Southern Spanish Coast Research Articles

A method to establish marine bio-regions in the pelagic ecosystem based on phytoplanktonic communities. Aplication to the southern Spanish coast

Bioregions in the pelagic ecosystem are frequently established on the basis of remotely sensed properties of the sea surface, such as sea surface temperature or sea surface chlorophyll concentration. Those works dealing with the regionalization of the marine ecosystem by means of the use of properties of the water column are less frequent, and even less those that obtain the data from periodic in situ monitoring programs, which are scarce. In this work we use time series of micro, nano and pico-phytoplanktonic abundances in the upper 100 m of the continental shelves of the Gulf of Cadiz and the Alboran Sea from the projects STOCA and RADMED (southern coast of Spain, Western Mediterranean). The use of times series allows us to estimate the median phytoplanktonic abundances of several phytoplanktonic groups along the water column. These statistics differ substantially from those abundances obtained for one particular campaign, reflecting the large seasonal and inter-annual variability of phytoplanktonic communities. These median profiles, estimated for the four seasons of the year and for several phytoplanktonic groups characterize each of the locations sampled in the aforementioned monitoring programs and are used for establishing the similarity between them. Then, these locations are grouped using a cluster analysis. Using some simulations from numerical experiments we determine which metrics and methods of analysis are the more suitable ones for the regionalization of the area of study. A bootstrap method is also used to determine which differences among bioregions can be considered as statistically significant. Despite the existence of a fast current that connects the Gulf of Cadiz and the Alboran Sea, our results show that the outer part of the Gulf of Cadiz shelf, and that of the Alboran Sea, can be considered as two differentiated bioregions. The latter region shows a higher productivity with a higher abundance of large cells such as diatoms, and the dominance of Synechococcus bacteria over Prochlorococcus ones.

Fish resource exploitation in the southern Atlantic coast of the Iberian Peninsula: A view from the traceological analysis of flaked stone tools (sixth-fourth mill. cal BCE)

In this paper, we provide new data on fish resource exploitation during the Mesolithic and Neolithic period on the Atlantic coast of the Iberian Peninsula. Evidence from four different sites is presented: Vale Marim I (end of the seventh/beginning of the sixth millennium cal BCE) and Vale Pincel I (2nd and 3rd quarters of the sixth millennium cal BCE), both located on the southwestern Portuguese coast, and La Esparragosa and SET Parralejos (fourth-third millennia cal BCE), both located on the southern Spanish coast. The analysis of the lithic assemblages by means of use-wear analysis provided evidence of fish-processing activities. The analysis of the archaeological tools has been based on a renewed experimental framework for fish-related use-wear traces. Despite data being still scarce and fragmentary, this study points out the necessity of a more integrating approach, including traceological analysis in the framework of a broader research on prehistoric fishing.

Monitoring continuous subsidence in the Costa del Sol (Málaga province, southern Spanish coast) using ERS-1/2, Envisat, and Sentinel-1A/B SAR interferometry

In this paper we analyze the subsidence behavior of a coastal area in the province of Málaga (Costa del Sol), southern Spain, in the period 1992-2018 using C-band SAR interferometry. The area comprises several zones of interest where continuous deformation has happened during the analyzed period. Using SAR data from ESA’s ERS-1/2, Envisat, and Sentinel-1A/B satellites, and Multi-Temporal InSAR methods we detect and monitor subsidence in highly populated and industrial areas, airport, harbor, as well as local instabilities over a railway line and a highway. In a previous work, we reported a subsidence due to intensive use of groundwater in some populated towns in the period 1992-2009 with maximum line-of-sight (LOS) rates of the order of –11 mm/yr. In this contribution, we confirm the subsidence trend. Furthermore, we detect an increase in the deformation rates for the most recent period (2014-2018), suggesting that the overexploitation of the aquifers has not ceased.

