Palo Verde Marshland – An Introduction

Since my last post: I have been entirely consumed in a rush of activity and schoolwork and lack of internet access that has inhibited my ability to post regularly, but rest assured, that means I have plenty to update on. In short, since leaving La Selva I spent three weeks living with a host family in the neighbor city of San Jose, San Pedro. I attended classes at the Costa Rican Language Academy (highly recommended!). Travelled for one week around the country (to Cahuita and Montezuma) before reuniting with our faithful OTS professors. From there we headed to a research station up in the mountains of Monteverde called San Gerardo, with an unbelievable view of Volcan Arenal.

Now, we are at Palo Verde, the third of three OTS research stations (the other two of which we have already visited: La Selva and Las Cruces), located along the Tempisque River floodplain at the northern tip of the Gulfo de Nicoya, where the Nicoya Peninsula meets the mainland. Unlike the other stations that we have visited, Palo Verde is located amidst a tropical dry forest – six months out of the year the station is engulfed in a dry season and the majority of the trees lose their leaves. We are here in the transition period between the wet and the dry seasons, although the trees have not yet started to drop their leaves. We are visiting in an irregular El Nino year, however, and rainfall has been exceptionally low even through the wet season.

The station is located right at the edge of the Tempisque River floodplain, occasional flooding has created an expansive marsh that is home to a wide variety of waterfowl. Research and conservation priorities at Palo Verde are centered around the marsh, and there are a myriad of interested political and biological issues ripe for study. Of prominent concern is the decreasing frequency of natural flooding and the (supposedly) consequential invasion of Thalia (a native species in the family Marantaceae that has created a nearly impermeable monoculture in the swamp), Typha (cattails), and Eichornia crassipes (water hyacinth – an herbaceous aquatic plant native to Brazil), which has lead to a decline in open water marshland, and a decline in waterfowl. The principal cause of water decline in the Tempisque River which has lead to an altered flood regime is water diversion for rice cultivation upstream of the national park.

Since our arrival here we have had ample time for exploration and adventuring; we are amazingly lucky that these adventures are closely tied to our ecology courses, and we have been able to learn about all of the organisms we encounter while happily tromping around the area. Highlights thus far have included: many encounters with coral snakes and scorpions, faculty-led projects about termite nests and aquatic macroinvertebrate abundance in the rice cultivation canals, daily runs to the tidal Rio Tempisque where crocodiles can be frequently sighted, daily tramps through the marsh, and a hands-on learning experience with bats (mist-netting, capturing, and observing) with a U-Latina biology professor/bat specialist. While all of these experiences are worthy of an independent post, I am limited by free time (not enthusiasm!) and will update more posts with pictures as I find my time. Upcoming posts: explorations in the marsh, and a bat lecture recap.