Pacific Slope Of Costa Rica Research Articles

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.

End-Point Predictors of Water Quality in Tropical Rivers

End-point evaluation of stream health is essential for the quantification of water quality. To this end, many Multi-Metric Indices (MMIs) have been developed to quantify water quality. The most extensive work has occurred in North America and Europe, while other areas of the world are in development. In this study, we compared the use of relevant physical, chemical and biological parameters in MMIs to various other stream health indicators to assess water quality throughout a three-river corridor along the north central Pacific slope of Costa Rica. Analysis of the data suggested MMIs were the best indicators of water quality and, more specifically, insect MMIs were the most predicative. MMIs were also best at pinpointing anthropomorphic impact throughout the corridor. Further, less complex insect MMIs such as compilations of family diversity using Ephemeroptera, Plecoptera and Trichoptera (EPT) orders were equally as predictive as the more complex models. With a need to better understand and use citizen monitors to predict water quality in these tropical environments, less complex insect MMIs show promise as a solution.

Estimates of growth and longevity of six species of freshwater shrimps (Macrobrachium spp.) (Decapoda: Caridea: Palaemonidae) from Costa Rica

AbstractInformation about growth is of particular relevance for stock assessment and management as well as for evaluating the aquaculture potential of any decapod species, but this information is lacking for the Central American species of MacrobrachiumSpence Bate, 1868. We collected specimens of six species of Macrobrachium monthly (February 2006 to August 2008) along the Pacific slope of Costa Rica. The collected individuals were sexed and weighted, and total length (TL) and carapace length (CL) were measured. The von Bertalanffy growth model was fitted to the data by applying the maximum likelihood method. The species analyzed reaching theoretically the largest sizes were M. americanum (Spence Bate, 1868), M. tenellum (Smith, 1871), and M. panamenseRathbun, 1912. With few exceptions, maximum sizes of all species were generally higher than those published in previous reports, suggesting that environmental conditions are favorable and anthropogenic impacts may be less severe in Costa Rica than in other countries. Only M. americanum exceeded the asymptotic total length estimates of other species, corroborating that this species is considered as one of the largest congeners worldwide. Estimated maximum age ranged from 3.9 (M. occidentaleHolthuis, 1950) to 11.5 yrs (M. tenellum). All six Macrobrachium species showed a positive allometric growth type. The model describing the length-weight relationship was statistically significant (P < 0.05) for all species. Although the maximum likelihood method has been applied so far mainly to compare different growth models, here we used this method to generate the first growth estimates for the six species from Costa Rica, and future studies might use this method to compare growth patterns among different species.

Long‐term monitoring of Yellow‐naped Amazons ( Amazona auropalliata ) in Costa Rica: breeding biology, duetting, and the negative impact of poaching

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A new species of stingless bee (Meliponini) from Costa Rica

A new species of stingless bee, Trigona (Trigonisca) discolor , is described from the Pacific slope of Costa Rica. A brief discussion on its systematic position in also given.

Coleoptera: Scarabaeidae Observations on the behavior of a tropical rain forest dung beetle, Megathoposoma candezei (Harold)

Megathoposoma candezei dung beetles at the southerft base of Cerro Nara, 17 km north of the mouth of the Savegre River, on the southern Pacific slope of Costa Rica, are diurnal, in contrast with the Mexican populations; there are from 15 to 19 beetles per 50,000 m2 at 760-780 m elevation; below 600 m populations diminish considerably. Among the more obvious protective mechanisms are cryptic coloration and thanatosis which may last over two hours. These beetles avidly seek human excrement which they make into almost perfect balls, coat with mud, and buey in superficial chambers where they spend about 60 hours consuming them. Copulation takes place over the food pile, which represents the most primitive leve1 of sexual behavior so far known in Scarabaeini; rolling of the dung balls by couples was not observed.

