An Ocean of Data Stories around data, the people who collect it, and how it's used
Bromeliad Borne: Data between the leaves of a miniature aquatic ecosystem
19 March 2019 Alathea

Trudging through the restinga* in southern-Brazil requires a suite of accompanying equipment. Full body coverage is necessary to stave off clouds of mosquitoes roving the forest: A mosquito jacket (though smaller biters may still get through), rubber boots (protection from snakes and torrential rains), and leather gloves (to avoid bromeliad-induced body piercings).

The author suited up (left); A path through the bromeliads of the Brazilian restinga (right)

Far from the "big data" gold available in many fields these days, bromeliad data is collected with intense physical labor. Datasets are built up in amounts that can be digitized manually. Each bromeliad is essentially a bowl of standing water, available for insects to deposit eggs within its leaves. Bromeliads are found in low nutrient areas (sandy soil, or tree branches), where they obtain nitrogen via the creatures that inhabit them: insects and other invertebrates that process leaves releasing the nutrients locked within. Data collection usually involves removing bromeliad water with a turkey baster, sifting out the large detrital matter, then sorting through the invertebrates. Every individual of every species is identified with the assistance of a dissecting scope or hand lens. By completely censusing the organisms in bromeliads around a particular site, ecologists can ask questions about the factors that determine which species live where.

Bromeliads are often thought of in their epiphytic variants - blanketing tree branches in the rainforest and providing fodder for the 1992 film Medicine Man. In the southern Brazilian restinga, the bulk of them are of the terrestrial species Quesnelia arvensis, and cover the sandy forest floor, where they protect themselves with punishingly sharp leaf tips and saw-toothed leaf edges. They are home to lots and lots of species of fly larvae, as well as damselfly nymphs, leeches, aquatic beetles, ants, spiders, and sometimes frogs. In turn, they provide food in the form of adult flies to a host of birds and other insectivores living in the forest.

Q. arvensis top view and close up of defenses

In spite of the relative difficulty in obtaining data from these plants, it is the presence of fairly clear habitat borders that makes bromeliad research a joy. While other wildlife biologists may need to rely on mist nests, camera traps, or tagging to document their ecosystem, the bromeliad can have its entire community removed, identified, and even returned home if desired. Such a thing is neither feasible nor ethical when one is studying birds, mammals, fish, or most other animals. Even insects in non-contained habitats present sampling problems.

Since a single bromeliad researcher can only gather small amounts of data at a time, the key to generating interesting and generalizable results is collaboration. Bromeliad habitat is studied by an international group of researchers, The Bromeliad Working Group, who collect data from field sites spanning the neotropics. Data collected from a single field site has limited potential for interpretation - conclusions can only be drawn about the study site in question. With this collective data, broader questions about the bromeliad ecosystem can be discussed. For example, researchers can start to understand how the environmental variables may influence which species are colonizing the area (1, 2) and even the physical characteristics that determine those differences (3).

The Bromeliad Working Group database grows every year as researchers collect more information from more sites. It is still with old fashioned field work and collaboration that our understanding of the environment and the species that live on this planet, continues to grow.

Data Vignettes, Ecology

An Ocean of Data is a collection of stories investigating how researchers and organizations use data to further their work. It is written by Alathea Letaw, founder and data scientist at Lutris Analytics in Spokane, WA.

Lutris Analytics provides data analysis and visualization services to non-profit organizations and researchers.

Alathea is an alumnus of the University of British Columbia where she earned her doctorate in Ecology.

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