The role of geomorphic zonation in long-term changes in coral-community structure on a Caribbean fringing reef

Abstract

Ecological processes on coral reefs commonly have limited spatial and temporal scales and may not be recorded in their long-term geological history. The widespread degradation of Caribbean coral reefs over the last 40 years therefore provides an opportunity to assess the impact of more significant ecological changes on the geological and geomorphic structure of reefs. Here, we document the changing ecology of communities in a coral reef seascape within the context of its geomorphic zonation. By comparing basic ecological indices between historical and modern data we show that in 35 years the reef-front zone was transformed from a complex coral assemblage with a three-dimensional structure, to a size-homogenized and flattened one that is quasi indistinguishable from the adjacent non-accretional coral-ground zone. Today coral assemblages at Punta Maroma are characterized by the dominance of opportunistic species which are either tolerant to adverse environmental conditions, including sedimentation, or are known to be the first scleractinian species to recruit on disturbed reefs, implying they reflect a post-hurricane stage of adjustment. Despite an increase in similarity in ecological indices, the reef-front and coral-ground geomorphic zones still retain significant differences in coral assemblages and benthic habitat and are not homogeneous. The partial convergence of coral assemblages certainly has important consequences for the ecology and geological viability of the reef and its role in coastal protection, but environmental physical drivers continue to exert a fundamental role in the character and zonation of benthic communities of this reef seascape.

Characterizing Geomorphology of Mesophotic Coral Reef Ecosystems in the Southwestern Gulf of Mexico: Implications for Conservation and Management

“…There is a well-documented decline in shallow coral cover (CC) and structural complexity in the Caribbean region (Gardner et al, 2003;Alvarez-Filip et al, 2009;Medina-Valmaseda et al, 2020). For the SAVNP, there is also a decline in CC that has been documented since 1970s for shallow areas (<20 m), where the coral cover dropped from 50 to 18% (Chávez et al, 2007;Horta-Puga, 2007;Horta-Puga et al, 2015;Pérez-España et al, 2015).…”

“…Many studies have shown the global loss in live coral cover and critical degradation of coral reef ecosystems due to natural and anthropogenic disturbances (Gardner et al, 2003;Bellwood et al, 2004;Hoegh-Guldberg et al, 2007;Sweatman et al, 2011;De'ath et al, 2012;Gilmour et al, 2019). Evidence that the loss of live coral led to a drastic decline in the reef structural complexity has been shown for a region-wide scale in the Caribbean (Alvarez-Filip et al, 2009;Prachett et al, 2014;Bozec et al, 2015;Medina-Valmaseda et al, 2020). Such degradation trends generate uncertainty about the possible recovery of shallow coral reefs (Gardner et al, 2003) in which biodiversity, productivity and ecosystem services have been compromised (Moberg and Folke, 1999;Prachett et al, 2014).…”

Geomorphically controlled coral distribution in degraded shallow reefs of the Western Caribbean

“…It is well understood that pooling ecological data from local studies can lead to inaccurate results, predict potential pseudo-trends, or misinterpret ecological processes because of scale changes in the analysis ( Guzmán, Jackson & Weil, 1991 ; Karlson & Hurd, 1993 ; Williams et al, 2015b ; Medina-Valmaseda et al, 2020 ; Dietzel et al, 2020 ). This is because regional meta-analyses extrapolate from small-scale coral abundance and coverage data gathered with different primary objectives in mind.…”

Coverage Increases of Porites astreoides in Grenada Determined by Shifts in Size-Frequency Distribution

“…Scleractinian species in the Caribbean can be broadly characterized as having one of four life history strategies based on colony morphology, growth rate, and reproductive method [9]. These life history strategies are: (1) weedy (high recruitment, brooding reproduction); (2) stress tolerant (large colonies, slow growing, broadcast spawning); (3) competitive (framework, fast-growing, broadcast spawning); and (4) generalist Diversity 2021, 13, 288 2 of 15 (mix of traits of all other categories) [9]. Competitive species such as Acropora palmata or A. cervicornis, historically responsible for much of the complex framework building on Caribbean reefs, have experienced the most dramatic declines since the 1970s [10,11].…”

“…Non-framework building scleractinian species with a weedy life history strategy have proven successful in the region, in an era of rapid environmental change and have been among the few 'winners' on Caribbean reefs [12]. Species exhibiting this life history strategy, such as the mustard hill coral (Porites astreoides), have increased in mean percent cover on Caribbean reefs and now account for 16-72% of all living coral in Caribbean reef communities [13][14][15].…”