Table of Contents

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

Acartia tonsa individuals were collected in July from Esker Point, Connecticut in Eastern Long Island Sound in July of 2021. Laboratory cultures were established and maintained at 18°C, with a 12:12 light:dark cycle. To initiate the experiment, nauplii were collected from the laboratory culture and split into two groups, which were either maintained under rearing conditions or exposed 28°C for 24 hours. For the remaining duration of the experiment, all individuals were held at 18°C in individual petri dishes and fed ad libitum a mixture of Tetraselmis sp. and Rhodomonas salina. 

Individual copepods were then tracked through development by examining the petri dish daily for the presence of a molted exoskeleton.  Respiration rates were measured for each individual starting in the first copepodite stage, with proceeding measurements during each successive stage. During these measurements, individuals were isolated in 2 ml glass vials with an oxygen sensor spot attached to the base. Oxygen levels were measured every three minutes using a Presens sensor dish reader. Assays typically ran for approximately eight hours. Individual lengths were measured using an inverted compound microscope and attached digital camera, and then individuals were returned to their petri dish with fresh medium. Upon reaching maturity (the sixth copepodite stage), respiration and body size was measured as above and then individual sex was recorded. 

In addition to the individuals measured at every stage, a group of individuals had measurements made only in the sixth and final stage, serving as a handling control group to test for effects of repeated handling on respiration or body size. The entire experiment (comprising naupliar heat stress, individual measurements through development, and handling control measurements) was repeated three separate times. 

Organism identifiers (Life Science Identifier (LSID))
copepod, Acartia tonsa, urn:lsid:marinespecies.org:taxname:345943
feeding medium, Rhodomonas salina, urn:lsid:marinespecies.org:taxname:106316
feeding medium, Tetraselmis sp., urn:lsid:marinespecies.org:taxname:134526

Respiration rates were calculated as the linear change in oxygen concentration over time (milliliter oxygen per hour). The code utilized for these calculations is included in the referenced Zenodo holding (doi: 10.5281/ZENODO.7434983). 

* Data from submitted file "holmes-hackerd et al 2022 data.csv" was imported into the BCO-DMO data system for this dataset. Values "NA" imported as missing data values.   Table will appear as Data File: 955729_v1_a-tonsa-ontogenetic-resipration.csv (along with other download format options).

Missing Data Identifiers:
* In the BCO-DMO data system missing data identifiers are displayed according to the format of data you access. For example, in csv files it will be blank (null) values. In Matlab .mat files it will be NaN values. When viewing data online at BCO-DMO, the missing value will be shown as blank (null) values.

* Date converted to ISO 8601 format

* Organism LSIDs added from matches at the World Register of Marine Species (WoRMS) on 2025-03-11

NSF Award Abstract:

Many parts of the ocean are warming rapidly, but it is still unknown how this warming will affect marine food webs. Copepods, small crustaceans, are the most abundant animals in the ocean; consequently, they play crucial roles in plankton marine food webs and in the transfer of energy to fishes. Many species of copepods are able to choose between prey such as microscopic plants and single-celled animals. The choice affects how energy moves through marine food webs. Past work suggests that increasing temperature should favor herbivory over carnivory. This project is investigating whether this prediction holds in the face of genetic adaptation to warming in highly seasonal systems such as coastal temperate zones. Results from this study are contributing to understanding and predicting the response of marine ecosystems to future climate conditions, as well as for planning and implementing sustainable fisheries management plans. Other broader impacts include the development of learning modules for high school and college students. Hands-on science exhibits for K-6 students and public presentations at established lecture series focus on the role of copepods in marine food webs in coastal habitats.

Predicting responses of the oceanic biota to climate change is limited not only by an incomplete understanding of how warming affects ecological interactions and evolutionary dynamics individually, but also by how these two factors interact. Copepods are both grazers of phytoplankton and predators of microzooplankton in marine systems. Increasing temperatures may drive a large-scale shift in the diet of omnivorous copepods towards stronger herbivory, with significant consequences for the structure of marine food webs and the control of primary productivity. However, thermal adaptation may moderate or even nullify these shifts. This project examines the interactive role ecological and evolutionary dynamics plays in shaping grazing and individual fitness in a warming ocean. The main goals of the project are to: 1) quantify seasonal variation in thermal performance curves in dominant coastal copepod species; 2) determine whether observed seasonal variation in thermal performance is caused by genetic differentiation or phenotypic plasticity; 3) assess how temperature affects respiration and protein synthesis rates, selective feeding, and individual fitness; and 4) determine how changes in the thermal performance curve, via both genetic differentiation and phenotypic plasticity, affect the relationship between temperature and food preference. Selective feeding experiments are being paired with measurements of egg production and hatching success across a wide range of temperatures to measure thermal effects on feeding selectivity and individual fitness. Finally, genetic differentiation and phenotypic plasticity on temperature sensitivity is being investigated across populations from environments that differ in their thermal regime. The outcomes of this project contribute to the parameterization of models that forecast fisheries dynamics in response to climate change.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.