Distribution of planktonic cnidarian assemblages in the southern Gulf of Mexico, during autumn

Abstract

Background: Despite their ecological, economic and medical relevance, very little information is available on the distribution of planktonic cnidarians, this being particularly true for some regions of the ocean such as the Gulf of Mexico. In fact, the effect of locally important oceanographic features such as the offshore autumnal transport on the distribution of planktonic cnidarians has long been overlooked in this region. Because of this, the present study aimed to analyse the spatial patterns of planktonic cnidarian assemblages in the southern Gulf of Mexico during the autumn of 1998, when particularly intense conditions of convergence, offshore water transportation and productivity were recorded. The assemblages were described in terms of their composition, abundance (volume), diversity, dominance and equitability. Cluster (Bray-Curtis index) and ordination (multidimensional scaling (MDS)) analysis were performed in order to link the observed distribution of species with the environmental parameters.

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“…Aunque el estudio formal del plancton en aguas mexicanas inició hace más de medio siglo, la mayoría de los estudios realizados corresponden principalmente a investigaciones en aguas epicontinentales y marinas, con referencia a la sistemática y distribución solo de algunos grupos del zooplancton (Suárez-Caabro & Gómez-Aguirre, 1965;Suárez-Morales, 2003), principalmente sobre cnidarios (Martell-Hernández et al, 2014;Mendoza-Becerril et al, 2009;Ocaña-Luna et al, 2015), copépodos (López-Salgado & Suarez- Morales, 1998;López-Salgado et al, 2000;Suárez-Morales & Gasca, 1998), e ictioplancton (Flores-Coto et al, 2009;Ocaña-Luna & Sánchez-Ramírez, 2016;Sanvicente-Añorve et al, 2000).…”

“…El zooplancton gelatinoso incluyó dos especies de medusas, una de ctenóforo y un género de hidromedusa (Obelia sp. ), del cual no fue posible determinar taxonómicamente la especie, debido a que los caracteres de identificación a este nivel están basados en el pólipo y no en el estado de medusa (Martell-Hernández et al, 2014). Los poliquetos también incluyeron cuatro especies, mientras que un quetognato y un branquiuro completaron el elenco sistemático.…”

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“…Remarks. The two most common species from the genus Corymorpha in the Gulf of Mexico are C. nutans and C. gracilis (Brooks, 1883) (Martell- Hernández et al, 2014;Pruski & Miglietta, 2019). The main differences among these species are the length of the apical projection and the marginal bulbs.…”

“…On the other hand, its distribution in the water column is limited and depends on the patterns of marine currents. Thus, they can be used as indicators of water masses and their movements (Martell-Hernández et al, 2014). Like other members of gelatinous zooplankton, their massive proliferation, together with its predatory features makes of them top predators, which can generate an imbalance in food chains (Boero et al, 2008).…”

Zooplankton summer composition in the southern Gulf of Mexico with emphasis on salp and hyperiid amphipod assemblages

“…The zooplankton assemblage of the deep basins of the GOM is dominated in both abundance and biomass by calanoid copepods followed by euphausiids and chaetognaths (Hopkins, 1982; Suárez-Morales et al ., 2009; Rowe, 2017). However, some low-abundance taxa, such as cnidarians and pelagic tunicates, bloom under favourable conditions and may occasionally dominate the zooplankton (Esnal, 1979; Suarez-Morales et al ., 2002; Flores-Coto et al ., 2010; Sanvicente-Añorve et al ., 2013; Martell-Hernández et al ., 2014; Färber Lorda et al ., 2019). These blooms are frequently associated with the occurrence of other diverse taxa (Schabetsberger et al ., 2003; Gasca et al ., 2009).…”