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

Spatio-temporal variability of mid-size pelagic fishes in the Gulf of Cadiz shelf waters in relation to climatic and environmental drivers

Understanding spatio-temporal distribution patterns of mid-size pelagic fish species (MSPF) is of great interest from the standpoint of both their management and conservation. MSPF inhabiting in the Gulf of Cadiz (SW Iberian Peninsula, Atlantic Ocean) are relevant because they contribute to a large number of individuals captured by the different fishing métiers operating in the area. So far, information on their spatial distribution and temporal changes remain scarce in the study area despite their implications in their stock discrimination and management. Herein, temporal changes of the distribution patterns of abundance and their response to environmental drivers of five MSPF (Scomber colias, Scomber scombrus, Trachurus trachurus, Trachurus mediterraneus and Trachurus picturatus) off the Gulf of Cadiz (GoC) are analyzed from acoustic surveys data for the period 2007-2017. In particular, we evaluated intra- and inter-specific overlapping over time and space using four spatial indices. The species’ abundance and distribution were estimated and mapped by applying geostatistical techniques taking into account autocorrelation between observations. Furthermore, analyses including environmental variables were tested to explain such spatial fluctuations. The main findings showed a progressive reduction of their distribution area in all species over time except for T. trachurus. The only species overlapping in space and time wasbetween T. picturatus and S. colias. The distribution areas of S. colias and T. mediterraneus were notably reduced and showed northern/southern preferences over the years. The main environmental variables shaping the abundance and distribution of each species were found to be chlorophyll and temperature. Climatic indices such as NAO and AMO affected MSPF by reducing or increasing their spatial distribution. Finally, we discuss implications of our findings to contribute to the implementation of the Marine Strategy Framework Directive in the frame of implementing an effective ecosystem approach to fisheries management in the region

BOCADEVA 0714 Gulf of Cadiz Anchovy Egg Survey and 2014 SSB preliminary estimates

This working document provides a brief description of the survey, laboratory analysis and estimation procedures used to obtain the Gulf of Cadiz anchovy SSB by DEPM for 2014 in the South-Atlantic Iberian Stock. Results are preliminary, because the estimation of the spawning fraction is not available yet

Spatial distribution and estuarine sources of dissolved organic matter export to the coastal zone 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.Dissolved organic matter (DOM) is a major component of the organic matter transported to the coastal zone by rivers. It controls ecosystem-level processes (e.g. food web) and constitutes an important pathway for nutrients transport from land to coastal waters. We know that estuarine discharges affect the primary production and nutrient composition in the adjacent coastal area. For instance, the current hypernutrification of the Guadalquivir estuary may benefit primary production on adjacent coasts. However, studies on DOM in the Gulf of Cádiz waters are unknown despite its importance in the global ocean functioning. The Gulf of Cádiz is under the estuarine influence of three main estuaries: Guadiana, Tinto-Odiel and Guadalquivir. The present study evaluates the relevance of DOM and the estuarine influence and environmental factors which determine its distribution in the Gulf of Cádiz. Our results suggest that the Gulf of Cádiz water mass is receiving large amounts of dissolved organic transported by the Guadiana and Guadalquivir rivers and much lesser from Tinto-Odiel. Thus, the estuarine influenced area explained the fDOM variability in the Gulf of Cadiz and this variability was shaped by turbidity, water depth and distance from the coast. Within the estuarine ecosystems, salinity and turbidity were the main factors explaining the fDOM variability.This work was financed by the MICCIN grants DILEMA (CTM2014-59244-C3-2-R).N

