No abstract

In the tropics, variations in the structure and species composition of marine fish parasite communities over several years have received limited attention. Changes in water temperature in the tropics are not as extreme as in temperate climes, and the processes that generate variations in these parasite communities are as yet unclear. The parasite communities in populations of Parapsettus panamensis from four locations on the south-central Pacific coast of Mexico were quantified and analyzed. Four hundred forty-six fish were collected over a 6-year period (2012; 2013; 2016a, b; and 2017). Twenty-three metazoan parasite species were recovered and identified: three species of Monogenea (present as adults); eight species of Digenea (adults); one species of Acanthocephala (juveniles); one species of Cestoda (larvae); three species of Nematoda (two present as adults and one present as larvae); four species of Copepoda; and three species of Isopoda (two present as adults, and one present as larvae). At the component community level, parasite species richness varied significantly from 10 (Marquelia 2016) to 17 species (Acapulco Bay 2012). The component communities and infracommunities of P. panamensis exhibited a similar pattern: low species numbers, low diversity, and dominance by a single parasite species. Parasite community structure and species composition varied between sampling years and locations. The main factors responsible for these variations were host traits such as feeding behavior and body size, and occurrence of a set of distinctive parasite species. K E Y W O R D S marine fish, Mexico, Pacific coast, Parapsettus panamensis, parasites

Species composition and abundance of the phytoplankton community in Acapulco Bay, Mexico, were studied from May to December 2009. Samples were collected at 5 stations (4 coastal and 1 oceanic) at 3 depths (1, 5 and 10 m). Eighty-seven species were identified: 54 dinoflagellates, 32 diatoms and 1 silicoflagellate. The community was structured mainly by adiaphoric species, that is, species adapted to both neritic and oceanic environments. Species abundance and composition varied significantly during the sampling period due to increased nutrient concentrations in the rainy season. Dinoflagellate species were more abundant during the dry season, and diatom species dominated numerically during the rainy season.

This paper is a comparative study of Diplostomum (Austrodiplostomum) compactum (Lutz, 1928) in Nile tilapia Oreochromis niloticus (Linneo) from two fish farms and two nearby coastal lagoons in Guerrero state, Mexico. The higher infections levels in cultured tilapia than wild tilapia is attributed to higher fish densities in the culture systems and higher abundance of the snail Biomphalaria cf. havanensis (Pteiffer), first intermediate host of this parasite in freshwater and brackish water systems.

Species richness and similarity in metazoan parasite communities of fishes can be influenced by several biotic (age, body size, vagility, feeding and social behavior, among others), and local abiotic (temperature, salinity, etc.) factors. The parasite communities of three species of Oligoplites, marine fishes from the Pacific coast of Mexico, were quantified and analyzed. Four hundred sixty‐eight leatherjackets (O. altus, n=94; O. saurus, n=260; and O. refulgens, n=114) were collected from February 2016 to June 2017 from five locations. Twenty‐eight species of metazoan parasites were recovered and identified: four species of Monogenea (adults), nine of Digenea (seven adults and two metacercariae); two of Cestoda (larvae); four of Nematoda (two adults and two larvae); four of Acanthocephala (two adults, one juvenile, and one cystacanth); four of Copepoda; and one Pentastomida (larvae). At the component community level, species richness ranged from 9 in O. saurus to 19 in O. altus. Different species of helminth dominated the component communities of each species of host. Community composition and species richness of parasites differed among the three species of host, locations, and sampling years. Host feeding behavior, body size, and vagility had the most influence on these differences.

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The parasite community structure of the neotropical cormorant, Phalacrocorax brasilianus, from two lagoons (Coyuca and Tres Palos) from Guerrero state, México, was examined. Fourteen species of adult helminths (6,391 individuals) from 48 cormorants were identified: 9 digeneans, 1 acanthocephalan, 1 cestode, and 3 nematodes. A total of 11 species were collected in Coyuca Lagoon and 12 in Tres Palos Lagoon. Nine species co-occurred in cormorants of both lagoons but, with the exception of Contracaecum multipapillatum and Drepanocephalus olivaceus, species were not equally common in both lagoons. The prevalence values of six species of helminth and the mean abundance of four species varied significantly between lagoons, and C. multipapillatum was numerically dominant in both lagoons. The qualitative similarity between the two communities at the component level was 64%. All cormorants examined were infected, and parasite species richness was 3-5 in Coyuca and 4-9 in Tres Palos lagoon. The results indicate that both communities presented a similar structure at the component level, probably because the cormorants of both lagoons feed on the same species of fish and thus acquire almost the same species of parasites. Differences observed at the infracommunity level were attributed to variations in the degree of dominance of the particular species.

Se estableció el ciclo reproductivo del pargo lunarejo Lutjanus guttatus, un pez de gran importancia comercial. Los organismos se recolectaron mensualmente desde febrero de 1993 a diciembre de 1994. La proporción de sexos poblacional fue de 1M:0.96H y no se encontró una diferencia significativa (P≤0,05) de la proporción esperada de 1:1. Las gónadas se analizaron histológicamente y se describieron las fases de desarrollo gonadal. L. guttatus presenta un desarrollo asincrónico de las gónadas y es un desovador parcial. La actividad reproductiva estuvo presente todo el año aunque con dos períodos reproductivos principales (marzo-abril y agosto-noviembre) representados por altos porcentajes de gónadas categorizadas como maduras y en desove. Estos períodos coinciden con valores elevados del índice gonadosomático (IGS) y valores bajos del índice hepatosomático (IH). El factor de condición (FC) presentó una tendencia similar a la del IGS con los máximos valores durante la época de reproducción y disminuyendo hacia las épocas de reposo. Se considera que el IGS representa adecuadamente la actividad reproductiva y que puede haber una relación inversa entre la actividad reproductiva y el IH.