Ma. Leopoldina Aguirre-Macedo

A checklist of metazoan parasites of fish from Tres Palos Lagoon, Guerrero, Mexico

An extensive survey of helminth parasites in fish species from Tres Palos Lagoon, in Guerrero, Mexico, resulted in identification of 39 metazoan parasite species (37 helminth and 2 crustaceans) in 13 fish species (n = 1,498). Specimen collection in this coastal lagoon was done between April 2000 and November 2003. Digenean species (18, 8 adult and 10 metacercariae) dominated the parasite fauna. The most widespread species of parasite were: Contracaecum sp. (Nematoda), Pseudoacanthostomum panamense, Austrodiplostomumcompactum, Ascocotye (Phagicola) longa (Digenea), Neoechinorhynchusgolvani (Acanthocephala), Ergasilus sp. (Copepoda), and Argulus sp. (Branchiura). Parasite fauna species composition exhibited a clear freshwater influence as 56.4% (22 of 39) of the identified species have a freshwater distribution in Mexico. For 32 of the parasite species, this report constitutes the first geographical host record for Tres Palos Lagoon, Guerrero, Mexico.

The structuring process of the macroparasite community of an experimental population of cichlasoma urophthalmus through time

The structuring process of the macroparasite community of caged Cichlasoma urophthalmus was studied over time using sentinel fish. Three thousand uninfected cichlids were stocked in floating cages introduced into a quarry in which a wild population of the same species was present. Caged and wild cichlids were sampled monthly over 6 and 7 months, respectively. Seventeen macroparasite species were found in the wild C. urophthalmus population, ten of which were detected in the caged population after 6 months. Early infections were by those species that were more frequent and abundant in the wild population, while helminths with a low prevalence and abundance in the wild appeared later in the caged fish population. The results suggested that the structuring process of the macroparasite community of caged C. urophthalmus followed a predictable pattern, in which those species that were most frequent and abundant in the wild were the first to establish in sentinel fish.

Rainfall induces time-lagged changes in the proportion of tropical aquatic hosts infected with metazoan parasites

Rainfall serves as a powerful driving force, shifting temporal abundance and prevalence patterns in parasites and free-living aquatic organisms in tropical environments. However, there is a lack of sound evidence showing the temporal scales at which rainfall influences infection parameters of parasites in the tropics either directly by affecting the parasite life cycle or indirectly by modifying host population abundance. In the present study, we demonstrate that changes in rainfall patterns lead to changes in the proportion of infected hosts with several parasite species, causing immediate or lagged favourable conditions for an increase in levels of infection. However, the temporal scale of the influence of rainfall varied depending on the ecological characteristics of aquatic ecosystems. Despite the environmental heterogeneity and stochastic events (storms and hurricanes) which affect the study sites, the proportion of infected hosts shows frequency cycles on a yearly scale, suggesting that environmental changes are within the range of variability that naturally occur at the study sites. We propose that the incorporation of stochastic events into long-term predictive models is crucial for understanding the potential effects of global climate change on infection parameters of tropical parasites.

Helminth communities of four commercially important fish species from Chetumal Bay, Mexico

The relative importance of ecology and evolution as factors determining species richness and composition of the helminth communities of fish is a matter of current debate. Theoretical studies use host-parasite lists, but these do not include studies on a temporal or spatial scale. Local environmental conditions and host biological characteristics are shown to influence helminth species richness and composition in four fish species (Eugerres plumieri, Hexanematichthys assimilis, Oligoplites saurus, and Scomberomorus maculatus) in Chetumal Bay, Mexico. With the exception of H. assimilis, the helminth communities had not been previously studied and possible associations between environmental and host biological characteristics as factors determining helminth species richness and composition using redundancy analysis (RDA) are described. Thirty-four helminth species are identified, with the highest number of species (19 total (mean = 6.3 +/- 2.1)) and the lowest (9 (4.0 +/- 1.0)) occurring in H. assimilis and S. maculatus, respectively. The larval nematodes Contracaecum sp. and Pseudoterranova sp. were not only the helminth species shared by all four host species but also were the most prevalent and abundant. Statistical associations between helminth community parameters and local ecological variables such as host habitat use, feeding habits, mobility, and time of residence in coastal lagoons are identified. Phylogeny is important because it clearly separates all four host species by their specialist parasites, although specific habitat and feeding habits also significantly influence the differentiation between the four fish species.

Parasite Survey of the Eastern Oyster Crassostrea virginica in Coastal Lagoons of the Southern Gulf of Mexico

A parasitological study of the eastern oyster Crassostrea virginica from 11 coastal lagoons in the southern Gulf of Mexico in dry and rainy seasons between late 1999 and early 2001 revealed the presence of 36 bacterial, 2 protozoan (Nematopsis prytherchi and Perkinsus marinus), and 4 helminth species (Urastoma cyprinae, Proctoeces maculatus, a Bucephalus sp., and a Tylocephalum sp.). The prevalence and mean abundances for the protozoa and helminths varied widely between locations but were generally below 50%. Nematopsis prytherchi and the Tylocephalum sp. were the most prevalent species (values were above 60% in most locations). Perkinsus marinus was present in oysters of eight of the coastal lagoons and had low prevalence (<30%) in almost all samples. All identified protozoa and helminths are widely distributed in the Gulf of Mexico and are common oyster parasites. Only P. marinus and the Bucephalus sp. were associated with damage to host tissues. In addition to these parasites, Rickettsia-like bacteria were found in the digestive gland and gills and viral gametocytic hypertrophy inclusions in the gonads by histological examination.

