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Transcript of Final Eelgrass Scientific Paper Word
UNIVERSITY OF WASHINGTON, SEATTLE
How Eelgrass Origin Affects Performance in
Warm Water______________________________________________________________________
Gigi Gaultier1, Joanna Luse2, Malise Yun3
1. Gigi Gaultier. University of Washington, Seattle. [email protected]. 2. Joanna Luse. Eastern Washington University. [email protected]
3. Malise Yun. University of Washington, Seattle. [email protected]
December 9, 2016
Gaultier, 2
Abstract
The local eelgrass species in the Salish Sea, Zostera marina, serves as a nursery home to countless organisms in its environment. Understanding the response of eelgrass in different temperature environments can teach us about restoration transplantation throughout the Salish Sea and assure its health for the eelgrass and the organisms in and around it. Zostera marina generally thrives in an environment with a temperature range of 6-17 C but begins to decline in its performance once reaching a temperature of 25 C. Within the Salish Sea, the temperature of the water varies from location and throughout the seasons, ranging from 3 C in the winter to 23 C in the summer in just Padilla Bay, WA. We looked at the response in eelgrass shoots within two sites in the Salish Sea: Padilla Bay, a warm water location, and Ship Harbor, a cold water location. We tested these shoots in an environment with a gradual temperature increase from 14 C to 19 C for one month and a short term temperature increase to 30 C for 6 hours within that month. We found that growth in Zostera marina of Padilla Bay and Ship Harbor can be negatively affected in an environment with gradually increasing temperature for a long period of time. The short term temperature increase did not have as much of an affect due to the natural temperature variations during the summer in these two locations. Due to Padilla Bay eelgrass shoots coming from a warm location, we noticed that the shoots took a longer period of time to respond negatively than Ship Harbor eelgrass shoots. We think that this is because Padilla Bay is a warmer location so the shoots were more acclimated to that warmer temperature, but too long of a period of time can stress out the shoots too much that their performance begins to decrease. Keeping restoration transplantation in mind, the donor location matters. The temperature of the donor location must be similar to the environment in which it is being moved to or it will not survive.
Gaultier, 3
Question
How does eelgrass from different locations in the Salish Sea respond to
being warmed as predicted in 100 years and spiked with a higher
temperature to model extreme weather?
Introduction
Eelgrass, Zostera marina, plays an important plant role in ecosystems around
the Salish Sea. They are extremely vital when it comes to providing a habitat and a
food source for many organisms that live around them (Lee, 2007). Doing research
on eelgrass is important so that we can anticipate responses we might see in the
natural world. This underwater plant is very useful for ecological and economic
values. Eelgrass provides as a nursery for fish which can help support entire
fisheries (Raun, 2013). Eelgrass is found in most places across the globe of all the
seagrass species (Thom, 2014) and without its presence, entire environments would
change greatly in response. Although so important, scientists have been seeing
effects on this plant due to human stressors increasing through CO2, pollution and
temperature changes of global warming. The average rate of decline in seagrass
has increased by 9% from 1940s to 1990 due to these human stressors (Waycott,
2009).
Eelgrass has experienced a wide die off in high temperatures during the
summer (Nejrup 2008). Although many seagrasses are found throughout the world,
most all seagrass also increase growth through spring and summer and decrease in
fall and winter (Lee, 2007). Generally, once the summer temperatures hits their
high temperatures, eelgrass begins to decline and the process starts over again.
Gaultier, 4
But with global warming speeding up this process, recent studies have shown that
with a 1°C increase, 5 to 6 days in the eelgrass growing season is impacted on them
(Brodeur, 2015). Many experiments have been conducted on the stressors from
temperature change for
Gaultier, 4
eelgrass. The effects of temperatures higher than 30 C are where eelgrass shoots in
particular begin to decrease. This can include an increase of decay, bleaching and
diseases found on the leaves of the eelgrass (Neckles, 1999). Decaying disease can
be found through a darkening brown/black streaking and bleaching is a more white
tone that spreads throughout the leaf. The density and biomass of eelgrass shoots
also decreases as more shoots start dying off with higher temperatures extremes
(Thom, 2014).The optimal temperature for eelgrass survival is between 15-20 C
(Nejrup 2008), (Lee, 2007) but with global warming upon us, that is not always what
we get. Eelgrass over the world has decreased by 29% since 1998 (Waycott, 2009).
