Remediating the emerging problem of lake calcium decline.

1. AQUATIC OSTEOPOROSIS:
Remediating the emerging problem of lake calcium decline
Isabella O’Brien
Grade 10
Westmount Secondary School
Hamilton, Ontario, Canada

2. BACKGROUND1

3. LAKE CALCIUM DECLINE - A LEGACY OF ACID RAIN
• Lake calcium decline is an emerging environmental issue currently impacting softwater
shield lakes in Canada, North-Eastern United States and in Scandinavia.
• The harmful effects of acid rain were recognized in the 1980s as acid rain lowered lake pH,
upsetting the ecological balance and killing aquatic life.
• These acids, however, also caused the calcium in soil to leach at a rapid pace and it occurred
at a faster rate than it could be replaced by mineral weathering or atmospheric deposits.
• In the late 1980s, aggressive environmental policies were put in place to reduce the harmful
carbon dioxide emissions and these measures succeeded in reducing acid rain.
• Since then, lake pH levels have mostly recovered, however, it has recently been discovered
that lake calcium levels have not been restored and are continuing to decrease, with a steep
decline occurring after 1991 (Jeziorski et al., 2012).
• Other environmental stressors that have contributed to this decline include: [1] increase of
shoreline residential development; [2] forest clearing and regrowth, and [3] climate change
(Hadley, 2012).

4. (a) Before acid rain the weathering of
minerals and atmospheric deposits of
calcium-rich dust (from ocean spray, forest
fires, wind erosion of soils, agriculture,
unpaved roads, etc.) all added to the
available pool of calcium nutrients for both
soil and aquatic requirements.
(b) During the early stages of acid rain, the
acids caused the calcium in soil to leach at
a rapid pace into the surrounding lakes.
The calcium levels in these lakes rose very
quickly, especially in softwater lakes in
shield regions which have thin layers of
soil laying on top of weathering resistant
bedrock.
(c) Eventually, with continued acidic rain, the
available calcium pool in the shield regions
diminished to the point that calcium
leaching is greatly reduced and occurred at
a faster rate than it could be replaced. In
addition, the effects of multiple stressors
have further diminished the calcium
supply. (Smol, 2010)
NATURAL CONDITIONS EARLY STAGES OF ACID DEPOSITION
MULTIPLE STRESSORS LEADING TO
AQUEOUS CALCIUM DECLINE
Figure 1: Calcium Cycle in Forest Ecosystems [Source: USGS,
1999]
Root Uptake
Forest
Floor
Adsorption to Surfaces
Desorption
from Surfaces
Calcium in Rocks
Weathering
Mineral
Soil
Calcium
in
Soil Water
Ca
Ca
Ca
Ca
Ca
Ca
Ca
Ca
Ca
Ca
Exchangeable
Calcium
Ca
CaCa
Ca
CaCa
Ca
Ca
Ca
Rain and Dust
Ca
Ca
Ca
Ca
Ca
Ca
Ca
Ca
Ca
Ca
Ca
Wet Deposition (rain, snow, sleet)
Sulphuric Acid [H2SO4]
Nitric Acid [HNO3]
SO2
NOx
Dry Deposition
(particulates and gases)
Sulphur
Dioxide
[SO2]
NOx
Nitrogen
Oxide
[NOx]
Figure 2: Acid Rain Cycle [Source: Dowdey, 2007]

5. SERIOUS THREAT TO VITAL ZOOPLANKTON & LAKE BIODIVERSITY
• Lake calcium decline is a serious issue for Daphnia pulex which are an important component
of freshwater lakes and very sensitive to declining calcium levels. For Daphnia pulex, lake
calcium decline has meant that their calcium rich exoskeletons are smaller and softer
making them more vulnerable to prey (Riessen et al., 2012).
• Invasive species such as the spiny water flea are hunting the daphnia, allowing population
explosions of Holopedium, plankton competitors of Daphnia pulex (Jeziorski et al., 2015).
• This increased jellification of lakes prevents vital nutrients from being passed up the food
chain to fish stocks and also clogs filtration systems that help the lakes provide drinking
water to residents in the area (Ibid., 2015).
• In laboratory studies, it has been determined that Daphnia pulex are unable to reproduce at
calcium levels below 1.5 mg/L and currently ⅓ of Canadian Shield lakes are below this level
(Ashforth & Yan, 2008).