Philometra (Ranjhinema) salgadoi n. sp. (Nematoda: Philometridae) from the ocular cavity of the red grouper Epinephelus morio (Pisces: Serranidae) from the yucatan peninsula, Mexico.

A new nematode species, Philometra (Ranjhinema) salgadoi n. sp., is described from females found in the ocular cavity of the red grouper (Epinephelus morio) from the Mexican coast of the Gulf of Mexico (type locality Telchac, Yucatán). The nematode is characterized by the presence of 8 conspicuously large, crescent-shaped, fleshy cephalic papillae of the external circle and 2 small, subterminal papilla-like projections on the caudal end. Another philometrid species, Philometroides belousae n. sp., is established by indication for P. parasiluri (Yamaguti, 1935) sensu Ermolenko, 1984; its adult females are parasitic in the subcutaneous tissues of Percottus glehni in the Russian Far East.

Biological effects of environmental pollutants in American Oyster, Crassostrea virginica: a field study in Laguna de Terminos, Mexico

The response of Crassostrea virginica to a complex mixture of toxic contaminants was studied at four sites in Laguna de Terminos, Mexico. Contaminants assessed were heavy metals, organochlorine compounds, and hydrocarbons. Biomarkers (cholinesterase activity, neutral red retention, and metallothionein), histopathology and prevalence of Perkinsus marinus were used to evaluate the effects of contaminants. The resultant contaminant body burden was moderately as high as a whole, and biomarker levels were also moderate. Oedema in the gills and systemic haemocytosis were the only histopathological lesions observed. P. marinus was never evidenced in the oyster tissues examined. Statistical results from principal components analysis show that metallothioneins are positively correlated with copper and chromium, neutral red and oedema with chlordanes, pentachloroanisol, drins, polychlorobiphenyls and total pesticides, total hydrocarbons and polycyclic aromatic hydrocarbons, whereas cholinesterase activity is negatively correlated to Cu and Cr. The biomarkers used were sensitive indicators responding to moderate levels of pollutants.

Metazoan parasite community of blue sea catfish, Sciades guatemalensis (Ariidae), from Tres Palos Lagoon, Guerrero, Mexico.

The seasonal dynamic of the metazoan parasite community of the blue sea catfish (Sciades guatemalensis) from Tres Palos Lagoon, Guerrero, Mexico, was studied at the component community and infracommunity levels. A total of 382 fish were collected during the regional dry and rainy seasons (a total of seven seasons) between April 2000 and September 2007. Nine helminths were collected: Neotetraonchus sp., Pseudoacanthostomum panamense, Austrodiplostomum compactum, Clinostomum complanatum, Metadena sp., Pseudoleptorhynchoides lamothei, Neoechinorhynchus cf. golvani, Hysterothylacium perezi, and Contracaecum sp. The infection dynamics of some dominant helminths was influenced by environmental changes generated by the dry/rainy season cycle. Nested (non-random) species composition was observed in the infracommunities during almost all of the sample period. Variation in the intensity of nestedness was attributed to a sequential colonization process over time by the dominant helminths.

Neotropical Monogenoidea. 45. Revision of Diplectanocotyla Yamaguti, 1953 (Diplectanidae) with Redescription of Diplectanocotyla megalopis Rakotofiringa and Oliver, 1987 on Atlantic Tarpon, Megalops atlanticus Cuvier and Valenciennes, from Nicaragua and Mexico

Abstract The diagnosis of Diplectanocotyla (Monogenoidea: Dactylogyridea) is emended, the genus is transferred to the Diplectanidae, and the Diplectanocotylidae is considered a junior synonym of the Diplectanidae. Diplectanocotyla megalopis is redescribed from gills of Atlantic tarpon, Megalops atlanticus (Megalopidae), from the Atlantic coasts of Nicaragua and Mexico (new host and locality records). Although D. megalopis was previously found on the Atlantic tarpon in Puerto Rico, the species from this host was originally misidentified as Diplectanocotyla gracilis. Diplectanocotyla is differentiated from other diplectanid genera by its members having a haptor with 2 central suckers (1 ventral, 1 dorsal) and paired ventral bars, a pair of squamodiscs with concentric rows of scales, a spined tegument of the posterior trunk and peduncle, an ovary looping the right intestinal cecum, and a vas deferens looping the left intestinal cecum.

First description of the male and redescription of the female of Philometra salgadoi Vidal-Martínez et al., 1995 (Nematoda: Philometridae) from the ocular cavity of the marine fish Epinephelus morio in Mexico

Abstract. A redescription of the female and the first description of the male of the philometrid nematode Philometra salgadoi Vidal-Martínez, Aguirre-Macedo et Moravec, 1995 are presented on the basis of specimens collected from the type host, the red grouper, Epinephelus morio (Valenciennes; Pisces: Serranidae), in the Gulf of Mexico off the northern coast of Yucatán, Mexico. The morphology of this species is compared with that of related congeneric species.