Epibiont hydroids on beachcast Sargassum in the Mexican Caribbean

Abstract

Massive accumulations of pelagic species of Sargassum have generated recent social, economic and ecological problems along Caribbean shores. In the Mexican Caribbean, these events have prompted the study of diverse biological and ecological aspects of these macroalgae. However, studies on their associated biota, including Hydrozoa, remain scarce. This research provides important species observations in an area where data is lacking. The occurrence and percent cover of hydroids on Sargassum thalli collected on the beach at Puerto Morelos, Quintana Roo, Mexico from April 2018 to March 2019 was studied. Three pelagic species and morphotypes of Sargassum from this area were analyzed: Sargassum fluitans III, S. natans I and S. natans VIII, as well as a benthic species, S. polyceratium var. ovatum. A total of 14 taxa of hydroids, belonging to the superorders “Anthoathecata” and Leptothecata, were identified. In our study, more hydroid taxa were observed on axes of the different species of Sargassum than on leaves or aerocysts. In general, the greatest species richness of hydroids was observed from February to April. Results show that live hydrozoans attached to pelagic Sargassum are transported into the area. This should be considered in future management measures that address the recurring coastal abundance of Sargassum and its associated biota in the Caribbean region.

A Review of a Decade of Local Projects, Studies and Initiatives of Atypical Influxes of Pelagic Sargassum on Mexican Caribbean Coasts

“…Biological associations between Sargassum and various taxa vary in diversity and abundance according to the size of the Sargassum raft and its distance from the beach [3,4,35,36] Characterization of biological associations in open ocean, nearshore waters, and on the beach…”

“…In The four institutions with the highest number of experts are UNAM, SEMARNAT, CICY and CINVESTAV, with an average of fourteen experts per institution (Figure 9). In terms of geographical representation, the largest number of experts were located in Quintana Roo (89), followed by Mexico City (85) and Yucatan (35), while the rest were dispersed in seventeen other states of Mexico.…”

“…2, FOR PEER REVIEW 18 terms of geographical representation, the largest number of experts were located in Quintana Roo (89), followed by Mexico City (85) and Yucatan (35), while the rest were dispersed in seventeen other states of Mexico. At least one national or international collaboration was identified in 87 of the projects.…”

Commercial Potential of Pelagic Sargassum spp. in Mexico

“…Thus, the jurisdictional responsibility of the beached sargasso depends on the municipality and state government. Sargasso and its epibionts (Mendoza-Becerril et al, 2020), may contain heavy metals, such as arsenic (Rodríguez-Martínez et al, 2020) or other toxins [e.g., chlordecone, (Devault et al, 2021a)], but only if their concentrations are excessively high (which has yet to be established), can sargasso be considered hazardous, and as such become subject to federal regulations. Individual hotels are responsible for the maintenance of beach sections for which they have been granted concessions, which includes keeping it free from sargasso.…”

“…However, it has yet to be established whether sargasso from the Mexican Caribbean has similar results; in addition, the high arsenic content found in Caribbean sargasso (Rodríguez-Martínez et al, 2020) must be addressed before implementing its use as an animal feed. The presence of epiphytic communities (Salter et al, 2020), mostly calcifying hydroids (Mendoza-Becerril et al, 2020), should also be considered before using sargasso as livestock feed, as they may alter its nutritional composition.…”