Mesopredatory fishes from the subtropical upwelling region off NW-Africa characterised by their parasite fauna

Abstract

Eastern boundary upwelling provides the conditions for high marine productivity in the Canary Current System off NW-Africa. Despite its considerable importance to fisheries, knowledge on this marine ecosystem is only limited. Here, parasites were used as indicators to gain insight into the host ecology and food web of two pelagic fish species, the commercially important species Trichiurus lepturus Linnaeus, 1758, and Nealotus tripes Johnson, 1865. Fish specimens of T. lepturus (n = 104) and N. tripes (n = 91), sampled from the Canary Current System off the Senegalese coast and Cape Verde Islands, were examined, collecting data on their biometrics, diet and parasitisation. In this study, the first parasitological data on N. tripes are presented. T. lepturus mainly preyed on small pelagic Crustacea and the diet of N. tripes was dominated by small mesopelagic Teleostei. Both host species were infested by mostly generalist parasites. The parasite fauna of T. lepturus consisted of at least nine different species belonging to six taxonomic groups, with a less diverse fauna of ectoparasites and cestodes in comparison to studies in other coastal ecosystems (Brazil Current and Kuriosho Current). The zoonotic nematode Anisakis pegreffii occurred in 23% of the samples and could pose a risk regarding food safety. The parasite fauna of N. tripes was composed of at least thirteen species from seven different taxonomic groups. Its most common parasites were digenean ovigerous metacercariae, larval cestodes and a monogenean species (Diclidophoridae). The observed patterns of parasitisation in both host species indicate their trophic relationships and are typical for mesopredators from the subtropical epi- and mesopelagic. The parasite fauna, containing few dominant species with a high abundance, represents the typical species composition of an eastern boundary upwelling ecosystem.

Multidecadal Changes in Marine Subsurface Oxygenation Off Central Peru During the Last ca. 170 Years

“…However, several global models fail to reproduce recent regional deoxygenation trends and differ in the prediction of future regional trends, particularly in the tropics where most of OMZs are hosted (Schmidtko et al, 2017). The Peruvian upwelling system is one of the most productive areas of the world ocean (Chávez and Messié, 2009) and is associated with a permanent, intense and shallow OMZ (Gutiérrez et al, 2008;Graco et al, 2017). The source of low oxygen waters and nutrients that feeds coastal upwelling is the Peru-Chile Undercurrent (PCUC; Montes et al, 2014).…”

Occurrence of Anisakis pegreffii (Nematoda: Anisakidae) Larvae in Imported John Dory (Zeus faber) from Senegalese Coast Sold in Turkish Supermarkets

“…Similarly, Anisakis larvae in P. prayensis and P. caeruleostictus from the ECA (off Senegal) have not been reported before [36]. Moreover, A. pegreffii, A. typica and A. physeteris have been recently reported in Trichiurus lepturus and Nealotus tripes from Senegalese coast [1].…”

Investigating food assimilation in a carnivorous teleost by stable isotopes analysis: the case of ribbonfish off south-east Brazil

“…This teleost is a widely distributed mesopredator in tropical and subtropical latitudes, forming large shoals in brackish and marine waters up to 350 m depth, being more common up to 120 m depth (Martins & Haimovici, 1997; Alt et al ., 2018; Froese & Pauly, 2019). Mesopredators, such as the ribbonfish, are medium-sized predators that drive community structure through predation on small prey.…”

“…There is size disparity among conspecifics, with diet shift during the ontogeny: juveniles, sub-adults and small adults up to 100 cm length feed mostly on euphausiids, small pelagic planktonic crustaceans and small fishes, whereas adults over 100 cm length feed mainly on fish, squids and crustaceans (Nakamura & Parin, 1993). Adult cannibalism of juveniles is reported for the ribbonfish (Martins et al ., 2005; Bittar et al ., 2008; Liu et al ., 2009; Cruz-Torres et al ., 2014), although it is not a general rule (Yan et al ., 2011; Alt et al ., 2018). Adults and juveniles display opposite vertical migration in the water column that minimizes feeding competition.…”