Micro-environmental factors and the endemism of bromeliad aquatic fauna

Abstract

Tank bromeliads harbour aquatic microcosms with many endemic species among their leaves. We performed a set of experiments to determine which factors maintain the bromeliad aquatic fauna in isolation from neighbouring ponds. We cultivated three invertebrates species (an ostracod, an annelid and a cladoceran) from a pond surrounded by terrestrial bromeliads in Southeastern Brazil and introduced them inside cleaned bromeliads, using recipients with the same volume as controls. The pH, conductivity and organism densities were monitored in the bromeliad samples and controls for 41 days. The samples introduced inside the cleaned bromeliads showed a significant decrease in pH and conductivity compared to the controls. The pond organism populations introduced in the bromeliads presented a high extinction rate and a significant population decrease when compared to the ones introduced in the controls. We attributed the population decline experienced by the pond organisms to the oligotrophic conditions generated inside the tanks by the bromeliads due to the nutrient absorption. We suggest that the changes in water chemistry induced by the bromeliads could play an important role in isolating their microcosm communities from other freshwater systems. Other mechanisms that could produce the high rates of endemism in bromeliad fauna are discussed.

Bromeliad tanks are unique habitats for microbial communities involved in methane turnover

“…Also water conditions between bromeliads and nearby located ponds were previously described to be different. For instance, some aquatic invertebrates, like the bromeliad ostracod (Elpidium bromeliarum) were only found in tank bromeliads (Lopez et al 2009), which differ in terms of specific composition compared to nearby ponds and swamps (Little and Hebert 1996). Consistent with our hypothesis, our results indicate that each tank bromeliad creates a unique island in the canopies with respect to its microbial community.…”

“…Along with our hypothesis we clearly observed differences in pH, carbon, nitrogen and oxygen concentration between plant slurries and especially carbon content revealed to be a major determinant for the bacterial, archaeal and methanogenic community composition. Carbon availability was already identified as one of the main drivers of microbial community structure in soil (Fierer et al 2003) and Lopez et al (2009) assumed that occasional organic matter inputs can induce a eutrophic condition in tank-bromeliads. In a previous study by Goffredi et al (2011b) it was shown that pH has an effect on the bacterial community composition and that a low water content and therefore an increased oxygen exposure, affected the bacterial and archaeal community composition in tank bromeliad slurry (Brandt et al 2014;Brandt 2015).…”

Assessing the role of canopy cover on the colonization of phytotelmata by aquatic invertebrates: an experiment with the tank-bromeliad Aechmea lingulata

“…Moreover, the experiment duration was long enough for all taxa present in controls to colonize tanks in both treatments. The absence of differences in most of the ecological parameters evaluated and the dominance of few taxa in shaded and unshaded bromeliads reflect the ecological filters provided by the studied ecosystems (Lopez and Rios, 2001;Lopez et al, 2009;Marino et al, 2012), which selected the colonizing organisms and resulted in communities with similar structure and taxonomic composition.…”

Kazachstania bromeliacearum sp. nov., a yeast species from water tanks of bromeliads

“…Water tanks of bromeliads are dynamic and complex environments inhabited by communities of different organisms including endemic species (Benzing, 1990;Lopez et al, 2009;Whittman, 2000). The presence of trapped water and organic detritus (phytotelmata) in tanks formed in bromeliad leaf rosettes is a major source of nutrients for these organisms and communities associated with the phytotelmata (Richardson et al, 2000).…”