Fish on the move in Costa Rica


During the winter 2016-1 OTS Field Ecology course I confirmed something that I didn’t want to believe: fish are being moved among streams and rivers within Costa Rica.

Peer into a stream in Costa Rica and you’re likely to see a fish community more impressive than anything you’ll see in a freshwater aquarium, but this diversity is under increasing threat from changes to both terrestrial and aquatic ecosystems. One way that streams and rivers are being changed that we know very little about is through species introductions. Commercially important fish species have been introduced into Costa Rica from all over the world, and inevitably a number of these species have escaped culture and established self-sustaining populations. Tilapia (Oreochromis sp.) were introduced from Africa for aquaculture, but some escaped and now wild populations are established in lowland streams and rivers throughout the country (Bussing 1998). Similarly, rainbow trout (Onchorhynchus mykiss), a cold water species native to North America, were introduced for aquaculture at high elevations, such as at the Cuericí Field Station. Rainbow trout are now established in the mountain streams near Cerro de la Muerte (Don Carlos Solano,  pers. comm.). Another growing threat of unknown risk is transplanting native species within Costa Rica.

Costa Rica has a rich freshwater fish fauna that is divided into three different fish ecology provinces (Bussing 1998). Costa Rica’s geological history and unique climate zones have lead to the colonization and evolution of different species on the east and west versants (Figure 1) and unique fish fauna to the north and south. Few species are found in both the north and the south on the Pacific side and even fewer cross the east and the west versants. As a result, each region is home to a number of endemic fish species that are found nowhere else on earth.


Figure 1. Map of Costa Rica showing the divide between the east and west versants. Parachromis loisellei is native to the east including the streams around La Selva. It was recently found outside of its native range in the Rio Rincon and Rio Esquinas.

Now there is evidence that fish species are being moved within Costa Rica. I recently posted a video to the Stroud Center Facebook account of a school of cichlids in the Rio Rincon on the Osa Peninsula in southwest Costa Rica (Figure 2). Bussing (1998) surveyed this river but did not report any large cichlids from it, but he did see Amphilophus (Astatheros) lyonsi in a nearby river. The fish in the video didn’t look exactly like A. lyonsi, but this species was my tentative identification based upon the assumption that it was either missed by Bussing or was a recent colonist from a nearby source population, and that the difference in spotting pattern was a result of phenotypic plasticity. But not everyone was buying it. Someone on Facebook said that the fish in the video was Parachromis loisellei, a species native to the north Atlantic versant of Costa Rica. Indeed, the fish in the video did look more like P. loisellei, but there was no way that species got into the Rio Rincon on its own. Was it really more likely that a species was transported across the country? Without an individual in-hand to confirm the identification it would be impossible to know for sure.


Figure 1. Screen grab of Parachromis loisellei from underwater video taken in the Rio Rincon

I went back to the Rio Rincon the next year and brought electrofishing gear, seines and cast nets, but never saw another mystery cichlid. I was stumped. Fortunately, in the meantime, I came across a fish survey from a tributary to the Rio Esquinas, which is near the Rio Rincon, and wouldn’t you know it, they found P. loisellei (Pichler and Schiemer 2008). I also showed the video to Dr. Ron Coleman from UC Sacramento while at the La Selva Biological Station in northeast Costa Rica during the winter 2016-1 OTS Field Ecology course. Dr. Coleman is an expert on the cichlids of Costa Rica, and he too believed that the fish in the video was P. loisellei or P. dovii, both species that we could see in the streams and rivers around La Selva. Based upon Pichler and Schiemer (2008) there was evidence that P. loisellei had been transported across the country, and now I believe that it was also the species in the Rio Rincon.

What have I taken away from this experience? Humility is just the beginning. Evidence that P. loisellei has been transplanted within Costa Rica raises a number of questions. First, why would someone transport this species? According to Dr. Coleman it was most likely for fishing. I did see people fishing near where the P. loisellei was spotted (Figure 3), but we probably will never know who introduced the species to the Rio Rincon and Rio Esquinas. At the same time, it is unrealistic to expect species transplants to slow or stop without working with people on the ground in the places where introductions are occurring.


Figure 3. Subsistence fishing in the Rio Rincon

As for the impact P. loisellei is having, 12 of 19 Costa Rican endemic fish species live in the southeast near Rio Rincon (Bussing 1998). Species introductions are experiments that are difficult to reverse. Once an introduced species becomes established it may be impossible to eradicate.