Finding the perfect temperature for Zostera marina can be difficult. In the
Salish Sea we have a range of temperatures that fluctuate throughout the year. In
the winter, the temperatures of Friday Harbor water can go down to 8 degrees C
and up to 15 degrees C in the summer (NOAA, 2016). This is the water that we will
be using to flow in for our water tanks, giving the eelgrass a slightly lower
temperature than what is most suitable for them. This will also make drastic
changes in the water temperature more noticeable. With global warming, water
temperatures are supposed to increase at a slightly faster rate, giving summer
temperatures “higher highs” than normal. With spiked increases from “the blob” (an
unusual drastic increase of temperature hitting the pacific northwest), areas in the
Puget Sound have increased as high as 2.2 degrees C higher than normal (Seattle
Times, 2015). This spike in temperature can shock the eelgrass and possibly give a
different response to eelgrass than a gradual increase. This leads us to our main
question of looking at the effect on Zostera marina from gradual temperature
increases vs extreme spike temperature increases.
Gaultier, 4
Looking at the effects of temperature rises, whether that be gradual or a heat
spike, is important for understanding the adaptability of these plants. With global
warming currently
Gaultier, 7
increasing the temperature of the oceans, we want to know if there is enough time
for eelgrass to be able to adapt to their changes and survive. Collecting shoots from
two different locations; Padilla Bay and Ship Harbor, allows us to see different
environments within the Salish Sea and how they each respond individually. When
slightly increasing the temperature of the water by a few degrees (C) in which the
shoots are in, it is a possibility that eelgrass will respond negatively to just an
overall increase. But testing an extreme spike increase, much like a heat wave, is a
short term effect that could make the eelgrass respond negatively from being
exposed to just an extreme even if for a short period of time. Comparing two
different temperature increases will show us a more specific response that we are
looking for so we can better prepare for how these eelgrass shoots might respond in
their natural environment of the Salish Seas with real weather patterns.
Methods
1. Prepare 10 tanks for placing our eelgrass inside. Label these tanks 1-10
and randomize which side of the room they will start on.
2. Collect 20 9” tall tubs to put in the tanks. Label each tub on the outside so
that 10 tubs are A and 10 tubs are B. Randomize which letter tub will be one which
side of the room. Place one A tub and one B tub in each tank.
3. Place one bubbler above each tank and split the tube so that it can reach
into each tub within the tank. Duct tape the tube to the side of the inside of the tub.
4. Make tags for each shoot containing the tank number (1-10), tub letter (A
or B), location by first letter (P or S), shoot letter (Y or Z) and whether it will be
spiked or unspiked (S or U) (example: 5APYS). Print on water proof paper and hole
punch. Tie tags onto string.
5. Collect 80 rocks to attach to the rhizomes of the eelgrass shoots.
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6. Collect the eelgrass - 60 plants from the two locations; Padilla Bay, Ship
Harbor. Although only 40 from each location will be needed, we have extras just in
case something goes wrong. To do this process, we will visit these locations and
carefully uproot the shoots to place into two different buckets (one per location).
Bring these shoots back to the lab to prepare.
7. Place our eelgrass shoots in a tank with bubble snails for about three hours
to eat off most of the epiphytes. Wipe off any excess epiphytes before collecting
them in buckets.
8. Prepare the 2 treatments:
- Ambient Control Tanks (5)
Tanks 1, 5, 6, 8 and 9 (randomized dependent on plumbing)
Water flowing in from Friday Harbor
Each tank contains 2 tubs
Both locations (2 shoots from each location) in each tub
- Warmed Control Tanks (5)
Tanks 2, 3, 4, 7 and 10 (randomized dependent on plumbing)
Air temperature warmed, water not flowing
Each tank contains 2 tubs
Both locations (2 shoots from each location) in each tub
9. Cut the rhizomes of each shoot (80 total) to 4 cm.
10. Tie the tags onto the rhizomes of the shoots and tie around rocks. Each
shoot should have the appropriate tag to its location and a rock to help weigh it
down.
11. Measure the initial shoot length (cm), sheath length (cm), sheath width
(mm), and # of leaves for each shoot. For each leaf on the shoot, measure the total
Gaultier, 9
length (cm) and decay percentage (0%, 1%, 10%, 20%, 50% or 100%) based on the
wasting index chart. Record all of this data in the lab notebook measuring chart.
