Cambios en la comunidad de peces por efecto del desarrollo costero en el Parque Nacional Huatulco (México) / Changes in fish communities from the effect of coastal development in Huatulco National Park (Mexico)

Resumen El incremento del aporte de sedimentos desde tierra derivado del desarrollo costero y urbanización ha producido efectos adversos en la estructura y función de los arrecifes coralinos. El objetivo de este estudio fue conocer la magnitud de disturbios por aportes excesivos de sedimentos en la comunidad íctica de arrecifes coralinos de las bahías Maguey y Violín del Parque Nacional Huatulco (México). Los muestreos de peces se realizaron antes y después de disturbios ocasionados por aportes de sedimentos asociados a obras de desarrollo costero. Como indicadores de cambios en las comunidades de peces se utilizaron el número de especies, diversidad, equidad y dominancia antes y después de la perturbación. El análisis se realizó mediante pruebas de comparación de medias, análisis de similitud (ANOSIM) y análisis de porcentaje de similitud (SIMPER). En ambas localidades, se observó, que, excepto la dominancia, la diversidad, equidad, abundancia y número de especies fueron mayores previos a la perturbación. En Maguey se observaron diferencias significativas en la equidad y dominancia (U=28, p=0.0401; U=24, p=0.0472), así como en la composición de especies y la abundancia (ANOSIM=0.35, p=0.009). El análisis de porcentaje de similitud (SIMPER) indicó que posterior a la perturbación, el 46 % de especies presentaron una disminución en su abundancia, destacó la ausencia de Prionurus laticlavius, así como el decremento en la abundancia de: P. punctatus, Cirrhitichthys oxycephalus, Microspathodon dorsalis, Lutjanus novemfaciatus y Stegates acapulcoensis. La inadecuada planeación y ejecución de proyectos de desarrollo costero que propiciaron aporte excesivo de sedimentos al mar determinaron cambios negativos en las comunidades coralinas de Maguey y Violín, cuyo efecto fue observado en la composición de especies, abundancia, equidad y dominancia de la comunidad de peces de Maguey.(AU)

Abstract Coastal development and urbanization have increased the sediments that are washed from the land surface, producing adverse effects on the structure and functioning of coral reefs. The objective of this study was to identify the degree to which excessive sediments have disturbed the fish community in the coral reefs in the Maguey and Violin bays, located in the Huatulco National Park (Mexico). Fish samples were collected before and after disturbances produced by sediments associated with coastal development projects. Indicators of changes in the fish communities included the number and diversity of species as well as equity and dominance before and after the disturbances. The analysis was performed through means comparison tests, similarity analysis (ANOSIM) and similarity percentage analysis (SIMPER). In both locations, it was observed that the diversity, evenness, abundance and number of species were higher prior to the disturbance, but not for dominance, which shows an inverse pattern. In Maguey, significant differences in evenness and dominance were observed (U = 28, p = 0.0401; U = 24, p = 0.0472), as well as in species composition and abundance (ANOSIM = 0.35, p = 0.009). The similarity percentage analysis (SIMPER) indicated that after the disturbance, more than 46 % of the species showed decreases in average abundance, highlighting the absence of Prionurus laticlavius, as well as the decrease in abundance of: P. punctatus, Cirrhitichthys oxycephalus, Microspathodon dorsalis, Lutjanus novemfaciatus and Stegates acapulcoensis. Inadequate planning and implementation of coastal development projects that contribute to the discharge of excessive sediments into the sea were determinants of negative changes in the coral communities in Maguey and Violin, whose effects could be seen in the composition of the species and the abundance, equity, and dominance of the fish community in Maguey.(AU)

Impact assessment of the introduction of Cichla kelberi in a large Neotropical reservoir and its lateral lagoons (Upper Paraná River Basin, Brazil) / Avaliação do impacto da introdução da Cichla kelberi em um reservatório Neotropical de grande porte e suas lagoas laterais (Bacia do Alto Paraná, Brasil)

Abstract This study aimed to understand how the introduction of Cichla kelberi in Rosana Reservoir (Paranapanema River) affected the native ichthyofauna. Data on the structure of the small fish fauna assemblage were obtained before and after the introduction of this carnivorous species. Samplings were carried out in February and September of 2004, previously to the register of Cichla kelberi in the reservoir, and after its introduction, November of 2004, January, March, May and August of 2005, February and June of 2006, February and July of 2007, February and October of 2008 and February of 2009. A total of 4,693 fish, belonging to 43 different species was sampled between 2004 and 2009. The order Characiformes was the most abundant, followed by Perciformes and Siluriformes. Comparative analyses, before and after the introduction, could not demonstrate significant changes in composition, richness, abundance, biomass, mean length and diversity of fish. Aquatic insects were the main feeding item of C. kelberi, followed by tetragonopterinae fish. Cannibalism was recorded during the whole study period. The results showed that Cichla cannot deeply affect the ichthyofauna assemblages of a large Neotropical reservoir, at least in a short or medium term period after its introduction. The results also allowed concluding that the introduction of C. kelberi in the reservoir is in the phase 3. In this phase, the specie can survive and reproduce in the new environment; however it is not totally established and disseminated. The reasons for the fact that Cichla is still not dominant in Rosana Reservoir could be related to feeding competition, high rate of cannibalism and the presence of large amount of aquatic macrophytes (refuge zones). In spite of the results, the continuous monitoring of the role of non-native species on the local fish fauna is absolutely necessary because the impacts caused by colonization of this undesirable species can be magnified by complex processes, usually correlated with other environmental disturb, especially the negative effects of damming.

