Abundance and diversity patterns and environmental drivers of Peracarida (Arthropoda, Crustacea) macrofauna from the deep sea of the southwestern Gulf of Mexico

Abstract

We present unique data of abundance, spatial diversity, and bathymetric patterns of the Peracarida communities of the economic and ecological important scarce studied area of the southern Gulf of Mexico. Peracarida macrofauna was collected from 63 sites in a large geographical area (92.67°– 96.70° W, 18.74°–23.04° N) with a wide bathymetric gradient (185–3740 m depth) of the deep-sea southwestern Gulf of Mexico. The samples were obtained onboard the R/V Justo Sierra (Universidad Nacional Autónoma de México, UNAM) using a Reineck-type box corer during four oceanographic cruises (SOGOM 1–4; 2015–2018). We examined the bathymetric and spatial patterns of standardized abundance (ind. m^-2) and taxonomic diversity (Hill numbers, q = 0, 1, and 2). Abundance patterns were related to environmental parameters (organic matter, aromatic and aliphatic hydrocarbons, bottom water temperature, dissolved oxygen and grain composition). We collected 684 specimens belonging to 53 Peracarida families of 4 orders (Amphipoda, 19; Isopoda, 17; Tanaidacea, 13; and Cumacea, 4). The most abundant orders were Amphipoda and Tanaidacea, representing 36.4% and 35.8% of the total abundance, respectively, followed by Isopoda (25.1%). Cumacea was the least abundant order (2.7%). The top ten abundant families in order were Apseudidae, Phoxocephalidae, Caprellidae, Desmosomatidae, Nototanaidae, Nannoniscidae, Tanaellidae, Ischnomesidae, Podoceridae, and Agathotanaidae, accounting for 66% of the total relative abundance. The abundance decreased with increasing depth. Highest values were recorded in the northwestern region of the study area and in the Campeche Bay salt domes zone, whereas the lowest abundance values were registered at the abyssal locations and in some sites located in the Coatzacoalcos and Campeche Canyons. The composition and structure of the peracarid community showed shifts related to depth. The major structural abiotic factors of the Peracarida community were: latitude, depth, temperature, and sediment aliphatic hydrocarbons. The diversity based on the three estimated Hill numbers consistently decreased with increasing depth. We recorded intermediate and low diversity values in almost the entire study area, except for the Campeche Bay salt domes zone and northwestern region, where intermediate and high diversity values were registered.