For many organisms, the species richness That is old man close to the equator, that is, in low tropical latitudes. It is believed that this pattern is related to the intensity of interactions between them, such as the predation and the competition.
ecologists and naturalists suggest that reach their maximum point near the equator and decrease towards the poles, and that the intensity in interactions drives variability in species distribution and richness. However, empirical support for this hypothesis has always been limited.
Now, a new study carried out in two oceans and a very wide latitudinal range reveals that warmer seas Harbor higher predation rates of fish than those in cold water.
The results suggest that climate warming can have a predictable influence on the to control bald (‘top to bottom’) of marine communities close to the coast.
Inside ecology the concept of regulation bald refers to the processes by which predators can cause changes in the populations of their prey. These changes in predation intensity they can determine modifications, both in types and in their relative abundance. For example, if predators are particularly active in this regard, a reduction in the number of prey or its behavior can be changed.
The authors of this article describe that such large-scale changes in ‘top-down’ control may have far-reaching consequences.
Gail Ashton inspects marine invertebrates attached to a panel that was submerged in San Francisco for 3 months. / Smithsonian Institution
A study along more than 10,000 km of coastline
To test whether predation on deep-sea communities is greater near the equator, the researchers fitted a standardized experiment and they have replicated in 36 places along the Pacific and Atlantic coasts of the Americas. The latitudinal range covered is 115 degrees, which corresponds to more than 10,000 km.
In research, which publishes Science, A number of American institutions have been involved in assessing the impact of fish and other predators on invertebrate populations in the seabed.
The studies available to date covering various habitats and large spatial scales provide an conflicting empirical support.
As Gail Ashton, researcher at Smithsonian Environmental Research Center and first author of the study: “No survey in the marine environment has covered 115 degrees latitude. Furthermore, these works, in general, focused only on measuring predation, and not on its consequences on prey populations.”
The strength of this research is the geographic range: 115 degrees of latitude in two ocean basins. A network of 36 sites performing the same experiment
As a result, until now very little was known about how predation affects the composition of prey communities on a large scale.
“The strength of our research is the geographic scope: 115 degrees latitude in two ocean basins; and continues: “A network of 36 sites carrying out the same experiment is a huge undertaking and was only possible thanks to the coordination of a network of qualified marine scientists in the Americas,” continues Ashton.
Marine invertebrates in a panel protected from predators by cages during the 12-week experiment on the left and an unprotected panel on the right. /Zvi Hoffmann
Warming alters interactions between species
The researchers observed that in warmer tropical waters Closer to the equator, predators have higher rates of consumption and also stronger impacts on the composition of marine invertebrate communities. This refers both to species that make up these populations, such as the biomassthat is, the number of living organisms present.
“O temperature of the sea is not linearly related to the latitude. For example, marine communities that are at 40 degrees latitude experience a different temperature depending on whether they are on the Pacific or Atlantic coast, in the northern or southern hemisphere,” explains Ashton.
The researchers used statistical models to test whether latitude or water temperature better predict the effects of predation on prey communities. Based on their findings, observed trends in predation and its consequences are more strongly related to water temperature than latitude.
“It seems obvious, since most of the biological processes they are temperature controlled. But without analyzing it, another variable more related to latitude could have been more important, such as the energy of the sun or the length of the day”, adds the scientist.
Based on these findings, it is likely that the ocean warming associated with the climate crisis increases the pressure of predation on marine ecosystems.
“The biggest consequences can be in waters with summer temperatures close to or below 20°C, where predation is currently one of the ecological pressures smaller, but it should increase in the future”, he emphasizes.
Furthermore, “there is also implications for fisheries of predatory fish. The current relationship between fishing, predators and prey will change in ways unknown in the future. We now have a better understanding of how dynamics can change, but there are still many factors and interactions that we don’t understand.”
Reference:
Ashton et al., Predator control of marine communities increases with temperature at 115 degrees latitude. Science