Skip to main content
Dryad

Developmental temperature, more than long-term evolution, defines thermal tolerance in an Estuarine Copepod

Ashlock, Lauren1

Published Feb 23, 2024 on Dryad. https://doi.org/10.5061/dryad.wm37pvmvb

Cite this dataset

Ashlock, Lauren (2024). Developmental temperature, more than long-term evolution, defines thermal tolerance in an Estuarine Copepod [Dataset]. Dryad. https://doi.org/10.5061/dryad.wm37pvmvb

Abstract

Climate change is resulting in increasing ocean temperatures and salinity variability, particularly in estuarine environments. Tolerance of temperature and salinity change interact and thus may impact organismal resilience. Populations can respond to multiple stressors in the short-term (i.e., plasticity) or over longer timescales (i.e., adaptation). However, little is known about the short- or long-term effects of elevated temperature on the tolerance of acute temperature and salinity changes. Here we characterized the response of the near-shore and estuarine copepod, Acartia tonsa, to temperature and salinity stress. Copepods originated from one of two sets of replicated >40 generation-old temperature adapted lines: Ambient (AM, 18°C) and ocean warming (OW, 22°C). Copepods from these lines were subjected to one and three generations at the reciprocal temperature. Copepods from all treatments were then assessed for differences in acute temperature and salinity tolerance. Development (one generation), three generations, and >40 generations of warming increased thermal tolerance compared to Ambient conditions, with development in OW resulting in equal thermal tolerance to three and >40 generations of OW. Strikingly, developmental OW and >40 generations of OW had no effect on low salinity tolerance relative to Ambient. By contrast, when environmental salinity was reduced first, copepods had lower thermal tolerances. These results highlight a critical role for plasticity in the copepod climate response and suggest that salinity variability may reduce copepod tolerance to subsequent warming.

README: Developmental temperature, more than long-term evolution, defines thermal tolerance in an estuarine copepod

DOI: 10.5061/dryad.wm37pvmvb

This dataset contains five data files. The first data file contains results from an experimental evolution study in the copepod, Acartia tonsa. In this study we examined the effect of ocean warming on the upper lethal temperature  of A. tonsa. The second file contains results from the same study, where we instead looked at the impact of ocean warming on lower lethal salinity. In the third file, we examined the impact of rapid salinity change on upper lethal temperature in the copepod A. tonsa. The last two files contain supplementary data that were used for supplemental figures. These files contain data from preliminary experiments where upper lethal temperature and lower lethal salinity were tested.

1)  UCONN_ULT_Final
2)  UCONN_LLS_Reps_NoTreat
3)  SalinityTemp
4)  LHS_ctmax_Complete
5)  UCONN_GradualSalinity_Trial

Description of the data and file structure

In UCONN_ULT_Final there are six variables: Line, Replicate, Treatment, Group, Condition, and ULT. These variables are defined below.

  • Line: Categorical variable with two levels, Control and HighTemp. Control line animals were from UConn lines held at 18C and HighTemp line animals were from UConn lines held at 22C.
  • Replicate: This categorical variable has four levels referring to which replicate line animals originated from.
  • Treatment: Categorical variable with two levels Ambient and OceanWarming. Animals at Ambient were held at 18C at the time of the upper lethal temperature assay. Animals at OceanWarming were held at 22C at the time of the upper lethal temperature assay.
  • Group: Six level categorical variable defining each unique combination of line and treatment.
  • Condition: This variable is redundant to Group, with a different naming scheme for analysis in R.
  • ULT: Continuous variable, upper lethal temperature values for individual copepods.

In UCONN_LLS_Reps_NoTreat there are six variables: Line, Replicate, Group, Condition, Treatment, and OLLS. These variables are defined below.

  • Line: Categorical variable with two levels, Ambient and HighTemp. Ambient line animals were from UConn lines held at 18C and HighTemp line animals were from UConn lines held at 22C.
  • Replicate: This categorical variable has four levels referring to which replicate line animals originated from.
  • Treatment: Categorical variable with two levels 18 and 22. Animals at 18 were held at 18C at the time of the upper lethal temperature assay. Animals at 22 were held at 22C at the time of the upper lethal temperature assay. 
  • Group: Six level categorical variable defining each unique combination of line and treatment.
  • Condition: This variable is redundant to Group, with a different naming scheme for analysis in R.
  • OLLS: Observed lower lethal salinity for each individual copepod.

In SalinityTemp there are three variables: Population, Salinity, and ULT.

  • Population: Categorical variable with two levels: HB, and UCONNControl. HB represents animals collected in Hammonasset Beach State Park, CT. UCONNControl represents animals from the UConn originating ambient line animals held at 18C.
  • Salinity: This is a categorical variable with three levels. Each level represents the salinity treatment copepods were exposed to in ppt.
  • ULT: This is a continuous variable representing the upper lethal temperature of each individual copepod.

LHS_ctmax_Complete is a dataset with six variables: Population, Plate, Stage, Ctmax, Sex, and MeanMax.

  • Population: Categorical variable with three levels: Maine, NewYork, and Florida.
  • Plate: Categorical variable with three levels, designating which six well plate animals were in.
  • Stage: Categorical variable with three levels: Adult, Copepodite, and Nauplii. These are the life history stages copepods were at when they were assessed for their upper lethal temperature.
  • Ctmax: This is a continuous variable with upper lethal temperature values for each individual copepod.
  • Sex: Categorical variable with three levels: Male, Female, and Unknown.
  • MeanMax: Mean maximum temperature collected from buoys near each population site.

In UCONN_GradualSalinity_Trial there are five variables: Line, Condition, Replicate, Sex, and LLS.

  • Line: Categorical variable with one level, Control. These represent animals that originated from UConn control line held at 18C.
  • Condition: This is a categorical variable with one level, High. This represents that the animals were held at 22C during the salinity trial.
  • Replicate: This is a categorical variable with one level, 2. This represents the replicate line the animals originated from.
  • Sex: Categorical variable with two levels: Male and Female. This represents the sex of the individual copepod in the salinity trial.
  • LLS: This is a continuous variable for the lower lethal salinity of each individual copepod.

Code/Software

Code can be found at this Github repository: https://github.com/lashlock/Developmental-Temperature-more-than-Long-Term-Evolution-Defines-Thermal-Tolerance

Funding

National Science Foundation