Cambios en la comunidad de peces por efecto del desarrollo costero en el Parque Nacional Huatulco (México) / Changes in fish communities from the effect of coastal development in Huatulco National Park (Mexico)

Resumen El incremento del aporte de sedimentos desde tierra derivado del desarrollo costero y urbanización ha producido efectos adversos en la estructura y función de los arrecifes coralinos. El objetivo de este estudio fue conocer la magnitud de disturbios por aportes excesivos de sedimentos en la comunidad íctica de arrecifes coralinos de las bahías Maguey y Violín del Parque Nacional Huatulco (México). Los muestreos de peces se realizaron antes y después de disturbios ocasionados por aportes de sedimentos asociados a obras de desarrollo costero. Como indicadores de cambios en las comunidades de peces se utilizaron el número de especies, diversidad, equidad y dominancia antes y después de la perturbación. El análisis se realizó mediante pruebas de comparación de medias, análisis de similitud (ANOSIM) y análisis de porcentaje de similitud (SIMPER). En ambas localidades, se observó, que, excepto la dominancia, la diversidad, equidad, abundancia y número de especies fueron mayores previos a la perturbación. En Maguey se observaron diferencias significativas en la equidad y dominancia (U=28, p=0.0401; U=24, p=0.0472), así como en la composición de especies y la abundancia (ANOSIM=0.35, p=0.009). El análisis de porcentaje de similitud (SIMPER) indicó que posterior a la perturbación, el 46 % de especies presentaron una disminución en su abundancia, destacó la ausencia de Prionurus laticlavius, así como el decremento en la abundancia de: P. punctatus, Cirrhitichthys oxycephalus, Microspathodon dorsalis, Lutjanus novemfaciatus y Stegates acapulcoensis. La inadecuada planeación y ejecución de proyectos de desarrollo costero que propiciaron aporte excesivo de sedimentos al mar determinaron cambios negativos en las comunidades coralinas de Maguey y Violín, cuyo efecto fue observado en la composición de especies, abundancia, equidad y dominancia de la comunidad de peces de Maguey.(AU)

Abstract Coastal development and urbanization have increased the sediments that are washed from the land surface, producing adverse effects on the structure and functioning of coral reefs. The objective of this study was to identify the degree to which excessive sediments have disturbed the fish community in the coral reefs in the Maguey and Violin bays, located in the Huatulco National Park (Mexico). Fish samples were collected before and after disturbances produced by sediments associated with coastal development projects. Indicators of changes in the fish communities included the number and diversity of species as well as equity and dominance before and after the disturbances. The analysis was performed through means comparison tests, similarity analysis (ANOSIM) and similarity percentage analysis (SIMPER). In both locations, it was observed that the diversity, evenness, abundance and number of species were higher prior to the disturbance, but not for dominance, which shows an inverse pattern. In Maguey, significant differences in evenness and dominance were observed (U = 28, p = 0.0401; U = 24, p = 0.0472), as well as in species composition and abundance (ANOSIM = 0.35, p = 0.009). The similarity percentage analysis (SIMPER) indicated that after the disturbance, more than 46 % of the species showed decreases in average abundance, highlighting the absence of Prionurus laticlavius, as well as the decrease in abundance of: P. punctatus, Cirrhitichthys oxycephalus, Microspathodon dorsalis, Lutjanus novemfaciatus and Stegates acapulcoensis. Inadequate planning and implementation of coastal development projects that contribute to the discharge of excessive sediments into the sea were determinants of negative changes in the coral communities in Maguey and Violin, whose effects could be seen in the composition of the species and the abundance, equity, and dominance of the fish community in Maguey.(AU)

Variación espacial en número de especies, abundancia y diversidad de peces en las Bahías de Huatulco, Oaxaca, México / Spatial variation in species number, abundance and diversity of fish in Huatulco Bays, Oaxaca, Mexico

