Aurora M Ricart: “Losing marine forests would lead to a great loss of biodiversity, a decrease in water quality and coastal protection”

Aurora M Ricart is a marine ecologist studying global change in coastal marine ecosystems. She graduated in Biology at the University of Valencia (Spain) and holds a Master and Ph.D. in Ecology from the University of Barcelona (Spain). She started her postdoctoral research in the United States, first at the Bodega Marine Laboratory of the University of California, Davis, and then at the Bigelow Laboratory for Ocean Sciences. Now she has returned to Spain, and concretely to the Institut de Ciències del Mar (ICM-CSIC), thanks to a Marie Sklodowska-Curie grant that brought to life the SeapHorest Project,  which will allow her to investigate how natural ecosystems are impacted by climate change and other anthropogenic activities. Also, Aurora will delve into how natural ecosystems can help mitigate and adapt to climate change as well as serve as multi-stressor refugia.

1. What kind of forests lie underwater?

Marine forest is a common name used to designate underwater vegetated ecosystems. These ecosystems are composed of marine macrophytes habitat forming species such as seagrass meadows or macroalgal beds. Similar to terrestrial forests, marine forests create complex habitats that provide food resources, shelter and nursery grounds for many marine organisms and can help mitigate and adapt to climate change effects by sequestering carbon. Seagrass meadows (~70 species total) are flowering plants present in coastal areas from tropical to subpolar regions. Macroalgal beds including green, red and brown algae (~10000 species total), are globally distributed, although the term marine forest is commonly used to refer to large brown algae (kelps and fucoids).

2. Which threats are these ecosystems currently facing?

In general, by climate change effects, although what affects them most is increased seawater temperatures and some anthropogenic activities that involve high nutrient inputs which can degrade water quality and generate eutrophication. However, they are also negatively affected by coastal constructions, which entail direct habitat loss and changes in sedimentation patterns and light availability. On the other hand, natural disturbances such as storms, wave action, and extreme weather events, can also cause physical damage to marine forests. For this reason, it is important to implement measures such as sustainable fishing practices, reducing pollution, and protecting coastal areas if we really want to preserve these ecologically valuable ecosystems.

3. What if we were to run out of forests underwater?

It would have significant ecological, environmental, and socio-economic consequences.  For example, a great loss of biodiversity and fisheries decline could occur, since these ecosystems are biodiversity hotspots supporting a wide range of marine species including commercially important species. In addition, the disappearance of these forests would lead to a lack of coastal protection, since the different species that form them help stabilize marine sediments and act as natural buffers against storms, wave action and erosion. On the other hand, it would decrease water quality and the ocean's capacity to capture carbon dioxide (CO2), which could lead to an increase in CO2 levels in the atmosphere.

4. Could these forests reverse the problem of ocean acidification?

Not entirely, although they could help mitigate their effects on a local scale. Raising anthropogenic carbon dioxide (CO2) emissions and consequent changes in seawater acidity can differentially and interactively affect marine biota with deleterious consequences for many ecologically and economically important species. In this scenario, marine forests have been suggested as potential nature-based solutions to locally mitigate ocean acidification effects. This is an emerging line of research, although some papers have already been published based on experiments both in the field and in the laboratory with promising results.

5. If underwater forests disappear, which other ocean carbon sequestration mechanisms exist?

There are many carbon dioxide strategies (CDR) currently being proposed both in land and in the ocean that aim to reduce the concentration of carbon dioxide (CO2) in the atmosphere. These involve specific approaches and technologies and most of them are still in developmental stage. Just to mention some in the ocean, there is a lot of research happening now regarding ocean alkalinity enhancement, afforestation and seaweed sinking, enhanced weathering, conservation of blue carbon habitats, ocean fertilization, or direct air capture and sequestration in the ocean floor. However, implementing them requires careful consideration of potential environmental impacts and ethical considerations. Additionally, these strategies should not be viewed as a standalone solution to climate change. They should be part of a comprehensive approach that includes reducing greenhouse gas emissions, promoting sustainable practices, and transitioning to a low-carbon economy.

6. How do you study the impact of global change on marine forests?

I use a combination of field and lab experiments at the landscape and ecosystem scale to understand marine forests functioning, dynamics, and responses to environmental changes. Towards that purpose, I draw on techniques that span ecology, ecophysiology, biogeochemistry, and oceanography. Most of the field work that I do is underwater and requires scientific diving. While in the laboratory, I run experiments in aquaria or mesocosmos in order to control all environmental parameters and test future scenarios of global change.

7. Who can benefit from the results of your research?

So far, the results of my research have benefited environmental managers and policy makers that aimed to improve conservation, protection and restoration of coastal areas; develop national or regional Greenhouse Gas Inventories; increase carbon sequestration through the application of CDR strategies; or adapt aquaculture activities to increase sustainability and optimize sequestration of CO2 in seawater (specially when cultivating calcifying organisms and seaweed).

8. Which future awaits marine forests?

Unfortunately, these ecosystems have declined greatly over the last century, although recent studies show that protection and conservation measures can reverse the current situation. This is important, among other things, because marine forests are among the few species that can benefit from rising CO2 concentrations. However, the multiple impacts they are currently facing prevent us from knowing what the future holds for them. What is clear is that the human species has the capacity and technology to reduce these impacts. The question is when we will make this a priority.