S. Haritonidis

Bioaccumulation of metals by the green alga Ulva rigida from Thermaikos Gulf, Greece

Abstract Fe, Pb, Cu, Zn and Cd concentrations in the green alga Ulva rigida C. Agardh and in the sediment and seawater were studied at five stations of the Thermaikos Gulf, which is the recipient of domestic and industrial wastes. The relative abundance of metals in U. rigida and seawater (concerning Zn, Pb, Cu, Cd) decreased in the order: Fe>Zn>Pb>Cu>Cd, whereas in the sediment the order was the same except in the case of Pb>Fe>Zn. The seasonal variation of metal concentrations in the alga was significant for Cd and Zn. The mean values in the alga increased from spring to fall reaching a maximum in October or June (only for Cu). These variations are discussed in relation to growth dynamics, the concentrations of metals in the environment and tissue age. The concentrations of all metals in the alga were distributed uniformly among the five stations. There is a significant positive correlation in U. rigida between Pb–Cu, Fe–Cu and Cd–Pb. Pb and Cu concentrations in the alga were positively correlated with the respective concentrations in the sediment. Pb, Zn and Cd values in U. rigida from the study area exceeded those in the same or other species of the genus from other areas. U. rigida could be regarded as an indicator species for Pb, Zn and Cd. ©

Seasonal and local variations of metal concentrations in the seagrass Posidonia oceanica (L.) Delile in the Antikyra Gulf, Greece

Abstract The accumulation of Fe, Pb, Zn, Cu, Cd, Na, K, Ca and Mg in the leaves of seagrass Posidonia oceanica (L.) Delile was studied in the Gulf of Antikyra. The investigated area was of interest because of the specific composition of its substrate (involving bauxite) and also because of the nearby discharge wastes from an aluminium factory. All metal concentrations in the phanerogam were evenly distributed at the seven stations where there were adequate data for analysis. Cd, K and Ca displayed significant seasonal variation with high concentrations in P. oceanica during summer and autumn and low levels in winter and spring. This variation could have been the effect of age-dependent distribution of these metals in the leaves. Significant variation was also evident in Pb concentrations, which was probably associated with the growth dynamics of Posidonia oceanica. Other factors playing a role were the biomass of calcareous epiphytes on the plant leaves (as concerns Ca) and the interactions of metals for binding by the plant tissues. The dependence of metal concentrations in the plant on their concentrations in the environment (sediment and seawater) was also relevant. A significant correlation was found between Cd concentrations in the plant and those in sediment. A comparison between metal concentrations in P. oceanica of the Antikyra Gulf and those of the species belonging to the subfamily Posidonioideae from other areas is also presented. Cu, Pb, Cd, Fe, Ca and Mg concentrations in P. oceanica in the study area were generally high.

Use of the green alga Ulva rigida C. Agardh as an indicator species to reassess metal pollution in the Thermaikos Gulf, Greece, after 13 years

The concentrations of metals (Mn, Pb, Fe, Zn, Cu, Cd,Co, Ni, Cr, Na, K, Ca, Mg) were determined in thegreen alga Ulva rigida, in the sediment andseawater of Thermaikos Gulf (Greece) during monthlysamplings in 1994–1995. This Gulf is the recipientof domestic and industrial effluents. Pb, Fe, Cu, Coand Cr concentrations in U. rigida at the studyarea were higher than those 13 years earlier andapparently came from different sources than those forZn, Cd and Ni. The relative abundance of metals inthe alga decreased in the order: Mg > Na > K >Ca > Pb > Fe > Mn > Zn > Cr, Cu > Ni >Co > Cd. Only Cu concentrations in the alga fromKalochori and Cd ones from Viamyl showed significantseasonal changes. Cu and Cd concentrations ingeneral followed the same pattern of variation, withminimum values in winter-spring. This pattern isdiscussed in relation to growth dynamics and tissueage. Only Pb concentrations in the alga showed asignificant positive correlation with concentrationsin the seawater. There were both positive andnegative correlations among some metals in the alga. It is concluded that U. rigida can be used as anindicator species, especially for Pb.

