senior research presentation final
TRANSCRIPT
The Effect of Fertilizer Runoff Conditions on the Development
of Danio rerio EmbryosErica Gillespie
Senior Research Advisor: Dr. GibbsStetson University
What is Eutrophication?
http://www.ecodetail.net.au/wp-content/uploads/2012/07/eutrophication1.jpg
Danio rerio (Zebrafish) Transparent embryos Short developmental period
(72 hours) Development of Zebrafish is
well-known. Near completion of of the zebrafish genome allows scientists to identify end points of toxicity (Hill et al., 2005)
Freshwater Fish are less tolerant of nitrite toxicity than marine animals
http://fc06.deviantart.net/fs39/i/2008/348/9/c/Zebra_Fish_Embryo_by_IbieMonstah.jpg
Environmental Protection Agency (EPA) Guidelines
Natural levels of nitrate in surface waters seldom exceed 0.1 mg/l of N, but waters influenced by human activity normally contain up to 5 mg/l of N (Chapman, 1992)
National drinking water standards are 10 µg N/L of nitratesAfter reviewing existing nutrient criterions directed by the
Everglades Forever Act (Payne et al., 2012), The EPA and the Florida Department of Environmental Protection (FDEP) set a total phosphorous (TP) and total nitrogen (TN) limit of 10 µg/L. areas of Lake Okeechobee exceed 92 µg/L (Payne, 2012).
Studies show nitrate concentrations of 10 mg NO3 – N/L (USA federal maximum level for drinking water) can affect sensitive aquatic animals when exposed long term (Camargo &Alonso, 2006)
What are the Implications?
http://inhabitat.com/aquatic-dead-zones-produce-greenhouse-gas-300x-more-potent-than-co2/
Implications for Biota Study conducted by Thomas &
Rahman (2010) focused on testicular development and sperm production in the northern Gulf.
Due to low oxygen levels production of sperm declined, the fish began to have smaller lumens, and even experience a 50% decrease in testicular growth.
Impact population abundance if they cannot reproduce enough to replenish the population http://www.chartingnature.com/img/fish-
illustration-prints/atlantic-croaker-2085.jpg
Nitrogen in Reclaimed WaterReported by Institute of Food and Agricultural Sciences
http://edis.ifas.ufl.edu/ae479
Deland Water Utilities Water Quality Report 2011 & 2013
http://www.deland.org/Pages/DeLandFL_PSUtilities/index
HypothesisZebrafish embryos exposed to fertilizer runoff
conditions would have a dose-dependent response to fertilizer that will include retarded growth.
Methods
Control15 ml Spring Water
24 Hour Exposure
12.5x 25x
50x 100x0.001
g/L
150x0.0015
g/L
Control15 ml Spring Water
48 Hour Exposure
12.5x 25x
50x 100x0.001
g/L
150x0.0015
g/L
24/7 Exposure
20Control15 ml Spring Water
2000x=0.02
g/L
4000x = 0.04
g/L
5000x=0.05
g/L
10000x=0.1 g/L
Methods
ResultsThere was no effect of
fertilizer concentration on zebrafish mortality
http://s0ftpedia.net/files/zebrafish%20embryo&id=mix
Figure 1. Average Head Width (mm)
There was not a dose-dependent change in head width after exposure to fertilizer
Head Width T-Test ResultsControl vs. 2000x
0.00231Control vs. 4000x
1.88E-09Control vs.5000x
1.85E-09Control vs.10000x
0.448
4000x vs. 5000x 0.4614000x vs. 10000x
0.143
2000x vs. 4000x
0.00644
2000x vs. 5000x
0.00746
2000x vs. 10000x
0.264
5000x vs. 10000x
0.146
Table 1. P Values from T-Test for Head Width (mm) comparing the control to upper solution
concentrations
Table 2. P Values from T-Test for Head Width (mm) comparing 2000x to upper solution
concentrations
Table 3. P Values from T-Test for Head Width (mm) comparing upper solution
concentrations
Figure 2. Average total length (mm) from tip of head to end of tail.
There was a significant threshold response of body length to fertilizer concentration
Total Length T-Test Results
Table 4. P Values from T-Test for Total Length (mm) comparing the control to solution
concentration
5000x vs 10000x
0.421
4000x vs 5000x 0.1424000x vs 10000x 0.202
Table 5. P Values from T-Test for Total Length (mm) comparing upper solution
concentrations
Figure 3. Average body width (mm) from widest point.
There was a significant threshold response of body width to fertilizer concentration
Body Width T-Test Results
4000x vs. 5000x
0.387
4000x vs. 10000x
0.4665000x vs 10000x
0.356
Control vs. 2000x
0.00242
Control vs. 4000x
1.01E-07
Control vs. 5000x
3.94E-08
Control vs. 10000x
1.8E-07
Table 6. P Values from T-Test for Body Width (mm) comparing the control to solution
concentrations
Table 7. P Values from T-Test for Body Width (mm) comparing upper solution
concentrations
ConclusionsThere was no statistically significant difference in
zebrafish mortality exposed to varying fertilizer concentrations
There were no dose-dependent responses to the fertilizer, however, there were strong threshold responses (reductions) of body length and width starting at 4000x.
Concentrations used here exceeded EPA safe levels but with additional research can compare to local values in reclaimed water/irrigation.
Future ResearchWider ranges to determine a specific threshold.Have adult zebrafish spawn in fertilizer conditions so
embryos continuously exposed to run-off conditions. Would reproducing in these conditions cause greater growth deformities?
Further morphological measurements (head density, top of head to bottom, etc.)
These measurements focused on external growth, possible internal issues with development?
Replicate Local Values/ Reclaimed water
AcknowledgementsStetson UniversityBiology DepartmentDr. GibbsFriends and Family
ReferencesCamargo J. & Alonso A. (2006). Ecological and
toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment. Environment International. 32(6): 831-849.
Chapman, D. 1992. Water quality assessments. Chapman and Hall, London, UK.
Payne G., Weaver K., Xue S. (2012). Chapter 2C: Status of Phosphorous and Nitrogen in the Everglades Protection Area. 2012 South Florida Environmental Report. 1 (2): 2C-1 – 2C-30).
Questions?