- The Desertification Research Center (CIDE, CSIC- UV-GVA) presents the main ideas and questions to be solved with this new study perspective.
- Analysis of forest fire disturbances in marine systems would also help to understand the role of the oceans as carbon sinks.
A study published in the journal Trends in Ecology & Evolution by researchers from the Desertification Research Center (CIDE), a joint center of the Spanish National Research Council (CSIC), the University of Valencia (UV) and the Generalitat Valenciana, proposes, for the first time, a conceptual framework for the study of fire ecology in the marine environment. Scientists from the Biodiversity and Conservation Research Group (BIOCON) of the ECOAQUA Institute, belonging to the University of Las Palmas de Gran Canaria, collaborate in the work.
Wildfires are one of the main ecological disturbances in various terrestrial ecosystems such as boreal forests, temperate forests, Mediterranean shrublands, tropical savannas and grasslands. In these ecosystems, a significant portion of the by-products generated by wildfires (ash, smoke and sediments) reach the ocean via terrestrial runoff and rivers, and atmospheric aerosols.
With global warming, predictable trends point to a global increase in fire activity, which will result in increased deposition of wildfire-related materials in marine ecosystems. However, understanding the impact of these disturbances on these ecosystems, both on water quality and marine biota, is still anecdotal and requires further analysis.
Biological effects
"Wildfires are expected to have a significant impact on ocean ecology. Specifically, we expect forest fire by-products to increase the transport of nutrients from land to sea, alter marine chemistry and carbon and nutrient cycling, as well as phytoplankton productivity, and have both positive and negative effects on ocean biota, from microbes to mammals," explains Juli G. Pausas, CSIC researcher at CIDE who leads this work.
Prominent examples of these effects include those caused by the extensive 1997 forest fires in Indonesia, which resulted in red tides that spread throughout the Indonesian archipelago for two months. These red tides, accompanied by oxygen depletion, caused significant mortality of phytoplankton, zooplankton, and benthic (bottom-dwelling) organisms, and were considered responsible for coral mortality that occurred along a 400-kilometer stretch in the Mentawai Islands. During the 2019 and 2020 Australian fires, released iron-rich aerosols initiated a prolonged phytoplankton bloom in the South Pacific Ocean that lasted 4 months, exceeding previous records and generating large carbon fixation.
Quantifying the direct effects on various species, such as fish, corals and plankton, would allow a better understanding of the dynamics of marine ecosystems after fires, thereby broadening the spectrum of analysis and opening up the possibilities for increasingly differentiated studies. It would also be important to delve deeper into the functional and adaptive responses of the different species that occupy these habitats to better understand the mechanisms that maintain biodiversity in fire-prone marine ecosystems. Such research is essential to guide conservation efforts and recovery strategies for these ecosystems, as well as to assess the potential of the oceans to mitigate wildfire emissions.
Oceans: sinks for forest fire emissions
Approximately 6% of the carbon sequestered in marine sediments is of pyrogenic origin, that is, from carbonized compounds generated during fires that flow from the soil through rivers to reach the oceans. "The deposition and accumulation of these compounds have significant implications for the carbon cycle, functioning as a geological carbon sink over long periods of time," says Pausas.
Quantifying the role of marine microbes and phytoplankton in sequestering carbon emissions from wildfires is also a crucial but underexplored area of research. Delving into this area would not only improve the understanding of global biogeochemical cycles, but would also help fine-tune the global carbon balance. "It is essential to integrate this aspect into global carbon models and, at the same time, improve our ability to quantify the transfer of carbon to the ocean through runoff and sedimentation," explains Rodrigo Riera, BIOCON researcher at the ECOAQUA Institute of the University of Las Palmas de Gran Canaria.
For all these reasons, "we must address the ecology of fire in the marine environment to understand in depth the impact of wildfires on our planet. This would enrich our knowledge of the interconnected systems that make up the Earth," concludes Pausas. Within this framework, fire ecology in marine systems is an area of research with great future projection.