MG Study Travel Program, Costa Rica 2016 Feb 22 – Floating to Tortuguero On our first day of the 2016 MG tour of Costa Rica, we left the big city of San Jose up in the mountains of the central valley, drove across the Continental Divide, and down the Atlantic slope to the Caribbean lowlands. We went from the lush rainforest of Braulio Carrillo National Park at the top of the Central Volcanic Mountain Range down to open pasture, banana plantations – stopping briefly at the edge of one field to look at the plants and bagged fruits – Driving through Braulio Carrillo National Park. Banana plantation (L), inflorescence (LC), flowers (RC), and bagged fruit (R). and other agriculture on the flat lands, to eventually arrive at the landing spot for boat transportation to our lodge in Tortuguero. This small town on the edge of one of the most remote and pristine parks in Costa Rica, Tortuguero National Park, is accessible only by boat or air. This coastal area of northern Costa Rica and adjacent Nicaragua is a low alluvial floodplain with permanent or seasonal swamp forests in the lowest and flattest areas. This was once an archipelago of volcanic islands until alluvial sediments from the interior mountains filled in the spaces and formed an extensive network of marshy islands interspersed by natural freshwater creeks, canals and lagoons, forming the flooded forest. After we were settled in the long, flat boat our captain navigated the shallow water of the tidal canal, slowing to maneuver around submerged obstacles, and speeding up in straight spots. We plied the chocolate brown waters snaking through rainforest of stunted trees and tall palms. The group in the boat (L) and heading through the brown water (R). Huge raffia palms (Raphia taedigera) draped their long fronds in graceful arches nearly to the water in many places, with other interesting vegetation including many Heliconia pogonantha with pendant red inflorescences, white‐flowered anthuriums, and tall trees sticking up way above the others. Around one curve after another we went in the narrow channel, with brown sandy banks in many places, until we arrived at the big Tortuguero River, and after negotiating a very shallow spot – it was at low tide – we zoomed off toward the village of Tortuguero. There was similar vegetation on this wide channel of muddy‐looking water, but here we started passing docks of resorts, small homes, and a few of the long open boats the local use (as opposed to the covered boats for transporting tourists). Raffia palm (L), blooming Heliconia pogonantha (C), and the Tortuguero River. We arrived at Mawamba Lodge about an hour later, situated on a narrow strip of land between the river and the ocean. We could just see – but definitely hear the roar of – the surf pounding on the beach just on the other side of the park‐like plantings of the lodge. After lunch and a quick dip in the pool for some, we headed out on our afternoon excursion to town to visit the Sea Turtle Conservancy (STC) (http://www.conserveturtles.org/). A big attraction of Tortuguero for many people is the turtles. The coastal zone of the National Park, which has a sandy beach nearly 22 miles long, is the second largest green turtle (Chelonia midas) nesting beach in the world. Leatherback (Dermochelys coriacea) and hawksbill (Eretmochelys imbricata) turtles also nest on the beaches here. The nesting season for green and hawksbill turtle’ runs from July to October with the peak in August, while the leatherbacks nest from February to April. The females come up on the beaches at night to lay eggs well above the high tide mark. The eggs incubate in the warm sand for 7 to 10 weeks before hatching. After the hatchlings dig their way to the surface they have to run across the beach to the surf, usually under the cover of darkness. A guide is required to visit the beaches at night (no one is allowed on the beach unaccompanied after 6:00 pm). STC is the world's oldest sea turtle research and conservation group founded in 1959 by world‐renowned sea turtle expert Dr. Archie Carr to save sea turtles from eminent extinction through rigorous science‐based conservation. The organization, headquartered in Florida, carries out worldwide programs to conserve and recover sea turtle populations through research, education, advocacy and protection of the natural habitats upon which depend upon. STC focused on sea turtles for its conservation efforts in part because these ancient creatures are among the most important indicators of the health of the world's marine and coastal ecosystems. We learned about these animals, the importance of Tortuguero as a nesting site, and how the attitude of the locals has changed from using the turtles for