Physical contact interactions with scleractinian corals in hard substrate communities

Abstract

Shallow reefs are among the most diverse ecosystems, and their substrate is densely occupied by sessile organisms that frequently contact physically and interact mutually. Nevertheless, the relative importance of species abundance in shaping physical contacts in these ecosystems remains largely unknown. The aim of this study was to evaluate physical contact interactions, by using tools derived from the complex network theory, between hard corals and other benthic organisms in four areas along the Brazilian coast comprising coral reefs and rocky shores with different physical and biotic structures. It was also investigated whether interactions with corals occurred as expected by the abundance of the benthic organisms in each area, and whether corals belonging to families known as more aggressive interacted less with other organisms. In all areas, the abundance of both corals and contacting organisms directly influenced the abundance of interactions between benthic organisms, regardless of the physical or biological characteristics of the habitat and of the interacting organisms. In addition, coral species interacted more with the most abundant benthic group, the epilithic algal matrix, in all areas. Nevertheless, some evidence was found about biological mechanisms helping to explain the structure of the studied interactions, although to a lesser extent. The obtained networks presented high nestedness and connectance, but low modularity. These patterns indicate the low specificity of the studied interactions and reinforce the role of abundance as an important driver of contacts between sessile organisms in shallow hard bottom ecosystems.

Long-term effects of competition and environmental drivers on the growth of the endangered coral Mussismilia braziliensis (Verril, 1867)

“…From 2003 to 2008, Francini-Filho et al (2013) monitored the region’s benthic assemblages and failed to detect significant temporal changes in foliose macroalgae cover in both inshore and offshore reefs, despite recording consistent cross-shelf differences in macroalgal abundance. Although it is unclear whether the higher inshore macroalgal abundance (10–20% of reef cover) is a stable phase related to a long-standing high turbidity background, or a contemporary response to overfishing ( Freitas et al, 2011 ), increased macroalgal abundance implies a higher contact frequency with corals ( Grillo, Bonaldo & Segal, 2018 ). Poor land use and coastal development enhances sedimentation and reduce the overall vitality of reef systems, which is generally inversely related to distance offshore ( Dutra, Kikuchi & Leão, 2006 ).…”

Functional diversity patterns of reef fish, corals and algae in the Brazilian biogeographical province

“…Corals and algae diverged in their local functional diversity, possibly as a by-product of competition for space (Francini-Filho et al, 2013;Grillo et al, 2018;Lonzetti et al, 2022). Temperature represents environmental energy, and directly influences the metabolic processes, activity and growth of marine organisms, being a leading determinant of the distribution of species and traits in ecological communities (Barneche et al, 2019;Brown et al, 2004;Tittensor et al, 2010).…”

“…Such patterns are more likely to be driven by a similar response of the assemblages to sea surface temperature, or other variables such as width of the continental shelf (Cord et al, 2022). Corals and algae diverged in their local functional diversity, possibly as a by‐product of competition for space (Francini‐Filho et al, 2013; Grillo et al, 2018; Lonzetti et al, 2022).…”

“…Biotic interactions (ii) might be more intense among benthic organisms than fish so that corals and algae must compete for reef space leading to niche differentiation (Grillo et al, 2018; Lonzetti et al, 2022). Fish, in their turn, coexist in small reef areas where there are many functionally similar species (Barneche et al, 2019; Halpern & Floeter, 2008; Mouillot et al, 2014).…”

O invasor coral sol e mudanças climáticas: efeitos da temperatura na dispersão pelágica e competição interespecífica

“…Most sun coral species are originally distributed in the Indo-Pacific Ocean, which is the center of global marine diversity for several major taxa including fish, crustaceans and corals (Roberts et al 2002), with nothing less than 75% of the coral reefs worldwide . Brazilian coral reefs are significantly less diverse, including only fifteen scleractinian species , an evolutionary scenario that could supposedly have led endemic species to a diminished aggressiveness compared to species of coral reef communities from other locations (Grillo et al 2017). Thus, the more competitive environment in the Indo-Pacific has probably forced the selection of traits providing invasive sun-corals a competition advantage over scleractinians of the Southwestern Atlantic.…”