Anchovy Spawning Stock Biomass of the Gulf of Cadiz in 2020 by the DEPM

The Daily Egg Production Method (DEPM) to estimate the Anchovy Spawning Stock Biomass (SSB) in the Gulf of Cádiz (ICES, Subdivision 9a South) is conducted by Spain (Centro Nacional Instituto Español de Oceanografía, CSIC) every three years, since 2005. BOCADEVA 0720 is the sixth survey of the historical DEPM series for anchovy in the Gulf of Cádiz and was delivered on board R/V Ramón Margalef (CNIEO) from the 9th to the 17th of July 2020. The surveyed area extended from Strait of Gibraltar to Cape San Vicente (Spanish and Portuguese waters in the Gulf of Cadiz). Plankton samples, along a grid of 21 transects perpendicular to the coast were obtained for the spawning area delimitation and density estimation of the daily egg production. The survey objectives also included the characterization of the oceanographic and meteorological conditions in the study area. The samples to estimate adult parameters (sex ratio, female mean weight, batch fecundity and spawning fraction) were obtained in the acoustic survey “ECOCADIZ 2020-07”, carried out during the same period. This working document provides a d escription of the survey, laboratory analysis and estimation procedures used to obtain the Gulf of Cadiz Anchovy SSB by DEPM for 2020 in the South-Atlantic Iberian Stock

BOCADEVA 0720. Anchovy DEPM survey in the Gulf of Cadiz

The Daily Egg Production Method (DEPM) to estimate the Anchovy Spawning Stock Biomass (SSB) in the Gulf of Cádiz (ICES, Subdivision 9.a South) is conducted by Spain (Instituto Español de Oceanografía, IEO) every three years, since 2005. BOCADEVA 0720 is the sixth survey of the historical DEPM series for anchovy in the Gulf of Cádiz and was delivered on board R/V Ramón Margalef (IEO) from the 9th to the 17th of July 2020.This working document provides a brief description of the survey and the progress status of t h e laboratory analysis c a r ri e d o u t to obtain the Anchovy SSB by the a ppl i c at i o n o f th e DEPM in the South-Atlantic Iberian Stock

Observación de oportunidad de un Giro argelino al sur de Cabo de Palos (Mediterráneo sudoccidental)

Large anticyclonic eddies can detach from the Algerian Current, forming open-sea Algerian Eddies. These mesoscale structures have been intensively studied by means of sea surface temperature and altimetry data, and using numerical models. However, few studies describe an in situ sampling of their whole vertical structure. Furthermore, the area extending from Cape La Nao (western edge of the Balearic Channels) to the Almería-Orán Front has received very little attention, and it could be considered that there is a gap in our present oceanographic knowledge of this part of the western Mediterranean. An Algerian Eddy lasting for several months was detected in December 2021 to the south of Cape Palos. In order to analyse this eddy, an opportunity sampling was designed taking advantage of the periodic monitoring campaign RADMED 0222. This sampling revealed that the eddy had a baroclinic character, affecting the whole water column. These results suggest that this eddy was generated at the Algerian Current, finally affecting an area close to the eastern Spanish coast. The presence of these structures in this region of the western Mediterranean could alter the southward progression of the Northern Current and even the presence and structure of the Almería-Orán Front.Giros anticiclónicos de gran tamaño pueden desprenderse de la Corriente Argelina, llegando a formar giros en mar abierto. Estas estructuras de mesoescala han sido estudiadas intensamente mediante datos de temperatura superficial del mar, datos de altimetría, y modelos numéricos. Sin embargo, hay pocos trabajos que describan mediante medidas in situ la estructura vertical de estos giros. Al margen de esta circunstancia, la zona que se extiende desde el Cabo La Nao (en el extremo occidental de los Canales Baleares) hasta el Frente Almería-Orán, ha recibido poca atención, pudiéndose considerar que existe una laguna en nuestro conocimiento sobre la oceanografía de esta zona. Un giro anticiclónico fue detectado en diciembre de 2021 al sur de Cabo de Palos, pudiéndose observar durante varios meses. Para analizar este giro se diseñó un muestreo de oportunidad, aprovechando la campaña rutinaria RADMED0222. Este muestreo mostró la estructura baroclina del giro, la cual afectaba a toda su extensión vertical. Los resultados obtenidos también sugieren que el giro se formó en la Corriente Argelina, afectando finalmente a una zona próxima a la costa española. La presencia de este tipo de estructuras en esta región del Mediterráneo Occidental podría afectar a la progresión hacia el sur de la Corriente Septentrional, e incluso a la presencia y estructura del Frente Almería-Orán