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4 pages, 205 KiB

Open AccessEditorial

Mesophotic Ecosystems: The Link between Shallow and Deep-Sea Habitats

by Gal Eyal and Hudson T. Pinheiro

Diversity 2020, 12(11), 411; https://doi.org/10.3390/d12110411 - 28 Oct 2020

Cited by 15 | Viewed by 3131

Abstract

Mesophotic ecosystems (MEs) are characterized by the presence of light-dependent organisms, found at depths ranging from ~30 to 150 m in temperate, subtropical and tropical regions. These communities occasionally create massive reef structures with diverse but characteristic morphologies, which serve as the framework [...] Read more.

Mesophotic ecosystems (MEs) are characterized by the presence of light-dependent organisms, found at depths ranging from ~30 to 150 m in temperate, subtropical and tropical regions. These communities occasionally create massive reef structures with diverse but characteristic morphologies, which serve as the framework builders of those ecosystems. In many localities, MEs are physically linked with shallow and deep-sea habitats, and while taxa from both environments share this space, a unique and endemic biodiversity is also found. The main MEs studied to date are the mesophotic coral ecosystems (MCEs) and the temperate mesophotic ecosystems (TMEs), which have received increased attention during the last decade. As shallow coral reef ecosystems are among the most threatened habitats on Earth, the potential of MEs to act as refugia and contribute to the resilience of the whole ecosystem has been a subject of scrutiny. New technologies and methods have become more available to study these deeper parts of the reef ecosystems, yielding many new discoveries. However, basic gaps in knowledge remain in our scientific understanding of the global diversity of MEs, limiting our ability to recognize biogeographic patterns and to make educated decisions for the management and conservation of these ecosystems. Full article

(This article belongs to the Special Issue Biodiversity of Mesophotic Ecosystems)

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16 pages, 4128 KiB

Open AccessFeature PaperArticle

Benthic Characterization of Mesophotic Communities Based on Optical Depths in the Southern Mexican Pacific Coast (Oaxaca)

by Miguel Ángel Pérez-Castro, Gal Eyal, Gerardo Esteban Leyte-Morales, Gustavo Hinojosa-Arango and Susana Enríquez

Diversity 2023, 15(4), 531; https://doi.org/10.3390/d15040531 - 6 Apr 2023

Cited by 2 | Viewed by 1946

Abstract

The distinction between shallow coral reefs and mesophotic coral ecosystems (MCEs) has not been fully clarified yet. The original definition of MCEs, by depths of 30–150 m, fixes their bathymetrical limits and fails to accommodate environmental and biological variation. Recent studies have indicated [...] Read more.

The distinction between shallow coral reefs and mesophotic coral ecosystems (MCEs) has not been fully clarified yet. The original definition of MCEs, by depths of 30–150 m, fixes their bathymetrical limits and fails to accommodate environmental and biological variation. Recent studies have indicated that water transparency and light availability may explain why MCEs do not occur at fixed depths but vary among localities. This study aimed to evaluate the presence and distribution of MCEs, along the central coast of Oaxaca, through optical depths and the associated benthic community. Using MODIS-Aqua satellite data (Kd490), we estimated the mesophotic optical depths monthly (z10%, z1%, z0.1%), over the last four years. In addition, to characterize benthic community structure, we conducted underwater photo quadrat surveys at two locations on the southern Mexican Pacific coast from 10 to 55 m depth. Significant differences between depths and locations were found in benthic communities. Furthermore, the lower distribution of photosynthetic taxa was different between the two locations but indicative to the z10% and z1% in both cases. Those differences were associated with the upwelling season, which reduces, drastically and differentially, the light availability for benthic communities between the two locations and limits the development of MCEs on the central coast of Oaxaca. Full article

(This article belongs to the Special Issue Biodiversity of Mesophotic Ecosystems)

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19 pages, 2387 KiB

Open AccessFeature PaperArticle

The Hidden Diversity of Temperate Mesophotic Ecosystems from Central Chile (Southeastern Pacific Ocean) Assessed through Towed Underwater Videos

by Ana Navarro Campoy, Alejandro Pérez-Matus, Evie A. Wieters, Rodrigo Alarcón-Ireland, Vladimir Garmendia, Ricardo Beldade, Sergio A. Navarrete and Miriam Fernández

Diversity 2023, 15(3), 360; https://doi.org/10.3390/d15030360 - 2 Mar 2023

Cited by 7 | Viewed by 3003

Abstract

The largely unexplored diversity in temperate mesophotic ecosystems (TME, ~30–150 m depth) has attracted much attention over the past years. However, the number of studies and knowledge of TME diversity and ecology remains limited and geographically restricted. The absence of information on how [...] Read more.

