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⁻¹) maintained at normoxic levels (7.2 mg L⁻¹ ± S.D. 0.47 dissolved oxygen), 2) moderate hypoxia (1.6 mg L⁻¹ ± S.D. 0.42 dissolved oxygen) with no K. brevis, 3) moderate hypoxia (1.5 mg L⁻¹ ± S.D. 0.43 dissolved oxygen) with a high concentration of K. brevis, 4) severe hypoxia with no K. brevis (0.69 mg L⁻¹ ± S.D. 0.36 dissolved oxygen), 5) severe hypoxia (0.63 mg L⁻¹ ± S.D. 0.40 dissolved oxygen) with a high concentration of K. brevis, and 6) a normoxic control (7.3 mg L⁻¹ ± 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.

佛罗里达赤潮是由鞭毛小鞭毛藻（Karenia brevis）引起的有害藻类繁殖，几乎每年都会在佛罗里达的海湾沿岸发生。近年来，佛罗里达州的赤潮水华变得更加普遍，频繁和强烈。从海牛到科利尔县的佛罗里达州西南海岸自2011年以来经历了多次重复和延长的K. brevis开花，2017年的最近一次开花持续了17个月，导致缺氧和缺氧事件。因此，我们确定了合法的短吻蟹对短毛K. K的存活率和嗜睡程度（例如，缺乏反应能力或行为反应减少）。和缺氧同时作为单一和同时的应激源。螃蟹被随机分配到六种处理方法之一，其中包括：1）高浓度的有毒短螺旋体（> 1百万个细胞L ^-1）保持在常氧水平（7.2 mg L ^-1 ±SD 0.47溶解氧），2）中度缺氧（1.6 mg L ^-1 ±SD 0.42溶解氧），无短毛K.，3）中度缺氧（1.5 mg L ^-1 ±SD 0.43溶解氧），高浓度的K. brevis，4）严重缺氧，无短杆菌K.（0.69 mg L ^-1 ±SD 0.36溶解氧），5）严重缺氧（0.63 mg L ^-1±SD 0.40的溶解氧）和高浓度的K. brevis； 6）常氧对照（7.3 mg L ^-1 ±SD 0.61的溶解氧），不含K. brevis。每10-12小时监测生存和石蟹嗜睡或反应能力，持续6天。螃蟹同时暴露于K. brevis与严重缺氧相比，存活率降低了43％，并且在24小时内嗜睡增加（相对于对照组，存活率降低了7％，嗜睡率没有增加）。普遍缺乏响应能力或活动能力，证明了低氧暴露过程中压力水平的提高和行为不振，这表明石蟹的近岸种群不太可能从这种条件下移出，这表明长期的K. brevis可能会减少未来的收成绽放和缺氧事件。