Interactive effects of near-future temperature increase (28/31°C) and ocean acidification (7.8/8.1 pH) on physiology and gonad development in adult Pacific sea urchin, Echinometra sp. A (NERP TE 5.2, AIMS)

This experiment grew adult Echinometra sp. A sea urchins under four temperature and pH treatments 28 / 7.9, 28 / 8.1, 31 / 7.9, 31 / 8.1 (degrees C, pH) to investigate the interactive effects of warming and acidification on their physiology. These treatments were chosen to match those that may be experienced in the near-future (2100) due to climate change. Each treatment was replicated across 3 aquaria, each with 6 individuals for a total of 72 sea urchins.

Method:

The adult Echinometra sp. A used in this experiment (32–54 mm diameter, 16–68 g wet weight) were collected on the 7th of September 2011 at 2–5 m water depth at Rib Reef (146 deg 52.49’ E, 18 deg 28.86’ S), a midshelf reef in the central section of the Great Barrier Reef. They represent 'intermediate-sized' adult animals at Rib Reef, omitting the smallest and largest specimens. The experiment started three weeks after individuals were collected.

The growth rate of the urchins was measured over 70 days and expressed as a percentage increase of the original weight. Sea urchins were placed into the aquaria on the 21 September 2011 (Day 0) and feed over the life of the experiment on brown macroalgae and coral rubble encrusted with crustose coralline algae was offered as an additional food source.

To reduce the influence of gut contents on weight measurements were taken after a 24 hour starvation period. The six individuals in each aquarium were distinguished based on colour patterns and size, which allowed each of their individual growth rates to be measured.

At the end of the experiment (Day 77) all Echinometra sp. A were dissected and the coelomic fluid carefully drained and its pH measured. The gonads were dried, weighed and sections were examined.

The experiment and its results are described in more detail in:
S. Uthicke, M. Liddy, H. D. Nguyen, M. Byrne (2014), Interactive effects of near-future temperature increase and ocean acidification on physiology and gonad development in adult Pacific sea urchin, Echinometra sp. A,. Coral Reefs. DOI 10.1007/s00338-014-1165-y

Data Dictionary:

Echinometra_Growth_righting.csv:
- wt_weight_initial: Initial wet weight (grams) of the sea urchins after blotting on day 1 after 24 hour starvation.
- diameter_initial: Initial diameter (mm) after blotting on day 1 after 24 hour starvation.
- wt_weight_final: Final wet weight (grams) after 70 days of treatment
- diameter_final: Final diameter (mm) after 70 days of treatment
- righting time: Time (seconds) for the individual to right itself after being turned upside down on day 10
- weight difference: Difference between the weight before and after 70 days of treatment
- growth_perc_BW: Percentage change in the weight
- diameter difference: Change in the diameter of each individual after 70 days of treatment.
- Aquaria: ID of the aquarium that each sea urchin was kept in.
- N_pH-temp: Number of pH and temperature measurements
- Temp_real: Average of measured temperatures of the aquarium over the experimental period. These were measured manually on most days (N=55) to confirm the performance of the automated temperature control.
- SD_Temp_real: Standard deviation of the measured temperatures.
- pH_real: Average of the measured pH of the aquarium over the experimental period. These were manually measured using a temperature-corrected pH meter (OAKTON, USA) and pH probe (EUTECH, USA).
- SD_pH_real: Standard deviation of the measured pH.

Echinometra_Gonad Index_noNA_actual_temps_ph.csv:
- Treat: Temperature / pH treatment
- Aquarium: ID of the aquarium
- Urchin No: Number of the sea urchin in each tank
- Sex: m - male, f - female
- Temp: Temperature treatment (degrees)
- pH: pH treatment
- Test_diam: (cm) final diameter (mm) after blotting on day 1 after 24 hour starvation
- Drained_wt with tray: Final wet weight (grams) after 70 days of treatment, including weight of tray
- Gonad_wet_wt_w_tray: : Wet weight of the dry gonad plus the measuring tray.
- Test_wt_weight: test-weight after subtracting tray weight.
- Gonad_wt_weight: Gonad wet weight after subtracting measuring tray weight.
- GI_wet: gonad index (the gonad weight as a percentage of total wet weight )
- Gonad_dry total wt: Weight of the dry gonad plus the measuring tray.
- Gonad_tray_wt: Weight of the measuring tray used to weight the dry gonads
- Gonad_dry_wt: Weight of the dry gonad (grams) after extraction and oven drying for 48 hours at 60 degrees C. (Gonad_dry total wt-Gonad_tray_wt)
- Test_dry_weight: Weight of the urchin test in grams (Test_dry_with_tray - Tray_wt)
- GI_dry: gonad index (gonad weight expressed as % of total dry weight)
- Test_dry_with_tray: Weight of the urchin test + weight of the tray (grams)
- Tray_wt: Weight of the tray used to take measurements of Test_dry_with_tray.
- CF_pH: pH in coelomic fluid measured within 2 min of the dissection.
- Gonad_dry_5 gonads: total gonad weight extrapolated to 5 gonads (only 3 were weighed for other measures because tissues were kept for other purposes)
- GI_5_gonads_dry: total gonad weight extrapolated to 5 gonads (only 3 were weighed for other measures because tissues were kept for other purposes)
- Temp_real: Average of measured temperatures of the aquarium over the experimental period. These were measured manually on most days (N=55) to confirm the performance of the automated temperature control.
- pH_real: Average of the measured pH of the aquarium over the experimental period. These were manually measured using a temperature-corrected pH meter (OAKTON, USA) and pH probe (EUTECH, USA).