Prick all of the Y shoots at the end of the sheath length.
12. Place the shoots in the tubs according to their tag. Four shoots total
should be in each tub: 2 from each location, and eight per tank.
13. Check temperature and light of each tub every day between 8:30-11:30
am and 5:30-7:30 pm. For temperature: hold thermometer in the tub for 10 seconds
and let stabilize. For light: hold the knob above the water in the middle of the tub
and let stabilize. Record measurements on “Temp Check Sheet” in lab notebook.
Take notes of process and any abnormalities throughout the experiment in the lab
notebook.
14. After six days, Fill 9 5-gallon buckets with water to let sit over night in the
lab. This will let the water reach the same air temperature as the stationary tanked
tubs.
15. The next day, examine (collect and measure) the pricked “Y” eelgrass
shoot from both locations per tub and record shoot length (cm), sheath length (cm),
sheath width (mm), # of new leaves. On each leaf measure the new growth and the
decay percentage.
16. Place all shoot back in their correct tub based on their tag.
17. Replace the water in each tub to clean them out. For the circulating
tanks, refill the tubs with water pumped in from Friday Harbor. For the stationary
tanks, refill them with water from the buckets that have been sitting over night to
reach the same air temperature as they are in the tubs.
Gaultier, 10
19. After week 2, Measure and record for all “Y” and “Z” shoots (shoot length
(cm), sheath length (cm), sheath width (mm), # of new leaves, growth (cm) on each
leaf and decay percentage).
20. Prick all “Z” shoots after measuring them.
21. Place all shoots back in their correct tubs based on their tag.
22. Starting at 10:30 am, place aquarium heaters into tubs 1B, 2A, 5A, 8B,
and 9B. Spike the eelgrass tub water to 30 C for 13 hours in these five tubs. (We
noticed the temperature was not increasing as we liked so we took the tubs out of
their tanks to place on boards above their tank. We did this at hour 6 which is when
we really saw temperature increases).
23. Record temperatures of each tub (even unspiked ones) every hour of the
spike starting at 10:30 am.
24. At hour 13, turn off and take out the aquarium heaters. Put the tubs back
into their correct tanks.
25. The next day, starting at 1:15 pm, place aquarium heaters into tubs 3A,
4A, 6B, 7B and 10A. Take the tubs out of their tanks to sit on boards above their
tank. Spike the eelgrass tub water to 30 C for 6 hours in these five tubs.
26. Record temperatures of each tub (even unspiked ones) every hour of the
spike starting at 1:15 pm.
27. At hour 6, turn off and take out the aquarium heaters. Put the tubs back
into their correct tanks.
28. After 5 days, Fill 9 5 gallon buckets with water to let sit over night in the
lab. This will let the water reach the same air temperature as the stationary tanked
tubs.
Gaultier, 11
29. The next day, measure and record all of the “Y” eelgrass shoots (shoot
length (cm), sheath length (cm), sheath width (mm), # of new leaves, growth (cm)
on each leaf and decay percentage).
30. Replace the water in each tub to clean them out. For the circulating
tanks, refill the tubs with water pumped in from Friday Harbor. For the stationary
tanks, refill them with water from the buckets that have been sitting over night to
reach the same air temperature as they are in the tubs. While cleaning out the
tubs, scrub off the diatoms that were growing on the side, especially in the
circulating tanks.
31. The next day, measure and record all of the “Z” eelgrass shoots (shoot
length (cm), sheath length (cm), sheath width (mm), # of new leaves, growth (cm)
on each leaf and decay percentage).
32. After 5 days, Measure and record all of the “Y” and “Z” eelgrass shoots
(shoot length (cm), sheath length (cm), sheath width (mm), # of new leaves, growth
(cm) on each leaf and decay percentage).
33. Take down experiment and clean tanks. Dispose of eelgrass.
Statistical AnalysisWe are running a 3-way ANOVA and a split plot.
The response variables we are running statistical analysis on are shoot
length, sheath length, sheath width, new growth for the leaves, and decay
percentage. Our explanatory variables are temperature, acclimated and
unacclimated treatment, location, and spike (short term temperature increase) or
no spike. These last variables are the fixed variables.
We are using the 3-way ANOVA to compare Location (Padilla Bay - warm
location, and Ship Harbor - cold location), Spiked (yes/no), and acclimated (yes/no).
