Trend, signal and noise in the ecology of Ostracoda: information from rare species in low-diversity assemblages

Slack, Jerry Marie; Kaesler, Roger L.; Kontrovitz, Mervin

doi:10.1007/978-94-017-1508-9_14

Cited by 5 publications

(5 citation statements)

References 5 publications

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“…Conversely, ostracoda are abundant from freshwater to hyperhaline environments and guarantee a great continuity of palaeoecological information (Rodriguez-Lazaro and Ruiz-Muñoz, 2012). Even if paralic environments with unstable environmental parameters are often characterized by oligotypic assemblages dominated by opportunistic taxa, rare species provide reliable information (Slack et al, 2000). Salinity is considered one of the major controlling factors affecting the distribution of ostracoda; therefore, this group is often applied for palaeosalinity reconstructions (Gliozzi and Mazzini, 1998;Marco-Barba et al, 2013;Amorosi et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Benthic foraminifera or Ostracoda? Comparing the accuracy of palaeoenvironmental indicators from a Pleistocene lagoon of the Romagna coastal plain (Italy)

Barbieri

Vaiani

2018

J. Micropalaeontol.

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Abstract. Integrated analyses of multiple groups of microfossils are frequently performed to unravel the palaeoenvironmental evolution of subsurface coastal successions, where the complex interaction among several palaeoecological factors can be detected with benthic assemblages. This work investigates the palaeoenvironmental resolution potential provided by benthic foraminifera and ostracoda within a Pleistocene lagoonal succession of the Romagna coastal plain (northern Italy). Quantitative approaches and statistical techniques have been applied to both groups in order to understand the main factors that controlled the composition of assemblages and compare the palaeoecological record provided by single fossil groups.The two faunal groups are characterized by the high dominance of opportunistic species (Ammonia tepidaAmmonia parkinsoniana and Cyprideis torosa); however, detailed palaeoecological information is inferred from less common taxa. Benthic foraminiferal assemblages are mainly determined by the frequencies of abnormal individuals and species related to high concentrations of organic matter, showing two assemblages: a stressed assemblage, consistent with a brackish-water environment subject to salinity and oxygen fluctuations, and an unstressed assemblage, which indicates more stable conditions. Despite the lower number of species, ostracoda show more significant differences in terms of species composition and ecological structure between their three assemblages, formed in response to a salinity gradient and indicative of inner, central, and outer lagoon conditions. The stratigraphic distribution of ostracod assemblages shows a general transgressive-regressive trend with minor fluctuations, whereas benthic foraminifera highlight the presence of a significant palaeoenvironmental stress.In this case, the higher abundance along the stratigraphic succession, the higher differentiation of the assemblages, and the well-defined relationship between taxa and ecological parameters determine Ostracoda as the most reliable fossil group for precise palaeoenvironmental reconstructions. Nevertheless, benthic foraminifera indicate palaeoenvironmental stress and can be used to refine the environmental interpretation in the presence of monospecific ostracod assemblages.

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Section: Introductionmentioning

confidence: 99%

Benthic foraminifera or Ostracoda? Comparing the accuracy of palaeoenvironmental indicators from a Pleistocene lagoon of the Romagna coastal plain (Italy)

Barbieri

Vaiani

2018

J. Micropalaeontol.

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“…To boost palaeoecological information in accordance with microfossil assemblage structure, ad-hoc cut-off values and data transformations were applied. The minimum threshold for retained benthic foraminifer and ostracod taxa was set at ≥4% in the marine sector (core 205 S9) and ≥2% in the wetland portion (core 205 S5), following Slack et al (2000). As for pollen in the inland zone (core EM2), a pre-selection was performed.…”

Section: Discussionmentioning

confidence: 99%

“…The minimum threshold for retained benthic foraminifer and ostracod taxa was set at ≥4% in the marine sector (core 205 S9) and ≥2% in the wetland portion (core 205 S5), following Slack et al . (2000). As for pollen in the inland zone (core EM2), a pre‐selection was performed.…”

Section: Methodsmentioning

confidence: 99%

Millennial‐scale shifts in microtidal ecosystems during the Holocene: dynamics and drivers of change from the Po Plain coastal record (NE Italy)

