Caribbean Slope Research Articles

Distribution and habitat use patterns of the endangered Central American clouded oncilla (Leopardus pardinoides oncilla) in Costa Rica.

Montane cloud forests are highly threatened ecosystems that are vulnerable to climate change. These complex habitats harbor many species that suffer the negative consequences of this global phenomenon, such as shifts in their distribution and habitat use. The Central American clouded oncilla (Leopardus pardinoides oncilla) is the smallest and most endangered wild cat in Mesoamerica and is primarily reported in cloud forests throughout its distribution. The species is poorly understood, with no studies conducted in Central America assessing its habitat preferences. To bridge this knowledge gap, we sampled two mountain ranges in Costa Rica with camera traps and conducted an occupancy analysis to understand the anthropogenic and environmental features that influence oncilla habitat use within them. Additionally, we conducted spatial predictions of habitat use across its northern and southern range in Costa Rica to identify priority conservation areas for the species. We found that Central American clouded oncilla habitat use is driven primarily by environmental factors. Our results showed that oncillas select habitats with denser tree cover at high elevations, closer to permanent water sources, which may provide them with high prey density and a favorable habitat structure for their survival. Spatial predictions identified two main regions as conservation priority areas where threat mitigation efforts and monitoring should be implemented: the Caribbean slope of the Talamanca mountains, and the Arenal-Monteverde forest complex. The occupancy modeling approach turned out to be very useful to assess the spatial associations of the species with the environment and mapping the conservation priority areas. Future research and mitigation actions should focus on potential threats that could negatively impact Central American clouded oncilla populations and habitat use, including the role of mesopredators and feral species.

Preliminary analysis of acoustic detection of the Red-throated Caracara in northern Costa Rica

The noisy Red-Throated Caracara (Ibycter americanus) is a species whose population has inexplicably declined across much of its range and is now rare in the Pacific and Caribbean slopes of Costa Rica. Advances in automatic acoustic detection have transformed bird ecology, allowing researchers to analyze bird populations using pattern matching algorithms, machine learning, and random forest models. Although these studies are limited in the country, it represents an area with great interdisciplinary potential for technological advances. This study focused on the use of Pattern Matching to detect the presence of the Red-Throated Caracara in northern Costa Rica using a large number of sound recordings and its validation with metrics such as Accuracy, Precision Negative predictive value, Sensitivity, Specificity and Unweighted average recall. The results showed a moderate performance of the model by obtaining accuracy and precision values of 0.71 compared to the values obtained in other investigations in which the reported model was used. Therefore, we suggest exploring new techniques and methods to improve the detection of the species, considering the particular acoustic structure, the repertoire of sounds of the species and similarities with vocalizations of other species. This similarity could indicate a supposed anti-predator defense behavior by “imitating” the sounds of other species with which it shares habitat. To optimize this acoustic detection, we recommend using complementary techniques such as noise filters that improve the quality and precision of the data.

Stable hydrogen isotope evidence of late-Holocene precipitation variability on the Caribbean slope of the Cordillera Central, Costa Rica

In Central America and the Caribbean, periods of increased aridity that correspond to the Terminal Classic Drought (TCD; 1200–850 cal yr BP) and the Little Ice Age (LIA; 500–100 cal yr BP) have been documented in many paleoclimate records. Compound-specific hydrogen (δDalkane) and carbon (δ13Calkane) isotopic compositions of n-alkanes in lake sediment can be used to interpret changes in paleoprecipitation and terrestrial paleovegetation, respectively. To assess the climate forcing mechanisms that drove the TCD and LIA, we established a multidecadal to centennial-scale late-Holocene reconstruction of precipitation variability and vegetation change at mid-elevation on the Caribbean slope of Costa Rica, developed from new δDalkane, δ13Calkane, and geochemical analyses and previous pollen and microscopic charcoal analyses from a sediment core from Laguna María Aguilar. Laguna María Aguilar is a freshwater lake located at 770 m elevation on the Caribbean slope of the Cordillera Central. During the TCD, δDalkane data for María Aguilar indicate relatively wet conditions compared to the mean δDalkane value for the entire record. Other proxy records for the TCD indicate that the Pacific slope of Costa Rica and sites above 3400 m near the continental divide experienced generally drier conditions than mid- and low-elevations on the Caribbean slope. We conclude that the TCD may have been driven by both Pacific and Atlantic climate-forcing mechanisms. During the LIA, the Laguna María Aguilar δDalkane record indicates an increase in hydroclimate variability, with some of the highest recorded δDalkane values (driest conditions) during the earliest portions of the LIA, but conditions were not persistently dry for the entirety of the LIA. Based on regional paleoclimate records overall, the LIA drought appears to be more clearly expressed on the Caribbean slope than on the Pacific slope of Costa Rica, indicating that the LIA was perhaps driven primarily by Atlantic Ocean conditions and climate dynamics.

