Rodolfo Silva, “Doctor Worm,” studies the biodiversity of marine communities by looking at their various dimensions

Art by Julia Jabur

By Meghie Rodrigues

As a child, Rodolfo Silva would conduct small experiments with ants. “I would put an ant in a bottle cap filled with alcohol or perfume,” he explains. He wanted to observe how the insect would react. “Then I would rescue it by washing it in a pot of water and blowing it dry to keep it alive.” For young Rodolfo, these experiments weren’t about harming the ants (some didn’t die), but rather about curiosity. “Kid stuff, you know? It made me feel like I ruled the world.” 

Nearly two decades later, Silva earned a degree in biology from the Federal University of Alagoas. From Grota do Cigano, a working-class neighborhood on the outskirts of Maceió, he went on to pursue a Ph.D. in evolutionary biology at the Federal University of Rio de Janeiro. Life wasn’t easy, and studying was the only way out. “When you come from a background of scarcity, you seize every opportunity that comes your way,” he says. By then, his focus had shifted from ants to worms – specifically, plolychaetes, marine bristle worms.

In addition to serving as a food source for fish, benthic worms—those that live on the ocean floor—are highly effective at converting organic matter into animal biomass, which consists of the remains of these organisms and is used to generate energy. By burrowing through the sand on the seafloor, they enhance the oxygenation of the sediment-rich environment they inhabit. During his Ph.D., Silva studied the diversity of worms on islands such as Fernando de Noronha and the Rocas Atoll. 

Until then, only five species were known to inhabit this type of environment. He increased the count to 44. Of these, twelve were previously unknown to science, and three of the species he described stand out: Branchiosyllis belchiori, Branchiosyllis gonzaguinhai, and Salvatoria marielleae. The scientific naming of these annelids honors the singers Belchior and Gonzaguinha, as well as the councilwoman Marielle Franco, who was killed in 2018.

The names made their way onto a popular scientific etymology board on social media. The worm named after Marielle Franco sparked considerable controversy. “It generated ridiculous hate speech,” the biologist explains. “Many people sent me messages questioning why I was mixing science with politics and suggesting that I should suffer the same fate as her. I received many absurd messages.”

His fascination with marine worms—which earned him the nickname “Doctor Worm” from his friends in the Rio de Janeiro maracatu group Baques do Pina—goes far beyond understanding their diversity. In his postdoctoral research at Fluminense Federal University (UFF), Silva seeks to study this group of animals to understand what determines the dimensionality of biological communities, using marine communities along the Brazilian coast as a model. 

In ecological studies of biodiversity, dimensionality is an emerging concept that characterizes communities of animals, plants, and microorganisms. It refers to the different “dimensions” or aspects by which a community of different species can be described. 

“We take a sample from a community and count the number of individuals in that sample, known as abundance,” Silva explains. “Next, we count the species within the sample to assess species richness, another measure of the community’s biodiversity.”

The distribution of individuals of different species in a sample provides valuable insight into the diversity of a community, offering an alternative perspective on biodiversity. The array of metrics available to assess community biodiversity seems almost limitless, ranging from physical and functional traits of species to their environmental interactions. “Paradoxically, however, the more metrics we calculate, the greater the risk of fragmenting the unified concept of biodiversity,” observes Silva.

Silva is trying to determine which biodiversity metrics are correlated and which provide more comprehensive insights into biodiversity. “The degree of correlation between these metrics will dictate the number of dimensions required to effectively assess biodiversity,” he explains.

“If species richness behaves differently from the richness of the community’s functional traits, then we gain insight into complexity,” he says. This is because if these two metrics are correlated, or “pointing in the same direction,” they essentially convey the same information about the community, reducing its dimensionality. 

The higher the dimensionality of a community, the more attention and protection measures it may require. Studying dimensionality can help inform conservation policy in a more comprehensive way than current approaches. “When you look at dimensionality, you look at the characteristics of the community. A more dimensional community contains more information that requires protection and conservation,” he explains.

Dimensionality varies throughout space, and some communities are more dimensional than others. The puzzle is to understand which elements govern dimensionality in different environments, such as the ocean. 

The concept of dimensionality in ecological communities dates back to 2014, but much remains to be understood. “An important study on bats found that their dimensionality was higher in tropical regions and lower near the poles. However, a recent study of sharks found an opposite pattern: dimensionality was higher near the North Pole and decreased southward. We still don’t know why this is the case.”

The hope is that invertebrates, like worms, will help us find answers. “These organisms are small and live in very close contact with the seafloor, so even the slightest variations can impact their community structure,” says Silva. The plan is to compare DNA analyses of species—examining their genetic dimension—with their morphological and physiological characteristics, as well as their functional traits, and their relationships, which represent their phylogenetic dimensions. This research will stretch from the coast of Oiapoque in Brazil’s far north to Barra do Chuí, in the southernmost state of Brazil, Rio Grande do Sul. 

This work focuses on taxonomy and marine ecology. “To conduct research on ecology and biogeography, and to extract chemical compounds for drug development, it is essential to identify the species, its name, and its distribution. All of this relies on systematic taxonomy,” says Silva. 

This work is more significant than it might appear. “Zidovudine, or AZT, the first compound used to treat the HIV virus, was derived from a sea sponge. This discovery was only possible because someone had previously identified the sponge, named it, and documented its location,” Silva explains. “Although taxonomy is not very hot, it remains extremely important.”

This text was originally publicated on Serrapilheira’s Ciência Fundamental blog on Folha de S.Paulo