Signs of latitudinal changes in the stability of rocky intertidal communities from Atlantic Canada in relation to ongoing environmental variations is the subject of a new study led by StFX biology professor Dr. Ricardo Scrosati and ex-graduate students Nicole Cameron and Julius Ellrich that has resulted in a new article recently published in the journal Frontiers in Marine Science.
"For years, since I opened the Marine Ecology Lab at StFX in 2004, the latitudinal and seasonal patterns in the abundance of intertidal algae and invertebrates along the Nova Scotia coast were relatively predictable. However, in connection with the ongoing climate and oceanographic change, these patterns are changing, some of them dramatically," Dr. Scrosati says.
"At northern locations on the open Atlantic coast of mainland Nova Scotia, the occurrence of drift ice in late winter has been consistently decreasing, likely because of the less ice formed in the Gulf of St. Lawrence in recent winters. The rarity or absence of sea ice at these northern locations now results in almost no damage to intertidal communities, which drift ice would have otherwise caused by scouring the substrate with wind and waves," he says.
Because of this, these northern intertidal communities are gaining stability, as they can develop a high biomass that persists over the years. This increased biomass is mainly a result of seaweed growth, he notes.
"However, at southern locations on the open Atlantic coast of mainland Nova Scotia, recent abiotic extremes, such as a winter cold spell and then cyclone Lee in 2023, are decimating the abundance of some intertidal species, such as mussels, while having no discernible effect on others. These abiotic changes are destabilizing these southern intertidal communities relative to what they used to be."
Overall, Dr. Scrosati says these ecological changes along the coast resemble the northward migration of community patterns and the increasing instability near the trailing edge of communities resulting from climate change, as seen elsewhere in the planet.
"We will continue to monitor this coastal system to see where things go in future years."
