Wittrockiella salina Wille

Salazar-Forero, Camila Esperanza, Gavio, Brigitte & Wynne, Michael J., 2021, Macroalgae associated with aerial roots of Rhizophora mangle in Islas del Rosario, Colombia, Southwestern Caribbean, Caldasia 43 (1), pp. 94-104 : 100-101

Wittrockiella salina Wille ** x

the general aspect of the thallus (compact vs. fluffy in D. caraibica ) and the falciform and thick branchlets ( Rodriguez-Prieto et al. 2013), which in Dasya caraibica are long and delicate ( Fig. 3a ).

Melanothamnus pseudovillum , originally described as Polysiphonia pseudovillum by Hollenberg (1968) is a creeping species with closed-connected rhizoids, four pericentral cells, ecorticated, and branches replacing trichoblasts. In the Western Atlantic it has been reported for North Carolina ( Schneider and Searles 1991), Florida ( Littler and Littler 2000), Mexico ( García-García et al. 2020) and Panama ( Mamoozadeh and Freshwater 2011). Recently, Díaz-Tapia et al. (2017) reinstated the genus Melanothamnus , where this species was accommodated.

Parviphycus setaceus is a species originally described for the Antilles (Guiry and Guiry c2020) and widely distributed in the Caribbean Sea (as Gelidiella setacea (Feldmann) Feldmann and Hamel, Littler and Littler 2000 ). It is typi- cally observed on mangrove prop roots ( Littler and Littler 2000, Littler et al. 2008), where it grows inconspicuously.

Wittrockiella salina Chapman is a species originally described for New Zealand and distributed along Australia, Tasmania, and Japan, in the Pacific Ocean. In 1984 van den Hoek et al. (1984) reported the species as epiphytic on aerial roots of Rhizophora mangle and on pneumatophores of Avicennia nitida Jacq. on the island of Curacao, Netherland Antilles, in the Southern Caribbean Sea. The alga is small, inconspicuous, grows as an epiphyte on larger algae, so it may go easily undetected. It is difficult to determine if this species has been introduced in the Caribbean Sea, and expanding, or if mangrove aerial roots in the southern Caribbean basin have always been its natural environment.

Although the overall diversity of the biocenosis associated with mangrove prop roots is high (e.g. Riosmena-Rodriguez et al. 2011), single studies seldom report a high number of species. Some authors have regarded mangrove habitats as having a low diversity of epiphytes ( Huisman et al. 2015); King (1981) suggested that these habitats are unfavorable due to a lack of stable substratum (excluding the mangroves), mud in suspension, and the physiological stress due to fluctuating salinity. Riosmena-Rodriguez et al. (2011) associated a high diversity of algae on mangrove roots to the presence of other habitats close-by, such as seagrass or rhodoliths beds and hard substrate such as rocky shores. When these habitats are not present, the algal diversity is much lower. In Cholón, the mangroves were adjacent to seagrass beds, and coral reef patches were observed in the area. Furthermore, artificial hard substrate is present close by in the form of spurs.

Considering that we analyzed only three roots, the diversity of this phytocenosis in the Park is grossly underestimated. Most species are microscopic, filamentous, and easily overlooked. Furthermore, for red algae, the reproductive structures are needed to be able to identify the sample to species. More research is needed to understand if sto- chastic events are structuring the epiphytic flora on single roots, or if other factors are involved. Eston et al. (1992) determined that on mangroves, early algal colonizers are also the final community, with no opportunistic species present and virtually no succession, as it has been reported for seagrass communities ( den Hartog 1971, 1987).

Cordeiro-Marino et al. (1992) reported that for the Caribbean basin, the phytocenosis associated with mangroves was dominated by green algae. In our study, 59.4

ACKNOWLEDGEMENTS

The samples were collected during a field trip financed by the Facultad de Ciencias, Universidad Nacional de Colombia, sede Bogotá. We thank Johanna Paola Echeverry Her- nández for her help in elaborating the map, and two anonymous reviewers to help improve the manuscript. The present contribution is part of the project codigo Hermes No. 33153. % of the species belonged to Rhodophyta, 29.7 % were Chlorophyta and only 10.8 % were Phaeophyceae. These percentages correspond to the average composition of the marine flora in the Caribbean (e.g. Taylor and Rhyne 1970, Betancourt-Fernandez and Herrera-Moreno 2001, Suárez 2005). Diaz-Pulido and Díaz-Ruiz (2003) reported, for the Rosario islands, a marine flora dominated by red algae (50.8 %) followed by green algae (39.7 %) and then brown algae (9.3 %). For the mangrove roots, we report a higher percentage of red algae, which also corresponds to the majority of the new records. Recent studies on the seaweeds of another region of the Colombian Caribbean (e.g. Albis-Salas and Gavio 2011, 2015, Ortiz and Gavio 2012, Gavio et al. 2013, 2015, Rincón-Díaz et al. 2014, 2018), registered a high number of red algal species previously overlooked.

The low number of brown algae ( Phaeophyceae) observed in this research is in agreement with other studies: López et al. (2009) found only three species of Phaeophyceae out of forty. Billah et al. (2016) reported only one Phaeophyceae of a total of eleven, while Pérez-Estrada et al. (2012) found a single species of brown algae of a total of 68. Rios et al. (2019) did not observe any brown algae on mangrove roots on the Caribbean coast of Panama.

The high diversity observed supports the importance of this community to the food web of mangrove ecosystems. This study by no means pretends to be comprehensive; considering the mangrove cover along the Caribbean coast of Colombia, more research is needed to address algal species diversity, distribution, seasonality and turn-over, to better understand the dynamics shaping these habitats.

AUTHORS PARTICIPATION

CESF collected the samples, identified the specimens, and wrote the manuscript. BG identified the specimens and wrote the manuscript. MJW identified some specimens and wrote the manuscript.

Figures

Figure 3. Some of the macroalgae registered in the study area. a-b. Dasya caraibica, a. Habit. Scale bar: 2 mm, b. Detail of partial rizoidal cortication. Scale bar: 100 um, c-d. Parviphycus setaceus, c. Habit. Scale bar: 200 um, d. cross section of thallus. Scale bar: 20 um, e-f. Wittrockiella salina, e..Habit Scale bar: 5 um, f. detail of cells. Scale bar: 5 um.