Coral identity underpins architectural complexity on Caribbean reefs

Abstract

The architectural complexity of ecosystems can greatly influence their capacity to support biodiversity and deliver ecosystem services. Understanding the components underlying this complexity can aid the development of effective strategies for ecosystem conservation. Caribbean coral reefs support and protect millions of livelihoods, but recent anthropogenic change is shifting communities toward reefs dominated by stress-resistant coral species, which are often less architecturally complex. With the regionwide decline in reef fish abundance, it is becoming increasingly important to understand changes in coral reef community structure and function. We quantify the influence of coral composition, diversity, and morpho-functional traits on the architectural complexity of reefs across 91 sites at Cozumel, Mexico. Although reef architectural complexity increases with coral cover and species richness, it is highest on sites that are low in taxonomic evenness and dominated by morpho-functionally important, reef-building coral genera, particularly Montastraea. Sites with similar coral community composition also tend to occur on reefs with very similar architectural complexity, suggesting that reef structure tends to be determined by the same key species across sites. Our findings provide support for prioritizing and protecting particular reef types, especially those dominated by key reef-building corals, in order to enhance reef complexity.

Complex reef architecture supports more small-bodied fishes and longer food chains on Caribbean reefs

“…For example, in the Caribbean, rapid declines in live coral cover have been accompanied by a shift in communities towards reefs dominated by stress-resistant and less architecturally complex corals (e.g., Hughes 1994, Green et al 2008. In this region, mid-water reefs are now dominated by stressresistant corals such as Porites and Agaricia which provide consistently less architectural-complex reefs in comparison to Montastraea-dominated sites (Alvarez-Filip et al 2011b). These shifts in coral community composition can potentially have severe consequences for associated reef fishes; hence there is a pressing need to understand the response of fish communities to the changes in coral community composition and associated loss of reef complexity.…”

Spatiotemporal variations of live coral cover in the northern Mesoamerican Reef System, Yucatan Peninsula, Mexico

“…Orbicella spp., Acropora palmata). Therefore, the direction of change in the structure of species assemblages towards smaller colonies and reduced structural complexity could affect the ecosystem functioning (Álvarez-Filip et al 2011, Álvarez-Filip et al 2013, Perry et al 2014.…”

“…support the functions of structural complexity and accretion, which in turn promote the stability and diversity of other species in these ecosystems Precht 2001, Rodríguez-Zaragoza andArias-González 2015). It is possible that changes in the abundance of some key species have consequences in the architectural complexity of coral reefs and thus in the ecosystem functioning, even if the overall coral cover remains stable (Green et al 2008, Álvarez-Filip et al 2011. Therefore, a long-term evaluation is essential in order to better understand the natural population dynamics (West and Salm 2003), how species respond to natural and anthropogenic stresses (Hughes et al 2003) and, indirectly, the resistance and resilience of coral reef ecosystems through the evaluation of their functional groups (Bellwood et al 2004, Petchey andGaston 2006).…”

Fish community structure on coral habitats with contrasting architecture in the Tropical Eastern Pacific

“…it appears that the current loss of massive corals, the architectural flattening of the reefscape and community shifts towards monotonous stands of stress-resistant coral taxa (e.g., Pocillopora spp. ), would pose a risk mainly to the large and carnivorous species in the fish assemblage (Pratchett et al, 2008;Alvarez-Filip et al, 2011b;Kerry & Bellwood, 2012). Massive coral species, which are in fact very vulnerable to natural and anthropogenic disturbances (Jones & Syms, 1998), require critical protection not only to guarantee the complexity of the reefscape architecture, but to support the large fishes from high trophic levels and thus maintain the diversity and evenness of the fish assemblage.…”

“…For example, branching coral communities with many interstices are often used by small reef fishes for shelter (Beukers & Jones, 1997), while tabular corals congregate larger reef fishes that seek concealment for ambush predation or shade from sunlight (Kerry & Bellwood, 2012). Studying fish-habitat associations also provides insights into the effects of decreased structural complexity as a consequence of habitat degradation (Pratchett et al, 2008;Benfield, Baxter, Guzman & Mair, 2008;Alvarez-Filip, Dulvy, Côté, Watkinson & Gill, 2011b). Coral morphology is, however, a measure of architectural complexity usually not considered in coral reef fish studies, as most methods designed to assess the habitat complexity of coral communities (Risk, 1972;McCormick 1994;Wilson, Graham & Polunin, 2007;Wedding, Friedlander, McGranaghan, Yost & Monaco, 2008) involve the use of quantitative indices that conceal the role of dominant coral species and their associated morphological and functional traits (Luckhurst & Luckhurst, 1978;Jones & Syms, 1998;Kerry & Bellwood, 2012).…”