Metal content in Enteromorpha linza (Linnaeus) in Thermaikos Gulf (Greece)

Local distribution and seasonal variation of Fe, Pb, Cu, Zn and Cd in Enteromorpha linza, in sediment and in seawater, were studied in Thermaikos Gulf (Greece), to which domestic sewage and industrial effluents are discharged. The mean metal concentrations (±SE) in the alga and seawater decreased in the following order: Fe>Zn>Pb>Cu>Cd and in the sediment: Pb>Fe>Zn>Cu>Cd. Only Cu concentrations in E. linza had a significant local distribution. Cadmium, Pb and Zn contents in E. linza were at maximum in the Harbour, whereas Cu and Fe were mininum in the Harbour and maximum at Biamyl station. These distributions were similar to those in the environment. Lead in E. linza correlated positively with Fe and Zn and negatively with Cd.Seasonal variation of most metals, except Cd, in E. linza was not significant. Lead, Cu, Zn and Fe variations followed a similar pattern, with minimum values in spring and an increase in autumn or winter, whereas Cd content was lower in January and at maximum in April. These variations reflect growth dynamics of the alga. Iron and Cu concentrations in E. linza from Thermaikos Gulf were lower but Pb, Zn and Cd higher than those in Enteromorpha spp. from other locations.

Thiol pools and glutathione redox ratios as possible indicators of copper toxicity in the green macroalgae Enteromorpha spp. from the Scheldt Estuary (SW Netherlands, Belgium) and Thermaikos Gulf (Greece, N Aegean Sea)

Defence mechanisms against Cu toxicity were examined in two dominant Enteromorpha species from two coastal water types. The macroalgae were collected at three locations in the eulittoral of the Scheldt Estuary (Netherlands, Belgium) and the Thermaikos Gulf (Greece). For 10 days E. prolifera (Scheldt) and E. linza (Thermaikos) were incubated in seawater media of different salinities: 6, 9, 23 psu and 25, 30, 35 psu, respectively. In one series, media were enriched with 100 μg Cu l-1; responses were compared with those in controls with no extra Cu added. Enteromorpha, which is frequently used as a monitor species for heavy metal contamination, had relatively high Cu tissue levels (0.5–3.8 μmol Cu gdwt-1). Cu levels in E. prolifera controls (Scheldt) decreased with salinity; this was not the case with Cu levels in E. linza controls (Thermaikos). During the 10-d incubation algal protein contents and tissue Cu were rather stable. In E. linza (Thermaikos) algal protein contents were significantly lower than those of E. prolifera (Scheldt), although there was no indication for nitrogen limitation in E. linza. E. linza also had much lower glutathione pools than E. prolifera. Only under acute Cu stress (metal addition) did E. prolifera synthesise metal-binding thiols (phytochelatins). Phytochelatin pools are not suitable as an indicator of the Cu levels in these algae. The glutathione redox ratio GSH:(GSH + 0.5GSSG) was used as an indicator of (Cu-induced) oxidative stress. In E. prolifera (Scheldt) this ratio decreased with algal Cu content (P <0.05), from ~0.5 to ~0.2. The average glutathione ratios in Enteromorpha from the Scheldt and Thermaikos showed some oxidative stress induction with increasing algal Cu contents, however more clearly if Cu was added. As this redox ratio can also be influenced by environmental factors such as irradiance and desiccation, it may not be useful as an indicator for Cu-induced oxidative stress in situ.

A survey of the benthic flora in the National Marine Park of Zakynthos (Greece)

Abstract We studied the composition of the benthic marine macroflora in Laganas Bay (National Marine Park of Zakynthos, Ionian Sea, Greece). Seasonal samples were collected by SCUBA-diving from April 2001 to February 2003. A total of 182 taxa at specific and infraspecific rank of macroalgae was found, 146 of which are new records to Zakynthos Island and 12 to the Greek coasts. The vegetation of most of the rocky substrata is characterized by species of the canopy-forming genus Cystoseira, while that of soft bottoms is characterized by large meadows of Posidonia oceanica. Two other phanerogams (Cymodocea nodosa and the lessepsian immigrant Halophila stipulacea) also occur on soft bottoms, the former developing dense meadows, while the latter occurs in only a restricted area. The invasive green alga Caulerpa racemosa var. cylindracea was of frequent occurrence on hard and soft substrata.

Metal content of some green and brown seaweeds from Antikyra Gulf (Greece)

An analysis was made of the levels of Fe, Cu, Zn, Cd, Pb, Na, K, Ca and Mg in three green and four brown seaweeds, abundant in the Antikyra Gulf (Viotia, Greece). After Ca and the macroelements K, Mg, Na, the higher concentrations found were of Fe and Pb, with Fe>Pb. Cadmium content was low in most species. Differences between species and taxonomic groups were also considered. Fe, Zn, Cd and Ca in the green algaDasycladus vermicularis increased from March to July and had their maxima in summer or autumn (Cd), whereas Cu, Pb and Mg showed an opposite pattern of seasonal variation with maxima in winter. Cu, Zn, Cd and K inD. vermicularis were correlated with their concentrations in the sediment and not with their dissolved levels in seawater. Iron inD. vermicularis was positively correlated with Zn and negatively with Cd.

