Search

Zooplankton plays a pivotal role in sustaining the majority of marine ecosystems. The distribution patterns and diversity of zooplankton provide key information for understanding the functioning of these ecosystems. Nevertheless, due to the numerous cryptic and sibling species and the lack of diagnostic characteristics for early developmental stages, the identification of the global-to-local patterns of zooplankton biodiversity and biogeography remains challenging in different research fields. The spatial and temporal changes in the zooplankton community in the open waters of the southern Gulf of Mexico were assessed using metabarcoding analysis of the V9 region of 18S rRNA and mitochondrial cytochrome oxidase c subunit I (COI). Additionally, a multiscale analysis was implemented to evaluate which environmental predictors may explain the variability in the structure of the zooplankton community. Our findings suggest that the synergistic effects of dissolved oxygen concentration, temperature, and longitude (intended as a proxy for still unidentified predictors) may explain both spatial and temporal zooplankton variability even with low contribution. Furthermore, the zooplankton distribution probably reflects the coexistence of three heterogeneous ecoregions and a bio-physical partitioning of the studied area. Finally, some taxa were either exclusive or predominant with either 18S or COI markers. This may suggest that comprehensive assessments of the zooplankton community may be more accurately met by the use of multilocus approaches.

Zooplankton is a key component in marine ecosystem health assessment. Here, we present a taxonomically comprehensive description of the zooplankton community (0–200 m) based on metabarcoding of the V9 hypervariable region of the 18S rRNA gene of 47 samples collected in the Gulf of Mexico (GoM) during summer 2015. Fourteen phyla were identified Arthropoda were dominant, with Calanidae, Metridinidae, and Euphausiidae as the most conspicuous families. Other abundant phyla were Cnidaria (Hydrozoa), Chordata (Tunicata), and Chaetognatha. The V9-18S sequence data were clustered into 1888 Operational Taxonomic Units (OTUs), of which 39 were cosmopolitan and belonging to various phyla, suggesting the presence of a core community with high local diversity throughout the GoM. Evaluation of metabarcoding sequences abundance showed overall positive correlations with morphologically quantified abundances except for specific groups. Cluster analysis of OTU distributions indicated two primary biographically distinctive groups of stations: one restricted to the Bay of Campeche, while the other occurred in the Central-West GoM, similar to previous descriptions of regional variation of the GoM based on environmental variables. Together these results provide a foundation for broad-scale zooplankton molecular biodiversity assessments in the southern GoM allowing evaluation of the effects of environmental changes on zooplankton communities.

Zooplankton play a pivotal role in sustaining the majority of marine ecosystems. The distribution patterns and diversity of zooplankton provide key information for understanding the functioning of these ecosystems. Nevertheless, due to the numerous cryptic and sibling species and the lack of diagnostic characteristics for immature developmental stages, the identification of the global-to-local patterns of zooplankton biodiversity and biogeography remains a challenge in different research fields. Here, the spatial and temporal changes in the zooplankton community from the open waters of the southern section of the Gulf of Mexico were assessed using a multilocus sequence analysis and metabarcoding approach based on the genetic information of 18S and cytochrome oxidase c subunit I (COI) genes. Additionally, a multi-scale analysis was implemented to evaluate which environmental predictors may explain the variability in the structure of the zooplankton community. Our finding suggests that the synergistic effects of oxygen, temperature, and longitude (intended as a proxy for still unexplored forces) may explain both spatial and temporal changes in the zooplankton community. Furthermore, the zooplankton distribution likely reflects the coexistence of three heterogeneous ecoregions and a bio-physical partitioning of the studied area. Finally, some taxa were either exclusive or predominant with either 18S or COI data. This may suggest that comprehensive assessments of the zooplankton community may be more accurately met by the use of multi-locus approaches.

Accurate identification of fish larval stages is complicated and time-consuming due to the lack of diagnostic morphological characters, especially during early developmental stages. The distribution of lanternfish (Myctophidae) has been described based on the morphological identification of adult stages. Larvae of only a few species of Myctophidae have been described, and the description is not always precise. In this study, larvae were collected and morphologically identified as Diaphus mollis, Hygophum hygomii, H. reinhardtii, H. taaningi, Myctophum obtusirostre and M. selenops. The DNA barcode region of the mitochondrial cytochrome oxidase I gene (COI) was determined for all larvae. The COI sequences matched reference barcodes available in GenBank for 14 of the identified larvae. The remaining COI sequences matched reference barcodes for different species of Myctophidae including Centrobranchus nigroocellatus, Diogenichthys atlanticus and Lepidophanes guentheri. This effort demonstrated the importance of integrated morphological and molecular analysis of species diversity and distribution of the Myctophidae in the Gulf of México.