1. Comparison of Fish Mercury
Concentrations among Sample
Preparation Methods
Michael Persson, SUNY-ESF
Dr. Charley Driscoll, Mario Montesdeoca, Amy Shaw & Mariah Taylor, Syracuse University
1
2. Overview
• Background
• Objectives
• Previous literature to compare standard filets and plugs
• Comparison between DEC filets and plugs
• Correction between DEC filets and plugs
• Conclusion & the Future
2
3. Objectives of this Study
1) Establish similarities between the plug and standard filet
2) Identify trends between DEC filet and plug
• Length and weight across all samples
3) Evaluate the relationship method between DEC filet and plug
3
5. 1) Plugs
• Small amount of muscle tissue obtained from below the dorsal fin using
biopsy punch
5
Biopunch used to retrieve and recover muscle tissue
Two white circles represent approximate
sample location for plug
6. 2) Standard filets
• Left side filet of muscle tissue only
3) DEC filets
• Left side filet of muscle tissue including rib cage and skin (no scales)
6
Lines represent locations of incisions to be made to obtain a standard filet
sample. Numbers represent the recommended order for making incisions.
8. Murphy et al. 2009
Data source: 2008 – 2009 Baseline Monitoring Program (BLM); non-detects reported at ½ the MDL
Notes: all ages and sexes combined. Regression on log transformed data. Data is log base 10
8
Scatter plot of fillet vs plug mercury concentrations (ppm wet) in fish collected from Onondaga Lake
10. Objectives of this Study
1) Establish similarities between the plug and standard filet
2) Identify trends between DEC filet and plug
• Length and weight across all samples
3) Evaluate the relationship method between DEC filet and plug
10
12. -2.6
-2.1
-1.6
-1.1
-0.6
-0.1
0.4
-3 -2 -1 0 1 2 3
Plugln(Hgwetweightinµg/g)
Filet ln(Hg wet weight in µg/g)
All species
n=241
All YP
All RB
All CP
All LT
All LM
All SM
All WY
1 to 1
12
13. y = 0.0003x + 0.341
R² = 0.1873
y = 0.0003x + 0.3985
R² = 0.1847
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
0 1000 2000 3000 4000
[THgwetweight](µg/g)
Weight (g)
All fish sample masses (g) vs. [THg wet weight] (µg/g)
Linear (DEC Filet)
Linear (Plug)
y = 0.0012x + 0.1043
R² = 0.2272
y = 0.0014x + 0.1065
R² = 0.2476
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
0 100 200 300 400 500 600 700 800
[THgwetweight](µg/g)
Length (mm)
All fish sample lengths (mm) vs. [THg wet weight]
(µg/g)
Linear (DEC Filet)
Linear (Plug)
13
14. Objectives of this Study
1) Establish similarities between the plug and standard filet
2) Identify trends between DEC filet and plug
• Length and weight across all samples
3) Evaluate the relationship method between DEC filet and plug
14
16. • Similar to length-standardization
method for mercury concentration
• Plotted all filet and plug values to
gain trend
• Plugged original filet value into the
regression equation
• This value is, “projected DEC filet”
• Evaluated relative percent differences
(RPD) between predicted and actual
filet concentrations
• Fish mass (g) or length (mm) is
plotted against projected DEC filet
(µg/g)
y = 1.1446x + 0.0089
R² = 0.9735
0.0
0.5
1.0
1.5
2.0
2.5
0.0 0.5 1.0 1.5 2.0
Plug[THgwetweight](µg/g)
Filet [THg wet weight] (µg/g)
Filet [THg wet weight (µg/g)] vs. Plug [THg wet weight
(µg/g)]
Linear (Filet vs. Plug)
16
17. y = 0.0012x + 0.1043
R² = 0.2272
y = 0.0014x + 0.1065
R² = 0.2476
y = 0.0014x + 0.1105
R² = 0.2272
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0 100 200 300 400 500 600 700 800
[THgwetweight](µg/g)
Length (mm)
All fish sample lengths (mm) vs. [THg wet weight]
(µg/g)
Linear (DEC Filet)
Linear (Plug)
Linear (Predicted DEC
Filet)
y = 0.0003x + 0.341
R² = 0.1873
y = 0.0003x + 0.3985
R² = 0.1847
y = 0.0003x + 0.3814
R² = 0.1873
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0 1000 2000 3000 4000
[THgwetweight](µg/g)
Weight (g)
All fish sample masses (g) vs. [THg wet weight] (µg/g)
Linear (DEC Filet)
Linear (Plug)
Linear (Predicted DEC
Filet)
17
Linear (Projected
DEC Filet)
Linear (Projected
DEC Filet)
18. Conclusion and bottom line
Benefits of plugs:
• Time
• Less spent on processing fish
• 30 – 45s per plug
• 3 – 10 mins per filet
• Freezer space
• Plugs: minimal
• Whole fish: large amount
• Sample homogenization
• 40 min to freeze mill 100 g of tissue
• ~1 min per plug by hand
• Humane alternative
• Practicing catch and release
18
19. Future
• Investigate correlations for lakes with varying chemical properties (e.g. eutrophic,
low ANC) and other target species (yellow perch etc.)
• More research needed to narrow the gap between predicted trend and plug line
• Create another evaluation?
