In oxygen-depleted zones of the open ocean, and in anoxic basins and fjords, denitrification (the bacterial reduction of nitrate to give N2) is recognized as the only significant process converting fixed nitrogen to gaseous N2. Primary production in the oceans is often limited by the availability of fixed nitrogen such as ammonium or nitrate, and nitrogen-removal processes consequently affect both ecosystem function and global biogeochemical cycles. It was recently discovered that the anaerobic oxidation of ammonium with nitrite--the 'anammox' reaction, performed by bacteria--was responsible for a significant fraction of N2 production in some marine sediments. Here we show that this reaction is also important in the anoxic waters of Golfo Dulce, a 200-m-deep coastal bay in Costa Rica, where it accounts for 19-35% of the total N2 formation in the water column. The water-column chemistry in Golfo Dulce is very similar to that in oxygen-depleted zones of the oceans--in which one-half to one-third of the global nitrogen removal is believed to occur. We therefore expect the anammox reaction to be a globally significant sink for oceanic nitrogen.

Se indagó, de septiembre del 2005 a noviembre del 2007, las propiedades oceanográficas físicas, químicas y biológicas (zooplancton) más relevantes del Golfo Dulce, Pacífico Sur de Costa Rica, y las tipologías meteorológicas de la zona, con el objetivo de analizarlas y hacerlas disponibles como referencia en el establecimiento de actividades adecuadas para su conservación, dado que es un ecosistema acuático único en Costa Rica. El patrón de circulación de las aguas en el Golfo Dulce es el típico de estuarios tipo fiordo, con una estratificación de flujo en la columna de agua. Las corrientes marinas superficiales alcanzaron velocidades cercanas a los 18cm/s en la región de entrada al Golfo, que disminuyeron al ampliarse el área del golfo donde las velocidades llegaron a alcanzar poco más de 5cm/s en el extremo noroeste, Rincón. Predominó el flujo superficial de este-oeste, mientras que en la zona de Puerto Jiménez la velocidad fue moderada de 5.4cm/s con dirección sur. Se detectaron velocidades mayores cercanas al umbral de la entrada del golfo (17.8cm/s) y en el fondo el ámbito fue de 2.0cm/s a 4.8cm/s. Se establecieron cinco sitios de muestreo denominados GD1, GD2, GD3, GD4 y GD5, que se visitaron en cinco ocasiones, excepto en GD5 que se visitó solo una vez. No se detectó la ausencia de oxígeno disuelto en las aguas profundas del Golfo (70m a los 140m), aunque las concentraciones fueron bajas (0.25mg/L a 1.10mg/L). La distribución de las concentraciones de los nutrimentos reflejó los patrones usuales para sistemas estuarinos a nivel horizontal, y a nivel vertical las concentraciones de fosfato y silicato fueron mayores al descender en la columna de agua, tanto en la estación lluviosa como en la seca. La descomposición de la materia orgánica fue evidente puesto que las concentraciones de nitrato fueron incrementándose en las aguas profundas. De los datos de concentración de nutrimentos, se deduce que el Golfo Dulce puede ser considerado como un cuerpo de agua que se mantiene en un estado de muy buena calidad ambiental. El grupo zooplánctico dominante fue el de los copédodos (44%-83.6%). Los vientos oeste ecuatoriales se detectaron en junio y fueron más intensos entre septiembre y octubre, lo que correspondió con promedios altos de altura de las olas. A su vez, los vientos alisios de diciembre a abril disminuyeron la energía del oleaje que entra al golfo y por lo tanto la altura promedio de las olas. El ciclo anual de la precipitación fue un patrón bimodal típico del Pacífico de América Central, con máximos en mayo y octubre, con la interrupción debida al veranillo o canícula, y un mínimo de precipitación ocurrió en febrero. Golfo Dulce es un ambiente único en todo el Pacífico Este Tropical, y aunque parezca mostrar condiciones ambientales saludables, está amenazado por muchas actividades humanas; ante todo urge el establecimiento de políticas de ordenamiento y planificación de las mismas, para proteger el ecosistema bajo los principios de uso sostenible.

