Theodora Boubonari

The green seaweed Ulva rigida as a bioindicator of metals (Zn, Cu, Pb and Cd) in a low-salinity coastal environment

The capacity of Ulva rigida as a bioindicator of Zn, Cu, Pb and Cd contamination in oligohaline coastal waters was investigated. Metal concentrations in U. rigida, water and sediments and several environmental variables were measured seasonally at four stations in the coastal section of the Evros River Delta, Aegean Sea. All four metals in sediments had a significant local variation; in particular, they decreased with increasing distance from the fluvial end-member of Evros River. Mean Zn, Cu, Pb and Cd concentrations in U. rigida were 61.0, 22.4, 6.1 and 1.1 m gg -1 dry weight, respectively. This macroalga, compared to other co-occurring macroalgal species, had a high metal accumulation capacity, mainly of Cu and Cd. Local patterns of Zn, Cu and Pb in U. rigida were similar to those in sediments, while that of Cd was not; moreover, Cu and Pb in U. rigida correlated positively with their sediment contents, suggesting that this seaweed satisfies the basic prerequisite for a bioindicator of these elements in oligohaline environments. No metal in U. rigida displayed a significant seasonal variation, and there was no significant variation in ambient concentrations. A negative correlation between Zn in U. rigida and water salinity was found, probably due to both a higher metal burden in the freshwater flowing in the study area and to a decrease in Zn uptake with increasing salinity; Cd in the macroalga correlated negatively with water column ammonium.

Iron, zinc, copper, lead and cadmium contents in Ruppia maritima from a Mediterranean coastal lagoon: monthly variation and distribution in different plant fractions

Metal concentrations and quantities were determined monthly in different fractions of the submerged angiosperm Ruppia maritima in Monolimni Lagoon, Aegean Sea. Concentrations were the highest in the roots, suggesting that the sediment-to-root pathway is a principal uptake route of metals. Most metals were equally distributed between rhizomes plus stems and leaves; Fe accumulated greatly in the rhizomes plus stems, whereas Cu occurred mostly in the leaves. Positive correlations were found between metal concentrations in different plant parts, suggesting metal translocation. Most metal concentrations in the different parts declined during the growing season. Iron and Cd accumulation was found to be associated with temperature, which strongly influences the plant growth; additionally, Fe and Cd concentrations in plant tissues were negatively correlated with leaf, rhizome plus stem biomass. Copper concentrations in the roots showed a converse monthly pattern. No metal concentration in plant fractions was positively correlated with concentrations in the water or sediments. Metal quantities (m gm -2 ) stored in the plant generally increased 2- to 4-fold during the growing season. Evidence that return to sediments is a major fate of these quantities is provided by the seasonal pattern in sediment metal concentrations.

Metal (Fe, Zn, Cu, Pb and Cd) concentration patterns in components of a macrophyte-based coastal lagoon ecosystem

Information on the metal biological fate in macrophyte-based coastal lagoons is provided; this information can contribute to the assessment of the environmental effects of metal pollution and to the development of predictive models for rational management of coastal lagoons. Iron, Zn, Cu, Pb and Cd concentrations in the dominant invertebrate and fish species of Monolimni Lagoon, Mediterranean Sea, as well as in potential major sources for metal accumulation in these animals (water, sediments, angiosperms, seaweeds), were measured. Principal Component Analysis (PCA) was conducted using metal concentrations in invertebrates and fishes. All five metal concentrations loaded significantly on the first PCA axis; however, Zn and Cu loadings were less significant than Cd and even less than Fe and Pb ones. The samples of deposit-feeding invertebrates were separated from those of the rest of the organisms (browsing, herbivorous and carnivorous invertebrates, carnivorous gobies and muscle tissues of detritivorous mullets) along the first PCA axis. Deposit-feeding invertebrates displayed the highest Fe and Pb contents, and in general, the highest or comparatively high Cd, Zn and Cu ones. Carnivorous gobies showed comparatively high Zn contents and carnivorous shrimps the highest Cu ones, while muscle tissues of detritivorous mullets had low metal loads. In addition, there was no essential increase in metal concentrations corresponding to the increasing trophic level (autotrophs, to herbivores, to carnivores). Our findings suggest that (a) the variability in Fe, Pb and Cd contents in invertebrates and gobies depends at least to some extent on interspecific differences in feeding habits—deposit feeders accumulated the highest metal amounts probably due to high rates of uptake from sediments, (b) the variability in Zn and Cu concentrations in these organisms depends also on other interspecific differences apart from those in feeding habits, (c) metal accumulation in mullet muscle tissues does not depend markedly on feeding habits and (d) the trophic transfer of macrophyte-bound metals to the coastal lagoon food web is of relatively minor importance.

Measuring ocean literacy in pre-service teachers: psychometric properties of the Greek version of the Survey of Ocean Literacy and Experience (SOLE)

The aim of the present study was to respond to the increasing demand for comprehensive tools for the measurement of ocean literacy, by investigating the psychometric characteristics of a Greek version of the Survey of Ocean Literacy and Experience (SOLE), an instrument that assesses conceptual understanding of general ocean sciences content, focusing on the knowledge component. Four hundred twenty-one pre-service primary school teachers participated in a cross-sectional study. The dichotomous Rasch model was used to examine the measurement properties of the SOLE, namely, person-item targeting and separation, reliability, dimensionality and differential item functioning (DIF). Steps were taken to improve the instrument, where any of these attributes were outside acceptable ranges. Results suggested that a modified SOLE showed an adequate fit to the Rasch model, is unidimensional, free of DIF, and is particularly well-suited to the population under study. Our findings suggest that the SOLE constitutes a valuable tool which can be applied to a different cultural context and population. The proposed use of the instrument could contribute to the assessment of the quality of marine education in school-based and non-formal education contexts and to the cross-cultural comparison of ocean literacy, which are prerequisites for the improvement of ocean literacy.

Greek Pre-Service Teachers’ Knowledge of Ocean Sciences Issues and Attitudes Toward Ocean Stewardship

Greek pre-service teachers’ level of ocean literacy was assessed using a revised questionnaire concerning ocean content knowledge and an instrument about ocean stewardship. Rasch analyses showed that the items of both measures were well targeted to the sample. Pre-service teachers possessed a moderate knowledge of ocean sciences issues and positive attitudes toward ocean stewardship; they obtained most information on ocean content from the Internet and mass media and less from formal education, nongovernmental organizations, books, and out-of-school settings. Students who mostly preferred the Internet and mass media scored significantly higher on the knowledge questionnaire. The results could contribute to the enhancement of teachers’ ocean literacy.