Bats as ecosystem engineers in iron ore caves in the Carajás National Forest, Brazilian Amazonia

Abstract

Ecosystem engineers are organisms able to modify their environment by changing the distribution of materials and energy, with effects on biotic and abiotic ecosystem components. Several ecosystem engineers are known, but for most of them the mechanisms behind their influence are poorly known. We detail the role of bats as ecosystem engineers in iron ore caves in the Carajás National Forest, Brazilian Amazonia, an area with > 1,500 caves, some holding ∼150,000 bats. We analyzed the chemical composition of guano deposits in bat caves, radiocarbon-dated those deposits, and elucidated the chemical mechanisms involved and the role the bat guano has on structuring those caves. The insect-composed guano was rich in organic matter, with high concentrations of carbon, nitrogen, phosphorus pentoxide and ferric oxide, plus potassium oxide, calcium and sulfur trioxide. Radiocarbon dating indicated guano deposits between 22,000 and 1,800 years old. The guano pH was mainly acid (from 2.1 to 5.6). Percolating waters in those bat caves were also acid (pH reaching 1.5), with the presence of phosphate, iron, calcium, nitrate and sulfate. Acid solutions due to guano decomposition and possible microbial activity produced various forms of corrosion on the caveś floor and walls, resulting in their enlargement. Caves with active or inactive bat colonies had, on average, horizontal projections 4.5 times larger, areas 4.4 times larger, and volumes 5.0 times bigger than the reginal average, plus more abundant, diversified and bigger speleothems. In an example of bioengineering, the long-term presence of bats (> 22,000 years) and the guano deposits they produce, mediated by biological and chemical interactions along millennia, resulted in very unique ecological, evolutionary and geomorphological processes, whose working are just beginning to be better understood by science. However, the current expansion of mineral activities coupled with the loosening of licensing and cave protection rules is a real conservation threat to the bat caves in Carajás. The destruction of those caves would represent and unacceptable loss of both speleological and biological heritage and we urge that, whenever they occur, bat caves and their colonies must be fully protected and left off-limits of mineral extraction.

The virome of bats inhabiting Brazilian biomes: knowledge gaps and biases towards zoonotic viruses

“…The majority of studies focusing on Rhabdoviridae , and more specifically on the Rabies virus (RABV), were likely motivated by concerns about fatal spillover events to humans in Brazil once different bat species are described as important RABV reservoir(34–36). Few studies (1-3) have focused on Orthomyxoviridae, Paramyxoviridae, Hantaviridae, Herpesviridae and Adenoviridae ( Supplementary File 3 ).…”

“…We have also found differences in the number and species recorded as positive for a viral infection/exposure. In the review compiled database we found 31 families in 62 of the 95 bat species studied representing 5 of 9 chiropteran families living in Brazil: Phyllostomidae (38), Molossidae (14), Vespertilionidae (9), Mormoopidae (2) and Emballonuridae (1). In the ZOVER database, evidence of infection was recorded for 22 virus families in 58 of 95 bat species.…”

“…In the ZOVER database, evidence of infection was recorded for 22 virus families in 58 of 95 bat species. Here, the bats represent 6 of the 9 bat families recorded in Brazil: Phyllostomidae (24), Molossidae (15), Vespertilionidae (11), Emballonuridae (3), Mormoopidae (3) and Natalidae (1) ( Supplementary File 4 ).…”

“…Bats (order Chiroptera) compose the second most diverse mammalian order with 1456 known species from 21 families (https://batnames.org) which participate in diverse ecological processes such as plant pollination, seed dispersion, soil renewal up to habitat modifications (1). Bats are also reservoirs of a large diversity of zoonotic and non zoonotic viruses (2)(3)(4).…”

The Virome of Bats Inhabiting Brazilian Biomes: Knowledge Gaps and Biases towards Zoonotic Viruses

“…Bats (order Chiroptera ) compose the second most diverse mammalian order with 1,456 known species from 21 families ( https://batnames.org ) that participate in diverse ecological processes such as plant pollination, seed dispersion, and soil renewal up to habitat modifications ( 1 ). Bats are also reservoirs of a large diversity of zoonotic and nonzoonotic viruses ( 2 to 4 ).…”