Meeting of the SIL Plankton Ecology Group (PEG 2012) February 12-18, 2012, Mexico City, Mexico Book of Abstracts Book of Abstracts The Organizing Committee Brian Moss (UK) H.J. Dumont (Belgium) L. DeSenerpont Domis (The Netherlands) Miquel Lürling (The Netherlands) R.D. Gulati (The Netherlands) S. Nandini (Mexico) S.S.S. Sarma (Mexico) Z.M. Gliwicz (Poland) Abstracts of Presentations Invited talks, oral and poster presentations Abstracts of the SIL Plankton Ecology Group. Mexico City, Mexico,12-18 February, 2012 _________________________________________________________ Relation between microcystin-LR concentration and the potentially toxic cyanobateria in Valle de Bravo reservoir, Mexico State Alillo-Sánchez José Luis, Gaytán-Herrera Martha Leticia, Martínez- Almeida Victor Manuel and Ramírez-García Pedro Research and Postgraduate Division (UIICSE-CyMA Project), Universidad Nacional Autónoma de Mexico/FES-Iztacala, Avenida de los Barrios No. 1, 54090 Tlalnepantla, Estado de México, Mexico. [email protected] or [email protected] The presence of cyanobacterial blooms is a characteristic of eutrophic inland waterbodies. Some taxa produce toxins that are released to the environment. These include the so-called microcystins, which have hepatotoxic and dermatological effects on animals and humans. Valle de Bravo reservoir (Mexico State) is the main source of water for the Cutzamala system, which supplies drinking water to the west of Mexico City and conurbation areas of Mexico State. Monthly surface water samples were analyzed for physico- chemical parameters and cyanobacteria species richness and abundance at five stations from February to November 2010. We also measured the concentration of microcystin-LR using a commercial kit (EnviroLogixTM) based on ELISA assay. The results indicate the eutrophic condition of the reservoir. Of the 19 taxa of cyanobacteria found, Pseudanabaena wesenbergii and Microcystis mucicola, were the most frequent and abundant species. From February to June microcystin concentration exceeded the maximum guide value for drinking water sources established by WHO (1ȝg / L). The highest value (5.56 μg / L) was recorded in April. The concentration of microcystin was related with the biovolume reached by species of order Nostocales, especially Anabaena planctonica (r = 0.901, n=50). We suggest continuous monitoring of water quality in this reservoir and to alert users who practice the various recreational activities. 1 Abstracts of the SIL Plankton Ecology Group. Mexico City, Mexico,12-18 February, 2012 _________________________________________________________ Vertical flux of phytoplankton in a tropical, oligotrophic Mexican Lake Ardiles Vilma1, Alcocer Javier2 and Oseguera Luis A.2 1Programa de Posgrado en Ciencias del Mar y Limnología, UNAM..A.P, 70-305. Colonia Universidad Nacional Autónoma de México. 04510. Delegación Coyoacán. México, D.F. e-mail: [email protected] 2Facultad de Estudios Superiores Iztacala, UNAM. Proyecto de Investigación en Limnología Tropical. Av. de los Barrios No.1, Los Reyes Iztacala, Tlalnepantla, Estado de México 54090 México. Alchichica is a tropical, oligotrophic lake whose phytoplankton biomass is dominated by large size phytoplankton (i.e., diatoms and cyanobacteria). The fast sinking phytoplankton leads to carbon and other nutrient exportation out of the productive zone of the lake. The aim of the present study was to identify and measure the sedimentation fluxes of the phytoplankton species and their temporal dynamics along three years (June 2006 to June 2009) to better understand the magnitude of nutrient fluxes associated to the different dominant taxa. The phytoplankton fluxes were highest at the onset of the stratification, just after the winter diatom bloom. Phytoplankton fluxes varied between 8.5 x 106 and 1,159 x 106 cells m-2 d-1 during the circulation period and between 2.0 x 106 and 1,878 x 106 cells m-2 d-1 along the stratification. The main settling phytoplankton groups were diatoms, cyanobacteria and chlorophytes. From June 2006 to December 2008 the diatom Cyclotella alchichicana was the most important species found in the traps constituting up to 98%. However, from January to June 2009, Cyclotella choctawhatcheeana (33-70%) and Chaetoceros elmorei (0-57%) replaced C. alchichicana as the dominant species. Key words: phytoplankton flux, tropical lake, oligotrophic lake 2 Abstracts of the SIL Plankton Ecology Group. Mexico City, Mexico,12-18 February, 2012 _________________________________________________________ The physical and chemical behavior and phytoplankton biomass of an artificial aquatic system in Cozumel, Mexico Arroyo Castro Jovana, Cervantes Martínez Adrian and Medina Palomo Carolina Universidad de Quintana