Marine Disease Ecology Laboratory, Smithsonian Environmental Research Center, Edgewater, MD21037, USA.
Marine Invasions Research Laboratory, Smithsonian Environmental Research Center, Edgewater, MD21037, USA.
Parasitology. 2021 Apr;148(5):532-538. doi: 10.1017/S0031182020002383. Epub 2020 Dec 23.
Since the discovery of Perkinsus marinus as the cause of dermo disease in Crassostrea virginica, salinity and temperature have been identified as the main environmental drivers of parasite prevalence. However, little is known about how these variables affect the movement of the parasite from host to water column. In order to elucidate how environmental factors can influence the abundance of this parasite in the water column, we conducted a series of experiments testing the effects of time of day, temperature and salinity on the release of P. marinus cells from infected oysters. We found that P. marinus cells were released on a diurnal cycle, with most cells released during the hottest and brightest period of the day (12:00-18:00). Temperature also had a strong and immediate effect on the number of cells released, but salinity did not, only influencing the intensity of infection over the course of several months. Taken together, our results demonstrate that (1) the number of parasites in the water column fluctuates according to a diurnal cycle, (2) temperature and salinity act on different timescales to influence parasite abundance, and (3) live infected oysters may substantially contribute to the abundance of transmissive parasites in the water column under particular environmental conditions.
自从发现 Perkinsus marinus 是导致 Crassostrea virginica 出现皮疾病的原因以来，盐度和温度已被确定为寄生虫流行的主要环境驱动因素。然而，对于这些变量如何影响寄生虫从宿主转移到水柱中的运动，人们知之甚少。为了阐明环境因素如何影响水中这种寄生虫的丰度，我们进行了一系列实验，测试了时间、温度和盐度对感染牡蛎释放 P. marinus 细胞的影响。我们发现 P. marinus 细胞呈昼夜节律释放，大多数细胞在一天中最热和最亮的时间段（12:00-18:00）释放。温度对释放的细胞数量也有强烈而直接的影响，但盐度没有，仅在几个月的时间内影响感染强度。总的来说，我们的结果表明：(1) 水柱中的寄生虫数量根据昼夜节律波动；(2) 温度和盐度在不同的时间尺度上影响寄生虫丰度；(3) 在特定的环境条件下，活体感染的牡蛎可能会大大增加水柱中传染性寄生虫的丰度。