Gaultier, 12
We used a split plot because we have two tubs within one tank.
The random effects are the tanks, tubs, repeatedly measuring shoots.
Functions:
aov()
summary()
Citing R: (R Core Team, 2016)
Core Team (2016). R: A language and environment for statistical computing.
R Foundation for Statistical Computing, Vienna, Austria. URL.https://www.R-
project.org/.
ResultsOur analysis of the response of eelgrass in a gradual temperature increase
showed us that Padilla Bay took a longer period of time to decline in shoot length
(cm) than Ship Harbor. The general trend of Ship Harbor shoot length (cm) shows us
that after week two, the growth began to decline.
Both of the Ship Harbor warmed tanks responded
worse than the cool shoots. The warmed
treatment eelgrass shoots lost about 7-12 cm of
growth since our initial measurements while the
cool treatment eelgrass shoots only lost about 1
or 2 cm since the initial measurements (Figure
2a). In contrast, Padilla Bay eelgrass shoots did
not decline nearly as much as the Ship Harbor
eelgrass shoots. The warmed treatment eelgrass shoots declined the most as well,
but only by about 5 cm since the initial measurements. The cool treatment eelgrass
Gaultier, 13
shoots from Padilla Bay varied a bit between
whether or
not the short
term
temperature increase was put in effect on them.
The cool treatment with the short term
temperature increase grew about 3 cm while
the cool treatment without the short term
temperature increase lost about 3 cm since the
initial measurements (Figure 2b).
The decay of Ship Harbor eelgrass
shoots also trended toward more percentage
than
Padilla
Bay
eelgrass shoots. In the warmed treatment of
Ship Harbor eelgrass shoots, the decay
percentage increased by 30% (Figure 3a). The
warmed treatments of the Padilla Bay eelgrass shoots only increased decay by
about 12% (Figure 3b). The cool treatment eelgrass shoots for both location did not
increase decay by nearly as much. For Ship Harbor, the cool treatment eelgrass
Gaultier, 14
with a short term temperature increase
decayed by 15% at the most while the Ship
Harbor cool treatment without a short term
temperature increase decayed by 5% at the
most. Padilla Bay eelgrass shoots also varied a bit here. The cool treatment eelgrass
shoots with the short term temperature increase seemed to decline in decay,
meaning it started at 25% decayed and ended the experiment with about 20%
decay. The cool treatment without the short term temperature increase increased
only by 5% from the beginning of the
experiment to the end.
The
final analysis of eelgrass response on increasing
water temperature we looked at was the new
growth (cm). The Ship Harbor eelgrass shoots
grew much more than the Padilla Bay eelgrass
shoots. The warm treatment shoots from Ship
Harbor without a short term temperature
increase
seemed to
grow the most,
increasing by
almost 45 cm.
All of the other treatment eelgrass shoots from
Ship Harbor only grew about 19 to 21 cm
(Figure 4a). Padilla Bay eelgrass grew about the
Figure 4a. The total new growth (cm) of Ship Harbor eelgrass
shoots over a period of a month.
Gaultier, 15
same with an exception of the warm treatment
without the short term temperature increase. All
of the Padilla Bay eelgrass shoot treatments
grew about 15 to 25 cm with an exception of the
cool treatment without the short term temperature increase which grew 30 cm
(Figure 4b).
Discussion
Padilla Bay and Ship Harbor took different amounts of time to respond
negatively to gradual temperature increases in the water. We noticed that overall,
Padilla Bay eelgrass shoots were more susceptible to changes in the water
temperature than Ship Harbor eelgrass shoots were because Padilla Bay shoots took
a week longer to begin declining (Figure 2a). These results go in hand with real life
temperatures at these two locations. Padilla Bay receives much higher temperature
fluctuations throughout the year with temperature differences from 3 C in the
winter to 23 C in the
summer. In addition,
temperature
increases of more
than 10 C happen
for about half a
month in the
summer time,
putting the eelgrass
through a bigger stress of
temperature difference for a Figure 5. Padilla Bay and Friday Harbor
temperatures from Novemer 2015 to October 2016.
Gaultier, 16
longer period of time. Ship Harbor on the other hand, only changes from about 8 C
in the winter to 14 C in the summer throughout the year. In the summer, the short
term temperature increases happen for only a week with about a 3 C temperature
increase instead (Figure 5.). While Padilla Bay is having enormous temperature
increase for a longer period of time, Ship Harbor is not as used to large temperature
increases and especially not for a long period of time.