6. • “Calcium-rich daphniids are some of the
most abundant zooplankton in many lake
systems, and their loss will substantially
affect food webs” (Jeziorski & Yan, 2008: 1377).
• Due to their larger body size, Daphnia pulex
are important herbivores in freshwater
systems as they are able to filter food
particles at a much faster rate and they
graze a wider size and range of algae
compared to other species (Korosi et al., 2012).
• As Daphnia pulex numbers decline, the rate
of softwater lake algae blooms are
increasing and the entire biodiversity of
lakes is changing (Ibid., 2012).
ECOSYSTEM IMPLICATIONS
Photo credits:
1. Reuters/Stringer
2. Paul Herbert
3. Michael Lencioni
4. Isabella O’Brien
5. ontariofishspecies.com
Algae
Daphnia Pulex
Waterfowl
Invertebrate Predators
Fish
Figure 3: Ecosystem Implications [Source: Smol, 2014]

7. REMEDIATION BY RECYCLING
• Current research on lake calcium decline is focused on the extent of the problem and its
implications, rather than on remediation. However, existing research on remediating acidity
(low pH) in lakes and oceans may suggest a way forward.
• Lime treatment of inland waters in Sweden to neutralize acidity (Olem, 1991) and small-scale
oyster shell recycling programs in various U.S. coastal areas to restore oyster beds damaged
by ocean acidification (NOAA MPA Centre, 2015), are suggestive of a possible method for
remediating lake calcium decline.
• Both lime and waste shells are a rich source of calcium carbonate, with waste shells
composed of 95 to 98% calcium carbonate (Hamester, 2012).
• With an estimated six million metric tons of shell waste produced globally each year based
on worldwide statistics of aquaculture and commercial catches of mussels, clams and
oysters and about ½ a million metric tons just in the U.S. and Canada (Food and Agriculture
Organization of the UN, 2013), the potential exists to have this shell waste recycled instead of
being sent to landfill, the disposal of which has become a worldwide issue (Fisheries and Oceans
Canada, 2011; Yan & Chen, 2015).

8. PURPOSE &
HYPOTHESIS2

9. PURPOSE:
• The purpose of this experiment was to determine whether the addition of pulverized
recycled shell waste to calcium-deficient lake water would increase the calcium
concentration and to examine what effect it would have on the survival and reproductive
output of Daphnia pulex exposed to the calcium-augmented waters.
• The information gained from this experiment will hopefully aid in developing a process to
help restore calcium-deficient lakes, which will be beneficial in maintaining Daphnia pulex
populations as well as help protect lake biodiversity, minimize lake algae blooms and divert
shell waste from landfill.
HYPOTHESIS:
It is hypothesized that if calcium carbonate waste shells are introduced to calcium-deficient
lake water, then the absorption of the calcium carbonate will increase lake calcium levels as
well as the survivorship and reproductive capabilities of Daphnia pulex.

10. EXPERIMENTAL
DESIGN and
PROCEDURE3

11. EXPERIMENTAL DESIGN:
• The two trials (3.4 mgCa/L and 1.89 mgCa/L, representing low and critical levels of lake water
calcium, respectively) with differing treatments (0 mg, 10 mg, and 50 mg shell powder
added) were run for 21 days with ten replicates each.
• Each test vessel (250 ml polyethylene terephthalate cups) contained 200 ml of the
appropriate treatment plus .03 ml of algae food source (Nannochloropsis) and was
populated with one juvenile (less than 1 day old) daphnia, as follows:
TRIAL 1
Control = 200 ml lake water @ Ca 3.4 mg/L + 0 mg shell powder + one <1-day old daphnia x 10 replicates
Treatment 1 = 200 ml lake water @ Ca 3.4 mg/L + 10 mg shell powder + one <1-day old daphnia x 10 replicates
Treatment 2 = 200 ml lake water @ Ca 3.4 mg/L + 50 mg shell powder + one <1-day old daphnia x 10 replicates
TRIAL 2
Control = 200 ml diluted lake water @ Ca 1.89 mg/L + 0 mg shell powder + one <1-day old daphnia x 10 replicates
Treatment 1 = 200 ml diluted lake water @ Ca 1.89 mg/L + 10 mg shell powder + one <1-day old daphnia x 10 replicates
Treatment 2 = 200 ml diluted lake water @ Ca 1.89 mg/L + 50 mg shell powder + one <1-day old daphnia x 10 replicates