food and other destructive uses, to conserving them as part of their natural heritage and basis for ecotourism. Kari and Gustavo impersonate sea turtles (L); guide Gustavo tells the group about sea turtles (R). After that we took the sandy trail just off the beach to the small village of Tortuguero, walking the one main street – with a tiny church, rustic police station, a little grocery store and a number of small souvenir shops – admiring the various ornamental plants growing there. The village of Tortuguero (L); Bixa orellana (achiote or annato) with pink flowers, red seed pods and dried brown seed pods (C); and flowering Clerodendrum paniculata (R). Feb 23 – Exploring Tortuguero National Park This morning’s activity was an excursion to Tortuguero National Park. Over 77,000 acres was declared a National Park in 1970 after being protected as a turtle nesting sanctuary since 1963. The park has great biological diversity and ecosystems including tidal mangrove swamps, rainforest, beaches, and lagoons, with more than 400 species of trees and about 2,200 species of other plants. The trees here are shorter than those of non‐flooded forest because of the instability caused by the wet, poorly drained soils. Along the coast the forests grade into mangrove forests, and estuary, beach and marine habitats. The lowland flooded forest of Tortuguero The only way to tour the Park is in a boat, and we had to stop at National Park can only be explored by boat. the Park Office first to pay the entrance fee. While Gustavo was doing that, we looked at some of the floating aquatic plants, including water lettuce (Pistia stratiotes), water pennywort (Hydrocotyle sp.), and something else none of us knew that had interesting sausage‐shaped air bladders underneath to keep it afloat. The Park Office (L), water lettuce (LC), and an unknown floating plant (RC) with white bladders to keep it afloat (R). After Gustavo purchased our entrance tickets, our boat captain Hancy took us across the river to enter the systems of natural and a few man‐made canals that form a network through the area to look for plants and wildlife. One of the first things we encountered was Pachira aquatic. This is one of the most conspicuous trees along the Tortuguero canals, but it occurs in many other wet areas from southern Mexico to Peru and Brazil, as well as being cultivated in some other regions in the world—with many common names including malabar chestnut, provision tree, and money tree. It has a buttressed trunk, growing up to 60 feet tall, with palmate leaves on long petioles, and dramatic flowers with white, strap‐like petals and numerous long red stamens. We only saw a couple of the flowers, but many of the rounded, reddish‐brown fruits which can grow up to 12 inches long and 2.5 inches in diameter. Monkeys and other animals eat the seeds. The foliage of Pachira aquatic (L), flower (C), and fruit (R). Most of this area is well‐matured secondary growth. Huge trees towered over a very thick understory of small trees, palms, and shrubs. Some of the other plants we focused on included raffia palm, Raphia taedigera, that we also saw lots of on the boat ride here. This is one of about 20 species of palms in the genus Raphia (the others are native to tropical Madagascar and Africa) that are a source of raffia fibers, produced from the membrane on the underside of each individual frond leaf, used in twine, rope, baskets and textiles. The plants have very long, arching leaves that create dense shade that limit the growth of other plants. They occur in dense stands along the edges of the canals in Tortuguero National Park, as well as in other swampy areas of the country. The other very common and distinctive tree here is gavilán (Pentaclethra macroloba). This tall tree in the pea family (Fabaceae) has pinnate leaves that are twice compound, arranged in a spiral on the stems, with 15‐20 paired leaflets. Erect, arching racemes of up to 200 small white flowers each produce a single fruit. The hard, curved, brown pods split open to release the seeds at maturity. This is common in the wet Atlantic lowlands, and in many parts of Tortuguero where the other hardwood trees had been harvested in the past, leaving these less useful (for timber, at least) trees behind. The leaves (L) and seed pods of Pentaclethra macroloba (C); this tree and raffia palms are some of the most common trees in Tortuguero National Park (R). Our boat pilot skillfully navigated through the shallows and fallen trees while Gustavo pointed out plants and birds and insects and mammals and reptiles. The group in the small boat (L) plying the canals of Tortuguero (R). We got good views of sloths and caimans, iguanas, emerald basilisks and turtles.