Licaria leonis (Lauraceae), una nueva especie del Pacífico costarricense, y algunas notas sobre Licaria multinervis H. Kurz

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><span> Una nueva especie de Licaria Aublet (Lauraceae) de las tierras medias de la vertiente pacífica de Costa Rica se describe y se ilustra en este artículo. Esta nueva especie es comparada con L. multinervis y se menciona que una especie no descrita de Endlicheria Nees puede ser solamente </span>una forma inmadura de L. multinervis. </p></div></div></div>

Patterns of genetic and morphological divergence reveal a species complex in the Plain Wren (Cantorchilus modestus)

ABSTRACT We used morphometrics, plumage color, and mitochondrial DNA to reconstruct the phylogeography of the Plain Wren (Cantorchilus modestus), an abundant bird species of low to middle elevations throughout Central America. Sampling the full geographic range of C. modestus, we uncovered significant phenotypic structure in size, shape, and plumage color that mirrored deep genetic divergences in mitochondrial DNA. This structure was mostly concordant with the 3 most broadly recognized subspecies of Plain Wren (C. m. modestus, C .m. zeledoni, and C. m. elutus), but a potentially undescribed taxon exists in the highlands of Central Belize. We also found evidence of a cryptic phylogeographic break on the Pacific Slope of Costa Rica, between the southernmost populations and the widespread northern populations. This latter discovery likely represents a significant expansion of the known range of the traditionally Panamanian subspecies C. m. elutus, corresponding to a transition between major ecoregions. Topol...

Population density and habitat preferences of the Black-cheeked Ant-tanagerHabia atrimaxillaris

SummaryThe lowland forest on the southern Pacific slope of Costa Rica has an extremely diverse avifauna, including the Black-cheeked Ant-tanagerHabia atrimaxillaris. The only known remaining populations of this highly range-restricted species occur in the areas of Piedras Blancas and Corcovado National Park. It is assumed that the population is decreasing due to habitat loss and fragmentation. We assessed the species’ population density in a part of the Piedras Blancas National Park using distance sampling (in February–April 2009 and November 2010–January 2011) and territory mapping (November 2010–January 2011). We also examined habitat preferences based on vegetation structure at point count locations. Black-cheeked Ant-tanagers were exclusively found in old-growth forest. The species’ likelihood of occurrence at census points increased with forest cover (within a radius of 200 m around census points), canopy closure, and density of trees (with diameter at breast height >10 cm). Average population density estimated by distance sampling was 24–27 individuals per km², which is in accordance with the population size estimated by territory mapping (17–25 birds per km²). Based on these estimates, an overall population size of 12,432–20,720 birds is predicted for the remaining 592 km² lowland forest area of the Golfo Dulce region. The Black-cheeked Ant-tanager was only recorded in old-growth forest, but not in gallery forests embedded in a human-dominated landscape matrix. Since the species appears to avoid forest edges, further forest degradation and fragmentation will have a strong negative impact and should be rapidly reduced by adequate conservation measures.

Species diversity and distribution of freshwater crabs (Decapoda: Pseudothelphusidae) inhabiting the basin of the Rio Grande de Terraba, Pacific slope of Costa Rica

During the last decades, knowledge on biodiversity of freshwater decapods has increased considerably; however, information about ecology of these crustaceans is scarce. Currently, the freshwater decapod fauna of Costa Rica is comprised by representatives of three families (Caridea: Palaemonidae and Atyidae; Brachyura: Pseudothelphusidae). The present study aims to describe the species diversity and distribution of freshwater crabs inhabiting the basin of the Rio Grande de Terraba, Pacific slope of Costa Rica, where the Instituto Costarricense de Electricidad (ICE) plans to implement one of the largest damming projects in the region. Samples were collected in 39 locations at an altitude ranging from 20 to 1,225 m. Sampling was carried out during several months in 2007, 2009 and 2010. We collected a total of 661 crabs, comprising eight species of Pseudothelphusidae of three genera, representing 53% of the 15 pseudothelphusid crab species currently recorded from Costa Rica. The most common species was Ptychophallus paraxanthusi followed by P. tristani . Freshwater crabs were more frequently encountered in the middle-low region of the basin (between 311 and 600 m) and less frequently in the medium-high basin (between 601 and 1,225 m). Ptychophallus paraxanthusi showed the widest distribution and was collected in altitudes ranging from 20 to 700 m. The Rio Grande de Terraba region can be considered as a relatively small, but highly diverse system. Therefore, any alteration of the basin of Rio Grande de Terraba, and especially the possible construction of a hydroelectric power plant, needs to be carefully analyzed to mitigate the damaging effects of this project on the freshwater crabs. More ecological information about freshwater crabs from Costa Rica and the Central American region are needed to reach a first reasonable overview on the ecological role of these decapods in freshwater systems.

