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Abstract Introduction: The scleractinian coral life cycle includes planktonic larvae that settle on the benthos, allowing the primary polyp to clone and build a sexually reproducing adult colony. The larval physiology and ecology of Eastern Tropical Pacific scleractinians needs the exploration of basic aspects such as the internal morphology of planulae. Objective: To describe histological and cytological characteristics of Porites panamensis larvae. Methods: During August-July 2019, at Islas Marias Biosphere Reserve, Central Mexican Pacific, we made 14 collections of coral larvae and identified the species with cytochrome oxidase subunit 1 gene. We used a scanning electron microscope and other techniques. Results: The ectoderm was composed by heterogeneous, mono-ciliated, columnar epithelial cells. Nematocysts were clustered at the oral pole of the ectoderm, and cells were evident in the aboral pole of the ectoderm gland. The endoderm had secretory cells, lipids and symbionts. Conclusions: The abundance of secretory cells and nematocysts in the aboral pole suggests their importance in substrate exploration and larval settlement. Our results support previous descriptions of larval ultrastructure in other coral species.
Resumen Introducción: El ciclo de vida del coral escleractinio incluye larvas planctónicas que se asientan en el bentos, lo que permite que el pólipo primario se clone y construya una colonia de adultos con reproducción sexual. La fisiología y ecología larvaria de los escleractinios del Pacífico Tropical Oriental necesita la exploración de aspectos básicos como la morfología interna de las plánulas. Objetivo: Describir las características histológicas y citológicas de las larvas de Porites panamensis. Métodos: Durante agosto-julio 2019, en la Reserva de la Biosfera Islas Marías, Pacífico Central Mexicano, realizamos 14 recolectas de larvas de coral e identificamos las especies con el gen citocromo oxidasa subunidad 1. Utilizamos un microscopio electrónico de barrido y otras técnicas. Resultados: El ectodermo está compuesto por células epiteliales columnares heterogéneas, monociliadas. Los nematocistos se agrupan en el polo oral del ectodermo, mientras que en el polo aboral son visibles células glandulares. El endodermo presentó células secretoras, lípidos y simbiontes. Conclusiones: La abundancia de células secretoras y nematocistos en el polo aboral sugiere su importancia en la exploración del sustrato y asentamiento larvario. Nuestros resultados respaldan las descripciones previas de la ultraestructura de las larvas en otras especies de coral.
Assuntos
Plâncton/ultraestrutura , MéxicoRESUMO
The complete mitogenome of Thoosa mismalolli Carballo, Cruz-Barraza & Gómez, 2004 (Tetractinellida, Thoosidae) was sequenced. This is the first complete mitogenome of the suborden Thoosina and the third Tetractinellid so far. The mitochondrial genome of T. mismalolli was assembled based on reads obtained with the Illumina HiSeq platform. The length of complete mitogenome is 19,019 bp long and contained 14 protein-coding genes and 23 tRNA, with two tRNA genes. Phylogenetic reconstruction (maximum-likelihood) based on mitogenome of Tetractinellids, supports T. mismalolli as a sister group. This result is congruent with those obtained with molecular markers (CO1, 18S, and 28S), supporting the monophyletic status of Thoosa and providing additional molecular data in favor of the suborder Thoosina.
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Coral reef ecosystems are continuously degraded by anthropogenic and climate change drivers, causing a widespread decline in reef biodiversity and associated goods and services. In response, active restoration methodologies and practices have been developed globally to compensate for losses due to reef degradation. Yet, most activities employ the gardening concept that uses coral nurseries, and are centered in easily-accessible reefs, with existing infrastructure, and impractical for coral reefs in remote locations. Here we evaluate the effectiveness of direct outplanting of coral micro-fragments (Pavona clavus and Pocillopora spp.) as a novel approach to restore remote reefs in the Islas Marías archipelago in the Eastern Tropical Pacific. Coral growth (height-width-tissue cover), survival percentage, extension rates (cm year-1), skeletal density (g cm-3) and calcification rates (g cm-2 year-1) were assessed over 13 months of restoration. In spite of detrimental effects of Hurricane Willa, transplants showed a greater-than-twofold increase in all growth metrics, with ~58-61% survival rate and fast self-attachment (within ~3.9 months) for studied species, with Pocilloporids exhibiting higher extension, skeletal density, and calcification rates than Pavona. While comprehensive long-term studies are required, direct transplantation methodologies of coral micro-fragments are emerging as time-effective and affordable restoration tools to mitigate anthropogenic and climate change impacts in remote and marginal reefs.
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Antozoários , Biodiversidade , Ecossistema , Animais , Mudança Climática , Recifes de CoraisRESUMO
Bacterial assemblages associated with the hermatypic corals Pocillopora damicornis and P. verrucosa, the surrounding seawater and the sediment at six coral reef sites in the north section of the Tropical Eastern Pacific were assessed using MiSeq Illumina sequencing of the V4 region of the 16S rDNA. The bacterial microbiota in both coral species, seawater and sediment were stable to seasonal variations. Bacterial assemblages between the same substrates were not significantly different from each other in the six sites sampled. Interestingly, the bacterial composition between substrates within the same site was significantly different, or not, depending on the conservation status of the site. Moreover, we found species-specific bacterial OTUs in both coral species. Analyzing the relationship between bacterial composition and environmental variables revealed a positive correlation between bacterial assemblages and dissolved oxygen, ammonium and silicate.