SIMoN
  Sanctuary Integrated Monitoring Network
Monitoring Project

Phytoplankton toxins in critical prey species in the Monterey Bay National Marine Sanctuary

Principal Investigator(s)

  • Mary Silver
    University of California, Santa Cruz
  • Sibel Bargu
    University of California, Santa Cruz

Funding

  • SIMoN
  • NOAA MBNMS
Start Date: January 05, 2007
End Date: August 10, 2007

This study is a companion project to the program investigating the dynamics of critical prey species in the Monterey Bay National Marine Sanctuary (see Open Ocean Projects). Our project will significantly value-add new data, at modest cost, to the overall research effort, as it leverages the use of samples to be obtained by the main project team and contributes dietary and other information back to that team. There is a phenomenon that is increasingly evident in the sanctuary, namely the frequent presence and often negative effects of a natural phytoplankton toxin, domoic acid (DA). The toxin contaminates a wide range of organisms including critical pelagic prey species, which in turn become toxin vectors to their predators, including marine birds and mammal. This movement of the toxin up the food chain can result in dramatic and much publicized mortality events for birds and mammals. Thus our efforts focus on this relatively recently discovered phenomenon of a naturally occurring neurotoxin in the sanctuary and its conveyance throughout the system by prey species that are commonly present throughout much of the California Current upwelling system.

This project focuses on the analysis of the toxin, DA, in prey species and in prey gut samples, which typically contain the frustules (shells) of the toxin-producers, species of the diatom genus Pseudo-nitzschia. The toxin is conveyed to predators via the gut contents of their prey; that is, DA transmission to predators is accomplished almost entirely via the gut contents of prey, not their body tissues. Thus, the presence of DA cellular material in GI tracts of consumers is evidence of their contamination. Even apex predators will typically contain diatom debris in their gut or feces when poisoned by DA, if gut contents have not been voided. This study also uses chemical measures of toxin presence (High performance liquid chromatography or HPLC) to complement gut content analyses.

We will examine two different types of prey samples collected in the Monterey Bay region: 1) “historical” samples, preserved from collections made back to the 1950s, before the toxin and its producers were known, and 2) recently collected samples from 2000 onward, where there are environmental data on cell counts of the toxic species and DA in the water. The former will utilize samples from the CalCOFI project, the latter from samples collected in the sanctuary by colleagues. We will dissect thaliaceans (e.g., salps, doliolids) from the preserved, historical samples and examine the gut contents for DA frustules. Freshly collected specimens obtained by other reseachers will also be analyzed in the same fashion, but will also be analyzed for DA itself using HPLC. Additionally, we will have background water samples of toxic cell abundance and the DA from studies that we are conducting on other funded projects, data that will indicate the pelagic availability of the toxic phytoplankton to the prey.

The Monterey Bay region is the ideal place to study the phenomenon of natural toxins in food webs. First, it is one of the best known coastal ecosystems, due to its long history of marine research activities, which have shown the trophic connections among common pelagic organisms. Secondly, it is a system with the most extensive time series records of domoic acid presence in the world. Third, it has a well publicized history of toxic events, which began with marine bird mortalities and, most recently, has been tracked with strandings of sea lions that dramatically exhibit DA-poisoning symptoms. Lastly, we will collaborate with other researchers in the region to link the different tropic levels. We envision the outcome of this project to add significantly to our understanding of the extent to which key pelagic vectors provision apex predators with naturally occurring toxins and to provide an initial view of how long such a phenomenon may have been occurring in the inner waters of the California Current, where toxic phytoplankton have become such a common phenomenon.

Summary to Date

See the report at the bottom of this web page.

Discussion

Project Summary Here we propose a study that is a companion project to whichever team is funded to investigate the dynamics of critical prey species in the Monterey Bay National Marine Sanctuary. We believe our project will significantly value-add new data, at modest cost, to the overall research effort, as it leverages the use of samples to be obtained by the main project team and contributes dietary and other information back to that team. In our proposal we describe a phenomenon that is increasingly evident in the sanctuary, namely the frequent presence and often negative effects of a natural phytoplankton toxin, domoic acid (DA). The toxin contaminates a wide range of organisms including the pelagic prey species listed in this RFP, which then become toxin vectors to their predators, including marine birds and mammal, sometimes resulting in dramatic and much publicized mortality events. Thus our efforts focus on this relatively recently discovered phenomenon of a naturally occurring neurotoxin in the sanctuary and its conveyance throughout the system by prey species that are commonly present throughout much of the California Current upwelling system.

Our project is focused on the analyses of the toxin, DA, in prey species and the analysis of prey gut samples, which typically contain the frustules (shells) of the toxin-producers, species of the diatom genus Pseudo-nitzschia. Since the toxin is conveyed by vectors to their predators via gut contents (i.e. delivery of DA to predators is accomplished almost entirely via the gut contents, not body tissues of the prey), and thus the presence of the toxic cellular material in GI tracts of consumers is evidence of their DA contamination. Even apex predators will typically contain diatom debris in their gut or feces when poisoned by DA, if gut contents have not been voided. Thus this study uses both chemical measures of toxin presence (HPLC) and gut content analyses to show the role of toxin transmission by prey. We will examine two different types of prey samples collected in the Monterey Bay region, the first being “historical” samples, preserved from collections made back to the 1950s, before the toxin and its producers were known, to recently collected samples from 2000 onward, where there are environmental data on cell counts of the toxic species and DA in the water. The former will utilize samples from the CalCOFI project, the latter from samples collected in the sanctuary by colleagues. From these historical samples we will examine the gut contents of thaliaceans (e.g., salps, doliolids), which will demonstrate whether the toxic species were present, and krill, which will show whether a key prey taxon, was contaminated by the toxic species. The second category of samples will be freshly collected specimens obtained by the main team as well as specimens (squid, planktivorous fish) obtained from the commercial fleet in Moss Landing. This second category will be analyzed in the same manner as the historical samples, but will also be analyzed for DA, to more extensively establish the link between DA and the presence of toxic diatoms in their GI tract. From the main project team and the fishing community, we will analyze prey species for their DA and gut contents, to the extent to which the seagoing efforts provide us with prey species listed in this RFP. Additionally, we will have background water samples of toxic cell abundance and the DA from studies that we are conducting on other funded projects, data that will indicate the pelagic availability of the toxic phytoplankton to the prey.

The Monterey Bay region is the ideal place to study the phenomenon of natural toxins in food webs. First, it is one of the best known coastal ecosystems, due to its long history of marine research activities, which have shown the trophic connections among common pelagic organisms. Secondly, it is a system with the most extensive time series records of domoic acid and toxic phytoplankton presence anywhere, at least for DA. Third, it has a well publicized history of toxic events, which began with marine bird mortalities and, most recently, has been tracked with strandings of sea lions that dramatically exhibit DA-poisoning symptoms. Lastly, there is a possibility of researchers that combine the mix of phytoplankton specialists to experts on prey (and possibly apex predator researchers – if present on the main team) to work together, on this RFP to link the connectivity in a direct and closely connected project, for the first time. We envision the outcome of this project to add significantly to our understanding of the extent to which key pelagic vectors provision apex predators with naturally occurring toxins and to provide an initial view of how long such a phenomenon may have been occurring in the inner waters of the California Current, where toxic phytoplankton have become such a common phenomenon.

Study Parameters

  • Distribution
  • Trophic association

Figures and Images




Documents