Brazil: More about our work on bromeliad food webs…

Now that Juliana’s experiment is finished (for now, a second one is coming), lab work starts. There are several analyses that Juliana needs to run on her samples to be able to understand how light availability affects food webs and energy pathways. On the right, Juliana and I very focused on sorting invertebrates for community and stable isotope analyses!

Now it is time to start our sampling of urban bromeliads! Because urban bromeliads are exposed to increased temperatures and pollution, we want to explore their invertebrate diversity and stoichiometry. Bromeliads are commonly planted in public and particular gardens all around Brazilian cities because of their great beauty, which provides a great opportunity to study the dynamics of these systems in urban centers. 

We know that in natural areas bromeliads host a large diversity of invertebrates, but we don’t know much about the organisms living in urban bromeliads. Because bromeliads are container-inhabiting mosquitoes (and many other invertebrate species) we decided to sample bromeliads in Petropolis, a city north of Rio, which is also known as The Imperial City in honour to the last Emperor of Brazil (Pedro II). Here is Vinicius and Juliana sampling bromeliads in an urban park in Petropolis. After this sampling, we come back to Rio with our “combi” full of bromeliads, which were used by Vinicius student, Nicholas Marino in a experiment focused on modelling water dynamics in the tanks of bromeliads. 

After Petropolis, we sampled bromeliads in Rio do Janeiro. Within Petropolis and Rio we find some areas that are more urbanized than others, and this could help us to understand the community structure and the stoichiometry of these aquatic systems along gradients of urbanization. On the left, you can see Vinicius and Juliana sampling invertebrates in a “Carioca” Bromeliad.

After identifying the invertebrate species we find in these systems, we will run chemical analyses on bromeliad tissue, tank water, litter, and invertebrates! See how green is the water of these bromeliads, although you cannot see it in the picture, many of these bottles are full of mosquito larvae.

I am very excited about what could potentially be living (beside mosquitoes) in these miniature ecosystems! We will know very soon…

Brazil 2017. Juliana’s big experiment

We just started another exciting field season, this time in Brazil. Juliana S. Leal (PhD student at UFRJ), co-advised by Vinicius Farjalla and Angélica L. González, is taking down her five month-long big experiment, and we are here to help her! Juliana used tank bromeliads as model systems to test the relative importance of autochthonous (primary production) and allochthonous (litter) energy sources to aquatic ecosystems. She manipulated the amount of light bromeliads receive, resulting (we hope!) in photoinhibition or photostimulation of primary production. She will measure responses in the amount of periphyton and filamentous algae produced inside the bromeliad tanks, the decomposition of organic matter, and through the use of stable isotope analyses, she will also determine energy pathways (i.e., autochthonous vs. allochthonous) for the aquatic food webs inhabiting these aquatic microcosms.

Bem-vindo ao Brasil! We started this field trip with a cold beer to cope the heat (~34 Celsius). The initial team is composed by an amazing and fun group of researchers from the “Laboratório de Limnologia, UFRJ.” The ladies in the picture, from left to right are Dr. Aliny Pires, Dr. Lucia Sanches, student Sorana Lima, and Juliana. After this super friendly welcome, I have no doubt that I will have a lot of fun with them.

Juliana’s experiment includes 12 light treatments x 4 replicates in the field (48 experimental units). She performed her experiment in the Reserva Ecológica de Guapiaçu (Regua), which is a beautiful nature reserve of Atlantic forest.

Juliana built mesh cover structures of different density to manipulate incoming light to bromeliads. After running this experiment for five month and allowing insect colonization, we are taking it down! We started collecting samples of water for chemical analyses, algae and periphyton for primary production estimates and stable isotope analyses. Look at Juliana (left picture) pipetting water from one of her treatments in the field.

Back in the lab, there is so much more to do. Juliana (bottom picture) is preparing water samples for water analyses. The picture at the right shows the wide variety of colours in the filters evidencing elemental residues found in the water. These will need to be analyzed for C, N and P contents.

Invertebrate sorting takes a lot of time and patience. We need to separate the invertebrates belonging to each treatment for identification, counting, weighing and stable isotope analyses. Below you see student Natalia Souza going over bromeliad water getting and classifying the invertebrates she finds. 

Our work goes on until very late, no matter how strong is the thunder storm over us! Vinicius and student Carlos Batista joined us, and appear in this picture with Aliny measuring and washing a bromeliad to get its water volume capacity (a proxy for habitat size) and make sure we extracted all invertebrates.  This is just the second day and we have only done 25% of the field work planned, another hard but fun day of work is waiting for us tomorrow, or I should say, in a few hours.