Resumo O objetivo deste estudo foi entender como a introdução da Cichla kelberi no reservatório de Rosana (rio Paranapanema) afeta as assembléias de peixes. Dados da estrutura da ictiofauna de pequeno porte foram obtidos antes e após a introdução dessa espécie carnívora. As coletas foram realizadas em fevereiro e setembro de 2004, quando Cichla kelberi, ainda não havia sido registrado no reservatório, e após sua presença, em novembro de 2004, janeiro, março, maio e agosto de 2005, fevereiro e junho de 2006, fevereiro e julho de 2007, fevereiro e outubro de 2008 e fevereiro de 2009. Um total de 4693 peixes, pertencentes a 43 espécies foi amostrado entre 2004 e 2009. A Ordem Characiformes foi a mais abundante, seguida por Perciformes e Siluriformes. Análises comparativas, antes e depois da introdução, não demonstraram mudanças significativas na composição, riqueza, abundância, biomassa, comprimento médio e diversidade dos peixes. Insetos aquáticos constituíram no principal item da alimentação de Cichla kelberi, seguido por peixes tetragonopterídeos. Canibalismo foi registrado durante todo o período de estudo. Os resultados mostraram que Cichla não afeta substancialmente a ictiofauna dos reservatórios neotropicais, pelo menos no curto e médio prazo após sua introdução. Os resultados também permitiram concluir que a introdução de Cichla kelberi se encontra na fase 3. Nessa fase, a espécie pode sobreviver e reproduzir no novo ambiente, contudo ela não está totalmente estabelecida e disseminada. As razões que explicam a ausência de dominância de Cichla no reservatório de Rosana podem estar relacionadas à competição alimentar, a alta taxa de canibalismo e grande quantidade de macrófitas aquáticas (zonas de refúgio). Apesar dos resultados, o monitoramento contínuo do papel das espécies não nativas sobre a ictiofauna local é de extrema importância, pelo fato de que os impactos causados por essas espécies podem ser amplificados, geralmente correlacionados com outros distúrbios ambientais, principalmente efeitos negativos do barramento.

Recurrencia histórica de peces invasores en la Reserva de la Biósfera Sierra de Huautla, México / Historical presence of invasive fish in the Biosphere Reserve Sierra de Huautla, Mexico

Historical presence of invasive fish in the Biosphere Reserve Sierra de Huautla, Mexico. The effects of invasive species on native ecosystems are varied, and these have been linked to the disappearance or decline of native fauna, changes in community structure, modification of ecosystems and as vectors of new diseases and parasites. Besides, the development of trade in species for ornamental use has contributed significantly to the import and introduction of invasive fish in some important areas for biodiversity conservation in Mexico, but the presence of these species is poorly documented. In this study we analyzed the fish community in the Biosphere Reserve Sierra de Huautla by looking at diversity changes in the last 100 years. For this, we used databases of historical records and recent collections for five sites in the Amacuzac river, along the Biosphere Reserve area. We compared the values of similarity (Jaccard index) between five times series (1898-1901, 1945-1953, 1971-1980, 1994-1995 and 2008-2009), and we obtained values of similarity (Bray-Curtis) between the five sites analyzed. In our results we recognized a total of 19 species for the area, nine non-native and ten native, three of which were eliminated for the area. Similarity values between the early days and current records were very low (.27); the major changes in the composition of the fauna occurred in the past 20 years. The values of abundance, diversity and similarity among the sampling sites, indicate the dominance of non-native species. We discuss the role of the ornamental fish trade in the region as the leading cause of invasive introduction in the ecosystem and the possible negative effects that at least four non-native species have had on native fauna and the ecosystem (Oreochromis mossambicus, Amatitlania nigrofasciata, Pterygoplichthys disjunctivus and P. pardalis). There is an urgent need of programs for registration, control and eradication of invasive species in the Sierra de Huautla Biosphere Reserve and biodiversity protection areas in Mexico. Rev. Biol. Trop. 60 (2): 669-681. Epub 2012 June 01.

Los efectos de las especies invasoras en los ecosistemas nativos son variados, y estos se han vinculado con la desaparición o disminución de la fauna nativa, cambios en la estructura de la comunidad, modificación de los ecosistemas y como vectores de nuevas enfermedades y parásitos. El desarrollo del comercio de especies para uso ornamental ha contribuido significativamente a la importación e introducción de peces invasores en algunas áreas importantes para la conservación de la biodiversidad en México, pero la presencia de estas especies está escasamente documentada. En este estudio se analiza la comunidad de peces en la reserva de Biosfera Sierra de Huautla, registrando los cambios en la diversidad en los últimos 100 años. Con bases de datos de registros históricos y recientes colecciones para cinco sitios en el río Amacuzac, que cruza la zona de reserva de la Biosfera, se comparan los valores de similitud (índice de Jaccard) entre cinco series de tiempo (1898-1901, 1945-1953, 1971-1980, 1994-1995 y 2008-2009), así mismo, obtuvimos los valores de similitud (Bray-Curtis) entre los cinco sitios analizados. En total hemos reconocido 19 especies para el área, diez nativas y nueve no nativas, de las cuales tres están extirpadas para el área, los valores de similitud entre los primeros registros y los actuales son muy bajos (0.27), los principales cambios en la composición de la fauna se han producido en los últimos 20 años. Los valores de abundancia, diversidad y similitud entre los sitios de muestreo, indican el predominio de especies no nativas. Discutimos el papel del comercio de peces ornamentales de la región como la principal causa de introducción de invasoras en el ecosistema, y los posibles efectos negativos que han tenido al menos cuatro especies en la fauna nativa y el ecosistema (Oreochromis mossambicus, Amatitlania nigrofasciata, Pterygoplichthys disjunctivus y P. pardalis), se hace notar la ausencia de programas de registro, ...