 (pure water), hydrogen ion and hydroxide ion activity are equal. Solutions with pH values above 7 have lower concentrations of H+ ions and are considered basic or alkaline. Solutions with pH values below 7 have higher concentrations of H+ ions and are considered acidic. The term acidification refers to a decrease in pH.
A primer on pH by NOAA is licensed under the public domain. Original Source.
Quick Check Questions
The pH of the ocean is slightly basic, with an average pH of about 8.1. Even a small decrease in ocean pH, a phenomenon known as ocean acidification, can have significant impacts on marine life and ecosystems. Lowering the pH reduces the availability of calcium carbonate, a key building block for shells and skeletons, potentially leading to shell dissolution and other physiological problems in certain species.
When these species struggle to survive, it disrupts the entire marine food web, affecting fish and other species that depend on them for food. Millions of people depend on fish and shellfish for protein and income. Acidification threatens some species at the base of the food chain (e.g., plankton) and economically important species like oysters, clams, and crabs, jeopardizing food security and livelihoods.
In this lab you will learn about how changes in carbon dioxide (CO₂) concentrations affect the pH and how the ocean responds to these changes in pH.
Review concepts:
Key terms: dissolved oxygen, hypoxia, anoxia, Submerged aquatic vegetation, Algae/Seaweed, phytoplankton, CO₂, acidification, pH, calcium carbonate, photosynthesis, upwelling, carbonate, temporal patterns, fossil fuels, flux, climate drivers
Data collection:
