Tol S J, Carter A B, York P H, Jarvis J C, Grech A, Congdon B C, Coles R G
Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), James Cook University, Cairns, Australia; College of Science and Engineering, James Cook University, Cairns, Australia.
Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), James Cook University, Cairns, Australia.
Mar Environ Res. 2023 Oct;191:106160. doi: 10.1016/j.marenvres.2023.106160. Epub 2023 Sep 4.
Long distance dispersal (LDD) contributes to the replenishment and recovery of tropical seagrass habitats exposed to disturbance, such as cyclones and infrastructure development. However, our current knowledge regarding the physical attributes of seagrass fragments that influence LDD predominantly stems from temperate species and regions. The goal of this paper is to measure seagrass fragment density and viability in two tropical species, assessing various factors influencing their distribution.
We measured the density and viability of floating seagrass fragments for two tropical seagrass species (Zostera muelleri and Halodule uninervis) in two coastal seagrass meadows in the central Great Barrier Reef World Heritage Area, Australia. We assessed the effect of wind speed, wind direction, seagrass growing/senescent season, seagrass meadow density, meadow location and dugong foraging intensity on fragment density. We also measured seagrass fragment structure and fragment viability; i.e., potential to establish into a new plant.
We found that seagrass meadow density, season, wind direction and wind speed influenced total fragment density, while season and wind speed influenced the density of viable fragments. Dugong foraging intensity did not influence fragment density. Our results indicate that wave action from winds combined with high seagrass meadow density increases seagrass fragment creation, and that more fragments are produced during the growing than the senescent season. Seagrass fragments classified as viable for Z. muelleri and H. uninervis had significantly more shoots and leaves than non-viable fragments. We collected 0.63 (±0.08 SE) floating viable fragments 100 m in the growing season, and 0.13 (±0.03 SE) viable fragments 100 m in the senescent season. Over a third (38%) of all fragments collected were viable.
There is likely to be a large number of viable seagrass fragments available for long distance dispersal. This study's outputs can inform dispersal and connectivity models that are used to direct seagrass ecosystem management and conservation strategies.
长距离扩散（LDD）有助于遭受干扰（如气旋和基础设施建设）的热带海草栖息地的补充和恢复。然而，我们目前关于影响长距离扩散的海草碎片物理属性的知识主要源于温带物种和地区。本文的目的是测量两种热带物种中海草碎片的密度和活力，评估影响其分布的各种因素。
我们在澳大利亚大堡礁世界遗产中心区域的两个沿海海草草甸中，测量了两种热带海草物种（穆氏泰来草和无脉二药藻）漂浮海草碎片的密度和活力。我们评估了风速、风向、海草生长/衰老季节、海草草甸密度、草甸位置和儒艮觅食强度对碎片密度的影响。我们还测量了海草碎片结构和碎片活力，即形成新植株的潜力。
我们发现海草草甸密度、季节、风向和风速影响总碎片密度，而季节和风速影响有活力碎片的密度。儒艮觅食强度不影响碎片密度。我们的结果表明，风引起的波浪作用与高海草草甸密度共同增加了海草碎片的产生，并且生长季节产生的碎片比衰老季节更多。被归类为穆氏泰来草和无脉二药藻有活力的海草碎片比无活力的碎片有更多明显的茎和叶。我们在生长季节每100米收集到0.63（±0.08标准误）个漂浮有活力碎片，在衰老季节每100米收集到0.13（±0.03标准误）个有活力碎片。所有收集到的碎片中超过三分之一（38%）是有活力的。
可能有大量有活力的海草碎片可用于长距离扩散。本研究的结果可为用于指导海草生态系统管理和保护策略的扩散和连通性模型提供信息。
