López Boris A, Macaya Erasmo C, Tala Fadia, Tellier Florence, Thiel Martin
Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile.
Departamento de Acuicultura y Recursos Agroalimentarios, Universidad de Los Lagos, Avenida Fuchslocher 1305, Osorno, Chile.
J Phycol. 2017 Feb;53(1):70-84. doi: 10.1111/jpy.12479. Epub 2016 Nov 28.
Dispersal on floating seaweeds depends on availability, viability, and trajectories of the rafts. In the southern hemisphere, the bull kelp Durvillaea antarctica is one of the most common floating seaweeds, but phylogeographic studies had shown low connectivity between populations from continental Chile, which could be due to limitations in local supply and dispersal of floating kelps. To test this hypothesis, the spatiotemporal dynamics of kelp strandings were examined in four biogeographic districts along the Chilean coast (28°-42°S). We determined the biomass and demography of stranded individuals on 33 beaches for three subsequent years (2013, 2014, 2015) to examine whether rafting is restricted to certain districts and seasons (winter or summer). Stranded kelps were found on all beaches. Most kelps had only one stipe (one individual), although we also frequently found coalesced holdfasts with mature males and females, which would facilitate successful rafting dispersal, gamete release, and reproduction upon arrival. High biomasses of stranded kelps occurred in the northern-central (30°S-33°S) and southernmost districts (37°S-42°S), and lower biomasses in the northernmost (28°S-30°S) and southern-central districts (33°S-37°S). The highest percentages and sizes of epibionts (Lepas spp.), indicative of prolonged floating periods, were found on stranded kelps in the northernmost and southernmost districts. Based on these results, we conclude that rafting dispersal can vary regionally, being more common in the northernmost and southernmost districts, depending on intrinsic (seaweed biology) and extrinsic factors (shore morphology and oceanography) that affect local supply of kelps and regional hydrodynamics.
借助漂浮的海藻进行扩散取决于筏子的可用性、活力和漂流轨迹。在南半球，南极巨藻是最常见的漂浮海藻之一，但系统地理学研究表明，智利大陆不同种群之间的连通性较低，这可能是由于当地漂浮海带的供应和扩散存在限制。为了验证这一假设，我们沿着智利海岸（南纬28°-42°）的四个生物地理区域研究了海带搁浅的时空动态。我们在随后三年（2013年、2014年、2015年）对33个海滩上搁浅个体的生物量和种群统计学特征进行了测定，以检验漂流是否局限于特定区域和季节（冬季或夏季）。在所有海滩均发现了搁浅的海带。大多数海带只有一个叶柄（单株个体），不过我们也经常发现带有成熟雄藻和雌藻的愈合固着器，这将有助于漂流扩散、配子释放以及到达后的繁殖。搁浅海带生物量较高的区域位于中北部（南纬30°-33°）和最南端区域（南纬37°-42°），而最北部（南纬28°-30°）和中南部区域（南纬33°-37°）的生物量较低。在最北部和最南端区域搁浅的海带表面，发现了最高比例和最大尺寸的附着生物（茗荷属），这表明海带的漂浮时间较长。基于这些结果，我们得出结论，漂流扩散在不同区域存在差异，在最北部和最南端区域更为常见，这取决于影响海带当地供应和区域流体动力学的内在因素（海藻生物学特性）和外在因素（海岸形态和海洋学特征）。