Eelgrass from Padilla Bay reacts better, with less decay, growth stunt and
stop of leaf growth, than Ship Harbor Eelgrass shoots because it is more
accustomed to stressful temperature conditions. Ship Harbor consisted of a faster
decaying response throughout the shoots in the tubs that were going through
gradual temperature increase of 14 C to 19 C because it wasn’t used to reaching
higher temperatures for such a long period of time. The spike of 30 C for 6 hours did
not affect the Ship Harbor shoots as much as the gradual increase because they are
somewhat used to short period temperature increases. The new growth increase on
the warm treatment Ship Harbor eelgrass shoots is a possible response to stress as
well. The increase water temperature could potentially have stressed the eelgrass
to a point of wanting to grow because it was decaying so much.
We thought that Padilla Bay would do better because of the temperature they
are accustomed to in their natural environment. We also thought that acclimated
tubbed eelgrass would do better because they get a gradual increase from 14 C to
19 C before being spiked to 30 C which made for less of a shock in temperature.
This was not the case. We noticed most of the shoots that were acclimated had a
higher mean decaying percent and a decrease in shoot length. This would most
likely be because it added stress because they were “spiked” twice instead of once.
Our responses show us that eelgrass cannot withstand long period of temperature
Gaultier, 17
increases. When thinking about restoration transplantation, we must keep the donor
location in mind. The eelgrass shoots from a colder location responded worse in a
warm location, suggesting to us that eelgrass prefer a similar temperature
environment to live in when moving.
Acknowledgements
I would like to thank the University of Washington, Friday Harbor Labs for
hosting the Eelgrass research class and allowing us to conduct our experiments
here. Sylvia Yang, for teaching the class and sharing all of her knowledge, helping
us through all the ups and down and of course, giving us an incredible amount of
support. Will King, for putting so much dedication into our projects and helping us
abundantly with coding and creating our statistical analyses. The entire FHL 470
eelgrass research class for supporting each other and sharing knowledge
throughout the course. For all of the love and support from my parents, advisors
and close friends for keeping me focused. Lastly, of course for the amazing
communication, cooperation and dedication from my team mates Joanna Luse and
Malise Yun. They were the best team I could have asked for in this project,
constantly keeping us on task while making this project one of the best experiences.
Works Cited
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2. Lee, Kun-Seop, Sang Rul Park, and Young Kyun Kim. "Effects of Irradiance, Temperature, and Nutrients on Growth Dynamics of Seagrasses: A Review." Journal of experimental marine biology and ecology 350.1–2 (2007): 144-75. Web
Gaultier, 18
3. ”Neckles, HA, Short, Frederick T, and Neckles, Hilary A. ""The Effects of Global Climate Change on Seagrasses."" Aquatic Botany 63.3-4 (1999): 169-96. Web.”
4. Nejrup, Lars Brammer, and Morten Foldager Pedersen. "Effects of Salinity and Water Temperature on the Ecological Performance of Zostera Marina." Aquatic Botany 88.3 (2008): 239-46. Web.
5. NOAA. http://tidesandcurrents.noaa.gov/physocean.html?bdate=20151226&edate=20160126&units=standard&timezone=GMT&id=9449880&interval=6 (2016). Web.
6. Raun, Ane Løvendahl, and Jens Borum. "Combined Impact of Water Column Oxygen and Temperature on Internal Oxygen Status and Growth of Zostera Marina Seedlings and Adult Shoots." Journal of Experimental Marine Biology and Ecology. 441 (2013): 16-22. Web.
7. Seattle Times. http://www.seattletimes.com/seattle-news/weather/the-blob-warms-puget-sounds-waters-hurts-marine-life/. (2015). Web.
8. Thom, Ronald, Susan Southard, and Amy Borde. "Climate-linked Mechanisms Driving Spatial and Temporal Variation in Eelgrass (Zostera Marina L.) Growth and Assemblage Structure in Pacific Northwest Estuaries, U.S.A." Journal of Coastal Research 68 (2014): 1-11. Web.
9. Waycott, Michelle, et al. "Accelerating Loss of Seagrasses Across the Globe Threatens Coastal Ecosystems." Proceedings of the National Academy of Sciences of the United States of America 106.30 (2009): 12377-81. Web.