The metazoan parasite communities of the shoal flounder (Syacium gunteri) as bioindicators of chemical contamination in the southern Gulf of Mexico

Abstract

BackgroundBecause agriculture and offshore oil extraction are significant economic activities in the southern Gulf of Mexico, high concentrations of nutrients and hydrocarbons are expected. As parasite communities are sensitive to environmental impacts, these contaminants should have an effect on metrics such as species richness, relative abundance and similarity. Consequently, these community metrics can be used as indicators of aquatic environmental health. Our objectives were to describe the parasite communities of the shoal flounder Syacium gunteri and to determine potential thresholds above which environmental contaminants become major controlling factors of parasite community metrics.MethodsThe study area included 33 sampling sites in the southern Gulf of Mexico, where benthic sediments, water and shoal flounder individuals were collected. Data on ecto- and endo-parasites from flounder and nutrients, contaminants and physicochemical variables from the water and sediments were obtained. The statistical associations of the parasite community metrics at the component and infracommunity levels and the environmental data were analysed using redundancy analysis (RDA).ResultsOverall, 203 shoal flounder were examined for parasites, recovering 13 metazoan parasite species, and 48 physicochemical (e.g. temperature, nutrients) and contaminant (e.g. hydrocarbons, heavy metals) variables were obtained. The larval stages of the cestode Oncomegas wageneri and the nematodes Pseudoterranova decipiens and Hysterothylacium sp. were numerically dominant at the component and infracommunity levels. The parasite community metrics had significant negative statistical associations with both nitrate and total PAHs. With the exception of these two chemicals, which exceeded the threshold effect levels (TELs), no other environmental variable exceeded the range considered safe for marine organisms.ConclusionsThe community metrics chosen generally had robust statistically significant associations with both physicochemical and contaminant variables, which supports the ecological relevance of these parameters as indicators of aquatic environmental health. Within the study area, the shoal flounder and their parasites live in a polluted environment with relatively high levels of hydrocarbons and nitrate. Regarding nitrate, we emphasise that if uncontrolled sewage discharge continues in the southern Gulf of Mexico, hypoxic conditions similar to those caused by the Mississippi river can be expected in the near future.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-014-0541-3) contains supplementary material, which is available to authorized users.

The metazoan parasite communities of the shoal flounder ( Syacium gunteri ) as bioindicators of chemical contamination in the southern Gulf of Mexico

“…The unexpected combined effect of alkalinity and pH upon the parasites is very suggestive, and we speculate that the potential interaction between pH and the decrease in the number of parasites cannot be disregarded. The community metrics chosen generally had robust statistically significant associations with both physicochemical and contaminant variables, which supports the ecological relevance of these parameters as indicators of aquatic environmental health [5,71].…”

Integrative taxonomy of Serrasentis gibsoni n. sp. (Acanthocephala: Isthmosacanthidae) from flatfishes in the Gulf of Mexico

“…Samples were obtained from March 2015 to June 2021. Oceanographic sampling procedures for the collection of fishes have been described elsewhere (i.e., Vidal-Martínez et al 2014, 2019; García-Teh et al 2022). Host dissection procedures followed Vidal-Martínez et al (2014, 2019) and García-Teh et al (2022).…”

“…have been reported from Micropogonias undulatus (Linnaeus, 1766) from Laguna Madre, Tamaulipas, Mexico (Iruegas-Buentello 1999). Particularly, recent studies of helminth communities from intestines of three flatfish species (Paralichthyidae) (i.e., Cyclopsetta chittendeni Bean, 1895; Syacium gunteri Ginsburg, 1933; and Syacium papillosum (Linnaeus, 1758)) from oceanic sites in the southern Gulf of Mexico (s-GoM) have reported S. sagittifer as the most prevalent adult acanthocephalan parasite species (Vidal-Martínez et al 2014, 2019; Centeno-Chalé et al 2015).…”

Polycyclic aromatic hydrocarbons in the cestode Oncomegas wageneri parasite of Mexican flounder Cyclopsetta chittendeni

“…All the parasites found of different taxa were counted in situ and divided into two groups. The first group, which included all the parasites (i.e., digeneans, nematodes, and acanthocephalans) except O. wageneri, was preserved in 70% alcohol and used for both molecular and morphological taxonomy (see Vidal-Martínez et al (2014) for details). In contrast, the second group, which included the O. wageneri larvae, was frozen at −20°C immediately after extraction from the fish without any solution.…”

“…Oncomegas wageneri is a larval cestode infecting flatfishes collected from oil extraction zones of the Mexican Gulf of Mexico (Vidal-Martínez et al 2014;Centeno-Chalé et al 2015;Vidal-Martínez et al 2015;Martínez-Aquino et al 2019). This parasite is a good candidate for the detection of PAH metabolites because it has a wide geographical distribution in the Gulf of Mexico, has a high prevalence and mean abundance in its host, and inhabits the intestine of the flatfishes where it can be exposed to whatever the host is ingesting (including food contaminated with PAH) (Vidal-Martínez et al 2014). Support for this suggestion comes from the findings of Oluoch-Otiego et al (2016), who have shown that intestinal cestodes bioaccumulate higher levels of polychlorinated biphenyls (PCBs) than their hosts.…”