Environmental quality in sediments of Cadiz and Algeciras Bays based on a weight of evidence approach (southern Spanish coast)

This research applies an integrated sediment quality assessment method using a weight of evidence approach to Cadiz and Algeciras Bays (southern Spain). The method is composed of several analyses (particle size profile, aqua regia extractable metals, acid labile metals, total organic carbon, toxicity bioassay with Photobacterium phosphoreum and macrobenthic community alteration).The proposed method provides a single result, the environmental degradation index (EDI). EDI defined samples as low degraded (outer areas of both bays) and moderately degraded (Inner Bay of Cadiz Bay, the surroundings of Algeciras port and the northern part of Algeciras Bay). These samples showed the highest concentration of aqua regia extractable metals, which exceeded effects range-low (ERL) for Zn (51–176mg/l), Cu (11–54mg/l), As (4.3–9.5mg/l), Hg (0.17–0.28mg/l), Ni (23–82mg/l), and. Cr (37–134mg/l). They also exceeded some quality criteria for total organic carbon (4.0–6.5%) and toxicity (120–240TU/g) and showed poor results for macrobenthic community.

Micromorphology of hydromorphic soils developed in fluvio-marine sediments during the Middle-Late Pleistocene transit in the Gulf of Cadiz (Atlantic South Spain) .

This study establishes the controlling factors in the soil development in the ancient coastal plain of the Guadalquivir River along the southern Spanish coast (Huelva) shortly before 100 ka BP. The macro and micromorphological study indicates that a sedimentation hiatus allowed soil formation (extensive clay illuviation) together with the development of widespread redoximorphic features linked to iron oxide depletion and accumulation. Groundwater fluctuations driven by the overall sea-level rise during the onset of the last interglacial period triggered the pervasive occurrence of redox processes, probably acting in the coastal zone from the whole Middle Pleistocene as witnessed in inland outcrops. The resulting redoximorphic pedofeatures show a differential development in the studied zone, which is linked mainly to the activity of the Torre del Loro Fault leading regional differential upwarping of the ancient coastal area as well as local water-escape processes in the fault zone. Petrological, mineralogical and micromorphological data strongly suggest that the occurrence of multiple inheritances of iron-rich pedofeatures from previous Plio-Pleistocene weathering profiles developed under warmer and humid climatic conditions. Several pedofeatures (corroded quartz grains and runiquartz) do not correspond to the temperate oceanic climate prevailing in the zone during soil formation, and are reworked from former stronger weathering conditions. They are included in strongly iron-impregnated opaque domains that can be interpreted as inherited iron-rich nodules or clasts already present in the host sediments. These iron-rich pedofeatures have been subject to subsequent iron mobilization giving place to the iron depletion and accumulation domains observed in the micromorphological scale. Differential iron bleaching is not always linked to the fissure and/or pore-system present in the groundmass, suggesting the occurrence of differential water and sediment vertical fluxes (micro water-escape features) within the soil enhance the redoximorphic features around the fault zone.

Loggerhead Strandings and Captures Along the Southern Spanish Coast: Body Size–Based Differences in Natural Versus Anthropogenic Injury

Abstract Human and natural factors threaten loggerhead turtle (Caretta caretta, Linnaeus 1758) survival in the western Mediterranean basin. Loggerhead stranding data in the south of Spain provide evidence that human activities are having a more detrimental effect on larger-sized loggerhead turtles. The straight carapace length of 162 individuals affected by natural causes averaged 35.15 cm; whereas, that of 179 individuals affected by human-related causes averaged 46.23 cm. The difference was highly significant.

14C-Dated Charcoal and Sediment Drilling Cores as First Evidence of Holocene Tsunamis at the Southern Spanish Coast

At 2 locations of the southern Spanish coast, we found indications for tsunamis induced by submarine earthquakes. Charcoal, which we sampled in 2 stratified, assumed tsunamigenic sediment (tsunamites) layers at the shore outside the ruins of the Roman city of Baelo Claudia, close to the Strait of Gibraltar (province of Cádiz), and radiocarbon dated, surprisingly turned out to be of identical age, about 465 BP. In the laguna of the Cabo de Gata (province of Almería), we found possible remnants of tsunamites in drilling cores deposited above organic sediments, 14C dated as 680 ± 30 BP.

