This is data from a laboratory experiment in which snow crab juveniles were held at three different pHs (ambient, pH 7.8, and pH 7.5). Growth, survival, and morphology were recorded. The complete methods, which should be read and understood prior to using this data, are under review as: Long, W.C. (In Review). Ocean acidification reduces juvenile snow crab, Chionoecetes opilio, survival but does not affect growth or morphometrics.

In this study, we reared red king crab larvae from hatching to the first crab stage in four different pH treatments: current surface ambient, diel fluctuation to mimic larval migration between the surface and mixed layer under current ambient conditions, pH 7.8, and pH 7.5. Larvae were monitored throughout development and the average length of each stage was determined. At each of the zoeal stages, the glaucothoe stage, and the first crab stage, we measured survival, morphometry, dry mass, and carbon, nitrogen, calcium, and magnesium content.This dataset is included in the OA-ICC data compilation maintained in the framework of the IAEA Ocean Acidification International Coordination Centre (see https://oa-icc.ipsl.fr). Original data were downloaded from NOAA National Centers for Environmental Information (see Source) by the OA-ICC data curator. In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2024) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2024-06-24.

This dataset is a supplement to the paper: Long, W.C., Daly, B.J., Cummiskey, P.A., 2024. Optimizing release strategies for red king crab stock enhancement: Effects of release timing. Fisheries Research 274, 106975. https://doi.org/https://doi.org/10.1016/j.fishres.2024.106975. The published paper contains a full description of the experimental design and sampling protocols and this data set can only be interpreted in light of the information presented there. Following is a list of the spreadsheets and metadata for individual columns:
Common to many sheets: These columns are used in multiple sheets.Date- date of observation in mm/dd/yyyy formatPlot- Alphabetical character designating a single experimental plotTreatment- Release month of crabs for the particular plot. Control plots did not have any crab released in them.I/O- Designates whether the observation was made inside a plot (I) or outside along the edge of a plot (O)Depth- Depth in feet at the time of observation (yes, I know it’s not SI but it’s what our US made dive gauges read in so you get the raw data!)
Crab_CW.csv: This sheet contains measurements of crabs for each release and experimentEvent- We released crabs at 3 time periods (Release 1-3) and did 3 tethering experiments (Tethering 1-3).CW- The carapace width of each crab (including spines) in millimeters
Quadrate_Counts.csv: This sheet contains data on red king crab counts in quadratsCover- the estimated percent cover of structure forming biota (primarily macroalgae) in the quadratRKC- the number of year-0 red king crab juveniles found in the quadrat
Quadrate_Preds.csv: This sheet contains the counts of potential predators in quadrat counts. This is the data as analyzed; each row represents the sum of individuals counted in 3 replicate quadrates inside or outside a plot on a single day. Species encountered are indicated to the lowest taxonomic level possible as column headers. Hermit crabs were the only composite species group; see paper for details.
Substrate.csv: This sheet contains data on substrate in each plot recorded once per plot during the season. Substrate types are indicated as column labels and numbers are the estimated percent cover of each. Rock, gravel, shell, sand, and mud sum to 100%.
Tethering.csv: This sheet contains observations on tethered crabs in plots.Date deployed- the date (dd/mm/yyyy) the crabs were initially deployedTime deployed- the time (local, Alaska Daylight Time, 24h format) the crabs were initial deployedNumber out- the number of crabs tethered in each plotFirst check time- the time (local, Alaska Daylight Time, 24h format) crabs were checked- this is on the same day as deploymentFirst check number- the number of crabs still alive and on their tethered (not eaten or molted) at the first check2nd check time- the time (local, Alaska Daylight Time, 24h format) crabs were checked- this is on the day after deployment2nd check number- the number of crabs still alive and on their tethered (not eaten or molted) at the second checkNotes- Important notes on molting and tether failures
Quadrate_Preds.csv: This sheet contains the counts of potential predators in transects. Species encountered are indicated to the lowest taxonomic level possible as column headers. Sculpins (Cottoidea spp.) were separated into adults and juveniles.

