Helminth Parasite Communities of Two Scorpaena spp . ( Scorpaenidae ) From Reefs of Veracruz , Mexico

Scorpaena brasiliensis and S. plumieri are relevant fish species in reef systems, but little is known about their parasitic helminth communities and their structure. This paper describes such community in terms of species richness and diversity. A helminthological study was conducted on 33 specimens of S. brasiliensis and 36 S. plumieri, captured in the Pajaros and Cabezo Reefs, in the Veracruz Reef System National Park (VRSNP), Veracruz, Mexico. The helminth community structure was analyzed in both host species. A total of 10 parasitic species was registered in S. brasiliensis (5 digeneans, 1 cestode, 3 nematodes, 1 acanthocephalan), while S. plumieri hosted 11 species (4 digeneans, 1 monogenean, 1 cestode, 4 nematodes, 1 acanthocephalan), with 8 common species. The species with the highest prevalence were Pseudocapillaria (Icthyocapillaria) sp., with 18.2% and 19.4% in S. brasiliensis and S. plumieri, respectively. Component community richness for S. brasiliensis was S = 10, with Shannon index diversity value of H’ = 2.08. For S. plumieri, such values were of S = 11 and H’ = 1.91. Richness and diversity in the component and infracommunity levels for both hosts are lower than in other parasite communities of marine fishes in the southern Gulf of Mexico.


Introduction
Scorpenid fish are associated to rocky substrates and reef formations in the West Atlantic Ocean, and are distributed from the US to Brazil, including the Gulf of Mexico and the Caribbean Sea (Smith-Vaniz et al., 1999).Some species are popular due to sting injuries inflicted to unwary bathers (Field-Cortazares & Calderon-Campos, 2010), but most species have no commercial relevance given their low capture volumes, i.e., S. plumieri (Haddad et al., 2003;Fuentes-Mata & Espinoza-Pérez, 2010).Information related to parasitic helminths on these hosts is scarce (Cervigón et al., 1992).Available records include Helicometrina nimia in S. agassizii; H. nimia, Neopecoelus scorpaenae and Sterrhurus floridensis in S. brasiliensis; Derogenes varicus, Opecoelina scorpaenae and Pseudopecoelus vulgaris in S. cristulata; N. scorpaenae in S. grandicornis; Sterrhurus sp. in S. inermis; B. scorpaenae, H. nimia, S. floridensis in S. plumieri, all from Florida, USA (Manter, 1947); B. scorpaenae in S. plumieri from Louisiana, USA (Corkum, 1967); Lecithochirium parvum and L. microcercus in S. plumieri from Puerto Rico (Dyer et al., 1985); H. nimia in S. plumieri from Puerto Rico (Siddiqi & Cable, 1960) and Brazil (Travassos et al., 1967;Roumbedakis et al., 2014); Pseudopecoelus scorpaenae in S. plumieri from Mexico (Pérez-Ponce de León et al., 2007).On the other hand, little is known about the community structure of helminth parasites in these hosts, as compared to other marine fish, such as carangids and lutjanids from the Southern Gulf of Mexico (Montoya-Mendoza et al., 2014, 2016, 2017a), or other commercially relevant species from the Caribbean region (Aguirre-Macedo et al., 2007).In this report we describe the helminth community of S. brasiliensis and S. plumieri, in terms of species richness and diversity.

Sampling Procedures
From March to November, 2014, 33 specimens of S. brasiliensis and 36 of S. plumieri were collected for helminthological examination.Fish were captured with spear and SCUBA diving at 5-10 m depth in Pajaros Reef (19°18′33″N,96°08′33″W) and Cabezo Reef (19°03′07″N,95°52′05″W), in the Veracruz Reef System National Park (VRSNP), state of Veracruz, Mexico.Fish specimens were kept in plastic containers with ice and transported to the lab for examination within 24 hours post-capture.Tissues and organs were reviewed using a stereomicroscope.The external examination included skin, scales, fins, gills, eyes, nostrils, mouth, and anus.Gills were removed and analyzed separately in Petri dishes with seawater.Internal examination included mesenteries, liver, kidney, and gonads.The whole digestive system was placed in Petri dishes with 0.75% saline for examination.Helminths were fixed with hot 4% formalin and preserved in 70% ethyl alcohol, according to Lamothe (1997).Monogeneans, digeneans, cestodes, and acanthocephalans were stained using Mayer's paracarmine and Gomori's triple stain, and then dehydrated in a graded alcohol series, cleared with clove oil, and mounted whole in Canada balsam.Nematodes were studied on temporary slides and cleared in glycerin, after which they were preserved in 70% alcohol (Vidal-Martínez et al., 2001).Voucher specimens were deposited at the National Helminths Collection (Colección Nacional de Helmintos) (CNHE), Institute of Biology of the National Autonomous University, Mexico City.Prevalence (percentage of infected hosts) and mean intensity (mean number of parasites per infected fish), were calculated following Bush et al. (1997).

