Hurricane disturbance drives trophic changes in neotropical mountain stream food webs.

Food webs are complex ecological networks that reveal species interactions and energy flow in ecosystems. Prevailing ecological knowledge on forested streams suggests that their food webs are based on allochthonous carbon, driven by a constant supply of organic matter from adjacent vegetation and limited primary production due to low light conditions. Extreme climatic disturbances can disrupt these natural ecosystem dynamics by altering resource availability, which leads to changes in food web structure and functioning. Here, we quantify the response of stream food webs to two major hurricanes (Irma and María, Category 5 and 4, respectively) that struck Puerto Rico in September 2017. Within two tropical forested streams (first and second order), we collected ecosystem and food web data 6 months prior to the hurricanes and 2, 9, and 18 months afterward. We assessed the structural (e.g., canopy) and hydrological (e.g., discharge) characteristics of the ecosystem and monitored changes in basal resources (i.e., algae, biofilm, and leaf litter), consumers (e.g., aquatic invertebrates, riparian consumers), and applied Layman's community-wide metrics using the isotopic composition of 13 C and 15 N. Continuous stream discharge measurements indicated that the hurricanes did not cause an extreme hydrological event. However, the sixfold increase in canopy openness and associated changes in litter input appeared to trigger an increase in primary production. These food webs were primarily based on terrestrially derived carbon before the hurricanes, but most taxa (including Atya and Xiphocaris shrimp, the consumers with highest biomass) shifted their food source to autochthonous carbon within 2 months of the hurricanes. We also found evidence that the hurricanes dramatically altered the structure of the food web, resulting in shorter (i.e., smaller food-chain length), narrower (i.e., lower diversity of carbon sources) food webs, as well as increased trophic species packing. This study demonstrates how hurricane disturbance can alter stream food webs, changing the trophic base from allochthonous to autochthonous resources via changes in the physical environment (i.e., canopy defoliation). As hurricanes become more frequent and severe due to climate change, our findings greatly contribute to our understanding of the mechanisms that maintain forested stream trophic interactions amidst global change.

A global agenda for advancing freshwater biodiversity research.

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation.

Mayfly emergence production and body length response to hydrology in a tropical lowland stream.

BACKGROUND: Hydrological impacts on aquatic biota have been assessed in numerous empirical studies. Aquatic insects are severely affected by population declines and consequent diversity loss. However, many uncertainties remain regarding the effects of hydrology on insect production and the consequences of energy transfer to the terrestrial ecosystem. Likewise, sublethal effects on insect morphology remain poorly quantified in highly variable environments. Here, we characterized monthly fluctuation in benthic and emerged biomass of Ephemeroptera in a tropical lowland stream. We quantified the proportion of mayfly production that emerges into the riparian forest. We also examined the potential morphological changes in Farrodes caribbianus (the most abundant mayfly in our samples) due to environmental stress. METHODS: We collected mayflies (nymphs and adults) in a first-order stream in Costa Rica. We compared benthic and adult biomass from two years' worth of samples, collected with a core sampler (0.006 m2) and a 2 m2-emergence trap. The relationship between emergence and annual secondary production (E/P) was used to estimate the Ephemeroptera production that emerged as adults. A model selection approach was used to determine the relationship between environmental variables that were collected monthly and the emergent biomass. To determine potential departures from perfect bilateral symmetry, we evaluated the symmetry of two morphological traits (forceps and forewing) of F. caribbianus adults. We used Spearman's rank correlation coefficients (ρ) to examine potential changes in adult body length as a possible response to environmental stress. RESULTS: Benthic biomass was variable, with peaks throughout the study period. However, peaks in benthic biomass did not lead to increases in mayfly emergence, which remained stable over time. Relatively constant mayfly emergence suggests that they were aseasonal in tropical lowland streams. Our E/P estimate indicated that approximately 39% and 20% (for 2002 and 2003, respectively) of the nymph production emerged as adults. Our estimated proportion of mayfly production transferred to terrestrial ecosystems was high relative to reports from temperate regions. We observed a strong negative response of F. caribbianus body length to increased hydrology (Spearman: ρ = -0.51, p < 0.001), while slight departures from perfect symmetry were observed in all traits. CONCLUSION: Our two years study demonstrates that there was large temporal variability in mayfly biomass that was unrelated to hydrological fluctuations, but potentially related to trophic interactions (e.g., fish predation). Body length was a good indicator of environmental stress, which could have severe associated costs for mayfly fitness in ecosystems with high temporal variation. Our results highlight the complex ecological and evolutionary dynamics of tropical aquatic insects, and the intricate connection between aquatic and terrestrial ecosystems.

