DOI: 10.5061/dryad.hdr7sqvtw
title: Trends in early larval traits of a global invader at home across a latitudinal gradient: The European shore crab <em>Carcinus maenas</em>

description: Aim: This study sets out to understand the variability in larval
 traits of dispersive life stages of a famous invader, the European shore
 crab Carcinus maenas, in its native distribution range.
 Location: North East Atlantic coast from the Norwegian Arctic to
 the southern European distribution limit of C. maenas in Southern Spain.
 Taxon: European shore crab Carcinus maenas (Crustacea, Decapoda).
 Methods: We quantified latitudinal patterns in larval body mass,
 elemental composition, and thermal tolerance of the first larval stage. We
 collected crabs from four populations spanning a 25° latitudinal gradient
 (Vigo in Northern Spain; Bergen, Trondheim and Bodø in Norway) and
 re-analysed published and unpublished data of body mass and elemental
 composition of additional populations from Germany, Wales, France, and
 Southern Spain. Furthermore, we used two laboratory experiments to test
 the thermal tolerance limits of the first larval stage from Vigo and the
 Norwegian populations. In the first experiment, we reared larvae from
 hatching to Zoea II at seven temperatures (9 – 27 °C) and from hatching to
 LT50 at 6 °C. In the second experiment, we exposed freshly hatched larvae
 to ramps of increasing or decreasing temperatures (up to 40 °C and down to
 3 °C). Results: Across the entire European range, we found a
 substantial increase in dry mass, and carbon and nitrogen content of
 freshly hatched larvae with latitude. Norwegian populations exhibited
 higher survival at 9 °C than the Vigo population. Furthermore, LT50 at 6
 °C increased from South to North. All populations showed high survival in
 the range 12 – 24 °C but low survival at 27 °C. Main
 conclusions: Larval tolerance quantified by using survival to
 Zoea II is not clearly related to the tolerance quantified with the ramp
 experiments, indicating that each method assesses different aspects of
 thermal tolerance. Tolerance to low temperature correlated positively to
 tolerance to high temperature, suggesting that variation among females in
 larval responses reflects a general physiological quality rather than
 trade-offs. We provide evidence for potentially adaptive variations in
 larval body mass and thermal tolerance across a latitudinal gradient for
 C. maenas.
description: We collected crabs from four populations (Vigo in Northern Spain;
 Bergen, Trondheim and Bodø in Norway). In two laboratory experiments we
 tested the thermal tolerance limits of the first larval stage from these
 populations. In the first experiment, we reared larvae from hatching to
 Zoea II at seven temperatures (9 – 27 °C) and from hatching to
 LT<sub>50</sub> at 6 °C. In the second experiment, we exposed
 freshly hatched larvae to ramps of increasing or decreasing temperatures
 (up to 40 °C and down to 3 °C). Further, we re-analyzed published and
 unpublished data on body mass and elemental composition of additional
 populations from Germany, Wales, France, and Southern Spain.
