The presence of microfibers and microplastics in the environment is an ever-growing ecological concern. Accumulation of microplastics (plastic particles smaller than 5 mm) in aquatic environments and the subsequent exposure of these particles to organisms have been shown to have negative effects on aquatic biota. As an invasive, filter-feeding bivalve found across Indiana freshwater ecosystems, the zebra mussel (Dreissena polymorpha) serves as a good model organism for studying microplastics’ effects on physiological and behavioral functions of affected organisms. We have studied the impacts of microplastic exposure on a freshwater mollusk, the zebra mussel. We collected zebra mussels from Stone Lake, Indiana, in late fall of 2019. Individual zebra mussels were exposed to polypropylene rope fibers (concentration of rope fibers in the environment of one zebra mussel was ~400 microfibers per L) for 24-hour trials and assessed the effects by production of byssal threads, which are produced by the zebra mussel for anchorage and in response to predation threats. Results from a comparison between unexposed control mussels (n=70) and mussels exposed to rope fibers (n=70) revealed no significant difference in motility nor the number of byssal threads produced. Despite using microplastic concentrations that were higher than that found in the Great Lakes, a 24 hour exposure time may still not have been enough to significantly impact the animals. Continued research on the attachment strength of Dreissena polymorpha exposed to rope fibers will provide clearer evidence of any direct effect of these microplastics on the ecologically important mussel species

Crisman, Anna-Christina Z.

