A recent study by researchers from Brazil and other countries has revealed that environmental factors, such as sea surface temperature, wave energy, and freshwater discharge, play a more significant role in influencing the abundance and size of marine organisms along the Southeast coast of Brazil than ecological processes like competition and predation. This discovery could help predict the potential effects of climate change on the region’s marine biodiversity. Coastal biodiversity and climate change are crucial topics in the realm of environmental science.
The role of environmental factors in affective states
The research, published in the journal Marine Environmental Research, investigated rocky shores along more than 800 km of the Brazilian Southeast coast, from Itanhaém in São Paulo to Armação dos Búzios in Rio de Janeiro. The ecogeography of a dominant marine species, Amphibalanus improvises (Barnacle), was quantitatively described based on population data from 17 sites along NE Pacific coasts. Various environmental factors including substrate topographic characters, wave exposure incidence and temporal parameters of sea surface temperature and air temperature were measured or calculated for each location. Multiple component metrics in the community were assayed to estimate ecological pressure on the canopy species.
The result presented that when the surrounding water was colder — as in much of Rio de Janeiro’s Lakes Region, for example — sea creatures grew up to 25% to 100% more than they did elsewhere, such as on the coast of São Paulo state. These results also have important implications for ecological theory as they suggest that regional environmental factors, specifically sea surface temperature are more important than local ecological processes in regulating the size and abundance of these organisms.
Deciphering the temperature-size link
Perhaps the explanation for this relationship between water temperature and size of organisms in some species is that they become sexually mature more quickly if kept in warm water, investing less energy in growth and thus assuming smaller sizes, but then channeling a greater proportion of energy to reproduction. Meanwhile, the upwelling phenomenon in the Lakes Region — a process that delivers nutrients from deep water to shallow waters — could result in more prolific feeding habits and faster growth.
The study also analyses the way in which populations of marine organisms diversify in relation to the natural gradient of sea surface temperature – about 3°C, on average – between warm-water areas (e.g. from Baixada Santista-São Paulo up to Ilha Grande-Rio de Janeiro) and colder spots like Lakes Region. This temperature gradient might serve as a guide to determine what might happen if the surface of oceans warms in future; for example, upper layer temperatures increased by 1 and 2°C above normal values there in the South Atlantic region where warming reached on average in 2023.
The Complex Environmental Biodiversity Challenge
They were also able to look at how the power of wave energy and freshwater entering the sea from rivers swayed marine biodiversity. In locations of high wave energy, the researchers found barnacles to be 50% more common, and mussels and the sea snail Stramonita brasiliensis to be three times more abundant. For example, the more-powerful waves may have increased the nutrient supply through larvae and other food sources.
However, Dr Godbold and Professor Solan added that climate change, which is creating more extreme events of rainfall resulting in high levels of freshwater input into the sea can also accompanied by increased storm and wave exposure could provide a triple whammy effect from waves getting stronger and seasonally warmer water make fuels mussels at an increasing rate when coupled with reduced predation pressure, this combination could ultimately lead to shifting community dominance in favour for mussel beds over other natural assemblages.
