Effects of Ocean Acidification on Marine Fauna and Ecosystem Processes in the Northwest Atlantic

Description

As seawater absorbs atmospheric CO₂, increased ocean acidification resulting from elevated pCO₂ concentrations can disturb the physiology and nervous systems of marine organisms. However, sensitivity to the effects of ocean acidification can vary from species to species and among individuals within a species, which indicates that adaptation to acidification is possible. This project aims to explore the impact that acidification has on key ecosystem processes, test the effects of increased acidity on key species, and determine the geographical range of species that are considered to be acid-sensitive.

Results: Researchers studied the effects of ocean acidification on several species, including American lobster, Northwest Atlantic cod, and northern shrimp, as well as various species of phytoplankton and copepods. Results showed that hatching success was lower for Northwest Atlantic cod that were exposed to more acidic pH levels from fertilization until hatching. However, when comparing the ability to tolerate more acid conditions in the offspring of different males, there was evidence that Northwest Atlantic cod has some genetic capacity to adapt to pH changes. Preliminary observations from the study of northern shrimp respiration at various pH levels showed a greater mortality rate when the pH was more acidic.

Researchers also studied the effects of acidity on various ecosystem processes in the St. Lawrence Estuary. Results suggest that some microbes are more sensitive to ocean acidification, which may have consequences to biodiversity and functioning of the food chain. However, phytoplankton appears to be relatively resistant to acidification.

Additional experiments are planned for the long-term exposure of cod to various pH levels and for studying the tolerance of lobster larvae and copepods to acidic conditions. Researchers are also in the process of generating a list that indicates the relative sensitivities of each species to ocean acidification.

Canada's Coastal Waters and Ocean Acidification

Canada's cold coastal waters may be particularly prone to acidification due to the natural occurrence of under-saturated waters at shallow depths (Pacific coast), or large freshwater input (Arctic coast).

Freshwater input from runoff and ice melt reduces the ocean's capacity to buffer against changes in pH. Runoff may also contain organic matter from land which can also increase acidification.

Program Name

Aquatic Climate Change Adaptation Services Program (ACCASP)

Ecoregion(s)

Atlantic: Newfoundland, Labrador Shelves

Principal Investigator(s)

Edward Trippel
Fisheries and Oceans Canada

Michel Starr
Fisheries and Oceans Canada

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