A combination of three phenomena is increasingly threatening ecosystems in the southern and equatorial regions of the Atlantic Ocean — marine heat waves, high acidification, and low chlorophyll concentrations.
Before 2016, it was uncommon for these factors to converge. Since then, they have been observed simultaneously every year. The three phenomena derive from the current climate emergency.
The ocean is one of the planet’s main climate regulators. It absorbs about 90 percent of the atmosphere’s heat and 30 percent of carbon dioxide. When atmospheric heat is excessive, the ocean overheats. The accumulation of carbon dioxide makes the water more acidic.
These events could be mitigated if the food supply for marine species were adequate. Some ecosystems can survive warmer and more acidic waters if food is available.
However, with very warm waters, there are fewer gases that serve as nutrients for microscopic algae — the base of the ocean’s food chain. This increases the mortality risk for marine species and harms the sustainability of fishing and marine aquaculture.
The increased occurrence of these three factors makes ecosystem recovery impossible, as a minimum time is needed for regeneration to occur.
The Study
The study was published in the journal Nature Communications and conducted by researchers from the Federal University of Santa Catarina (UFSC) and the National Institute of Oceanographic Research (INPO).
The data cover 1999 to 2018 and were collected via research satellites. Six regions of the South Atlantic were assessed, considering their high biodiversity and biological productivity.
The studied locations are the Western Equatorial Atlantic (near the Brazilian Northeast coast), the Western Subtropical Atlantic, the Brazil-Malvinas Confluence, the Gulf of Guinea, the Angola Front, and the Agulhas Current (which connects the Atlantic and Indian Oceans).
It is estimated that these areas account for the fishing of eight million tons of marine life per year, which sustain coastal communities in South America and Africa. The food security of South American and African countries is directly impacted.
Researcher Regina Rodrigues, from UFSC and INPO, states that research on these phenomena can help formulate policies and make more informed decisions about the oceans.
“Marine ecosystems are under pressure from different types of pollution — chemical waste, agricultural waste, pesticides, and untreated sewage, not to mention illegal fishing, which occurs at a faster rate than species can reproduce. We must create more conservation areas and regulations to alleviate these pressures on ecosystems. Ocean warming and acidity cannot be resolved now; they require broader measures to reduce greenhouse gases,” she stated.
Source: Agência Brasil