The Punta de la Mona Rhodolith Bed: Shallow-Water Mediterranean Rhodoliths (Almuñecar, Granada, Southern Spain) Del Río, Jesús Ramos Estenzo, Dino Angelo Sánchez Tocino, Luis Peñas De Giles, Julio Braga Alarcón, Juan Carlos Coralline red algae Depth-gradient patterns Rhodolith cover and size Rhodolith diversity Alboran Sea ACKNOWLEDGMENTS DAR work was funded by EU Horizon 2020 research and innovation program Marie Sklodowska-Curie Grant Agreement No. 813360. We would like to thank Isabel Sánchez for facilitating the SEMimaging remotely. We are grateful to two reviewers whose comments helped to improve the article. FUNDING This work was partly funded by the Junta de Andalucía Research Group RNM 190. SUPPLEMENTARY MATERIAL The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/feart.2022.884685/ full#supplementary-material Shallow-water rhodolith beds are rare in the Mediterranean Sea and generally poorly known. The Punta de la Mona rhodolith bed extends for 16,000 square meters in shallow and oligotrophic waters at the southern coast of Spain, off Almuñecar in the Alborán Sea. We present a detailed analysis of the structure (rhodolith cover and density, rhodolith size and shape, sediment granulometry) and morphospecies composition of the bed along a depth gradient. A stratified sampling was carried out at six depths (9, 12, 15, 18, 21, and 24 m), estimating rhodolith cover and abundance; rhodoliths were collected from one 30 by 30 cm quadrat for each transect, resulting in 18 samples and a total of 656 rhodoliths. The collected rhodoliths were measured and the coralline algal components identified morphoanatomically through a stereomicroscope and SEM. Sediment on the seafloor mainly consisted of pebbles and cobbles; the highest rhodolith cover occurred between 15 and 18 m, and the lowest at the shallowest and deepest transects (9 and 24 m). Mean Rhodolith size was similar throughout the depth range (23–35 mm) with a slight increase at 24 m, although the largest rhodoliths occurred at 21 m. In monospecific rhodoliths, size depended more on the forming species than on depth. We found 25 non-geniculate coralline morphospecies, nearly all rhodolith-forming morphospecies reported in the Mediterranean Sea in recent accounts. The highest morphospecies richness (18–19) and proportional abundance were found at intermediate depths (15–18 m), where rhodolith cover is also highest. Lithophyllum incrustans and Lithophyllum dentatum dominated at shallow depths (9–12 m), whereas Lithothamnion valens was the dominant species at intermediate and greater depths. Overall, the latter species was the most common in the rhodolith bed. The shallow-water rhodolith bed in Punta de la Mona is probably the most diverse in the Mediterranean Sea. This highlights the importance of the conservation of this habitat and, in general, emphasizes the role of the Alborán Sea as a diversity center of coralline algae. The Punta de la Mona example contradicts the common assumption in the geological literature that rhodolith beds are indicative of oligophotic environments with high nutrients levels. 2022-07-26T07:40:37Z 2022-07-26T07:40:37Z 2022-06-22 info:eu-repo/semantics/article Del Río J, Ramos DA, Sánchez-Tocino L, Peñas J and Braga JC (2022) The Punta de la Mona Rhodolith Bed: Shallow-Water Mediterranean Rhodoliths (Almuñecar, Granada, Southern Spain). Front. Earth Sci. 10:884685. [doi: 10.3389/feart.2022.884685] http://hdl.handle.net/10481/76345 10.3389/feart.2022.884685 eng info:eu-repo/grantAgreement/EC/H2020/Marie Sklodowska-Curie Grant Agreement No. 813360 http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess Atribución 4.0 Internacional Frontiers Media