A new species of Roeboides (Teleostei: Characidae) from Costa Rica and Panama, with a key to the middle American species of the genus

A new species of Roeboides is described from the Pacific slope of Costa Rica and Panama. Roeboides bussingi differs from all other Central American Roeboides and all members of the R. guatemalensis species group by the following combination of characters: presence of 18-22 scales above the lateral line (vs. 12-16 in R. dientito); 15-22 scales below the lateral line (vs. 10-14 in R. dientito, and 20-24 in R. loftini); an inconspicuous, sometimes absent, crescent-shaped humeral spot (vs. a large round, conspicuous humeral spot in R. carti, R. dayi, R. dientonito, R. ilseae, R. loftini,and R. occidentalis); a small wedge-shaped spot that does not reach the lateral line (vs. a large spot crossing the lateral line in R. guatemalensis); a teardrop shaped caudal spot (vs. caudal spot triangle shaped in R. bouchellei); and a dark band at the distal tip of the anal fin (vs. dark band absent in R. bouchellei). A key to all Middle American species of Roeboides is also presented

Two new species of the bee genus Peponapis, with a key to the North and Central American species (Hymenoptera: Apidae: Eucerini)

Two new species of squash bees, Peponapis pacifica Ayala and Griswold sp. n. and P. parkeri Griswold and Ayala sp. n., are described and illustrated. Peponapis pacifica is oligolectic on flowers of Schizocarpum longisepalum (Cucurbitaceae) endemic to Mexico, where it is found in the tropical dry forest along the Pacific Coast, between Sonora and Chiapas and in the Balsas River basin; and P. parkeri is known only from the Pacific slope of Costa Rica. A key for the North and Central American species of Peponapis is provided.

Phylogeography of the Pygmy Rain Frog (Pristimantis ridens) across the lowland wet forests of isthmian Central America

We used a phylogeographic approach to elucidate the evolutionary history of a lineage of frogs, known as Pristimantis (formerly Eleutherodactylus) ridens (Anura: Brachycephalidae), restricted to the wet forests occurring along the Caribbean versant of isthmian Central America as well as the disjunct wet forest on the Pacific slope of Costa Rica. We placed our phylogeographic study of P. ridens within a larger molecular phylogenetic analysis of Central American Pristimantis. All phylogenetic inferences were based on a 1455 base pair fragment of mitochondrial DNA, containing the complete ND2 gene and five flanking tRNA genes. Our reconstruction of the intraspecific phylogeny of P. ridens yielded a basal trichotomy dating to an estimated 12+ million years ago (Ma), consisting of central Panama, western Panama, and Costa Rica plus Honduras. Thus, the presence of P. ridens appears to predate the completion of the Isthmus 3.1Ma. Using a parametric bootstrap (SOWH) test, we evaluated four a priori zoogeographic hypotheses for the origin and spread of P. ridens. This analysis suggested that the P. ridens populations on the Caribbean versant of Costa Rica were established by Pacific versant ancestors only recently, in contrast to the very old lineages found in Panama. Our results support a model of Miocene colonization, long-term geographic stasis, followed by rapid dispersal across the Caribbean lowlands during the Pliocene or Pleistocene.

