Download The Effects of Climate Change on an Intertidal Snail, Nucella

The Effects of Climate Change on an Intertidal Snail, Nucella canaliculata
1Department
Chelsie Wagner1 and Eric Sanford2
of Biology, Elon University; 2Section of Evolution and Ecology, University of California, Davis
Introduction:
Results:
Methods:
Climate Change - Although global climate change affects both air and
water temperatures,
p
, few studies have looked at how changes
g in both of these
abiotic factors might interact to impact organisms susceptible to marine and
terrestrial conditions such as intertidal organisms.
Acclimation vs. Synergistic Stress Response Four different
F
diff
t treatments
t t
t that
th t
manipulated both water and air
temperature were established.
Ambient Water (~12oC)
Warm Air (25oC)
Heated Water (16oC)
Warm Air (25oC)
There were 8 snails per source site
(Strawberry Hill or Bodega Head)
per treatment.
Water temperatures were maintained in two seawater tables (~12oC or 16oC). Air
temperatures during simulated low tides (3.5 hours daily) were attained with two
environmental
i
l chambers
h b
(1
(15oC or 2
25oC with
i h a gradual
d l ramp-up time).
i )
We tested two models for how increased air and water temperatures might
interact to influence intertidal organisms:
Acclimation vs. Synergistic:
Impact of Treatment and Source Site on Rates of
Predation in N. canaliculata
18
Strawberry Hill, OR
Bodega Head, CA
15
per Snail per 4 wks
Hypotheses:
Heated Water (16oC)
Cool Air (15oC)
# Mussels Drilled (+/- SE)
The habitats of these organisms are often restricted by abiotic factors including
temperature and as a result intertidal species may frequently live close to their
thermal limits. Consequently intertidal species may be greatly impacted by
small changes in temperature.
Ambient Water (~12oC)
Cool Air (15oC)
For snails from both populations,
the combination of cool water and
warm air (12C/25C) produced
strikingly lower feeding rates than
all the other treatments
(Tukey Kramer p<0
(Tukey-Kramer,
p<0.05).
05)
12
9
6
3
0
makes the organism more susceptible to thermal stress during warmer low tides
The snails were held in individual 0.5 L plastic containers that permitted waterflow and
were fed blue mussels, Mytilus trossulus, ad libitum. Every 7 days, each container was
opened to quantify rates of predation by counting and removing drilled mussels.
12C/15C
• Acclimation Model: the organism acclimates to the warmer conditions
dogwhelk Nucella canaliculata is a low
intertidal snail that feeds on mussels and
barnacles by boring a hole through their
prey’s shell with a radula and then using a
proboscis to consume the tissue.
In this study N. canaliculata from two different
sites, Strawberry Hill, OR and Bodega Head, CA
(right: labeled in red) were used to test whether
these populations differed in their response to
thermal stress.
The two treatments were created using stainless steel
mesh cages with either plexiglass windows to create a
greenhouse effect (n=5) or with a mesh cover to provide
shade (n=5). Each cage contained a prepared plate with
~30 barnacles, Semibalanus cariosus.
Ten paired plots were selected in a waveexposed low intertidal zone of the Bodega Marine
Reserve One pair of cages had no snails
Reserve.
(control). The other eight cages each received
two N. canaliculata collected from the
surrounding mussel bed.
Geographic
Range of
Nature Serve
N. canaliculata is a direct developer meaning
that its young hatch from egg capsules (above:
yellow in color) as crawl-away juveniles. As a
result, gene flow along its geographic range
(right: highlighted in blue) is low.
Predation by N. canaliculata was quantified in two
treatments designed to alter the body temperatures of the
snails during low tide
tide.
N. canaliculata
Data loggers were launched to moniter the
treatments. After two weeks preliminary barnacle
mortality rates were recorded.
Source Sites:
Strawberry Hill
Historical Analysis: Climate Change at Bodega Head -
and
Archived shoreline observations collected by the Bodega Ocean Observing Node were
analyzed for trends in changing ocean (surface) and air (low tide) temperatures.
Bodega Head
Community Consequences – Changes in
temperature that influence a predator’s feeding rate may alter
its impact on the prey community. The results of this study
are one piece in understanding the complex impact of climate
change on intertidal community dynamics.
Stop Global Climate Change –
Snails are not the only organism affected
by the rising level of greenhouse gases
in our atmosphere. There are ways in
which every individual can minimize their
carbon dioxide emissions. Check them
out and learn more about global warming
at http://www.stopglobalwarming.org.
Snails from Oregon consumed
significantly more than those from
California (ANOVA, p<0.001).
16C/25C
Impact of Different Air Temperatures During Low Tide on Rates
of Predation for N. canaliculata
With Snails
10
Barnacle mortality was not
significantly different between
shade and greenhouse
treatments (paired t-test,
p=0.279).
The temperatures experienced in
the different treatments has not
yet been recovered from the
data loggers.
Control
(no snails)
9
8
7
6
5
4
3
2
1
0
Greenhouse
Shade
Treatment
Surface Temperature at Bodega Marine Reserve
from 1957 to Today
y = 0.0284x - 44.645
R2 = 0.0973
16
A v e ra g e M o n t h ly T e m p e ra t u re
( d e g re e s C e ls iu s )
Eric Sanford
N canaliculata
N.
Study Species - The channeled
16C/15C
Manipulation of Air
Temperatures:
Manipulation of Air Temperatures –
experienced when submersed and is consequently more tolerant of elevated
air temperatures
12C/25C
Treatment Temperatures (Water/Air)
Rate of Predation per 2 wks
(barnacle mortality coun
nt +/- SE)
• Synergistic Model: thermal stress caused by warmer ocean temperatures
B th cooll water
Both
t temperature
t
t
(ANOVA, p< 0.001) and warm air
temperature (ANOVA, p<0.001)
significantly reduced drilling rates.
15
Climate Change at
Bodega Head:
14
Over the past fifty years, the
sea surface temperature at
the Bodega Marine Laboratory
has increased by 1.42oC.
13
12
11
10
The air temperature data are
still being analyzed.
analyzed
9
8
1955
1965
Discussion:
Population Consequences – Snail feeding rates were negatively impacted by warm air temperatures (25°C)
and this impact was strongest when water temperatures were cool (~12 °C). This suggests that increasing water
temperatures (such as those observed at Bodega Head since 1957) might help buffer snails against thermal stress
created by
y rising
g air temperatures.
p
These results support
pp the acclimation model.
1975
1985
1995
2005
Time (years)
Further Studies are underway to understand the effect of
warmer temperatures on the metabolic costs and growth
rates of N. canaliculata. It is expected that although the
snails acclimate to the warmer temperatures, their metabolic
costs are increased and thus their conversion efficiency and
growth rates are decreased.
North Wind
Surface
Water
Upwelling
of Deeper Water
Eric Sanford
The exact influence of climate change on future oceanographic conditions
is hard to predict. Water temperature during the summer months is
affected by coastal upwelling. Some predict that increasing inland
temperatures will intensify costal upwelling; as a result the intertidal area
might experience colder water temperatures during warm summer air
temperatures. This combination matches the treatment that had the
greatest negative impact on the snails in this study.
Acknowledgements: This work was
supported by grant #DBI-0453251 from the
National Science Foundation to S.L. Williams
and NSF grant #OCE-06-22924 to E.Sanford.
Thank you to the Sanford Lab, fellow REU
students, and BML community for their
guidance and support.