Freshwater research in Latin America: Current research topics, challenges, and opportunities

o Introduction: Freshwater research in Latin America has been increasing in recent years, with a large participation of scientists based on local institutions. However, researchers in the region are facing diverse challenges, and we lack a regional overview of the status of freshwater research. Objective: To address this, we surveyed researchers in the region to assess the current activity and challenges faced by the scientific community. We were interested in understanding (1) the type of research currently taking place in the region, (2) the major research gaps, as viewed by local researchers, and (3) the main limitations or obstacles slowing the development of freshwater science in the region. Methods: We prepared a questionnaire with 26 questions regarding the background of participants, their ongoing research priorities, the products generated from their research, and the major limitations they are facing as researchers. Results: We obtained 105 answers from researchers in 19 Latin American countries. Some of the important trends identified included: (1) a focus on stream ecosystems under agricultural and natural forest; (2) emphasis on biodiversity assessment and species inventories; (3) limited ecological research, mostly centered on litter decomposition and food web studies; and (4) communicating research in the form of peer-reviewed papers and reports in gray literature. Major limitations to the scientific activity included: (1) language, with a majority of respondents considering their handling of English a handicap; (2) limited access to research equipment; (3) lack of tools, such as taxonomic keys; and (4) limited research funding. Research needs and priorities resulted in three major areas in need of attention: (1) developing taxonomy and systematics; (2) improving our current understanding of ecology and natural history; and (3) understanding species distributions and biodiversity patterns. Conclusions: Latin America has an active community of scientists. There is a need to diversify research topics, without abandoning traditional research areas (e.g., taxonomy, species distribution). We advocate for more collaboration among scientists with similar research goals, regardless of their affiliation. Improving communication and collaboration among universities and countries within Latin America will certainly facilitate overcoming obstacles and will help shaping a brighter future for freshwater research, and sciences in general, in the region.

o Introducción: las investigaciones en ecosistemas de agua dulce en América Latina han aumentado en los últimos años, con gran participación de científicos establecidos en instituciones locales. Los investigadores en la región se enfrentan a una variedad de desafíos y carecemos de una descripción regional del estado de la investigación en agua dulce. Objetivo: para abordar esto, encuestamos a investigadores de la región para evaluar las líneas de investigación y los desafíos que enfrenta la comunidad científica. Estábamos interesados ​​en comprender (1) el tipo de investigación que se está llevando a cabo actualmente en la región, (2) las principales brechas de investigación, según lo visto por los investigadores locales, y (3) las principales limitaciones u obstáculos que retrasan el desarrollo de la ciencia del agua dulce en la región. Métodos: preparamos un cuestionario con 26 preguntas sobre los antecedentes de los encuestados, sus prioridades actuales de investigación, los productos generados a partir de su investigación, y las principales limitaciones que enfrentan como investigadores. Resultados: obtuvimos 105 respuestas de investigadores en 19 países latinoamericanos. Algunas de las tendencias más importantes incluyeron: (1) un enfoque en ecosistemas fluviales, principalmente bajo los usos de tierra agrícola y de bosque; (2) énfasis en la evaluación de la biodiversidad y los inventarios de especies; (3) la limitada investigación ecológica está centrada en la descomposición de hojarasca y los estudios de la red alimentaria; y (4) la comunicación de la investigación se da a través de artículos científicos revisados por pares e informes técnicos en literatura gris. Las principales limitaciones de la actividad científica incluyen: (1) lenguaje, con la mayoría de los encuestados que consideran que su manejo del inglés es una desventaja; (2) acceso limitado a equipos de investigación; (3) falta de herramientas, tales como claves taxonómicas; y (4) financiamiento de investigación limitado. Las necesidades y prioridades de investigación dieron como resultado tres áreas principales que requieren atención: (1) desarrollar la taxonomía y la sistemática; (2) mejorar nuestra comprensión actual de la ecología y la historia natural; y (3) comprensión de la distribución de especies y patrones de biodiversidad. Conclusiones: América Latina tiene una comunidad activa de científicos. Identificamos la necesidad de diversificar los temas de investigación, sin abandonar áreas tradicionales (e.g., taxonomía, distribución de especies). Abogamos por una mayor colaboración entre los científicos con los objetivos de investigación similares, independientemente de su afiliación. Mejorar la comunicación y la colaboración entre universidades y países de América Latina ciertamente facilitará la superación de obstáculos y ayudará a forjar un futuro más prometedor para la investigación del agua dulce y las ciencias en general en la región.