The role of tropical dry forest as a long‐term barrier to dispersal: a comparative phylogeographical analysis of dry forest tolerant and intolerant frogs

We used a comparative phylogeographical approach to investigate the origins of the disjunct wet forest biota of the Golfo Dulce region along the Pacific slope of Costa Rica. This region is isolated by Pacific dry forests north and south and isolated from Caribbean wet forests by mountains. We studied three sympatric lowland frog species in the Craugastor fitzingeri species group that prefer wet forest but differ in their response to dry habitats. In dry forest, C. fitzingeri can survive along streams while C. crassidigitus and C. talamancae are entirely absent. We collected samples from across the ranges of all three species, and obtained mitochondrial DNA sequence data from the COI and cytochrome b genes. We observed significant phylogeographical structure in C. crassidigitus and C. talamancae, but much less in C. fitzingeri, demonstrating that mountain barriers and dry forest habitat have reduced mitochondrial gene flow in the strictly wet-forest species. Additionally, we discovered that the Golfo Dulce and Central Panama populations of C. crassidigitus appear to have diverged in the Pliocene or earlier, suggesting that the dry forest separating these populations is old. Our phylogenetic analysis of 12 of approximately 16 species of the C. fitzingeri species group suggests that the three lowland species are each other's closest relatives. Because of this shared phylogenetic history, we attribute the striking differences in phylogeographical structure to the different ecologies of the frogs. In summary, we find that what appear to be minor differences in the natural history of these three closely related species may profoundly impact the potential for dispersal, range size, and cladogenesis.

Beetle (Coleoptera) and spider (Araneae) diversity in a mosaic of farmland, edge, and tropical forest habitats in western Costa Rica1

A central focus in applied entomology is the role that habitat diversity plays in the creation and maintenance of arthropod diversity. Researchers are increasingly exploring the possibility that degraded landscapes such as mixed-used agricultural areas and rainforest fragments might be used to supplement conservation strategies aimed at increasing arthropod biodiversity. Here we present the results of a comparative biodiversity field study in the Puriscal region on the Pacific slope of Costa Rica in a rural community characterized by a mixture of secondary forest and farmland. The study compares beetle and spider diversity among farmland, nearby tropical forest fragments, and weedy “edge” habitats. Diversity of families of Coleoptera and Araneae pitfall catches were compared in each of these three habitats, and quantitative similarity indices across habitats were calculated for the collected specimens. Diversity among the three habitats was similar for beetles, but spiders were more diverse in forest frag...

Seasonal variation in the stable isotopic composition of precipitation in the tropical montane forests of Monteverde, Costa Rica

Climate and land use change may diminish orographic clouds over tropical montane forests, stressing biota and water resources during dry seasons. From 2003 to 2005 we measured the stable isotopic composition of precipitation and throughfall in Monteverde, Costa Rica, to distinguish convective, wet season rainfall associated with the Intertropical Convergence Zone (ITCZ) from dry season, orographic rain produced by northeasterly trade winds. While event‐to‐event fluctuations of δ18O and δ2H are high, monthly samples reveal a seasonal signal that may be used to trace water through the hydrologic cycle. Deuterium excess indicates that water evaporated from land is an important flux to the region during the transitional and dry seasons when winds from the Caribbean slope dominate. Following the shift to convective rainfall at the start of the wet season, when the western equatorial winds influence the Pacific slope of Costa Rica, d excess values become depressed. Yet as the wet season progresses, d excess begins to climb. These data suggest that several months of rain are needed following an acute dry season on the northern Pacific slope before a terrestrial evaporative signal is detected in wet season precipitation. The evaporative flux may result from a wet season expansion of surface water bodies and flooding of seasonal wetlands.

