An ocean heavily populated by invasive species of algae, jellyfish, crabs and shellfish may be the future if ocean acidification continues.
“A rapidly growing body of research indicates that ocean acidification will severely disrupt marine ecosystems, since it alters the balance of success between competing organisms. Ocean acidification can impact a wide range of processes across marine taxa, including photosynthesis, acid-base homeostasis, calcification and behavior,” Plymouth Univ. researchers write in Research and Reports in Biodiversity Studies.
However, “the traits that help many invasive organisms succeed, such as wider physiological tolerance and reproductive advantage in the face of multiple stressors, are traits that look set to help them in an acidifying ocean.”
The study was prompted when Prof. Jason Hall-Spencer, the study’s lead author, witnessed the marine life thriving near volcanic sites in the Mediterranean. Invasive species, such as killer algae (Caulerpa taxifolia), thrived and benefited from higher carbon dioxide in the water. Killer algae is so toxic herbivores stay away from it.
“We are witnessing the spread of marine life that cause problems—such as toxic jellyfish blooms and rotting algal mats,” said Hall-Spencer. “Based on a synthesis of evidence available to date, we predict the problems associated with harmful marine life will get worse in response to rising (carbon dioxide).”
Elevated carbon dioxide levels are expected to help extend the range of alga Neosiphonia harveyi. Previous experiments show increased availability of dissolved inorganic carbon lets the species cope in colder temperatures, potentially allowing it to spread to higher latitude regions.
In culture conditions, the jellyfish Aurelia labiata is highly resilient to acidification, though the development of its statolith slows. The researchers believe jellyfish blooms are resilient to the levels of ocean acidification expected this century.
“The role of adaptation has not been explored extensively with regard to ecologically harmful marine species, however, the increasing rate of ocean acidification is narrowing the time window available for marine organisms to adapt, thus organisms with resilient genotypes present in current populations have an advantage,” the researchers write.
However, some invasive species have problems with ocean acidification, especially in larval stages. The American slipper limpet (Crepidula fornicate), which has spread to Europe and is one of the 100 most invasive species, faces a greater risk of predation due to ocean acidification negatively affecting its shell growth. The red king crab (Paralithodes camtschaticus) and the mollusk Urosalpinx cinerea show similar difficulty in larval stages.
“There will be winners as well as losers as (carbon dioxide) levels ramp up, just as there were in previous mass extinctions,” said co-author Ro Allen. “The spread of harmful marine organisms should be factored into risks of rising (carbon dioxide) emissions.”