School of Marine and Atmospheric Sciences, Stony Brook University, 239 Montauk HWY, Southampton, NY 11968, USA.
University of California Santa Cruz, 1156 High Street Santa Cruz, CA 95064, USA.
Harmful Algae. 2022 Jun;115:102236. doi: 10.1016/j.hal.2022.102236. Epub 2022 Apr 18.
The Asian clam (Corbicula fluminea) and eastern oyster (Crassostrea virginica) are important resource bivalves found in and downstream of waterways afflicted with cyanobacterial harmful algae blooms (CHABs), respectively. This study examined the potential for C. fluminea and C. virginica to become vectors of the hepatotoxin, microcystin, from the CHAB Microcystis. Laboratory experiments were performed to quantify clearance rates, particle selection, and accumulation of the hepatotoxin, microcystin, using a microcystin-producing Microcystis culture isolated from Lake Erie (strain LE-3) and field experiments were performed with water from Microcystis blooms in Lake Agawam, NY, USA. Clearance rates of Microcystis were faster (p<0.05) than those of Raphidocelis for C. fluminea, while C. virginica cleared Microcystis and Tisochrysis at similar rates. For both bivalves, clearance rates of bloom water were slower than cultures and clams displayed significantly greater electivity for green algae compared to wild populations of cyanobacteria in field experiments while oysters did not. In experiments with cultured Microcystis comprised of single and double cells, both bivalves accumulated >3 µg microcystins g (wet weight) in 24 - 72 h, several orders of magnitude beyond California guidance value (10 ng g ) but accumulated only up to 2 ng microcystins g when fed bloom water dominated by large Microcystis colonies for four days. For Asian clams, clearance rates and tissue microcystin content decreased when exposed to toxic Microcystis for 3 - 4 days. In contrast, eastern oysters did not depurate microcystin over 3 - 4-day exposures and accumulated an order of magnitude more microcystin than clams. This contrast suggests Asian clams are likely to accumulate minor amounts of microcystin by reducing clearance rates during blooms of Microcystis, selectively feeding on green algae, and depurating microcystin whereas oysters are more likely to accumulate microcystins and thus are more likely to be a vector for hepatotoxic shellfish poisoning in estuaries downstream of Microcystis blooms.
亚洲河蚬（Corbicula fluminea）和美洲牡蛎（Crassostrea virginica）分别是在受蓝藻水华（CHAB）影响的水道中及其下游发现的两种重要贝类资源。本研究考察了亚洲河蚬和美洲牡蛎作为来自水华微囊藻的肝毒素微囊藻毒素的载体的潜力。使用从伊利湖（菌株 LE-3）分离的产微囊藻毒素微囊藻培养物进行了实验室实验，以量化清除率、颗粒选择和肝毒素微囊藻毒素的积累，还进行了野外实验，使用了来自美国纽约州阿加旺湖的微囊藻水华的水。与铜绿微囊藻相比，微囊藻的清除率更快（p<0.05），而美洲牡蛎以相似的速率清除微囊藻和塔斯奇酵母。对于这两种贝类，水华水的清除率比培养物慢，而贝类在野外实验中对绿藻的选择性明显大于对野生蓝藻种群，而牡蛎则没有。在含有单细胞和双细胞的培养微囊藻实验中，两种贝类在 24-72 小时内积累了超过 3 µg 微囊藻毒素 g -1（湿重），远远超过加利福尼亚指导值（10 ng g -1），但在 4 天内喂食以大微囊藻菌落为主的水华水时，贝类仅积累了高达 2 ng 微囊藻毒素 g -1。对于亚洲河蚬，在暴露于有毒微囊藻 3-4 天后，清除率和组织微囊藻毒素含量下降。相比之下，在 3-4 天的暴露中，美洲牡蛎没有净化微囊藻毒素，并且积累的微囊藻毒素比贝类多一个数量级。这种对比表明，亚洲河蚬可能会通过在微囊藻水华期间降低清除率、选择性地以绿藻为食以及净化微囊藻毒素来积累少量的微囊藻毒素，而牡蛎则更有可能积累微囊藻毒素，因此更有可能成为微囊藻水华下游河口贝类中毒的载体。
