Spatial distribution and intra-annual variability of water masses on the Eastern Gulf of Cadiz seabed

This paper presents the spatial distribution and intra-annual variability of seabed hydrography in the Eastern Gulf of Cadiz based on more than 10 years of near-bottom CTD observations. Well-defined water masses and a variety of mixing products are persistently sorted along three bathymetric areas occupying particular depth intervals: (i) inner shelf waters (<60 m depth), with strong coastal and atmospheric influence; (ii) low-salinity Eastern North Atlantic Central Waters (ENACW) related to the Gulf of Cadiz Current (GCC) along the central and outer shelf (between 100 and 250 m depth); and (iii) a range of salinity and temperature flavors associated with the dense Mediterranean Outflow Water (MOW) occupying the deeper grounds. All three are characterized by significant March– November hydrographic differences suggesting an intra-annual variability pattern. After summer heating and stratification of the water column, warm (17.8 °C) and saline (36.26) waters occupy the inner-shelf in November whereas cooler (14.6 °C) and less saline (36.17) waters occur in March as the combined result of the erosion of the seasonal thermocline and intensified continental runoff. Offshore, colder, more saline and hence denser MOW invades the upper slope in March diluting the easternmost tip of a saltier ENACW wedge and nudging its outer rim up onto the shelf. This narrows and constricts the GCC band in winter, while its bottom trace appears to broaden and stretch eastwards in November. More effective MOW-ENACW mixing west of the Strait of Gibraltar driven both by an elevated MOW and a less stratified ENACW could explain the winter salinification of most of the grounds deeper than 250 m.En prensa2,088

Abundance of Anchovy eggs by CUFES: Inter-annual fluctuations and spatial patterns.

Data on the abundance of Anchovy eggs in the Gulf of Cadiz as collected by CUFES are explored in the present work in relation to their spatial pattern and inter-annual fluctuations. These data were gathered in 12 summer surveys, both acoustic (ECOCADIZ series) and DEPM (BOCADEVA series) ones, since 2004 to date (no survey in 2012). A total of 1499 CUFES stations were sampled, which distributed from the strait of Gibraltar, in Spain, to Cape San Vicente, in Portugal (in 2010 to Cape Sta. Maria only). The sampling scheme consisted in a grid of 21 parallel transects, normal to the shoreline and inter-spaced 8 nm, with the samples being collected every 3 nm at a c.a. 600 l/min flow with a 335 μm mesh size net and at a sampling depth of 5 m from the surface. A continuous record of SST and SSS at 5 m (termosalinometer) was coupled to the CUFES sampling. The surveys were carried out in June, July or August depending on the year. Oceanographic variables such as temperature, salinity and chlorophyll, and even the bottom topography of the shelf as well, they all showed significantly different in two regions: to the East and West of the Cape S. Mª. The density of Anchovy eggs presents a high variability between stations showing a very patched distribution. The stations with most eggs are located to the East of Cape Sta. Mª. Egg abundance also showed a very high between-year variability, ranging from 2955 eggs in 2005 to 41941 eggs collected in 2014. Regarding the spatial pattern of egg distribution, the 84.9% of the total egg density (all the surveys pooled) was collected in the area east of the Cape Sta. Mª (37.4 % in 2016), and the 89.8 % of total egg density in stations bellow 100 m depth (47.9 % in 2016). What happened in 2016? The mean temperature registered in 2016 in the Western stratum (22.0ºC) was practically the same that the mean temperature registered from 2004 to 2015 in the Eastern stratum (21.7ºC). The analysis of the centers of gravity of the eggs densities vs longitude and depth show significant trends, but not for latitude, which indicate a displacement towards the West in 2016. However, no trends were found in the centers of gravity of the acoustic energy (NASC) as a proxy of adults. Is then the westward displacement of the spawning in 2016 caused by an advective transport (currents and/or winds) or by other causes? What will be the further effect on recruitment? It would be good to obtain a statistical model in order to explain how the different variables affect the abundance of eggs, including other variables like the wind, tide... The presence of deep canyons crossing the shelf in the East of Cape Sta. Mª indicates that distance to the coast would be a better variable than depth