The largely unexplored diversity in temperate mesophotic ecosystems (TME, ~30–150 m depth) has attracted much attention over the past years. However, the number of studies and knowledge of TME diversity and ecology remains limited and geographically restricted. The absence of information on how assemblages vary across environmental gradients and with depth for most regions also limits our capacity to delimit conservation areas and devise management plans effectively. This study focuses on TME from central Chile and describes the depth distribution of reef fishes and benthic invertebrates and algae for the first time. Through the analysis of towed underwater video surveys between 4.7–95.5 m in multiple sites, we show that total reef fish density and richness decrease with depth but increase with local topographic complexity. The depth-related density varies among fish species and trophic groups, and it reverses in the case of Sebastes oculatus, which increases in density with depth. Sponges and gorgonians dominate benthic assemblages below 20 m depth, and brachiopods and anemones increase below 40 and 60 m, respectively. Some of these species form animal forests which, to some extent, replace the shallow-water kelp forests as structural habitat providers. Nevertheless, the reef fish and benthic community do not show a clear structure with depth or across studied sites. We highlight the urgency to intensify and expand the quantitative characterization of these communities, through this and other methodologies, to better define ecological patterns and advance towards conservation plans for TME, including the Souteastern Pacific region. Full article

(This article belongs to the Special Issue Biodiversity of Mesophotic Ecosystems)

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21 pages, 3381 KiB

Open AccessArticle

Mesophotic Reefs of the Largest Brazilian Coastal Protected Area: Mapping, Characterization and Biodiversity

by Pedro H. C. Pereira, Gislaine V. Lima, Julia C. Araujo, Erandy Gomes, Luís G. F. Côrtes, Antonio V. Pontes, Radharanne Recinos, Andrei Cardoso, José C. Seoane and Camila C. P. Brito

Diversity 2022, 14(9), 760; https://doi.org/10.3390/d14090760 - 15 Sep 2022

Cited by 2 | Viewed by 2619

Abstract

Mesophotic reefs are poorly known worldwide despite their great ecological relevance and management importance for coral reef conservation strategies. To aid in filling this gap, we conducted a pioneering, large-scale survey, covering a total of around 315 miles in length, in the largest [...] Read more.

Mesophotic reefs are poorly known worldwide despite their great ecological relevance and management importance for coral reef conservation strategies. To aid in filling this gap, we conducted a pioneering, large-scale survey, covering a total of around 315 miles in length, in the largest Brazilian coastal Marine Protected Area (MPA) Costa dos Corais. From the digital bathymetry model (30 to 50 m depth) generated by a multibeam echo sounder, we selected areas of greater geomorphological diversity for a detailed investigative expedition of mesophotic ecosystems. Various sampling techniques were used: single-beam echo sounders for detailing the relief, a remotely operated underwater vehicle (ROV) for habitat type investigation, baited remote underwater video (BRUV) for collecting images of the fish community, and scuba diving to perform transects describing the benthic and fish community. We analyzed reef environments from 20 to 68 m deep. As a result, we present the mapping and geomorphological characterization of two compartments of mesophotic reefs at 21–45 m depth and an image library of mesophotic ecosystems with the species description and indications of whether it is a new record in the region. Biodiversity data were collected covering eight species of sponges, with greater abundance for Ircinia spp., Aplysina spp., and Xestospongia muta; eight from corals, mainly Siderastrea spp. And Montastrea cavernosa; and 68 species of reef fish, with the Labridae family (including Scarinae—11 species) being the richest. Our results demonstrate the importance of mesophotic reefs for MPA Costa dos Corais reef biodiversity and, with that, the need to protect these areas through the application of local conservation strategies, such as the creation of “no-take zones”. Full article

(This article belongs to the Special Issue Biodiversity of Mesophotic Ecosystems)

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16 pages, 2304 KiB

Open AccessArticle

Phylogeography of Mesophotic Coral Ecosystems: Squirrelfish and Soldierfish (Holocentriformes: Holocentridae)

by Joshua M. Copus, Cameron A. J. Walsh, Mykle L. Hoban, Anne M. Lee, Richard L. Pyle, Randall K. Kosaki, Robert J. Toonen and Brian W. Bowen

Diversity 2022, 14(8), 691; https://doi.org/10.3390/d14080691 - 21 Aug 2022

Cited by 2 | Viewed by 2616

Abstract

Mesophotic coral ecosystems (MCEs: ~30 to 100+ m depth) may be older and more stable than shallow coral ecosystems that are more prone to disturbances in both the long term (glacial sea level cycles) and short term (heavy weather and anthropogenic activities). Here, [...] Read more.

