Use of multi-beam sonar to map seagrass beds in Otsuchi Bay on the Sanriku Coast of Japan
Use of multi-beam sonar to map seagrass beds in Otsuchi Bay on the Sanriku Coast of Japan
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DOI：
10.1016/s0990-7440(03)00045-7
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发表时间：
2003-07
影响因子：
1.1
通讯作者：
T. Komatsu;C. Igarashi;K. Tatsukawa;S. Sultana;Yasuaki Matsuoka;Shuichi Harada
中科院分区：
文献类型：
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作者：
T. Komatsu;C. Igarashi;K. Tatsukawa;S. Sultana;Yasuaki Matsuoka;Shuichi Harada
海草床作为生境和环境结构的主要生产者和提供者，在沿海生态系统中发挥着重要作用。因此，绘制海草床的地图对于管理和养护健全的沿岸的生态系统以及在沿海沃茨发展可持续渔业是必不可少的。多波束声纳常用于绘制海底地形图。我们开发了一种映射方法，使用多波束声纳来量化海草的体积。利用多波束声纳对海草床进行扫描，并进行样方取样，以验证海草的分布。我们使用软件来区分海草信号和回波，以获得没有海草的海底地形剖面;然后从包括海草的地形中减去这一剖面。然后，我们绘制海草分布，计算海草体积，估计生物量使用体积和样方样本。我们应用这些方法来映射海草床大叶藻在大槌湾，日本三陆海岸，在2001年的生长季节。一个传感器被连接到一艘船上（一总吨），船上配备了差分GPS、运动传感器和陀螺罗盘。该船以1.5 m s-1（3节）的速度航行，在约40 min内完成了对整个海草床（面积为115 m × 156 m，底深为2 - 8 m）的网格调查。多波束声纳能够直观显示海草的三维分布情况，无需插值，并可利用水文学软件轻松估计海草所占的面积和体积。结果表明，Z. caulescens分布于6-7 m的底深，表面积为3 628 m2，体积为1 368 m3。海草地上和地下部分的平均生物量估计为28.6 gDW m-2（范围26.6 - 30.9）和15.9 gDW m-2（范围14.1 - 17.7）。我们的研究表明，多波束声纳是有效的映射和量化的海草床的空间分布，并可视化的海草冠层的景观。
Seagrass beds play an important role in coastal ecosystems as primary producers and providers of habitat and environmental structure. Therefore, mapping seagrass beds is indispensable in the management and conservation of sound littoral ecosystems, and in the development of sustainable fisheries in coastal waters. Multi-beam sonar is often used to map bottom topography. We developed a mapping method to quantify the volume of seagrass using a multi-beam sonar. Seagrass beds were scanned with the multi-beam sonar and quadrat sampled to verify the distribution of seagrasses. We used software to discriminate seagrass signals from echoes to obtain a topographic profile of the bottom without seagrass; this was then subtracted from the topography including the seagrass. We then mapped seagrass distribution, calculated seagrass volume, and estimated biomass using volume and quadrat samples. We applied these methods to map a seagrass bed of Zostera caulescens in Otsuchi Bay, on the Sanriku Coast of Japan, during the growing season of 2001. A transducer was attached to a boat (one gross ton) equipped with a differential-GPS, a motion sensor, and a gyrocompass. The vessel completed a grid survey scanning whole seagrass bed with an area of 115 m × 156 m at bottom depths between 2 and 8 m within about 40 min when traveling at a speed of 1.5 m s–1 (3 knots). The multi-beam sonar was able to visualize three-dimensional seagrass distribution without interpolation and easily to estimate area and volume occupied by the seagrass using hydrography software. The results indicated that Z. caulescens was distributed at bottom depths of 6–7 m with a surface area of 3 628 m2 and a volume of 1 368 m3. The mean biomass of above- and below-ground parts of seagrass were estimated to be 28.6 gDW m–2 (range 26.6–30.9) and 15.9 gDW m–2 (range 14.1–17.7). Our study demonstrated that multi-beam sonar is effective for mapping and quantifying the spatial distribution of seagrass beds, and for visualizing the landscape of the seagrass canopy.