本实验将成年艾氏棘球海胆（Echinometra sp. A）置于4组温度与pH条件下培养，条件分别为28℃/7.9、28℃/8.1、31℃/7.9、31℃/8.1，以探究气候变暖和海洋酸化对其生理的交互影响。上述实验条件的选取参照了气候变化下2100年近未来海洋可能出现的环境参数。每组实验设置3个重复水族箱，每个水族箱投放6只海胆，总计72只实验个体。

方法：
本实验所用的成年艾氏棘球海胆（Echinometra sp. A，壳径32~54 mm，湿重16~68 g）于2011年9月7日采集自大堡礁中部陆架礁Rib Reef（东经146°52.49′，南纬18°28.86′），水深2~5 m。采集个体为该礁区的“中等体型”成体，剔除了最小和最大的标本。实验于个体采集三周后启动。
实验周期为70天，以初始体重的百分比增长作为海胆的生长速率指标。2011年9月21日（实验第0天）将海胆放入水族箱，实验全程投喂褐藻（brown macroalgae），并额外提供附着有壳状珊瑚藻（crustose coralline algae）的珊瑚碎石作为补充食物源。
为消除消化道内含物对体重测量的影响，体重测量前需将海胆禁食24小时。每个水族箱内的6只个体可通过体色图案和体型大小进行区分，以此实现单只海胆生长速率的测定。
实验结束时（第77天），对所有艾氏棘球海胆进行解剖，小心抽取体腔液（coelomic fluid）并测定其pH。将生殖腺（gonads）烘干称重，并制作切片进行观察分析。
本实验及其研究结果的详细描述参见：
S. Uthicke、M. Liddy、H. D. Nguyen、M. Byrne (2014)，《近未来升温与海洋酸化对太平洋成年海胆Echinometra sp. A生理及性腺发育的交互影响》，《珊瑚礁》（Coral Reefs）。DOI: 10.1007/s00338-014-1165-y

数据字典：
1. Echinometra_Growth_righting.csv：
- wt_weight_initial：海胆经24小时禁食后，于第1天吸干体表水分后的初始湿重（单位：克）
- diameter_initial：海胆经24小时禁食后，于第1天吸干体表水分后的初始壳径（单位：毫米）
- wt_weight_final：经70天实验处理后的最终湿重（单位：克）
- diameter_final：经70天实验处理后的最终壳径（单位：毫米）
- righting time：实验第10天将海胆倒置后，其翻正耗时（单位：秒）
- weight difference：70天实验处理前后的体重差值
- growth_perc_BW：体重百分比变化量
- diameter difference：70天实验处理后个体壳径的变化量
- Aquaria：每只海胆所属水族箱的编号
- N_pH-temp：温度与pH测量次数
- Temp_real：实验周期内水族箱实测温度的平均值。实验期间多数天数（N=55）进行人工测量，以验证自动控温系统的运行效果
- SD_Temp_real：实测温度的标准差
- pH_real：实验周期内水族箱实测pH的平均值。采用经温度校正的pH计（OAKTON，美国）及pH探头（EUTECH，美国）进行人工测量
- SD_pH_real：实测pH的标准差

2. Echinometra_Gonad Index_noNA_actual_temps_ph.csv：
- Treat：温度/pH实验处理组
- Aquarium：水族箱编号
- Urchin No：每个养殖箱内海胆的编号
- Sex：性别，m为雄性，f为雌性
- Temp：温度处理条件（单位：摄氏度）
- pH：pH处理条件
- Test_diam：（单位：厘米）经24小时禁食、吸干体表水分后，于第1天测得的最终壳径（原数据标注存在毫米与厘米单位冲突）
- Drained_wt with tray：70天实验处理后的最终湿重（含称量托盘重量，单位：克）
- Gonad_wet_wt_w_tray：烘干前的生殖腺湿重（含称量托盘重量）
- Test_wt_weight：扣除托盘重量后的壳重
- Gonad_wt_weight：扣除称量托盘重量后的生殖腺湿重
- GI_wet：生殖腺指数（gonad index，以湿重计，即生殖腺重量占总湿重的百分比）
- Gonad_dry total wt：烘干后的生殖腺总重量（含称量托盘重量）
- Gonad_tray_wt：用于称量烘干生殖腺的托盘重量
- Gonad_dry_wt：生殖腺干重（单位：克），为解剖提取后于60℃烘箱烘干48小时所得，计算公式为 Gonad_dry total wt - Gonad_tray_wt
- Test_dry_weight：海胆壳的干重（单位：克），计算公式为 Test_dry_with_tray - Tray_wt
- GI_dry：生殖腺指数（gonad index，以干重计，即生殖腺重量占总干重的百分比）
- Test_dry_with_tray：海胆壳+称量托盘的总重量（单位：克）
- Tray_wt：用于称量Test_dry_with_tray的托盘重量
- CF_pH：解剖后2分钟内测得的体腔液（coelomic fluid）pH值
- Gonad_dry_5 gonads：按5个生殖腺推算的总干重（因部分组织留作他用，仅称量了3个生殖腺用于其他指标测定）
- GI_5_gonads_dry：按5个生殖腺推算的干重生殖腺指数（因部分组织留作他用，仅称量了3个生殖腺用于其他指标测定）
- Temp_real：实验周期内水族箱实测温度的平均值。实验期间多数天数（N=55）进行人工测量，以验证自动控温系统的运行效果
- pH_real：实验周期内水族箱实测pH的平均值。采用经温度校正的pH计（OAKTON，美国）及pH探头（EUTECH，美国）进行人工测量