Pacific Costa Rica Research Articles

Pre-Columbian agriculture, fire, and Spanish contact: A 4200-year record from Laguna Los Mangos, Costa Rica

We present a lake-sediment record of pre-Columbian agriculture and fire history from the lowlands of southern Pacific Costa Rica that captures the arrival of maize agriculture at ca. 3360 cal yr BP in the Diquís subregion of the Gran Chiriquí archeological region. Our 4200-year record from Laguna Los Mangos begins 1000 to 2000 years earlier than other lake records from the region and provides the first microfossil and geochemical evidence of vegetation and fire prior to the establishment of maize agriculture. This early portion of the record shows evidence of fire events associated with land clearance or field preparation and maintenance for subsistence activities. Alternatively, these were wildfires ignited unintentionally by people or naturally by lightning or volcanism. Evidence of early maize by ca. 3200 cal yr BP was found at Laguna Zoncho in the southeastern section of the Diquís subregion. Our discovery of early maize agriculture at ca. 3360 cal yr BP in the Laguna Los Mangos watershed in the northwestern portion of the Diquís subregion indicates a rapid adoption of maize agriculture in the region after initial introduction. Pre-Columbian agriculture and fire activity at Los Mangos is nearly continual until historic times, but with a decline after ca. 1170 cal yr BP, coincident with the early Terminal Classic Drought (TCD). We infer a pronounced drying of the lowland environment at Laguna Los Mangos based on a depositional hiatus in the record at ca. 950 during late TCD. Agricultural proxies indicate reduced watershed activity during the ‘Little Ice Age’ following Spanish contact in southern Central America until the 20th century.

The sound of a blood meal: Acoustic ecology of frog‐biting midges (Corethrella) in lowland Pacific Costa Rica

AbstractAnimal communication systems are often exploited by eavesdropping antagonists, especially predators and ectoparasites. Female frog‐biting midges (Diptera: Corethrellidae) are known to use male anuran advertisement calls to locate their blood hosts, frogs. Here, we use acoustic midge traps broadcasting synthetic and recorded calls to identify those frog call parameters that affect midge attraction. At our study site in Pacific lowland Costa Rica, we found that overall midge attraction was influenced by both spectral and temporal acoustic parameters. Low dominant frequencies (below 1 kHz) and short pulse durations (between 125 and 500 ms) attracted the highest numbers of midges in tests with synthetic sinusoidal pure tones. These preferences partially explained the relative attractiveness of the advertisement calls of ten local frog species. The advertisement calls of the common and widespread Giant Bullfrog, Leptodactylus savagei (Anura: Leptodactylidae), attracted by far the largest number of midges, suggesting that this frog species might be a key resource for frog‐biting midges in Costa Rica. Although we found that calls of different frog species attracted different midge species/morphospecies in statistically different proportions, acoustic niche differentiation among midge species appeared to be moderate, suggesting either a limited degree of host specialization or the use of additional short‐range, that is, chemical, host recognition cues.

Brucella sequence Type 27 isolated from Dwarf Sperm Whale (Kogia sima) stranded in the Costa Rican Pacific Coast

Brucella organisms are Gram-negative, intracellular facultative extracellular bacteria that infect a variety of animals. On March 2018, a pregnant dwarf sperm whale (Kogia sima), stranded and aborted on Herradura beach at the Pacific coast of Costa Rica. K. sima is a criptic species; very little is known of its biology and worldwide distribution, however it is still hunted in Asia. Brucella sp. was recovered from multiple tissues of the female and the calf, and examined by biochemical tests, MLVA-16, brucellader and HRM real time. The isolates were used for whole genome sequencing and the reads were aligned to Brucella abortus 9–941 as the reference, alltogether with other Brucella species. A total of 27 365 variable sites were extracted and a phylogenetic reconstruction by maximum likelihood was produced. The phylogenetic tree revealed that the K. sima isolates are related to Brucella sp. F5/99, a singular strain recovered on 1992 from a bottlenose dolphin captive in California, classified as sequence type (ST) 27 by multi-locus sequence type. This ST27 was described in Brucella isolates with zoonotic capacity and therefore transmission to humans from Peru and New Zealand. This is the first report of Brucella ST27 recovered from a host of the Eastern Tropical Pacific and of Brucella infection in a dwarf sperm whale. Our results shows that the range of marine mammals infected by Brucella sp. is wider than our current knowledge, and that biosafety measures should be increased when handling the stranded mammals, as the zoonotic transmission is of major risk.