Resumen Los peces arrecifales están adaptados a diferentes características de su hábitat, por lo tanto, las diferencias en composición y estructura pueden ser resultado de factores intrínsecos de cada sistema. En este trabajo se determinó el número de especies, abundancia y diversidad de la ictiofauna de las bahías de San Agustín, Riscalillo, Chachacual, Cacaluta, Maguey, Órgano, Violín y La Entrega. La caracterización de las comunidades de peces se realizó a través de la técnica de censos visuales, se realizaron351 transectos de 10 metros de longitud cada uno, entre enero 2009 y diciembre 2010. El análisis del número de especies, abundancia y diversidad de la ictiofauna reveló que los valores máximos fueron característicos de las bahías Maguey, La Entrega, Órgano y Violín; mientras que los valores mínimos fueron propios de San Agustín, Riscalillo, Chachacual y Cacaluta. Se detectaron diferencias significativas en la diversidad (Kruskal-Wallis= 18.71, P= 0.0091), así como en la composición y estructura de la ictiofauna entre bahías (ANOSIM= 0.278; P= 0.001). Se observó relación del número de especies de peces con el número de especies coralinas (Spearman= 0.591, P<0.05), no siendo así para el número de especies y abundancia de peces respecto al área coralina. El número de especies coralinas y disposición de la cobertura coralina en parches, determinan hábitats de mayor complejidad estructural, influyendo en el número de especies de peces. En las localidades que poseen infraestructura turística, se observó la influencia que ejercen las actividades acuáticas recreativas sobre el comportamiento, abundancia y diversidad de la ictiofauna. La información de esta investigación puede contribuir a la integración y mejora de estrategias de manejo, conservación y protección de los recursos naturales de la región.

Abstract Coral reef fish may adapt to their habitat characteristics, and the particular system intrinsic factors, may cause different fish compositions and structures. The present study aimed to determine the variation in number of species, abundance and diversity of fish communities in Huatulco bays of San Agustin, Riscalillo, Chachacual, Cacaluta, Maguey, Organo, Violín and La Entrega, from Oaxaca, Mexico. Fish communities were characterized between January 2009 and December 2010, with the use of visual census techniques. A total of 351 transects (10 x 2.5 m) were made, and for each one we analyzed the ichthyofauna species number, abundance and diversity. The analysis showed that for all variables, the highest values corresponded to Maguey, La Entrega, Órgano and Violín bays, while the lowest values corresponded to the San Agustín, Riscalillo, Chachacual and Cacaluta bays. The study identified significant differencesin diversity (Kruskal-Wallis= 18.71, P= 0.0091), and in the composition and structure of fish communities in the bays (ANOSIM= 0.278, P= 0.001). We observed a relationship between the number of fish species and number of coral species (Spearman= 0.591, P< 0.05), while no relationship was found between the coral reef area and the number of fish species or their abundances. The number of coral species and the patchy arrangement of the coral cover created habitats that are structurally more complex, which affects the number of fish species. In areas with developed tourist infrastructure, recreational aquatic activities were found to affect the ichthyofauna behavior, abundance and diversity. The new information of this study may contribute to create and improve management, conservation and protection strategies for this important area as a whole interconnected complex.

Ecological composition and distribution of the diatoms from the Laguna Superior, Oaxaca, Mexico.

A taxonomic study of diatoms was carried out in a tropical coastal lagoon. Material for this study consists of water samples obtained from February-March 1992 to November-December 2000. Qualitative and quantitative analyses showed the presence of 373 taxa of which the families Bacillariaceae (67 species) and Chaetocerotaceae (37 species) were the most abundant groups. The species Skeletonema costatum, Chaetoceros curvisetus, Coscinodiscus radiatus var. radiatus, Ditylum brightwellii, Thalassiosira eccentrica and Entomoneis alata were found associated with moderate water quality and forming blooms. In addition, a regional comparison between Mexico and South America of the identified species is given. For practical handling, indicative values obtained from their ecological composition are incorporated as well as a code of the floristic list. Achecklist of the species and their occurrence are given.

