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1. Large-scale invasion of western Atlantic mesophotic reefs by lionfish potentially undermines culling-based management

   https://doi.org/DOI 10.1007/s10530-016-1358-0  

   Andradi-Brown, Dominic A.; Vermeij, Mark J.; Slattery, Marc; Lesser, Michael; Bejarano, Ivonne; Appeldoorn, Richard; Goodbody-Gringley, Gretchen; Chequer, Alex D.; Pitt, Joanna M.; Eddy, Corey; et al (January 2017, Biological invasions)

   The detrimental effects of invasive lionfishes (Pterois volitans and Pterois miles) on western Atlantic shallow reefs are well documented, including declines in coral cover and native fish populations, with disproportionate predation on critically endangered reef fish in some locations. Yet despite individuals reaching depths[100 m, the role of mesophotic coral ecosystems (MCEs; reefs 30–150 m) in lionfish ecology has not been addressed. With lionfish control programs in most invaded locations limited to 30 mby diving restrictions, understanding the role of MCEs in lionfish distributions remains a critical knowledge gap potentially hindering conservation management. Here we synthesise unpublished and previously published studies of lionfish abundance and body length at paired shallow reef (0–30 m) and MCE sites in 63 locations in seven western Atlantic countries and eight sites in three Indo-Pacific countries where lionfish are native. Lionfish were found at similar abundances across the depth gradient from shallow to adjacent MCEs, with no difference between invaded and native sites. Of the five invaded countries where length data were available three had larger lionfish on mesophotic than shallow reefs, one showed no significant difference, while the fifth represented a recently invaded site. This suggests at least some mesophotic populations may represent extensions of natural ontogenetic migrations. Interestingly, despite their shallow focus, in many cases culling programs did not appear to alter abundance between depths. In general, we identify widespread invasive lionfish populations on MCE that could be responsible for maintaining high densities of lionfish recruits despite local shallow-biased control programs. This study highlights the need for management plans to incorporate lionfish populations below the depth limit of recreational diving in order to address all aspects of the local population and maximise the effectiveness of control efforts. 

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2. Conservation benefits of a large marine protected area network that spans multiple ecosystems

   https://doi.org/10.1111/cobi.14435  

   Smith, Joshua G; Lopazanski, Cori; Free, Christopher M; Brun, Julien; Anderson, Clarissa; Carr, Mark H; Claudet, Joachim; Dugan, Jenifer E; Eurich, Jacob G; Francis, Tessa B; et al (August 2025, Conservation Biology)

   Abstract Marine protected areas (MPAs) are widely implemented tools for long‐term ocean conservation and resource management. Assessments of MPA performance have largely focused on specific ecosystems individually and have rarely evaluated performance across multiple ecosystems either in an individual MPA or across an MPA network. We evaluated the conservation performance of 59 MPAs in California's large MPA network, which encompasses 4 primary ecosystems (surf zone, kelp forest, shallow reef, deep reef) and 4 bioregions, and identified MPA attributes that best explain performance. Using a meta‐analytic framework, we evaluated the ability of MPAs to conserve fish biomass, richness, and diversity. At the scale of the network and for 3 of 4 regions, the biomass of species targeted by fishing was positively associated with the level of regulatory protection and was greater inside no‐take MPAs, whereas species not targeted by fishing had similar biomass in MPAs and areas open to fishing. In contrast, species richness and diversity were not as strongly enhanced by MPA protection. The key features of conservation effectiveness included MPA age, preimplementation fisheries pressure, and habitat diversity. Important drivers of MPA effectiveness for single MPAs were consistent across MPAs in the network, spanning regions and ecosystems. With international targets aimed at protecting 30% of the world's oceans by 2030, MPA design and assessment frameworks should consider conservation performance at multiple ecologically relevant scales, from individual MPAs to MPA networks. 