Range expansion of white lipped foam-nest frog Leptodactylus fragilis on to the Caribbean slope of Costa Rica

Range expansion of white lipped foam-nest frog Leptodactylus fragilis on to the Caribbean slope of Costa Rica

Caracterização climática e análise dos mecanismos de modulação do declínio das chuvas na encosta caribenha da América Central durante setembro-outubro

[Introduction]: The Caribbean slope of Central America is located windward of the trade winds associated with the North Atlantic Subtropical High. The region exhibits rainfall bimodal annual patterns, with a relative minimum occurring in September and October. [Objective]: The study aims to characterize the observed decrease in rainfall during this two-month period. For each event, the variables associated with the onset day, minimum day, demise day, duration, intensity, and magnitude were estimated for the period of 1979-2010. [Methodology]: A set of 31 daily records from rain gauge stations was used. The months from July to November were examined in each station to identify the values of minimum, date of the minimum, onset, demise, duration, and intensity. The study explored the occurrence of any temporal or spatial trend in these characteristics of the events. Finally, different climatic indices and documentary sources were reviewed to identify the possible synoptic causes of the strongest decreases in rainfall. [Results]: The analysis revealed that the events began around September 3rd, with a minimum on September 23rd and an end on October 12th, with an approximate duration of 39 days. Events tend to occur earlier at stations located northwest of the isthmus. The driest events occurred under favorable conditions for the occurrence of winds with a southwest-west component over the region. [Conclusions]: Knowledge about these characteristics of precipitation helps in the activity planning of key socioeconomic sectors in Central America in case of adverse hydrometeorological events.

Eschweilera foetulenta and E. magnifica (Lecythidaceae), two new species from the rainforest of the Caribbean slopes of Panama

Eschweilera foetulenta and E. magnifica (Lecythidaceae), two new species from the rainforest of the Caribbean slopes of Panama

Spatial distribution of daily and monthly precipitation in the Caribbean side of Costa Rica

The spatial variations of trends of relevant monthly and daily precipitation, as the probability of wet or dry conditions is taken into considerations to see the amount of precipitation per station. The research examined six rainfall stations in the Caribbean range of Costa Rica in a period between 1989 to 2019. The research uses the rain data provided for a National Meteorological Institute (IMN) and the figures were made using ArcGIS this study aims to consider the amount of precipitation, the mean daily and monthly and total rainfall and probability of wetness. It was shown how on the Caribbean side some months have an opposite answer compared to the Pacific side during the La Niña event. For instance, certain months like March, April and October present some dryness. The research reflects that in the Caribbean slope of Costa Rica the warm phase behaves in the opposite way with respect to the warm phase on the Pacific slope. Costa Rica even though is a small country (51.179km²) is far from being uniform, and the results presented in this research reveal differences in the daily and monthly rain even in the Caribbean slope and increasing impact in monthly and daily circulations over the Atlantic through the Jet streams (CLLJ).

