Ecosystem response to human- and climate-induced environmental stress on an anoxic coastal lagoon (Etoliko, Greece) since 1930 AD

Brauer, Achim; Zacharias, Ierotheos; Putyrskaya, Victoria; Klemt, E.; Sangiorgi, Francesca; Pross, Jörg

doi:10.1007/s10933-014-9823-1

Cited by 37 publications

(31 citation statements)

References 45 publications

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“…has been shown to produce microcystins toxins (Kyewalyanga and Lugomela 1999 ) and are associated with aquatic pollution (Ekwu and Sikoki 2006 ). Dictyocha fibula, a Dictyochophyceae species has been shown to be harmful to fish gills at high concentrations (Koutsodendris et al 2015 ). Based on the present study, the four sites have low nutrients but bear a problem of existence of toxic phytoplankton species.…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal variations in environmental variables in relation to phytoplankton composition and biomass in coral reef areas around Unguja, Zanzibar, Tanzania

Limbu

Kyewalyanga

2015

SpringerPlus

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Phytoplankton can indirectly indicate health status of coral reefs due to their sensitivity to changes in water quality parameters. This study explored the spatial and temporal variability in water quality and nutrients in relation to phytoplankton community composition and chlorophyll a concentration at Bawe, Mnemba, Chumbe and Pongwe coral reef sites in Unguja Island. In situ measurements of dissolved oxygen, temperature, salinity and pH were done every month for 1 year. Surface water samples were collected for determination of phytoplankton composition, nutrients and chlorophyll a concentration. Dissolved oxygen, temperature, salinity and pH did not differ significantly among the four sites (p > 0.05) but showed significant temporal variations among months (p < 0.05). Bawe had significantly higher phosphate concentration (1.45 ± 0.57 µg L−1) than Chumbe (0.74 ± 0.53 µg L−1), Mnemba (0.42 ± 0.30 µg L−1) and Pongwe (0.28 ± 0.10 µg L−1; p < 0.05). Similarly, Bawe had significantly higher nitrate concentration (0.81 ± 0.43 µg L−1) than Mnemba (0.33 ± 0.14 µg L−1) and Pongwe (0.24 ± 0.13 µg L−1; p < 0.05) but similar to Chumbe (0.90 ± 0.35 µg L−1; p > 0.05). However, values obtained at all the studied sites were less than 3 and 14 mg L−1 for phosphate and nitrate, respectively, for eutrophic oceans. Phytoplankton species were dominated by Bacillariophyceae (70.83 %) and some species identified such as Ceratium sp., Dinophysis sp., Protoperidinium sp., Prorocentrum sp., Oscillatoria sp. and Dictyocha fibula are known to produce toxins that affect fish species. Bawe had significantly higher chlorophyll a concentration (0.47 ± 0.07 mg L−1) than Mnemba (0.33 ± 0.04 mg L−1) and Chumbe (0.33 ± 0.04 mg L−1; p < 0.05). Chlorophyll a concentration was spatially inversely related to distance from Unguja town (p < 0.05) while it was temporally significantly positively correlated with dissolved oxygen, nitrate and phosphate (p < 0.05). The study revealed that, the coral reef sites have low nutrient levels and are in good health. The existence of toxic phytoplankton species suggests careful consumption of fisheries resources at the four coral reef sites and frequent monitoring for Harmful Algal Blooms (HABs) is required. The higher nutrients and chlorophyll a concentrations at Bawe Island compared to other sites calls for mechanisms to limit the release of domestic sewage from households and hotels to safeguard the coral reefs.

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Section: Discussionmentioning

confidence: 99%

Spatial and temporal variations in environmental variables in relation to phytoplankton composition and biomass in coral reef areas around Unguja, Zanzibar, Tanzania

Limbu

Kyewalyanga

2015

SpringerPlus

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“…Different large-scale atmospheric circulation patterns influence the Greek and eastern Mediterranean climate, such as the North Atlantic Oscillation (NAO), the Siberian High pressure system, and the East Atlantic/West Russia (EA/WR) pattern, mainly in winter, as well as the South Asian monsoon in summer (Barnston and Livezey, 1987;Xoplaki et al, 2003b, a). However, the rugged topography with its strong relief gradients and different mountain ranges acting as orographic boundaries lead to quite a heterogeneous modulation of these large-scale teleconnection patterns on a local level, influencing for example the amount of mean annual precipitation (Koutsodendris et al, 2017;Xoplaki et al, 2003a).…”

Section: Introductionmentioning

confidence: 99%

A 2600-year high-resolution climate record from Lake Trichonida (SW Greece)

Seguin¹,

Avramidis²,

Dörfler³

et al. 2020

E&G Quaternary Sci. J.

