Spatial partitioning of Zoantharian species (Suborder Brachycnemina) at intertidal rocky platforms of the Canary Islands
-
1
Department of Animal Biology, Edaphology and Geology, Faculty of Sciences, University of La Laguna, Spain
Zoantharians (Cnidaria: Anthozoa) are benthic cnidarians commonly found in marine habitats, from intertidal rocky platforms to the deep sea and in tropical and subtropical marine regions worldwide. Members of the genera Palythoa and Zoanthus (Brachycnemina) are particularly ubiquitous in rocky coastal zones, where some species are able to cover extensive areas. Recent studies have demonstrated that zoantharians are more resistant than hard corals to habitat degradation, pollution, oceanic acidification and the ongoing ocean warming. In fact, some species, such as Palythoa grandiflora, have been able to rapidly increase their populations causing phase-shifts in degraded coral reef ecosystems (Cruz et al., 2016). Their fast growth rates due to the lack of carbonate in their body walls, combined with an effective asexual reproduction and the production of powerful palytoxins, are probably involved in such colonization success. However, the effects of the actual increase in zoantharians populations at subtropical and temperate zones, where main structural elements of ecosystems are macroalgae, are still unknown.
Despite zoantharians are common sessile organisms, few studies have paid attention to this group in the subtropical region of the Canary Islands. Some of them have focused only in their toxins or taxonomy (Fraga et al., 2017; López et al., 2019) and ecological studies are still scarce. Understanding the causes of marine communities’ dynamics has gained the attention of many researchers interested in making species range predictions and their consequences for community structure. Given that zoantharians populations are predicted to increase northward in a climate change scenario (Durante et al., 2018), the aim of this study was to evaluate spatial partitioning among intertidal zoantharians populations, mainly considering their role in determining levels of macroalgae coverage which are main benthic ecosystem engineers in the Canary Islands.
Surveys were conducted in 30 intertidal rocky platforms around the Canary Islands (Spain). At each location three belt transects (20 x 4 m) were set parallel to the coastline, in order to count the number of colonies of the different zoantharian species found. Moreover, four quadrats (50 x 50 cm) randomly placed at each transect were photographed to in depth examine relationships between percentage of coverage of zoantharians, macroalgae and sessile invertebrates, as well any relation with free space (sandy or rocky substrate) by means of correlations analyses. Also, the number of tidepools was evaluated as potential habitats available for zoantharian species. Finally, substrate rugosity and inclination were evaluated by means of testing their effect over zoantharian populations by means of a distance-based permutational ANOVA.
Four Zoantharian Brachycnemina species were recorded along the transects throughout the Canary Islands: Palythoa aff. clavata, P. caribaeorum, Zoanthus pulchellus and Isaurus tuberculatus.
Zoantharian assemblages studied in terms of species composition and their number of colonies, were not influenced by the inclination of the rocky platform (F= 0.49, p= 0.654), and not significant relationship was detected between the number of colonies recorded and the number of the tidepools available (F= 2.52, p= 0.116). These results are probably due to the fact that P. aff. clavata was the dominant species throughout the Archipelago and it seems to tolerate desiccation better than the other species, with several colonies found outside tidepools. Species-specific analyses showed a significant effect of substrate rugosity over abundances of P. aff. clavata and Z. pulchellus (F= 4.54, p= 0.019; F= 6.99, p= 0.001, respectively), with increased numbers of colonies among the higher levels of rugosity. Previous studies have found a positive correlation between substrate complexity and the colonization of corals, that mainly favour larval settlement and development, which may explain the greater abundance of zoantharians colonies (Carleton & Sammarco, 1987). However, other factors such as shelter availability to cope with hydrodynamics or nutrient availability must be considered and may not be excluded as factors determining populations substrate partitioning.
