Marine Research Institute (INMAR)-Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, Puerto Real, Cádiz, Spain.
Marine Research Institute (INMAR)-Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, Puerto Real, Cádiz, Spain.
J Environ Manage. 2024 Sep;367:122021. doi: 10.1016/j.jenvman.2024.122021. Epub 2024 Jul 30.
Accumulations of macroalgal wrack are important for adequate functioning of the beach ecosystem. However, the sudden beaching of seaweed masses smothers the coastline and forms decomposing piles on the shore, harming tourism-based economies, but also affecting the beach ecosystem metabolism. The decomposition of sudden pulses of wrack can modify the biogeochemistry of beach sands and increase greenhouse gas (GHG) emissions. The presence of invasive species in the wrack deposits can superimpose harmful effects on the beach functioning. We quantified the wrack biomass of Rugulopteryx okamurae, an invasive species of extreme impact, on five sandy beaches from the Atlantic coast of the Strait of Gibraltar (Spain), and we tested the effects on in situ respiratory CO fluxes using an infrared gas analyser. All the beaches showed massive accumulations of Rugulopteryx wrack deposits. However, the biomass changed significantly between beaches, ranging (mean ± SE) from 968.3 ± 287.7 kg m to 9210 ± 1279.4 kg m of wet weight. Wrack supported high respiration rates, with CO fluxes averaging (±SE) 19.15 ± 5.5 μmol CO m s across beaches, reaching astounding maximum peaks of 291 μmol CO m s. The within-beach variability was related to the distance of the wrack deposits from the shoreline, as the average metabolic rates tended to increase significantly from the swash to the drift line. Thicker wrack and a more degraded algae stage showed significantly higher CO fluxes. We estimated that the annual CO flux of R. okamurae in our study area ranged between 0.39 (±0.01) and 23.30 (±11.33) kg C m y. We suggest that massive amounts of beach wrack can become a globally significant contributor to GHG emissions that can offset any potential carbon-sink capacity of macroalgal forests. However, the piles of wrack located several meters above the drift line showed non-measurable CO efflux. Transferring beach wrack from swash to drier upper-beach areas, a common practice in many coastal regions suffering from massive wrack accumulations, might help reduce GHG emissions while removing the wrack stockpiles from the intertidal. However, this practice is not necessarily suitable for all beaches and can create ecological and conservation problems in the dune system. There is an urgent need to implement practical and sustainable management practices for massive wrack deposits capable of presenting various solutions to achieve a balance between conservation and recreation actions, answering the consequences of a problem that links both, environmental and economic issues.
藤壶等大型藻类的堆积物对海滩生态系统的正常运转十分重要。然而，海藻大量突然涌上沙滩并在岸边堆积腐烂，这不仅会破坏旅游业为基础的经济，还会影响海滩生态系统的新陈代谢。藤壶等大型藻类的突然堆积分解会改变沙滩的生物地球化学性质，并增加温室气体（GHG）排放。藤壶等大型藻类的堆积物中如果存在入侵物种，还会对海滩的正常运转产生有害影响。我们在直布罗陀海峡（西班牙）大西洋沿岸的五个沙滩上量化了极度具有破坏性的入侵物种皱藤壶的藤壶堆积物的生物量，并使用红外气体分析仪测试了其对原位呼吸 CO 通量的影响。所有沙滩都有大量皱藤壶的藤壶堆积物。然而，沙滩之间的生物量差异显著，湿重范围（平均值±标准误差）为 968.3±287.7kg·m 至 9210±1279.4kg·m。藤壶堆积物支撑着较高的呼吸速率，CO 通量在整个沙滩上的平均值（±标准误差）为 19.15±5.5μmol CO m s，达到了惊人的 291μmol CO m s 的最高峰值。沙滩内的变异性与藤壶堆积物距海岸线的距离有关，因为随着从破浪带到漂流线的距离增加，平均代谢率有显著增加的趋势。较厚的藤壶堆积物和更退化的藻类阶段显示出更高的 CO 通量。我们估计，在我们的研究区域，皱藤壶每年的 CO 通量在 0.39（±0.01）至 23.30（±11.33）kg C m y 之间。我们认为，大量的海滩藤壶堆积物可能会成为温室气体排放的一个具有全球意义的重要贡献者，从而抵消大型藻类森林的任何潜在碳汇能力。然而，位于漂流线以上几米处的藤壶堆积物显示出无法测量的 CO 逸出。将藤壶堆积物从破浪带转移到较干燥的上游沙滩区域，这是许多遭受大量藤壶堆积物堆积的沿海地区的常见做法，这可能有助于减少温室气体排放，同时将藤壶堆积物从潮间带清除。然而，这种做法并不一定适用于所有沙滩，并且可能会在沙丘系统中产生生态和保护问题。迫切需要实施实用和可持续的管理实践，以处理大量的藤壶堆积物，为保护和娱乐活动提供各种解决方案，以应对将环境和经济问题联系在一起的问题的后果。