• Utilize archived data sets
• Promote tagging and recapture
• Better monitoring practices
• Use the plug
19
My name is Michael
I am in the Air and Solid Waste Division
And under Waste Enforcement & Materials Management Branch
And then work with Resource Conservation & Pollution Prevention Section with Gayle Hubert doing Sustainable Food Waste Projects
This presentation covers some research that I participated in at Syracuse University
I will be presenting differences among sample preparation methods for total mercury concentration analysis in fish
As a quick note, all of my slides are numbered in the bottom right corner
Here is a general outline of the presentation
I will give you some background information about this study by defining the three methods of sample preparation
Then we’ll look over some literature reinforcing and supporting that the standard filet and plug are similar
Then, we’ll go over the objectives of this study
Next, we will compare some DEC filet and plug THg concentration regressions
Then evaluate an empirical regression to compare data sets
And finally, we’ll look over some conclusions, and future ideas of this study
Here are the objectives of this presentation
First, we’ll establish that the standard filet and plug are similar based on previous studies
Second, we’ll compare and identify DEC filet and plug regressions to determine any discrepancies
Finally, we’ll look at an empirical regression that can be utilized to predict DEC filet data and compare it to plug data
To better understand this study we have to know the similarities and differences between plugs, standard filets, and DEC filets
Plugs are a small amount of muscle tissue taken beneath the dorsal fin of a fish
Plugs do not include skin or bones
The tool that is utilized to collect the sample is called a biopsy plug
Here are two pictures that represent a biopsy tool, and where one would take plug samples
Standard filets are muscle tissues samples taken from the entire left side of the fish
Standard filets do not include skin, bones, and scales
DEC filets are similar to standard filets, but they do include skin and bones
Here is a representation of where/how a filet sample is taken
Now that we understand the three types of preparations we can reinforce how the standard filet and plug are similar based on some previous literature
Here is a study from Margret Murphy in 2009 with smallmouth bass, brown bullhead, pumpkinseed, and walleye from Onondaga Lake
These plots are represented as natural log wet weight mercury concentrations in microgram per kilogram
The x-axis represents standard filets and the y-axis represents plugs
The red dots are samples taken in 2008 and the blue dots in 2009
As you can see, the R squares among the plots is fairly strong thus representing that that there is a strong and positive correlation between the standard filets and plugs
Here are two plots from two different data sets from Syracuse University
These plots are not represented in natural log, but in regular wet weight mercury concentrations in micrograms per gram
The x- and y- axis’s again are standard filets and plugs, respectively
These plots are is represented as brook trout and yellow perch, respectively
The R square values from these plots also represent a fairly strong and positive correlation between standard filets and plugs
Now that we’ve reinforced that there is a similarity between standard filets and plugs we can look to identify and compare regressions between DEC filet and plug data
We will look at two different plots one with wet weight data that is natural logged, and then we’ll look at a plot wet weight data that is not natural logged
Here is the first plot represented as natural log wet weight mercury concentrations in micrograms per gram
The x- and y- axises are filet and plug, respectively. And here is the 1 to 1 line
As you can see, all of the species are represented here in their respective markers, and spans across multiple magnitudes
The yellow perch are on the lower end of the spectrum while the smallmouth bass are at the higher end of the spectrum.
Aside from four samples, there is a clear bias that DEC filet concentrations are low
It is hypothesized that it is because the skin and bones dilute the homogenized sample so to speak
Here are two plots that are not represented in natural log, but in regular wet weight mercury concentrations in micrograms per gram
Both plots contain all fish samples across all species and lakes
One plot represents weight in grams and the other lengths in mm plotted against total mercury concentrations of wet weight in micrograms per gram
The blue, and red lines represent DEC filet and plug regressions, respectively
As you can see for both of these plots the plug trend concentration is higher compared to the DEC filet trend
As I made these plots across all species, and lakes, plug trends were consistently higher compared to the DEC filet trends
Although the R squared values could be stronger, it is understandable that they are low because the trends span across all species with varying weights and lengths and concentrations
Now that we’ve identified some trends between DEC filet and plug data, we can evaluate an empirical relationship between DEC filet and plug data to compare it to plug data
I will first take us through how we evaluated an empirical relationship, then look at those results
So this is how we evaluated a relationship to compare DEC filet data to plugs
This method should be a fairly familiar method because our approach is similar to the length standardization method
We did this to identify the significance in the data
Starting off, as you can see, the R squared value is strong implying that for this particular case (all samples), the relationship between plugs and filets is fairly strong
Then we took the regression equation, from this plot and entered the original filet value for “x”
We labeled this value as the projected DEC filet value
This value was then plotted against mass or length to gain a regression that would be proximal to the red plug regression
As a side note we then evaluated the RPD between predicted and actual filet concentrations
These plots are the same as the two previous plots of weight and length with the x- and y- axis as weight and length, and total wet weight mercury concentrations, respectively.
Again these plots represent all samples across all species and lakes
However, notice the difference between the plots is that there is now a dotted blue line
This represents the projected DEC filet regression
As you can see on both of these plots, the DEC filet regression is fairly close in proximity to the red plug regression
Once again, although the R squares are not that strong, there is a clear visual similarity between the predicted DEC filet and plug regressions
So with this information in mind it is important to see some of the observable benefits of the plugs
The first is that it takes less time to process fish
The second is that plugs take up less storage space compared to whole fish
The third is less time spent on homogenization
And finally it’s a more humane alternative to taking the entire fish
To have stronger research we should investigate lakes’ chemical characteristics and other target species
In the future, we hope to be able to develop a more accurate and precise empirical method to apply to archived data sets to establish and compare more regressions to reduce the gap between regressions
By practicing a catch and release policy, tagging and recapture could be promoted and stronger monitoring efforts could be established
We could actually see the fluctuations in bioconcentrations a single fish
With all of this information, I personally would advise the use of the plug…
Thank you to the DEC, NYSERDA, and the lab for presenting me the opportunity to complete this research as an undergraduate
I will gladly take questions now!
