Rationale:

As a result of the rise of single use plastic products, microplastics, or plastic shards with volumes between 1 cm³ to 1 nm³ have continued to build up in global ecosystems. As microplastics are becoming extremely common in our waters and on our beaches, a group of researchers from Rutgers University designed and executed a study ¹ that sought to determine the effects of microplastics on the growth and development of zebrafish. The group found that exposure to high density polyethylene (HDPE) microplastics at a concentration of 10 μg/mL caused inflammation to the pericardial sacs of larval zebrafish. Also, the total body length of the larval zebrafish was increased. These differences prevent the larval zebrafish from swimming quickly and escaping predators in their natural habitat. 

As these effects negatively impact the zebrafish species and their food webs, I intend to build upon the community’s understanding by extending the study to span over multiple generations and include two fish species. Additionally, I will study acrylates copolymer microbeads, a common microbead found in countless facial scrubs and soaps instead of HDPE. As over eight trillion microbeads are released into the environment each day ², it is important that the scientific community understands the effects of microbeads on marine organisms. 

This project will increase the scientific community’s understanding of microplastics’ impact on ecosystems. Since microplastics are a relatively new topic of study, their biological and ecological effects are not widely understood by the scientific community. Also, microplastics could potentially affect other organisms the same way that they affect zebrafish. Humans likely consume microplastics via seafood, leading to a case of biomagnification. As humans are thus consuming more plastic than fish, the health issues that come with plastic consumption could potentially be significant. By determining the effects of microplastics on guppies over multiple generations, the scientific community will have a larger understanding of how microplastics impact the marine ecosystem as a whole.

Currently, I have collected initial data and am beginning to collect experimental data. Although I have not completed my experiment yet and I am unable to draw conclusions at this point in time, I believe that it is important that I share my design and ideas with the scientific community. 

Research Question and Hypothesis:

This study seeks to determine if exposure to acrylates copolymer microbeads causes changes in growth in guppies (Poecilia reticulata) and/or Kuhli loaches (Pangio kuhlii), specifically in their total body lengths, tail lengths, masses, and/or pericardial sac lengths. As a result, it is hypothesized that exposure to acrylates copolymer microbeads will cause guppies (Poecilia reticulata) and Kuhli loaches (Pangio kuhlii) to develop inflamed pericardial sacs, total body lengths, and tail lengths. 

Procedure:

Experimental Design:

Firstly, I will prepare two fifteen gallon aquariums for the trials. The aquariums will be set up so that one will contain acrylates copolymer microbeads at a concentration of 10 μg/mL, and the other will be a control tank containing no microplastics sample. The acrylates copolymer sample will be obtained by washing Clean and Clear Morning Burst Facial Scrub through filter paper and collecting the remaining microbeads. To prepare the aquariums, I will measure out the acrylates copolymer sample needed to satisfy the necessary concentration for the experimental aquarium. Next, I will add four breeding nets to each tank, allowing the guppy offspring to be able to grow and develop in an environment safe from possible predators. Before experimental trials begin, I will take initial measurements of all fish using the Measurement Procedure. Once the tanks have been prepared, I will transfer five pregnant female guppies raised in a controlled environment into each tank, and place one to two guppies in each breeding net. Then, I will add five Kuhli loaches to each tank. Next, I will measure each fish every week using the Measurement Procedure. All fish will be fed tropical fish food once per day. I will collect data for three breeding generations. 

The data will be analyzed using statistical analysis. The weekly measurements will be averaged for each generation and plotted on a line graph, with time being the independent variable and the measurement being the dependent variable. Also, statistical inference tests will be used to compare the two groups, and to determine if the exposure to microbeads caused a significant change in growth. Specifically, a matched pairs T test will be used to determine if the control group and the experimental group have different growth patterns. 

Measurement Procedure:

Firstly, I will obtain a fish, and place it in a petri dish with 5mL of water. Next, I will proceed to measure the fish’s total body length and top tail length with a millimeter ruler. Additionally, the fish’s mass will be measured using an electronic balance. Also, each guppy’s pericardial sac will be measured under a microscope with a nanometer ruler. I will then record the fish’s identifying number and all of the corresponding data in a data table. 

Risk and Safety:

No safety issues will be encountered in this study. This is because I am not working with hazardous chemicals or engaging in dangerous activities. The acrylates copolymer microbeads were obtained from Clean and Clear Morning Burst facial scrub. The product is available commercially and was subject to extensive testing on humans before arriving on the market as a hygiene product. 

Bibliography:

¹ Moreno, Gina, et al. Microplastics in Urban New Jersey Freshwaters: Distribution, Chemical Identification, and Biological Affects. Rutgers University, 2017.

² Cheung, Pui Kwan, and Lincoln Fok. “Characterisation of Plastic Microbeads in Facial Scrubs and Their Estimated Emissions in Mainland China.” Water Research, vol. 122, 2017, pp. 53–61., doi:10.1016/j.watres.2017.05.053.

Mylett, T. Y. “Notes on the Care of Common and Fancy Guppy (Poecilia Reticulata).” INDEPENDENT WILDFOWL AND GENERAL ORNITHOLOGICAL STUDIES, Feb. 2019, www.researchgate.net/publication/331135904_Notes_on_the_care_of_Common_and_Fancy_Guppy_Poecilia_reticulata.