Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Project Information
• Funding

Copepods were collected in June of 2016 from Esker Point Beach in Groton, Connecticut, USA (41.320725°N, 72.001643°W) and raised for at least three generations as stock cultures prior to the start of transgenerational experiments to limit maternal effects (Falconer, 1989. Introduction to Quantitative Genetics). Stock cultures were split evenly into eight groups of 160 females and 80 males. Four of these eight groups were acclimatized to high temperature at 1 degree Celsius per day and used to seed the two high temperature treatments (OW and OWA). The other four groups remained at ambient temperature and were used to seed the ambient and acidification treatments. After temperature acclimatization, groups of stock cultures seeded the parental (F0) individuals for two days. Stock culture groups yielded an average of 7,173 eggs per group to produce approximately 57,000 parental (F0) eggs. Resulting parental eggs and N1 nauplii were acclimated to one of four experimental treatments over the entire F0 generation. The four lines of the copepods were established with four replicates of each condition. The target (actual ± standard deviation) conditions were: ambient temperature = 18 degrees Celsius (°C) (18 ± 0.34, N = 330), ambient pCO2 = 400 μatm (379 ± 36, N = 18; pH = 8.26 ± 0.1, N = 330); high temperature = 22°C (22 ± 0.81, N = 336), and high pCO2 = 2000 µatm (2301 ± 215, N = 18; pH = 7.55 ± 0.08, N = 330). Copepods were fed every 48-72 hours at food-replete concentrations (≥800 micrograms (μg) Carbon per liter (L)) consisting of equal proportions of the phytoplankters Tetraselmis sp., Rhodomonas sp., and Thalassiosira weissflogii, deliberately raised under ambient conditions for the entire length of the experiment to avoid confounding effects of possible changes in food quality due to the different temperature and CO2 among treatments.

The population net reproductive rate, λ, was calculated as the dominant eigenvalue of an assembled projected age-structured Leslie matrix constructed from survival and fecundity data (Caswell, H. 2001. Matrix Population Models: Construction, Analysis, and Interpretation). Briefly, day-specific probabilities of survival are calculated from day-specific survival as Px = l_x /(l_x−1) where l_x represents the proportion of individuals on day x and l_x - 1 represents the proportion of individuals on day x − 1. Probabilities of survival on day 1 are assumed to be 100%, or a value of 1.0. EPR was calculated as (E_u+E_h)/t where E_u represents unhatched eggs, E_h represents hatched eggs (nauplii) and t represents egg-laying time. HS was calculated as E_h/(E_u+E_h). Fecundity rates equal the product of EPR and HS. Because only females produce offspring, total fecundity rates must be scaled to the sex ratio (proportion of females to males). To account for differences in individual development time for each treatment, fecundity rates are assigned to all days after the first matured adult is observed. We assume that surviving individuals represented by the survival experiments are equally as likely to experience any of the fecundity values observed in EPR experiments. Therefore, each mate-pair fecundity rate was paired with each survival beaker to construct a matrix. This yields a maximum of 120 matrices per treatment per generation (3 survival beakers × 4 replicate cultures × 10 mate pairs). Relative measures of each value are calculated as the trait value divided by the mean value of that trait. Standardized measures of each value are calculated as the trait value minus the mean trait value and divided by the standard deviation. The target (actual ± standard deviation) conditions were as follows: ambient (AM) temperature = 18 °C (18 ± 0.34, N = 330), AM pCO2= 400 μatm (379 ± 36, N = 18; pH = 8.26 ± 0.1, N = 330); high temperature = 22 °C (22 ± 0.81, N = 336); and high pCO2= 2,000 µatm (2,301 ± 215, N = 18; pH = 7.55 ± 0.08, N = 330). AM target levels represented extant conditions for this species in northeast Atlantic estuaries. Full methods can be found in Dam, et al. 2021 Nature Climate Change. doi: 10.1038/s41558-021-01131-5.

Data were processed and analyzed with R (v 4.0.2). Code for data analysis and visualization is located in Zenodo at: https://doi.org/10.5281/zenodo.5115103.

- Imported original file "lambda_results_devtime_surv_epr_hf_sex_standardized_relative.txt" into the BCO-DMO system.
- Renamed fields to comply with BCO-DMO naming conventions.
- Saved final file as "923908_v1_a_tonsa_population_fitness.csv".

NSF Award Abstract:
Over time, our oceans are becoming both warmer and higher dissolved carbon dioxide. The latter condition is called ocean acidification. The consequences of these simultaneous changes for populations of marine organisms are not well understood. For this project, the investigators will conduct a series of laboratory experiments to determine how two closely-related, common species of Acartia copepods will respond to the interactive effects of warming and acidification and also how well these species can adapt over multiple generations to changing ocean conditions. Since these copepods are key species in coastal food webs, results will have important implications for understanding and predicting how marine ecosystems may respond to future climate change. The investigators will share results from the research through traditional print media, case studies, and video mini lectures. The goal will be for educators of all levels to easily access material on climate change and ocean acidification to include in teaching curricula, in alignment with recommendations for universal design for learning. The project is a collaborative effort between an established professor at the University of Connecticut and an early-career female scientist at the University of Vermont. It will provide training and opportunities for collaborative, interdisciplinary research for two postdoctoral investigators, two graduate students and an undergraduate student.

The project's main goals are: 1) to test the simultaneous effects of temperature and carbon dioxide under current and future conditions on life history traits throughout the life cycle for two key copepod species, warm-adapted Acartia tonsa and cold-adapted Acartia hudsonica; 2) to test for adaptive capacity of both copepod species to a warmer and carbon-dioxide-enriched ocean; 3) to measure the genetic and maternally-induced changes across multiple generations of experimental selection in future conditions in both copepod species, and to identify the genes and pathways responding to selection. The investigators will use experiments encompassing current and projected temperature and carbon-dioxide conditions, will determine the roles of each variable and their interaction on traits that affect the fitness of both copepod species. They will also determine which life stages are most sensitive to individual or simultaneous stress conditions. Through multigenerational selection experiments, the investigators will identify and characterize the mechanisms of copepod evolutionary adaptation. Finally, they will measure genomic changes across the generations under all four experimental conditions to quantify the relative contributions of genetic and maternally-induced change in the physiological and life history traits of copepods in response to near-future climate conditions.