Effect of pH on growth and domoic acid production by potentially toxic diatoms of the genera Pseudo-nitzschia and Nitzschia

Abstract

The effect of elevated pH on growth and on production of the neurotoxin domoic acid was studied in selected diatoms belonging to the genera Pseudo-nitzschia and Nitzschia. Growth of most of the 11 species studied stopped at pH values of 8.7 to 9.1. However, for P. delicatissima and N. navis-varingica the pH limit for growth was higher, 9.3 and 9.7 to 9.8, respectively. A compilation of all available data on the pH limits for growth of marine planktonic diatoms suggests that species from ponds and rock pools all have higher limits than coastal and oceanic species. Taking only coastal and oceanic species into account, the data suggest that smaller species have a higher upper pH limit for growth than larger species. Elevated pH induced production of domoic acid in P. multiseries in amounts comparable to those detected previously under silicate and phosphate limitation. As Pseudo-nitzschia species are found in high concentrations in nutrient-enriched areas, high pH and hence induction of the production of domoic acid would be expected during blooms. These results may help to understand when and why Pseudo-nitzschia species produce domoic acid in the field.KEY WORDS: Cell volume · Diatom · Domoic acid · Growth rate · pH · Phytoplankton · Pseudonitzschia · Toxin production Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 273: [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] 2004 Pseudo-nitzschia spp. blooms are often found in coastal areas enriched by nutrient-rich freshwater runoff (Smith et al. 1990, Horner & Postel 1993, Dortch et al. 1997, Scholin et al. 2000, Odebrecht et al. 2001 or in upwelling areas (Abrantes & Moita 1999, Trainer et al. 2000, Villac & Tenenbaum 2001. A positive relationship between increasing eutrophication of coastal waters and the abundance of Pseudo-nitzschia spp. was found in present and historical data from the coast of Louisiana and Texas (Dortch et al. 1997, Parsons et al. 2002. Hence, nutrient enrichment may result in increased densities of phytoplankton organisms such as Pseudo-nitzschia spp.In seawater, pH has generally been recognised as being very stable (pH ≈ 8.2), as it is buffered by the carbonate system. However, uptake of dissolved inorganic carbon (DIC) during photosynthesis by high densities of phytoplankton may actually cause an increase in pH, and thus high pH values (around pH 9) have been recorded in natural environments during algal blooms (Hinga 1992, Macedo et al. 2001. For instance, in Narrangansett Bay, USA, 18% of the samples had pH values above 8.7 (Hinga 2002). Similarly, during the development of a bloom of the haptophyte Phaeocystis spp. in the North Sea, Brussard et al. (1996) found an increase in pH from 7.9 to 8.7. In fjords and coastal lagoons, pH values can attain even higher levels, and pH values up to around 10 may then be found during bloom periods (e.g. Marshall & Orr 1948, Macedo et al. 2001, Hansen 2002. The only study that we have been able to find in which pH, growth of potentially t...

Induction of domoic acid production in the toxic diatom Pseudo-nitzschia seriata by calanoid copepods

“…Colony formation in the green algae Scenedesmus also seems to be induced by special grazer-released infochemicals rather than by excretory products of the grazers, or other nutrients (Lürling, 2001).pH is known to affect DA production in Pseudo-nitzschia species but the results from studies are contradictory. Lundholm et al (2004) and Trimborn et al (2008) found that elevated pH increased DA cell quota in P. multiseries, whereas Sun et al (2011) showed that the DA levels of P. multiseries increased with lowered pH. In the present study, pH is expected to increase as CO 2 is used for photosynthesis, but it is likely to be counterbalanced by the respiration of the copepods that produce CO 2 .…”

“…nutrients in relation to the growth phase (reviewed in Bates, 1998;Lelong et al, 2012), pH (e.g. Lundholm et al, 2004), and trace metal limitation or toxicity (Maldonado et al, 2002). Evidence of allelopathic effects of DA, however, has not been found (Lundholm et al, 2005).…”

Effects of nutrients, salinity, pH and light:dark cycle on the production of reactive oxygen species in the alga Chattonella marina

“…The possibility also exists that elevated pH may affect metal speciation and reduce the bioavailability of iron (McKnight et al, 2001;Lundholm et al, 2004), which may in turn enhance ROS production.…”

Domoic acid uptake and elimination kinetics in oysters and mussels in relation to body size and anatomical distribution of toxin

“…For bivalve experiments, cultures were scaled up in 10-20 l glass carboys with a continuous supply of filtered air (PTFE membrane filters, 0.2 m particle retention, Pall Co.) and harvested at stationary growth phase, when maximum toxicity was attained. Cell size was determined using a microscope (Leica model DMLB 100S) with a coupled Pulnix camera (Model TMC-7DSP) and image analysis software (Image Pro Plus Version 4.5, Media Cybernetics); cell volume was calculated by the formula described in Lundholm et al (2004) and simplified as: cell volume ( m 3 ) = 0.8 × L × W 2 , where L and W are the cell length and width, in m, respectively. Cell density was measured by microscopic counting of diluted samples (n ≈ 400 cells) on Palmer-Maloney chambers.…”