Rossi

Barbieri

Vaiani

et al. 2021

J Quaternary Science

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Framed into a robust stratigraphic context, multivariate analyses on the Holocene palaeobiological record (pollen, benthic foraminifers, ostracods) of the Po coastal plain (NE Italy) allowed the investigation of microtidal ecosystems variability and driving parameters along a 35-km-long land-sea transect. Millennial-scale ecosystem shifts are documented by coeval changes in the meiofauna, reflecting variations in organic matter-water depth (shallowmarine environments) and degree of confinement-salinity (back-barrier settings). In-phase shifts of vegetation communities track unsteady water-table levels and river dynamics in freshwater palustrine areas. Five environmental-ecological stages followed one another crossing four tipping points that mark changes in relative sea level (RSL), climate and/or fluvial regime. At the culmination of Mediterranean RSL rise, after the 8200 event, remarkable growth of peatlands took place in the Po estuary, while low accumulation rates typified the shelf. At the transgressive-regressive turnaround (~7000 cal a BP), the estuary turned into a delta plain with tidally influenced interdistributary embayments. River flow regime oscillations after the Climate Optimum (post-5000 cal a BP) favoured isolation of the bays and the development of brackish wetlands surrounded by wooded peatlands. The youngest threshold (~800 cal a BP), which led to the establishment of the modern delta, reflects a major avulsion of the Po River.

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“…Loxoconcha elliptica thrives best at about 10-20_ salinity. A study of Ostracoda in 16 surface samples from Lake Manzala by Slack et al (1995Slack et al ( , 2000 yielded low diversity but high abundance autochthonous assemblages dominated by Cyprideis torosa. Loxoconcha occurred at 12 stations.…”

Section: The Egyptian Delta Lakesmentioning

confidence: 99%

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et al. 2001

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This paper presents multi-proxy palaeolimnological analyses from recent sediments in the nine CASSARINA lakes in northernmost Africa, three from each of Morocco, Tunisia, and Egypt. The lakes are diverse, ranging from hypersaline to brackish lagoons and freshwater lakes from high to low conductivity and pH. The macrofossils analysed include fruits, seeds, and vegetative remains of plants, lagoon and freshwater Mollusca, a range of other aquatic animals, and from one site in each country, Ostracoda and Foraminifera. The diverse macrofossils are multi-proxy indicators of environmental change, and demonstrate changes in response to human activities in the catchments of all the lakes. The three Egyptian Nile Delta lakes have received massive inputs of freshwater due to modifications of the flow of the R. Nile culminating in the Aswan High Dam built in 1964. Elsewhere, water withdrawal is frequently a serious threat. One lake with high biodiversity in Morocco has been drained and cultivated, and a rare acid-water lake in Tunisia is in danger of drying up. The internationally famous Garaet El Ichkeul in Tunisia, which was so important for birds, has become permanently saline with a loss of diversity. All the lakes are affected by agricultural and/or urban runoff and are experiencing changes as a result of human activities. Several are in a marginally sustainable condition, whereas others are permanently damaged. Water is a valuable resource in dry countries. Lakes and rivers are under increasing threat in North Africa from water withdrawal for human use, and secondarily from eutrophication, pollution, and destruction of surrounding wetlands. The CASSARINA (Change, Stress, and Sustainability: Aquatic Ecosystem Resilience in North Africa) Project (Flower, 2001) aims to describe lake ecosystem changes in nine North African lakes over the last century and relate these to environmental changes and human impacts (stress) in their catchments. Such information is basic to the drawing up of wetland management and conservation plans. These need to be carefully considered, particularly in N. Africa, where technology is developing rapidly and where the understanding of aquatic ecosystems and the effects that exploitation and management will have on them is relatively poor (Mitchell et al., 1985). Lakes are scarce in North Africa and are valued as sources of water and of food (fish). They are also 'islands' of high habitat diversity and hence high biodiversity, and are therefore notable refuges for aquatic plants and animals as well as important habitats for birds, particularly those migrating to and from Europe. Other papers in this volume describe the historical and pollen records of major events in the catchments of nine lakes over the last century of accelerated technological development (Ramdani et al., 2001a; Peglar et al., 2001). Lake responses to these events can be traced by stratigraphical analyses of short sediment cores from the lakes. Diatoms (Flower et al., 2001), zooplankton and benthos (Ramdani et al., 2001b), polle...

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Trend, signal and noise in the ecology of Ostracoda: information from rare species in low-diversity assemblages

Cited by 5 publications

References 5 publications

Benthic foraminifera or Ostracoda? Comparing the accuracy of palaeoenvironmental indicators from a Pleistocene lagoon of the Romagna coastal plain (Italy)

Benthic foraminifera or Ostracoda? Comparing the accuracy of palaeoenvironmental indicators from a Pleistocene lagoon of the Romagna coastal plain (Italy)

Millennial‐scale shifts in microtidal ecosystems during the Holocene: dynamics and drivers of change from the Po Plain coastal record (NE Italy)

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