INFORME CAMPAÑA ARSA 0309

Durante los días 4 al 16 de marzo de 2009 se ha llevado a cabo la campaña ARSA0309, de prospección con arte de arrastre de fondo permaneciendo los días 4 y 5 en puerto debido al mal tiempo. Al igual que en años anteriores, la zona prospectada ha correspondido a la zona de plataforma y talud continental de la parte española del Golfo de Cádiz (Subdivisión IXa Sur del ICES), comprendida entre el meridiano 7º 20’ W (frontera con Portugal), y el paralelo 36º N, entre las isóbatas de 15 y 800 metros, hasta el límite de la distancia de 6 millas a la costa. Dicha campaña se encuentra inmersa dentro del programa de recopilación de datos básicos de la Unión Europea y está considerada como prioridad 1. La campaña se realizó a bordo del B/O "Cornide de Saavedra", siendo el objetivo previsto la estimación de los índices de abundancia (número y biomasa), de las especies demersales de mayor interés pesquero, así como de la fauna asociada a ellas

Variation of growth performance of the striped venus clam Chamelea gallina (Mollusca: Bivalvia) (Linnaeus, 1758) in relation to environmental variables along the southern part of its geographic range

This study reports relative growth, shell length-age keys and growth performance indices (overall growth performance (OGP) and phi prime) for the striped venus Chamelea gallina from the Huelva coast in southwest (SW) Spain. The morphometric relationship shell height (SH)/shell length (SL) presented isometric growth whereas SL/shell width (SW) and SL/weight (W) displayed negative allometric growth. Shell length at age was estimated through length-frequency distribution (LF) and internal shell growth bands by acetate peel method (AP). C. gallina population consists mainly of three age classes with shell lengths around 13-15 mm for the first year, 25 mm for the second year and 30 mm for the third year. The OGP and phi prime values obtained in the present study are within the range of values for other C. gallina populations from the Gulf of Cádiz. Nevertheless, marked differences in growth performance were observed between populations from the Black Sea (lower growth performance) and from other locations along the southern distribution area of this species, which may be related to the low levels of temperature (SST), salinity (SSS) and chlorophyll-a (chl-a) concentration that exhibit large intra-annual fluctuations.En prensa0,371

Influence of an upwelling filament on the distribution of labile fraction of dissolved Zn, Cd and Pb off Cape São Vicente, SW Iberia

Versión del editor2,088

Distribution and transport of dissolved trace metals in the Gulf of Cádiz, Spain

Trabajo presentado en el XVIII Seminario Ibérico de Química Marina, celebrado en Alicante (España) de 20 al 22 de julio de 2016.The Gulf of Cadiz plays a key role in the exchange of biogeochemical fluxes between the Mediterranean Sea and the Atlantic Ocean through the Strait of Gibraltar. Oceanographers have carried out many investigations in the Gulf of Cádiz on water mass circulation and mass balance of nutrients and carbon. However, despite its importance in the global ocean functioning, studies on trace metals in the Gulf of Cádiz and Strait of Gibraltar waters are very scarce. Here we show the concentrations of dissolved trace metal composition (i.e. Ag, Cd, Co, Cu, Fe, Mo, Ni, Pb and Zn) in the Gulf of Cádiz and Mediterranean Sea surface waters as obtained from 5 oceanographic campaigns. Our results indicate that the Gulf of Cádiz surface water mass is receiving large amounts of trace metals transported by the different rivers that flow into the Gulf of Cádiz. Thus, dissolved trace metals in these waters were highly variable with the highest ranges measured for Co (0.06 – 3.1 nM), Fe (0.6 – 392 nM) and Pb (0.04 – 512 nM).This work was financed by the MICCIN grants MEGOCA (CTM2014-59244-C3-3-R).N