I also want to acknowledge how my bias influenced my perception. I didn’t want to believe that fish were being transplanted within Costa Rica, so I proposed what I thought to be the simplest answer. A robust study design that included voucher specimens was critical to allow others to look at the evidence and come to their own conclusion. Pictures and video may not be adequate vouchers for most studies, but in this case they were sufficient for others to evaluate and challenge my identification. Unfortunately, those findings do not bode well for Costa Rica’s native fish fauna.



Bussing, W. A. 1998. Peces de las aguas continentales de Costa Rica (Freshwater fishes of Costa Rica), 2nd ed. Editorial de la Universidad de Costa Rica, San Jose, C. R. 468p

Pichler, C., and F. Schiemer. 2008. Ecology of fishes of Quebrada Negra, Costa Rica, a first order neotropical lowland stream. Pages 495–508 in A. Weissenhofer, W. Huber, V. Mayer, S. Pamperl, A. Weber, and Aubrecht, editors. Natural and Cultural History of the Golfo Dulce Region, Costa Rica. Plöchl-Druck, Werndlstraße 2, 4240 Freistadt, Austria.



Tu-tun-tá!! Dancing in the field


In late XIX century, some student asked to Michael Faraday about the secret of his successful in science. Faraday answered that The secret is comprised in three words – Work, finish, publish“. I believe in the Faraday’s quote, but some of the process to work, finish, and publish need an extra advice; don’t forget having fun!!

Four weeks in a country that perhaps is one of the most recognized by biological studies, visiting mystic and highlight Biological Stations (BS), learning with the most brillant classmates and Faculty, forced my body and my mind to improve my skills in Science, and beyond; overall, it was better than it sounds!!. Let me try to include a brief summary of four chapters in my life; to share my feelings and experience and encourage colleages to apply in this amazing course.

Chapter 1. Palo Verde BS “Let´s dance in the dry forest”


Dry forest at Palo Verde Biological Station

I was affraid; four weeks no dancing, and the first day I had headache for try to understand all in my “second lenguage”?!?! OMG, we need something to remedy this situation. Fortunately, “Ricky” came to save us!!; and he suggested a “Salsa workshop by OAC” after the Stats work. Some of my classmates look around and just they didn’t care about that; we had “R” assignments after take data in the field, and come on! Salsa? Why if we are not in the “latino” course?! Well, although Salsa is traditionally the latino dancing, it borns in New York!! Yeah, with a lot of influences by boricuan music (Puerto Rico), cuban music, but it rise in the Big Apple (as I known in East Harlem; “Spanish Harlem”).

My dad told me that if you take the attention of the 10% of your students, you did an excelent job as a teacher! Well, some of my classmate save my ass such as Salsa instructor, and I take advantage of that in the New Year celebration in Palo Verde, and all the parties coming in the course!!! Please keep dance guys!!!


People dancing in La Selva Biological Station (photos from Palo Verde dancing are not available; sorry, sorry, sorry, sorry)

Chapter 2. La Selva BS “Would you digging my hole? Att. Dipteryx panamensis

Just walking throughout the same trail where walked Holdridge, Jansen, Stiles, Blake, Loiselle, Chazdon, Aide, Wilson and more, if not all, “celebrities” in Tropical Ecology is a real honor. Moreover, try to understand the process behind of all this vast jungle, and understand that all could depend of soil nutrient cycling is fascinating!!!

I have the fortune to be witness of the bat poop (guano) depositation (yeah, they actually poop on me!); and already I know that even that shit (litteraly) supports the fertilization of one of the giants in the forest (Dipteryx panamensis; see Voigt et al. Biotropica 2015), which is the key resource of an endangered macaw species (Ara ambiguus); is that not so cool??!?!

Whould you diggin my hole

I was in the hollow of a Dipteryx panamensis tree, the bats were flying and pooping over me!

There were a suggested idea that hollow trees used by bats in the forest could be contribute to the nutrition budget, as a “hotspot” of nutrients. Actually, it is proved that the same N of the bat-guano fertilized D. panamensis nuts, and finally, I thought, fixed as well in Ara ambiguus tissue!! We performed a sample design to meassure soil nutrien concentration (Nitrate and Phosphate) and pH under and around hollow and no-hollow D. panamensis trees. It was awesome be part of a biogeochemistry project; and known all the complicated but facinating process involved. Work with biogeochemistry supports the ideallistic thought of be a naturalist…

“Do you remember when you were first a child

Nothing in the world seemed strange to you?

