The importance of coastal gorgonians in the blue carbon budget

Abstract

Terrestrial (trees, shrubs) and marine (seaweeds and seagrasses) organisms act as carbon (C) sinks, but the role of benthic suspension feeders in this regard has been largely neglected so far. Gorgonians are one of the most conspicuous inhabitants of marine animal forests (mainly composed of sessile filter feeders); their seston capture rates influence benthic-pelagic coupling processes and they act as C sinks immobilizing carbon in their long-living structures. Three gorgonian species (Paramuricea clavata, Eunicella singularis and Leptogorgia sarmentosa) were studied coupling data of population size structure, biomass and spatial distribution in a NW Mediterranean area (Cap de Creus, Spain) with feeding, respiration and growth rates. In the study area, we calculated that P. clavata sequestered 0.73 ± 0.71 g C m−2 year−1, E. singularis 0.73 ± 0.89 g C m−2 year−1 and L. sarmentosa 0.03 ± 0.02 g C m−2 year−1. To our knowledge, this is the first attempt to calculate the importance as C sinks of gorgonian species that we consider as a starting point to estimate the importance of marine animal forests in C sequestration, and to ensure appropriate management and protection especially in areas and at depths where they are concentrated.

Historical record of Corallium rubrum and its changing carbon sequestration capacity: A meta-analysis from the North Western Mediterranean

“…These kinds of estimates of carbon flux and carbon sink are available in the literature for different benthic systems, but they are still scarce for CR. For example, estimates for seagrass meadows carbon sink gives 6,700 kg C ha -1 y -1 [103], for Paramuricea clavata and Eunicella singularis 2,000 kg C ha -1 y -1 both, and for Leptogorgia sarmentosa 0.008 kg C ha -1 y -1 [116], all of them substantially higher than our results (158 and 304 g C ha -1 y -1 ). Again, the difference might be due to the fact that we only considered basal diameter growth.…”

“…Again, the difference might be due to the fact that we only considered basal diameter growth. Regarding the C flux, Coppari et al (2019) [116] calculated 1,000 kg C ha -1 for P. clavata and E. singularis, and 0.02 kg C ha -1 for L. sarmentosa, which is the closest species to CR in C flux magnitude (0.0135 and 0.0035 kg C ha -1 in this study).…”

Climate change transforms the functional identity of Mediterranean coralligenous assemblages

“…2017; Coppari et al . 2019). Thus, their decline in MHW‐impacted assemblages in benefit of other traits (e.g.…”

“…2017; Coppari et al . 2019). In benthic ecosystems, the three‐dimensionality of organisms plays a fundamental role in the organisation, function and resilience.…”

Resilience of Octocoral Forests to Catastrophic Storms

“…At high population densities, Caribbean octocorals form underwater forests 50 that alter environmental conditions, such as light, currents, and sedimentation, beneath their canopy, and create habitat utilized by many species 50,65,66 . Octocoral forests, unlike scleractinians, do not build hard, wave resistant structures, but they provide some of the ecosystem services formerly supported by scleractinians (e.g., providing fish habitat 67 , acting as a carbon sink 68 and generating sediments 69 ). In the present environmental conditions, octocoral-dominated communities may constitute the "new normal" for shallow Caribbean reefs.…”