Bernard Guillaume, Duchêne Jean-Claude, Romero-Ramirez Alicia, Lecroart Pascal, Maire Olivier, Ciutat Aurélie, Deflandre Bruno, Grémare Antoine
Univ. Bordeaux, EPOC, UMR 5805, F33400, Talence, France.
Tvärminne zoological station, University of Helsinki, Hanko, Finland.
PLoS One. 2016 Apr 26;11(4):e0154270. doi: 10.1371/journal.pone.0154270. eCollection 2016.
The effects of temperature and food addition on particle mixing in the deposit-feeding bivalve Abra alba were assessed using an experimental approach allowing for the tracking of individual fluorescent particle (luminophore) displacements. This allowed for the computations of vertical profiles of a set of parameters describing particle mixing. The frequency of luminophore displacements (jumps) was assessed through the measurement of both waiting times (i.e., the time lapses between two consecutive jumps of the same luminophore) and normalized numbers of jumps (i.e., the numbers of jumps detected in a given area divided by the number of luminophores in this area). Jump characteristics included the direction, duration and length of each jump. Particle tracking biodiffusion coefficients (Db) were also computed. Data originated from 32 experiments carried out under 4 combinations of 2 temperature (Te) and 2 food addition (Fo) levels. For each of these treatments, parameters were computed for 5 experimental durations (Ed). The effects of Se, Fo and Ed were assessed using PERmutational Multivariate ANalyses Of VAriance (PERMANOVAs) carried out on vertical depth profiles of each particle mixing parameter. Inversed waiting times significantly decreased with Ed whereas the normalized number of jumps did not, thereby suggesting that it constitutes a better proxy of jump frequency when assessing particle mixing based on the measure of individual particle displacements. Particle mixing was low during autumn temperature experiments and not affected by Fo, which was attributed to the dominant effect of low temperature. Conversely, particle mixing was high during summer temperature experiments and transitory inhibited by food addition. This last result is coherent with the functional responses (both in terms of activity and particle mixing) already measured for individual of the closely related clam A. ovata originating from temperate populations. It also partly resulted from a transitory switch between deposit- and suspension-feeding caused by the high concentration of suspended particulate organic matter immediately following food addition.
采用一种能够追踪单个荧光颗粒（发光体）位移的实验方法，评估了温度和添加食物对沉积食性双壳贝类白樱蛤（Abra alba）颗粒混合的影响。这使得能够计算出一组描述颗粒混合的参数的垂直剖面。通过测量等待时间（即同一发光体两次连续跳跃之间的时间间隔）和归一化跳跃次数（即在给定区域检测到的跳跃次数除以该区域的发光体数量）来评估发光体位移（跳跃）的频率。跳跃特征包括每次跳跃的方向、持续时间和长度。还计算了颗粒追踪生物扩散系数（Db）。数据来自在2个温度（Te）和2个食物添加（Fo）水平的4种组合下进行的32次实验。对于这些处理中的每一种，在5个实验持续时间（Ed）下计算参数。使用基于每个颗粒混合参数的垂直深度剖面进行的置换多变量方差分析（PERMANOVA）来评估Se、Fo和Ed的影响。反转的等待时间随Ed显著减少，而归一化跳跃次数则不然，因此表明在基于单个颗粒位移测量评估颗粒混合时，它是跳跃频率的更好代表。秋季温度实验期间颗粒混合较低，且不受Fo影响，这归因于低温的主导作用。相反，夏季温度实验期间颗粒混合较高，且添加食物会暂时抑制颗粒混合。这一结果与已经针对来自温带种群的密切相关的卵形蛤（A. ovata）个体测量的功能反应（在活动和颗粒混合方面）一致。这也部分是由于添加食物后立即出现的高浓度悬浮颗粒有机物导致从沉积摄食到悬浮摄食的暂时转变所致。