The coincidence of daily rainfall events in Liberia, Costa Rica and tropical cyclones in the Caribbean basin

The occurrence of tropical cyclones in the Caribbean and North Atlantic basins has been previously noted to have a significant effect both upon individual hydro-climatological events as well as on the quantity of annual precipitation experienced along the Pacific flank of Central America. A methodology for examining the so-called ‘indirect effects’ of tropical cyclones (i.e. those effects resulting from a tropical cyclone at a considerable distance from the area of interest) on a daily rainfall record is established, which uses a variant of contingency table analysis. The method is tested using a single station on the Pacific slope of Costa Rica. Employing daily precipitation records from Liberia, north-western Costa Rica (1964–1995), and historic storm tracks of tropical cyclones in the North Atlantic, it is determined that precipitation falling in coincidence with the passage of tropical depressions, tropical storms, and hurricanes accounts for approximately 15% of average annual precipitation. The greatest effects are associated with storms passing within 1300 km of the precipitation station, and are most apparent in the increased frequency of daily rainfall totals in the range of 40–60 mm, rather than in the largest daily totals. The complexity and nonstationarity of factors affecting precipitation in this region are reflected in the decline in the number of tropical cyclones and their significance to annual precipitation totals after 1980, simultaneous to an increase in annual precipitation totals. The methodology employed in this study is shown to be a useful tool in illuminating the indirect effects of tropical cyclones in the region, with the potential for application in other areas. Copyright © 2005 Royal Meteorological Society.

Differential host use in two highly specialized ant-plant associations: evidence from stable isotopes.

Carbon and nitrogen stable isotopes were used to examine variation in ant use of plant resources in the Cecropia obtusifolia / Azteca spp. association in Costa Rica. Tissue of ants, host plants and symbiotic pseudococcids were collected along three elevation transects on the Pacific slope of Costa Rica's Cordillera Central, and were analyzed for carbon and nitrogen isotopic composition. Worker carbon and nitrogen signatures were found to vary with elevation and ant colony size, and between Azteca species groups. Ants in the A. constructor species group appear to be opportunistic foragers at low elevations, but rely more heavily on their host plants at high elevations, whereas ants in the A. alfari species group consume a more consistent diet across their distribution. Further, isotope values indicate that both ant species groups acquire more nitrogen from higher trophic levels at low elevation and when ant colonies are small. Provisioning by the host is a substantial ecological cost to the interaction, and it may vary, even in a highly specialized association. Nonetheless, not all specialized interactions are equivalent; where interaction with one ant species group appears conditional upon the environment, the other is not. Differential host use within the Cecropia-Azteca association suggests that the ecological and evolutionary benefits and costs of association may vary among species pairs.

New species of dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) from Costa Rica and Panama

The following new species of dung beetles (Coleoptera: Scarabaeidae) from Costa Rica and Panama are described: Copris tridentatus sp. nov., Onthophagus notiodes sp. nov., Onthophagus xiphias sp. nov. and Trichillum arcus sp. nov. Pedaridium bradyporum (Boucomont) is reported from the Pacific slope of Costa Rica for the first time. Drawings of the dorsal habitus of all species are provided.

Plants feed ants: food bodies of myrmecophytic Piper and their significance for the interaction with Pheidole bicornis ants.

Several species of Piper (Piperaceae) live in symbiosis with Pheidole bicornis (Formicidae-Myrmicinae) on the southern Pacific slope of Costa Rica. These plants produce small single-celled food bodies (FBs) in leaf domatia, formed by the petiole bases and roofing leaf sheaths. In the present study the dependency of ants on FBs of Piper fimbriulatum as a food source was analysed by comparing the natural abundance of 13C and 15N in ants and FBs. Both δ13C and δ15N values were very similar between FBs and Pheidole bicornis ants but differed substantially between the plant and other ant species. Therefore we suggest that FBs are a main food source for Pheidole bicornis ants. To strengthen this suggestion, the chemical composition of FBs of four myrmecophytic Piper species was analysed, with special emphasis on the nutritional requirements of inhabiting Pheidole bicornis ants. Standard chemical methods were modified and combined to a novel analysis scheme by which all major FB constituents could be quantified from minute [3-10mg dry mass (DM)] quantities. Piper FBs mainly consisted of lipids (41-48% of DM) and proteins (17-24% of DM). Soluble carbohydrates and amino acids proved to be quantitatively unimportant. N was predominantly stored as soluble protein and, thus, was easily available to the ants. FBs proved to be a high-energy food source (up to 23kJ g-1 DM), with a chemical composition that meets well the nutritional needs of the inhabiting ants.