Salinity change in the subtropical Atlantic : secular increase and teleconnections to the North Atlantic Oscillation

Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 32 (2005): L02603, doi:10.1029/2004GL021499.Recent studies comparing shipboard data between the 1950's and the 1990's have shown significant, heterogeneous adjustments of the temperature-salinity structure of the N. Atlantic Ocean. Here, we present proxy records of temperature and salinity from aragonite sclerosponge skeletons, extending existing records of the Salinity Maximum Waters (SMW) of the N. Atlantic back to 1890. These proxy records show secular temperature increases of 1.6–2.0°C, higher than published global averages, and salinity increases of 0.35–0.5 psu, smaller than short-term secular trends recently measured. Salinity reconstructions vary more significantly on the decadal scale, showing changes that are related to low-frequency variations of the North Atlantic Oscillation (NAO). On both secular and decadal time scales, the records indicate significant thermohaline changes in the SMW, either via forcing at the surface or increasing depths of density surfaces in the Bahamas.This project was supported by National Science Foundation grants 9819147 and 0136941 (to P.K.S) and 9876565 and 0134998 (to S.R.T)

A Reminiscence of the Nicaraguan Filibusters.

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Stable carbon isotopic composition of Mytilus edulis shells: relation to metabolism, salinity, d13CDIC and phytoplankton.

Abstract Bivalve shells can potentially record the carbon isotopic signature of dissolved inorganic carbon (d 13 C DIC ) in estuarine waters, thereby providing information about past estuarine biogeochemical cycles. However, the fluid from which these animals calcify is a 'pool' of metabolic CO 2 and external dissolved inorganic carbon (DIC). The incorporation of respired 13 Cdepleted carbon into the skeletons of aquatic invertebrates is well documented, and may affect the d 13 C record of the skeleton. Typically, less than 10% of the carbon in the skeleton is metabolic in origin, although higher amounts have been reported. If this small offset is more or less constant, large biogeochemical gradients in estuaries may be recorded in the d 13 C value of bivalve shells. In this study, it is assessed if the d 13 C values of Mytilus edulis shells can be used as a proxy of d 13 C DIC as well as providing an indication of salinity. First, the d 13 C values of respired CO 2 (d 13 C R ) were considered using the d 13 C values of soft tissues as a proxy for d 13 C R . Along the strong biogeochemical gradient of the Scheldt estuary (The NetherlandsBelgium), d 13 C R was linearly related to d 13 C DIC (r 2 = 0.87), which in turn was linearly related to salinity (r 2 = 0.94). The mussels were highly selective, assimilating most of their carbon from phytoplankton out of the total particulate organic carbon (POC) pool. However, on a seasonal basis, tissue d 13 C varied differently than d 13 C DIC and d 13 C POC , most likely due to lipid content of the tissue. All shells contained less than 10% metabolic carbon, but ranged from near zero to 10%, thus excluding the use of d 13 C in these shells as a robust d 13 C DIC or salinity proxy. As an example, an error in salinity of about 5 would have been made at one site. Nevertheless, large changes in d 13 C DIC (>2&) can be determined using M. edulis shell d 13 C

New sponge records (Porifera) from King George Island, Antarctica, including the description of Phorbas sp. nov.

Sponges are an important and abundant component of Antarctic marine ecosystems. They harbour a great diversity of species and play a key role in these fragile benthic communities. The aim of this study was to identify the sponges collected during the Peruvian scientific campaigns to Antarctica carried out in the austral summer of 2018 and 2019 (ANTAR XXV and ANTAR XXVI). Specimens were collected by van Veen grabbers and small dredges down to 215 m depth at Admiralty Bay, Maxwell Bay and the proximities of Bransfield Strait, along King George Island. Photographs and field notes were taken. After collection, the macroscopical features (colour, shape, surface characteristics and consistency) and the internal anatomy were assessed. Dissociated spicules and skeleton slides were prepared to characterise the shape and size of the spicules, and the type of skeleton organisation. Seven species, including four Demospongiae and three Hexactinellida, were identified. Mycale (Oxymycale) acerata Kirkpatrick, 1907 and Phorbas glaberrimus (Topsent, 1917) are new records for Mackellar Inlet (Admiralty Bay); Haliclona (Reniera) aff. altera (Topsent, 1901), Rossella antarctica Carter, 1872 and Rossella fibulata Schulze & Kirkpatrick, 1910 are firstly reported for Maxwell Bay; Rossella podagrosa Kirkpatrick, 1907 constitutes a new record for Maxwell Bay and Bransfield Strait; and Phorbas sp. nov. is new to science. Among the Antarctic species, Phorbas sp. nov. mostly resembles P. glaberrimus (Topsent, 1917) in spicule sizes (oxeas, acanthostyles and isochelae), but its morphology and skeleton organisation are different. Phorbas glaberrimus presents a massive shape and a choanosomal skeleton composed of multispicular fibres that end in a palisade at the ectosome; while, Phorbas sp. nov. has a ramose habit and a plumose choanosomal skeleton composed by spicules running towards a paratangential ectosomal skeleton. With this study, the number of sponge species recorded from King George Island raises to 36

