Gálvez-Pastor Emma, Sánchez de Pedro Raquel, García-Sánchez María Jesús, Flores-Moya Antonio, Bañares-España Elena
Universidad de Málaga, Andalucía Tech, Departamento de Botánica y Fisiología Vegetal, Campus de Teatinos, 29010, Málaga, Spain.
Mar Environ Res. 2025 Jun;208:107105. doi: 10.1016/j.marenvres.2025.107105. Epub 2025 Mar 27.
The exotic invasive seaweed Rugulopteryx okamurae (Dictyotales, Ochrophyta) have posed a serious threat to coastal and marine habitats since its appearance in 2015 in the Strait of Gibraltar. This, together with multiple global change stressors, is leading to the disappearance of native foundational seaweeds. Here we explored the potential impacts that decomposing thalli of beach-cast R. okamurae (BCRo) might have on different life-stages of a native foundational seaweed (Ericaria selaginoides, Fucales, Ochrophyta). The in vitro effects of different biomass densities of BCRo and time exposure, in combination with three warming scenarios, were assessed across single- and few-celled stages and adult thalli of the native species. We hypothesized that R. okamurae might interfere in the survival and growth of E. selaginoides either by allelopathic interactions or water acidification, due to low intracellular pH of R. okamurae tissues. Sensitivity of E. selaginoides to the exposure of BCRo was stage- and thermal-dependent and decreased during early ontogenesis. Unfertilized oospheres (female gametes) exposed to BCRo experienced apoptotic-like cell death within less than 180 s, while embryo survival and germination dropped by 50 % and 36 %, respectively. Warming effects were not additive to that of BCRo, since higher growth reductions in 7-d old juveniles of E. selaginoides were detected at lower (20 °C) but not at higher temperatures (28 °C). Adults of E. selaginoides were the less sensitive stage but their growth was up to 7-times lower under BCRo addition. BCRo acidified natural sea water proportionally to the density and incubation time, reaching a pH of 7.2 after 24 h. However, that pH was not limiting for E. selaginoides juveniles and even enhanced their growth, suggesting an alternative chemical effect. This study highlighted the potential and overlooked deleterious effects that some species of beach-cast seaweeds can exert on the highly sensitive early developmental stages of native marine biota.
外来入侵海藻冈村凹顶藻（Rugulopteryx okamurae，网地藻目，褐藻门）自2015年出现在直布罗陀海峡以来，已对沿海和海洋栖息地构成严重威胁。这与多种全球变化压力因素一起，正导致本地基础海藻的消失。在此，我们探究了海滩上冲上岸的冈村凹顶藻（BCRo）的腐烂藻体可能对一种本地基础海藻（埃氏鹿角菜，鹿角菜目，褐藻门）的不同生活阶段产生的潜在影响。我们评估了不同生物量密度的BCRo和暴露时间，以及三种升温情景的体外效应，涵盖了本地物种的单细胞和少数细胞阶段以及成体藻体。我们假设，由于冈村凹顶藻组织的细胞内pH值较低，它可能通过化感相互作用或水酸化来干扰埃氏鹿角菜的存活和生长。埃氏鹿角菜对BCRo暴露的敏感性具有阶段和温度依赖性，并且在个体发育早期会降低。暴露于BCRo的未受精卵球（雌配子）在不到180秒内经历了类似凋亡的细胞死亡，而胚胎存活率和萌发率分别下降了50%和36%。升温效应与BCRo的效应并非相加关系，因为在较低温度（20℃）下，埃氏鹿角菜7日龄幼体的生长减少幅度更大，而在较高温度（28℃）下则未观察到这种情况。埃氏鹿角菜成体是最不敏感的阶段，但在添加BCRo的情况下，其生长速度降低了7倍。BCRo使天然海水按密度和孵育时间成比例酸化，24小时后pH值达到7.2。然而，该pH值对埃氏鹿角菜幼体并无限制，甚至还促进了它们的生长，这表明存在另一种化学效应。这项研究突出了一些海滩上冲上岸的海藻物种可能对本地海洋生物群高度敏感的早期发育阶段产生的潜在且被忽视的有害影响
