Juan Manuel Muñoz

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.

Late Holocene evolution of the southwestern Doñana National Park (Guadalquivir Estuary, SW Spain): a multivariate approach

Four phases are distinguished in the Late Holocene evolution of the southwestern Donana National Park (SW Spain), based on a multidisciplinary analysis of the sediments present in drill cores. In the oldest phase (>2400–2500 cal. yr BP), a coastal lagoon (the Roman Lacus Ligustinus) was recognized in the central part of this area, partly closed by the Donana spit and limited by fluvial levees. The following phase (∼2400–2200 cal. yr BP) is characterized by high-energy events, which caused the breakthrough of the Donana spit and the creation of new littoral strands in the inner areas. In the third phase (∼2200–2050 cal. yr BP), this new outlet was closed, coinciding with the progradation of the Donana spit. The last phase (∼2050 cal. yr BP–Recent) comprises three periods: (a) an unstable period (∼2050–1950 cal. yr BP), with the deposit of cheniers over the previous levees; (b) an infilling period, with a diminution of the marine influence; and (c) the appearance of temporary ponds between the emerged levees and cheniers.

Analysis of the recent storm record in the southwestern Spanish coast: implications for littoral management.

This work compares the geomorphologic evolution of the Huelva coast (SW Spain), some climatic-oceanographic data of the Cádiz Gulf and the recent storm record of this zone, covering the last 4 decades (1956-1996). An interesting correlation was found between the southwestern wind periodicity, the number of storm periods and the beach ridges observed in the main spits (El Rompido and Doñana). The spectral analysis of the wind time series permits to establish two most probable levels of periodicity: 6 and 9-10 years. Both periods coincide with the storm record and the creation of new beach ridges after a high-energy period. Beach damage, another storm-induced effect, was analysed by deducing different implications for the future management of tourist localities.

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.

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.

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.