Revista de Biología Tropical Vol.64 (3)

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https://hdl.handle.net/10669/73124

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Changes in abundance and composition of a Caribbean coral reef zooplankton community after 25 years
(2016) Carrillo Baltodano, Allan Martin; Morales Ramírez, Álvaro
Coral reef zooplankton represents a key community in coral ecosystems, as they are involved in trophic and biogeochemical dynamics, and recruitment processes. Zooplankton abundance, composition and biomass were surveyed at six stations within the coral reef at Cahuita National Park, Limon, Costa Rica, in order to compare with the only previous study conducted during 1984. Samples were collected monthly (September 2010-August 2011). Seston biomass (0.49-85.87 mg/m3) and total abundance (1 145-112 422 ind./m3) fluctuated among the months and the stations. Higher values of these two variables were found in the rainiest months (November 2010 and May 2011). A total of 38 taxa were identified, of which calanoid copepods abundance dominated year round (66 %), followed by appendicularians (12 %). Zooplankton mean abundance in this survey resulted 20 times higher (13 184 ± 4 104 ind./m3)than in 1984 (645 ± 84 ind./m3). Copepods and appendicularians were the groups that differed the most, relative to the 1984 study, resulting in 63 and 170 times more abundant overall, respectively. An increase in terrestrial runoff and nutrient input during the past 30 years could explain these differences. High abundances of zooplankton may constitute an important food source for coral reef organisms in Cahuita ecosystem. In addition, zooplankton abundances here reported for Cahuita are among the worldwide highest coral reef zooplankton abundances, and further trophic models can help elucidate its role in coral reef resilience in the Caribbean Coast of Central America.
Brachiopods, sipunculans, enteropneusts and metals from two estuarine tidal flats, Pacific, Costa Rica
(2016-09) Vargas Zamora, José A.; Acuña González, Jenaro; Vásquez, Fiorella; Sibaja Cordero, Jeffrey Alejandro
Reports on the abundances and on metal concentrations in intertidal estuarine invertebrates from the Eastern Tropical Pacific are rare. Thus, the objectives of this report are to make accessible data on the abundances (1984-1987, 49 dates; 2013, 12 dates) of sipunculans, brachiopods and hemichordates from a sand-mud flat; and on trace metals (1996, 2000) and abundances (2015, 3 dates) of sipunculans and brachiopods at a sand flat in the Gulf of Nicoya estuary (10o N-85o W). Cores (17.7 cm2) were collected at the sand-mud flat, and quadrats (0.2 m2) at the sand flat. The flats contrasted in their sand (65 % vs 90 %) and silt+clay (31.5 % vs 5.6 %) contents. At the sand-mud flat (1984-87: 1.83 m2) the sipunculans were represented by 13 individuals, the brachiopods by 129 and the acorn worms by 185, with estimated maximum densities of: 5.7, 29, and 40 ind./m2, respectively. Trace metal (Fe, Mn, Ni, Cr, Cd, Zn, and Pb) analysis (Atomic Absorption Spectrometry) were conducted in specimens of Sipunculus nudus (Sipuncula) and Glottidia audebarti (Brachiopoda). Maximum mean concentrations in S. nudus were: For non-depurated worms, Fe (16.0 mg/g dw) > Mn (165 µg/g dw) > Zn (81 µg/g dw) > Cu (26 µg/g dw) > Cr (11 µg/g dw) > Ni (10.4 µg/g dw) > Pb (9.3 µg/g dw) > Cd (1.2 µg/g dw). For 72 hour depurated worms: Fe (5.0 mg/g dw) > Mn (61 µg/g dw) > Zn (39 µg/g dw) > Cu (24 µg/g dw) > Ni (8.4 µg/g dw) > Pb (2.7 µg/g dw) > Cd (0.62 µg/g dw). For G. audebarti: Fe (1.6 mg/g dw-soft parts) > Zn (123.5 µg/g dw-soft parts) > Cu (31.4 µg/g dw-pedicles) > Pb (21.0 µg/g dw-shells) > Cd (5.2 µg/g