Seawater carbonate chemistry and larval feeding efficiency and change food selectivity in the mollusk Concholepas concholepas@en

We present experimental data obtained from an experiment with newly hatched veliger larvae of the gastropod Concholepas concholepas exposed to three pCO2 levels. Egg capsules were collected from two locations in northern and central Chile, and then incubated throughout their entire intra-capsular life cycle at three nominal pCO2 levels, 400, 700 and 1000 ppm (i.e. corresponding to 8.0, 7.8 and 7.6 pH units, respectively). Hatched larvae were fed with natural food assemblages. Food availability at time zero did not vary significantly with pCO2 level. Our results clearly showed a significant effect of elevated pCO2 on the intensity of larval feeding, which dropped by >60%. Incubation also showed that pCO2-driven ocean acidification (OA) may radically impact the selectivity of ingested food by C. concholepas larvae. Results also showed that larvae switched their clearance rate based on large cells, such as diatoms and dinoflagellates to tiny and highly abundant nanoflagellates and cyanobacteria as pCO2 levels increased. Thus, this study reveals the important effect of low pH conditions on larval feeding behavior, in terms of both ingestion magnitude and selectivity. These findings support the notion that larval feeding is a key physiological process susceptible to the effects of OA.本研究报道了一项针对智利腹足类Concholepas concholepas新孵化面盘幼虫（veliger larvae）的实验所得实测数据，该实验将幼虫暴露于三种二氧化碳分压（pCO2）水平中。研究人员从智利北部与中部的两个采样点采集卵囊，随后将其置于三种标称二氧化碳分压水平（400、700与1000 ppm，分别对应pH 8.0、7.8与7.6）下，完成整个囊内生命周期的培养。孵化后的幼虫以天然食物组合为饵料，实验初始时刻的食物可获得性未随二氧化碳分压水平出现显著差异。实验结果清晰表明，升高的二氧化碳分压对幼虫摄食强度具有显著负面影响，摄食强度下降幅度超过60%。本次培养实验同时显示，由二氧化碳分压升高驱动的海洋酸化（Ocean Acidification, OA）可显著影响Concholepas concholepas幼虫对摄食食物的选择性。实验结果还显示，随着二氧化碳分压水平升高，幼虫的摄食清滤率偏好从以硅藻（diatoms）、甲藻（dinoflagellates）等大型细胞为摄食对象，转变为以丰度极高的微型鞭毛虫（nanoflagellates）与蓝细菌（cyanobacteria）为摄食对象。因此，本研究揭示了低pH环境对幼虫摄食行为的重要影响，涉及摄食强度与食物选择性两个维度。上述研究结果支持“幼虫摄食是易受海洋酸化影响的关键生理过程”这一学术观点。