Two New Cauliflorous Species of Aristolochia subseries Anthocaulicae (Aristolochiaceae) from Southern Central America

Abstract— Two new cauliflorous species of Aristolochia subseries Anthocaulicae from southern Central America are described and illustrated. Aristolochia guanacastensis from northwestern Costa Rica resembles A. ruiziana, from which it is distinguished by having glabrous and narrower leaves, larger flowers without a syrinx, and shorter fruits. Aristolochia povedae from the Caribbean slope of Costa Rica and Panama is similar to A. cordiflora, but it is distinguished by its smaller, suborbicular and concave perianth limb with a shallower sinus, and slightly larger fruits. Comments about their distribution, habitat, phenology, conservation status, and distinction from related species are provided, and also a key to the species of Aristolochia subseries Anthocaulicae present in Central America. Evidence that supports the synonymization of A. cruenta under A. goudotii is presented.

A new species of brilliant green frog of the genus Tlalocohyla (Anura, Hylidae) hiding between two volcanoes of northern Costa Rica

A new species of hylid frog is described from Tapir Valley Nature Reserve, located on the Caribbean slope of Tenorio Volcano in Bijagua, Alajuela Province, Costa Rica. A molecular phylogenetic analysis supports its inclusion in the genus Tlalocohyla. Morphological, morphometric, larval, and acoustic characteristics further distinguish it from other species in the genus and support its uniqueness. The new species is closely related to T. picta and T. smithii, and is separated by at least 500 kilometers from the nearest known occurrence of a population of T. picta in southern Honduras. The new species is readily distinguished from all other Tlalocohyla by its brilliant green coloration marked with a pronounced, incomplete light dorsolateral stripe that is bordered above by a diffuse reddish-brown stripe. Its dorsum is marked with bold reddish brown spots and its ventral skin is fully transparent. This new Tlalocohyla is currently only known from the type locality, where it inhabits a lentic wetland system with an emergent herbaceous vegetation-dominated benthic zone, surrounded by tropical rainforest. A description of its bioacoustic repertoire and information on natural history, reproduction and habitat preference of this new species are provided.

Allometric Models to Estimate Carbon Content in Arecaceae Based on Seven Species of Neotropical Palms

We present allometric models for estimating total carbon content and above ground carbon (AGC) for the Arecaceae family, and for seven abundant neotropical palm species: the canopy speciesSocratea exorrhiza(n= 10) andIriartea deltoidea(n= 10), the sub-canopy palmEuterpe precatoria(n= 10), and the understory speciesAsterogyne martiana(n= 15),Prestoea decurrens(n= 10),Geonoma interrupta(n= 10), andChamaedorea tepejilote(n= 22). Understanding the allometry of functional groups such as palms is critical for improving carbon stocks estimates in tropical forests and determining how allometric differences affect species functional diversity. The research was carried out in the tropical rainforests of the Caribbean slope of Costa Rica. We harvested 87 palms of a wide range of sizes, and separated them into roots, stems, and leaves, measured their fresh and dry biomass, and calculated their carbon content, tissue density, and dry mass fraction (dmf). Our general palm model estimating total carbon content based on these seven species and 87 samples accounted for 92% of the variation across species. We generated a similar model to estimate AGC and explained 91% of the variation. We compared our AGC model with two models used to estimate palm carbon content:Goodman et al. (2013)’s andChave et al. (2014)’s models and found that all three converged on the estimation of AGC although our model was the most parsimonious because it achieved the same efficiency with only two variables, stem diameter and stem height. To improve the accuracy of allometric models we need to incorporate more species, a greater diversity of growth forms, a wider range of sizes, a larger sample size, and more diversity of habitats dominated by palms. Estimating carbon content using allometric approaches could benefit from more consistency in data collection across plant groups.

Dancing in the Rain: How Do Abiotic Conditions Influence Sexually Selected Behaviors in the White-Ruffed Manakin?