This dataset is a supplement to the paper: Long, W.C., Daly, B.J., Cummiskey, P.A., 2024. Optimizing release strategies for red king crab stock enhancement: Effects of release timing. Fisheries Research 274, 106975. https://doi.org/https://doi.org/10.1016/j.fishres.2024.106975. The published paper contains a full description of the experimental design and sampling protocols and this data set can only be interpreted in light of the information presented there. Following is a list of the spreadsheets and metadata for individual columns:
Common to many sheets: These columns are used in multiple sheets.Date- date of observation in mm/dd/yyyy formatPlot- Alphabetical character designating a single experimental plotTreatment- Release month of crabs for the particular plot. Control plots did not have any crab released in them.I/O- Designates whether the observation was made inside a plot (I) or outside along the edge of a plot (O)Depth- Depth in feet at the time of observation (yes, I know it’s not SI but it’s what our US made dive gauges read in so you get the raw data!)
Crab_CW.csv: This sheet contains measurements of crabs for each release and experimentEvent- We released crabs at 3 time periods (Release 1-3) and did 3 tethering experiments (Tethering 1-3).CW- The carapace width of each crab (including spines) in millimeters
Quadrate_Counts.csv: This sheet contains data on red king crab counts in quadratsCover- the estimated percent cover of structure forming biota (primarily macroalgae) in the quadratRKC- the number of year-0 red king crab juveniles found in the quadrat
Quadrate_Preds.csv: This sheet contains the counts of potential predators in quadrat counts. This is the data as analyzed; each row represents the sum of individuals counted in 3 replicate quadrates inside or outside a plot on a single day. Species encountered are indicated to the lowest taxonomic level possible as column headers. Hermit crabs were the only composite species group; see paper for details.
Substrate.csv: This sheet contains data on substrate in each plot recorded once per plot during the season. Substrate types are indicated as column labels and numbers are the estimated percent cover of each. Rock, gravel, shell, sand, and mud sum to 100%.
Tethering.csv: This sheet contains observations on tethered crabs in plots.Date deployed- the date (dd/mm/yyyy) the crabs were initially deployedTime deployed- the time (local, Alaska Daylight Time, 24h format) the crabs were initial deployedNumber out- the number of crabs tethered in each plotFirst check time- the time (local, Alaska Daylight Time, 24h format) crabs were checked- this is on the same day as deploymentFirst check number- the number of crabs still alive and on their tethered (not eaten or molted) at the first check2nd check time- the time (local, Alaska Daylight Time, 24h format) crabs were checked- this is on the day after deployment2nd check number- the number of crabs still alive and on their tethered (not eaten or molted) at the second checkNotes- Important notes on molting and tether failures
Quadrate_Preds.csv: This sheet contains the counts of potential predators in transects. Species encountered are indicated to the lowest taxonomic level possible as column headers. Sculpins (Cottoidea spp.) were separated into adults and juveniles.

In this study, we examined how CO2-driven acidification affected larval survival and condition in red king crab (Paralithodes camtschatica), an important fishery species in Alaska. Experiments on the effects of reduced pH on morphology; survival; growth rate; mass; and Ca, Mg, C, and N contents of the larvae were conducted at 4 larval pH treatment. The complete methods, which should be read and understood prior to using this data, are under review and are published as a preprint as: Long, W.C., Gardner, J.L., Conrad, A., Foy, R., 2023. Effects of ocean acidification on red king crab larval survival and development. bioRxiv, 2023.2010. 2002.560246. https://doi.org/10.1101/2023.10.02.560246

In this study, we examined how CO2-driven acidification affected the embyro development and hatching of snow crab (Chionoecetes opilio), an important fishery species in Alaska. Ovigerous females were held in one of three treatments: ambient pH (~8.1), pH 7.8, and pH 7.5, through two annual reproductive cycles. Morphometric changes during development and hatching success were measured for embryos both years and calcification was measured for the adult females at the end of the 2-year experiment. We also examined how CO2-driven acidification affected larval survival and condition in snow crab (Chionoecetes opilio). Experiments on the effects of reduced pH on morphology; starvation survival; mass; and Ca, Mg, C, and N contents of the larvae were conducted in a design that fully crossed maternal treatment (pH at which the ovigerous females were held during embryo development) and larval treatment (which were the same 3 pH treatments).

