Megabenthic communities distributed in the outer margins of the Yucatan shelf and their relationship to environmental variables

ABSTRACT

Megabenthic communities on continental margins benefit from structural complexity of the seafloor and sedimentary dynamics. These communities were tested in the outer margins of the Yucatan continental shelf (YCS) during August 2016 to evaluate the relationships between community attributes with environmental variables. The total capture was 1,366 10³ ind km⁻² and 2,078 kg ash free dry weight (AFDW) km⁻², distributed among 319 species. Crustaceans and molluscs were co-dominant in abundance (576,629 ind km⁻² ∼42.2% and 481,372 ind km⁻² ∼35.2%), while crustaceans and sponges were the greatest contributors to community biomass (699.84 kg AFDW km⁻² ∼33.6% and 47.8 kg AFDW km⁻² ∼23.0%). Local diversity was higher than reported for other areas of the GoM, showing a pseudo-latitudinal gradient of richness related to the karstic bottom and autogenic species. Beta diversity showed no species loss in these communities. The BIOENV test pointed to longitude, temperature, sorting, vanadium, 2.6-dimethyl naphthalene, latitude, chlorophyll, average grain size, n-C₁₆ and n-C₂₃ as the most important variables. Hydrocarbons were recorded at lower concentrations than the threshold effects level (TEL) reference values; however, the significant correlation between richness and dibenzothiophene must be evaluated. Beta diversity exhibited a high turnover and functional diversity showed an absence of regional distribution. Differences in benthic megafauna among sites were because of gradients in latitude and concentrations of aliphatic compounds which can be attributed to the distance from the stations to the coastline or groundwater flow. Environmental monitoring programmes are recommended because of petrogenic compounds that influence the community structure.

KEYWORDS:

• Alpha diversity
• benthic megafauna
• benthic biomass
• continental shelves
• marine ecology
• sediments
• turnover

Acknowledgements

This research was funded by the Mexican National Council for Science and Technology -Mexican Ministry of Energy- Hydrocarbon Fund, project 201441. This research is a contribution of the Gulf of Mexico Research Consortium (CIGoM). We acknowledge PEMEX's specific request to the Hydrocarbon Fund to address the environmental effects of oil spills in the Gulf of Mexico. The authors are grateful for the logistical support provided by members of the Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Merida (CINVESTAV-Merida), during collection on the GOMEX V oceanographic cruise. Special thanks to the members of the Immunology and Molecular Biology, Primary Production, Marine Geochemistry, and Coastal Processes and Physical Oceanography laboratories of CINVESTAV-Merida for their help and participation during sample collections, for laboratory work and data management. Rubio-Polania also thanks Elohan Shamayyim for the support and help in different aspects of the PhD, also to Nadia Siordia, Igor Granado Domínguez and Oscar Ortegon for their help with some processes of this project. The authors thank all comments provided by the reviewers that improved the quality of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was funded by the Mexican National Council for Science and Technology -Mexican Ministry of Energy- Hydrocarbon Fund, project 201441.