Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki City, Nagasaki, Japan.
Faculty of Fisheries, Nagasaki University, Nagasaki City, Nagasaki, Japan.
PeerJ. 2023 Jun 13;11:e15511. doi: 10.7717/peerj.15511. eCollection 2023.
In temperate macroalgal forests, sea urchins are considered as a keystone species due to their grazing ability. Given their potential to shape benthic communities, we monitored the habitat use by three sympatric sea urchin species and compared their behaviors in a vegetated habitat (VH) and an adjacent isoyake habitat (IH).
We monitored the environmental conditions and sea urchin density along deep and shallow transects of the VH and IH for over a year. The benthic rugosity at both sites were also surveyed. A mark-recapture experiment was conducted on the two most abundant sea urchins, and , to elucidate sea urchin movement patterns and group dynamics.
We found that exposure to waves was highest at the VH while the IH was sheltered. The deep IH experienced the least amount of light due to high turbidity. Water temperature patterns were similar across sites. The VH benthic topography was more rugose compared to the smoother and silt-covered IH substate. Peak macroalgal bloom occurred three months earlier in IH, but macroalgae persisted longer at the shallow VH. Among the sympatric sea urchins, was most abundant at the shallow VH and was observed in pits and crevices. The most abundant across IH and in the deep VH was , preferring either crevices or free-living, depending on hydrodynamic conditions. The least abundant species was , and most often observed in crevices. Small and medium sea urchins were most often observed at the IH site, whereas larger sea urchins were more likely observed at the VH. The mark-recapture study showed that was found to displace further at the IH, and was more sedentary. Additionally, was always observed in groups, whereas was always solitary.
The behaviors of sympatric urchins, and , differed in response to changes in the benthic environment and physical conditions. Sea urchin displacement increased when rugosity and wave action were low. Habitat preference shifted to crevices in seasons with high wave action. In general, the mark-recapture experiment showed that sea urchins displaced further at night.
在温带大型海藻林中，海胆被认为是关键物种，因为它们具有食草能力。鉴于它们塑造底栖群落的潜力，我们监测了三种共生海胆物种的栖息地利用情况，并比较了它们在植被栖息地 (VH) 和相邻的石狩栖息地 (IH) 中的行为。
我们在 VH 和 IH 的深和浅横断面上监测了一年多的环境条件和海胆密度。还调查了两个地点的底质粗糙度。对两种最丰富的海胆 和 进行了标记重捕实验，以阐明海胆的运动模式和群体动态。
我们发现 VH 处的波暴露最高，而 IH 处则受到庇护。由于高浊度，深 IH 处的光最少。水温模式在各站点相似。与更光滑和覆盖有淤泥的 IH 亚区相比，VH 的底质地形更加粗糙。在 IH 中，最大的海藻爆发发生在三个月前，但在浅 VH 中，海藻持续时间更长。在共生的海胆中， 在浅 VH 中最为丰富，在坑洼和裂缝中被观察到。最丰富的是 ，在 IH 和深 VH 中，它更喜欢裂缝或自由生活，这取决于水动力条件。最不丰富的物种是 ，最常见于裂缝中。小和中型海胆最常在 IH 站点观察到，而较大的海胆更可能在 VH 上观察到。标记重捕研究表明， 在 IH 处被发现的位移更大，而 则更久坐不动。此外， 总是成群结队出现，而 总是单独出现。
共生海胆 、 和 的行为因底栖环境和物理条件的变化而不同。当粗糙度和波浪作用较低时，海胆的位移增加。在波浪作用大的季节，栖息地偏好转向裂缝。一般来说，标记重捕实验表明，海胆在夜间移动得更远。
