| 1. |
- Dahl, Ulrika, et al.
(författare)
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Food quality effects on copepod growth and development : Implications for bioassays in ecotoxicological testing
- 2009
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Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier Inc. - 0147-6513 .- 1090-2414. ; 72:2, s. 351-357
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated effects of six algal species in 25 combinations on growth and reproduction of the harpacticoid copepod Nitocra spinipes. In the first lifecycle test, Rhodomonas salina, Phaeodactylum tricornutum, and Dunaliella tertiolecta were used. The results showed that R. salina was the best food, whereas P. tricornutum (0% development success) and D. tertiolecta (41.7% malformations) were poor food items. In the second lifecycle test, a mixture of R. salina, Tetraselmis suecica, and Thalassiosira weisflogii (selected from screening tests) was tested together with a mono-diet of R. salina. Also in this test, copepods fed R. salina performed better (i.e. had higher survival and reproductive success) compared with the other treatment. We conclude that R. salina is appropriate to use as food in toxicity testing with N. spinipes, whereas some of the algae commonly used as feed in ecotoxicological tests with other copepods had detrimental effects on the development, reproduction, and survival of N. spinipes.
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| 2. |
- Lind, Ewa, 1968-
(författare)
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Tephra horizons in the North Atlantic region during the Early Holocene
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Uncertainties about the rate and magnitude of future climate change have drawn attention to the climate variability following the Late Glacial-Early Holocene transition, c. 12-8 ka BP. Tephrochronology is a method that uses volcanic ash as isochrons in order to link, date and synchronise geological and palaeoclimatic records which could provide a better understanding of short rapid climate shifts but also the timing of these.The main purpose of this thesis was to improve and refine the Late Younger Dryas-Early Holocene (c. 12-8 ka BP) tephrochronological framework with focus on dating and identification of new and previously known tephra horizons in the North Atlantic region. A special emphasis was to identify tephra horizons contemporary to short rapid climate events that occurred during the period; the Preboreal Oscillation (c. 11.3 ka BP), the Erdalen events (c. 10.0-9.8 ka BP), the 9.3 ka BP and the 8.2 ka BP events. Additional purposes have been to evaluate the potential of XRF ITRAX core-scanning to identify tephra in lake sediments but also as a tool in palaeoclimate studies.The potential of tephrochronology for linking climate archives across the North Atlantic region is a main outcome in this thesis. Specific results include five new tephra horizons; four identified on the Faroe Islands and one in Central Norway. Two previously known tephras, the Hässeldalen and Askja-S tephras, were identified on the Faroe Islands for the first time and at new locations in Sweden which confirmed their widespread distribution in NW Europe. Several of these tephras have the potential to become marker horizons for some of the short rapid climate events which occurred during the Late Younger Dryas-Early Holocene but their importance is yet to be determined. Further results show that the XRF core scanner can be used successfully to identify high concentrations of basaltic tephra but also to identify palaeoclimatic events in lake sediments.
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| 3. |
- Lind, Ewa
(författare)
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Towards an Early Holocene Tephrochronology for the Faroe Islands: Methodology and first results
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The uncertainties regarding future climate change have put considerable notice to the climate variability following the Late Glacial-Holocene transition (ca. 13-9 ka BP) in the North Atlantic region as well as the forcing mechanisms behind climate changes. Much attention has focused on short climate events in order to understand the mechanisms that drove these changes but also to identify the leads and lags in the climate system. Chronological uncertainties for these events remain but an accurate chronological framework for the North Atlantic region would enhance possibilities to solve some of the chronological questions. Tephrochronology uses volcanic ash from a volcanic eruption which creates a marker horizon in marine and lake sediments, peat bogs and glacier ice as the ash is spread over large areas. These time-parallel markers allow precise correlations between archives. The purpose of this thesis is to improve and refine the Early Holocene tephrochronological framework with focus on dating and identification of new and previously known tephra horizons on the Faroe Islands, especially around the climatic events of the Preboreal Oscillation (11,300-11,100 cal. yr BP), the Erdalen events (10,100-10,050 and 10,000-9800 cal. yr BP) and the 9.3 ka BP event. A second goal is to develop the methodology of tephrochronology for finding cryptotephra (not visible by the eye) horizons in lacustrine sediments. The findings of eight tephra horizons spanning ca. 11,350 to 9700 cal yr BP where three are known from other locations in Europe show the potential of tephrochronology for linking records across the North Atlantic region. Refined ages for the Askja-S and Hässeldalen tephra were obtained from an age model built on eight AMS radiocarbon ages with the Saksunarvatn ash as a constrained age. The results from using XRF ITRAX core scanner to locate tephra in lacustrine sediments illustrate that high concentrations of basaltic tephra could be captured but not lower concentrations of rhyolitic shards.
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