Mesophotic coral ecosystems (MCEs: ~30 to 100+ m depth) may be older and more stable than shallow coral ecosystems that are more prone to disturbances in both the long term (glacial sea level cycles) and short term (heavy weather and anthropogenic activities). Here, we assess the phylogeography of two MCE fishes, the soldierfish Myripristis chryseres (N = 85) and the squirrelfish Neoniphon aurolineatus (N = 74), with mtDNA cytochrome oxidase C subunit I. Our goal is to resolve population genetic diversity across the Central and West Pacific and compare these patterns to three shallow-reef species in the same taxonomic family (Holocentridae). Significant population structure (Φ_ST = 0.148, p = 0.01) was observed in N. aurolineatus, while no structure was detected in M. chryseres (Φ_ST = −0.031, p = 0.83), a finding that matches the shallow-water congener M. berndti (Φ_ST = −0.007, p = 0.63) across the same range. Nucleotide diversity in the MCE fishes was low (π = 0.0024–0.0028) compared to shallow counterparts (π = 0.003–0.006). Coalescence times calculated for M. chryseres (~272,000 years) and N. aurolineatus (~284,000 years) are more recent or comparable to the shallow-water holocentrids (~220,000–916,000 years). We conclude that the shallow genetic coalescence characteristic of shallow-water marine fishes cannot be attributed to frequent disturbance. We see no evidence from holocentrid species that MCEs are older or more stable habitats. Full article

(This article belongs to the Special Issue Biodiversity of Mesophotic Ecosystems)

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15 pages, 5713 KiB

Open AccessArticle

Mapping Ecological Units in Mesophotic Coral Ecosystems of San Andrés Island (Southwestern Caribbean)

by Katherine Mejía-Quintero, Cristina Cedeño-Posso, Santiago Millán and Luis Chasqui

Diversity 2022, 14(8), 679; https://doi.org/10.3390/d14080679 - 19 Aug 2022

Cited by 2 | Viewed by 2051

Abstract

To map ecological units in mesophotic coral ecosystems on the western side of San Andrés Island (Colombia) considering biotic components and geomorphic zonation among 30–140 m deep, 27 video transects were done using an ROV. In total, 14 h of video were recorded [...] Read more.

To map ecological units in mesophotic coral ecosystems on the western side of San Andrés Island (Colombia) considering biotic components and geomorphic zonation among 30–140 m deep, 27 video transects were done using an ROV. In total, 14 h of video were recorded and 5742 still images were extracted from them, from which 753 met quality criteria for bottom coverage and organisms’ abundance estimations. These estimates were calculated from images through the Planar-Point Intercept method (PPI) using a 1 m × 0.5 m quadrant gridded 0.1 m × 0.1 m. CLUSTER, SIMPROF, and SIMPER analysis of benthic composition considering depth ranges in the group’s formation were done. The clusters formed were simplified and generalized using a color matrix to support the mapping process. Two geomorphological units were found, the deep reef terrace (30–60 m) and the reef slope (60–357 m), overlapping with five ecological units spanning 268 ha. The units Bioturbed sediments–Calcareous algae, Octocorals–Mixed corals, and Octocorals–Sponges sited on the deep reef terrace have been previously described in the shallow waters of the island, and the units Octocorals–Sponges–Antipatharians and Encrusting Sponges sited on the reef slope are described as new here. These findings contribute to the knowledge of Caribbean mesophotic coral ecosystems and are useful to update the Colombian coral reef atlas. Full article

(This article belongs to the Special Issue Biodiversity of Mesophotic Ecosystems)

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18 pages, 3158 KiB

Open AccessArticle

Ecological Links between Pelagic and Mesophotic Reef Fishes in an Oceanic Archipelago of the Equatorial Atlantic Ocean

by Caio Ribeiro Pimentel, Hudson T. Pinheiro, Tommaso Giarrizzo, Ronaldo B. Francini-Filho, José Amorim Reis-Filho, Luiz A. Rocha, Carlos Eduardo L. Ferreira, Moysés Cavichioli Barbosa and Jean-Christophe Joyeux

Diversity 2022, 14(4), 273; https://doi.org/10.3390/d14040273 - 5 Apr 2022

Cited by 5 | Viewed by 2750

Abstract

Geographic isolation, a relatively low species richness and high endemism make oceanic islands excellent natural laboratories for ecological and evolutionary studies. Here we used Baited Remote Underwater stereo-Video systems (stereo-BRUVS) to investigate the taxonomic, trophic and size structures of fish assemblages from pelagic [...] Read more.

