ABSTRACT Cystoseira abies-marina is a canopy-forming brown seaweed distributed along the western Mediterranean and the adjacent Atlantic coasts, which has suffered massive declines in recent decades, particularly in the Canary Islands. Here, we describe seasonal variation in the canopy structure of this alga, addressing the role of environmental drivers. Four sites around the island of Gran Canaria were investigated monthly during an entire annual cycle. Annually, the non-fertile stage made up the majority of populations, in terms of frond density, while the fertile stage was comparatively sparser. This fertile stage, however, had the largest biomass and reached the longest lengths, showing significant seasonality. Best fitted GAM models included wave action, PAR and seawater temperature, but only accounted for a moderate variation in the seasonal frond structure of this alga. Total frond biomass, mostly fertile fronds, showed a bimodal pattern, with a peak in spring and a less accentuated peak in late summer–early autumn. This pattern was particularly obvious at sites with a wide annual variation in wave action, with lower biomass at times of high wave action. The frond size-structure was dominated, at all sites and times, by small fronds. The high frond density seems to promote intraspecific facilitation throughout the year. These results provide fundamental knowledge to improve the conservation and potential restoration actions for endangered populations of this alga.

中文翻译：

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大加那利岛（加那利群岛，大西洋东部）濒临灭绝的棕色巨藻 Cystoseira abies-marina 树冠结构的季节性

摘要 Cystoseira abies-marina 是一种形成树冠的棕色海藻，分布在地中海西部和邻近的大西洋沿岸，近几十年来，尤其是在加那利群岛，其数量大幅减少。在这里，我们描述了这种藻类冠层结构的季节性变化，解决了环境驱动因素的作用。在整个年度周期中，每月对大加那利岛周围的四个地点进行调查。每年，就叶片密度而言，非可育期占种群的大多数，而可育期则相对较少。然而，这个肥沃的阶段具有最大的生物量和最长的长度，显示出显着的季节性。最适合的 GAM 模型包括波浪作用、PAR 和海水温度，但只解释了这种藻类季节性叶结构的适度变化。总叶生物量，主要是可育叶，显示出双峰模式，在春季达到峰值，在夏末至初秋出现不那么突出的峰值。这种模式在波浪作用年度变化较大的地点尤其明显，在高波浪作用时生物量较低。在所有地点和时间，叶的大小结构都由小叶支配。高叶密度似乎全年促进种内促进。这些结果为改善这种藻类濒危种群的保护和潜在恢复行动提供了基础知识。春季出现高峰，夏末至初秋出现较不明显的高峰。这种模式在波浪作用年度变化较大的地点尤其明显，在高波浪作用时生物量较低。在所有地点和时间，叶状体的大小结构都以小叶状体为主。高叶密度似乎促进了全年的种内促进作用。这些结果为改善这种藻类濒危种群的保护和潜在恢复行动提供了基础知识。春季出现高峰，夏末至初秋出现较不明显的高峰。这种模式在波浪作用年度变化较大的地点尤其明显，在高波浪作用时生物量较低。在所有地点和时间，叶状体的大小结构都以小叶状体为主。高叶密度似乎全年促进种内促进。这些结果为改善这种藻类濒危种群的保护和潜在恢复行动提供了基础知识。