Resumen de Macroalgal community within a warm temperate/subtropical biogeographic transition zone in the western Atlantic Ocean
Karen G. Holloway Adkins, M. Dennis Hanisak
Little is known of the nearshore marine flora within the warm temperate/subtropical transition zone of the western Atlantic Ocean. The objectives of the present study were to describe a previously unexplored macroalgal community and determine if the species composition differed significantly with distance from an area of disturbance (channel), water depth, rock surface orientation, season, or mean water temperature. Samples (n = 1181) were composed primarily of turfed species of macroalgae, of which rhodophytes were the dominant algal group (88.2%), followed by chlorophytes (11.7%). Macroalgal groups and taxa associated with intense grazing (e.g., Ochrophyta, crustose rhodophytes, calcareous chlorophytes) were absent or present in <1.0% of samples. Thirty-five species of macroalgae were identified, nine of which persisted regardless of spatial location, sampling period, or temperature. The macroalgal community composition differed significantly for all factors tested; however, effect sizes of water depth and temperature were greatest. Overall results of this 2-yr study indicate the macroalgal flora within this biogeographic transition zone is primarily composed of eurythermic tropical species. This macroalgal community is utilized by diverse and abundant herbivorous fishes as well as the endangered green turtle [Chelonia mydas (Linnaeus, 1758)].