Eberhardt, Laurie

Iceman, Christopher

Kostelnik, Eddie

Peller, Julie

English

Valparaiso University

Valparaiso University ValpoScholar Symposium on Undergraduate Research and Creative Expression (SOURCE) Office of Sponsored and Undergraduate Research Spring 5-1-2020 The effect of polypropylene on the formation of byssal threads produced by Dreissena polymorpha (zebra mussels) Anna-Christina Z. Crisman Valparaiso University, anna.crisman@valpo.edu Anna-Christina Z. Crisman Valparaiso University, thomas.paul@valpo.edu Laurie Eberhardt Valparaiso University Eddie Kostelnik Valparaiso University, eddie.kostelnik@valpo.edu Julie Peller Valparaiso University See next page for additional authors Follow this and additional works at: https://scholar.valpo.edu/cus Recommended Citation Crisman, Anna-Christina Z.; Crisman, Anna-Christina Z.; Eberhardt, Laurie; Kostelnik, Eddie; Peller, Julie; and Iceman, Christopher, "The effect of polypropylene on the formation of byssal threads produced by Dreissena polymorpha (zebra mussels)" (2020). Symposium on Undergraduate Research and Creative Expression (SOURCE). 869. https://scholar.valpo.edu/cus/869 This Poster Presentation is brought to you for free and open access by the Office of Sponsored and Undergraduate Research at ValpoScholar. It has been accepted for inclusion in Symposium on Undergraduate Research and Creative Expression (SOURCE) by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. Authors Anna-Christina Z. Crisman, Anna-Christina Z. Crisman, Laurie Eberhardt, Eddie Kostelnik, Julie Peller, and Christopher Iceman This poster presentation is available at ValpoScholar: https://scholar.valpo.edu/cus/869 The effect of polypropylene on the formation of byssal threads produced by zebra mussels (Dreissena polymorpha)Anna-Christina Z. Crisman1, Thomas G. Paul1, Laurie S. Eberhardt1, Eddie Kostelnik2, Christopher Iceman2, Julie Peller21Department of Biology, 2Department of Chemistry, Valparaiso University IntroductionAs a result of human activity and reliance on plastic products, microplastics and fibers are becoming a major ecological problem in both terrestrial and aquatic environments. These particles - which are less than 5 millimeters large - become ingested by organisms and pose a risk to them as well as others along the food chain (Galloway and Lewis 2016). Previous studies of microplastic effects have been conducted on bivalves; oysters experience decreased reproduction and larval development (Susarellu et al. 2016). However, the behavioral effects of plastic and fiber uptake are relatively unknown. The zebra mussel (Dreissenapolymorphia) is a possible indicator of microplastics’ effect in water systems; it is an invasive bivalve found in many water systems including the Great Lakes and can filter large quantities of water in a short period of time (Figure 1). In order to anchor themselves to substrates, zebra mussels produce byssal threads which have adhesive flared ends called “plaques” (Figure 2 ). The plaques and threads together anchor the mussel in place (Farsad N. and Sone ED, 2012) and may be important in predator avoidance (Krobak and Karkareko 2009). The objective of this study was to examine how the amount of byssal threads produced by zebra mussels would change in response to microplastics in the mussels’ environment. This experiment can show if microplastics significantly change zebra mussel behavior, which could open up possibilities for further research and understandings of the larger ecological effects and implications of such pollutants.Figure 1: Dreissena polymorphaextending muscular foot for movement. Filter-feeding “siphon” is also visible.Figure 2: Byssal threads produced by zebra mussel. The flared ends are the “plaques” which are quantified in the study.Methods• The mussels were retrieved from Stone Lake, Indiana, in September and October, 2019 (Figure 3).• Seven trials were conducted between October 25, 2019 and January 30, 2020. • For each trial, we set up 10 fingers bowls of 200 mL of experimental water (~ 400 microfibers per liter of aged polypropylene rope fiber) and 10 fingers bowls of 200 mL of control water. Each finger bowl contained one zebra mussel (Figure 4).• Water came directly from the stock mussel tanks and was originally from their source lake.• We allowed the mussels 24 hours to attach to the fingerbowls before detaching the mussels with a sharp blade and examining the bowls under a microscope to record the number of plaques left behind.Figure 3: Collecting zebra mussels at Stone Lake, IndianaFigure 4: Setting up a trial. Each fingerbowl contained a zebra musselResults• 140 mussels were used, and each was exposed to its respective condition for 24 hours on average.• Although some mussels did not produce byssal threads during the experiment, we found no differences in the number of mussels that attached between experimental and control treatments (X2=0.679, p>0.05)• As seen in figures 5, 6, and 7, of those mussels that did attach, we found no significant different in the average number of plaques between the control condition and the experimental condition for either total number of plaques (t=1.06 df=138, p=0.14) or plaque number divided by mussel size (t=1.98,  df=102, p= 0.6). • No significant difference between ingested fibers in control and experimental mussels using UV oxidation to separate fibers from mussels (control: m=1.75 +/-1.71; exp: m= 2.6 +/- 1.14).Figure 5: Average number of plaques for control and experimental conditions, excluding mussels which did not attach. Error bars represent + - SD.Discussion• Presence of microplastics did not significantly affect the number of byssal threads with plaques produced in this study.• The concentration of microplastics that the mussels were exposed to in this study was much higher than the reported concentration of plastic in Lake Michigan, which is 1.9 - 32 particles per cubic meter (Baldwin et al. 2016).• However, the exposure time to plastics could have been too short and not allowed the mussels to ingest plastic for significant differences to be seen (control: m=1.75, exp: m= 2.6). Therefore, future experiments could involve increasing exposure time.• Additional considerations include different ages of mussels across trials, possible over or underfeeding of mussels, and the possibility of mussels already habituated to plastics due to plastic presence in Stone Lake.• The mussels were also less mobile in later trials; more of them were found unattached and not having changed position in their finger bowls compared to earlier trials where they were more likely found clinging to the vertical sides of the finger bowls.  However, no significant differences between treatments were revealed when these trials were excluded.• Future version of this experiment should examine the long term effects of microplastics on mussel behavior as opposed to short trials.AcknowledgementsWe would like to thank Cody Banks, Kalleb Miller, and Cole Phillips, for assistance with various aspects of this research.References• Baldwin AK, Corsi SR, and Mason SA. Plastric debris in 29 great lakes tributaries: relations to watershed attributes and hydrology. Environmental Science Technology. 50(19): 10377-10385.• Farsad N. and Sone ED. 2012. Zebra mussel adhesion: structure of the byssal adhesive apparatus in the freshwater mussel, Dreissena polymorpha. Journal of Structural BIology. 177(3):613-620.• Galloway TS, Lewis CN. 2016. Marine microplastics spell big problems for future generations. Proceedings of the National Academy of Sciences. 113(9): 2331-2333.• Sussarellu R, Suquet M, Thomas Y, Lambert C, Fabioux C, Pernet MEJ, Goic NL, Quillien V, Mingant C, Epelboin Y, et al. 2016. Oyster reproduction is affected by exposure to polystyrene microplastics. Proceedings of the National Academy of Sciences. 113(9): 2430-2435051015202530Average Number of PlaquesExperimentalAverage Number of Plaques Between Conditions**Attached MusselsControlFigure 6: For mussels across all trials which did attach, size vs. number of plaques is plotted. Across both test groups, larger mussels generally produced more threads.00.10.20.30.40.51Average Number of Plaques Controlled for Size of MusselsExperimental ControlFigure 7: Comparison of the number of plaques divided by the size (l x w) of each mussel, excluding mussels which did not attach.R² = 0.2025R² = 0.252901020304050600 5 10 15 20Average Number of PlaquesLength (mm)Mussel Size vs. Plaques Produced**Attached MusselsExperimentalControlLinear (Experimental)