Cymodocea nodosa (Ucria) Aschers. as a Bioindicator of Metals in Thermaikos Gulf, Greece, during Monthly Samplings

Abstract Iron, Pb, Mn, Zn, Cu, Co, Ni, Cr, Cd, Na, K, Ca and Mg concentrations were determined in leaves, stems and roots/rhizoids of Cymodocea nodosa, in seawater and in sediment from monthly collections from the Thermaikos Gulf (Greece). Statistical analysis demonstrated that only Pb concentrations in the leaves and Co concentrations in the stems displayed significant seasonal variation. However, the variations of Cu, K and Na in the roots/rhizoids between the three seasons (spring, summer, autumn) were also significant. The concentrations of Pb in the leaves and Cu in the roots/rhizoids could, generally, be included in one group of seasonal variation with high values in winter and autumn and low in summer or spring, whereas Co in the stems and Na and K concentrations in roots/rhizoids followed the opposite pattern. The variation of the first group was discussed in relation to the growth dynamics of the plant and of the second seasonal variation with tissue age and with the role of metals in physiological processes. The iron and Mn content in the leaves and Cu in the roots/rhizoids of C. nodosa were negatively correlated with their total concentrations in the sediment and Ca dissolved in the seawater was correlated with the concentrations in the stems. The concentrations of Pb, Cu, Cd and Na in the leaves were correlated with those in the stems; Pb, Cu and Ni concentrations in the stems were correlated with those in roots/rhizoids and Pb in the leaves with those in roots/rhizoids. Leaves of C. nodosa had higher Zn, Cu, Cd, Mn, Ni, Co, K and Ca concentrations than in the stems, whereas roots/rhizoids had higher values of Cu, Cd, Fe, Ni, Co, Cr and K in comparison with stems. The Co and Zn content in the leaves was higher than in roots/rhizoids. Cymodocea nodosa in Thermaikos Gulf could be regarded as a bioindicator for Mn and Cu. Leaves seem to constitute a better bioindicator for Mn, while the best collection time for the plant to be used as a bioindicator for those metals is autumn.

Seasonal accumulation of metals by red alga Gracilaria verrucosa (Huds.) Papens. from Thermaikos Gulf, Greece

Concentrations of Fe, Pb, Cu, Zn and Cd were determined during one season in the red alga Gracilaria verrucosa, sediment and seawater from the Thermaikos Gulf, Greece. This region has been subject to change due to increases in industrial and domestic activities. The relative abundance of metals in G. verrucosa and seawater decreased in the order: Fe>Zn>Pb>Cu>Cd and in the sediment: Pb>Fe>Zn>Cu>Cd. Cadmium concentration in the alga correlated positively with that in seawater. There was positive correlation between Fe concentrations in the alga and those of the Zn and Cu. The concentrations of metals in the alga showed no significant differences between the stations. Lead, Zn and Cu concentrations in the alga were slightly higher at Biamyl, whereas Cd was higher at Perea and Fe at Nea Krini. Seasonal variation of metal concentrations in the alga was significant for Cd and Fe. Copper and Fe increased from winter to summer, whereas Cd was the opposite. Zinc concentrations were minimum and Pb concentrations were maximum during spring. These variations are discussed in relation to tissue age, life cycle, ambient concentrations of metals and other environmental conditions. Cd and Pb concentrations inG. verrucosa in the Thermaikos Gulf were higher and those of Cu and Zn were lower than in other species of the genus.

THE SHORT-TERM UPTAKE OF ZINC AND CELL MORTALITY OF THE SEAGRASS HALOPHILA STIPULACEA (FORSK.) ASCHERS.

ABSTRACT Zinc uptake in the upper (leaves) and lower ground parts (roots, stems, rhizoids) of Halophila stipulacea (Forsk.) Aschers, and leaf cell mortality were examined in laboratory experiments. The seagrass was incubated for 12 days in zinc concentrations between 10−4 and 10−7 M. At 10−6 and 10−7 M Zn concentrations, uptake was characterized by a rapid initial adsorption rate slowly decreasing up to the 4th day, after which an equilibrium was reached; the ‘equilibrium’ concentrations increased as the Zn in sea water increased. At the higher Zn concentrations (10−5 and 10−4M)the content in the plant continued to increase after the 4th day, perhaps due to the development of necrotic effects mainly evident in the teeth and epidermal cells as well as in the mesophyll cells of the leaves. A positive correlation between Zn content in the upper and lower parts of H. stipulacea was also found, whereas Zn uptake in leaves was significantly higher than in the root-rhizomes-rhizoids. It was also demonstrated tha...