You perceived, for the first time, shapes already familiar,

And seeing, you knew that you have always known

The lichen on the rock, fern-leaves, the flowers of thyme,

As if the elements newly met in your body,

Caught up into the momentary vortex of your living

Still kept the knowledge of a former state,

In you retained recollection of cloud and ocean,

The branching tree, the dancing flame.” 

Kathleen Raine

Do you like it?? check out our Science Communication project in La Selva Biological Station with #BlackLlamaFilms, click on The Beauty in BioGeoChemistry

Chapter 3. Cuericí BS “The ‘feathered serpent’, or perhaps a ‘chunky trogon’, await for you…” 

There were a Mesoamerican deity named in Nahuatl language as Quetzalcoatl; quetzalii means beautifull or feather, while coatl means serpent; therefore, Quetzalcoat is like “beautifull serpent” or “feathered serpent”. The Resplandecent Quetzal (Pharomachrus moccino) is perhaps one of the most beautiful birds in Neotropics (well, all birds in Neotropics are beautiful!!), described sometimes simplelly as “a large, chunky trogon”, but it is an excellent example of the magnificent Neotropical biota. This “chunky trogon” is closely associated with the “feathered serpent” deity; so, it was mandatory known this Mesoamerican god in the field by my self eyes!!!

All was prepared to explore looking for the Mesoamerican god Quetzalcoatl in the oak forest. I was hikking mountains that remember me the Andes, my homeland, but in Costa Rica. However, I felt sick and I lost the main hike within Cuericí Biological Station. Don Carlos and Don Alberto (nice guys!!) comfort me, as well as my classmate, so we decided hike before dawn the same day that we leave Cuericí. Nice hike, nice trail, dark and cold dawn; we went in the field Becca, Stephanie, Ingrid and me, and Will joint us later. The dawn chorus was amazing!! but I lost my hopeness to see the mystic quetzal… however, more eyes see more!!! and Ingrid asked for my binoculars to see “something blue just up there”…. OMFG!!!!! it was a fu… serpent with feathers, flying, dancing for us!!! A resplandecent male just flew in front of us, from the first tree to other, and the dancing-long tail claim all the attention in the oak-forest canopy; you can´t imagine our emotion!!!! all the cold was gone, all the sickness gone, all the universe turns in perfect symphony after that sight; thanks Ingrid a lot!!! and the victory shout is… LIFER!!!!! (back to bird-work is amazing, but I lost many birds; I need back to CR!!! eBird List of the dayGreen Violet-ear calling)

Espectograma Colibri thalassinus

Green Violet-ear call (x is time, y is frequency). Recorded with the great-fancy acoustic equipment of Becca (thank you so much Bequita!!) in Cuericí

Chapter 4. Las Cruces BS “What the Ficus?!?!”

One of the big deals in restoration includes attract large frugivores to new secondary forests and active reforestation plots. Researchers in Las Cruces Biological Station, based in the knowledge of rural people, get start to plant big stakes as a way to contributed with the restoration process. Conversely to some traditional restoration projects, which used trees not so attractive or unaccessible to some of those large frugivores (ej. Inga or Erythrina spp), one project in Las Cruces began to plant figs (Ficus spp.) stakes in Young Secondary Forest plots as a strategy to attract large frugivores.

There are more than 800 spp of Ficus worldwide, and different frugivores such as birds, bats and monkeys love them; thus, plant big stakes of Ficus could be support the use of large and small frugivores during several time in the reforestation process. However, variation of the percentage of resprouting (growth of new leaves and branches), and even survivor, among the Ficus spp. planted, give new points of view in the process. For instance, how is the relationship between the wood specific gravity of the Ficus and the resprouting probability?

During our FLP in the course, we conduct a short research leaded by Dr. Leighton Reid, linking the specific gravity of seven Ficus spp. with the resprouting probability. Our results did not yield a strong relationship, but it seems that other things could be envolved. Interesting, two species with free-standing habit (subgenus Pharmacosycea) had less resprouting probability than other five stranglers habit species (subgenus Urostigma); which could be mediated by niche conservatism or life history.


The “What the Ficus” team, at Panama – Costa Rica border

Final comments…

Time was not enough, never it is! But my aim with this post is just give a brief opinion about a experience that changes the live. Pura vida, mae!!

Thanks to all, my classmates, the Faculty, OTS and the wonderful Biological Stations; I will back, for sure!!

OTS give to me a course tuition scholarship (OTS membership institution), and a course tuition award (OTS graduate tuition aid). On the other hand, UPR give to me four course travel awards to attent the course (Natural Science Faculty, Department of Biology, Dean of Graduate Studies and Research – DEGI, Dean of Students), and the Graduate Program offers an extra aid (noticed post course). Thanks of all these aid, I could attent the course and explore my potential with OTS.

