Exposure to contaminants might directly affect organisms and alter their associated microbiota. The objective of the present study was to determine the impact of the petroleum-water-accommodated fraction (WAF) from a light crude oil (API gravity 35) on a benthic fish species native from the Gulf of Mexico (GoM). Ten adults of Achirus lineatus (Linnaeus, 1758) were exposed to a sublethal WAF/water solution of 50% v/v for 48 hr. Multiple endpoints were measured including tissue damage, presence of polycyclic aromatic hydrocarbons (PAHs) metabolites in bile and gut microbiota analyses. Atrophy and fatty degeneration were observed in livers. Nodules and inflammation were detected in spleen, and structural disintegration and atrophy in the kidney. In gills hyperplasia, aneurysm, and gills lamellar fusion were observed. PAHs metabolites concentrations in bile were significantly higher in exposed organisms. Gut microbiome taxonomic analysis showed significant shifts in bacterial structure and composition following WAF exposure. Data indicate that exposure to WAF produced toxic effects in adults of A. lineatus, as evidenced by histological alterations and dysbiosis, which might represent an impairment to long-term subsistence of exposed aquatic organisms.

Panulirus argus virus 1 (PaV1), a pathogenic virus that specifically attacks Caribbean spiny lobsters Panulirus argus, was recently detected in newly settled postlarvae of P. argus. As PaV1 appears not to be vertically transmitted, infected postlarvae likely acquire PaV1 from the water, but whether this can occur in oceanic waters where the planktonic larvae (phyllosomata) metamorphose into nektonic postlarvae remains unknown. Late-stage phyllosomata and postlarvae of P. argus were collected at distances of 2 to 100 km from the Caribbean coast of Mexico in 2 oceanographic cruises. Most postlarvae were caught in the upper meter of water, usually along with masses of floating Sargassum algae. A PaV1-PCR assay was used to test 169 phyllosomata (stages VI-X) and 239 postlarvae. All phyllosomata tested negative, but 2 postlarvae, 1 from each cruise, tested positive for PaV1. These postlarvae were collected at 55 and 48 km offshore over depths of 850 and 1800 m, respectively, suggesting that postlarvae can acquire PaV1 in offshore waters. We hypothesize that floating Sargassum may be an environmental reservoir for PaV1. The PaV1 allele (460 pb) found in an infected postlarva was more closely related to PaV1 alleles found in lobsters from Puerto Rico than in lobsters from any other location (including Mexico), suggesting high gene flow and long-distance dispersal of PaV1, consistent with previous studies of high genetic connectivity across the Caribbean.

Paralarvae (PL) are crucial to understanding the life cycle and population dynamics of cephalopods. Misidentification of species with similar morphology is a problem that hampers understanding of cephalopod composition and distribution. In this study, we used morphological and molecular approaches to carry out a comprehensive identification of Octopoda PL that inhabit two main areas (Tamaulipas and Yucatán) in the southern Gulf of Mexico (GoM). A total of 189 PL were identified using morphological criteria. Of these, 52 PL were analyzed molecularly by sequencing the mitochondrial cytochrome c oxidase subunit I (COI) gene. We identified four species and five morphotypes. The molecular tools corroborated three out of four species, while the molecular sequences of three out of four morphotypes indicated that they belong to three different species. All the genetic sequences had high similarities (99.3%–100%) with previous records. One species and one morphotype could not be sequenced because of unsatisfactory fixation; one morphotype remained as such after the molecular analysis. An identification tree was constructed for the species identified with the molecular approach. The species found off the Yucatán platform were Octopus vulgaris Type I, Octopus americanus, Macrotritopus defilippi, Amphioctopus burryi, A. cf. burryi, Octopus sp., and Callistoctopus furvu s. The species identified off the Tamaulipas coast were Octopus insularis and M. defilippi. Paralarvae of O. vulgaris Type I and M. defilippi were the most abundant during 2016–2017. This study provides the first record of Octopoda PL in the southern GoM, including morphological descriptions and molecular sequences of the analyzed taxa.