CO2 and phosphate availability control the toxicity of the harmful bloom dinoflagellate Karlodinium veneficum

Abstract

We demonstrated that the toxicity of the harmful bloom dinoflagellate Karlodinium veneficum is regulated by both CO 2 concentrations and phosphate availability. Semi-continuous cultures were grown in a factorial experiment under all combinations of 3 CO 2 levels (230, 430 and 745 ppm) and 2 phosphate conditions (0.5 and 20 µM). After steady-state acclimation was achieved, karlotoxin cellular quotas and growth rates were determined in all 6 treatments. This strain produced both types of karlotoxin, KmTx-1 and KmTx-2. Chlorophyll a-normalized production of the 2 types of karlotoxins was much higher in P-limited cultures compared with P-replete ones under the same CO 2 conditions. Increasing CO 2 strongly stimulated production of KmTx-1 and decreased production of KmTx-2 in both treatments, but especially in P-limited cultures. Because the KmTx-1 toxin is an order of magnitude more potent than KmTx-2, total cellular toxicity was increased dramatically at high pCO 2 , particularly in P-limited cultures. Specific growth rates were accelerated by enriched CO 2 in P-replete cultures, but not in P-limited treatments. Growth rates or toxicity of K. veneficum could increase substantially in the future with high CO 2 levels in the ocean, depending on P availability, and so interactions between rising CO 2 and eutrophication could cause major shifts in present day patterns of harmful algal toxin production. These results suggest that over the coming decades, rising CO 2 could substantially increase karlotoxin damage to food webs in the often P-limited estuaries where Karlodinium blooms occur.

How will Ocean Acidification Affect Baltic Sea Ecosystems? An Assessment of Plausible Impacts on Key Functional Groups

“…Recent study has shown that the dinoflagellate Alexandrium ostenfeldii, a common (although typically not bloom forming) species in the central Baltic Sea, produces higher levels of saxitoxin under elevated pCO 2 (Kremp et al unpublished results). Similar results for other dinoflagellates have been found in other parts of the world (Fu et al 2010). No study has yet been done on the effects of increased pCO 2 on the common toxic bloom-forming dinoflagellates in the Baltic Sea, although these findings herald the possibility that nearfuture climate change may increase the toxicity of at least some of the algal blooms in the Baltic Sea.…”

Positive feedbacks between bottom-up and top-down controls promote the formation and toxicity of ecosystem disruptive algal blooms: A modeling study

“…Similarly, silica-and P-limitation increases cell quotas of the neurotoxin domoic acid in the diatom Pseudo-nitzschia multiseries (Pan and Rao, 1996;Pan et al, 1998;Sun et al, 2011). In addition, N-and Plimitation increases cellular karlotoxins by 2-to 15-fold in the dinoflagellate Karlodinium veneficum, which has caused fish-killing blooms (Adolf et al, 2009;Fu et al, 2010) and P-limitation causes over 10-fold increases in cell quotas of the toxin nodularin in the Nfixing cynaobacterium Nodularia spumigena, which has formed massive blooms in the Baltic Sea (Sunda et al, 2006). Thus, while our current model was constructed for Karenia brevis, similar positive feedback models should also apply to many other bloomforming, toxic species.…”

Bridging the Gap Between Ocean Acidification Impacts and Economic Valuation: Regional Impacts of Ocean Acidification on Fisheries and Aquaculture

“…Increased temperatures are thought to trigger proliferation of these harmful algae. While there are few studies investigate the potential impact of ocean acidification on the HABs, it has been recently demonstrated that CO 2 combined with limited nutrient enhanced karlotoxin and domoic acid production by Karlodinium veneficum (Fu et al, 2010) and Pseudonitzschia fraudulenta (Tatters et al, 2012), respectively. Ocean acidification and warming will occur in a background of chronic contamination of the coastal area through human discharges of contaminants.…”