Tropical animals respond to rainfall in population-specific ways. In extremely wet regions, endotherms experience heavy rains as stressors with consequences for behavior and demography. Ultimately, such stressors can affect the relative strength of abiotic selection, reducing the scope for sexual selection, and other biotic sources of selection. We studied population-level differences in the response to rainfall of White-ruffed manakins (Corapipo altera) on the Caribbean slope of Costa Rica, a species having a lek mating system subject to strong sexual selection. Between 2008 and 2013, we studied reproductive behavior in a population inhabiting an extremely wet site; estimates of apparent survival were low, and the turnover of display courts and dominant males was high. Males also engaged in coordinated display, and sub-adult males practiced in the presence of adults. Over three breeding seasons (2017-2019), we studied a population of the same species at a site only 110 km away, but in a location receiving roughly half as much rain. We tested behavioral predictions of three alternative mechanisms-indirect abiotic effects, direct mortality effects, and direct behavioral effects-linking rainfall to sexual selection in these two populations. Data derived from over 4300 h of observations at 105 display sites revealed high interannual variation in nearly all response variables, including turnover of display sites, retention of alpha status, male display behavior, and time females spent assessing male display. Additionally, we detected spatial differences in drivers of display site turnover. Notably, age distribution of males was skewed toward older individuals at the drier location. Based on these findings, we infer that indirect abiotic effects on forest structure leading to display site transience and direct effects of mortality increasing turnover in the male population likely underlie links between rain and the spatial and temporal differences we documented. Our results are consistent with rain constituting an important source of abiotic selection for tropical endotherms and modulating the scope for sexual selection near the extremes of a species' hygric niche.

New species and records of Cloeodes Traver, 1938 (Ephemeroptera, Baetidae) from Costa Rica.

The nymph of Cloeodes dantasp. nov. is described from male and female nymphs collected from highland streams in the Caribbean Slope of the Costa Rica Central Volcanic Mountain Range. Adults are unknown. In addition, C. excogitatus and C. redactus are recorded for the first time in the country. Cloeodes dantasp. nov. can be differentiated from all described species by the predominantly brownish coloration on females and a similar coloration on males but with segments VII–IX light yellow and light brown, with no conspicuous marks or patterns; abundant scale-bases throughout most parts of the body; hindwings pads absent; the presence of three spines in the corners of the posterior margin of sternum III, and the posterior margin of tergum III with 28–30 spines on each side of the middle line (spine with a base width up to 0.5× spine length).

Bayesian estimates of the mean recharge elevations of water sources in the Central America region using stable water isotopes

Study regionCentral America Study focusKnowledge of the mean recharge elevation (MRE) of water resources is important where water resources are vulnerable. The purpose of this study was to develop and apply a Bayesian approach which incorporates isotopic uncertainties and evaporative effects on isotopic compositions to determine the MRE of 680 surface water sources from Central America. Differences were assessed between results from our approach and those from other isotope-based methods that do not account for these factors. New hydrological insights for the regionDifferent MRE patterns were identified for Pacific and Caribbean basins, which were characterized by distinct isotopic signatures: 1) the Pacific slope had recharge occurring at higher elevations relative to the source mean catchment elevation (MCE) and 2) the Caribbean slope had recharge largely occurring at elevations lower than the MCE. These relationships were quantified: MREP = 1.072 (MCE) + 45.65 (Pacific: r2 = 0.93, error = 144 m); MREC = 0.9493 (MCE) – 28.24 (Caribbean: r2 = 0.83, error = 190 m). The MRE, surface water site elevation (SWSE), and MRE-SWSE differences were generally greater on the Pacific slope, which hosts most of the region’s population. Bayesian MRE estimates were on average lower than MREs obtained using other methods and may better approximate the actual (recharge-weighed) MRE, suggesting that the inclusion of isotopic uncertainties, evaporative corrections, and recharge likelihoods all positively effect MRE estimations.

First record of Elga leptostyla Ris, 1911 (Odonata, Libellulidae) from Costa Rica

During research in the Tirimbina Biological Reserve, on the Caribbean slope of Costa Rica, we captured adult specimens and reared larvae of the dragonfly Elga leptostyla Ris, 1911, which belongs to the Libellulidae. This species was previously reported only from southern Panama to northern South America. Therefore, this is the first record of the species and genus from Costa Rica, increasing the number of Libellulidae species recorded in the country to 95. This species’ known distribution is northwards.

