Transcript Biodiversity Loss in Highly Altered Intertidal Habitats

SAWMILLS, SULIFIDE, AND SPECIES SURVIVAL:
Biodiversity Loss in Highly Altered Intertidal Habitats
Marissa Jones; Advisor: Joel Elliott
Intertidal Diversity Survey
Top side of rocks
1.6
1.3
Diversity
1
Top
0.8
Bottom
0.6
0.4
0.2
0
•Some taxa appeared to be more tolerant to
hydrogen sulfide than others.
1.2
Side of Rock
1.2
Hyde Park
ASARCO
1.1
Sulfide-Control
1
Control-Sulfide
Sulfide-Sulfide
0.9
Control-Control
0.8
Ruston Way
0.7
Location
0.6
29-Jul
Commencement Bay
3-Aug
8-Aug 13-Aug 18-Aug 23-Aug 28-Aug 2-Sep
Date
1.6
1.4
1.4
1.2
1.2
Diversity (H')
1.6
Side of Rock
1
Top
0.8
Bottom
0.6
Low
0.8
0.4
0.2
0.2
0
0
Medium
1
Control
Sulfide
Sulfide
Location
Location
Thatcher Bay
Underside of rocks
0.6
0.4
Control
Tidal Height
1
Diversity (H')
Rock from ASARCO site. The bottom
is covered in filamentous, sulfideoxidizing bacteria.
1.8
1.4
•Impacted sites were impoverished in species
diversity compared to control sites.
Diversity (H')
Rock from control area on Ruston Way.
• The Shannon Weiner Diversity Index (H’) was
calculated for the top and bottom of 15 rocks at 8
sites, 2 in Thatcher Bay and 6 in Commencement
Bay.
Transplant Experiment
Diversity (H')
Abstract
Organic pollution from historic lumber mills has
been deposited into marine sediments in Puget
Sound. Organic matter decomposes, releasing
hydrogen sulfide that is oxidized by white mats of
thiotrophic bacteria. These bacteria are a source
of increased primary production in the intertidal
zone, but sulfide is a potent toxin to most
organisms. To investigate the effects of organic
waste on intertidal organisms, former mill sites in
Commencement Bay in Tacoma and Thatcher
Bay on Blakely Is. were identified by the presence
of white bacterial mats. The Shannon-Weiner
Index (H’) was calculated for the top and bottom
of 15 rocks at three impacted and two control
sites. Diversity was significantly lower at the
impacted sites, and particularly on the bottoms of
the rocks. Diversity on rocks transplanted from
clean to sulfide sites decreased over five weeks.
Rocks transplanted from sulfide to clean
experienced the opposite effect. The relative
concentrations of sulfide and dissolved oxygen
were measured during an incoming tide. The
levels of sulfide decreased rapidly when exposed
to oxygenated seawater.
University of Puget Sound, Tacoma, Washington
Commencement Bay
Sulfide-Control
0.8
Control-Sulfide
0.6
Sulfide-Sulfide
Control-Control
0.4
0.2
5
Bacteria
4.5
Total Percent Cover (N)
Abundance (N or % Cover)
Oxygen
180
4
3.5
Commencement
Bay
3
2.5
2
Sulfide
1.5
Control
1
0.5
0
•Lumber mills deposited tons of organic debris into marine
sediments along Washington’s shoreline.
140
Control
120
Sulfide
Other
Mollusks
Annelids
80
3-Aug
8-Aug 13-Aug 18-Aug 23-Aug 28-Aug 2-Sep
Date
• Five rocks were transplanted according to the treatments listed
above and monitored for five weeks.
60
40
20
Decapods
Bryozoa
Sponges
Echinoderms
Taxonomic Group
Commencement Bay
Commencement Bay
0
29-Jul
100
0
Bivalves
Wood
Waste
160
• As predicted, the diversity of organisms on the undersides of rocks
transplanted from sulfide to control sites increased while the diversity
on rocks transplanted from control to sulfide sites decreased
(Repeated Measures ANOVA, p = 0.01).
•Organic material decomposes, releasing extremely high levels of
hydrogen sulfide, a potent toxin to most forms of eukaryotic life.
Sulfide
•In impacted areas, sulfide supports robust communities of
thiotrophic bacteria growing at the oxic/anoxic interface.
For Future Research…
Frequency and Duration of Stress
• Determine the spatial extent
of affected areas throughout
Puget Sound and Georgia
Basin.
• Explore the degree to which
intertidal animals can exploit
or tolerate hydrogen sulfide.
• Physiology
• Species interactions
San Juan
Islands
Thatcher Bay
Sampling site in Thatcher Bay on Blakely
Island, WA. Thatcher Bay was the site of the
largest lumber mill north of Seattle.
Transplant Experiment: Will the diversity of organisms living on rocks change
when the rocks are transplanted to or from a site impacted by organic
pollution?
Sulfide and Oxygen Levels: What is the frequency and duration of stress from
hydrogen sulfide and anoxia in impacted habitats?
• If biodiversity is to be fully
restored, the levels of organic
pollution need to be addressed
first.
9
100
10
900
8
90
9
800
7
80
8
70
7
60
6
50
5
40
4
30
3
700
6
600
5
500
4
400
3
300
200
2
20
2
100
1
10
1
0
0
1:01:55
0
0
11:11:00
11:14:20
Impacted Site
11:17:40
Time
11:21:00
11:24:20
1:03:22
Control site
1:04:48
1:06:14
Time
1:07:41
1:09:07
Are the bacteria living on this crab collected from
Commencement Bay helpful ectosymbionts, or just
hitching a ride?
Selected References
Oxygen (mg/L)
1000
Sulfide (uM)
Intertidal Diversity: To what extent do high levels of organic pollution affect the
diversity of intertidal animals and algae? Do species differ in their apparent
tolerance to hydrogen sulfide and anoxia?
• The concentration of hydrogen sulfide decreased dramatically when the rock came into
contact with oxygenated seawater.
Oxygen (mg/L)
Research Questions
• Investigate the role bacteria
play in these unique, sulfiderich habitats.
• For intertidal organisms living on the undersides of rocks, exposure to high levles of
sulfide is periodic and linked to low tides.
Sulfide (umol)
Sampling sites along Ruston Way on
Commencement Bay in Tacoma, WA.
Numerous mills operated along the shoreline.
Areas affected by wood waste in the intertidal
correspond with subtidal bacterial mats (Elliott
et al. 2006).
• A concrete block containing sulfide and dissolved oxygen probes was constructed so
that the probes measured the concentrations on the underside of the rock.
Measurements were taken during an incoming tide.
Acknowledgements
University of Puget Sound Summer Research Grant, Phi Sigma Slater Award,
Pierce Conservation District, Dr. Sandy Wyllie-Echeverria, University of
Washington Friday Harbor Laboratories, Dr. Peter Wimberger, Al Vallecorsa.