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Physiological responses of Ostreopsis ovata to changesin N and P availability and temperature increase
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. (Plankton Ecology)
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. (Plankton Ecology)
2013 (English)In: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 21-22, 54-63 p.Article in journal (Refereed) Published
Abstract [en]

Ostreopsis ovata is a benthic dinoflagellate that produces palytoxin and ovatoxins. Blooms of O. ovata causing human health problems and mortality of benthic fauna have been reported from many tropical and temperate marine waters. In the present study we examined the combined effects of temperature and different nutrient conditions on the biochemical composition, growth, toxicity and carbohydrate production of an O. ovata strain originating from the Tyrrhenian Sea. O. ovata cultures with N:P ratios of 1.6, 16 and 160 (N deficient, NP sufficient and P deficient, respectively) were grown at 20 °C and 30 °C. Biomass accumulation, growth rates, cell volumes, biochemical composition, cell toxicity and carbohydrate production in each treatment were studied. Results indicated that under nutrient sufficiency O. ovata biomass accumulation increased significantly compared to N and P deficiency and also that N limitation severely affected growth. The highest growth rates were recorded at 30 °C. Cellular contents and the atomic ratios of C, N and P were higher in the cells grown at 20 °C than in those grown at 30 °C. O. ovata cell volumes increased at 20 °C. N deficiency significantly increased cell toxicity. Toxicity per cell was higher at 20 °C, but per carbon was highest at 30 °C. The highest carbohydrate production was found in conditions of N deficiency and at the lower temperature.

Our study suggests that temperature increases due to global warming and nutrient enrichment of coastal waters stimulate the proliferation of O. ovata, particularly for the strains that have become adapted to warm temperate waters.

Place, publisher, year, edition, pages
Elsevier, 2013. Vol. 21-22, 54-63 p.
Keyword [en]
Ostreopsis ovata, Benthic dinoflagellate, Haemolytic activity, Temperature, Nutrient deficiency, carbohydrate production
National Category
Ecology
Research subject
Ecology, Aquatic Ecology
Identifiers
URN: urn:nbn:se:lnu:diva-22718DOI: 10.1016/j.hal.2012.11.006ISI: 000314553800007OAI: oai:DiVA.org:lnu-22718DiVA: diva2:574609
Available from: 2012-12-06 Created: 2012-12-06 Last updated: 2016-12-20Bibliographically approved
In thesis
1. Influence of Human-induced Environmental Changes on the Physiology of the Harmful Benthic Marine Microalga Ostreopsis ovata
Open this publication in new window or tab >>Influence of Human-induced Environmental Changes on the Physiology of the Harmful Benthic Marine Microalga Ostreopsis ovata
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focus on the influence of human-induced environmental changes on the physiology of Ostreopsis ovata; a toxic, benthic dinoflagellate, which form blooms in tropical and temperate marine waters. O. ovata produces palytoxin and ovatoxins and copious amount of mucilage, all of which have significant negative ecological impacts on the benthic ecosystems where they occur. Understanding the factors affecting O. ovata growth and toxin production is therefore of great importance if we are to understand how this species form such successful blooms. To accomplish this, growth, toxicity, carbohydrate accumulation and related physiological traits of two strains of O. ovata (one from Japanese waters and the other from Mediterranean waters) were studied in laboratory experiments. The cells were grown under the conditions simulating climate-induced changes (higher temperatures and acidification of marine waters) and eutrophication (increase of nitrogen and phosphorus in coastal ecosystems).

O. ovata showed strain-specific responses to the tested environmental changes. Higher temperatures increased growth and reduced the cell toxin quota of the Mediterranean strain while it decreased the growth and toxicity of the Japanese strain. Nutrient (nitrogen-N and phosphorus-P) sufficiency significantly increased O. ovata biomass accumulation. N deficiency markedly decreased the growth while it increased cell toxicity. Lower temperatures (20 - 25 °C) increased the particulate carbohydrate accumulation in both strains. Cell volumes, C (carbon), N and P cell quotas and atomic ratios of O. ovata were significantly higher when grown at 20 °C, than those grown at 30 °C. Acidification did not significantly affect growth and cell toxicity, but increased particulate carbohydrate accumulation. The combined effect of higher temperature and acidification delayed the onset of the blooms by 3 - 5 days, in relation to present temperature and pH conditions.

When extrapolating these results to natural marine ecosystems, it can be inferred that O. ovata occurring in lower-latitudes are growing optimally in the present climate conditions. On the other hand, the strains of O. ovata in higher-latitudes seem to have higher temperature optima than they have now at present conditions. Therefore, further expansion of O. ovata blooms is most likely possible in the warm, eutrophic coastal waters in higher-latitudes.

Place, publisher, year, edition, pages
Växjö: Linnaeus University Press, 2013
Series
Linnaeus University Dissertations, 127/2013
Keyword
Ostreopsis ovata, benthic dinoflagellate, climate change, temperature increase, nutrient enrichment, acidification, physiology, cell growth, cell toxicity, carbohydrate accumulation
National Category
Natural Sciences
Research subject
Natural Science, Aquatic Ecology
Identifiers
urn:nbn:se:lnu:diva-24901 (URN)978-91-87427-17-6 (ISBN)
Public defence
2013-04-26, Fullriggaren, Barlastgatan 11, Kalmar, 09:30 (English)
Opponent
Supervisors
Available from: 2013-04-10 Created: 2013-03-26 Last updated: 2014-02-25Bibliographically approved

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Publisher's full texthttp://www.sciencedirect.com/science/article/pii/S1568988312001631#

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