description: # Trends in early larval traits of a global invader at home across a
 latitudinal gradient: The European shore crab *Carcinus maenas*
 [https://doi.org/10.5061/dryad.hdr7sqvtw](https://doi.org/10.5061/dryad.hdr7sqvtw) ## Description of the data and file structure The dataset contains experimental data from four populations spanning a large latitudinal gradient. We collected crabs from four populations (Vigo in Northern Spain; Bergen, Trondheim and Bodø in Norway). In two laboratory experiments, we tested the thermal tolerance limits of the first larval stage from these populations. In the first experiment, we reared larvae from hatching to Zoea II at seven temperatures (9 – 27 °C) and from hatching to LT50 at 6 °C. In the second experiment, we exposed freshly hatched larvae to ramps of increasing or decreasing temperatures (up to 40 °C and down to 3 °C). In the associated publication, we re-analysed published and unpublished data on body mass and elemental composition of additional populations from Germany, Wales, France, and Southern Spain. We found evidence for potentially adaptive variations in larval body mass and thermal tolerance across a latitudinal gradient for *C. maenas*. Across the entire European range, we found a substantial increase in dry mass, and carbon and nitrogen content of freshly hatched larvae with latitude. Norwegian populations exhibited higher survival at 9 °C than the Vigo population. Similarly, LT50 at 6 °C increased from South to North. Larval tolerance quantified by using survival to Zoea II is not clearly related to the tolerance quantified with the ramp experiments, indicating that each method assesses different aspects of thermal tolerance. Tolerance to low temperature correlated positively to tolerance to high temperature, suggesting that variation among females in larval responses reflects a general physiological quality rather than trade-offs. Human or animal rights The data presented here complies with national (Germany) and international laws (guidelines from the directives 2010/63/EU of the European Parliament and of the Council of 22nd September 2010) on the protection of animals used for scientific purposes. In addition, this research complies with the European regulation (N° 511/2014) regarding access to genetic resources and the fair and equitable sharing of benefits arising from their utilization (Nagoya protocol). Authorisation to access Spanish genetic resources (*Carcinus maenas*): Ref. ESNC68, CSV: G ### Files and variables #### File: Carcinus_ZoeaII.zip **Description:**  The zipped folder contains five subfolders that each contain the data and R scripts to plot and analyze the data as done in the manuscript. **Body_mass_and_CN** This folder contains information on the body mass and elemental composition of freshly hatched larvae of *Carcinus maenas* from populations from the European Atlantic coast. The folder contains one data table and the R script used to analyze and plot the data. The data table contains original raw data on body mass and carbon and nitrogen content. The data from other populations previously published in the literature that was used to produce Fig. 3 in the associated publication cannot be shared here due to publishing rights, but can be found in the respective publications. * **body_mass_this_study.csv**, variables: LOCATION= Population of origin, Latitude = latitude in decimal degree (°N), FEM = female number, STAGE = life stage (FH = freshly hatched, M = megalopa), TEMP = hatching temperature (°C), SAL = salinity (PSU) at hatch, n = number of larvae per measurement, Nperc = nitrogen content (%), Cperc = carbon content (%), DW = dry mass (µg) per individual larvae * **Body_mass_obtained_in_this_study.Rmd,** R script to plot the data **Correlations** This folder contains information on the correlation coefficients between survival or duration of development and dry mass at hatching under chronic exposure to temperature. The folder contains five data tables, and the R script used to analyze and plot the data. * **correlations_data_CARCINUS.csv,** variables: ffem = female number, ftemp = temperature (°) of survival and development, fpop = population, survZii =survival rate (%) to zoea II, devZii = duration of development (days) to zoea II, CW = carapace width of mother (mm), intime = time in aquarium until hatch (days), dry_mass_by_fem = mean dry mass by female (µg per individual), carbon_by_fem_perc = mean carbon content by female (%), nitrogen_by_fem_perc = mean nitrogen content by female (%), hatch_T = Temprature (°C) at hatch, cold_mean_psurv = mean proportion of survivors at the end of the cold ramp, cold_mean_tsurv = transformed number of survivors at