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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

Acapulco, offers for international tourism a variety of mollusks that are delightful to the palate and a source of economic revenue for its residents; however there are no studies on the species consumed. Furthermore, data from the State agencies responsible for registration of these products are unclear. This work is aimed to develop an inventory of Gastropoda, Bivalvia and Polyplacophora marketed as food, to gain knowledge on the species native to Acapulco and the introduced ones. The places that sell shellfish were interviewed from 2008 to 2011 in order to determine the geographical origin of their products being offered. We identified 42 species: 15 species of gastropods are captured locally and three are introduced. On Bivalvia, seven species are caught locally and 16 are introduced. There are Bivalvia species caught locally; however, their capture is now unaffordable. It is likely that this situation is due to overfishing and/or the transmission of diseases or parasites caused by the introduction of foreign living organisms to Acapulco. Within the list of species caught locally, there are some listed as of subject protection; all of these organisms are exploited in Acapulco without control. The wealth of marine mollusks for human consumption in Acapulco is very high. The capture does not satisfy local market demand and the amount of introduced species is very high. It is necessary to make a diagnostic analysis of mollusk fishing industry in the state of Guerrero, also implement a management program, including the sanitary measures and control of introduced species, as they arrive alive and stay alive in the waters of Acapulco. A significant number of native species that have aquaculture potential should be studied for commercial culture practice as well as to conduct studies on their biology on those species that are considered over-exploited and allow recovery of the species in its habitat.

An important part of the fishing activity in Mexico is carried out in the coastal strip and has a strong social, economic and ecological importance. In the state of Guerrero, mollusks fishing is coastal and craftwork activity focused on a small number of species and without information on biology and reproductive or ecological aspects for most species caught. This research was carried out in the Costa Chica region, Guerrero, Mexico and the aims were: 1) To analyze the socioeconomic features of cooperative societies of fishing production; and 2) To know the diversity of mollusks caught by coastal fishing and the species that have the greatest importance in fishing. From February to April 2013-2015, seven fish coop units, four piers and places where seafood is sold were visited. For the socioeconomic analysis and the determination of the species that have more importance in the coastal fishing, a total of 67 surveys were applied. In order to determine the cast of species, the specimens captured by the fishermen were used, which were identified and counted. A total of 67 interviews were analyzed and an average of $1806.00 was estimated as weekly economic income just as a product of fishing, it was also estimated that on average the fishermen work 4.3 days a week. Fisheries cooperatives market most of their produce directly to restaurateurs and locals on the piers. Replacement of older adults by young fishermen from the same region was observed, most are adults between 22 and 39 years old. 25 species of mollusks of economic importance were registered for the coastal fishermen of the Costa

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Riqueza, composición y diversidad de la comunidad de moluscos asociada al sustrato rocoso intermareal de playa Parque de la Reina, Acapulco, México Abstract.-The information available about marine biodiversity in the State of Guerrero, Mexico, is scarce as designated by the National Commission for the Conservation and Use of Biodiversity. To gain on this issue, this work was carried on at the rocky intertidal zone of Parque de la Reina beach, Acapulco, which is located in the Priority Region for Marine Conservation and Biodiversity Use Number 32. The objective was to establish the mollusks species richness, community structure, determine the density and degree of species occurrence, composition by size and diversity. The sampling area was 10 m -2 and the sampling unit was 1 m -2 . Fifty eight species were identified, with 4 new records for the intertidal rocky shores of Acapulco. The best represented families were: Muricidae, Ischnochitonidae, and Mytilidae. The observed density was of 207.55 m -2 . Twenty one species were rated as dominant. Macrocypraea cervinetta had the highest size. The mollusks richness was high, as is expected in the tropics. The constant and dominant species accounted for 55.16% of the total, and considered as representative of the community. The density found was higher than has been previously reported for the State of Guerrero; the type of substrate is one of the determining factors defining species richness and abundance. Key words: Check list, degree of occurrence, dominance, size and recordsResumen.-El conocimiento de la biodiversidad marina en el Estado de Guerrero, México es escaso, lo que es señalado por la Comisión Nacional para la Conservación y Uso de la Biodiversidad. Para avanzar en este conocimiento, se trabajó en el intermareal rocoso de Playa Parque de la Reina, Acapulco, que se encuentra ubicada en la región marina prioritaria para la conservación y uso de la biodiversidad número 32. El objetivo fue determinar la riqueza de especies de moluscos, conocer la composición de la comunidad, la densidad, el grado de aparición de las especies, la composición por tallas y la diversidad. El área de muestreo fue de 10 m -2 y la unidad de muestreo fue 1 m -2 . Se identificaron 58 especies, 4 nuevos registros para el intermareal rocoso de Acapulco. Las familias más representadas fueron: Muricidae, Ischnochitonidae, y Mytilidae. La densidad fue de 207,55 organismos m -2 . Fueron dominantes 21 especies. Macrocypraea cervinetta presentó la mayor talla. La riqueza de moluscos fue alta, coincidiendo con lo esperado en una zona tropical. Las especies dominantes y constantes representaron el 55,16%, y se consideran representativas de la comunidad. La densidad encontrada es la más alta que se ha reportado para Guerrero, México y el tipo de sustrato es uno de los factores determinantes que define la riqueza de especies y la abundancia.

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.

Demography of the snail Plicopurpura pansa (Neotaenioglossa: Muricidae) and constitution of the associated mollusk community, in Guerrero, Mexico. We quarterly sampled the molluskan community of Playa Ventura, Guerrero, Mexico. Sample size (20 m 2 in 1m 2 units) was determined by the spatial distribution pattern of Plicopurpura pansa using a negative binomial distribution. The density of the P. pansa was 5.19 snails/m 2 and the sex ratio near 1:1. The average size was 20.10 mm (most females were 10.5 to 27.0 mm; most males 12.0 to 27.0 mm). Density was high and small sized dominated. Mean size varied with time.