Southern right whale (Eubalaena australis) calf mortality at Península Valdés, Argentina: Are harmful algal blooms to blame? (original) (raw)
Related papers
2015
Península Valdés (PV) in Argentina is an important calving ground for southern right whales (SRWs, Eubalaena australis). Since 2005, right whale mortality has increased at PV, with most of the deaths (~90%) being calves \u3c3mo old. We investigated the potential involvement of harmful algal blooms (HABs) in these deaths by examining data that include: timing of the SRW deaths, biotoxins in samples from dead SRWs, abundances of the diatom, Pseudo-nitzschia spp., and the dinoflagellate, Alexandrium tamarense, shellfish harvesting closure dates, seasonal availability of whale prey at PV and satellite chlorophyll data. Evidence of the whales’ exposure to HAB toxins includes trace levels of paralytic shellfish toxins (PSTs) and domoic acid (DA) in tissues of some dead whales, and fragments of Pseudo-nitzschia spp. frustules in whale feces. Additionally, whales are present at PV during both closures of the shellfish industry (due to high levels of PSTs) and periods with high levels of Pse...
Aquatic Mammals, 2010
Unusually high concentrations of the neurotoxin domoic acid (DA) were detected in a minke whale (Balaenoptera acutorostrata) carcass recovered during a severe harmful algal bloom (HAB), which occurred in southern California in April 2007. Cell fragments of the toxigenic diatom Pseudonitzschia australis were observed in whale gastric fluid and feces, corresponding to a dominance of Pseudo-nitzschia spp. in the phytoplankton community at the time of stranding. A high abundance of otoliths from a prominent DA vector, the northern anchovy (Engraulis mordax), were recovered in whale stomach contents, indicating trophic transfer of DA via the food web. Whale feces contained 258 µg DA per gram sample, exceeding DA concentrations reported for any marine mammal. DA intoxication was identified as the cause of mortality of this animal, expanding on the limited understanding of the impacts of DA-producing HABs on large whales.
Aquatic Mammals, 2010
Unusually high concentrations of the neurotoxin domoic acid (DA) were detected in a minke whale (Balaenoptera acutorostrata) carcass recovered during a severe harmful algal bloom (HAB), which occurred in southern California in April 2007. Cell fragments of the toxigenic diatom Pseudonitzschia australis were observed in whale gastric fluid and feces, corresponding to a dominance of Pseudo-nitzschia spp. in the phytoplankton community at the time of stranding. A high abundance of otoliths from a prominent DA vector, the northern anchovy (Engraulis mordax), were recovered in whale stomach contents, indicating trophic transfer of DA via the food web. Whale feces contained 258 µg DA per gram sample, exceeding DA concentrations reported for any marine mammal. DA intoxication was identified as the cause of mortality of this animal, expanding on the limited understanding of the impacts of DA-producing HABs on large whales.
Harmful Algae
The gulfs that surround Península Valdés (PV), Golfo Nuevo and Golfo San José in Argentina, are important calving grounds for the southern right whale Eubalaena australis. However, high calf mortality events in recent years could be associated with phycotoxin exposure. The present study evaluated the transfer of domoic acid (DA) from Pseudo-nitzschia spp., potential producers of DA, to living and dead right whales via zooplanktonic vectors, while the whales are on their calving ground at PV. Phytoplankton and mesozooplankton (primary prey of the right whales at PV and potential grazers of Pseudo-nitzschia cells) were collected during the 2015 whale season and analyzed for species composition and abundance. DA was measured in plankton and fecal whale samples (collected during whale seasons 2013, 2014 and 2015) using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The genus Pseudo-nitzschia was present in both gulfs with abundances ranging from 4.4 Â 10 2 and 4.56 Â 10 5 cell l À1 . Pseudo-nitzschia australis had the highest abundance with up to 4.56 Â 10 5 cell l À1 . DA in phytoplankton was generally low, with the exception of samples collected during a P. australis bloom. No clear correlation was found between DA in phytoplankton and mesozooplankton samples. The predominance of copepods in mesozooplankton samples indicates that they were the primary vector for the transfer of DA from Pseudo-nitzschia spp. to higher trophic levels. High levels of DA were detected in four whale fecal samples (ranging from 0.30 to 710 mg g À1 dry weight of fecal sample or from 0.05 and 113.6 mg g À1 wet weight assuming a mean water content of 84%). The maximum level of DA detected in fecal samples (710 mg DA g À1 dry weight of fecal sample) is the highest reported in southern right whales to date. The current findings demonstrate for the first time that southern right whales, E. australis, are exposed to DA via copepods as vectors during their calving season in the gulfs of PV.
Heliyon, 2019
Harmful algal blooms (HABs) have been recorded in the Chubut Province, Argentina, since 1980, mainly associated with the occurrence of paralytic shellfish poisoning (PSP) toxins produced by dinoflagellates of the genus Alexandrium. PSP events in this area impact on fisheries management and are also responsible for severe human intoxications by contaminated shellfish. Within the framework of a HAB monitoring program carried out at several coastal sites along the Chubut Province, we analyzed spatiotemporal patterns of PSP toxicity in shellfish during 2000-2011. The highest frequency of mouse bioassays exceeding the regulatory limit for human consumption was detected in spring and summer, with average values of up to %70% and 50%, respectively. By contrast, a lower percentage of positive bioassays (2-8%) or no toxicity at all was usually detected during autumn and winter. The most intense PSP events were usually observed between November and January, with values of up to 4,000 μg STX eq 100 g À1 , and showed a marked interannual variability both in their magnitude and location. In addition, a severe PSP outbreak was recorded during autumn, 2009, at Camarones Bay, with toxicity values of up to 14,000 μg STX eq 100 g À1. The scallop Aequipecten tehuelchus showed significantly higher toxicity values compared to other shellfish species in SJG and SMG, suggesting a lower detoxification capacity. Our results contribute to the understanding of HABs dynamics on the Argentine Patagonian coast.
PLoS ONE, 2011
Sentinel species such as bottlenose dolphins (Tursiops truncatus) can be impacted by large-scale mortality events due to exposure to marine algal toxins. In the Sarasota Bay region (Gulf of Mexico, Florida, USA), the bottlenose dolphin population is frequently exposed to harmful algal blooms (HABs) of Karenia brevis and the neurotoxic brevetoxins (PbTx; BTX) produced by this dinoflagellate. Live dolphins sampled during capture-release health assessments performed in this region tested positive for two HAB toxins; brevetoxin and domoic acid (DA). Over a ten-year study period (2000-2009) we have determined that bottlenose dolphins are exposed to brevetoxin and/or DA on a nearly annual basis (i.e.