Increasing Frequency of Ocean Storms Could Alter Forest Kelp Ecosystems – ScienceDaily

Researchers from the University of Virginia and the University of California at Santa Barbara experimentally simulated the loss of underwater giant kelp forests at four locations off the coast.

from Santa Barbara and found that the increased frequency of storms – as predicted by some climate change models – could dramatically alter the ratios and types of marine life that live along the California coast.

"We found that the frequency of disturbances was the most important factor affecting the biodiversity of kelp forests, while the severity of disturbances in a given year played a minor role," said the researcher. Principal Max Castorani, professor of environmental science at the AVU.

The study appears online on October 30 in the newspaper Ecologyand comes as scientists try to anticipate the ecological consequences of a changing climate. This is one of the few long-term experiments to examine how kelp forests, which are the main coastal marine habitats in the world, could change over time if climate model predictions materialize in nature as many scientists predict. Some climate forecasts indicate that the frequency and severity of storms will increase, as is already happening in some areas.

To arrive at their conclusions, the researchers counted and measured more than 200 species of plants, invertebrates and fish in large experimental kelp forests off Santa Barbara every three months over a nine-year period. They found that annual disturbances in which kelp forests were experimentally reduced and reduced from year to year, as occurred during severe winter storms involving large waves, resulted in the doubling of smaller plants and invertebrates. set at the bottom of the sea (algae, corals, anemones, etc.). sponges), but also resulted in a 30-61% reduction in the number of fish and shellfish, such as clams, sea urchins, starfish, lobsters and crabs.

"Our results surprised us because we expected that a single severe winter storm would result in big changes in the biodiversity of kelp forests," Castorani said. "Instead, the number of disturbances over time had the greatest impact, as frequent disturbances prevent the recovery of giant kelp, with significant consequences for the surrounding marine life."

Giant kelp, which is the largest of all algae, can reach a hundred meters from the sea floor to the surface of the water, creating a dense plant cover, similar to a terrestrial forest, which provides from the shade and shelter to organisms further away in the water column and on the bottom of the sea. When the forest is destroyed by a big storm, the "understorey" becomes brighter with the sunlight, but it is physically less complex and more productive, which affects the balance of species diversity. While it is normal for this to happen periodically when large storms at sea cause destructive waves to the shoreline, forests usually recover quickly. But a greater frequency of storms would repeatedly hinder the recovery, which would result in a significant alteration of marine life.

Predictions of climate change predict an increase in the frequency and severity of storms over the next decades, which could lead to profound changes in the biodiversity of kelp forests, as suggested by the new study. The repeated loss of giant kelp creates ecological "winners and losers", said Castorani, "intelligent" creatures – algae, sponges, anemones and gorgonians – are more likely to thrive, while many fish commercially and recreationally challenged crabs, lobsters, whelks and clams are declining.

The experiment was conducted on the long-term ecological research site on the Santa Barbara coastline of the National Science Foundation. The NSF funds many long-term research projects around the world, designed to get an overview of changes in ecosystems over decades and beyond.

"It is significant to note that the severity and frequency of the disturbances affect kelp bed communities in a variety of ways," said David Garrison, director of the NSF's Long-Term Ecological Research Program, who funded the project. 39; study. "We need this kind of research to predict what the future kelp bed communities will look like and what ecosystem services they will provide."

Castorani said the nine-year study demonstrated the value of long-term ecological research to understand environmental change as it occurs, like watching a movie about the environment rather than taking a snapshot that captures only a moment in time.

"Previous research was largely focused on the response to an isolated event, but our new experience shows that it is important to study the repeated disturbances over several years," he said. "We could not have understood the ecology of this system without the long-term support of NSF's LTER program."

In addition to his research in California, Castorani also conducts biodiversity studies at the UVA Anheuser-Busch Coastal Research Center, located on the east coast of Virginia, where NSF has been funding an ecological research project since 1987. long-term nature reserve Nature Conservancy Nature Reserve since 1987..