Stable carbon and nitrogen isotope ratios of surface food residues in pre-Columbian ceramics from the southern Pacific of Costa Rica as evidence of prehistoric human diets

Introduction: to understand and interpret the consumption of plants and animals by humans in the past requires the investigation of different lines of evidence. Identifiable macroscopic remains of plants and animals, for example seeds and bones, are frequently found at archaeological sites and provide key data on food resources. Their analysis is complemented by the study of pollen grains or phytoliths of cultivated plants within archaeological horizons or in sediment cores recovered from lakes and wetlands near archaeological sites. Another important source of information on human diets in the past consists of food residues preserved in or on artefacts excavated from archaeological sites. Objective: to examine food residues in archaeological pottery from coastal and interior sites in the southern Pacific region of Costa Rica. Methods: we focus on isotopic analysis of carbonized food residues preserved on the inner surfaces of ceramic pots, plates, and other ceramic pieces from archaeological excavations in the intermediate zone (elevations 500-1500m) and coastal zone of the southern Pacific region of Costa Rica. Isotopic analysis of surface food residues on pottery relies on the fact that stable isotopes of carbon (12C and 13C) and nitrogen (14N and 15N) in foods differ based on the photosynthetic pathway of plants and on trophic level. Results: in our analysis of material from twelve sites we found evidence of diets with high amounts of C4 plants (likely maize), legumes, herbivores, and mixtures, but we did not find robust evidence of food residues with isotopic signatures characteristic of reef animals and mollusks, even though some sites are shell mounds. Conclusion: our research represents one of the first studies of surface food residues from Costa Rican pottery, and indicates the potential for studies of this type to strengthen understanding of indigenous subsistence patterns through time and across Costa Rican archaeological regions.

Influencia de la vigilancia en una zona rocosa dentro de un área marina protegida, Pacífico Central de Costa Rica

We present the results of conservation assessment of a rocky shore in the Central Pacific of Costa Rica (Playa Hermosa-Punta Mala National Wildlife Refuge) using the biological indicators proposed by the national environmental ministry. This study aims to analyze the influence of surveillance, between two sites, over the rocky shore habitat. The sampling was carried out during both the dry and rainy seasons in 2015. Our data shows that Nerita scabricosta -harvested in small-scale fisheries- presents a high number of colonies formed by few individuals. Moreover, the abundance varied between seasons, probably due to a storm surge. Macroalgae differed slightly among sites, where turf had higher percentage coverage in low surveillance areas, while brown algae had higher coverage in high surveillance areas. Mechanical damage (abrasion due to rocks overturning) associated with tourism and harvesting could be influencing the low surveillance area, explaining these differences. Macroalgae presented a seasonal change, probably related to the storm surge. The density of the Tetraclita stalactifera did not exhibit variations. The surveillance level and enforcement influenced some bioindicators of the rocky shore, and therefore could be used to assess the extractive pressure.

Bibliometry of marine science and limnology publications (1979-2015) by the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR), Universidad de Costa Rica