The effect of polypropylene on the formation of byssal threads produced by Dreissena polymorpha (zebra mussels)

ValpoScholar

Valparaiso University 
ValpoScholar 
Symposium on Undergraduate Research and 
Creative Expression (SOURCE) 
Office of Sponsored and Undergraduate 
Research 
Spring 5-1-2020 
The effect of polypropylene on the formation of byssal threads 
produced by Dreissena polymorpha (zebra mussels) 
Anna-Christina Z. Crisman 
Valparaiso University, anna.crisman@valpo.edu 
Anna-Christina Z. Crisman 
Valparaiso University, thomas.paul@valpo.edu 
Laurie Eberhardt 
Valparaiso University 
Eddie Kostelnik 
Valparaiso University, eddie.kostelnik@valpo.edu 
Julie Peller 
Valparaiso University 
See next page for additional authors 
Follow this and additional works at: https://scholar.valpo.edu/cus 
Recommended Citation 
Crisman, Anna-Christina Z.; Crisman, Anna-Christina Z.; Eberhardt, Laurie; Kostelnik, Eddie; Peller, Julie; 
and Iceman, Christopher, "The effect of polypropylene on the formation of byssal threads produced by 
Dreissena polymorpha (zebra mussels)" (2020). Symposium on Undergraduate Research and Creative 
Expression (SOURCE). 869. 
https://scholar.valpo.edu/cus/869 
This Poster Presentation is brought to you for free and open access by the Office of Sponsored and Undergraduate 
Research at ValpoScholar. It has been accepted for inclusion in Symposium on Undergraduate Research and 
Creative Expression (SOURCE) by an authorized administrator of ValpoScholar. For more information, please 
contact a ValpoScholar staff member at scholar@valpo.edu. 
Authors 
Anna-Christina Z. Crisman, Anna-Christina Z. Crisman, Laurie Eberhardt, Eddie Kostelnik, Julie Peller, and 
Christopher Iceman 
This poster presentation is available at ValpoScholar: https://scholar.valpo.edu/cus/869 
The effect of polypropylene on the formation of byssal threads produced by 
zebra mussels (Dreissena polymorpha)
Anna-Christina Z. Crisman1, Thomas G. Paul1, Laurie S. Eberhardt1, Eddie Kostelnik2, Christopher Iceman2, Julie Peller2
1Department of Biology, 2Department of Chemistry, Valparaiso University 
Introduction
As a result of human activity and reliance on plastic products, microplastics and 
fibers are becoming a major ecological problem in both terrestrial and aquatic 
environments. These particles - which are less than 5 millimeters large - become 
ingested by organisms and pose a risk to them as well as others along the food 
chain (Galloway and Lewis 2016). Previous studies of microplastic effects have 
been conducted on bivalves; oysters experience decreased reproduction and 
larval development (Susarellu et al. 2016). However, the behavioral effects of 
plastic and fiber uptake are relatively unknown. The zebra mussel (Dreissena
polymorphia) is a possible indicator of microplastics’ effect in water systems; it is 
an invasive bivalve found in many water systems including the Great Lakes and 
can filter large quantities of water in a short period of time (Figure 1). In order to 
anchor themselves to substrates, zebra mussels produce byssal threads which 
have adhesive flared ends called “plaques” (Figure 2 ). The plaques and threads 
together anchor the mussel in place (Farsad N. and Sone ED, 2012) and may be 
important in predator avoidance (Krobak and Karkareko 2009). The objective of 
this study was to examine how the amount of byssal threads produced by zebra 
mussels would change in response to microplastics in the mussels’ environment. 
This experiment can show if microplastics significantly change zebra mussel 
behavior, which could open up possibilities for further research and 
understandings of the larger ecological effects and implications of such pollutants.
Figure 1: Dreissena polymorpha
extending muscular foot for 
movement. Filter-feeding “siphon” is 
also visible.
Figure 2: Byssal threads produced by zebra 
mussel. The flared ends are the “plaques” 
which are quantified in the study.
Methods
• The mussels were retrieved from Stone Lake, Indiana, in September and October, 
2019 (Figure 3).
• Seven trials were conducted between October 25, 2019 and January 30, 2020. 
• For each trial, we set up 10 fingers bowls of 200 mL of experimental water (~ 400 
microfibers per liter of aged polypropylene rope fiber) and 10 fingers bowls of 200 
