jrscience.wcp.muohio.edu/birds/ohio_birds/ima...

1
Toxic Algae in Food Webs of Monterey Bay a CIMT
Study
UCSC RESEARCH TEAM
Principal Investigator Mary Silver Staff
Researchers Sibel Bargu Susan Coale Grad
Students Roz Antrobus Itcheung Chung Casey
Curtiss Cristy Sutherland Veronica
Vigilant Undergrads Suzanne Garcia
jrscience.wcp.muohio.edu/birds/ohio_birds/ima...
focus on toxic diatoms
2
BACKGROUND

• Historical data indicate toxic algae present
  since 1917 in California (Monterey Bay)
• Only 1 toxic alga studied (monitored ) until 1991
  (PSP agent)
• In 1991, bird deaths indicated the presence of
  another algal toxin (ASP)
• Deaths of numerous pinniped, cetacean bird
  species continue since 1991 (ASP toxins)
• Virtually nothing known of the regular pattern of
  offshore toxin producers on US west coast until
  2000 (taxonomic problems)
• Toxic algae affect human as well as marine animal
  and ecosystem health

3
CIMT Hypotheses Monterey Bay is a uniform
environment for toxic algae

• Toxic algae occur in similar abundance offshore
  and onshore
• Cells have similar toxicity offshore and onshore
• Temporal and seasonal abundance patterns are
  correlated offshore and onshore
• The well monitored SC wharf site reflects toxic
  algae events around the bay

Red tide (chlorophyll index)
4
1991 Food Web Toxin Domoic Acid
krill

• DA is acquired by herbivores that consume toxic
  diatoms Pseudo-nitzschia
• DA in herbivores is present as Pseudo-nitzschia
  detritus in the gut (not in body tissue)
• Carnivores acquire DA from toxic cell remnants
  in herbivore guts
• carnivores acquire DA at the site where
  herbivores are feeding on toxic cells
• DA Not your normal bioaccumulation pattern in
  food webs

Pseudo-nitzschia
blue whale
the source of Amnesic Shellfish Poisoning in
humans
5
Average densities of toxic Pseudo-nitzschia
(cells / L)
Pseudo-nitzschia the diatom that produces DA
(some species)
9.3 ( 3.5) x 103
6
Average densities Alexandrium (cells/L)
Average densities Alexandrium (cells/L)
Toxic Dinoflagellates
- Alexandrium catanella, the most toxic alga
known - the source of PSP (paralytic shellfish
poisoning) saxitoxin -motivation for
California shellfish monitoring and closures
since 1927
Average densities Dinophysis (cells/L)

• Dinophysis species complex
• source of diarrhetic shellfish toxins (okadaic
  acid etc.)
• Not presently monitored by state

7
Relationship of DA to toxic Pseudo-nitzschia
abundance
Data from all CIMT stations (SC wharf) 11/02-5/06
Stations where humpbacks and blue whales forage -
so. shelf and canyon edge stations
Reference station Santa Cruz wharf
Deep Water Stations - offshore
8
Correlation between temporal patterns of toxic
Pseudo-nitzschia at Santa Cruz wharf and CIMT
Stations
Correlation between Pseudo-nitzschia abundance
at Santa Cruz Wharf and CIMT Stations
Station n r p T100 22 0.09 gt 0.10 T101 28 0.50 lt
0.01 T102 23 0.54 lt 0.01 T201 25 0.65 lt
0.001 T301 29 0.09 gt 0.10 T401 24 0 gt
0.10 T402 29 0.60 lt 0.001 T501 27 0.57 lt
0.01 T601 25 0.70 lt 0.001 T701 25 0.002 gt
0.10 T702 28 0.08 gt 0.10
Baleen Foraging Stations
9
A Changing Pattern Amnesic vs. Paralytic
Shellfish Poisoning Algae 1999-2006?
ASP source toxic Pseudo-nitzschia diatoms
PSP source Alexandrium catanella dinoflagellate
10
Initial Results for CIMT Hypotheses Tested

• Abundances of toxic algae similar around the
  Bay
• Cell toxicity (DA and STX) higher offshore (deep
  water)
• Temporal patterns of cell abundance correlated
  between Santa Cruz wharf and most individual
  stations on south bay shelf and at canyon edge
  stations (including baleen whale foraging sites)

11
Other Study Outcomes

• Tracking the arrival of new toxic algae in the
  region
• Alerting with the California Health Department to
  potentially contaminated fish and shellfish in
  the region
• Recognizing that phytoplankton may be indicating
  longer term shifts related to oceanographic
  changes

12
THE END