Bibliometrics play a significant role in evaluating the scientific production of journals and research units such as universities and research centers. The present study aimed to analyze the scientific production of CIMAR (Center for Research in Marine Science and Limnology) from its foundation in 1979 to 2015. We analyzed exclusively articles published in journals and selected those with at least one author affiliated to CIMAR. For the analysis, each article was classified according to the geographical study area, the topic of the investigation, ecosystem, and taxonomic group. We analyzed the following variables: year of publication, language, journal name, and authors. In this study, we analyzed the Bradford distribution, citations, the impact factor, and the quartiles of the journals where papers were published. During the study period, CIMAR produced a total of 791 publications: 624 articles, 90 book chapters or books, 48 booklets, and 34 special issues of the journal Revista de Biología Tropical (RBT). The number of publications showed an increasing trend during the study period, and most articles were written in English (58.3 %) and Spanish (41.7 %). A total of 128 journals were selected to publish CIMAR’s contributions. According to the Bradford method, the journal RBT is in Zone I (major productivity or concentration), with 49.8 % of the total scientific production. In relation to authorship, 22 authors with 12 articles or more are registered, and 80 % of the articles have been published by authors with a low (42 authors) and medium productivity level (44 authors). CIMAR published 81.6 % regarding marine topics and 18.4 % about limnology. Most of the articles (51.9 %) dealt with the Pacific of Costa Rica, 13.5 % with the Caribbean and 34.7 % referred to other study locations. The publications of CIMAR were mainly about ecology (33.3 %), taxonomy (24.5 %) and oceanography/meteorology (12.7 %). CIMAR has a highly trained and specialized staff that has gained experience and is contributing to the implementation and evaluation of Costa Rica’s science, technology and innovation policies through both interdisciplinary research and the development of institutional as well as professional capacities in a framework of dialogue and public-private agreements.

Estudios de zooplancton marino en Costa Rica: una revisión y perspectivas a futuro

This review summarizes marine zooplankton research performed in the Costa Rican Pacific and Caribbean coasts and at Isla del Coco National Park. Composition, abundance, biomass, distribution and some ecological features of the zooplankton for each system is discussed. Pacific coastal zooplankton composition has been described in Bahía Salinas and Bahía Culebra. The local oceanography of these bays is heavily influenced by the Papagayo wind jet, which produces seasonal coastal upwelling and most likely drives the seasonal changes in zooplankton abundance and biomass. Copepods and ostracods were the dominant taxonomic groups throughout the year with a strong seasonality, furthermore 53 hydromedusae species has been found, where Liriope tetraphylla (Chamisso & Eysenhardt, 1821), Solmundella bitentaculata (Quoy & Gaimard, 1833) and Aglaura hemistoma (Péron & Lesueur, 1810), were the most abundant species. Zooplankton herbivory rates at Gulf of Nicoya estuary was estimated over 50 % removal of primary production. This is a typical value for tropical productive environments. Copepods numerically dominated zooplankton community from the Gulf of Nicoya. Other dominant taxa includes merozooplanktonic decapod larvae and ichthyoplankton. Biomass is high and there are strong crossshelf gradients in the Gulf. Zooplankton collected in the southern Pacific coast (close to Isla del Caño) is also dominated by copepods, while Bahía Coronado has a mixed zooplankton composition of oceanic and coastal transition waters. In Golfo Dulce, zooplankton is highly diverse and dominated by copepods, appendicularians, and ostracods. About 35 % of daily primary production is consumed by microzooplankton, and zooplankton adapt to anomalous conditions of El Niño-Southern Oscillation (ENSO). Coco´s Island, and other oceanic islands in the Eastern Tropical Pacific are “hot spot” of zooplankton diversity, where > 160 zooplankton species have been reported (predominantly copepods). The biomass is dominated by mesozooplankton, and new species records for the Eastern Tropical Pacific have been found in this insular ecosystem. In the other hand, early works of 1980 carried out at Caribbean coast (Cahuita National Park), show a considerably low zooplankton diversity and abundance while research at the end of the 2000 decade recognized a significant increase in zooplankton diversity, specially fish larvae. Recent zooplankton studies have added six new copepod species and several new records of species from different taxonomic groups such as appendicularians, amphipods, chaetognats, euphausiids, gastropods, and polychaetes. Future work should focus on monthly long-term monitoring programs to investigate the effects of ocean acidification and the trophic dynamics associated with fisheries. Alike, longterm studies are needed to see trends of change in planktonic communities, especially comparing areas under human activity in the coastal zone (tourism, port, urban development) with protected areas as targets for study. An increase of sampling efforts must be done in the relatively understudied Northern Caribbean coast.

