Human activities influence benthic community structure and the composition of the coral-algal interactions in the central Maldives

The Dynamics of Coral-Algal Interactions in Space and Time on the Southern Great Barrier Reef

“…Our results show that the greatest number of coralalgal interactions on Heron reef occur when coral cover is ∼50%, macroalgal cover is ∼20%, and abiotic cover remains less than ∼30%. Even though macroalgal abundance fluctuated naturally from as low as 1% to as high as 60% cover, an increase in macroalgal cover over 20% did not translate into an increase in coral-algal interactions, which is similar to some previous studies (Jompa and McCook, 2003a;Brown et al, 2017) and in contrast to others (Smith et al, 1981;Lewis, 1986;Hughes, 1989Hughes, , 1994Bonaldo and Hay, 2014). Instead, coral cover was the best predictor of the coral-algal interaction frequency.…”

“…Since competition for space takes place only between neighbors, coral-algal interactions would be expected to occur more often when abiotic space is low (Brown et al, 2017) and coral (Connell et al, 2004) or macroalgal cover are high (Smith et al, 1981;Lewis, 1986;Hughes, 1989Hughes, , 1994Bonaldo and Hay, 2014). Our results show that the greatest number of coralalgal interactions on Heron reef occur when coral cover is ∼50%, macroalgal cover is ∼20%, and abiotic cover remains less than ∼30%.…”

“…Benthic community composition and frequencies of coralalgal contact were recorded using the method described by Brown et al (2017). At each site, 3 × 15 m transects were established coursing north, east and west from a central reference point.…”

“…"Other invertebrates" included organisms such as soft corals, giant clams, sea cucumbers, and all other invertebrates (i.e., sponges, ascidians). "Abiotic substrate" was divided into sand/sediment, coral rubble, recently dead hard coral, and "bare" rock (i.e., epithetic algal community with turf height <3 mm) (see definitions in Brown et al, 2017).…”

“…Along the same transects, a 1 m belt (0.5 m on either side) of the transect line was examined and any coral colonies physically touching macroalgae were documented (Brown et al, 2017). A single coral colony (i.e., corals with more than one corallite) could be involved in multiple competitive interactions with different macroalgal taxa or groups (Swierts and Vermeij, 2016).…”