Sample Size
Helminth communities were analyzed at component community (all helminths in all individuals examined), and infracommunity (helminths in each single fish examined) levels (Holmes & Price, 1986;Bush et al., 1997).Sampling adequacy for the component community was evaluated with a procedure similar to that of the helminth parasites community as L. campechanus and L. synagris (Montoya-Mendoza et al., 2014;2016), using a randomized (100x) sample-based species accumulation curve computed in EstimateS (version 8.0 RK Colwell, http://viceroy.eeb.unconn.edu/estimates)(Moreno & Halffter, 2001).To determine the component community, we examined the asymptotic richness based on the Clench's model equation (Soberón & Llorente, 1993), as well as the final slope of the randomized species accumulation curve (Jiménez-Valverde & Hortal, 2003).Clench's model is described by the following function: where, V2 is observed richness, V1 is the number of hosts examined; a and b are curve parameters: a equals the new species adding rate, and b is a parameter related to the curve shape.These values were calculated iteratively using the EstimateS and Statistica (StatSoft, Inc., Tulsa, Oklahoma) software, as in Jiménez-Valverde and Hortal (2003).The slope of the cumulative species curve was calculated as a/(1 + b × n) 2 , where a and b are parameters above, and n is the number of hosts examined from a given component.Clench's model equation allows estimating the total number of species in a component as a/b.To determine the number of rare species missing at the component community level, the nonparametric species-richness estimator bootstrap was calculated from data observed, as recommended by Poulin (1998).The Shannon index of diversity (H'), was calculated for the component community as in Magurran (2004).Descriptors of infracommunity included the mean number of helminth species per fish, the mean number of helminth individuals per fish, and the mean value of the Brillouin's diversity index per fish (H).Similarity among two parasite communities was estimated using the Jaccard similarity index (Magurran, 2004).
The analysis of cumulative species curves for the component community suggested that the inventory of helminth species, when collecting 80% of the species, and the slope of the cumulative species curve for S. brasiliensis was 0.06.Thus, an asymptote was reached, and richness estimated by the Clench's model was 12 species (a = 1.13, b = 0.09; a/b = 12.5).For S. plumieri, when collecting 84% of the species, such value was 0.06, an asymptote was also reached, and richness estimated by the Clench's model was 13 species (a = 1.35, b = 0.09; a/b = 13.5).The value of the nonparametric species-richness estimator bootstrap (S. brasiliensis, Sb = 9; S. plumieri, Sb = 13) confirms that most, if not all, helminth species from the component community were recovered from both host species.

Component Community and Infracommunity
A total of 181 helminths was collected in both host species.Out of these, 73 were found in S. brasiliensis.
Infections ranged from 1 to 8 individuals per infected host.Richness of the component community was S = 10, and the Shannon index diversity value was H' = 2.08.For the infracommunity in S. brasiliensis, 12 hosts were parasite-free (36.3%), and richness ranged from 1 to 3 species of helminths per fish.Eleven hosts had a single helminth species; 8 hosts had 2, and 2 had 3.The average number of parasites species per individual host was 1.57±0.67,while the average number of helminth individuals per host was 3.47±2.33.The value of Brillouin's index for each infracommunity ranged from 0 to 0.76 with an average of 0.19±0.23.The other 108 helminths were found in S. plumieri.Infections ranged from 1 to 20 individuals per infected host.Richness of the component community was S = 11, and the Shannon index diversity value was H' = 1.91.The infracommunity for S. plumieri, 16 hosts were parasite-free (44.4%), richness ranged from 1 to 6 species of helminths per fish.10 hosts had 1 parasite species; 4 were infected by 2; 3 had 3; 1 had 4; 1 had 5; and 1 had 6.The average number of parasites species per individual host was 2.1±1.48,while the average number of helminth individuals per host was 5.4±6.9.The value of Brillouin's index for each infracommunity ranged from 0 to 1.15 with an average value of 0.31±0.38.In the community components, we found a high similarity (Jaccard similarity index, IJ = 0.615), among the parasite communities of S. brasiliensis and S. plumieri, as they share eight species (Table 1).