Clave dicotómica para la identificación de Apendicularias en el PacíficoTropical Oriental y Mares Interamericanos, con un listado de especies para Costa Rica

Although appendicularians are relevant primary consumers and are part of every zooplankton community, there is a lack of information on the species present in different ocean regions. Thus, regional identification guides are useful to develop datasets with high taxonomic resolution. Appendicularian species were identified in 33 epipelagic samples of zooplankton collected in several locations of Costarican waters. Eighteen appendicularian species were identified, of which 15 were found in the Pacific and only three in the Caribbean. Seven species are new records for Costa Rican Pacific waters (Appendicularia sicula, Fritillaria charybdae, F. cf. pacifica, F. tenella, F. pellucida f. omani, Oikoipleura fusiformis f. cornutogastra and Pelagopleura verticalis). Data for each species distribution in Costa Rica is presented together with a key for the identification of appendicularian species recorded in the Inter-American seas and the Eastern Tropical Pacific.

Natural ocean acidification at Papagayo upwelling system (north Pacific Costa Rica): implications for reef development

Abstract. Numerous experiments have shown that ocean acidification impedes coral calcification, but knowledge about in situ reef ecosystem response to ocean acidification is still scarce. Bahía Culebra, situated at the northern Pacific coast of Costa Rica, is a location naturally exposed to acidic conditions due to the Papagayo seasonal upwelling. We measured pH and pCO2 in situ during two non-upwelling seasons (June 2012, May–June 2013), with a high temporal resolution of every 15 and 30 min, respectively, using two Submersible Autonomous Moored Instruments (SAMI-pH, SAMI-CO2). These results were compared with published data from the 2009 upwelling season. Findings revealed that the carbonate system in Bahía Culebra shows a high temporal variability. Incoming offshore waters drive intra- and interseasonal changes. Lowest pH (7.8) and highest pCO2 (658.3 µatm) values measured during a cold-water intrusion event in the non-upwelling season were similar to those minimum values reported from upwelling season (pH = 7.8, pCO2 = 643.5 µatm), unveiling that natural acidification also occurs sporadically in the non-upwelling season. This affects the interaction of photosynthesis, respiration, calcification and carbonate dissolution and the resulting diel cycle of pH and pCO2 in the reefs of Bahía Culebra. During the non-upwelling season, the aragonite saturation state (Ωa) rises to values of > 3.3 and during the upwelling season falls below 2.5. The Ωa threshold values for coral growth were derived from the correlation between measured Ωa and coral linear extension rates which were obtained from the literature and suggest that future ocean acidification will threaten the continued growth of reefs in Bahía Culebra. These data contribute to building a better understanding of the carbonate system dynamics and coral reefs' key response (e.g., coral growth) to natural low-pH conditions, in upwelling areas in the eastern tropical Pacific and beyond.

Initial limnological observations at five small lakes in southern Pacific Costa Rica

Costa Rica has hundreds of lakes, many of which have never been described or sampled by limnologists. Here we summarize initial observations of five small (0.2–1.7ha) lakes located at low elevation (365–490m) in the cantón of Buenos Aries. We collected basic limnological data and samples during visits in 2013 and 2014, and compiled environmental and archaeological data for their surroundings as a contribution to the documentation of lake diversity in Costa Rica, and to support parallel investigations of indicators of environmental history preserved in the sediments of the lakes. Lagunas Carse, Los Mangos, Danta, and Ojo de Agua all appear to owe their origin to landslide events, while Laguna Junquillo is an artificial impoundment. Radiocarbon dates on plant macrofossils near the bases of sediment cores from three of the natural lakes provide minimum ages for lake formation; results indicate that Laguna Los Mangos formed over 4 100 years ago, while Laguna Danta formed prior to 1 320 CE and Laguna Carse formed ca. 1 550 CE, near the time of the Spanish Conquest. More than two dozen archaeological sites are located within 1–3Km of the natural lakes, documenting pre-Columbian human occupation and likely use of lake resources. Lake water temperatures and water chemistry were in keeping with observations at lakes throughout Costa Rica. All five lakes are probably polymictic lakes that turn over frequently; none evinced stratification. The surface lake sediments showed similar organic matter content (22,1–28,8%), with values falling near the middle of the range of lakes previously sampled in Costa Rica. Phytoplankton samples included taxa previously reported from small lowland lakes, but differed between lakes and included dominant taxa that were subdominant or uncommon at other lakes surveyed. Our investigation adds to knowledge of lake characteristics and diversity in Costa Rica, and provides benchmarks for assessing future changes in these lakes and their watersheds resulting from human activity, natural disturbances, and regional and global climate change.

