Dataset Information

A physico-chemical survey of inland lakes and saline ponds: Christmas Island (Kiritimati) and Washington (Teraina) Islands, Republic of Kiribati.

ABSTRACT: The equatorial Pacific Ocean atoll islands of Kiritimati and Teraina encompass great physical, chemical and biological variability within extreme lacustrine environments. Surveys of lake chemistry and sediments revealed both intra- and inter-island variability. A survey of more than 100 lakes on Kiritimati found salinities from nearly fresh to 150 ppt with the highest values occurring within the isolated, inland portions of the island away from the influence of groundwater or extreme tides. Dissolved oxygen (DO) and pH values also showed considerable variability with a less regular spatial pattern, but were both generally inversely related to salinity. Series of lakes, progressively more isolated from marine communication, present a modern analog to the chemical and morphologic evolution of presently isolated basins. Sediments on both islands consist of interbedded red and green silt, possibly degraded bacterial mat, overlying white, mineralogenic silt precipitate. Variability may be indicative of shifts in climatological parameters such as the El Niño Southern Oscillation (ENSO) or the Pacific Intertropical Convergence Zone (ITCZ).

SUBMITTER: Saenger C

PROVIDER: S-EPMC1533837 | biostudies-literature | 2006 Jul

REPOSITORIES: biostudies-literature

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A physico-chemical survey of inland lakes and saline ponds: Christmas Island (Kiritimati) and Washington (Teraina) Islands, Republic of Kiribati.

Saenger Casey C Miller Michael M Smittenberg Rienk H RH Sachs Julian P JP

Saline systems 20060703

The equatorial Pacific Ocean atoll islands of Kiritimati and Teraina encompass great physical, chemical and biological variability within extreme lacustrine environments. Surveys of lake chemistry and sediments revealed both intra- and inter-island variability. A survey of more than 100 lakes on Kiritimati found salinities from nearly fresh to 150 ppt with the highest values occurring within the isolated, inland portions of the island away from the influence of groundwater or extreme tides. Diss ...[more]

PMID: 16817958

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Project description:Ostracods are a diverse group of microcrustaceans with a ubiquitous distribution in a wide array of aquatic habitats and are common constituents of lake sediments. Inferences on the temporal-spatial distribution of ostracod species is a prerequisite for reconstructions of palaeoenvironmental conditions. This requires a precise knowledge not only about ecological preferences and specific life histories, but also the understanding how (local) ecological parameters affect ostracod species assemblages (abundance and composition). Generally, these studies are rare and often characterized by an insufficient differentiation of living specimens from the total amount of valves of the modern population leading to uncertainties in species occurrences and diversity data. Modern ostracod populations were sampled from 12 water bodies within a relatively small study area (Mansfeld lake area, Central Germany). Physico-chemical parameters (temperature, oxygen content, conductivity, pH) were measured in situ and the uppermost 2 cm of sediment were collected in different seasons (April, June, September). Relative abundances of ostracods (living and dead), differentiated for adults and juveniles, were used for statistical analyses (Spearman's rank correlation, Canonical correspondence analysis, Cluster analyses, Fisher's α), to investigate relationships between species distribution and environmental factors as well as to identify habitat similarities and ostracod species assemblages. In total, 27 ostracod species (20 living species) were identified. Majority of them are considered as very common (cosmopolitan) freshwater species. Only two species are usually known from brackish water (Cytheromorpha fuscata and Cyprideis torosa). This is the first confirmation of living C. torosa in German inland waters. The relative abundances of ostracods show strong fluctuations during the study period and differences in composition of the ostracod species assemblages between and within the water bodies. There are also strong differences between bio- and taphocoenoses. The measured physico-chemical parameters which are usually considered as most important drivers on ostracod species distribution do not contribute to explain the observed temporal-spatial distribution of the ostracod species. Differences in taphocoenoses show, that taphonomic processes can be very local and the sampling site, as well as the sampling time, is crucial. Biodiversity of ostracods is biased by sampling time, the variability of the ostracod assemblages between sampling month and the relationship between abundance of valves and living ostracods is not straightforward. Therefore, without precise knowledge of the ecological requirements of a species at a local scale, uncertainties may exist for the palaeoecological indication of a species.

Project description:ObjectiveIn some Pacific Island countries, such as Solomon Islands and Fiji, active trachoma is common, but ocular Chlamydia trachomatis (Ct) infection and trachomatous trichiasis (TT) are rare. On Tarawa, the most populous Kiribati island, both the active trachoma sign "trachomatous inflammation-follicular" (TF) and TT are present at prevalences warranting intervention. We sought to estimate prevalences of TF, TT, ocular Ct infection, and anti-Ct antibodies on Kiritimati Island, Kiribati, to assess local relationships between these parameters, and to help determine the need for interventions against trachoma on Kiribati islands other than Tarawa.MethodsAs part of the Global Trachoma Mapping Project (GTMP), on Kiritimati, we examined 406 children aged 1-9 years for active trachoma. We collected conjunctival swabs (for droplet digital PCR against Ct plasmid targets) from 1-9-year-olds with active trachoma, and a systematic selection of 1-9-year-olds without active trachoma. We collected dried blood spots (for anti-Pgp3 ELISA) from all 1-9-year-old children. We also examined 416 adults aged ?15 years for TT. Prevalence of TF and TT was adjusted for age (TF) or age and gender (TT) in five-year age bands.ResultsThe age-adjusted prevalence of TF in 1-9-year-olds was 28% (95% confidence interval [CI]: 24-35). The age- and gender-adjusted prevalence of TT in those aged ?15 years was 0.2% (95% CI: 0.1-0.3%). Twenty-six (13.5%) of 193 swabs from children without active trachoma, and 58 (49.2%) of 118 swabs from children with active trachoma were positive for Ct DNA. Two hundred and ten (53%) of 397 children had anti-Pgp3 antibodies. Both infection (p<0.0001) and seropositivity (p<0.0001) were strongly associated with active trachoma. In 1-9-year-olds, the prevalence of anti-Pgp3 antibodies rose steeply with age.ConclusionTrachoma presents a public health problem on Kiritimati, where the high prevalence of ocular Ct infection and rapid increase in seropositivity with age suggest intense Ct transmission amongst young children. Interventions are required here to prevent future blindness.

Dataset Information

A physico-chemical survey of inland lakes and saline ponds: Christmas Island (Kiritimati) and Washington (Teraina) Islands, Republic of Kiribati.

Publications

A physico-chemical survey of inland lakes and saline ponds: Christmas Island (Kiritimati) and Washington (Teraina) Islands, Republic of Kiribati.

Similar Datasets

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