12. 12
2 Trials of
1 Control and
2 Treatments
TRIAL 1
(Low Calcium Level @ Ca 3.4 mg/L )
TRIAL 2
(Critical Calcium Level @ Ca 1.89 mg/L)
10 Replicates
per Control &
Treatment
per Trial
1 juvenile
Daphnia pulex
< 1-day old
per vessel
Control
+ 0 mg
shell powder
Treatment 1
+ 10 mg
shell powder
Treatment 2
+ 50 mg
shell powder
12 12 12 12 12
Sampling Rate: daily for 21 days – treatments were refreshed every third day
Controls: Light/Dark ratio (18/6 hr), temperature (20 – 22oC), feed (.03 ml algae per day)
Control
+ 0 mg
shell powder
Treatment 1
+ 10 mg
shell powder
Treatment 2
+ 50 mg
shell powder

13. MATERIALS:
QUANTITY MATERIALS USED
1 Coffee grinder
1 Box of wax paper
1 Box of scientific wipes
1 Box of nitrile-free disposable gloves
1 Plastic bucket for collecting lake water
1 Fine mesh water filter (200-micron)
1 Calibration fluids (pH 4.7, 7.0 and 10.0)
1 Digital pH Meter – Accuracy +/- .01
1 Digital scale
1 Wash bottle
1 Metal spoon
1 1 L bottle algae food source (Nannochloropsis)
2 1 cup measuring cups
2 1 large and 1 medium funnel
2 Cool fluorescent lamps
2 Light timers
3 Living Daphnia pulex cultures
3 20 L water storage jugs
4 50 mL beakers
4 1.5 L plastic holding tubs for Daphnia pulex cultures
6 10 L jug containers
9 Blue Mussels (Mytilus edulis – from P.E.I.)
9 Littleneck Clams (Venerupis philippinarum – from B.C.)
9 Malpeque Oysters (Carassostrea Virginia – from B.C.)
9 1 L bottles of spring water
10 1 mg and 10 mg pipettes
20 10 mL vials with lids
50 Litres of deionized water
500 200 mL plastic cups
INDEPENDENT, DEPENDENT & CONTROLLED VARIABLES:
Question
Can using
pulverized calcium
carbonate shells in
calcium –deficient
lake water increase
the calcium
concentration
without being
detrimental to
Daphnia pulex?
Independent Variable
The independent
variable was the test
solutions [Trial 1 and
Trial 2] and the amount
of shell powder added
[the treatments: +0 mg,
+10 mg and +50 mg]
Trial 1- Low calcium
level lake water
@ 3.4 mg/L
Trial 2 - Critical calcium
level lake water
@ 1.89 mg/L
Dependent Variables
• The percentage
increase of calcium
concentration.
• The survivability of
the Daphnia pulex.
• The reproduction
rate of the Daphnia
pulex.
• The number of
broods over a 21
day period.
Controlled Variables
• The amount of
each treatment
(200 ml).
• The amount of
time each baby
daphnia remained
in the solution
(21 days).
• The exposure to
light / dark during
the testing period
(16/8 hours).
• The temperature of
the room where
the solutions were
stored (kept at 20-
22oC).
• The amount of
daphnia algae feed
per day (.03 ml).

