María Luz González-Regalado

Comparative ecological analysis of the ostracod faunas from low- and high-polluted southwestern Spanish estuaries: a multivariate approach

Abstract The distribution and abundance of both living and total ostracod populations from the estuaries of the southwestern Spanish coast are discussed. A total of 68 species were obtained from 120 bottom samples collected in the channels, channel margins and salt marshes. Four assemblages were recognized in this area: (a) Urocythereis oblonga assemblage, with marine species well-represented in sandy substrates located near the mouths; (b) Loxoconcha rhomboidea assemblage, mainly developed in the quiet tidal channels conected with the main channels of the marine domains; (c) Loxoconcha elliptica assemblage, enclosing the most cosmopolitan and euryhaline species, very abundant in muddy sediments and low to moderate hydrodynamic conditions; and (d) Leptocythere porcellanea assemblage, only observed in the clayey-silty channel margins of the most protected ebb channels. In these transitional environments, very unfavorable conditions for the ostracod development were found in: (a) the erosional channels and channel margins; (b) most of the salt marsh samples with high subaerial exposure; and (c) sectors with high metallic pollution levels and acidic waters.

Multivariate analysis applied to total and living fauna: seasonal ecology of recent benthic Ostracoda off the North Cádiz Gulf coast (southwestern Spain)

Abstract Q -mode principal component analyses of ostracode percentages from 55 samples collected in summer and winter in the Huelva littoral zone (southwestern Spain) delimited four total associations and five living associations. Urocythereis oblonga, Palmoconcha guttata, Pontocythere elongata and Loxoconcha elliptica associations are represented both in the total and in the biocoenosis distributions. An additional biocoenosis association is characterized by Neocytherideis subulata and Callistocythere rastrifera , two minor species in the total distribution. Salinity differentiates the euryhaline Loxoconcha elliptica association (29–36%.) and four marine associations (> 34%.) Under marine conditions, grain size is the main factor delimiting the ostracod fauna, with the Urocythereis oblonga association living in coarser sandy sediments and the Palmoconcha guttata association being widely distributed in silty sands. The Neocytherideis subulata-Callistocythere rastrifera association prefer very fine sandy sediments, whereas the Pontocythere elongata association inhabits all types of substrate. In the estuary of the Tinto and Odiel rivers, one of the most polluted zones of Europe, study of the seasonal distribution of ostracodes and comparison with previous reports indicate some recuperation in this degraded system. Such species as Loxoconcha elliptica, Leptocythere tenera , or Cytherois fischeri , common in other Atlantic estuaries, are found. In some channel areas, however, the combined effects of metal pollution, medium-grain sand, dredging and strong bottom drift may cause the disappearance of living specimens in some sectors, both in summer and winter.

Freshwater ostracods as environmental tracers

This paper revises the response of freshwater ostracods to different environmental conditions and anthropogenic impacts, with a worldwide overview of the potential use of these microcrustaceans as bioindicators and several examples of applications in different scenarios. The development of either a single species or an ostracod assemblage is influenced by physical–chemical properties of waters (salinity, temperature, pH, dissolved oxygen), hydraulic conditions, bottom grain sizes or sedimentation rates. In addition to population and community changes, morphological and geochemical changes can also be detected in the ostracod carapace, which serves as a tracer of the water quality. All these features permit to delimit the spatial effects of urban sewages, mining effluents, agricultural wastes, watershed deforestation or road building. These data are the basis for the palaeoenvironmental reconstruction of cores, with an interesting application to archaeology. In addition, favourable results of recently developed bioassays, coupled with an important variability of local assemblages under changing conditions in both waters and sediments, suggest that these microcrustaceans may included between the most promising sentinels groups in freshwater areas. These microcrustaceans show high sensitivity to pesticides, herbicides, heavy metal pollution and oil inputs.

Los ostràcodos actuales de la laguna de Venecia (NE de Italia)

In the Venice lagoon, ostracods from 99 recent samples were studied. The biocoenosis is more abundant in the inner margin, near some little channels. The microfaunal analysis delimited three estuarine associations, with numerous valves of Cyprideis torosa, and one marine association (Pontocythere turbida). Salinity, hydrodynamics, nutrients and substrate are the main factors which control the distribution of these microorganisms. This distribution is very similar in other recent lagoons of Italy.

Impact of millennial mining activities on sediments and microfauna of the Tinto River estuary (SW Spain).

In this paper, we analyze two short cores collected in the Tinto estuary (SW Spain), and describe the palaeoenvironmental evolution of this area during the last two millennia, along with the influence of historical mining activities and recent industrial pollution on sediments and microfauna (foraminifera and ostracoda). Although there were no significant changes in the distribution of microorganisms, a first pollution period (0-150 AD) was recorded in high sediment pollution by Cu in the shallow palaeochannels of the middle estuary. During this period and the following 1700 years, tolerant pioneer species of both foraminifera and ostracoda were found predominantly in the inner, protected areas of the estuary, while the bottom sediments were subjected to high hydrodynamic gradients, and consequently showed lower density and diversity of organisms. In the last 150 years, acid mine drainage processes, introduction of a new mining period, and the polluted inputs derived from two industrial processes resulted in increased heavy metal contamination of the bottom sediments, and corresponding extirpation of ostracodes and restriction of foraminifers to the inner zones of the estuary.

