Environmental disaster may have affected barely known marine animals

A toxic mudslide released by the collapse of an iron ore tailings dam in Minas Gerais State, Brazil, may have caused the disappearance of species such as a rare sea jelly, researchers warn.

By Elton Alisson  |  Agência FAPESP – The environmental disaster caused by the November 2015 collapse of a tailings dam near an iron ore mine in Mariana, Minas Gerais State, Brazil, was lethal to many known species of plants and animals but may also have affected a vast array of barely studied marine organisms that inhabit areas flooded by the toxic mudslide.

One of these organisms is the extremely rare sea jelly Kishinouyea corbini Larson. The only known established population of this species in the western South Atlantic inhabited Praia dos Padres, Aracruz, Espírito Santo State, an area swamped by the plume of pollutant-filled sludge.

“This species is emblematic of the damage done by the disaster in terms of the loss of information about many marine animals that have never been properly studied, as well as others that may be completely unknown,” said Antonio Carlos Marques, a professor at the University of São Paulo’s Bioscience Institute (IB-USP) and head of its Center for Marine Biology (CEBIMar), in an interview with Agência FAPESP.

Marques and Lucília Souza Miranda, a postdoctoral fellow at IB-USP with a scholarship from FAPESP, have published a paper in the journal Biota Neotropica calling attention to the hidden impact of the environmental disaster on Brazil’s marine fauna and highlighting the example of K. corbini.

This unique sea jelly lives with its mouth upward to capture food, whereas most sea jelly species have downward-pointing mouths. It does not swim but lives attached to the seabed or to some other organism by a peduncle. K. corbini was the first species of Staurozoa to be recorded in Brazil, precisely off the coast of Espírito Santo.

Staurozoa are a class in the phylum Cnidaria, which includes the stalked sea jelly. Marques proposed the class more than ten years ago. It is considered highly important in the evolution of Cnidaria, which includes medusas, polyps, sea anemones, the Portuguese Man-of-War (Physalia physalis), soft and hard corals, and freshwater hydras. Staurozoans are believed to be among the first animals to have evolved in the oceans.

According to Marques, an animal similar to K. corbini may have been the first medusa among the Cnidaria. “Staurozoa are a small class comprising some 50 species, most of which occur in polar and temperate waters,” he said. “Only two species occur in tropical areas of the western South Atlantic, and one of them is K. corbini.”

Although these tiny benthic stalked sea jellies live in the intertidal zone, they are hard to find and are often camouflaged in marine algae. Occurrences have been recorded in the Caribbean, more specifically in Puerto Rico and Mexico.

There is a record of K. corbini in the Abrolhos archipelago off the coast of Bahia State, Brazil, but it has never been seen there again. Part of the area has probably also been affected by the Mariana environmental disaster.

The only known population in the western South Atlantic lived on the coast of Espírito Santo. “As part of a group mostly found in cold waters, with only a very few species in tropical waters, the population found in Espírito Santo must have a unique evolutionary history in terms of physiology, ecology, and interactions with other organisms in a tropical environment, which is quite unlike the ancestral environment in which it originated and developed,” Marques said.

“If this population has been destroyed, which seems highly likely, we have lost all these peculiarities, which could have provided important and unique information about the group’s chemistry, morphology and ecological context, helping us understand more about life in ecological niches affected by climate change.”

The molecular identity of these animals found on the coast of Espírito Santo had recently been studied by Miranda in his PhD research, also supported by a scholarship from FAPESP, but as yet there has been no information on trophic relationships (prey and predators), and it was not known whether the populations recorded were isolated or interdependent, making it even more difficult to estimate the effect of an impact of the magnitude of the Mariana environmental disaster.

“It’s as if several pages that are crucial to the understanding of a book had been torn out and from now on we have to read it without access to these essential passages,” Marques said.

Incalculable damage

According to Marques, who is conducting research in partnership with colleagues in Argentina and with FAPESP’s support, as well as leading a Thematic Project on diversification patterns and processes in cnidarians, it is not yet possible to estimate the damage done to the population of K. corbini that inhabits the coast of Espírito Santo by the flood of toxic waste from Mariana because sporadic mud spills continue to occur. The contents of the burst tailings dam initially surged approximately 650 km along the Doce, one of the most important South American rivers, causing massive mortality of its biota, most of which was buried or suffocated by the toxic sludge.

“Many animals, algae and plants will obviously disappear as a result of the formation of thick sediment deposits because they weren’t equipped to deal with catastrophes of this magnitude,” Marques said. “The Mariana environmental disaster is comparable to volcanic eruptions on small islands, which destroy a vast array of species living in the vicinity.”

The real extent of the damage cannot be gauged because the process is ongoing. The region affected will therefore have to be monitored for many years, including through surveys and comparisons at regular intervals, to understand the resilience and recoverability of the marine and continental environments alike.

“The area of the Espírito Santo littoral zone affected by the toxic mud from Mariana contained a huge diversity of cnidarians, with large populations of several species,” Marques said. “The marine substrate was occupied by several species called builders, such as soft coral, rhodoliths and other coralline algae, which create specific environments for the existence of other species.”

According to Brazil’s main environmental agencies, IBAMA and ICMBIO, by January the mud had affected a total of almost 7,000 square kilometers along the coast of Espírito Santo and may have reached Abrolhos, a coral reef region and one of the most biodiverse areas in the South Atlantic.

“For some time, we’d been monitoring cnidarians in the region and performing genome and transcriptome studies to find out how their DNA was responding to the environment in comparison with cold-water animals. However, now all these research possibilities have been lost, perhaps permanently,” Marques said.

In his opinion, the Mariana disaster is not an isolated case, but a consequence of mismanagement of the environment and marine conservation by Brazilian society.

“The disaster demonstrates the lack of importance given to sustainability and environmental conservation, which will be vital in future,” he said. “It reflects the inappropriate environmental policies in place. They must be improved at every level.”

The article “Hidden impacts of the Samarco mining waste dam collapse to Brazilian marine fauna – an example from the staurozoans (Cnidaria)” (doi: 10.1590/1676-0611-BN-2016-0169) by Marques and Miranda can be read in the journal Biota Neotropica at www.biotaneotropica.org.br/v16n2/en/abstract?point-of-view±bn00216022016.