Discussion
Adding the previous known parasites records for S. brasiliensis, which are: H. nimia, L. floridense, P. scorpaenae, S. musculus (Overstreet et al., 2009), and those reported in this investigation, the updated inventory of helminths for this host reached 12 helminth species.For S. plumieri, parasites known were: B. scorpaenae, H. nimia, L. floridense, P. scorpaenae, and S. musculus (Overstreet et al., 2009), and with those found in this work, the inventory of helminths for this host reached 13 helminth species.This investigation added 8 new host records for each host species, and 3 new locality records.In addition, both hosts share parasites with other scorpaenids, e.g., L. floridense in S. agassizii; B. scorpaenae and P. scorpaenae in S. grandicornis; and Derogenes sp. in S. maderensis (Overstreet et al., 2009).It has to be noted that they even share parasites records (L.floridense, metacercarie of Didymozoidae, larva of Tetraphyllidea, and Pseudocapillaria sp.), with the invasive scorpaenid Pterois volitans, the red lionfish, from the same locality (Montoya-Mendoza et al., 2017b).These observations showed that most adult parasites registered infest local scorpaenids, and that may be related to their distribution area, but now they can also be found in invasive scorpaenids, probably due to the transfaunal phenomenon displayed by larval forms.
On the other hand, our records of both parasite communities revealed that they are almost complete, but richness registered in both communities (S = 10, S. brasiliensis; S = 11, S. plumieri), is considered low, when compared to other hosts in this area, for example, carangids  , 2007), samples are quite similar as related to the number of parasite species, therefore, they can be identified as communities with mean richness and abundance.
Low richness values of parasite species are usually associated with the host vagility, given that fish with high vagilities, such as C. crysos, C. hippos or L. campechanus, have higher species richness, and those with low vagility, like our hosts, have lower values.However, low richness in parasite communities of hosts studied here, could be associated to parasitic-host relationships, considering that richness and abundance records for parasite communities in scorpaenids from other latitudes have been low, as in S. guttata (Love & Moser, 1983), S. notata, S. porcus and S. scrofa (Sasal et al., 1997;Öktener, 2014).
Another aspect that should be pointed out due to its effects on the parasite community richness, is the presence and distribution of intermediate hosts, and the definitive host itself, especially those who are a part of the host diet, based on prey such as penaeids, stomatopods, crabs, fish, and octopuses (Randall, 1967).They may be infected with larval stages of parasites, and considering that hosts have similar food sources, the similarity of 61.5% of the parasite species composition between both communities, could be explained (Deardoff & Overstreet, 1981;Sasal et al., 1997;Aguirre-Macedo et al., 2007).On the other hand, the presence of parasite larvae suggests that both scorpaenid species are at an intermediate level in the marine food web, as smaller sizes are captured by predators, such as Dasyatis americana and some lutjanids (Randall, 1967).
Finally, data show that helminth communities of S. brasiliensis and S. plumieri have lower richness and diversity values than those found in other marine fish from the Southern Gulf of Mexico and the Caribbean (Randall, 1967;Sánchez-Ramírez & Vidal-Martínez, 2002;Espínola-Novelo et al., 2013;Montoya-Mendoza et al., 2014, 2016, 2017a).The composition, richness, and diversity of helminth communities in S. brasiliensis and S. plumieri could be mainly associated to their distribution, intermediate and definitive hosts, feeding habits and low host vagility.