Alagna Adriana, Fernández Tomás Vega, Anna Giovanni D, Magliola Carlo, Mazzola Salvatore, Badalamenti Fabio
CNR-IAMC, Institute for Coastal Marine Environment, Castellammare del Golfo (TP), Italy.
Saipem S.p.A., San Donato Milanese (MI), Italy.
PLoS One. 2015 Apr 30;10(4):e0125321. doi: 10.1371/journal.pone.0125321. eCollection 2015.
In the last decades the growing awareness of the ecological importance of seagrass meadows has prompted increasing efforts to protect existing beds and restore degraded habitats. An in-depth knowledge of factors acting as major drivers of propagule settlement and recruitment is required in order to understand patterns of seagrass colonization and recovery and to inform appropriate management and conservation strategies. In this work Posidonia oceanica seedlings were reared for five months in a land-based culture facility under simulated natural hydrodynamic conditions to identify suitable substrates for seedling anchorage. Two main substrate features were investigated: firmness (i.e., sand vs. rock) and complexity (i.e., size of interstitial spaces between rocks). Seedlings were successfully grown in culture tanks, obtaining overall seedling survival of 93%. Anchorage was strongly influenced by substrate firmness and took place only on rocks, where it was as high as 89%. Anchorage occurred through adhesion by sticky root hairs. The minimum force required to dislodge plantlets attached to rocky substrates reached 23.830 N (equivalent to 2.43 kg), which would potentially allow many plantlets to overcome winter storms in the field. The ability of rocky substrates to retain seedlings increased with their complexity. The interstitial spaces between rocks provided appropriate microsites for seedling settlement, as seeds were successfully retained, and a suitable substrate for anchorage was available. In conclusion P. oceanica juveniles showed a clear-cut preference for hard substrates over the sandy one, due to the root system adhesive properties. In particular, firm and complex substrates allowed for propagule early and strong anchorage, enhancing persistence and establishment probabilities. Seedling substrate preference documented here leads to expect a more successful sexual recruitment on hard bottoms compared with soft ones. This feature could have influenced P. oceanica patterns of colonization in past and present time.
在过去几十年里，人们对海草草甸生态重要性的认识不断提高，这促使人们加大力度保护现有的海草床并恢复退化的栖息地。为了了解海草定殖和恢复的模式，并为适当的管理和保护策略提供依据，需要深入了解作为繁殖体沉降和补充主要驱动因素的各种因素。在这项研究中，将地中海海神草幼苗在陆基养殖设施中，在模拟自然水动力条件下饲养五个月，以确定适合幼苗固着的基质。研究了两个主要的基质特征：硬度（即沙子与岩石）和复杂性（即岩石间间隙空间的大小）。幼苗在养殖池中成功生长，总体幼苗存活率达到93%。固着受到基质硬度的强烈影响，并且只发生在岩石上，固着率高达89%。固着是通过粘性根毛的粘附实现的。将附着在岩石基质上的幼苗拔出所需的最小力达到23.830 N（相当于2.43 kg），这可能使许多幼苗能够在野外抵御冬季风暴。岩石基质保留幼苗的能力随着其复杂性的增加而提高。岩石间的间隙空间为幼苗沉降提供了合适的微生境，因为种子能够成功保留，并且有适合固着的基质。总之，由于根系的粘附特性，地中海海神草幼体对硬质基质的偏好明显高于沙质基质。特别是，坚硬且复杂的基质能够使繁殖体早期并牢固地固着，提高持久性和定植概率。此处记录的幼苗对基质的偏好表明，与软质海底相比，在硬质海底上有性繁殖的成功率更高。这一特征可能在过去和现在都影响了地中海海神草的定殖模式。
