Scientists successful at recovering underwater forestry

The restored forests were at levels similar or even superior to untouched ones.
Loukia Papadopoulos
Underwater forestry.jpg
Underwater forestry.


After 10 years of restoration efforts, scientists have successfully helped a damaged underwater forest regrow to a degree comparable to forests that have never been disturbed. The development offers hope for other regions in the world sabotaged by climate change and human impact.

This is according to a report by published on Friday.

"Macroalgal forests are found along over one-third of the world's coastlines and underpin entire ecosystems," said Dr. Emma Cebrian of the Centre d'Estudis Avançats de Blanes, corresponding author of the new study.

"In 2011, a restoration action took place in the Bay of Maó, Menorca, where a macroalga species was reintroduced in the area where it used to thrive. After 10 years, we found that the associated algal species returned to the habitat, and with them, the ecosystem functions they provide."

Cebrian and her team investigated five localities of Gongolaria barbata, a species crucial to maintaining seaweed forests, to understand how restoration of these species can work to revive and replenish the ecosystem.

"Among all seaweeds, canopy-forming macroalgae provide structure to the ecosystem similar to trees in a terrestrial forest," said Cristina Galobart, first author of the study, also based at the Centre d'Estudis Avançats de Blanes. 

"They influence the local environment by altering, for example, the light and water flow. These modifications in the environment create ecological niches that other species can profit from."

The scientists sought to measure the function of the restored forest by capturing quantifiable traits in the target species that represent the health of the ecosystem. They analyzed a series of 14 traits, such as the size of specimens and whether they were from a longer-living or slower-growing species. 

The team focused on a variety of localities, both restored and new, collecting samples from each of these locations for identification and analysis. They then dried and weighed the samples to measure the abundance of each species present.

A wider variety of species

The results indicated that the restored locality was made up of a wider variety of species than the untouched locality and that the species that make up restored ecosystems may be different to the originals while still filling the same niche in supporting local biodiversity. 

The restored locality also showed signs of long-term recovery such as greater structural complexity and species with longer lifespans. This diversity was estimated to offer potential benefits for the future since a more diverse seaweed forest may be better equipped to respond to environmental issues.

"We demonstrated that a single restoration action, plus the removal of the cause of degradation, can lead to the recovery of not only a single species but also the associated ecosystem functions," told Cebrian. 

"Adding information from other restoration initiatives will help to completely understand how functionality is recovered in different habitats, species, or environmental conditions."

The study is published in Frontiers in Marine Science.

Study abstract:

Active restoration actions are becoming increasingly common for the recovery of degraded ecosystems. However, establishing when an ecosystem is fully restored is rarely achieved, since the recovery of entire communities needs long-term trajectories. The lack of evidence of success is even more severe in marine ecosystems, especially in the context of macroalgal forests, where beyond the vegetation structure and species diversity there is no approximation determining the recovery of the overall functionality. Trait-based ecology facilitates the link between species composition and ecosystem functions and processes. In this study, we used a trait-based approach to assess functional recovery ten years after the start of a restoration action in a marine macroalgal forest. Species and functional diversity were compared among the restored locality, a nearby locality where the expansion of the restoration is naturally occurring, a neighbouring non-restored locality (at a distance of a few meters), and the only two remaining localities dominated by the same structural macroalga that were used as reference (non-perturbed). Species diversity and composition of the restored locality were similar to those found in reference macroalgal forests, while the non-restored and expansion locality showed different species composition and lower species diversity. Functional richness was 4-fold higher in the restored locality than in the non-restored one, even surpassing one reference macroalgal locality. The restored locality showed a greater number of trait categories, especially traits related to higher structural complexity and longer life spans, indicating changes in ecosystem functions and processes. The restoration of a canopy-forming macroalga is the first step to achieving the recovery of an entire macroalgal forest (i.e., associated species and functional diversity). The application of traditional taxonomical indices plus functional parameters provides useful insights into the assessment of the success of restoration actions at the community level, emerging as a promising approach to be replicated and contrasted in other marine and terrestrial ecosystems.