The description of Anacroneuria suerre sp. nov. from Costa Rica (Plecoptera: Perlidae) and using nymphs in ecotoxicological studies.

The lack of nymph-adult associations limits our knowledge of the ecology, history and sensitivity of aquatic insects. In this study, the new species, Anacroneuria suerre sp. nov is described from Costa Rica based on the male, female, and nymphal stages. We briefly discuss the use of Plecoptera in ecotoxicological studies.

Large-scale climatic phenomena drive fluctuations in macroinvertebrate assemblages in lowland tropical streams, Costa Rica: The importance of ENSO events in determining long-term (15y) patterns.

Understanding how environmental variables influence the distribution and density of organisms over relatively long temporal scales is a central question in ecology given increased climatic variability (e.g., precipitation, ENSO events). The primary goal of our study was to evaluate long-term (15y time span) patterns of climate, as well as environmental parameters in two Neotropical streams in lowland Costa Rica, to assess potential effects on aquatic macroinvertebrates. We also examined the relative effects of an 8y whole-stream P-enrichment experiment on macroinvertebrate assemblages against the backdrop of this long-term study. Climate, environmental variables and macroinvertebrate samples were measured monthly for 7y and then quarterly for an additional 8y in each stream. Temporal patterns in climatic and environmental variables showed high variability over time, without clear inter-annual or intra-annual patterns. Macroinvertebrate richness and abundance decreased with increasing discharge and was positively related to the number of days since the last high discharge event. Findings show that fluctuations in stream physicochemistry and macroinvertebrate assemblage structure are ultimately the result of large-scale climatic phenomena, such as ENSO events, while the 8y P-enrichment did not appear to affect macroinvertebrates. Our study demonstrates that Neotropical lowland streams are highly dynamic and not as stable as is commonly presumed, with high intra- and inter-annual variability in environmental parameters that change the structure and composition of freshwater macroinvertebrate assemblages.

Sobre ensambles y ensamblajes ecológicos - respuesta a Monge-Nájera / Ecological ensembles and assemblages - a reply to Monge-Nájera

ResumenEvaluar críticamente la terminología que usamos en ecología es importante para evitar el uso de palabras que no ayudan a facilitar la comunicación científica. En este trabajo contestamos el comentario de Monge-Najera sobre el uso de los términos ensamble y ensamblaje, argumentando que estas palabras son válidas y útiles en el idioma español.Además, ambos términos tienen su lugar en la ecología, por lo que proveemos información para usarlos en un contexto ecológico apropiado.

AbstractCritical evaluation of terminology use in ecology is important to avoid using jargon that helps little to facilitate communication. Here we reply to Monge-Najera’s comment on the use of the terms ensemble and assemblage, we argue for the use of the words ensamble and ensamblaje in Spanish. In addition, both terms have a proper place in ecology and we provide a case for their use in proper ecological context. Rev. Biol. Trop. 64 (2): 817-819. Epub 2016 June 01.

[Ecological ensembles and assemblages - a reply to Monge-Nájera]. / Sobre ensambles y ensamblajes ecológicos - respuesta a Monge-Nájera.

Critical evaluation of terminology use in ecology is important to avoid using jargon that helps little to facilitate communication. Here we reply to Monge-Najera's comment on the use of the terms ensemble and assemblage, we argue for the use of the words ensamble and ensamblaje in Spanish. In addition, both terms have a proper place in ecology and we provide a case for their use in proper ecological context.