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Abstract. This paper aims at reconstructing the palaeoclimatic changes during the last 2600 years in southern Greece based on a proxy record from Lake Trichonida. For the first time, we provide a reliable age-depth model and continuous geochemical data for the largest and deepest lake in Greece. We use X-ray fluorescence (XRF) geochemical data supported by discrete mineral analysis based on X-ray diffraction (XRD), grain size distribution, and organic matter content to investigate changes in the lake sedimentary system and identify the major forcing mechanisms. A principal component analysis based on the XRF geochemical composition identifies the variation between carbonate-rich material, precipitating predominantly under drier and/or warmer conditions, and terrigenous sediment input, with it being more prominent during wetter and/or colder conditions. The first principal component (PC1) shows a very strong correlation with the weathering proxy log (Rb∕Sr), and we interpret both proxies as depicting fluctuations in the hydrological conditions. A cluster analysis, conducted on the continuous geochemical and colour parameters, highlights the similarities in the sediment characteristics deposited during wetter phases, notably during 1850–1750, 1500–1400, ca. 1100, and ca. 100 cal BP. When comparing the PC1 Trichonida record to independent records from the Balkans, we find generally concurring patterns on a multi-decadal to centennial scale. We show that phases with wetter conditions at Lake Trichonida coincide with a more negative North Atlantic Oscillation (NAO) index, suggesting that the precipitation variability in southern Greece is linked to changes in the NAO atmospheric pattern, as one major driving force. The 2600-year-long sedimentary record of Lake Trichonida contributes to a better understanding of Late Holocene palaeohydrological changes in an important climatic transitional zone in the eastern Mediterranean.

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“…The geological formations of the surrounding lagoon area can be distinguished to the Pliocene to Holocene clastic sediments and to the rocky basement that consists of Triassic limestone with evaporites and Eocene limestone ( Figure 1c). Furthermore, the geological evolution, depositional environments, and physicochemical conditions of the lagoon were studied by many researchers [15,[20][21][22].…”

Section: Study Areamentioning

confidence: 99%

The Influence of Olive Orchards Copper-Based Fungicide Use, in Soils and Sediments—The Case of Aetoliko (Etoliko) Lagoon Western Greece

et al. 2019

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In this study, soil and aquatic sediments were sampled in the Aetoliko Lagoon and its catchment area, which is exclusively dominated by olive orchards. For the first time in Greece, soil as well as sediments samples of one coherent protected aquatic ecosystem were directly compared. In order to determine the influence that the usage of copper-based fungicides have on the lagoon sediments and on the soils of the surrounding area, twenty five (25) soil samples from different olive orchards that are bordering the water body and ten (10) sediment samples from the bottom of the lagoon were taken. The samples were analyzed for total copper content (total digestion) and extractable copper (diethylenetriaminepenta acetic acid, DTPA, extraction method). Furthermore, soil/sedimentological and geochemical analyses such as pH, grain size, total organic carbon, total sulfur, total nitrogen, and calcium carbonate content were carried out. The results show that the total copper in soils ranges from 58.37 to 671.33 mg kg−1. In addition the DTPA-extractable copper in soils has an average value of 45.00 mg kg−1. The average value of total copper in soils (286.24 mg kg−1) is higher than the threshold value for the Cu concentration (100 mg kg−1) set by the EU countries. Total copper content in the lagoon sediments is lower than in soils and varies between 43.85 mg kg−1 and 71.87 mg kg−1. The DTPA-extractable copper in sediments is in low ranges from 0.14 to 0.60 mg kg−1. On average, the total copper value for the lagoon sediments (55.93 mg kg−1) exceeds the Toxicity Screening Value (25.20 mg kg−1) for Cu in freshwater sediments. From the present study, it is clear that, although the copper in soils of the surrounding lagoon area exceeds the threshold limit for ecological risk, the lagoon sediments are influenced in a smaller degree. Our study can be used as a valuable reference and baseline for future studies on the environmental monitoring of the Aetoliko lagoon, as well as for studies in similar ecosystems.

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Ecosystem response to human- and climate-induced environmental stress on an anoxic coastal lagoon (Etoliko, Greece) since 1930 AD

Cited by 37 publications

References 45 publications

Spatial and temporal variations in environmental variables in relation to phytoplankton composition and biomass in coral reef areas around Unguja, Zanzibar, Tanzania

Spatial and temporal variations in environmental variables in relation to phytoplankton composition and biomass in coral reef areas around Unguja, Zanzibar, Tanzania

A 2600-year high-resolution climate record from Lake Trichonida (SW Greece)

The Influence of Olive Orchards Copper-Based Fungicide Use, in Soils and Sediments—The Case of Aetoliko (Etoliko) Lagoon Western Greece

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