Release rates for control of Bemisia tabaci (Homoptera: Aleyrodidae) biotype “Q” with Eretmocerus mundus (Hymenoptera: Aphelinidae) in greenhouse tomato and pepper

Abstract Tomato and sweet pepper are the principal crops grown in protected culture on the southern coast of Spain. Augmentative biological control based on the parasitoid Eretmocerus mundus Mercet promises to be a useful component to manage Bemisia tabaci , the key pest of these and other horticultural crops. The present studies were undertaken with the objective of evaluating control obtained with different release rates under simulated commercial conditions. Experiments were conducted in an air-conditioned plastic greenhouse located on the southern Spanish coast during the two main horticultural cropping seasons of the region (fall-winter and spring). Host plant (tomato and sweet pepper) constituted the main plots and release rate of E. mundus (0, 1.5 and 6 m −2 ) the subplots in split plot design with four replicates. No other management practices were used against whitefly. Whitefly populations in fall reached over 80 nymphs/100 cm 2 leaf surface in pepper and twice this in tomato. Nevertheless, control using the high release rate in fall exceeded 90% in both crops, with no differences between rates in pepper, although the high rate was significantly better in tomato. Whitefly populations on pepper in spring reached densities five times greater than in fall, and yet control equalled or exceeded 95% with the high rate. Adult whiteflies on tomato were reduced by 92% in response to the high rate in spring, but nymphs were only reduced 69%. These experiments suggested that, although higher rates may be required in tomato to achieve the same level of control as in pepper, good suppression of B. tabaci could be achieved in both crops under most conditions using E. mundus without recourse to insecticides.

Particle fluxes in the Almeria-Oran Front: control by coastal upwelling and sea surface circulation

Particle flux data were obtained from one instrumented array moored under the direct influence of the Almeria-Oran Front (AOF) in the Eastern Alboran Sea, Western Mediterranean Sea, within the frame of the “Mediterranean Targeted Project II-MAss Transfer and Ecosystem Response” (MTPII-MATER) EU-funded research project. The mooring line was deployed from July 1997 to May 1998, and was equipped with three sequential sampling sediment trap-current meter pairs at 645, 1170 and 2210 m (30 m above the seafloor). The settling material was analysed to obtain total mass, organic carbon, opal, calcium carbonate and lithogenic fluxes. Qualitative analyses of SST and SeaWiFS images allowed monitoring the location and development of the Western and Eastern Alboran Sea gyres and associated frontal systems to determine their influence on particle fluxes. Particle flux time series obtained at the three depths showed a downward decrease of the time-weighed total mass flux annual means, thus illustrating the role of pelagic particle settling. The total mass flux was dominated by the lithogenic fraction followed by calcium carbonate, opal and organic carbon. The time series at the various depths were rather similar, with two strong synchronous biogenic peaks (up to 98 mg m −2 day −1 of organic carbon and 156 mg m −2 day −1 of opal) recorded in July 1997 and May 1998. Through comparing the fluctuations of the lithogenic and calcium carbonate-rich fluxes with the biogenic flux, we observed that the non-biogenic fluxes remained roughly constant, while the biogenic flux responded strongly to seasonal variations throughout the water column. Overall, the temporal variability of particle fluxes appeared to be linked to the evolution of several tens of kilometres in length sea surface hydrological structures and circulation of the Alboran Sea. Periodic southeastward advective displacements of waters from upwelling events off the southern Spanish coast were observed on SST and SeaWiFS images. In between these periods, widespread phytoplankton blooms were observed. The influence of the varying surface structures resulted in changes in the biogenic particle flux. For example, we observed an opal pulse in April 1998 that resulted from a diatom-rich highly productive frontal surface situation above the mooring line. Estimation of the annual organic carbon export and calculation of a seasonality index indicate that the overall dynamics of the carbon reservoir within the Eastern Alboran Sea appears to be strongly influenced by the sea surface hydrological structures.