14. SET-UP and PROCEDURE:
WATER SAMPLE:
• Water used in this experiment was collected from a long-term monitoring site (Plastic Lake,
Dorset region, Ontario, Canada; 5 10'47" North and 78 49'16" West).
• The site is near the southern edge of the Precambrian Shield and the boundary of the Boreal
eco-zone and was chosen based on its last reported critical calcium level of 1.2 mg/L.
• Test results using a university lab Dionex Ion Chromatography system revealed the actual
calcium level of the sample was 3.4 mg/L (probably due to several factors: rain earlier in the
week, only being able to obtain the water sample near the shore, and time of year).
• The water samples were filtered into clean containers using a 200-micron water filter and
stored in the dark at 5 C until required for preparing the test treatments at which time they
were brought to the test room temperature (20 – 22 C).
° °
°
°

15. DAPHNIA CULTURE:
• Three separate cultures of Daphnia pulex were obtained and reared in spring water. The
daphnia cultures were maintained for 60 days prior to use in the experimental trials.
MEDIA PREPARATION:
• Two trials were run for this experiment: [1] low calcium level lake water at 3.4 mg/L and
[2] critical calcium level lake water (lake water diluted with deionized water) to bring the
calcium level closer to the Daphnia pulex calcium threshold of 1.5 mg/L. The Ion
Chromatography test result for the prepared diluted batch returned a calcium reading of
1.89 mg/L.
SHELL POWDER PREPARATION:
• The shells of mussels, clams, and oysters were used to prepare the shell powder. The
mollusks were shucked, cleaned of all organic material and heat treated to remove any
bacteria. Each shell type was ground separately to a fine powder, sifted using a fine mesh
sieve and stored separately. For the purposes of testing, 38 grams of each shell powder
type was measured and combined in a single container for testing use.

16. TESTING:
• During the 21 day testing period, each test cup was examined daily for daphnia
survivorship and reproduction.
• Typical observations included daphnia viability, the number of broods produced, and how
many offspring per brood were present.
• All offspring were counted and removed each day.
• The temperature (20 – 22 C), light exposure (16 hours light / 8 hours dark), and length of
time in solution (21 days) were held constant throughout the experiment.
• Additionally, the pH level was measured each day for every treatment, using a calibrated
pH meter.
• To prevent stagnation and bacteria buildup in the test cups, daphnia were transferred via
pipette to a new unused cup containing a fresh treatment solution every three days.
°

17. Image 1: Plastic Lake, Dorset, Ontario
Images 2 & 3: Collecting & filtering lake water Image 4: Preparing samples for calcium testing Images 5 & 6: Shell grinding & measuring shell powder treatments
Images 7, 8 & 9: Daphnia culture tanks; harvesting adult daphnia with eggs; adult daphnia with eggs Image 10: Basement testing lab set-up
Photos: I. O’Brien / A. Ceccato
1
2 3 4 5 6
7 8 9 10

18. RESULTS4

19. CALCIUM LEVEL
Trial 1 – Low calcium level @ 3.4 mg/L
The calcium level results for Treatment 1 and Treatment 2
significantly differed from the control (p=0.043 and p=0.01
respectively) but the two treatments did not differ significantly from
each other. This result indicates that the shell powder had a direct
effect on increasing calcium levels in the water, but this effect was
not dose dependent.
In Treatment 1, the calcium level increased from 3.4 mg/L to 13.2
mg/L, an increase of 288% and in Treatment 2 the calcium level
increased from 1.89 to 12.92 mg/L, an increase of 280%.
Trial 2 - Critical calcium level @ 1.89 mg/L
Treatment 2 significantly differed from the control (p=0.01), but not
from Treatment 1 (p=0.54) and Treatment 1 and 2 did not differ
significantly from each other. This result indicates that the shell
powder had an effect on increasing calcium levels in the lake water,
but this effect was more significant when the higher level of shell
powder was added.
In Treatment 1, the calcium level increased from 1.89 mg/L to 14.18
mg/L, an increase of 650% and in Treatment 2 the calcium level
increased from 1.89 mg/L to 13.33 mg/L, an increase of 605%.
3.40 3.40 3.40 3.40 3.40
4.31
8.88
11.33
13.20
8.83
12.83
11.51
12.92
0
2
4
6
8
10
12
14
16
Day 1 Day 2 Day 3 Day 4
CALCIUMLEVEL(mg/L)
DAY OF TRIAL
Calcium Level Trend Over Renewal Period
[Trial 1- Low Calcium Level @ 3.4 mg/L]
Control
Treatment 1
Treatment 2
1.89 1.89 1.89 1.89
3.57
7.21
9.43
14.18
1.89
7.48
11.90
13.03 13.33
0
2
4
6
8
10
12
14
16
Day 1 Day 2 Day 3 Day 4
CALCIUMLEVEL(mg/L)
DAY OF TRIAL
Calcium Level Trend Over Renewal Period
[Trial 2 - Critical Level Calcium @ 1.89 mg/L]
Control
Treatment 1
Treatment 2

