Underwater macroalgal forests are among the most important ecosystems in our oceans. Their fronds and branches create a rich canopy, which harbours a diversity of species that are critical to nearshore trophic networks. Additionally, macroalgal forests offer a wide range of goods and services to populations living on the coast. They help ensure high water quality, provide refuge to species of commercial interest and are an important tourist attraction for divers, to list just a few of their critical functions.
Macroalgal forests face a growing threat and we may be losing them at a rapid rate. One of the reasons for this loss is overgrazing effect by sea urchin herbivores. Normally, sea urchins would be naturally controlled by predatory fish, but with rampant overfishing, populations of sea urchins can grow to outbreak proportions allowing them to completely overgraze underwater forests. In addition, some areas (such as the Eastern Mediterranean) have suffered major losses of macroalgal forests because of herbivorous fish that enter through the Suez Canal. To add to these threats, other factors, like heat waves (that are increasing with climate change) can also cause dramatic collapses of these precious underwater forests.
As a result, areas that were once abundant macroalgal forests are being rapidly replaced by underwater deserts – barrens – dominated by overgrazed rocks rather than macroalgae. These alternate habitats are very poor, low productive ecosystems with very little biodiversity.
What are we doing?
A group of researchers from different institutions have joint efforts to study the collapse of the underwater macroalgal forests and the expansion of barrens. In particular, we are interested in understanding what characterises these new barrens in order to isolate the factors that determine their creation. We believe that monitoring already existing deserts is essential to prevent and predict the creation of new barrens along the coastline. It will help us evaluate the possibilities of recovering lost underwater forests.