The relationship between humidity, light and the activity pattern of a velvet worm, Epiperipatus sp. (Onychophora: Peripatidae), from Bahía Drake, South Pacific of Costa Rica.

Even though the Onychophora represent a whole phylum, observations of their activity pattern in nature are almost non-existent. Here we report on the relationship between humidity and light and activity pattern of a new species of velvet worm, genus Epiperipatus, from four years of field observations in the South Pacific of Costa Rica. We found that most activity occurs during the driest and darkest nights of the year, in contrast with theoretical predictions.

Six New Tropical Sternaspid Species (Annelida, Sternaspidae) with Keys to Identify Genera and Species.

Sergio I. Salazar-Vallejo (2017) The study of tropical specimens of Sternaspidae (Annelida) in five museum collections allowed the recognition of six undescribed species. The species newly described are Caulleryaspis villamari sp. nov. from Peru, Petersenaspis deani sp. nov. from Pacific Costa Rica, P. harrisae sp. nov. from South Africa, Sternaspis lindae sp. nov. from the Gulf of Panama, S. londognoi sp. nov. from the Southern Caribbean Sea, and S. sherlockae sp. nov. from the Red Sea. Updated keys to identify sternaspid genera, and to species in each genus are included.

Euphausiids (Crustacea: Euphausiacea) from a hotspot of marine biodiversity, Isla del Coco, Costa Rica, Eastern Tropical Pacific

Euphausiids have been well studied in several regions of the Pacific Ocean; however, there is lessinformation regarding euphausiids in Costa Rican waters. We analyzed euphausiid specimens collected aroundIsla del Coco National Park during 2011 and 2012. A total of 130 specimens were analyzed and 13 euphausiidspecies were identified, belonging to four genera and one family. An annotated list of species is presented,with photographs and details for their identification. All species found represent new records for waters aroundIsla del Coco in the Costa Rican Pacific. The most frequent species were Euphausia diomedeae, Euphausiadistinguenda, Nematoscelis gracilis and Stylocheiron affine. Rev. Biol. Trop. 64 (Suppl. 1): S221-S230. Epub2016 Febrary 01.

La explotación del tinte de caracol y la lucha de los indígenas por su preservación en el Pacífico de Costa Rica (siglos XVI al XIX)

La explotación del tinte de caracol y la lucha de los indígenas por su preservación en el Pacífico de Costa Rica (siglos XVI al XIX)

Fatty acids profile and nutritional composition of two tropical diatoms from the Costa Rican Pacific Coast

Microalgae represent an important nutritional source for diverse organisms, therefore, their nutritional value, and more specifically, total lipid and fatty acid contents, must be considered. This study evaluated the nutritional contents and potential growth under controlled conditions of Nitzschia sp. and Chaetoceros sp. Tropical microalgae, isolated from the Gulf of Nicoya, Costa Rica. In both strains, the nutritional composition and the fatty acid profile were evaluated in exponential and stationary phases. With regards to fatty acids, v sp. had more Eicosapentaenoic Acid (EPA) in both the exponential (32.80%) and stationary (27.20%) phases. The results in growth rate, production and biochemical composition indicated two tropical microalgae strains suitable for cultivation under controlled conditions. The studies of the phytoplankton in this geographical area is highly relevant because of its importance in the primary production of nutrients and the importance of finding sources of fatty acids such as the EPA.