20. SURVIVORSHIP
For both trials, Treatment 1 and Treatment 2
significantly differed from the control treatment
with (p<0.001), however, Treatment 1 and
Treatment 2 did not differ significantly from each
other (p=1.0). This result indicates that the shell
powder had a direct effect on increasing the
survivorship of the daphnia, but this effect was
not dose dependent.
For both trials, the treatments that had shell
powder added resulted in 100% survivorship. For
the low calcium level control, 80% of the daphnia
survived over a 21 day period and for the critical
calcium level control, only 40% survived.
0
2
4
6
8
10
12
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
NUMBEROFLIVINGDAPHNIAREPLICATES
DAY OF TRIAL
Survivorship Over 21 Day Trial Period
[Trial 2 - Critical Calcium Level @ 1.89 mg/L]
Control
Treatment 1
Treatment 2
0
2
4
6
8
10
12
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
NUMBEROFLIVINGDAPHNIAREPLICATES
DAY OF TRIAL
Survivorship Over 21 Day Trial Period
[Trial 1 - Low Calcium Level @ 3.4 mg/L]
Control
Treatment 1
Treatment 2

21. REPRODUCTION
Time to First Brood:
For both Treatment 1 and 2 in Trial 1, there was no
significant difference in the number of days before
the first broods were produced and the control
(p>0.05). Therefore the addition of shell powder,
regardless of the dosage, had no effect on the number
of days to first brood in the low level calcium trial.
For both treatments in Trial 2, the average number of
days before the first brood appears was significantly
different from the control (p=0.020 and p=0.011
respectively) but the two treatments did not differ
significantly from each other. This indicates that the
added shell powder had a direct effect on decreasing
the number of days to first brood in critical calcium
level water, but was not dose dependent.
12.6
15.2
11.8
12.2
11.4
11.9
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Trial 1 Trial 2
AVERAGENUMBEROFDAYS
TRIALS
Average Number of Days Before First Brood
Control
Treatment 1
Treatment 2

22. REPRODUCTION (continued)
Mean Number of Broods Produced & Offspring Born:
In Trial 1, the mean for both the number of broods
produced and the number of offspring (p=0.193 and
p=0.060 respectively) was not significantly different
between groups. However, in Trial 2 the mean for both the
number of broods and the number offspring in both
Treatments 1 and 2, was significantly different from the
control (p=0.21, p=0.004, and p=0.036, p=0.005
respectively). These results indicate that the added shell
powder had a significant effect on increasing the
reproductive output, but only in Trial 2 and this effect was
not dose dependent.
In Trial 2, the mean number of broods for Treatment 1 was
125% greater than the control and 158% greater in
Treatment 2. Also in Trial 2, the mean number of offspring
for Treatment 1 was 143% greater than the control and
195% greater in Treatment 2.
2.3
1.2
3.5
2.7
3.2 3.1
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Trial 1 Trial 2
MEANNUMBEROFBROODS
TRIALS
Mean Number of Broods Produced
Over 21 Day Trial Period
Control
Treatment 1
Treatment 2
7.9
4.0
15.3
9.710.0
11.8
0
2
4
6
8
10
12
14
16
18
20
Trial 1 Trial 2
MEANNUMBEROFOFFSPRING
TRIALS
Mean Number of Offspring Born
Over 21 Day Trial Period
Control
Treatment 1
Treatment 2

23. OBSERVATIONS:
• The juvenile daphnia in the treatments with shell powder added, visually grew larger than the daphnia in
treatments with no shell powder added.
• During the testing period, the pH of the treatments was measured. The pH levels increased significantly in
all test cups after the shell powder was added to the lake water. In both treatments, the pH level
significantly differed from the controls. However, the pH level in Treatment 1 (10 mg) and Treatment 2
(50 mg) did not differ significantly from each other.
SOURCES OF ERROR:
• The pH meter used had an accuracy of +/- 0.1 which may have affected the readings.
• With regard to the reproduction and viability of the daphnia, it should be noted that these results only
reflect controlled lab conditions and in a real world scenario, the daphnia would have been subjected to
other stressors which would have altered the results in terms of viability, reproduction, brood size, etc.
• The process of transferring the daphnia, either at the less than one-day old stage or during each
treatment solution refresh period is also another possible source of error, as the transferring process may
have caused a level of stress in the Daphnia leading to either death or impacting the number of broods
and offspring.