Virtual 3D tour of the Neogene palaeontological heritage of Huelva (Guadalquivir Basin, Spain)

Virtual fieldtrips in palaeontology and geology offer an expanded environment to make field sites more accessible for a broader audience. Based on extensive experience working in upper Neogene deposits in the province of Huelva, on the western edge of the Guadalquivir Basin, we have selected 10 sites for their regional palaeontological-geological interest (geosites). By applying geoinformatic tools, we have produced a virtual 3D tour of the georeferenced geosites, integrating multiple thematic digital layers (including geological maps, topographical maps, a digital terrain model and orthophotos). Each stop in the tour contains descriptive and graphic elements that can be viewed in free virtual globes (e.g., Google Earth), combined with diagrams, photographs and information sheets that quantitatively assess the cultural tourism, scientific and educational value of the geosite. From this digital 3D geodatabase, we propose a virtual flight itinerary that can be displayed in compatible video formats and using new technologies, such as smartphones, tablets or iPads.

Total benthic foraminifera assemblages in the southwestern Spanish estuaries

Abstract One hundred and twenty-one samples were collected in three estuaries of the Huelva littoral (SW Spain). The 12,923 individuals picked were assigned to forty-seven species. The analysis of the foraminiferal percentages allows the distinction of seven assemblages: two salt marsh assemblages ( Trochammina inflata and Jadammina macrescens ), four assemblages widely represented both in the channel margins and the channels ( Ammonia inflata, Astrononion stelligerum, Cribroelphidium vadescens, Ammonia ammoniformis ) and one marginal marine assemblage ( Ammonia beccarii-Quinqueloculina spp). The distribution of these assemblages is controlled by the salinity, the altitude above the lowest tidal level and, to a lesser extent, by the grain size, organic matter and the test transport. In the Tinto-Odiel estuary, both effects of heavy metal pollution and sedimentary changes in the foraminiferal distribution were analyzed, indicating some recuperation mainly in the Odiel river, one of the most polluted areas of the world.

The geological record of the oldest historical tsunamis in southwestern Spain

A regressive sequence was determined in the late Holocene evolution of the southwestern Donana National Park (SW Spain), based on a multidisciplinary study of sediments obtained in a drill core. In an initial phase (> cal. 2400 years BP), a shallow coastal lagoon with a partial marine connection occupied this area, with a progressive transition from subtidal to supratidal conditions. The following phase (cal. 2400-2350 years BP) is characterized by a tsunami, with the deposition of an upper chenier. This sedimentological layer is characterized by a ridge morphology, an erosive base, high bioclastic contents and the introduction of marine species toward the inner areas of this old lagoon. This tsunami may be assimilated to one of the historical tsunamis that occurred between 218 and 209 BC. A comparison with other deposits derived from these high-energy events permits to draw the differential effects produced along the western Iberian coasts. SHORT NOTES

Population age structure techniques and ostracods: Applications in coastal hydrodynamics and paleoenvironmental analysis

Abstract Ostracods are microcrustaceans that grow by moulting (eight to nine instars in most cases) and, consequently, studies of its populations need the application of some special techniques. The population age structure techniques [Whatley, in: Ostracoda in the Earth Sciences, 1988, pp. 245–256] are a simple statistical method to estimate paleoenvironmental conditions in fossil/Recent populations of ostracods. For its application, it is necessary to determine the percentages of each instar present in the samples studied, in order to analyze the different types of population age structure histograms and their (paleo-)environmental interpretations. Some potential applications are the (paleo-)energy levels or the sedimentation rates. In this paper, these special techniques are applied to Recent populations of the ostracod Pontocythere elongata collected in littoral sediments of southwestern Spain. In this area, the relative percentages of this species and the adult percentages are closely related with depth and consequently this species was used as a bathymetrical tracer in shallow Neogene areas of the Guadalquivir Basin. In addition, a first three-step multivariate analysis permits the definition of three groups, closely related to the theoretical models proposed by Whatley: (a) Group 1 structure or biocoenosis, present either in Recent low- to medium-energy environments located in erosional coastal stretches and Neogene fair-weather conditions; (b) Group 2 structure or high-energy thanatocoenosis, observed either in Recent river mouths with groynes and Neogene storm and post-storm conditions; and (c) Group 3 structure or low-energy thanatocoenosis, characteristic of Recent, progradational coastal areas and present in the Recent–Neogene deeper areas analyzed in this paper (30–40 m depth). This separation is mainly controlled by intrinsic factors (i.e. the natural growth of this species), whereas the extrinsic factors (i.e. the hydrodynamic levels) are only a minor cause of the distribution of this species in the area studied.

El género Heterostegina (Nummulitidae, Foraminifera) en el Mioceno superior del SO de España

Systematic study of specimens belonging to the genus Heterostegina from coquilla levels in the basal sandstone unit of the Neogene series in the western part of the Guadalquivir Basin (SW Spain). The specific determination of these specimens allows us to revise and emend the species Heterostegina gomez-angulensis Perconig. For the first time we describe and figure the microspheric generation of this species. The redescription of the megalospheric forms has permitted to differentiate two morphotypes. We discuss their chronostratigraphic significance.