RESUMO
Coral reefs are losing the capacity to sustain their biological functions1. In addition to other well-known stressors, such as climatic change and overfishing1, plastic pollution is an emerging threat to coral reefs, spreading throughout reef food webs2, and increasing disease transmission and structural damage to reef organisms3. Although recognized as a global concern4, the distribution and quantity of plastics trapped in the world's coral reefs remains uncertain3. Here we survey 84 shallow and deep coral ecosystems at 25 locations across the Pacific, Atlantic and Indian ocean basins for anthropogenic macrodebris (pollution by human-generated objects larger than 5 centimetres, including plastics), performing 1,231 transects. Our results show anthropogenic debris in 77 out of the 84 reefs surveyed, including in some of Earth's most remote and near-pristine reefs, such as in uninhabited central Pacific atolls. Macroplastics represent 88% of the anthropogenic debris, and, like other debris types, peak in deeper reefs (mesophotic zones at 30-150 metres depth), with fishing activities as the main source of plastics in most areas. These findings contrast with the global pattern observed in other nearshore marine ecosystems, where macroplastic densities decrease with depth and are dominated by consumer items5. As the world moves towards a global treaty to tackle plastic pollution6, understanding its distribution and drivers provides key information to help to design the strategies needed to address this ubiquitous threat.
Assuntos
Recifes de Corais , Plásticos , Plásticos/efeitos adversos , Plásticos/análise , Cadeia Alimentar , Oceano Pacífico , Oceano Atlântico , Oceano Índico , Tamanho da Partícula , Atividades Humanas , CaçaRESUMO
A new labrid fish, Terelabrus toretore sp. nov., the fifth species within the genus, is herein described from two specimens collected at a depth of 140 m from a mesophotic coral ecosystem in Tahiti, French Polynesia. Terelabrus toretore sp. nov. is characterized by having 43-44 scaled rows in longitudinal series; 42 pored lateral-line scales; 5+10 gill rakers; 10 scale rows below the lateral line; 8 posterior branches on the main supratemporal sensory canal; a relatively long snout (snout length 9.6-9.7% SL), and a coloration consisting of a yellow caudal fin and a wide, red, mid-lateral stripe with no blotching, the space above which is white anteriorly, becoming predominantly yellow from beneath the dorsal fin to the caudal peduncle. In addition to describing this new species, we document the first record of Terelabrus rubrovittatus from the Republic of Marshall Islands, and the first record of Terelabrus zonalis from Australia, along with the first description of its coloration. We present a molecular phylogeny of the genus based upon mitochondrial cytochrome c oxidase subunit I (COI) DNA sequences.
RESUMO
Coral reefs are home to some of the most studied ecological assemblages on the planet. However, differences in large-scale assembly rules have never been studied using empirical quantitative data stratified along the depth gradient of reefs. Consequently, little is known about the small- and regional-scale effects of depth on coral reef assemblages. Using a large dataset of underwater surveys, we observed that the influence of classic biogeographic drivers on the species richness of coral reef fishes changes significantly with depth, shaping distinct assemblages governed by different rules in mesophotic coral ecosystems. We show that a general pattern of decreased taxonomic and functional richness of reef fish assemblages with depth results from convergent filtering of species composition and trophic strategies on deeper reefs across ocean basins and that at smaller scales deep-reef communities are less influenced by regional factors than shallower reefs.
Assuntos
Antozoários , Recifes de Corais , Animais , Ecossistema , Peixes , BiodiversidadeRESUMO
Pseudanthiashangapiko sp. nov. (Teleostei, Serranidae, Anthiadinae) is herein described from three specimens collected from a depth of 83 m in a mesophotic coral ecosystem off Hanga Piko, Rapa Nui (Easter Island), Chile. Pseudanthiashangapiko sp. nov. can be distinguished from its congeners in live coloration and by the following combination of characters: dorsal-fin rays X, 17; anal-fin rays III, 8; pectoral-fin rays 16 (left side of one specimen 17); vertebrae 10+16; scales relatively large, two scales above lateral-line to base of fifth dorsal spine, and 16-17 circumpeduncular scales; gill rakers 11+23; and a slender body, with greatest body depth 3.6 (3.4-3.8) in SL. The most similar DNA barcodes (mitochondrial COI gene) are from Pseudanthiasventralis Randall, 1979 and Pseudanthiashawaiiensis Randall, 1979, with 16.8% and 17.0% uncorrected divergence, respectively. This fish is one of four new species that were documented from a pair of technical dives at a single location in Rapa Nui, emphasizing the high number of undescribed species likely still unknown in mesophotic coral ecosystems, especially in geographically remote locations. Pseudanthiashangapiko sp. nov. adds to the Rapa Nui ichthyofauna, which hosts the second-highest level of endemism in both shallow and deep-water fishes.