The Recycled Orogenic Sand Provenance from an Uplifted Thrust Belt, Betic Cordillera, Southern Spain

The Betic Cordillera of southern Spain represents an uplifted foreland fold–thrust belt. Source rock types of the Betic Cordillera include metamorphic (mainly phyllite, schist, quartzite, and gneiss), sedimentary (siliciclastic and carbonate), volcanic (felsic to intermediate pyroclasts), and mantle-derived (peridotite, gabbro, serpentinite, and serpentine schist) rocks. The fluvial systems range that transect the Betic Cordillera are the major detrital source of sediment along the southern Spanish coast, supplying sand to beaches and offshore depositional systems in the Alboran Sea basin. Three key sand petrofacies derived from the Betic mountain belt reflect the main clastic contribution of known source rocks. All the sands are quartzolithic, ranging from quartz-rich to lithic-rich. Fluvial systems draining the Sierra de Los Filabres, the Sierra Nevada, the Sierra de Gador, and the Ma´laga Mountains, and their related beaches constitute a metamorphic–sedimenticlastic quartzolithic sand petrofacies (Qm34610 F463 Lt6269; Lm72614 Lv264 Ls26613), derived dominantly from the Nevado–Fila´bride, Alpuja´rride, and Mala´guide complexes. This quartzolithic petrofacies extends from northeast of Almeria to Torremolinos (southwest of Ma´laga), and northeast of Algeciras. Only one beach sand sample, east of Cabo de Gata, is volcanolithic. Volcanic detritus (mainly having felsitic textures) is derived from Miocene (15–7 Ma) pyroclastic sequences cropping out in the southeast of the chain. This metamorphic–sedimenticlastic quartzolithic petrofacies changes in the coastal stretch from Torremolinos to Marbella, where drainage systems cut across the Serrania de Ronda. Here source rock types include peridotite, gabbro, and serpentinite of the Ronda Peridotite Massif, and metamorphic rocks of the Ma´laguide and Alpuja´rride units. The fluvial and beach sands of this area are quartzolithic (Qm32612 F1063 Lt58611), and include abundant peridotite and serpentinite grains. The latter quartzolithic petrofacies changes abruptly from Algeciras to Ca´diz, where the sand becomes quartz-rich (Qm7765 F462 Lt1964). This sand petrofacies is derived predominantly from recycling of sedimentary sequences, mainly the quartzarenite turbidite units of the Gibraltar Arc (the Algeciras Flysch). This petrofacies is characterized by higher proportion of quartz grains and abundant sedimentary lithic fragments (Lm163 Lv161 Ls9863). The three onshore petrofacies plot in the recycled-orogen provenance compositional field and the lithic to transitional to quartzose recycled subfields of Dickinson (1985). They vary from lithic, to transitional and quartzose depending on their source lithologies in the Betic foreland fold–thrust belt. These actualistic petrofacies best describe the nature and distribution of sand petrofacies derived from a collisional fold–thrust belt where primary and recycled source rocks are interfingered. Deep-marine turbidites of the Alboran Basin have basinwide quartzolithic sands having close compositional relations with Betic Cordillera onshore sand petrofacies. Comparison of detrital modes from mainland to deep-marine environments provides a suitable basis for interpreting the Miocene to Pleistocene sand dispersal history in the Alboran Basin. These modern quartzolithic petrofacies are used to interpret analogous ancient collisional sandstone petrofacies of the Alpine orogenic belt of the western-central Mediterranean region and of other collisional orogenic systems, as a broader point of view.

First record of the giant squid Architeuthis sp. (Architeuthidae) in the Mediterranean Sea

The stranding of a female specimen of the genus Architeuthis, a species not previously recorded in the Mediterranean Sea, is reported from the southern Spanish coast (Alboran Sea, western Mediterranean). The geographical distribution of the species is discussed.

Ethylene in cherimoya fruit (Annona cherimola Mill.) under different storage conditions

Cherimoya fruits grown in the subtropical valleys of the southern Spanish coast were stored at 20 or 10 o C. Ethylene concentrations within the internal atmosphere of the fruits, determined by gas chromatography, show a peak coincident with the beginning of senescence at both temperatures. Production of ethylene was dependent on the storage temperature of the fruits. Implications of ethylene on the ripening of cherimoya are discussed