A new species of Anacroneuria Klapálek 1909 (Plecoptera: Perlidae) and notes on the altitudinal distribution of the genus in Costa Rica.

Anacroneuria is the most widespread genus of Perlidae throughout the Neotropical region and 30 species have been reported from Costa Rica. In this paper, we describe and illustrate a new species from a high elevation cloud forest, A. quetzali sp.n., increasing to 31 the number of described species for Costa Rica. In addition, we examine the altitudinal distribution of Anacroneuria in Costa Rica to determine possible patterns, using the data available on its altitudinal range (10-2700 masl). We divided the elevational range in seven categories, using 500 m intervals. We found that most species (90.3%) are distributed in elevations that range from 500 to 1500 masl, followed by low-elevations (35.5%). Interestingly, despite the fact that Plecoptera are known to inhabit clean, fast flowing water at high elevations, only 16.1% of the species have been found at high elevations in Costa Rica (above 2000 masl). Thus, it seems that most Anacroneuria species are distributed in middle elevations, which are the areas that have a high diversity of freshwater habitats.

Three new species of Anacroneuria Klapálek (Plecoptera: Perlidae) from Panama.

In Central America, the Plecoptera is represented by the genera Anacroneuria and Perlesta, both from the Perlidae family. A total of 45 species have been reported for the region, of which 16 have been found in Panama, all of the genus Anacroneuria. Three new species for Panama are described in this study: Anacroneuria darien, A. embera, and A. laru.

New records of Anacroneuria Klapálek, 1909 (Plecoptera: Perlidae) for Central America.

The perlid genus Anacroneuria is the most widely distributed stonefly occurring in the Neotropics. Regional studies of this genus were made early in the last century, whereas local taxonomic and distributional studies have recently increased. In this study, we provide new Central American records for four species of Anacroneuria. Anacroneuria choco Stark & Bersosa 2006, A. costana (Navás 1924), A. hacha Stark 1998, and A. laru Gutiérrez-Fonseca 2015 are newly reported including new range extensions.

[Studies on Latin American freshwater macroinvertebrates: recent advances and future directions]. / Estudios sobre macroinvertebrados acuáticos en América Latina: avances recientes y direcciones futuras.

Latin America is an active scientific research area, in particular with respect to the study of freshwater macroinvertebrates. The present serves as an introduction to a special issue that highlights recent research projects on macroinvertebrates in Latin America. As part of this introduction, we conducted a literature analysis of the last 14 years of publications from the region that highlights the steady increase in publications on macroinvertebrates. Most studies from 2000-2013 were conducted in Brazil, Colombia, Argentina, and Costa Rica, and were focused on taxonomy and different issues related to biodiversity and distribution. There was a tendency for the use of local low-impact journals, but high impact publications were also found. This special issue contributes with 18 studies conducted in eight different countries. Two major topics are covered in the special issue, the ecology and natural history of aquatic macroinvertebrates and their use in the evaluation of anthropogenic impacts to aquatic ecosystems. Based on the literature review and contributions included in the issue, we discuss research needs for the region. Identified needs include: (1) to continue emphasizing taxonomic research, (2) assess mechanisms responsible for changes in biodiversity, (3) assess the role of macroinvertebrates in ecosystem processes and function, (4) improve biomonitoring efforts beyond unimetric indices, (5) the need for an ecosystem perspective, and (6) establishing long-term studies. This special issue is an initial effort to advance our knowledge on freshwater macroinvertebrates in Latin America.

Functional feeding groups of aquatic insect families in Latin America: a critical analysis and review of existing literature.

