What about HAB in Puget Sound? What caused the 50-y north-to-south spread of PSP?
Harmful algal species in PS Alexandrium catenella: paralytic shellfish poisoning (PSP) and diatoms in the genus Pseudo-nitzschia spp: domoic acid and amnesic shellfish poisoning (ASP) Heterosigma akashiwo: fish kills Chaetoceros convolutus and Chaetoceros concavicornis: fish kills
Harmful Algae in Puget Sound In 1942, 3 deaths in Washington State near the Strait of Juan de Fuca In 2000, 9 people became ill from eating mussels from Carr Inlet Large economic losses for shellfish farms and coastal business that benefit from recreational harvesting, in addition to the cost of monitoring
Saxitoxin Causes paralytic shellfish poisoning i (PSP) Symptoms (neurotoxin-sodium channel blocker) Tingling, g numbness, prickly sensation Incoherent speech, stiffness, noncoordination of limbs Muscular paralysis, respiratory difficulty, death Victims can survive severe poisoning with artificial respiration
Monitoring for PSP Butter Clam Littleneck Clam Blue Mussel Pacific Oyster
PSP in bivalves Toxins redistribute after contamination (Butter clams store PSP in siphons, perhaps as a predator defense) Residence time varies: mussels: weeks Butter clams: > 1 year
Alexandrium catenella Alexandrium produces saxitoxin. Saxitoxin accumulates in filter feeders. Responsible for PSP in humans who ingest contaminated shellfish. World s second highest toxin level found in Whidbey Basin, (30,360360 μgstxeq/100g shellfish meat). Highest (31,000) in BC waters.
Simplified life cycle of Alexandrium spp Gamete formation Vegetative population growth Planozygote Hypnozygote formation Germination Resting cysts Hypnozygote Bioturbation
Variation in observed paralytic shellfish toxins in sentinel bivalve species (Moore et al. 2008) Seasonal variation in PST closures in several locations in Puget Sound. Most in late summer & fall.
Studying cysts (Annie Cox, WWU graduate student)
Advection-diffusion equation applied to dinoflagellate ll cysts in sediment: Surface Layer C t x C C ( 1 ) D (1 ) u (1 ) C x x Bottom Layer C t C ( 1 ) u (1 ) C x
Excess 210 Pb to determine D and u Source: http://www.ozestuaries.org/indicators/images/pb210_diagram.jpg
Sequim Bay Measurable Saxitoxin every year since testing began in 1957 Increase in magnitude in more recent years Sequim Bay Monthly maximumpsp(stxeq/100gshellfishmeat) meat) Jul-06 Apr-04 Feb-02 Dec-99 Sep-97 Jul-95 May-93 Mar-91 Dec-88 Oct-86 Aug-84 May-82 Mar-80 Jan-78 Nov-75 Aug-73 Jun-71 Apr-69 Jan-67 Nov-64 Sep-62 Jul-60 Apr-58 Feb-56 0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000
Excess Pb-210 dating-sequim Bay Deep well-mixed surface layer Boundless diffusion coefficient D in cm 2 y -1 u in cm y -1 F in dpm cm -2 y -1 L in cm
Counted vs. predicted cyst profile Cysts from top to bottom of core Sequim Bay Cysts g -1 d.w. 0 200 400 600 800 1000 1200 1400 1600 0 5 10 15 20 Concentrations ranging g from 330 to 1381 cysts g -1 d.w. bottom (39.7cm), 1976 Depth (cm) 25 30 35 40 45 1983 1981 1979 1986 1984 1977 1976 2005 2003 2002 20001998 1996 1995 1993 1991 1990 1988 Pearson s s m= 0.71, p<.05, significant /g d.w.) cyst concentration (cysts/ 1400 1200 1000 800 600 Sequim Bay Measured 400 200 0 0 100 200 300 400 500 600 700 800 Predicted cyst concentration (cysts/g d.w.)
Carr Inlet 1981, 57 STXeq/100g shellfish meat. 1988, first time results exceeded closure level Closures have become common Carr Inlet Monthly maximumpsp(stxeq/100gshellfishmeat) meat) Oct-06 May-05 Jan-04 Sep-02 Apr-01 13,769 Dec-99 10,982 Jul-98 Mar-97 Oct-95 Jun-94 Jan-93 Sep-91 May-90 Dec-88 Aug-87 Mar-86 Nov-84 Jul-83 Feb-82 Oct-80 May-79 Jan-78 Aug-76 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Excess Pb-210 dating-carr Inlet Shallow well-mixed surface layer Boundless diffusion coefficient Highest sedimentation rate D in cm 2 y -1 u in cm y -1 F in dpm cm -2 y -1 L in cm
Counted cyst profile vs. predicted d cyst profile Zero at a depth of 29cm, 1985 Concentrations ranging from 0 to 33 cysts g-1 d.w. Depth (cm) 0 5 10 15 20 25 30 35 40 2005 Carr Inlet Cysts g -1 d.w. 0 5 10 15 20 25 30 35 2000.9 2000.1 1997.2 19964 1996.4 1995.7 1993.5 1992.7 1989.7 1995.0 1994.2 19881 1988.1 1987.4 1986.6 1985.8 1985.0 1984.2 1983.4 1982.5 1981.7 2001.5 1998.6 1997.9 1990.5 1988.9 1999.3 1991.2 2002.2 1992.0 2003.6 2002.9 2004.3 Carr Inlet bottom (33.3cm), 3 1982 Pearson s s m= 0.05, p>.05, insignificant 0 /g d.w.) cyst concentration (cysts/ Measured 35 30 25 20 15 10 5 0 2 4 6 8 10 12 14 16 Predicted cyst concentration (cysts/g d.w.)
Cyst Residence Time Divide the depth of the mixed layer by the sedimentation rate. Sequim Bay 37.7y Penn Cove 29.5y Carr Inlet 1.4y Potential for blooms continues for many years in Sequim Bay and Penn Cove, but not in Carr Inlet
Different relationships in different Sequim Bay cyst and PSP concentrations well correlated Carr Inlet no correlation Where do the Carr Inlet Alexandrium come from? Puget Sound basins
Is Quartermaster Harbor the source of HAB for the main basin of Puget Sound?
Mean water circulation patterns near Quartermaster Harbor, Vashon Island QUARTERMASTER HARBOR TACOMA
Coastal oceanography and Pseudo-nitzschia off the Washington State coast Pseudo-nitzschia produces domoic acid, which causes ASP Pseudo-nitzschia populations form high densities in a large eddy that occurs seasonally offshore of the SJF Pseudo-nitzschia populations sensitive to Fe concentration Data from http://www.ecohabpnw.org
Important areas of research on Puget Sound HAB: 1: Better predictions of timing and spatial extent of blooms 2: Development of HAB mitigation strategies cyst removal? clay flocculation? Penn Cove, Whidbey Island (Seattle P.I.)
Effects of future climate change? Predicted temperature rise in next 100y: 6 ºC Alexandrium cyst germination and bloom formation tied to water temperature (13 ºC) Trend (1993-2007) for PSP events to occur earlier in the year (Moore et al. 2008)