José Rolando Bastida-Zavala

Neomicrorbis Rovereto, 1903 is a serpulid taxon well represented in the Cretaceous and Tertiary fossil records and described as the bathyal extant species Neomicrorbis azoricus Zibrowius, 1972. This enigmatic species of uncertain taxonomic affinities exhibits a morphology intermediate between serpulids sensu stricto (Serpulinae and Filograninae) and Spirorbinae. Only recently the phylogenetic placement of these unique serpulids has been clarified, unequivocally positioning them as the sister group to all other Spirorbinae. Despite this advancement, most aspects of their biology, distribution, and even morphology remain largely unexplored. We provide detailed morphological descriptions of specimens from the Azores (type locality) in the Atlantic, as well as from the Indian and the Pacific Oceans, using both long-hidden material in museum collections and recently collected specimens. This study enhances the original description of N. azoricus, which was based on a single, poorly preserved juvenile specimen, by offering a comprehensive overview of the species’ morphology. Our analysis utilizes advanced imaging techniques such as scanning electron microscopy, microCT, and 3D visualization. Contrast-enhanced microCT scanning has proven exceptionally valuable for non-invasive visualization of the worms within their calcareous tubes. This method shows great promise for studying serpulids in natural history collections. Our findings reveal a remarkable morphological consistency across specimens from geographically remote regions, suggesting a wide distribution for the species. However, molecular data on Neomicrorbis are currently limited to recently collected specimens from the Indian Ocean. Further genetic studies are necessary to fully understand the population structure and genetic diversity of Neomicrorbis azoricus across its range.

The mesophotic zone represents one of our planet’s largest and least explored biomes. An increasing number of studies evidence the importance of macrofouling species in marine ecosystems, but information on these communities and the factors influencing their structures at mesophotic depths remain poor. This lack of understanding limits our ability to predict anthropogenic impacts or conduct restoration operations in the mesophotic and the lower boundary of the euphotic zones. In this study, we performed a 24-month experiment in a natural environment to investigate three factors influencing the macrobenthic community structure of the mesophotic and the euphotic lower boundary: depth, substrate orientation and substrate material. Using a manned submersible, several recruitment panels of two different materials were deployed at 100, 200 and 400 meters in vertical and horizontal positions. All three factors contributed to structuring the macrofouling communities, but depth and substrate orientation displayed the strongest effects. This study not only advances our understanding of lower boundary euphotic and mesophotic macrofouling communities but also establishes a foundation for future research and restoration efforts of mesophotic environments in the Madeira archipelago, where mesophotic habitats are amongst the least studied marine habitats in the Northeast Atlantic.

The port fouling fauna from Mexico has recieved greater study in the last 15 years. By improving our knowledge of fouling invertebrates on artificial substrates on the Southern Pacific coast of Mexico, we can better understand their distribution and prevent bioinvasions. The specimens listed in this present study come from PVC plates that were placed between June 2019 to June 2020 submerged at 1 m depth, on four docks of the Chahué Marina, Oaxaca, Mexico. Forty-four taxa, representing nine phyla were identi-fied: Sipuncula (1 species), Entoprocta (1), Bryozoa (3), Arthropoda (3), Porifera (4), Cnidaria (5), Chordata (6), Mollusca (10) and Annelida (11). Thirty taxa were identified to species, with two still requiring confirmation. Five were identified to genus, two to family, and five to class level. From the 30 identified species, 18 were non-native species: one entoproct, one mollusk, two bryozoans, three hydrozoans, three barnacles, four polychaetes, and four ascidians. These results include seven new records from the state of Oaxaca: one entoproct, one barnacle, two bryozoans, and three hydrozoans.

A small colony of the snowflake coral, Carijoa riisei, was collected from Corralero Lagoon in June 2015. This species is native to the Indo-West Pacific and, as invasive species, spread into Tropical Western Atlantic, Hawaii, Western Africa and Tropical Eastern Pacific. This record suggests that the invasion of C. riisei in the Mexican Pacific could be earlier than inferred and by means other than biofou-ling or ballast water, as Corralero Lagoon at least 190 km away from any port. Monitoring is recommended in the reefs, coastal lagoons, ports and marinas of the Mexican Pacific to evaluate the dispersion of this inva-sive species, in addition to proposing mitigation and management measures.

Environmental temperature is one of the most significant factors influencing the developmental rate and survival of embryos and larvae of many marine animals, including polychaetes. The aim of this study was to experimentally evaluate the effect of temperature increase on the embryonic development and larval survival of Spirobranchus incrassatus and S. cf. corniculatus. Adult worms of both species were collected from the western margin of the Gulf of Tehuantepec, Mexico. Embryos and larvae were obtained from these worms and exposed to four temperature treatments (28, 30, 32 and 34°C). The optimal temperature for embryonic development of S. incrassatus and S. cf. corniculatus was 30 and 28°C, respectively. For both species, the maximum critical temperature was 32°C and the lethal temperature was 34°C. The embryonic stages of S. cf. corniculatus were most negatively affected by elevated temperatures. Larval survivorship of S. incrassatus and S. cf. corniculatus was higher at 30°C and 28°C (76.2±2.8%; 72.6±4.2%) and lower at 34°C (28.9±2.6%; 26.3±2.9%), respectively. These results suggest that S. cf. corniculatus has the lowest thermal tolerance. Both Spirobranchus species already live near their upper limit of thermal tolerance in the study region (30°C). In the near future, under a global warming scenario, the distribution of both species could be modified, causing a loss of biodiversity, changes in the trophic chain, and alterations in the water column, such as excess organic matter.

Early naturalists suggested that predation intensity increases toward the tropics, affecting fundamental ecological and evolutionary processes by latitude, but empirical support is still limited. Several studies have measured consumption rates across latitude at large scales, with variable results. Moreover, how predation affects prey community composition at such geographic scales remains unknown. Using standardized experiments that spanned 115° of latitude, at 36 nearshore sites along both coasts of the Americas, we found that marine predators have both higher consumption rates and consistently stronger impacts on biomass and species composition of marine invertebrate communities in warmer tropical waters, likely owing to fish predators. Our results provide robust support for a temperature-dependent gradient in interaction strength and have potential implications for how marine ecosystems will respond to ocean warming.

Species of the genus Spirobranchus are sessile polychaetes with an important role in marine ecosystems since they are suspension-feeding invertebrates. However, for most species almost nothing is known about their early and larval development, so we describe the early development of two species of Spirobranchus from the Southern Mexican Pacific. The early trochophore larva of S. incrassatus was formed 12 h post-fertilization at 28°C and was described up to a 24-day-old metamorph, whilst it was only possible to follow S. cf. corniculatus to the eight-day-old early trochophore larva. With this study, we describe the early embryological stages, which provide an understanding of the reproductive biology of these polychaetes. Furthermore, this type of information is the basis for future experimental work on the possible response of embryos and larvae to changes in environmental variables, such as temperature.