The availability of baseline data on water parameters and primary productivity is essential in comparative studies aimed at identifying environmental trends, like eutrophication, in coastal embayments. In this context, the objetive of this work is to make accessible data, collected from 2000 to 2002, on 13 water parameters (Secchi depth, temperature, salinity, dissolved oxygen, oxygen saturation, suspended matter, chlorophyll-a, phaeopigments, phosphate, silicate, ammonium, nitrite and nitrate) their temporal and spatial distribution, and primary productivity at four coastal sites of Costa Rica. The multi-parameter survey was conducted based on surface (1 m deep) water samples collected at a total of 128 stations at three Pacific and one Caribbean embayments: a bay under the influence of upwelling (Culebra Bay), a tidal estuary (Gulf of Nicoya), a semi-enclosed small coastal bay bordered by mangroves (Golfito Bay), and a Caribbean bay and port (Moin Bay). Graphic distributions of stations from the four embayments and for the Gulf of Nicoya were obtained by Principal Component Analysis (PCA).PCA Gabriel biplots were used to illustrate the relative importance of each parameter on the separation of stations. The four embayments were separated by PCA based on the 13 parameters. The maximum values recorded were: Secchi depth: 12.6 m; salinity: 35 psu; temperature: 32.5 oC; oxygen: 11.4 mg/L; oxygen saturation: 188 %; suspended matter: 156.04 mg/L; chlorophyll-a: 16.21 mg/m3; phaeopigments: 6.37 mg/m3; phosphate: 9.53 µmol/L; silicate: 156.11 µmol/L; ammonium: 2.66 µmol/L; nitrite: 2.47 µmol/L; and nitrate: 4.59 µmol/L. Salinity and several nutrients varied seasonally (dry vs rainy) in the Gulf of Nicoya estuary. Estimates of net primary productivity (Winkler oxygen method) produced a maximum 2 206 g C/m2/year at Culebra Bay. The maximum net PP (g C/m2/year) at the other three embayments, were: 1 601 (Gulf of Nicoya), 1 371 (Golfito Bay), and 1 100 (Moín Bay). Net PP values showed high variability in space and time, and ranged from negative to those associated with oligotrophic, eutrophic, and hypertrophic waters. In the Gulf of Nicoya 60 % of the values of net PP exceeded the reference value (500 g C/m2/year) to separate eutrophic from hypertrophic conditions. Rev. Biol. Trop. 66(Suppl. 1): S211-S230. Epub 2018 April 01.

Abstract:The input of contaminants to coastal ecosystems is a global problem on the rise. Data on metal pollution from tropical sites is often lacking and pilot surveys are urgently needed to provide a general framework to estimate the relative impact of these and other pollutants. The objective of this study was to make accessible data on trace metals collected during pilot surveys (2000)(2001)(2002)(2003)(2004)(2005)(2006) at four coastal embayments of Costa Rica. Cu, Fe, Mn and Zn were analyzed by Flame Atomic Absorption Spectrometry (FAAS) and Al, Cd, Ni, Pb and Sn by Graphite Furnace Atomic Absorption Spectrometry (GFAAS). Concentrations of Fe, Pb, Zn, Mn, and Ni were determined by FAAS or GFAAS, in tissues of the rock snail Acanthais brevidentata, the infaunal bivalves Anadara tuberculosa and Tagelus affinis (from three Pacific sites: Culebra Bay, Gulf of Nicoya, and Golfito Bay) and in the clam Polymesoda arctata from the Caribbean coast (Moín Bay). In addition, Sn, Cd and Cu were evaluated in tissues of T. affinis. A group of specimens of T. affinis was depurated for 72 hours in filtered seawater from the collection site. Concentrations varied between and within sites and also between parts of the same The relatively high concentration of Pb was probably related to the use at the time of sampling of leaded fuel in small boat operations at the site, while no evident cause was found for the high Mn values. Depuration was partially effective in lowering the metal burden in T. affinis. Data gathered during the pilot survey were indicative of relatively clean conditions of Culebra Bay, while the other three sites have important concentrations of certain contaminants, including metals. In spite of the fact that this data was collected more than a decade ago, it remains as the most recent available on trace metals from coastal mollusks of Costa Rica. Rev. Biol. Trop. 63 (4): 1007-1019. Epub 2015 December 01.