the end of the cold ramp (transformation to change 0 and 1, see script in folder Survival and development), cold_mean_lsurv = log transformed, cold_mean_lgsurv is log transformed proportions, cold_sd_psurv = is standard deviation (sd) of proportion transformed data, cold_sd_tsurv = cold_sd_tsurv is sd of log proportion transformed data, cold_sd_lsurv = cold_sd_lsurv standard deviation of log transformed mean, cold_sd_lgsurv = cold_sd_lgsurv standard deviation of log transformed proportions, heat_meanLD50 = mean of LT50 in the heat ramp, heat_sdLD50 = heat_sdLD50 standard deviations of the heatramps * **bodymass_for_correlations_zii.csv**, dry_mass_by_fem = mean dry mass by female (µg per individual larvae), carbon_by_fem_perc = mean carbon content by female ( %), nitrogen_by_fem_perc = mean nitrogen content by female ( %), ffem=female number, fpop = population, hatch_T = temperature of the water in which a hatch happened, CW =carapace width (mm), hatchdate, collection date, intime =time the berried females were held in aquaria before larvae hatched, experiment denominated whether a hatch was used in the experiments or only in the body mass and elemental composition analysis(n=no, y=yes) * **correlation_between_Surv_and_devo_and_dw_for_plot.csv**, all contained variables explained above * **correlations_CARCINUS.Rmd**, R script that contains code for data analysis and plotting **LT50** This folder contains information on data on average duration until mortality exceeds 50 % (LT50) under chronic exposure to 6°C. The folder contains one data table, and the R script used to analyse and plot the data. * **CARCINUSLT50_6degrees.csv,** population = population of origin, female = female number, region= region the population belongs to, days_to_50perc = mean number of days until 50 percent mortality was reached, days_to_4left = mean number of days until only 4 of 10 initial larvae were alive, all other contained variables explained above * **CARCINUS_LT50.Rmd,** R script that contains code for data analysis and plotting **Ramps** The dataset contains data on heat and cold ramp exposure. For the heatramp and LT50 temperature was quantified. For the coldramp, the average percentage of survivors at the end of the ramp (3°C) was quantified. Two plots and analyses provided based on averages: 1) level of population, 2) level of female * **Ramps_Carcinus_by_females.csv,** variables: cold_mean_psurv =mean proportion of survivors at the end of the cold ramp, cold_mean_tsurv =transformed number of survivors at the end of the cold ramp (transformation to change 0 and 1, see script in folder Survival and development), cold_mean_lsurv = cold_mean_lsurv, cold_mean_lgsurv is log transformed, cold_sd_psurv=is standard deviation (sd) of proportion transformed data, cold_sd_tsurv=cold_sd_tsurv is log proportion transformed, cold_sd_lsurv = cold_sd_lsurv standard deviation of log transformed mean, cold_sd_lgsurv = cold_sd_lgsurv standard deviation of log transformed proportions, heat_meanLD50 = mean of LT50 in the heat ramp, heat_sdLD50 = heat_sdLD50 standard deviations of the heatramps, heat_mean_LD50temp_at_death_by_tray = mean LD50 (first seen after death) averaged by tray, heat_meanLD50temp_before_death_by_tray=mean LD50 (last seen before death) averaged by tray, heat_se_LD50temp_at_death_by_tray = standard error of mean LD50 (first seen after death) averaged by tray, heat_seLD50temp_before_death_by_tray = standard error of mean LD50 (last seen before death) averaged by tray, other variables explained above. * **Ramps_Carcinus_by_population.csv,** all contained variables explained above * **integrated_ramps_CARCINUS_Zii.Rmd,** R script that contains code for data analysis and plotting A folder is contained within "Ramps" called "**raw data**". This folder contains the raw data for the cold and heat ramps as well as the Rscript that analyzed the data. * **cold_ramp_LD_50_raw.csv,** variables: ramp_type = ramp type (down_fast = cold ramp), tray = tray number, LD50time_at_death_by_tray = minutes until LD was reached, LD50temp_at_death_by_tray= degree (°C) when LD was reached, LD50time_before_death_by_tray = minutes at last measuremnt before LD was reached, LD50temp_before_death_by_tray = degree (°C) at last measuremnt before LD was reached, survivors_at_end_by_tray = number of larvae that survived the ramp, time_at_end = number of minutes until experiment was ended, temp_at_end = degree (°C) until experiment was ended, * **heat_ramp_LD_50_raw.csv**, variables: ramp_type = ramp type (up_fast = heat ramp), all other variables explained above. * **meanLDheatramp.csv**, variable: meanLD50 = mean LD 50 between the last check while larvae were still alive and the first