Aquatic macroinvertebrates are involved in numerous processes within aquatic ecosystems. They often have important effects on ecosystem processes such as primary production (via grazing), detritus breakdown, and nutrient mineralization and downstream spiraling. The functional feeding groups (FFG) classification was developed as a tool to facilitate the incorporation of macroinvertebrates in studies of aquatic ecosystems. This classification has the advantage of combining morphological characteristics (e.g., mouth part specialization) and behavioral mechanisms (e.g., way of feeding) used by macroinvertebrates when consuming resources. Although recent efforts have greatly advanced our ability to identify aquatic macroinvertebrates, there is limited information on FFG assignment. Furthermore, there has been some variation in the use of the FFG classification, in part due to an emphasis on using gut content analysis to assign FFG, which is more appropriate for assigning trophic guilds. Thus, the main goals of this study are to (1) provide an overview of the value of using the FFG classification, (2) make an initial attempt to summarize available information on FFG for aquatic insects in Latin America, and (3) provide general guidelines on how to assign organisms to their FFGs. FFGs are intended to reflect the potential effects of organisms in their ecosystems and the way they consume resources. Groups include scrapers that consume resources that grow attached to the substrate by removing them with their mouth parts; shredders that cut or chew pieces of living or dead plant material, including all plant parts like leaves and wood; collectors-gatherers that use modified mouth parts to sieve or collect small particles (< 1 mm) accumulated on the stream bottom; filterers that have special adaptations to remove particles directly from the water column; and predators that consume other organisms using different strategies to capture them. In addition, we provide details on piercers that feed on vascular plants by cutting or piercing the tissue using sharp or chewing mouth parts and consume plant liquids. We also provide a list of families of aquatic insects in Latin America, with an initial assignment to FFGs. We recommended caution when assigning FFGs based on gut contents, as it can provide misleading information. Overall, FFG is a very useful tool to understand the role of aquatic macroinvertebrates in stream ecosystems and comparisons among studies will benefit from consistency in their use.

Application of the BMWP-Costa Rica biotic index in aquatic biomonitoring: sensitivity to collection method and sampling intensity.

The use of aquatic macroinvertebrates as bio-indicators in water quality studies has increased considerably over the last decade in Costa Rica, and standard biomonitoring methods have now been formulated at the national level. Nevertheless, questions remain about the effectiveness of different methods of sampling freshwater benthic assemblages, and how sampling intensity may influence biomonitoring results. In this study, we compared the results of qualitative sampling using commonly applied methods with a more intensive quantitative approach at 12 sites in small, lowland streams on the southern Caribbean slope of Costa Rica. Qualitative samples were collected following the official protocol using a strainer during a set time period and macroinvertebrates were field-picked. Quantitative sampling involved collecting ten replicate Surber samples and picking out macroinvertebrates in the laboratory with a stereomicroscope. The strainer sampling method consistently yielded fewer individuals and families than quantitative samples. As a result, site scores calculated using the Biological Monitoring Working Party-Costa Rica (BMWP-CR) biotic index often differed greatly depending on the sampling method. Site water quality classifications using the BMWP-CR index differed between the two sampling methods for 11 of the 12 sites in 2005, and for 9 of the 12 sites in 2006. Sampling intensity clearly had a strong influence on BMWP-CR index scores, as well as perceived differences between reference and impacted sites. Achieving reliable and consistent biomonitoring results for lowland Costa Rican streams may demand intensive sampling and requires careful consideration of sampling methods.

Estudios sobre macroinvertebrados acuáticos en América Latina: avances recientes y direcciones futuras

Studies on Latin American freshwater macroinvertebrates: recent advances and future directions. Latin America is an active scientific research area, in particular with respect to the study of freshwater macroinvertebrates. The present serves as an introduction to a special issue that highlights recent research projects on macroinvertebrates in Latin America. As part of this introduction, we conducted a literature analysis of the last 14 years of publications from the region that highlights the steady increase in publications on macroinvertebrates. Most studies from 2000-2013 were conducted in Brazil, Colombia, Argentina, and Costa Rica, and were focused on taxonomy and different issues related to biodiversity and distribution. There was a tendency for the use of local low-impact journals, but high impact publications were also found. This special issue contributes with 18 studies conducted in eight different countries. Two major topics are covered in the special issue, the ecology and natural history of aquatic macroinvertebrates and their use in the evaluation of anthropogenic impacts to aquatic ecosystems. Based on the literature review and contributions included in the issue, we discuss research needs for the region. Identified needs include: (1) to continue emphasizing taxonomic research, (2) assess mechanisms responsible for changes in biodiversity, (3) assess the role of macroinvertebrates in ecosystem processes and function, (4) improve biomonitoring efforts beyond unimetric indices, (5) the need for an ecosystem perspective, and (6) establishing long-term studies. This special issue is an initial effort to advance our knowledge on freshwater macroinvertebrates in Latin America. Rev. Biol. Trop. 62 (Suppl. 2): 9-20. Epub 2014 April 01.