Costa Rica’s Water Paradox: Linking Rainforests and Droughts through the Water-Energy-Food-Environment Nexus in Guanacaste Province

Costa Rica is known as a verdant, tropical paradise with rich rainforests, abundant wildlife, striking mountains and volcanoes, and picturesque beaches. However, the perceived abundance of Costa Rica’s water resources is only true for part of the country. The same geography and climate that bring abundant precipitation to most of southern Costa Rica and its Caribbean coast also leave the northern Pacific province of Guanacaste with substantially less rainfall and even periods of severe drought. This case study focuses on Guanacaste province, which is a major tourist destination as well as one of the country’s most productive agricultural regions. Water from the lush Caribbean slopes of the Lake Arenal region is transported across the continental divide through extensive infrastructure projects. Passing through the semi-arid regions of Guanacaste, hydroelectric power generation, extensive irrigated agriculture, and tourism development use most of the water, supporting a rapidly growing regional economy but leaving increasingly less water for environmental flows. This case study introduces students to “nexus thinking” to explore the multiple and overlapping water, energy, and food (WEF) demands and ecological challenges present in Guanacaste province. Each sector and its interconnections with other sectors are examined in turn through introductory lectures, and enriched by WEF systems thinking activities and class discussions. At the conclusion of this case study curriculum, students will be able to identify and characterize points of intersection, i.e., the nexus, of WEF supply and demand, and trade-offs that exist between WEF resources and biodiversity conservation.

The complete mitochondrial genome of Sturisomatichthys panamense (Siluriformes: Loricariidae) analysed by next-generation sequencing and phylogeny of the catfish subfamily Loricariinae (Siluriformes: Loricariidae)

Sturisomatichthys panamense (Loricariidae, armored catfishes) is widespread throughout Central and South America from Pacific slope rivers of Panama to Caribbean slope rivers of Colombia. Due to the incredible body shape, it becomes one of the most popular pet fish in the world. However, little research has been done for this species, especially its genetic resource. In the present study, the complete mitochondrial DNA genome of S. panamense was first reported by next-generation sequencing method. The entire length of mitochondrial genome is 16,497 bp and the nucleotide composition was made up of 31.2% A, 28.3% C, 25.5% T, and 15.0% G, respectively, indicating an A + T (56.7%)-rich feature in the S. panamense complete mitogenome. The mitogenome includes 22 transfer RNA genes, 2 ribosomal RNA genes, 13 protein-coding genes and one control region. With the exception of 8 tRNA genes and NADH6, mitochondrial genes are encoded on the heavy strand, which was in line with other vertebrates. Phylogenetic trees centred on the Loricariinae were reconstructed using another 72 reported cytochrome c oxidase I (cox1) gene sequences. They indicated monophyly of the Loricariinae and presented a basal split within the Loricariinae resulting in two major tribes, the Loricariini and the Harttiini. Sturisomatichthys panamense was placed with Sturisoma panamense and formed a sister group to Sturisomatichthys citurensis in the phylogenetic trees.

A Taxonomic Revision of Sturisomatichthys Isbrücker and Nijssen, 1979 (Loricariidae: Loricariinae), with Descriptions of Three New Species

A taxonomic revision of Sturisomatichthys is presented. A total of 383 specimens including both type and non-type specimens of all valid species were examined. Sturisomatichthys was found to encompass ten valid species: Sturisomatichthys aureus, S. caquetae, S. citurensis, S. dariensis, S. festivus, S. frenatus, S. kneri, S. leightoni, S. panamensis, and S. tamanae. In addition, three new species are described: Sturisomatichthys reinae, new species, from the Baudo River, in northwestern Colombia, belonging to the Caribbean slope of the continent; Sturisomatichthys guaitipan, new species, from the upper and middle Magdalena River basin, Colombia; and Sturisomatichthys varii, new species, from the San Juan River basin in western Colombia, on the Pacific slope. Sturisomatichthys caquetae, from the Morelia River, upper Amazon, is transferred back from Sturisoma, and S. leightoni was found to be distributed, besides the Magdalena-Cauca basin, in the Orinoco basin; thus, Sturisomatichthys is shown to be distributed in both trans- and cis-Andean drainages. A neotype is designated for S. aureus from the lower Magdalena basin. New records of localities in the northwestern region of South America, as well as the redescription and taxonomic comments on all valid species, are provided. Maps with the species distributions and a key for identification of the species are provided.