check after they passed away, sdLD50 corresponding standard deviation, all other variables explained above. **Survival_and_development** Survival rates from hatch to the moult to the second stage Zoea II. Data provided as proportions but also transformed data available in the dataset. Duration of development until moult to Zoea II per temperature. The dataset also includes transformed data. * **Carcinus_2022_survival_development.csv,** survival_Zii is the proportion of survivors until moult to Zoea II starting with 10 larvae per replicate,development_Zii is the duration of development until Zoea II in days * **Survival_and_development_CARCINUS_Zii_2022.Rmd,** R script that contains code for data analysis and plotting ## Code/software All analyses were performed, and all plots were created using R version 4.3.2. All used packages are mentioned in the R scripts in the respective folders. All scripts included in the folders are annotated. ## Access information Other publicly accessible locations of the data used in the associated study, but not provided here: *  Occurrence data of *Carcinus maenas* was obtained from GBIF. GBIF. (2023). GBIF.org, Carcinus maenas  (21 November 2023) GBIF Occurrence Download [https://doi.org/10.15468/dl.aghsjj](https://doi.org/10.15468/dl.aghsjj). [https://doi.org/10.15468/dl.aghsjj](https://doi.org/10.15468/dl.aghsjj) *  All Sea surface temperatures were based on ten years of daily averaged SST generated using E.U. Copernicus Marine Service Information; [https://doi.org/10.48670/moi-00165](https://doi.org/10.48670/moi-00165) Literature data was derived from the following sources: *  Literature data of dry mass, carbon, and nitrogen content of freshly hatched larvae was extracted from the following research papers as well as unpublished data. An overview table is included in the supporting information of the manuscript. Anger K, Harms J (1990) Elemental (CHN) and proximate biochemical composition and decapod crustacean larvae. CBPB 97:69–80. [https://doi.org/10.1016/0305-0491(90)90180-2](https://doi.org/10.1016/0305-0491\(90\)90180-2) Anger K, Spivak E, Luppi T (1998) Effects of reduced salinities on development and bioenergetics of early larval shore crab, *Carcinus maenas*. Journal of Experimental Marine Biology and Ecology 220:287–304. [https://doi.org/10.1016/S0022-0981(97)00110-X](https://doi.org/10.1016/S0022-0981\(97\)00110-X) Dawirs RR (1980) Elemental composition (C,N,H) in larval and crab-I stages of *Pagurus bernhardus* (Decapoda, Paguridae) and *Carcinus maenas* (Decapoda, Portunidae). Mar Biol 57:17–23 Dawirs RR (1982) Methodical aspects of rearing decapod larvae, *Pagurus bernhardus* (Paguridae) and *Carcinus maenas *(Portunidae). Helgolander Meeresunters 35:439–464. [https://doi.org/10.1007/BF01999134](https://doi.org/10.1007/BF01999134) Dawirs RR (1987) Influence of limited starvation periods on growth and elemental composition (C,N,H) of *Carcinus maenas* (Decapoda: Portunidae) larvae reared in the laboratory. Mar Biol 93:543–549. [https://doi.org/10.1007/BF00392792](https://doi.org/10.1007/BF00392792) Dawirs RR (1986) Influence of limited food supply on growth and elemental composition (C, N, H) of *Carcinus maenas* (Decapoda) larvae, reared in the laboratory. Mar Ecol Prog Ser 31:301–308. [https://doi.org/10.3354/meps031301](https://doi.org/10.3354/meps031301) Harms J, Meyer-Harms B, Dawirs RR, Anger K (1994) Growth and physiology of *Carcinus maenas* (Decapoda, Portunidae) larvae in the field and in laboratory experiments. Mar Ecol Prog Ser 108:107–118. [https://doi.org/10.3354/meps108107](https://doi.org/10.3354/meps108107) Šargač Z, Giménez L, González-Ortegón E, et al (2022) Quantifying the portfolio of larval responses to salinity and temperature in a coastal-marine invertebrate: a cross population study along the European coast. Mar Biol 169:81:18. [https://doi.org/10.1007/s00227-022-04062-7](https://doi.org/10.1007/s00227-022-04062-7) Šargač Z, Giménez L, Harzsch S, et al (2021) Contrasting offspring responses to variation in salinity and temperature among populations of a coastal crab: A maladaptive ecological surprise? Mar Ecol Prog Ser 677:51–65. [https://doi.org/10.3354/meps13851](https://doi.org/10.3354/meps13851) Spitzner F, Giménez L, Meth R, et al (2019) Unmasking intraspecific variation in offspring responses to multiple environmental drivers. Mar Biol 166:112. [https://doi.org/10.1007/s00227-019-3560-y](https://doi.org/10.1007/s00227-019-3560-y) Torres G, Thomas DN, Whiteley NM, et al (2020) Maternal and cohort effects modulate offspring responses to multiple stressors. Proc R Soc B 287:20200492. [https://doi.org/10.1098/rspb.2020.0492](https://doi.org/10.1098/rspb.2020.0492)