Introduction:

Marine macroalgae exhibit a wide variety of shapes and sizes, influencing habitat preferences for various organisms, including polychaetes and sipunculans.

Objective:

To evaluate the relationship between the richness and abundance of polychaetes and sipunculans with red, green, and brown marine macroalgae using specimens collected in Isla Cayo Serrana, Colombian Caribbean, deposited at the Colecciones Biológicas de la Universidad CES (CBUCES).

Methods:

To estimate the richness and abundance of polychaetes and sipunculans associated with macroalgae, the specimens were separated from each batch of macroalgae. Also, a χ2 test was performed to evaluate if there was an association between annelids and macroalgae. In addition, some morphological measurements were taken for green and red algae, and the relationship between algae morphological complexity and richness and abundance of polychaetes was assessed using Spearman’s correlation coefficient.

Results:

A total of 460 polychaetes and eight sipunculans were recorded in this study, distributed in 42 species. The polychaete family with the highest richness and abundance was Syllidae, whereas in sipunculans was Phascolosomatidae. Herein, we did not find an association between red, green, and brown macroalgae regarding the richness and abundance of polychaetes and sipunculans. However, a correlation (ρ 0.56-0.78, p < 0.03) was found between some morphological measurements of width, leaf area, wet weight, and displaced volume of green macroalgae of the genus Halimeda with the polychaetes richness and abundance. In contrast, there was no correlation between measurements of red macroalgae (Jania and Amphiroa) and polychaete richness and abundance (ρ between -0.1 and 0.39).

Conclusions:

This study underscores the relevance of specific morphological attributes of green macroalgae (Halimeda) in enhancing polychaete richness and abundance.