RESUMO
Understanding interactions between spatial gradients in disturbances, species distributions and species' resilience mechanisms is critical to identifying processes that mediate environmental change. On coral reefs, a global expansion of coral bleaching is likely to drive spatiotemporal pulses in resource quality for obligate coral associates. Using technical diving and statistical modelling we evaluated how depth gradients in coral distribution, coral bleaching, and competitor density interact with the quality, preference and use of coral resources by corallivore fishes immediately following a warm-water anomaly. Bleaching responses varied among coral genera and depths but attenuated substantially between 3 and 47 m for key prey genera (Acropora and Pocillopora). While total coral cover declined with depth, the cover of pigmented corals increased slightly. The abundances of three focal obligate-corallivore butterflyfish species also decreased with depth and were not related to spatial patterns in coral bleaching. Overall, all species selectively foraged on pigmented corals. However, the most abundant species avoided feeding on bleached corals more successfully in deeper waters, where bleaching prevalence and conspecific densities were lower. These results suggest that, as coral bleaching increases, energy trade-offs related to distributions and resource acquisition will vary with depth for some coral-associated species.
Assuntos
Antozoários/fisiologia , Ecossistema , Comportamento Alimentar , Peixes/fisiologia , Temperatura , Água , Animais , Branqueamento de CoraisRESUMO
Two new species of Plectranthias perchlets are described, collected from mesophotic coral ecosystems in French Polynesia and the Republic of the Marshall Islands, in the tropical Central Pacific. Plectranthias polygonius sp. nov. was collected at a depth of 105 m in Tahiti, French Polynesia, and 120 m in Maloelap Atoll, Republic of the Marshall Islands. It was also observed in Moorea and Rangiroa (French Polynesia), and at Majuro and Erikub Atolls, Republic of the Marshall Islands. Plectranthias hinano sp. nov. was collected at a depth of 90-98 m in Tahiti, French Polynesia, and observed in Moorea. The barcode fragment of the cytochrome oxidase I gene of Plectranthias polygonius sp. nov. does not closely match any published sequence of Plectranthias, with approximately 15% uncorrected divergence from several species. Plectranthias polygonius sp. nov. can be distinguished from all of its congeners by coloration and morphology. The barcode fragment of the COI gene of Plectranthias hinano sp. nov. is closest to Plectranthias bennetti, with 5.4% uncorrected divergence. Plectranthias hinano sp. nov. is also distinguished from all of its congeners by morphology, and a coloration that includes two indistinct black spots along the base of the dorsal-fin, and transparent yellow dorsal and anal fin membranes. With this publication, the genus Plectranthias now comprises 58 valid species, with representatives from tropical to temperate waters of the Atlantic, Pacific, and Indian oceans. These two new discoveries add to the growing body of research highlighting the rich biodiversity of mesophotic ecosystems.
RESUMO
Abstract Although several studies on the ichthyofauna of the Fernando de Noronha Archipelago have been carried out, its mesophotic fish diversity has never been surveyed before. Here we used SCUBA and technical rebreather diving, baited remote underwater videos and remotely operated vehicle to record shallow (≤ 30 m depth) and mesophotic (31 to 150 m depth) fishes. Nineteen fish species belonging to 14 families are reported here as new records, representing an increase of 8.2% in marine fish richness for the region, which now has a total of 250 species and 77 families. These new records include four potential new species and highlight the importance of surveying mesophotic ecosystems, even in well studied sites. Our results also emphasize the need for protection and attention to the unique ichthyofauna found at mesophotic depths.(AU)
Resumo Apesar de muitos estudos sobre a ictiofauna do Arquipélago de Fernando de Noronha terem sido realizados, sua diversidade de peixes mesofóticos nunca foi estudada antes. Neste estudo utilizamos mergulho autônomo e mergulho técnico, vídeos subaquáticos remotos com isca e veículo operado remotamente para registrar peixes de ecossistemas rasos (≤ 30 m de profundidade) e mesofóticos (31 a 150 m de profundidade). Dezenove espécies de peixes pertencentes a 14 famílias são apresentadas aqui como novos registros, representando um aumento de 8,2% na riqueza de peixes marinhos da região, que agora possui um total de 250 espécies e 77 famílias. Esses novos registros incluem quatro prováveis novas espécies e reforçam a importância de estudos em ecossistemas mesofóticos. Nossos resultados também enfatizam a necessidade de proteção e atenção à essa ictiofauna única encontrada nesses ecossistemas profundos.(AU)