Esponjas de la Isla Rey Jorge y cercanías, Islas Shetland del Sur, Antártida

Las esponjas son organismos abundantes y usualmente dominantes en las comunidades bentónicas antárticas, donde cumplen roles ecológicos importantes. En ese sentido, es relevante conocer las especies que habitan zonas pobremente inventariadas (Campos et al., 2007). El objetivo de este estudio fue identificar las esponjas colectadas durante la Expedición Peruana ANTAR XXV (2017-2018), obtenidas mediante dragados en la Ensenada Mackellar (62°03'54''S 58°27'01''O), Bahía Maxwell (62°11'26‘‘S 58°51'34‘‘O) y al extremo norte del Estrecho de Brandsfield (62°05'06‘‘S 58°40'31‘‘O), en el marco de colaboraciones interinstitucionales. Se analizó la morfología externa (forma, superficie, color, consistencia y características de los ósculos); además, se examinaron tanto la organización del esqueleto como la forma y medida de las espículas. Fueron identificadas siete especies, agrupadas en Demospongiae (n=4) y Hexactinellida (n=3). Entre las demosponjas, Mycale (Oxymycale) acerata, previamente registrada para las Islas Decepción y Livingston, y el Estrecho de Bransfield (Van Soest et al., 2019), se reporta por primera vez para la Ensenada Mackellar (-24 m). Phorbas glaberrimus, citada para el Estrecho de Bransfield y Pasaje Drake (Van Soest et al., 2019), constituye un registro nuevo para Bahía Maxwell (-141 m). Asimismo, las otras dos especies de demosponjas, Phorbas sp. y Haliclona sp., podrían representar nuevas ocurrencias para el área. Entre las hexactinélidas, fueron identificadas tres especies del género Rossella (Rossella sp. 1, 2 y 3), que se diferencian principalmente por los tipos de espículas hipodermales y la proyección de estas en la superficie. Estos nuevos registros serán añadidos a las bases de datos de diversidad antártica ya existentes, contribuyendo a la comprensión de los patrones de distribución de las esponjas de la Antártida

Aspects cinétiques, quantitatifs et ultrastructuraux de l'endocytose, la digestion et l'exocytose chez les éponges

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Aspects cinétiques, quantitatifs et ultrastructuraux de l'endocytose, la digestion et l'exocytose chez les éponges

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Micromorphology and ultrastructure of Caribbean sclerosponges - I. Ceratoporella nicholsoni and Stromatospongia norae (Ceratoporellidae: Porifera)

Fine structural analysis of living tissue of the sclerosponges Ceratoporella nicholsoni (Hickson) and Stromatospongia norae Hartman, collected near Discovery Bay, Jamaica, between 1984 and 1986, was carried out using transmission and scanning electron microscopy (TEM and SEM). The thick dermal membrane of these sponges is covered by exopinacocytes having a "T" shape in sections perpendicular to the surface. A dense, complex glycocalyx is produced at the surface of these cells. Choanocyte chambers are diplodal and unusually small. The inhalant and exhalant canals of both species are characterized by the presence of valvules, made by transverse lamellipodial processes of the endopinacocytes lining them. An abundant and diversified bacterial community occupies almost 20% of the mesohyl. A single layer of active basopinacocytes lines the mesohyl at the interface between the living tissue and the aragonitic skeleton. Basopinacocytes are presumed to be precursors of the irregular fibrillar organic matrix found in the aragonitic skeleton. Sclerocytes and spongocytes are abundant in the vicinity of the siliceous spicules. Typical lophocytes releasing smooth collagen fibrils are common in the dermal membrane as well as in the choanosome where they can be grouped in bundles. Uniquely, C. nicholsoni elaborates rough intercellular fibrils characterized by periodically spaced thickenings. The endolithic algae Ostreobium sp. is present in the most apical zones of the aragonitic skeleton, but does not seem to interfere with its development. The striking micromorphological resemblances between both species are discussed and compared to demosponges. © 1989 Springer-Verlag.SCOPUS: ar.jinfo:eu-repo/semantics/publishe