Search results for "Ostracod"

Ostracod palaeolimnological analysis reveals drastic historical changes in salinity, eutrophication and biodiversity loss in a coastal Mediterranean …

2013

The Albufera of Valencia, one of the largest oligohaline coastal lagoons of the Iberian Peninsula, has suffered hydrological and landscape modifications since medieval times. This paleolimnological study clears up the controversy about the factors, which drove the lake to its present state. Lithological descriptions, ostracod paleoassemblages and Cyprideis torosa (Jones, 1850) shell morphological variations and geochemistry (δ18O, δ13C and Sr/Ca) have been used to reconstruct the lake ecosystem evolution during the last two centuries. The sandy sediments at the bottom of L’Antina core (63 cm) presented a typical assemblage of brackish water ostracods, with shell-derived δ18O values, inferre…

Microcrustacean and Rotiferan Communities of Two Close Mediterranean Mountain Ponds, Lagunas de Bezas and Rubiales (Spain)

2010

ABSTRACT We compared two freshwater mountain ponds during an annual cycle by focusing on Rotifera and Crustacea. These ponds, Laguna de Bezas and Laguna de Rubiales, are located only 4.5 kilometers apart and share a similar altitude (ca. 1200 m.a.s.1) on the Iberian Mountain range, in Teruel (Spain). Bezas is near-permanent and dries out only in severe droughts; Rubiales is temporary, drying out periodically. They also show important differences in other limnological traits. Bezas has transparent water, harbors a fish population, and has a dense macrophyte cover, whereas Rubiales has elevated turbidity and neither fish nor macrophytes during most of the hydroperiod. These differences are pr…

Holocene paleoclimate inferred from salinity histories of adjacent lakes in southwestern Sicily (Italy)

2016

Marked uncertainties persist regarding the climatic evolution of the Mediterranean region during the Holocene. For instance, whether moisture availability gradually decreased, remained relatively constant, or increased during the last 7000 years remains a matter of debate. To assess Holocene limnology, hydrology and moisture dynamics, the coastal lakes Lago Preola and Gorgo Basso, located in southwestern Sicily, were investigated through several stratigraphic analyses of ostracodes, including multivariate analyses of assemblages, transfer functions of salinity, and biochemical analyses of valves (Sr/Ca, δ18O and δ13C). During the early Holocene, the Gorgo Basso and Lago Preola ostracode rec…

The influence of climate and sea-level change on the Holocene evolution of a Mediterranean coastal lagoon: Evidence from ostracod palaeoecology and g…

2013

Abstract Coastal lagoons provide an excellent basis for the study of processes controlling the evolution of a coastal zone. We examine the relative importance of these processes during the middle to late Holocene through a study of an 8.5 meter-long sediment record from the Albufera de Valencia (Spain). We combine sedimentological analyses with investigations into the palaeoecology, taphonomy and geochemistry (Mg/Ca, Sr/Ca, δ 18 O and δ 13 C) of ostracod valves in order to assess the effects of sea-level changes, storm events and effective moisture on the evolution of a Western Mediterranean coastal wetland. The late Pleistocene sediments represent a subaerial environment, which was followe…

Loss of Ostracoda biodiversity in Western Mediterranean wetlands

2008

1. The coastal area of Valencia (Spain) in the Western Mediterranean is rich in freshwater and brackish wetlands. These areas are mostly protected for bird conservation but are also highly affected by human impacts. Six shallow lakes located in Ramsar wetland sites of this area were studied in order to assess past and present ostracod biodiversity and relate it to the status of the lakes, taking into consideration the indicator value of these easily fossilizable crustaceans. 2. In all the wetlands studied, ostracod taphocoenoses showed much higher species richness than the corresponding biocoenoses. This is expected from the time accumulative character of the taphocoenosis, but the trend is…

Effects of environmental and spatial variables on lotic ostracod metacommunity structure in the Iberian Peninsula

2015

The heterogeneous distribution of aquatic species in lotic environments has been studied little in terms of metacommunity theory. Previous empirical tests have found significant spatial and environmental effects in pond and lake communities, but this has not yet been clearly established for stream networks. We conducted a multi-season survey of mountain streams in the Iberian Peninsula. We recorded GIS and in situ environmental data and collected biological samples to determine ostracods and macroinvertebrates and identified 41 ostracod species, the most common belonging to genera Herpetocypris , Sarscypridopsis , and Ilyocypris . A generalized linear model analysis showed that thermal rang…

Mutual Climatic Range Methods for Quaternary Ostracods

2012

Abstract The development of Mutual Climatic Range (MCR) methods for ostracods has included the estimation of marine bottom-water palaeotemperatures, but it has focused mainly on the use of non-marine ostracods to infer past air temperatures. The Delorme analogue MCR method, using only those components of a fossil assemblage that co-exist today, has yielded mean annual air temperature and annual precipitation estimates for North American Quaternary sites. The Mutual Ostracod Temperature Range (MOTR) non-analogue MCR method utilises all species in a fossil assemblage; calibrations based on a European database have been applied to the estimation of mean July and January air temperatures for En…

Freshwater ostracods (Crustacea: Ostracoda) of the circum-Sicilian islands

2007

Ostracods of Mediterranean temporary inland waters (Greece, Southern Italy, and Malta)

2015

Marine Ostracods of the Upper Miocene of the Well Ashtart 1 (Gulf of Gabès, Southeastern Tunisia)

1988

We studied the ostracod fauna from a Late Miocene-Early Pliocene interval 600 m thick, in Ashtart 1, an offshore well in the Gulf of Gabes, southeastern Tunisia. Most of the 131 samples analyzed contained rich and much diversified populations of marine ostracods. In fact, 212 species have been found, belonging to 70 genera. Among them, eight genera, 122 species and subspecies, considered as new, will be described elsewhere. In spite of contamination, usual in oil wells due to caving from higher levels previously drilled, some stratigraphical and palaeoenvironmental features have been established. The last occurrence datum of a selected group of species has been defined with accuracy, and so…