24. CONCLUSION &
DISCUSSION5

25. CONCLUSION
• The experiment’s hypothesis was supported when the addition of the shell powder to calcium-deficient
lake water increased the calcium levels as well as increased daphnia survivorship and the number of
broods and offspring. The results were most significant in the critical calcium level lake water.
• As a result, the addition of pulverized recycled shell waste to the independent variable [the treatments]
has a direct and significant effect on the dependent variables [the calcium concentration and daphnia
survival and reproduction].
• The results clearly show that the addition of shell powder to increase calcium levels can be effective both
for remediation of critical lake calcium levels, which proved to be very beneficial for daphnia survivorship
and reproduction and it can also be used as a preventative measure in low calcium level lakes to prevent
lake calcium levels from decreasing any further and to maintain existing daphnia populations.
• The decline of Daphnia pulex populations, the increase of lake algae blooms and the appearance of
invasive species are all consequences of this emerging environmental problem which is causing
widespread transformations of aquatic food webs in softwater shield lakes in North America and in other
acid-sensitive regions of the globe.
• This experiment identifies a method to remediate lake calcium decline and has the potential to be
beneficial in maintaining Daphnia pulex populations, which will protect lake biodiversity and help mitigate
algae blooms while at the same time contribute toward addressing the global issue of shell waste disposal.

26. DISCUSSION
• The inspiration for this project came from my previous work on ocean acidification where waste shells in pulverized form were used to
buffer ocean acidity. The positive results of my previous project inspired me to find additional ways in which waste shells could be used
given that waste shells are a readily available and abundant reusable resource.
• Globally, the disposal of the millions of metric tons of waste shells has become an increasing problem just due to the sheer volume and
weight of waste. Recycling of these shells from large volume producers such as canneries, processors, and even seafood restaurants is
a potentially highly cost-effective solution.
• The disposal costs of the waste shells are high because it is done by the ton. If a recycling program is put in place for large volume
producers, the cost of recycling and processing the waste shells could be recovered by selling the pulverized shells for other uses as
well such as construction, soil treatment, pharmaceuticals, etc. Processing costs could be reduced by allowing the shells to age in the
sun for about a year in order to dry and sanitize them and also by using renewable energy for the shell grinding process.
• Furthermore, based on my previous research into ocean acidification, the shell powder could also be used in marine protected areas
to increase pH levels and mitigate the effects of ocean acidification.
• In terms of the application of the shell powder to the lakes, the costs would be dependent on the method of application. For accessible
lakes, the shell powder could be applied by boat or on the watershed and in winter, it could be applied on the ice. Where there is
limited access to a lake, aerial methods would have to be used to apply the shell powder in the same manner as limestone was applied
to lakes in Sweden to combat lake acidity.
• The dosage of shell powder would need to be stoichiometrically calculated taking into consideration the volume of the lake, the
current pH, and calcium level, the desired calcium level, the flow through rate, etc. Also, constant monitoring of the lake calcium level
would be required to determine if and when additional applications of shell powder would be required.
• Further investigation could be conducted in using this method as a watershed soil treatment to see if leaching from the soil to the lake,
instead of direct application to the lake, would be another approach to not only increase lake calcium levels but also restore soil
calcium levels which have been having a damaging effect on tree growth.