dw-soft parts) > Cr (4.7 µg/g dw-shells). For sediments; Fe (46 mg/g dw) > Mn (41.3 µg/g dw) > Zn (63 µg/g dw) > Cu (36.2 µg/g dw) > Cr (31.5 µg/g dw) > Pb (21.1 µg/g dw) > Ni (16.1 µg/g dw) > Cd (1.1 µg/g dw). These concentrations were expected for a nonindustrialized estuary. At the sand flat (Area sampled: 10.6 m2 ) 76 individuals of G. audebarti, 112 of G. albida, and 366 of S. nudus were collected in 2015, with estimated maximum densities of: 7.1, 10.5, and 31 ind./m2, respectively. Densities of G. audebarti and G. albida were relatively low, while those of S. nudus were relatively high when compared with other reports. The shell lenght of G. audebarti ranged from 9.0 mm to 38.0 mm and from 6.0 mm to 29.0 mm for G. albida. These ranges were within those found for these lingulides elsewhere. The mean length of S. nudus was 41 mm and the maximum weight was 1.6 g, which are small. No brachiopods were found at the sand-mud flat in 2013, nor enteropneusts at the sand flat in 2015. G. audebarti had a relatively stable presence, while G. albida almost vanished from the samples at the end of 2015. The spatial distributions of the three invertebrates were found aggregated at both intertidal flats. Strong ENSO warming events during 1983 and 2015, and red tides in 1985 may have influenced the abundances.
Micromorfología de los foliolos de pejibaye Bactris gasipaes (Arecaceae) var. Diamantes-10
(2016-09) Sánchez Chacón, Ethel; Alvarado Rodríguez, Olman; Rodríguez Arrieta, Jesús Alexander; Gómez Alpízar, Luis
Bactris gasipaes se cultiva ampliamente para el aprovechamiento del palmito y el consumo de los frutos. En este trabajo se realizó una descripción de las características micro morfológicas de los foliolos de plantas adultas de la variedad sin espinas Diamantes-10 de B. gasipaes, recolectadas en la Estación Experimental Diamantes en Guápiles, Costa Rica. Se utilizó microscopía de luz, electrónica de barrido y de transmisión. Para el estudio se recolectaron 25 foliolos y se evidenció abundante cera epicuticular en la superficie adaxial y abaxial. La epidermis está compuesta de células isodiamétricas y las células de la hipodermis tienen forma rectangular y son de mayor tamaño que las de la epidermis, también se observaron células buliformes. Los foliolos son anfiestomáticos en las áreas intercostales y alternan con bandas de células epidérmicas. El mayor número de estomas se encuentra en la superficie abaxial. Estos foliolos presentan tres tipos de tricomas. El parénquima presenta varios estratos no muy bien definidos con presencia de astroesclereidas. También se observan haces de fibras entre el parénquima que forman grupos de células muy compactas. La vena central presenta varios haces vasculares, algunos dispuestos de forma continua y todos ellos se encuentran rodeados de una vaina de tejido esclerotizado, algunas de estas fibras presentaron protoplastos vivos. Todas las venas menores presentan la misma anatomía de los haces vasculares de la vena central. Los vasos del protoxilema y metaxilema tienen paredes laterales con ornamentaciones escalariformes. El floema se ubica hacia la superficie adaxial de la vena y en el corte se observaron las células cribosas y células compañeras rodeadas de células de parénquima y fibras. Las células compañeras presentaron plasmodesmatas ramificados unidos a un elemento criboso y en ellos se evidenció cuerpos de proteína, llamada proteína-P. La diferencia principal en la anatomía de los foliolos de la var. Diamantes-10 radica en la ausencia de espinas, pero en el resto de la morfología no parece presentar cambios morfológicos con el resto de las variedades de B. gasipaes K.

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