Roo, Unidad Académica Cozumel, Depto. Ciencias y Humanidades; Cozumel, Quintana Roo, 77600. [email protected] The following study describes the physical, chemical variables and the dynamics phytoplankton biomass (chlorophyll a) in an artificial aquatic system located in Cozumel, Mexico (N 20Û 29 '18.3" W 86° 56' 22.8"). This study considers two climatic periods (the rainy and winter storm season). Based on the physical and chemical analysis of the water, the system exhibited the following characteristics: warm tropical water (24.8± 1.9°C), low conductivity (389.6 ± 75.84PS/cm), freshwater (salinity= 0.2 ± 0 mg/l), poorly oxygenated (1.1 ± 0.3 mg/l) and saturated (7.7 ± 2.7%). Based on the biomass of phytoplankton the system can be classified as mesotrophic (5.2 ± 3.8mg/m3). It is important to mention that the concentration of the phytoplankton increased as the cold season neared, due to the probable decrease in the abundance of possible primary consumers that live in this system. Investigations of artificial systems allow us to understand the relationship between the phytoplankton biomass and dynamics, and physical and chemical behaviors of aquatic systems. Keywords: Biomass, Limnology, mesotrophy 3 Abstracts of the SIL Plankton Ecology Group. Mexico City, Mexico,12-18 February, 2012 _________________________________________________________ The light-dark bottle method: an option for the study of oxygen consumption of zooplankton in situ Benítez-Díaz Mirón Marcela Ivonne, Garza-Mouriño Gabriela and Castellanos-Páez María Elena Laboratorio de Rotiferología y Biología Molecular de Plancton. Universidad Autónoma Metropolitana. Calzada del Hueso 1100. Colonia Villa Quietud, Delegación Coyoacán. México, D. F. C.P. 04960. [email protected] There are various studies that explain the behavior of rotifers in low dissolved oxygen concentration; however, the knowledge about their oxygen consumption in the natural environment is very scarce. The purpose of this study was to quantify the in situ oxygen consumption of the planktonic fraction <50ȝm and the zooplankton fraction between 50-220ȝm. Six incubations were performed monthly during 2011. They were done in triplicate in sterile transparent and amber glass bottles of 4-liter of capacity. The zooplankton was concentrated 20 times and was starved for 45 minutes in water pre-filtered through 0.22ȝm, and then the incubations of 40 minutes were done in water pre-filtered through 50ȝm. The final oxygen content was determined by the method of Winkler. The initial oxygen values observed ranged from 3.18 to -1 9.45 mg.O2.L . Our results show that the oxygen consumption of the zooplankton community of less than 50 μm was between 0.075 and 0.53 -1 mg.O2.L , while the larger community of 50ȝm consumed from 0.28 to 1.51 -1 -1 mg.O2.L . The lower density was 35.58 ind. mL and the higher density was 1900.00 ind.mL-1. Finally, in terms of fixed carbon was found that in the experimental conditions [20x], the zooplankton can fix from 196.76 to 1045.95 mgC.m-3.h-1. Key words: zooplankton, oxygen consumption, light and dark bottles method. 4 Abstracts of the SIL Plankton Ecology Group. Mexico City, Mexico,12-18 February, 2012 _________________________________________________________ Morphometric characterization of Staurastrum gracile Ralfs (Chlorophyta) from tropical reservoirs in Mexico Calderón Eva1 and Tavera Rosaluz2 1 Posgrado en Ciencias Biológicas, Facultad de Ciencias, UNAM. 2 Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, UNAM Apartado Postal 70-747 CU Coyoacán, México DF. Email: [email protected] Morphometry of Staurastrum gracile was studied using in situ samples and isolations in pure cultures, with material collected on the shallow shores of reservoirs of the State of Mexico (Valle de Bravo and Taxhimay). We have documented in natural conditions as well as in the artificial, pleomorphic limits of this species (morphological variability that is part of life cycle) and polymorphism (morphological variability associated with environmental conditions). The documentation refers to a comparison of characters compiled from the literature, observed in situ and observed experimentally by modifying various conditions of pH and nutrient concentrations, which are some of the factors that desmids respond with great sensitivity. The population variability analysis based on morphometric tools, has helped to address critically the morphological overlap between varieties of S. gracile and between it and other species of Staurastrum. Based on the results, we question the validity of Staurastrum gracile var. nanum and Staurastrum paradoxum and suggest that geographical variation in S. gracile in Mexico corresponds to ecotypes associated with environmental conditions. 5