Parasites of the Brazilian flathead Percophis brasiliensis reflect West Atlantic biogeographic regions

Abstract

With the aim of evaluating the utility of marine parasites as indicators of zoogeographical regions in the South West Atlantic, we analyzed data on assemblages of long-lived larval parasites of 488 specimens of Percophis brasiliensis distributed in 11 samples from nine localities covering the entire distribution of the species in the Argentine biogeographical Province. Near half a million long-lived parasite individuals belonging to 17 species present in the whole sample displayed clear latitudinal patterns. Data for parasite assemblages at infracommunity and component community levels were analysed in relation to the geographical distance. Significant similarity decay of parasite assemblages over distance was observed, with those based on abundances and mean abundances showing departures from predicted values of regressions. These departures were represented by higher dissimilarities between samples coming from different zoogeographical regions than between those caught within the same region, independently of the distance separating them. Consequently, zoogeographical regions were identified in a distance-decay context. Multivariate analyses corroborated a close fit of similarity between assemblages to existing zoogeographical classifications. Regressions representing distance decay of similarity, and the identification of their outliers, can therefore shed light on the existence of discontinuities or uniformities in the geographic distribution of parasite assemblages and, in turn, in the zoogeography of their fish hosts.

Influence of confluent marine currents in an ecotonal region of the South-West Atlantic on the distribution of larval anisakids (Nematoda: Anisakidae)

“…However, nMDS analyses showed that Z. conchifer departed from the general zoogeographical pattern displayed by the other samples, which in turn, agreed with biogeographical schemes recognized in the South-West Atlantic [ 48 ]. Indeed, the apparent separation of samples in two groups corresponding to the Bonaerensean District of the Argentine Province and to the Magellanic Province, characterized by low and high values of prevalence, respectively, confirms the value of larval Anisakis as zoogeographical indicators [ 9 , 34 ]. On the other hand, the two ecotonal hake samples between these two zoogeographical units (Mh3 and Mh4) clustered with Magellanic and Bonaerensean samples, respectively, indicating a higher influence of each mass of water on the populations of Anisakis in fish at these transitional zones.…”

“…Lanfranchi et al [ 29 ] included data on other host species recognized as harbouring parasite assemblages representative of neighbouring zoogeographical regions, characterized by these masses of water [ 9 , 33 , 34 ]. These waters, with subtropical and sub-Antarctic origins, affected the structure of parasite communities in the ecotone by acting as sources of infective stages of helminth species (acanthocephalans, nematodes, cestodes) typical of adjacent zoogeographical units, which were considered as reliable indicators to define such transitional regions.…”

Parasites of Percophis brasiliensis (Percophidae) benefited from fishery regulations: Indicators of success for marine protected areas?

“…The parasite fauna of P. brasiliensis is probably one of the best known in the south‐western Atlantic (Braicovich et al, 2017; Braicovich & Timi, 2008, 2010). In new samples collected 13 years after prior work, and from the southern distribution area, two new parasites were recorded, yielding a total of 38 species of parasites known for this host.…”

“…However, in this case, changes related to short‐term or seasonal causes were avoided by restricting comparative analyses to larval parasites, all of them living in the body cavity or internal tissues. Members of this guild are persistent for long periods or even for the entire life of hosts (Braicovich et al, 2017; Lester & MacKenzie, 2009; Timi & MacKenzie, 2015), and consequently, seasonality is not expected to occur. Furthermore, both samples from ER (2005 and 2018) were caught during the same season (October), further reducing any expected influence of seasonality.…”

“…Prevalence and mean abundance for each parasite species in each locality were calculated following Bush, Lafferty, Lotz, and Shostak (1997); long‐lived larval parasites were selected for all subsequent analyses since these parasite species are persistent for long periods or even for the entire life of hosts, and therefore are more reliable for comparisons (Braicovich, Pantoja, Pereira, Luque, & Timi, 2017). Indeed, as long‐lived parasites live in the body cavity or encysted in tissues, no seasonal variability in the parasite loads is expected for these larvae; therefore, their burdens and community structure remain stable throughour host migratory routes (Timi & MacKenzie, 2015).…”