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3. Global community breaks at 60 m on mesophotic coral reefs

   https://doi.org/10.1111/geb.12940  

   Lesser, Michael P.; Slattery, Marc; Laverick, Jack H.; Macartney, Keir J.; Bridge, Tom C.; Pandolfi, ed., John (June 2019, Global Ecology and Biogeography)

   Abstract AimMesophotic coral ecosystems (MCEs) are unique communities that support a high proportion of depth‐endemic species distinct from shallow‐water coral reefs. However, there is currently little consensus on the boundaries between shallow and mesophotic coral reefs and between upper versus lower MCEs because studies of these communities are often site specific. Here, we examine the ecological evidence for community breaks, defined here as species loss, in fish and benthic taxa between shallow reefs and MCEs globally. LocationGlobal MCEs. Time period1973–2017. Major taxa studiedMacrophytes, Porifera, Scleractinia, Hydrozoa, Octocorallia, Antipatharia and teleost fishes. MethodsWe used random‐effects models and breakpoint analyses on presence/absence data to identify regions of higher than expected species loss along a depth gradient of 1–69 m, based on a meta‐analysis of 26 studies spanning diverse photoautotrophic and heterotrophic taxa. We then investigated the extent to which points of high faunal turnover can be explained by environmental factors, including light, temperature and nutrient availability. ResultsWe found evidence for a community break, indicated by a significant loss of shallow‐water taxa, at ~ 60 m across several taxonomically and functionally diverse benthic groups and geographical regions. The breakpoint in benthic composition is best explained by decreasing light, which is correlated with the optical depths between 10 and 1% of surface irradiance. A concurrent shift in the availability of nutrients, both dissolved and particulate organic matter, and a shift from photoautotroph to heterotroph‐dominated assemblages also occurs at ~ 60 m depth. Main conclusionsWe found evidence for global community breaks across multiple benthic taxa at ~ 60 m depth, indicative of distinct community transitions between shallow and mesophotic coral ecosystems. Changes in the underwater light environment and the availability of trophic resources along the depth gradient are the most parsimonious explanations for the observed patterns. 

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4. Depth-dependent trophic strategies of Caribbean sponges on mesophotic coral reefs

   https://doi.org/10.3354/meps14059  

   Macartney, KJ; Pankey, MS; Clayshulte Abraham, A; Slattery, M; Lesser, MP (July 2022, Marine Ecology Progress Series)

   Mesophotic coral reef ecosystems (MCEs) are characterized by gradients in irradiance, temperature and trophic resources. As depth increases on Caribbean mesophotic reefs, particulate organic matter increases while dissolved organic matter decreases, and the increase in particulate organic matter is directly related to the increase in sponge abundances and growth rates on MCEs. To further understand the trophic ecology of sponges, changes in microbiome composition and function, stable isotopic composition and proximate biochemical composition of 4 Caribbean reef sponges ( Amphimedon compressa , Agelas tubulata , Plakortis angulospiculatus and Xestospongia muta) were quantified along a shallow to mesophotic depth gradient on Grand Cayman Island. Increases in δ 15 N for all sponges were observed as depth increased, indicating an increasing reliance on heterotrophic food resources. Species-specific changes in symbiotic microbial community composition were also observed as depth increased, and the predicted functional genes associated with nitrogen and carbon cycling showed species-specific changes between depths. Regardless of species-specific changes in microbiome community structure or function, or whether sponges were classified as high microbial or low microbial abundance, sponges increased their consumption of particulate organic matter with increasing depth into the lower mesophotic zone. 

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5. Incident light and morphology determine coral productivity along a shallow to mesophotic depth gradient

   https://doi.org/10.1002/ece3.8066  

   Lesser, Michael P.; Slattery, Marc; Mobley, Curtis D. (August 2021, Ecology and Evolution)

   Abstract While the effects of irradiance on coral productivity are well known, corals along a shallow to mesophotic depth gradient (10–100 m) experience incident irradiances determined by the optical properties of the water column, coral morphology, and reef topography.Modeling of productivity (i.e., carbon fixation) using empirical data shows that hemispherical colonies photosynthetically fix significantly greater amounts of carbon across all depths, and throughout the day, compared with plating and branching morphologies. In addition, topography (i.e., substrate angle) further influences the rate of productivity of corals but does not change the hierarchy of coral morphologies relative to productivity.The differences in primary productivity for different coral morphologies are not, however, entirely consistent with the known ecological distributions of these coral morphotypes in the mesophotic zone as plating corals often become the dominant morphotype with increasing depth.Other colony‐specific features such as skeletal scattering of light, Symbiodiniaceae species, package effect, or tissue thickness contribute to the variability in the ecological distributions of morphotypes over the depth gradient and are captured in the metric known as the minimum quantum requirements.Coral morphology is a strong proximate cause for the observed differences in productivity, with secondary effects of reef topography on incident irradiances, and subsequently the community structure of mesophotic corals. 

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