Temperature-dependent demographic differences in sessile rotifers of the genus Limnias (Rotifera: Gnesiotrocha)

Aim: Rotifer research on sessile taxa has received less attention because they are not easy to identify in fixed samples. In the Lake Xochimilco, a Ramsar site in Mexico City, three morphotypes of L. ceratophylli and a single morphotype of L. cf. melicerta occur in different densities. The aim of this study was to test if temperature was responsible for the differences in the population densities of these morphotypes. Methodology: The present study was carried out using population growth method consisting of 4 treatments (3 morphotypes of L. ceratophylli and one of L. cf. melicerta) at 20 and 25°C. Experiments were carried out in 50 ml glass jars containing 25 ml synthetic medium with Chlorella vulgaris as food. The population growth rates (r) were derived. Analysis of variance (ANOVA) and post-hoc tests were used to quantify the intra-and interspecific differences in the population growth rates. Results: The temperature levels for optimal population growth rates differed among the morphotypes of same species. At 20°C, the morphotype 1 had the highest r (0.23 d-1) similar to that of L. cf. melicerta, while morphotype 3 had the lowest (0.15 d-1). For L. cf. melicerta, the r was higher at 25°C than at 20°C. Of three morphotypes of L. ceratophylli, morphotype 3 had the highest r at 25°C similar to that of L. cf. melicerta at same temperature. Interpretation: There were significant differences among growth patterns within the morphotypes of L. ceratophylli, depending on culture temperature. These trends highlight the relative importance of environmental variables in differentiating morphotypes of a sessile species complex which could explain their possible seasonal changes in the natural waterbodies.

A case of successful restoration of a tropical wetland evaluated through its Odonata (Insecta) larval assemblage

etlands are important wildlife habitats that also provide vital services for human societies. Unfortunately, they have been disappearing due to human activities such as conversion to farmland, pollution, habitat fragmentation, invasion of alien species, and inappropriate management, resulting in declines in species diversity, wildlife habitat quality, and ecosystem functions and services. In some countries, many programs and actions have been undertaken to reverse the rate of wetland loss by restoring, creating and constructing new wetlands. We report on the assessment of Odonata larvae from a tropical and putatively restored wetland located in the La Mancha Biological Station, CICOLMA (LM, Ramsar site #1336), Veracruz, Mexico. Larval surveys were performed during the 2010 and 2011 dry and rainy seasons in both LM and a reference site, Cansaburro (CB), located approximately 2 km South of LM. Twelve samples were collected during each survey using a D-frame aquatic net (0.2 mm mesh size), sweeping 1 m2 areas along shorelines using a random design. The effect of site, season and year on Odonata larval abundance was explored and diversity and abundance patterns of the assemblages were compared. A total of 3 718 larvae from 25 species (five Zygoptera and 20 Anisoptera) in 14 genera and three families were collected from both wetlands. Species number was equal in both wetlands although abundance was significantly higher in LM. Renyi´s diversity profiles and species abundance patterns (rank abundance curves) in both sites were similar, suggesting an apparent recovery at LM. Differences in species composition (sites shared 13 species), and species dominance between both assemblages were observed and were related to differences in the aquatic plant structure between both wetlands as a result of extensive plant management in LM and cattle grazing in CB. Most evidence derived from this work shows that the LM wetland may be recovered. Rev. Biol. Trop. 63 (4): 1043-1058. Epub 2015 December 01.

os humedales son hábitats importantes para la vida silvestre y también proporcionan servicios vitales para la sociedad que, por desgracia, han ido desapareciendo debido al uso del suelo que produce una disminución en la diversidad de especies, la calidad del hábitat de vida silvestre, y de la función de los ecosistemas. En algunos países se han llevado a cabo programas y acciones para revertir la tasa de pérdida de los humedales mediante la restauración, la creación y la construcción de nuevos humedales. En este trabajo se reporta un estudio numérico de las larvas de odonatos de un humedal tropical asumido como restaurado, localizado en la Estación de Biología La Mancha, CICOLMA (LM, sitio Ramsar # 1336), Veracruz, México. Los muestreos de las larvas se realizaron durante las estaciones de secas y lluvias de 2010 y 2011 tanto en LM como en el sitio de referencia Cansaburro (CB) situado a unos 2 km al sur de LM. Se tomaron doce muestras al azar en las orillas durante cada recolecta en cada sitio utilizando una red acuática D-net (abertura de malla de 0.2 mm) barriendo una área aproximada de 1 m2. El efecto del sitio, la temporada y el año sobre la abundancia de larvas fue explorado y los patrones de diversidad y abundancia de ambas comunidades fueron comparadas. Un total de 3 718 larvas de 25 especies (cinco Zygoptera y 20 Anisoptera) de 14 géneros y tres familias se obtuvieron de ambos humedales. El número de especies fue igual en ambos humedales aunque la abundancia fue significativamente mayor en LM. Los perfiles de diversidad de Renyi y los patrones de abundancia de especies (curvas de rango abundancia) en ambos sitios fueron similares sugiriendo una evidente recuperación de LM. Las diferencias observadas en la composición de especies (los sitios compartieron 13 especies) y la dominancia de las especies entre ambas comunidades se explica con base en las diferencias en la estructura vegetal acuática entre los dos humedales que es principalmente el resultado de una amplio manejo en LM y del pastoreo de ganado en CB. La mayoría de las pruebas derivadas de este trabajo muestran que el humedal de LM puede estar recuperado.

Climate Change Challenges for Sustainable Coastal Wetland Management in Xuan Thuy Ramsar Site, Vietnam.

Climate change has been recognized as a global threat and is already affecting ecosystems such as coastal wetlands. With more than 3,200 km of coastline, wetlands are the dominant ecosystem in Vietnam. This country is considered to be one of the most seriously affected by climate change in the world. Hence, coastal wetlands are vulnerable. This study applied the Drivers - Pressures - State - Impacts - Responses approach to discuss and analyze the main challenges induced by climate change and its potential consequences for Xuan Thuy Ramsar site in the Red River delta, Vietnam. In this research we used both observed and predicted data on the impacts of climate change issued by the Ministry of Natural Resources and Environment, Vietnam, including changes in temperature and rainfall, and sea level rise. The results illustrated numerous potential impacts and pressures associated with climate change on the study site. Understanding the effect of these potential impacts on wetland ecosystems is very important for managers and policy-makers because current conservation programs in Xuan Thuy Ramsar site have not included climate change issues. In addition, the complexity of synthesis impacts associated with global climate change is also a big challenge for local stakeholders. Our review suggests that a long-term conservation planning to response to climate change is crucial rule towards sustainable management of Xuan Thuy Ramsar site.