América Latina es una región bastante activa en cuanto a la investigación científica, en particular con respecto al estudio de macroinvertebrados de agua dulce. La presente es una introducción al número especial que incluye proyectos recientes en América Latina. Como parte de esta introducción, realizamos un análisis de la literatura publicada en los últimos 14 años, la cual tiene un aumento continuo en las publicaciones sobre macroinvertebrados. La mayoría de los estudios en el periodo 2000-2013 fueron realizados en Brasil, Colombia, Argentina, y Costa Rica; y se enfocaron en la taxonomía y temas relacionados con la biodiversidad y la distribución. Se observó una tendencia a publicar en revistas de bajo impacto, pero también se encontraron publicaciones de alto impacto. El número especial incluye 18 trabajos de ocho países. Los temas principales fueron ecología e historia natural de los macroinvertebrados acuáticos y su uso en la evaluación de impactos antropogénicos sobre los ecosistemas acuáticos. Usando la revisión y las publicaciones de este suplemento discutimos algunas necesidades de investigación para la región, principalmente: (1) continuar con los estudios taxonómicos, (2) determinar los mecanismos responsables por los cambios en biodiversidad, (3) evaluar el papel de los macroinvertebrados en los procesos ecológicos, (4) llevar los esfuerzos de biomonitoreo más allá de los métodos unimétricos, (5) implementar una visión de ecosistema, y (6) establecer estudios a largo plazo. Este suplemento representa un esfuerzo inicial para mejorar nuestro conocimiento sobre los macroinvertebrados de agua dulce de América Latina.

Functional feeding groups of aquatic insect families in Latin America: a critical analysis and review of existing literature

Aquatic macroinvertebrates are involved in numerous processes within aquatic ecosystems. They often have important effects on ecosystem processes such as primary production (via grazing), detritus breakdown, and nutrient mineralization and downstream spiraling. The functional feeding groups (FFG) classification was developed as a tool to facilitate the incorporation of macroinvertebrates in studies of aquatic ecosystems. This classification has the advantage of combining morphological characteristics (e.g., mouth part specialization) and behavioral mechanisms (e.g., way of feeding) used by macroinvertebrates when consuming resources. Although recent efforts have greatly advanced our ability to identify aquatic macroinvertebrates, there is limited information on FFG assignment. Furthermore, there has been some variation in the use of the FFG classification, in part due to an emphasis on using gut content analysis to assign FFG, which is more appropriate for assigning trophic guilds. Thus, the main goals of this study are to (1) provide an overview of the value of using the FFG classification, (2) make an initial attempt to summarize available information on FFG for aquatic insects in Latin America, and (3) provide general guidelines on how to assign organisms to their FFGs. FFGs are intended to reflect the potential effects of organisms in their ecosystems and the way they consume resources. Groups include scrapers that consume resources that grow attached to the substrate by removing them with their mouth parts; shredders that cut or chew pieces of living or dead plant material, including all plant parts like leaves and wood; collectors-gatherers that use modified mouth parts to sieve or collect small particles (<1mm) accumulated on the stream bottom; filterers that have special adaptations to remove particles directly from the water column; and predators that consume other organisms using different strategies to capture them. In addition, we provide details on piercers that feed on vascular plants by cutting or piercing the tissue using sharp or chewing mouth parts and consume plant liquids. We also provide a list of families of aquatic insects in Latin America, with an initial assignment to FFGs. We recommended caution when assigning FFGs based on gut contents, as it can provide misleading information. Overall, FFG is a very useful tool to understand the role of aquatic macroinvertebrates in stream ecosystems and comparisons among studies will benefit from consistency in their use. Rev. Biol. Trop. 62 (Suppl. 2): 155-167. Epub 2014 April 01.

