Environmental and anthropogenic factors affecting the probability of occurrence of Oncomegas wageneri (Cestoda: Trypanorhyncha) in the southern Gulf of Mexico

Abstract

BackgroundUnderstanding the environmental and anthropogenic factors influencing the probability of occurrence of the marine parasitic species is fundamental for determining the circumstances under which they can act as bioindicators of environmental impact. The aim of this study was to determine whether physicochemical variables, polyaromatic hydrocarbons or sewage discharge affect the probability of occurrence of the larval cestode Oncomegas wageneri, which infects the shoal flounder, Syacium gunteri, in the southern Gulf of Mexico.MethodsThe study area included 162 sampling sites in the southern Gulf of Mexico and covered 288,205 km2, where the benthic sediments, water and the shoal flounder individuals were collected. We used the boosted generalised additive models (boosted GAM) and the MaxEnt to examine the potential statistical relationships between the environmental variables (nutrients, contaminants and physicochemical variables from the water and sediments) and the probability of the occurrence of this parasite. The models were calibrated using all of the sampling sites (full area) with and without parasite occurrences (n = 162) and a polygon area that included sampling sites with a depth of 1500 m or less (n = 134).ResultsOncomegas wageneri occurred at 29/162 sampling sites. The boosted GAM for the full area and the polygon area accurately predicted the probability of the occurrence of O. wageneri in the study area. By contrast, poor probabilities of occurrence were obtained with the MaxEnt models for the same areas. The variables with the highest frequencies of appearance in the models (proxies for the explained variability) were the polyaromatic hydrocarbons of high molecular weight (PAHH, 95 %), followed by a combination of nutrients, spatial variables and polyaromatic hydrocarbons of low molecular weight (PAHL, 5 %).ConclusionsThe contribution of the PAHH to the variability was explained by the fact that these compounds, together with N and P, are carried by rivers that discharge into the ocean, which enhances the growth of hydrocarbonoclastic bacteria and the productivity and number of the intermediate hosts. Our results suggest that sites with PAHL/PAHH ratio values up to 1.89 promote transmission based on the high values of the prevalence of O. wageneri in the study area. In contrast, PAHL/PAHH ratio values ≥ 1.90 can be considered harmful for the transmission stages of O. wageneri and its hosts (copepods, shrimps and shoal flounders). Overall, the results indicate that the PAHHs affect the probability of occurrence of this helminth parasite in the southern Gulf of Mexico.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-1222-6) contains supplementary material, which is available to authorized users.

Occurrence of larvae of trypanorhynch cestodes in snappers (Lutjanidae) from northeast Brazil

“…A checklist published by Schaeffner & Beveridge (2014) records the occurrence of Oncomegas in Dasyatidae (whiptail stingrays). Larval forms of O. wageneri were found in Syacium gunteri (Shoal flounders) from the Gulf of Mexico by Vidal-Martínez et al (2015). To the best of our knowledge, there are no reports of Oncomegas or Pseudogrillotia infestation in lutjanid fish.…”

Thermal Change and the Dynamics of Multi-Host Parasite Life Cycles in Aquatic Ecosystems

“…However, while some parasites will undoubtedly benefit from altered climate scenarios, there is an increasing recognition of the diversity of possible responses, with many parasites likely to experience barriers to transmission under new environmental regimes, as host populations are impacted and conditions for transmission are altered ( Lafferty 2009 ; Lõhmus and Björklund 2015 ). Parasites have their own geographic limits that are constrained not only by host ranges but also by the physicochemical demands of free-living transmission stages ( Bozick and Real 2015 ), which are in direct contact with the aquatic environment and hence are susceptible to thermal or other perturbations ( Vidal-Martínez et al 2015 ). Furthermore, parasites that are transmitted through aquatic food webs not only require the presence of healthy populations of multiple host species, but also rely on ecological (i.e., predator–prey) interactions between these species for transmission to be fulfilled, with either (or both) of these being impacted under changing environments ( Lafferty 2009 ).…”

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

“…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).…”