Influence of microplastic diet in laboratory on respirometry, filtration, reproduction and biomass of cladocerans (Ceriodaphnia silvestrii Daday, 1902) with the enhancing effect of increasing global temperature

• Grant number: 24/13149-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2024
• End date: September 30, 2025
• Field of knowledge: Biological Sciences - Ecology - Applied Ecology
• Principal Investigator: Gilmar Perbiche Neves
• Grantee: Ruan Tiago Jolo
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated scholarship(s): 25/01763-5 - Influence of microplastic diet and global temperature increase on filtration, reproduction, and biomass of cladocerans (Daphnia magna and Ceriodaphnia silvestrii), BE.EP.IC

Abstract

This project aims to investigate the effects of microplastics on the health and behavior of zooplankton, using the cladoceran species Ceriodaphnia silvestrii as a model organism. The research will be conducted under controlled laboratory conditions to evaluate the impact of microplastic ingestion on critical aspects such as feeding behavior, reproduction, growth, and respiratory activity under different thermal conditions.Microplastics, plastic particles smaller than 5 mm, are classified as primary (intentionally incorporated into cosmetic and cleaning products) and secondary (formed by the degradation of larger plastics). Their persistent and widespread presence in the aquatic environment has raised concerns due to their potential to impact marine organisms and, consequently, ecosystems. Zooplankton, essential for the marine food chain and nutrient cycle, may suffer adverse effects from ingesting microplastics, such as reduced feeding rate, growth, and fecundity. Laboratory studies indicate that prolonged exposure to microplastics can negatively affect the organisms' energy metabolism and cause reproductive health and development issues.This study will be conducted with C. silvestrii, fed with the microalga Raphidocelis subcapitata, and exposed to 6.0 ¼m polystyrene spheres at average concentrations of 1x10^5 spheres/L. Experiments will be performed at two temperatures, 25°C and 29°C, to simulate global warming conditions. The following parameters will be analyzed: respiration rate (metabolic rate), filtration rate (feeding behavior), reproduction (number of neonates), and growth (biomass).The methodology includes the collection and cultivation of organisms, acclimatization in temperature-controlled beakers, and the addition of microplastics to the individuals' diets. The organisms will be screened and cultured up to the third generation to ensure result consistency. Respiration rate will be measured by respirometry, while filtration rate will be obtained by flow cytometry. Biomass analyses will be conducted using Bottrell et al.'s (1976) equation to estimate the dry weight of individuals. To ensure result accuracy, experiment replicates will be conducted, and rigorous statistical analysis will be performed.Data will be analyzed using R software, with ANOVA tests and t-tests to compare respiration and reproduction rates between exposed and control groups. A correlation analysis will also be performed to relate the amount of ingested microplastics with physiological and reproductive parameters. This study will contribute to understanding the impacts of microplastics on aquatic ecosystems and provide insights for conservation and environmental management.Furthermore, the study aims to evaluate how climate change may exacerbate the effects of microplastics on zooplankton. Projections indicate that ocean temperatures will continue to rise in the coming decades, potentially amplifying the negative effects of microplastics. Analyzing effects at 25°C and 29°C will allow for a more detailed understanding of how global warming might influence microplastic toxicity.It is expected that the results of this project will reveal important patterns regarding the interaction between microplastics and zooplankton, particularly in the context of a changing climate. The findings will be presented at national and international scientific events and submitted for publication in specialized journals, contributing to the advancement of scientific knowledge on plastic pollution and climate change.