Application of the BMWP-Costa Rica biotic index in aquatic biomonitoring: sensitivity to collection method and sampling intensity

The use of aquatic macroinvertebrates as bio-indicators in water quality studies has increased considerably over the last decade in Costa Rica, and standard biomonitoring methods have now been formulated at the national level. Nevertheless, questions remain about the effectiveness of different methods of sampling freshwater benthic assemblages, and how sampling intensity may influence biomonitoring results. In this study, we compared the results of qualitative sampling using commonly applied methods with a more intensive quantitative approach at 12 sites in small, lowland streams on the southern Caribbean slope of Costa Rica. Qualitative samples were collected following the official protocol using a strainer during a set time period and macroinvertebrates were field-picked. Quantitative sampling involved collecting ten replicate Surber samples and picking out macroinvertebrates in the laboratory with a stereomicroscope. The strainer sampling method consistently yielded fewer individuals and families than quantitative samples. As a result, site scores calculated using the Biological Monitoring Working Party-Costa Rica (BMWP-CR) biotic index often differed greatly depending on the sampling method. Site water quality classifications using the BMWP-CR index differed between the two sampling methods for 11 of the 12 sites in 2005, and for 9 of the 12 sites in 2006. Sampling intensity clearly had a strong influence on BMWP-CR index scores, as well as perceived differences between reference and impacted sites. Achieving reliable and consistent biomonitoring results for lowland Costa Rican streams may demand intensive sampling and requires careful consideration of sampling methods. Rev. Biol. Trop. 62 (Suppl. 2): 275-289. Epub 2014 April 01.

En Costa Rica el uso de macroinvertebrados acuáticos como bioindicadores de la calidad ambiental del agua ha aumentado considerablemente en la última década, y se han aplicado métodos estandarizados a nivel nacional. Sin embargo, aún existe controversia sobre la efectividad de los métodos de muestreo y su intensidad. En este estudio comparamos una metodología cualitativa y otra cuantitativa, en 12 sitios de nueve ríos localizados en la cuenca baja del río Sixaola, al sur de la vertiente del Caribe de Costa Rica. Muestras cualitativas fueron recolectadas con un colador durante un período de tiempo establecido y los macroinvertebrados fueron separados en el campo. En el muestreo cuantitativo se recolectaron diez muestras utilizando un Surber y los macroinvertebrados fueron separados en el laboratorio utilizando con esteroscopio. El colador produjo un número menor de individuos y familias que las muestras cuantitativas. Como resultado, la puntuación del índice biótico Biological Monitoring Working Party-Costa Rica (BMWP-CR) en cada sitio dependió del método. La categoría de calidad de agua con ese índice también diferió entre los dos métodos en 11 de los 12 sitios en 2005, y en 9 de los 12 sitios en 2006. La intensidad de muestreo claramente tuvo una fuerte influencia en los resultados del índice BMWP-CR, así como diferencias entre sitios de referencia y los sitios afectados. Debido a la coherencia en los resultados es posible aceptar el método cuantitativo pero con una cantidad prudente de repeticiones en estudios de biomonitoreo acuático.

[Freshwater macroinvertebrates from Cocos Island, Costa Rica: species and comparison with other islands of the Eastern Tropical Pacific]. / Macroinvertebrados dulceacuícolas de la Isla del Coco, Costa Rica: especies y comparación con otras islas del Pacifico Tropical Oriental.

Freshwater macroinvertebrates from Cocos Island, Costa Rica: species and comparison with other islands of the Eastern Tropical Pacific. Cocos Island is an oceanic island in the Eastern Pacific, at 496km from Cabo Blanco, Costa Rica. This 24 km2 island is surrounded by a protected marine area of 9640 km2. it was declared National Park in 1978 and a World Heritage by UNESCO in 1997. Freshwater macroinvertebrate fauna was collected in 20 sites covering three rivers (Genio, Chatam and Sucio) and two creeks (Minuto and an unnamed creek behind the park rangers' house). Tank bromeliads or phytotelmata were also examined for aquatic macroinvertebrates. Physicochemical parameters were determined in 13 study sites. Additionally, a comparison with other islands in the Eastern Tropical Pacific was conducted to determine the most important factors controlling the diversity in Tropical Pacific islands. A total of 455 individuals were collected belonging to 20 taxa (mostly identified to genus level) from 15 families of aquatic insects. Other macroinvertebrates such as Palaemonid shrimps, Hidrachnida and Oligochaeta were also collected. The family Staphylinidae (Coleoptera) was the most abundant, followed by Chironomidae (Diptera). Diptera was the order of insects with the highest taxonomic richness. A relationship between distance and the number of families was observed supporting the premises of the Theory of island Biogeography. This relationship was improved by correcting area by island elevation, indicating that mountainous islands had the richest faunas, potentially due to high cloud interception that feeds freshwater environments favoring the establishment of aquatic fauna. Physicochemical variables were similar in all sites, possibly due to the geology and the absence of significant sources of pollution on the island.