Validación de modelos geoestadísticos y convencionales en la determinación de la variación espacial de la fertilidad de suelos del Pacífico Sur de Costa Rica

The study validates geo-statistical and conventional models for a soil fertility data set of the South Pacific agricultural lands in the coastal plains of Costa Rica. A metha-analysis was conducted and a best adjustment semivariogram employed to allow using Kriging interpolation. Statistical analysis included frequency distribution, means estimates, correlations and principal components analysis (CP). Values of selected variables were interpolated by ordinary Kriging following four consecutive validation types: field validation, cross validation, errors calculated for each interpolation of validations, subtraction of errors from original data observations, generation of a new field validation, and subsequent cross validation. Interpolations results were analyzed using error absolute average (PAE), error mean square (PCE), prediction affectivity (E) and determination (r2). The data set included soil available information of the counties Corredores, Golfito and Osa previously planted to oil palm, rice, forest and few other crops (named “cultivos varios”). Soils are mainly of alluvial origin in lower positions but with a little more development in the distal part of the hillsides, to include mainly Inceptisols, Ultisols, Entisols and a few Andisols. Variables investigated include pH, exchangeable acidity, Ca, Mg, K, P, Zn, Cu, Fe and Mn. Results shows high variation coefficients mainly for exchangeable acidity and availability of Mg, K, P, Zn, Cu Fe y Mn. Frequency analysis demonstrated abnormal distributions for all elements and tendencies between 25 and 75 percentiles however but normal for pH values. Mean values of variables by crops showed higher numbers under rice plantations pH (6.0), Ca (26.8 cmol (+) L-1), Mg (10.6 cmol (+) L-1) and Mn (34.2mg L-1). Values for oil palm plantations were significantly higher (α = 005) for exchangeable acidity (0.5 cmol (+) L-1), K (0.8 cmol (+) L-1), P (13.1mg L-1), Zn (2.8mg L-1) y Fe (99.8mg L-1). Spearman correlation analysis found proportional relationships between Ca, Mg, and K and inverse proportional correlation between pH y exchangeable acidity and soil available K and P. Other crops (“cultivos varios”) showed highly variable intermediate values. CP analysis explained 60.8% of nutrients variability in the study area with a relation between forest and other crops among CP1 and CP2 dimensions, probably related to the behavior of K and P under oil palm pH in rice fields. A relationship was also found among dimensions CP2 and CP3 for Fe and Cu under oil palm and pH under other crops. It was determined that soil acidity, pH and availability of Mg and K were strongly related to the nutritional management practices of the different crops and that of Ca particularly to the soil genesis on calcareous materials. Nutrients interpolation validation determined that PAE, PCE, E and r2 values improved prediction after removing interpolation errors. Corss validation after substration of interpolation errors showed the best interpolation adjustment as compared to field validation and both validations, and better estimation not subtracting nutrients distribution errors in the alluvial coastal plains of the South Pacific Costa Rica. It is concluded that the information provided by the maps build after interpolations well represent the special variability of the evaluated variables. This confirm that the tools employed is functional to develop relevant works in the diagnosis of nutrient problems in soils or soil fertility conditions for a region and other s similar with spatially referenced soil data.

Secondary nesting beaches for leatherback turtles on the Pacific coast of Costa Rica