Ocean acidification (OA) adversely affects a broad range of marine calcifying organisms. Crustaceans, however, exhibit mixed responses to OA, with growth or survival negatively affected in some species, but unaffected or positively affected in others. In crustaceans, the mineralized cuticle resists mechanical loads, provides protection from the environment, and enables mobility, but little is known about how OA or interactions between OA and temperature affect its structure or function. Here, the effects of OA on the mechanics, structure, and composition of the cuticle in two Alaska king crab species was assessed. Juvenile blue king crabs (Paralithodes platypus) were exposed for a year to three pH levels, 8.1 (ambient), 7.8 and 7.5. Juvenile red king crabs (Paralithodes camtschaticus) were exposed for ~ 6 months to two pH levels, 8.0 and 7.8, at three temperatures: ambient, ambient + 2 °C, and ambient + 4 °C. Cuticle microhardness (a measure of resistance to permanent or plastic mechanical deformation), thickness, ultrastructure, and elemental composition were assessed in two body regions, the carapace and the crushing chela (claw). In both species tested, OA reduced endocuticle microhardness in the chela, but not in the carapace. There was no effect of pH or temperature on total procuticle thickness of the chela or carapace in either species. Reductions in microhardness were not driven by reduced calcium content of the shell. In fact, calcium content was significantly elevated in the carapace of blue king crabs and in the chela of red king crabs exposed to lower than ambient pH at ambient temperature, suggesting that calcium content alone is not a sufficient proxy for mechanical properties. Reduced chela microhardness, indicative of more compliant material, could compromise the utility of crushing chelae in feeding and defense.

Ocean acidification can affect the ability of calcifying organisms to build and maintain mineralized tissue. In decapod crustaceans, the exoskeleton is a multilayered structure composed of chitin, protein, and mineral, predominately magnesian calcite or amorphous calcium carbonate (ACC). We investigated the effects of acidification on the exoskeleton of mature (post-terminal-molt) female southern Tanner crabs, Chionoecetes bairdi. Crabs were exposed to one of three pH levels—8.1, 7.8, or 7.5—for two years. Reduced pH led to a suite of body-region-specific effects on the exoskeleton. Microhardness of the claw was 38% lower in crabs at pH 7.5 compared with those at pH 8.1, but carapace microhardness was unaffected by pH. In contrast, reduced pH altered elemental content in the carapace (reduced calcium, increased magnesium), but not the claw. Diminished structural integrity and thinning of the exoskeleton was observed at reduced pH in both body regions; internal erosion of the carapace was present in most crabs at pH 7.5, and the claws of these crabs showed substantial external erosion, with tooth-like denticles nearly or completely worn away. Using infrared spectroscopy, we observed a shift in the phase of calcium carbonate present in the carapace of pH-7.5 crabs: a mix of ACC and calcite was found in the carapace of crabs at pH 8.1, whereas the bulk of calcium carbonate had transformed to calcite in pH-7.5 crabs. With limited capacity for repair, the exoskeleton of long-lived crabs that undergo a terminal molt, such as C. bairdi, may be especially susceptible to ocean acidification.

We examined the effect of long-term (2 year) exposure to decreased seawater pH (7.8 and 7.5, PCO2 ~ 760 and 1550 µatm, respectively) on exoskeletal properties in post-terminal-molt female Chionoecetes opilio. Since the effects of OA vary among body regions in decapods, exoskeletal properties (microhardness, thickness, and elemental composition) were measured in five body regions: the carapace, both claws, and both third walking legs.

In this study, we examined how CO2-driven acidification affected the growth and survival of juvenile golden king crab (Lithodes aequispinus), an important fishery species in Alaska. Juveniles were reared from larvae in surface ambient pH seawater at the Kodiak Laboratory. Newly molted early benthic instar crabs were randomly assigned to one of three pH treatments: (1) surface ambient pH ~ 8.2, (2) likely in situ ambient pH 7.8, and (3) pH 7.5. Thirty crabs were held in individual inserts in each treatment for 127 days and checked daily for molting or death. The complete methods, which should be read and understood prior to using this data, are published as: Long, W. C., Swiney, K. M., & Foy, R. J. (2021). Effects of ocean acidification on young of the year golden king crab (Lithodes aequispinus) survival and growth. Marine Biology, 168(8), 126. https://doi.org/10.1007/s00227-021-03930-y.