Otoba vespertilio (Myristicaceae), una especie nueva de Mesoamérica

Otoba vespertilio, a new endemic tree species from the Caribbean slope of Costa Rica and Panama, is described and illustrated. This species is similar to O. cyclobasis, but differs in having leaf blades with 6–8 secondary veins per side (vs. 14–17) and staminate flowers with the pedicel 2–3.6 mm long (vs. 4–5 mm) and without an extrastaminal disc surrounding the base of the staminal column (vs. extrastaminal disc present). Data on its distribution and habitat, phenology, and taxonomy are included, as are photographs of the living plant and a key to identify the four species of the genus in Mesoamerica.

Drivers of tropical rainforest composition and alpha diversity patterns over a 2,520 m altitudinal gradient.

AimWe sought to determine the relationship of forest composition and alpha diversity (the species diversity of a local assemblage) to altitude, soil, and spatial factors over a 440–2,950 m a.s.l gradient.LocationAltitudinal gradient on the Caribbean slope of the Talamanca Cordillera, Costa Rica.TaxonAngiosperm and gymnosperm trees, palms, and tree ferns.MethodsWe measured and identified all stems ≥10 cm dbh in 32 0.25‐ha undisturbed rain forest plots over the gradient. We determined compositional patterns using Non‐Metric Multidimensional Scaling (NMS) ordination, and used linear regressions to explore the relationship between four alpha diversity metrics and altitude. With variation partitioning (VARPART), we determined the compositional variation explained by altitude, soil, and spatial variables quantified using Principle Components of Neighbor matrices.ResultsWe identified 425 species. NMS axis 1 separated a lowland zone (440–1,120 m asl) from a transitional one dominated by holarctic Oreomunnea mexicana (1,400–1,600 m asl) and Quercus‐dominated forests at altitudes >2,100 m asl. The lowland zone was separated into two clusters of plots on NMS axis 2, the first in the 430–620 m asl range and the second at 1,000–1,120 masl. Regressions showed that all alpha diversity metrics were strongly negatively related to altitude (R 2 > 0.78). Overall, adjusted R 2 from VARPART was 0.43, with 0.30, 0.21, and 0.17 for altitude, soil, and space respectively. The respective adjusted R 2 of individual matrices, on controlling for the other two, was 0.06, 0.05 and 0.09 (p < 0.001).Main conclusionsThere are two well‐defined forest compositional zones on this gradient—lowlands 430–1,120 m asl and montane forests >2,150 m asl—with a transitional zone at 1,400–1,600 m asl, where lowland tropical and montane holarctic species are found together. Montane forests are very distinct in their composition and low alpha diversity. Vegetation and soil respond to altitude, and therefore temperature, as an integrated system, a model that goes beyond niche assembly as shown by the significant effect of space in the VARPART.

Relative humidity, temperature, substrate type, and height of terrestrial lichens in a tropical paramo

Lichens are traditionally divided into types such as "crustose", "foliose" and "fruticose", with different shapes and heights. Substrate, temperature and water are thought to affect lichen height, but there are few studies regarding tropical paramo lichens. Along 2015 I measured those variables in the terricolous lichens of the Cerro Buena Vista, paramo (Costa Rica, 9°33' N &amp; 83°45' W). The measurements were taken inside the lichens and in the substrate under them, in 61 randomly located quadrats (50 x 50 cm). Lichens grew taller on (1) warmer ground, (2) wetter ground, (3) the moister Caribbean slope, and (4) the season with heavier rainfall, as expected. Apparently, atmospheric factors are more important than substrate in the determination of temperature, relative humidity and growth of lichens. Physiologically available water seems to be the main determinant of lichen vertical growth in the Buena Vista paramo.