Every day, I will try to work, finish, hopefully publish, but sure I will trying to keep having a lot of fun!!!

The Conservation Conversation or “Find your inner Don Carlos”


On our final night in Cuerici, we circled in the wooden classroom, our backs half heated by the fire. Don Carlos: expert survivalist, trout farmer, Latino Buddha, sat serenely ready to field our questions. His comrade, Alberto, was perched on the edge of his seat, full of grit, quick words, and anecdotes of rebellion. These men, juxtaposed in mannerism were united by a goal: to conserve and protect 200HA of secondary and primary oak forest near Cerro de la Muerte, Costa Rica.

oak forest 7

The primary oak forest. Photo by Nick Herremann.

Conservation was the discussion  topic and we began asking Alberto and Don Carlos questions about their lives, their choices, their struggles. Our coordinator, Andrea, did her best to translate. Both men had started as hunters, with little care for the land and are now living in dedication to this plot, raising trout, giving tours and hosting classes to keep it all aloft.

“Have any government programs or initiatives been helpful to you?” we asked.

“No,” said Don Carlos.

“How did you transition from being a city planner to working here?” we asked Alberto.

He launched into a rapid-fire, 5-minute, soliloquy (in Spanish) complete with hand gestures and some yelling. The gist being that once he felt ready to kill someone, he gave it up. I think a lot of that rant was lost in translation. Andrea giggled.

At the end of the conversation, Will asked Don Carlos, “Is conservation something you can do alone?”

I readied myself for a formulaic answer; we need each other, no man is an island, we stand on the shoulders of giants, etc., etc. But Don Carlos looked straight ahead with a solemn face and said in a quiet, steady voice, “Yes.”

The moment lingered, and then a voiced chimed in, “if you are Don Carlos!”

We laughed together. Yes, according to Don Carlos, conservation is something you can do alone. And this gave me hope.


Don Carlos looks out over the trout ponds and talks about his land.

A few years ago I was commissioned by to write a series on “Innovation in tropical forest conservation.”  For this job I was fortunate to interview 30 “change-makers” about their work in tropical forests. I noticed some themes. The primary theme was this: real change seems to happen when a small group of people or even an individual dedicates themselves to one place or cause for a very long time.

This is not really a revelation. The idea of success via life-long dedication applies across fields and professions: academia, athletics, art, music, etc. The “problem” for most of us in the room and many in our generation is deciding where to focus our passion, talents, energy and intelligence. We feel we can do almost anything and the effect is paralyzing. What do we choose? How do we know it will be effective? Will it be meaningful? We discussed this at length and tears were shed.

And after the conversation, I’m not sure we had any more clarity. But I do I think we touched upon some important points. The first was to accept that you can NOT do absolutely anything. You are not going to be good at whatever you want. Accepting this is actually a bit of a relief. You don’t have to be an astronaut, and Olympic gymnast and save the rainforest. Phew!

So, what are you good at? And of those things, what makes you happy? Because, and this I feel was the second point, it is difficult to sustain a lifelong effort if you are miserable. Marshall Thurgood (African-American author, philosopher, and Civil Rights leader) sums this sentiment up more beautifully than I:

“Don’t ask what the world needs,” he says. “Ask what makes you come alive, and go do it. Because what the world needs is people who have come alive.”


Often my memories, before they start to fade, brighten and crystallize.  So now, as I reflect on the OTS course and my 11 fellow travelers just a few weeks out, I remember more clearly the gifts they have to offer the world, their brightness and their joy as they worked directly with their strengths and passions.  I hope they can hold on to that same image of themselves. I hope they remember what it felt like to be so alive.

Exploring a New World: The Tropics



By: Shaniqua Gladney

Exploring the tropics was like being in a new world that I never thought I step foot in. When I first arrived at in Costa Rica, I was expecting a jungle with wild animals swinging from every branch in sight. I expected downpours of rain every hour of the day.I thought that I would fear for my life from being devoured by a wild beast or taken down by a venomous Fer-de-lance. I was sure that my eyes couldn’t see beyond the camouflaged dangers that lies withing the dense jungle. I was so sure that I would not return to the US until I met my fearless OTS leaders. They ensured us that no one would die on this trip and there would be lots of learning and great fun.

Each and every site from Palo Verde to Las Cruces not only taught me something new about…

View original post 195 more words