Geographic isolation, a relatively low species richness and high endemism make oceanic islands excellent natural laboratories for ecological and evolutionary studies. Here we used Baited Remote Underwater stereo-Video systems (stereo-BRUVS) to investigate the taxonomic, trophic and size structures of fish assemblages from pelagic and mesophotic reef ecosystems in the smallest archipelago of the equatorial Atlantic Ocean, the Saint Peter and Saint Paul’s Archipelago (SPSPA). The occurrence of steep reef walls favors studies on the ecological connections between pelagic and reef ecosystems. We performed five pelagic stereo-BRUVS deployments and fourteen benthic stereo-BRUVS deployments, totaling 1440 min of footage. We recorded 14 species from eight families in the pelagic ecosystem, with Carangidae and Balistidae as the most diverse families. The most abundant species were Elagatis bipinnulata (Quoy and Gaimard, 1825), Melichthys niger (Bloch, 1786), and Caranx crysos (Mitchill, 1815), which together accounted for over 75% of the total relative abundance. The carnivores were the most diverse and abundant trophic group. On the mesophotic reefs, 41 taxa were recorded, with carnivores and planktivores being the most diverse, whereas omnivores were the most abundant. Here, the most abundant species were M. niger, Azurina multileneata, Chromis vanbebberae, Seriola rivoliana, Caranx lugubris and Stegastes sanctipauli. Nine species were recorded in both ecosystems, with Melichthys niger, Caranx lugubris and S. rivoliana being the main species linking them (i.e., occurring in both). These species are known to forage in both pelagic and mesophotic reef ecosystems, and thus represent potential ecological links between them. Such links combined with the endangered status of some species, suggest the need for an integrated management strategy in this remote archipelago. Full article

(This article belongs to the Special Issue Biodiversity of Mesophotic Ecosystems)

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9 pages, 1652 KiB

Open AccessArticle

Mesophotic Gorgonian Corals Evolved Multiple Times and Faster Than Deep and Shallow Lineages

by Juan A. Sánchez, Fanny L. González-Zapata, Carlos Prada and Luisa F. Dueñas

Diversity 2021, 13(12), 650; https://doi.org/10.3390/d13120650 - 7 Dec 2021

Cited by 7 | Viewed by 3859

Abstract

Mesophotic Coral Ecosystems (MCEs) develop on a unique environment, where abrupt environmental changes take place. Using a time-calibrated molecular phylogeny (mtDNA: mtMutS), we examined the lineage membership of mesophotic gorgonian corals (Octocorallia: Cnidaria) in comparison to shallow and deep-sea lineages of the wider [...] Read more.

Mesophotic Coral Ecosystems (MCEs) develop on a unique environment, where abrupt environmental changes take place. Using a time-calibrated molecular phylogeny (mtDNA: mtMutS), we examined the lineage membership of mesophotic gorgonian corals (Octocorallia: Cnidaria) in comparison to shallow and deep-sea lineages of the wider Caribbean-Gulf of Mexico and the Tropical Eastern Pacific. Our results show mesophotic gorgonians originating multiple times from old deep-sea octocoral lineages, whereas shallow-water species comprise younger lineages. The mesophotic gorgonian fauna in the studied areas is related to their zooxanthellate shallow-water counterparts in only two clades (Gorgoniidae and Plexauridae), where the bathymetrical gradient could serve as a driver of diversification. Interestingly, mesophotic clades have diversified faster than either shallow or deep clades. One of this groups with fast diversification is the family Ellisellidae, a major component of the mesophotic gorgonian coral assemblage worldwide. Full article

(This article belongs to the Special Issue Biodiversity of Mesophotic Ecosystems)

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6 pages, 2261 KiB

Open AccessEditor’s ChoiceInteresting Images

Unexplored Refugia with High Cover of Scleractinian Leptoseris spp. and Hydrocorals Stylaster flabelliformis at Lower Mesophotic Depths (75–100 m) on Lava Flows at Reunion Island (Southwestern Indian Ocean)

by Ludovic Hoarau, Héloïse Rouzé, Émilie Boissin, Nicole Gravier-Bonnet, Patrick Plantard, Camille Loisil, Lionel Bigot, Pascale Chabanet, Priscille Labarrère, Lucie Penin, Mehdi Adjeroud and Thierry Mulochau

Diversity 2021, 13(4), 141; https://doi.org/10.3390/d13040141 - 25 Mar 2021

Cited by 10 | Viewed by 7051

Abstract

Despite increased attention over the last decade on Mesophotic Coral Ecosystems (MCEs) [...] Full article

(This article belongs to the Special Issue Biodiversity of Mesophotic Ecosystems)

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