27. ACKNOWLEDGEMENTS
Thank you to the following for their assistance with this project:
Rice Engineering for donating test supplies (laboratory gloves, wash bottle, precision tissue wipes).
Dr. Patty Gillis from the Canada Centre for Inland Waters for providing me with a digital scale, calibration fluid, water jugs and filters and deionized water.
Prof. Merrin Macrae and Mr. Vito Lam at the University of Waterloo for providing access to the Dionex Ion Chromatography system for calcium testing of the water samples.
Prof. Norman Yan (York University) Mr. Andrew Jeziorski (Queen’s University) and Mr. Dennis Poirier (Ministry of the Environment) for answering questions and providing access to their research papers.
Ms. Susan Samuel-Herter for help with the statistical analysis.
Mr. Dan Bowman, and his son Mr. Jordan Bowman, for reviewing the project and providing helpful comments and advice for improvement.
Ms. Angela Ceccato and Mr. Robert O’Brien, my parents, for their support and encouragement.
REFERENCES
Ashforth, D. and Yan, N. (2008). ‘The interactive effects of calcium concentration and temperature on the survival and reproduction of Daphnia pulex at high and low food concentrations’, Limnology and Oceanography,
53, doi: 10.4319/lo.2008.53.2.0420.
Dowdey, S. (2007.) How Acid Rain Works. Retrieved 15 August 2015 from http://science. Howstuffworks.com/nature/climate-weather/atmospheric/acid-rain.htm.
Fisheries and Oceans Canada. (2014). Introduction of Commercial Shell Crushing Technology to the BC Oyster Aquaculture Industry. Retrieved 25 September 2015 from www.dfo-mpo.gc.ca/aquaculture/sustainable-
durable/rapports-reports/2011-12/P17-eng.htm.
Food and Agriculture Organization of the United Nations. (2016). Global Production Statistics 1950-2013. Retrieved 14 February 2015 from www.fao.org/figis/servlet/TabLandArea?tn_ds=Production
&tb_mode=TABLE&tb_act=SELECT&tb_grp=country.
Hadley, K. (2012). A Multi-Proxy Investigation of Ecological Changes Due to Multiple Anthropogenic Stressors in Muskoka-Haliburton, Ontario, Canada. Queen’s University Ph.D. Dissertation, 28 September 2012. Retrieved
28 July 2016 from http://hdl.handle.net/1974/7547.
Hamester, M.R.R., et al. (2012). ‘Characterization of calcium carbonate obtained from oyster and mussel shells and incorporation in polypropylene’. Materials Research, (São Carlos. Impresso), v. 15, p.204-208.
Jeziorski, A., and Yan, N. (2008). ‘The widespread threat of calcium decline in fresh waters’. Science, 322(5902):1374–1377.
Jeziorski, A., et al. (2012). ‘Changes since the onset of acid deposition among calcium-sensitive caducean taxa with softwater lakes of Ontario, Canada’. Journal of Paleolimnology, 48: 323-337.
Jeziorski, A., et al. (2015). ‘The jellification of north temperate lakes’. Proceedings of the Royal Society B, 41.282: 20142449.
Korosi, J.B., et al (2010). Anomalous rise in algal production linked to lake water calcium decline through food web interactions. DOI: 10.1098/rspb.2011.1411, 28 September 2011.
NOAA MPA Centre. (2015) Climate Change Issue Profile: Ocean Acidification. Retrieved 16 August 2015 from http://marineprotectedareas.noaa.gov/sciencestewardship/climatechangeimpacts/ocean-acidification.pdf.
Olem, H. (1991). Liming Acidified Surface Waters. Lewis Publications: Boca Raton, Florida.
Riessen, H.P., et al. (2012). ‘Changes in water chemistry can disable plankton prey defenses’. Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1209938109.
Smol, J. (2010). ‘Multiple Stressors in Freshwater Ecosystems’, Freshwater Biology, Volume 55, Issue Supplement S1, pages 43–59, January 2010.
Smol, J. (2014). Exploring Our Past to Protect Our Future. Lecture, March 2014. Retrieved 14 August 2015 from https://www.trentu.ca/aquaticscience documents/TrentSchindlerLecture.
United States Geological Society, (1999), Soil-Calcium Depletion Linked to Acid Rain and Forest Growth in the Eastern United States. Retrieved 15 September 2015 from
http://ny.water.usgs.gov/pubs/wri/wri984267/WRIR98-4267.pdf.
Yan, N. and Chen, X. (2015). ‘Sustainability: Don’t waste seafood waste’, Nature, 10 August 2015. Retrieved 16 March 2015 from http://www.nature.com/news/sustainability-don-t-waste-seafood-waste-1.18149.