Why do mesophotic coral ecosystems have to be protected?

Abstract

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Depth-dependent parental effects create invisible barriers to coral dispersal

“…Taken together with the possibly narrower thermal tolerance 19 and reduced fertility and reproductive performance at the mesophotic depths 65 , deep-water populations of some "depth-generalist" species may reflect marginal populations, which may be dependent to some extent on larval supply from shallower populations. These, in turn, may indicate that deep-water populations might be more fragile than commonly assumed, and thus warrant immediate conservation considerations in their own right [66][67][68] . Nonetheless, in regions where shallow reefs are already severely degraded, the potential reproductive output and subsequent larval success of locally intermediate-or mesophotic-depth populations may exceed that of the shallow-reef populations 29,69 .…”

Deep reefs are not refugium for shallow‐water fish communities in the southwestern Atlantic

“…As shallow-water coral reef ecosystems are gradually degraded by human activities, identifying areas where biodiversity can be maintained has become a conservation priority worldwide Soares et al, 2020). These areas comprise marginal reefs such as turbid-zone and high-temperature areas, macrotidal reefs, tide pools, volcanic CO 2 vents, ojos (low pH springs), areas with submarine groundwater discharge, mangrove systems, upwelling areas, temperate mesophotic ecosystems, mesophotic coral ecosystems, and coldwater coral ecosystems (Camp et al, 2018;Enochs et al, 2020;Soares et al, 2021).…”

“…The deep reefs are closely linked to shallow reef areas, usually forming a contiguous or semi-contiguous belt of habitats along a depth gradient (Lindfield et al, 2016). However, unlike the shallow reefs (<30 m depth), the deep reefs are presumably less exposed to ocean warming and other human pressures such as coastal pollution, overfishing, and nonregulated tourism (Hoegh-Guldberg & Bruno, 2010;Mies et al, 2020;Mora et al, 2011;Soares et al, 2020), leading researchers to postulate that deep reefs could act as depth refuge, refugium, or resilience area for reef biota in face of a massive loss of shallow reefs ("deep reef refugia hypothesis" sensu Bongaerts et al, 2010; see also Glynn, 1996;Kahng et al, 2010;Loya et al, 2016). By depth refuge, we mean a depth range that provides short-term buffering or shelter for one or multiple species or a biological community against a particular disturbance episode; depth refugium, a depth range that provides a long-term buffering or shelter for one or multiple species or a biological community against a particular or multiple disturbance types; and resilience area, a depth range that harbors one or multiple species or a biological community that is/are resilient over the long term to a particular or multiple disturbance types (sensu Bongaerts & Smith, 2019).…”

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

“…Also undersampled are Brazil's mesophotic ecosystems (deep‐water habitats), which are home to the most extensive beds of rhodoliths in the world. Studies on the cyanobacteria and algal floras of these regions are urgently needed (Soares & al., 2019, 2020; Spalding & al., 2019; Paton & al., 2020).…”