Lipid content describing the behavior of coral larvae in high pCO2 within shallow tropical reefs in Okinawa, Japan from 2016-07 to 2016-08

<p>Twelve colonies of Pocillopora damicornis (Linnaeus 1758) were collected in July and August 2016 from ~ 1-m depth on a patch reef on the northwest shore of Okinawa (26°40’18.24” N, 127°53’4.78” E). Colonies were collected prior to expected larval release in Okinawa in July and August (S. Harii, unpublished data on the study site), with peak release occurring ~ 7 days after the new moon.<br />
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Following collection, colonies were transferred to Sesoko Station, part of the Tropical Biosphere Research Center University of the Ryukyus, where they were incubated outdoors in individual containers exposed to natural irradiance in flow-through seawater. Ambient seawater was pumped at 3.0 L min-1 (AC Flowmeter, Tokyo Keiso Co., Japan) from 4–5 m depth and stored in two 10 L reservoirs. Air was bubbled constantly in to the reservoirs at 3.0 L min-1 to maintain ambient seawater pCO2 (i.e., the control conditions). Seawater temperature was measured hourly at 1–2-m depth near the collection site prior to, and during, the experiment (HOBO Pro v2, Onset Computer Corporation, USA), and was 29.9 ± 0.2°C (mean ± SE, n = 45 days), with a daily minimum of 28.3°C and daily maximum of 31.8°C (R. Prasetia &amp; S. Harii, unpublished data) that reflects summertime diurnal warming in this location. Temperature in the containers holding the corals was maintained within this range during the experiment (29.8 ± &lt; 0.2°C, mean ± SE, n = 31) using a chiller (ZR-130E, Zensui, Japan).<br />
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Planulae released from P. damicornis during the first quarter moon of July and August were collected at ~ 05:00 hrs following their release at ~ 03:00 hrs, using containers lined with 110 µm plankton mesh. As larvae from P. damicornis are physiologically dissimilar among days of release, larvae were collected from the inferred day of peak release and pooled among colonies releasing larvae on this day. Larvae from July and August were used to test the effects of pCO2 (two levels) and depths (two levels) on larval behavior, and the experiment was conducted in two parts. The first part (July 2016) tested the effects of two pCO2 regimes on larval behavior with the tubes positioned with their upper opening adjacent to the air-water interface of the seawater (hereafter “shallow” tubes), and the second part (August 2016) tested the effects of the same two pCO2 regimes on larval behavior with the tubes positioned with their upper opening ~3–4 m below the surface (hereafter “deep” tubes).</p>

2016年7月至8月，研究人员于冲绳西北岸一处斑礁（北纬26°40’18.24”，东经127°53’4.78”）约1米水深处，采集了12株鹿角杯形珊瑚（*Pocillopora damicornis*，Linnaeus 1758）群体。本次采集恰逢冲绳地区7-8月预期的浮浪幼虫释放期之前（S. Harii，该研究样地未公开数据），而该区域的幼虫释放峰值通常出现在新月后约7天。

采集完成后，所有珊瑚群体被转移至琉球大学热带生物圈研究中心下属的濑高实验站（Sesoko Station），随后置于户外独立容器中，于流通海水中接受自然光照培养。实验用海水从4-5米水深处以每分钟3.0升的流速（AC型流量计，东京计装株式会社，日本）抽取，并储存在两个10升的储水罐中。以每分钟3.0升的速率持续向储水罐通入空气，以维持环境海水的二氧化碳分压（pCO₂），即对照组条件。实验前后及实验期间，研究人员在采样点附近1-2米水深处每小时记录一次海水温度（HOBO Pro v2型数据记录仪，美国Onset计算机公司），记录显示水温为29.9±0.2℃（平均值±标准误，SE，n=45天），日最低温28.3℃，日最高温31.8℃（R. Prasetia & S. Harii，未公开数据），该温度波动反映了该区域夏季的日间升温现象。实验过程中，通过ZR-130E型冷水机（Zensui株式会社，日本）将珊瑚饲养容器内的水温维持在该范围内（29.8±<0.2℃，平均值±标准误，SE，n=31）。

2016年7月及8月的上弦月期间，鹿角杯形珊瑚释放的浮浪幼虫（Planulae）于每日约03:00时释放后，在约05:00时使用衬有110µm浮游生物网的容器进行收集。由于鹿角杯形珊瑚的幼虫在不同释放日的生理特征存在差异，研究人员仅收集峰值释放日的幼虫，并将当日释放幼虫的所有珊瑚群体的幼虫混合。本次实验分别利用7月和8月收集的幼虫，测试二氧化碳分压（两个水平）与水深（两个水平）对幼虫行为的影响，实验分为两个阶段：第一阶段（2016年7月）测试两种二氧化碳分压条件对幼虫行为的影响，此时培养管的上端开口紧邻海水气水界面，即"浅管"组；第二阶段（2016年8月）测试相同的两种二氧化碳分压条件对幼虫行为的影响，此时培养管的上端开口位于海面下约3-4米处，即"深管"组。