The abundance of zoantharians was not related to the coverage of other sessile invertebrates (F= 1.41; p= 0.251), probably because of the small sizes of the species found. Most of the organisms recorded, such as Anemonia sulcata and Chthamalus stellatus, are not large enough to show a negative effect by the settlement of zoantharians species in the substrate, since colonies seem to leave enough free substrate for their growth. In fact, the density of zoantharians was positive correlated with the percentage of substrate available (Figure 1), with higher number of colonies found in places with greater free-space. However, when other sessile organisms with the ability to cover extensive substrate areas occur, such as macroalgae, spatial competition seems to greatly increase. Large coverage of erect macroalgae may also hinder small zoantharian colonies from growing due to a shading effect on these zooxanthellate species. In fact, the coverage of zoantharians showed a negative correlation with macroalgae cover, showing lower densities when algae dominated the substrate (Figure 2). Among the most common algae sharing the substrate with zoantharians we found Ellisolandia elongata, Jania rubens, Dictyota spp., Padina pavonica and Cystoseira spp., as well as undetermined turf algae. Spatial partitioning and processes of competition for space between macroalgae and hard corals have been extensively studied (Cruz et al., 2016), but studies that involve zoantharians species are still scarce. Our results indicate that zoantharian species may not take advantages of all substrate free-space and are greatly limited by intertidal macroalgae communities. However, altered ecosystems, either by the effect of climate change that may favour zoantharian growth or locations with high abundances of grazers that may leave wide unvegetated extensions available for zoantharians, may favour zoantharian populations extensions in the Canary Islands.
Figure 1. Significant relationship between substrate availability, measured as free rocky and sandy space (%), and abundance of zoantharians (number of colonies/ 80 m2).
Figure 2. Significant relationship between the space covered by zoantharians (%) and the space covered by erect macroalgae (%).
Acknowledgements
This study was conducted under the framework of the project MIMAR (MAC/4.6.d/066 - INTERREG MAC 2014-2020). We thank Alberto Brito and Cristina Villanova for their help in field research. C. López was co-funded by the Canarian Agency for Research, Innovation and Information Society of the Ministry of Economy, Industry, Trade and Knowledge and by the European Social Fund (ESF) integrated operational program of the Canary Islands 2014–2020.
References
Carleton, J.H. & Sammarco, P.W. 1987 Effects of substratum irregularity on success of coral settlement: quantification by comparative geomorphological techniques. Bull. Mar. Sci., 40(1):85-98.
Cruz, I.; Henschen, V.; Kenji, R. & Creed, J.C. 2016 The role of competition in the phase shift to dominance of the zoanthid Palythoa cf. variabilis on coral reefs. Mar. Environ. Res., 115:28-35.
Durante, L.M.; Cruz, I. & Lofuto, T. 2018 The effect of climate change on the distribution of a tropical zoanthid (Palythoa caribaeorum) and its ecological implications. J. Mar. Biol. Assoc. UK, 95(2):301-309.
Fraga, M.; Vilariño, N.; Louzano, M.C.; Molina, L.; López, Y.; Poli, M. & Botana, L.M. 2017 First Identification of Palythoxin like molecules in the Atlantic Coral Species Palythoa canariensis. Anal. Chem., 89(14):7438-7446.
López, C.; Reimer, J.D.; Brito, A.; Simón, D.; Clemente, S. & Hernández, M. 2019 Diversity of zoantharian species and their symbionts from the Macaronesian and Cape Verde ecoregions demonstrates their widespread distribution in the Atlantic Ocean. Coral Reefs, 38(2):269-283.
Keywords:
Climate Change,
intertidal,
Rocky platforms,
Zoantharians,
Canary Islands
Conference:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019.
Presentation Type:
Poster Presentation
Topic:
Ecology, Biodiversity and Vulnerable Ecosystems
Citation:
Fernández Martín
S,
López Batista
C,
Rodríguez Hernández
A,
Moreno Borges
S and
Clemente Martín
S
(2019). Spatial partitioning of Zoantharian species (Suborder Brachycnemina) at intertidal rocky platforms of the Canary Islands.
Front. Mar. Sci.
Conference Abstract:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) .
doi: 10.3389/conf.fmars.2019.08.00114
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
28 Aug 2019;
Published Online:
27 Sep 2019.
*
Correspondence:
Miss. Sonia Fernández Martín, Department of Animal Biology, Edaphology and Geology, Faculty of Sciences, University of La Laguna, San Cristobal de La Laguna, Spain, soniafernandezmartin22@gmail.com