Leatherback turtles ( Dermochelys coriacea ) have declined dramatically in the eastern Pacific Ocean (EP) in recent decades. Traditionally, population assessments have relied on the numbers of turtles on the beaches with the highest abundance of turtles (index beaches) and often disregarded the importance of nesting beaches with smaller, but still regular, numbers of nesting turtles (secondary beaches). We characterize leatherback nesting on secondary beaches throughout Pacific Costa Rica. Nesting distribution was significantly reduced since the 1990s and it currently appears to be constricted to the Santa Elena and Nicoya peninsulas. Over the past five years, nesting abundance on secondary beaches was low, ranging between 0.4 ± 0.5 and 5.3 ± 1.5 females and 3.8 ± 5.2 and 22.8 ± 10.8 nests per beach and per year. There was some exchange of turtles between beaches. The exchange rate (percentage of females that nested at least once on a different beach) ranged between 7% and 28%. While Caletas still registers multiple clutches that are laid by 1-2 females in some years, it may no longer qualify as a secondary beach due to the infrequent nature of nesting events registered recently and the total absence of nests in some of those years. Although nesting abundance is relatively low at secondary beaches, they host at least ~25% of total leatherback nesting abundance in Costa Rica. As the EP leatherback turtle declines, not only do the numbers of nesting turtles decrease but local extirpations are occurring on, previously categorized, secondary beaches. The critically low number of turtles at present may prevent recolonization of sites where they have been extirpated.

Morphology and sediment structures in Golfo Dulce, Costa Rica

Sediment echosounder records (18 KHz) of 14 profiles were made in the fjord-like embayment of Golfo Dulce. Pacific of Costa Rica. to investigate morphology and sediment structure. The NW-SW section includes an oriental fault that is the main internal tectonic characteristic of the Gulf; that has a very steep slope and reaches 170 m in height. Two parallel. but less prominent tectonic faults are also evident on the echographs. The sediments in the flat inner basin consist mainly of turbidites, which reach the deepest part of Golfo Dulce by channels. leaving most of the slope sediments unaffected.

Echinoderm diversity of a tropical estuary in the largest river basin of the Costa Rican Pacific, Eastern Tropical Pacific

Echinoderms within the Eastern Tropical Pacific have mainly been studied in association with coral reefs. Investigations on echinoderms associated with soft-bottoms and estuaries are still scarce. The present study reports on the echinoderm species inhabiting the soft-bottom sediments of shallow-brackish waters adjacent to the largest river basin along the Pacific coast of Costa Rica, Térraba-Sierpe wetland. Nine species were recorded, three of them new records for Costa Rica: Luidia columbia, L. latiradiata, and L. superba. The most common species were L. columbia, Astropecten armatus, A. regalis, and L. latiradiata. This contributes towards current knowledge on the biodiversity of Térraba-Sierpe wetland and should be considered as a baseline upon which to monitor the effects of future impacts on this important mangrove area.

Blown by the wind: the ecology of male courtship display behavior in orchid bees.

Many insects rely on chemical signals to transmit precise information on the location, identity, and quality of potential mates. Chemical signals are often broadcasted at sites with physical properties that maximize signal propagation and signal transmission. Male neotropical orchid bees (Euglossini) perch and display on vertical branches and tree trunks in the forest to expose volatile blends (perfumes) that they previously collected from their environment. Previous studies have shown that the chemical composition of perfume blends is highly differentiated even between closely related species. However, variation in behavioral components of perfume exposure and male display remain poorly understood. We conducted a four-year study on orchid bee display sites (8 species) in pacific Costa Rica, using field observations along with chemical analysis and cage experiments to assess display niche partitioning among sympatric species. We evaluated the influence of physical factors (terrain, wind, light) on the distribution of perch sites and on display behavior, and tested a prediction of the sex pheromone-analogue hypothesis, i.e., that displaying males have above-average quantities or qualities of acquired perfumes. Males of different species displayed in the same general area and sometimes in close proximity to each other, but partitioned the display niche by selecting different perch diameters, display heights, and by displaying at different times of the day. Most perch sites were located inside the forest on elevated ground, especially along ridges, where stronger winds may help disperse perfume signals. Furthermore, the angular position of displaying males on perches was narrowly determined by wind direction, with males being positioned on the downwind side of the perch, where they would be most conspicuous to conspecifics approaching on an odor trail. Although our results generally support the hypothesis that perfumes serve as pheromone analogues, we did not find differences in the perfume composition of males caught at display perches and males captured at chemical baits. This suggests that, while chemical communication is an integral part of orchid bee display, male display activity is not determined by the history of, and success in, volatile acquisition.