Hinz Hilmar, Reñones Olga, Gouraguine Adam, Johnson Andrew F, Moranta Joan
Instituto Mediterraneo de Estudios Avanzados (IMEDEA; CSIC-UIB), Esporles, Illes Balears, Spain.
Instituto Español de Oceanografía (IEO), Centre Oceanográfic de les Balears, Ecosystem Oceanography Group (GRECO), Palma, Illes Balears, Spain.
PeerJ. 2019 May 15;7:e6797. doi: 10.7717/peerj.6797. eCollection 2019.
The nursery function of coastal habitats is one of the most frequently mentioned and recognized ecosystem services in the valuation of coastal ecosystems. Despite its importance our understanding of the precise habitat parameters and mechanisms that make a habitat important as a nursery area is still limited for many species. The study aimed to establish the importance of different algae morphotypes in providing shelter and food for juvenile coastal fish during the main settlement peaks, in early spring and late summer, in littoral rocky reef systems in the Northwestern Mediterranean. The results of our study showed strong seasonal differences in algae cover, composition and height between the two sampling periods. Overall, during spring the algae were well developed, while in late summer, both density and height, of most algae decreased considerably. Equally, prey biomass, in form of suitable sized invertebrate fauna associated to the algae, decreased. Accordingly, the shelter and food for the fish settling in this habitat during late summer were less abundant, indicating a mismatch between the observed presence of juvenile fish and optimal habitat conditions. Differences in prey densities were detected between algae morphotypes, with structurally more complex algae, such as spp. and spp. consistently containing more prey, independent of season, compared to simpler structured morphotypes such as Dictoytales. The study furthermore related juvenile fish density to habitats dominated by different algae morphotypes. Out of the three-study species () only showed a significant association with an algae habitat. related positively to habitats dominated by Dictoytales which provided the highest cover during late summer but had the lowest prey densities. A strong association of this species with , as reported by other studies, could not be confirmed. was abundant within the study area but in a state of dieback, showing loss and reduced height of foliage, typical for the time of year within the study area. It is therefore likely that algae-fish associations are context-dependent and that several algae species may fulfil similar functions. We also discovered that prey biomass did not appear to have an important effect on juvenile abundances. Nevertheless, the availability of prey may influence juvenile fish condition, growth performance and ultimately long-term survival. We therefore suggest that future studies on habitat quality should also include, besides abundance, indicators related to the condition and growth of juveniles.
沿海栖息地的育苗功能是沿海生态系统估值中最常被提及和认可的生态系统服务之一。尽管其很重要，但对于许多物种而言，我们对使一个栖息地成为重要育苗区的确切栖息地参数和机制的理解仍然有限。该研究旨在确定不同藻类形态类型在早春和夏末这两个主要定居高峰期，为地中海西北部沿海岩石礁系统中的幼鱼提供庇护所和食物方面的重要性。我们的研究结果表明，两个采样期之间藻类覆盖度、组成和高度存在强烈的季节差异。总体而言，春季藻类生长良好，而夏末大多数藻类的密度和高度都大幅下降。同样，与藻类相关的合适大小的无脊椎动物群形式的猎物生物量也减少了。因此，夏末在该栖息地定居的鱼类的庇护所和食物变得不那么丰富，这表明观察到的幼鱼存在与最佳栖息地条件之间存在不匹配。在藻类形态类型之间检测到猎物密度的差异，与结构较简单的形态类型（如羽藻目）相比，结构更复杂的藻类（如某些物种）始终含有更多猎物，且不受季节影响。该研究还将幼鱼密度与以不同藻类形态类型为主的栖息地联系起来。在三种研究物种中，只有一种与藻类栖息地有显著关联。某物种与羽藻目为主的栖息地呈正相关，羽藻目在夏末提供了最高的覆盖率，但猎物密度最低。其他研究报告的该物种与另一种藻类的强关联无法得到证实。某物种在研究区域内数量丰富，但处于衰退状态，表现出叶片损失和高度降低，这是研究区域内一年中这个时候的典型特征。因此，藻类与鱼类的关联可能取决于具体情况，并且几种藻类物种可能发挥类似的功能。我们还发现猎物生物量似乎对幼鱼数量没有重要影响。然而，猎物的可获得性可能会影响幼鱼的状况、生长性能以及最终的长期生存。因此，我们建议未来关于栖息地质量的研究除了数量之外，还应包括与幼鱼状况和生长相关的指标。