Macroinvertebrados dulceacuícolas de la Isla del Coco, Costa Rica: especies y comparación con otras islas del Pacífico Tropical Oriental / Freshwater macroinvertebrates from Cocos Island, Costa Rica: species and comparison with other islands of the Eastern Tropical Pacific

Cocos Island is an oceanic island in the Eastern Pacific, at 496km from Cabo Blanco, Costa Rica. This 24km² island is surrounded by a protected marine area of 9 640km². It was declared National Park in 1978 and a World Heritage by UNESCO in 1997. Freshwater macroinvertebrate fauna was collected in 20 sites covering three rivers (Genio, Chatam and Sucio) and two creeks (Minuto and an unnamed creek behind the park rangers’ house). Tank bromeliads or phytotelmata were also examined for aquatic macroinvertebrates. Physicochemical parameters were determined in 13 study sites. Additionally, a comparison with other islands in the Eastern Tropical Pacific was conducted to determine the most important factors controlling the diversity in Tropical Pacific islands. A total of 455 individuals were collected belonging to 20 taxa (mostly identified to genus level) from 15 families of aquatic insects. Other macroinvertebrates such as Palaemonid shrimps, Hidrachnida and Oligochaeta were also collected. The family Staphylinidae (Coleoptera) was the most abundant, followed by Chironomidae (Diptera). Diptera was the order of insects with the highest taxonomic richness. A relationship between distance and the number of families was observed supporting the premises of the Theory of island Biogeography. This relationship was improved by correcting area by island elevation, indicating that mountainous islands had the richest faunas, potentially due to high cloud interception that feeds freshwater environments favoring the establishment of aquatic fauna. Physicochemical variables were similar in all sites, possibly due to the geology and the absence of significant sources of pollution on the island.

La Isla del Coco es una isla oceánica localizada en el Pacífico Tropical Oriental a unos 492km de Cabo Blanco. La isla cuenta con un área terrestre de 24km² y un área marina protegida de 9 640km². Fue declarada Parque Nacional en 1978 y Patrimonio de la Humanidad por la UNESCO en 1997. Se realizó una gira de recolecta del 22 de mayo al 12 junio 2008. Se recolectaron macroinvertebrados acuáticos en 20 tramos de tres ríos (Genio, Chatham y Sucio) y dos quebradas (Minuto y quebrada sin nombre atrás de estación de guarda parques). En 13 sitios se toma- ron parámetros fisicoquímicos. En total se recolectaron 455 individuos de 20 táxones de 15 familias de insectos acuáticos y otros macroinvertebrados. La familia Staphylinidae presentó la mayor abundancia seguida por Chironomidae, los dípteros fueron el orden con mayor riqueza taxonómica. Una relación entre distancia y número de familias se observó apoyando en parte la Teoría de Biogeografía de Islas. La relación mejoró al corregir área con elevación, indicando que islas montañosas tenían alta riqueza, posiblemente debido a la mayor intercepción de nubes que alimentan los ambientes dulceacuícolas que favorecen el establecimiento de la fauna acuática. Las variables ambientales fueron similares en todos los sitios.

The larvae of Heteragrion majus Selys and H. atrolineatum Donnelly, with a key to known species from Costa Rica (Odonata: Megapodagrionidae).

The final larval stadium of Heteragrion majus Selys, 1886 and H. atrolineatum Donnelly, 1992 are described and illustrated for the first time, using reared material from Costa Rica, and compared with other species of the genus known from the country. All species were very similar as larvae, but they can be separated by the presence and distribution of antennal setae, spines on the posterior margin of the abdominal segments, and size. A key to separate all five species known for Costa Rica is provided.