Segregated Distribution of <i>Liriope tetraphylla</i>, <i>Aglaura hemistoma</i> and <i>Nausithoe punctata</i> (Cnidaria) in the Southern Gulf of Mexico

Abstract

In order to study the segregated distribution of the three most abundant jellyfish species in the southern Gulf of Mexico, a total of 85 stations were sampled during an oceanographic cruise from 19 May to 18 June 2006. Trawling took place from surface to a maximum depth of 200 m, using a Bongo net with a 61 cm mouth diameter and 333 and 500 µm mesh sizes. Temperature and salinity were recorded. Samples were preserved in 4% formalin, neutralized with sodium borate, and changed to 70% ethylic alcohol after 24 hours for conservation. The jellyfish data were standardized to 100 m 3 of filtered water. A total of 10,610 jellyfish were collected from the 333 µm mesh size net, of which eight species represented 88.49% of the total density: Aglaura hemistoma, Liriope tetraphylla, Nausithoe punctata, Clytia hemisphaerica, Persa incolorata, Obelia spp., Clytia folleata and Eutima gracilis. The former three species are the subject of this study. The results obtained indicate that the high density areas of these three species have a segregated distribution. -A. hemistoma, 0.88; L. tetraphylla -N. punctata, 0.86 and A. hemistoma -N. punctata, 0.84. The spatial distribution of the high density areas of these species fits well with the three hydrodynamically different areas: A. hemistoma in Campeche Bank, L. tetraphylla on the Campeche and Tabasco shelves and N. punctata in Campeche Bay. This spatial distribution pattern corresponds to their main habitat and reproductive habits of the species, as well as the influence of the hydrodynamics that dominate each area. Segregation values (White's index) recorded between pairs of specie were very high: L. tetraphylla

Species composition and distribution of Medusae (Cnidaria: medusozoa) in the Algerian coast between 2°e and 7°e (SW Mediterranean Sea)

“…This species separation, which was especially recorded for more abundant and frequent species, is not specific to these pairs. This trend has also been observed between other medusa species, such as L. tetraphylla -Nausisthoe punctata and A. hemistoma -Nausisthoe punctata (Flores-Coto et al, 2016).…”

“…The spatial segregation between the species compositions was analysed as follows: the D index = 1/2 ∑|(N1i/ N1)-(N2i/N2)| (Fenaux, 1963, Flores-Coto et al, 2016, where N 1i and N 2i represent the number of individuals of species 1 and species 2, respectively, at station i and N 1 and N 2 are the total numbers of individuals of species 1 and species 2, respectively.…”

First record of the genus Staurocladia (Hydrozoa: Cladonematidae) in the Gulf of Mexico with the description of Staurocladia dzilamensis sp. nov., a new species of crawling hydromedusa

“…Studies on hydrozoans from the southern Gulf of Mexico have been scarce and dispersed throughout history (e.g., Segura-Puertas 1992;Segura-Puertas & Ordóñez-López 1994;Mendoza-Becerril et al 2018;Ahuatzin-Hernández et al 2020. These have focused mainly on describing ecological aspects of planktonic organisms (e.g., Segura-Puertas 1992;Segura-Puertas & Ordóñez-López 1994;Loman-Ramos et al 2007;Martell-Hernández et al 2014;Flores-Coto et al 2016;Puente-Tapia et al 2022), so the taxonomy and biodiversity of benthic groups, such as hydroids (i.e., De la Cruz-Francisco European Journal of Taxonomy 921: 251-275 (2024Mendoza-Becerril et al 2018) and some Hydromedusae (e.g., Cortés-Lacomba et al 2013;Ahuatzin-Hernández et al 2020López-Torres et al 2023) are poor. Currently, there are no type species described for the southern Gulf of Mexico, and Cladonema radiatum Dujardin, 1843 is the only member of the Cladonematidae family reported in the region (Ahuatzin-Hernández et al 2020.…”