The objectives of this report are to make accessible data on the abundances (1984-1987, 49dates) of sipunculans, brachiopods and hemichordates at 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 upper Gulf ofNicoya estuary (10oN-85oW), Pacific coast of Costa Rica. Core (17.7 cm2) samples were collected at thesand-mud flat, and quadrats (0.2 m2) at the sand flat. Trace metal (Fe, Mn, Ni, Cr, Cd, Zn, and Pb)analyses were performed by Atomic Absorption Spectrometry (AAS) in tissues of the infaunal depositfeeder sipunculan Sipunculus nudus (non-depurated vs depurated) and in tissues and shells of theinfaunal filter-feeder brachiopod, Glottidia audebarti. The flats contrast in their sand (65% vs 90%) andsilt+clay (31.5% vs 5.6%) contents. At the sand-mud flat the brachiopods were represented by 129individuals, the sipunculans by 13, and the hemichordates by 185. The total area sampled by cores was1.83 m2. Estimated densities for the dates when the maximum number of each group was found, were: 29,5.7, and 40 ind./m2, respectively. Abundances were higher during the rainy season of 1984. Trace metalconcentrations in S. nudus collected at the sand flat decreased for all metals (except Cd) when medianvalues of non-depurated vs depurated individuals were compared. Maximum concentrations in non-depurated specimens, were: Fe (22.5 mg/g. dw) > Mn (234.6 µg/g. dw) > Zn (144.0 µg/g. dw) > Cu(52.7µg/g. dw) > Ni (15.5 µg/g. dw) > Cr (10.8 µg/g. dw) > Pb (9.3 µg/g. dw) > Cd (1.64 µg/g. dw).Maximum concentrations in non-depurated G. audebarti, were: Fe (21.6 mg/g. dw-soft parts) > Mn (Nodata) > Zn (123.4 µg/g. dw- soft parts) > Cu (31.4 µg/g. dw-pedicles) > Ni (No data) > Pb (21.0 µg/g.dw-shells) > Cd (5.2 µg/g. dw-soft parts) > Cr (4.7 µg/g. dw-shells). Maximum concentrations insediments were: Fe (60.3 mg/g. dw) > Mn (549.3 µg/g. dw) > Zn (83.1 µg/g. dw) > Cu (36.2 µg/g. dw)> Cr (31.5 µg/g. dw) > Pb (21.1 µg/g. dw) > Ni (20.6 µg/g. dw) > Cd (1.1 µg/g. dw).Theseconcentrations were expected for a non-industrialized estuary like the Gulf of Nicoya. At the sand flat, atotal of 76 individuals of G. audebarti, 112 of G. albida, and 366 of S. nudus were collected in 2015, in atotal sampled area of 10.6 m2. Estimated mean densities for the three dates were: 7.1, 10.5, and 31 ind./m2, for G. audebarti, G. albida, and S. nudus, respectively. The spatial distribution of the three specieswas aggregated and the maximum numbers found in a quadrat (0.2 m2) were 11, 18 and 20, respectively.The size range of G. audebarti was from 9.0 mm to 38.0 mm, and from from 6.0 mm to 29.0 mm for G.albida. The weight range of S. nudus was from 0.10 g to 2.55 g. These ranges are within those found forthese species elsewhere. Densities of G. audebarti and G. albida were relatively low, while those of S.nudus were relatively high when compared with data reported in the literature. No acorn worms werefound in 2015. G. audebarti had a relatively stable abundance, while G. albida decresed at the end of therainy season of 2015. The abundance of S. nudus increased towards the end of the rainy season andheavier (more than 1.25 g) specimens were also collected at this time. A strong ENSO was fullydeveloped in 2015 leading to above normal average temperatures and less rainfall in the Pacific coast ofCosta Rica, but the impact of this warming event on the fauna is unknown.