Distribution, Abundance and Domoic Acid Analysis of the Toxic Diatom Genus Pseudo-nitzschia from the Chesapeake Bay

Abstract

Very little research has been conducted on midAtlantic estuarine populations of the diatom Pseudonitzschia despite recent evidence of toxicity in regional isolates. We collected field samples from the Chesapeake Bay region from 2002 to 2007 for Pseudo-nitzschia enumeration and toxin analysis. Abundances of Pseudonitzschia were highest in the winter and spring at ∼10 3 cells ml −1 . Domoic acid (DA) was detectable in 42% of samples tested, but concentrations were generally low, ranging from 0 to 1,037 pg DA ml −1 (mean 176 pg DA ml −1 ), and DA cell quota ranged from <0.1 to 49.4 pg DA per cell (mean 1.4 pg DA per cell). Although Pseudo-nitzschia populations were observed year round when salinity was ≥5, populations were highest from February to May when temperatures were low (2-15°C) and salinity relatively high (≥10). Six species of Pseudo-nitzschia were identified via transmission electron microscopy of the samples: P. pungens (Grunow ex Cleve) Hasle, P. calliantha Lundholm, Moestrup et Hasle, P. subpacifica (Hasle) Hasle, P. cuspidata (Hasle) Hasle emend. Lundholm, Moestrup et Hasle, P. fraudulenta (Cleve) Hasle and P. multiseries (Hasle) Hasle. P. callianthawas the most common and not previously reported from the Chesapeake Bay. Of these species, P. pungens, P. calliantha, P. cuspidata, P. fraudulenta and P. multiseries are known to produce domoic acid.

SEASONAL AND SPATIAL PATTERNS OF TOXIGENIC SPECIES OF Dinophysis AND Pseudo-nitzschia IN A SUBTROPICAL BRAZILIAN ESTUARY

“…Although Pseudo-nitzschia spp. are usually observed close to the mouth of estuaries (SPATHARIS et al, 2007;STOECKER, 2008), they can also occur at lower salinities, as was the case in several areas of Chesapeake Bay with salinities up to 6 (THESSEN; STOECKER, 2008) and in the present study, where they were observed at salinities as low as 14.…”

“…The species found in this study are regarded as eurythermic STOECKER, 2008;QUIJANO-SCHEGGIA et al, 2008;LIEFER et al, 2009;ANDERSON et al, 2010;LJUBESIC et al, 2011). The euryhaline and eurythermic features of both species pose serious potential implications for aquaculture.…”

“…Similar results were found in other environments with comparable geomorphological characteristics, such as bays and coastal inlets (THESSEN et al, 2005;SPATHARIS et al, 2007). For example, in Chesapeake Bay, USA, the most abundant toxin-producing species, P. calliantha, P. pungens and P. multiseries, occurred in elevated cell densities near the estuary mouth; but they were absent in areas with salinity < 6.0 in the inner sectors STOECKER, 2008). This pattern suggests that the abundance of Pseudo-nitzschia spp.…”

Species occurrence of the potentially toxigenic diatom genus Pseudo-nitzschia and the associated neurotoxin domoic acid in the Argentine Sea

“…In any case, there is a great inter-and intraspecific variability in DA cell quotas measured among Pseudonitzschia strains isolated into culture from different regions of the world (Trainer et al, 2012). In addition, highly variable cell quotas are typically found among natural Pseudo-nitzschia populations (Schnetzer et al, 2007;Thessen and Stoecker, 2008), but some of this apparent variability may be attributable to DA estimates based upon total cell densities of Pseudo-nitzschia, which usually includes several co-occurring species.…”

Pseudo-nitzschia physiological ecology, phylogeny, toxicity, monitoring and impacts on ecosystem health

“…Low Pseudo-nitzschia abundances and low, irregular DA concentrations may partially explain the lack of documented toxic events in the Chesapeake Bay (Thessen and Stoecker, 2008).…”