mL of control water. Each finger bowl contained one zebra mussel (Figure 4).
• Water came directly from the stock mussel tanks and was originally from their 
source lake.
• We allowed the mussels 24 hours to attach to the fingerbowls before detaching 
the mussels with a sharp blade and examining the bowls under a microscope to 
record the number of plaques left behind.
Figure 3: Collecting zebra mussels 
at Stone Lake, Indiana
Figure 4: Setting up a trial. 
Each fingerbowl contained 
a zebra mussel
Results
• 140 mussels were used, and each was exposed to its respective condition for 24 
hours on average.
• Although some mussels did not produce byssal threads during the experiment, we 
found no differences in the number of mussels that attached between experimental 
and control treatments (X
2
=0.679, p>0.05)
• As seen in figures 5, 6, and 7, of those mussels that did attach, we found no 
significant different in the average number of plaques between the control condition 
and the experimental condition for either total number of plaques (t=1.06 df=138, 
p=0.14) or plaque number divided by mussel size (t=1.98,  df=102, p= 0.6). 
• No significant difference between ingested fibers in control and experimental 
mussels using UV oxidation to separate fibers from mussels (control: m=1.75 +/-
1.71; exp: m= 2.6 +/- 1.14).
Figure 5: Average number 
of plaques for control and 
experimental conditions, 
excluding mussels which 
did not attach. Error bars 
represent + - SD.
Discussion
• Presence of microplastics did not significantly affect the number of byssal threads 
with plaques produced in this study.
• The concentration of microplastics that the mussels were exposed to in this study 
was much higher than the reported concentration of plastic in Lake Michigan, which 
is 1.9 - 32 particles per cubic meter (Baldwin et al. 2016).
• However, the exposure time to plastics could have been too short and not allowed 
the mussels to ingest plastic for significant differences to be seen (control: m=1.75, 
exp: m= 2.6). Therefore, future experiments could involve increasing exposure time.
• Additional considerations include different ages of mussels across trials, possible 
over or underfeeding of mussels, and the possibility of mussels already habituated to 
plastics due to plastic presence in Stone Lake.
• The mussels were also less mobile in later trials; more of them were found 
unattached and not having changed position in their finger bowls compared to 
earlier trials where they were more likely found clinging to the vertical sides of the 
finger bowls.  However, no significant differences between treatments were revealed 
when these trials were excluded.
• Future version of this experiment should examine the long term effects of 
microplastics on mussel behavior as opposed to short trials.
Acknowledgements
We would like to thank Cody Banks, Kalleb Miller, and Cole Phillips, for assistance with various 
aspects of this research.
References
• Baldwin AK, Corsi SR, and Mason SA. Plastric debris in 29 great lakes tributaries: relations to 
watershed attributes and hydrology. Environmental Science Technology. 50(19): 10377-10385.
• Farsad N. and Sone ED. 2012. Zebra mussel adhesion: structure of the byssal adhesive apparatus 
in the freshwater mussel, Dreissena polymorpha. Journal of Structural BIology. 177(3):613-620.
• Galloway TS, Lewis CN. 2016. Marine microplastics spell big problems for future generations. 
Proceedings of the National Academy of Sciences. 113(9): 2331-2333.
• Sussarellu R, Suquet M, Thomas Y, Lambert C, Fabioux C, Pernet MEJ, Goic NL, Quillien V, 
Mingant C, Epelboin Y, et al. 2016. Oyster reproduction is affected by exposure to polystyrene 
microplastics. Proceedings of the National Academy of Sciences. 113(9): 2430-2435
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Figure 7: Comparison of the 
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R² = 0.2529
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*Attached Mussels
Experimental
Control
Linear 
(Experimental)


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The effect of polypropylene on the formation of byssal threads produced by Dreissena polymorpha (zebra mussels)

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