Mote Marine Laboratory, Fisheries Ecology and Enhancement Program, 1600 Ken Thompson Parkway, Sarasota, FL 34236, United States; Florida Southern College, Department of Biological Sciences, 111 Lake Hollingsworth Drive, Lakeland, FL 33801, United States.
Department of Biological Sciences, University of New Hampshire, 38 Academic Way Durham, NH 03824, United States.
Harmful Algae. 2020 Sep;98:101897. doi: 10.1016/j.hal.2020.101897. Epub 2020 Sep 2.
Florida red tides are harmful algae blooms caused by the dinoflagellate Karenia brevis, which occur along Florida's gulf coast almost annually. In recent years Florida red tide blooms have become more common, frequent, and intense. Florida's southwest coast, from Manatee to Collier County, has experienced repeated and prolonged K. brevis blooms since 2011 with the most recent bloom in 2017 lasting 17 months and resulting in both hypoxic and anoxic events. We therefore determined the survival and level of lethargy (e.g., lack of responsiveness or reduction in behavioral reactions) of sublegal stone crabs to K. brevis and hypoxia as both singular and simultaneous stressors. Crabs were randomly assigned to one of six treatments that included: 1) high concentration of toxic K. brevis (> 1 million cells L) maintained at normoxic levels (7.2 mg L ± S.D. 0.47 dissolved oxygen), 2) moderate hypoxia (1.6 mg L ± S.D. 0.42 dissolved oxygen) with no K. brevis, 3) moderate hypoxia (1.5 mg L ± S.D. 0.43 dissolved oxygen) with a high concentration of K. brevis, 4) severe hypoxia with no K. brevis (0.69 mg L ± S.D. 0.36 dissolved oxygen), 5) severe hypoxia (0.63 mg L ± S.D. 0.40 dissolved oxygen) with a high concentration of K. brevis, and 6) a normoxic control (7.3 mg L ± S.D. 0.61 dissolved oxygen) with no K. brevis. Survival and stone crab lethargy or responsiveness was monitored every 10-12 h for six days. Crabs simultaneously exposed to K. brevis and severe hypoxia exhibited a 43% decrease in survival and experienced increased lethargy within 24 h relative to the control (7% decrease in survival, no increase in lethargy). The increase in stress level and sluggish behavior during exposure to hypoxia was evident by a general lack of responsiveness or movement which indicates that nearshore populations of stone crabs are unlikely to emigrate away from such conditions suggesting that future harvests may be reduced following prolonged K. brevis blooms and hypoxic events.
佛罗里达红潮是由夜光藻属的哈氏菱形藻引起的有害藻类大量繁殖，这种藻类几乎每年都会在佛罗里达的墨西哥湾沿岸出现。近年来，佛罗里达红潮的爆发变得更加频繁和强烈。自 2011 年以来，佛罗里达州西南部的曼尼提斯到科利尔县的海岸经历了反复和长时间的哈氏菱形藻爆发，最近一次爆发持续了 17 个月，导致缺氧和无氧事件。因此，我们确定了亚法螃蟹对哈氏菱形藻和低氧的生存能力和昏睡程度（例如，缺乏反应或减少行为反应），作为单一和同时的应激源。螃蟹被随机分配到六个处理组中的一个，包括：1）高浓度的有毒哈氏菱形藻（> 100 万个细胞 L）保持在正常氧水平（7.2 mg L ± S.D. 0.47 溶解氧），2）中度缺氧（1.6 mg L ± S.D. 0.42 溶解氧）没有哈氏菱形藻，3）中度缺氧（1.5 mg L ± S.D. 0.43 溶解氧）有高浓度的哈氏菱形藻，4）没有哈氏菱形藻的严重缺氧（0.69 mg L ± S.D. 0.36 溶解氧），5）严重缺氧（0.63 mg L ± S.D. 0.40 溶解氧）有高浓度的哈氏菱形藻，6）正常氧对照（7.3 mg L ± S.D. 0.61 溶解氧）没有哈氏菱形藻。在六天的时间里，每 10-12 小时监测一次螃蟹的生存和昏睡或反应能力。同时暴露在哈氏菱形藻和严重缺氧下的螃蟹的存活率下降了 43%，与对照组相比（存活率下降 7%，昏睡程度没有增加），昏睡程度增加。在缺氧暴露期间，应激水平和缓慢的行为变化明显，表现为普遍缺乏反应或运动，这表明近岸石蟹种群不太可能离开这种条件，这表明在哈氏菱形藻大量繁殖和缺氧事件后，未来的捕捞量可能会减少。