[Phytoplankton from Tehuantepec River, Oaxaca, Mexico and some biogeographical relationships]. / Fitoplancton del río Tehuantepec, Oaxaca, México y algunas relaciones biogeográficas.

Phytoplankton species collected from the limnetic to euryhaline sections of Tehuantepec River were identified, classified and compared with regional information from Mexico and South America. We collected 15 samples every three months from July 1997 through August 1998 with a 20 microm net and a Van Dorn bottle. Indicator values and a code checklist are included. A total of 58 families, 121 genera, 273 species, one subspecies, 75 varieties, 13 forms and one morphotype were identified in the taxa Bacillariophyta (42.0 %), Chlorophyta (29.0 %), Cyanoprocaryota (18.0 %), Euglenophyta (5.0 %), Dinophyta (3.0 %), Cryptophyta (2.0 %) and Chrysophyta (1.0 %). The predominant families were Scenedesmaceae (24 species), Oocystaceae (22), Bacillariophyceae (21), Chaetocerotaceae (15) and Euglenaceae (14). Five families, eight genera, 72 species, 45 varieties and eight forms are first records for Mexico. The species Chroococcus turgidus, Microcystis flosaquae and Pseudanabaena limnetica (which produce massive blooms or red tides) are important in this river of moderate water quality.

Fitoplancton del río Tehuantepec, Oaxaca, México y algunas relaciones biogeográficas / Phytoplankton from Tehuantepec River, Oaxaca, Mexico and some biogeographical relationships

Phytoplankton species collected from the limnetic to euryhaline sections of Tehuantepec River were identified, classified and compared with regional information from Mexico and South America. We collected 15 samples every three months from July 1997 through August 1998 with a 20 microm net and a Van Dorn bottle. Indicator values and a code checklist are included. A total of 58 families, 121 genera, 273 species, one subspecies, 75 varieties, 13 forms and one morphotype were identified in the taxa Bacillariophyta (42.0 %), Chlorophyta (29.0 %), Cyanoprocaryota (18.0 %), Euglenophyta (5.0 %), Dinophyta (3.0 %), Cryptophyta (2.0 %) and Chrysophyta (1.0 %). The predominant families were Scenedesmaceae (24 species), Oocystaceae (22), Bacillariophyceae (21), Chaetocerotaceae (15) and Euglenaceae (14). Five families, eight genera, 72 species, 45 varieties and eight forms are first records for Mexico. The species Chroococcus turgidus, Microcystis flosaquae and Pseudanabaena limnetica (which produce massive blooms or red tides) are important in this river of moderate water quality.

El fitoplancton recolectado en el río Tehuantepec con características limnéticas a eurihalinas se determinó, clasificó y comparó con información regional de México y Suramérica. Se incluyen valores indicadores y un código del listado florístico para facilitar el manejo de estas algas. Se determinó un total de 58 familias, 121 géneros, 273 especies, una subespecie, 75 variedades, 13 formas y un morfotipo, pertenecientes a las divisiones Bacillariophyta (42.0 %), Chlorophyta (29.0 %), Cyanoprocaryota (18.0 %), Euglenophyta (5.0 %), Dinophyta (3.0 %), Cryptophyta (2.0 %) y Chrysophyta (1.0 %). Las familias mejor representadas fueron Scenedesmaceae (24 especies), Oocystaceae (22), Bacillariophyceae (21), Chaetocerotaceae (15) y Euglenaceae (14). Se establecen nuevos registros para México: cinco familias, ocho géneros, 72 especies, 45 variedades y ocho formas. En este río, que presenta una moderada calidad del agua, sobresalieron las especies Chroococcus turgidus, Microcystis flosaquae y Pseudanabaena limnetica (como productoras de mareas rojas).

Reproducción, distribución y abundancia del pez Pseudupeneus grandisquamis (Perciformes: Mullidae), en el Golfo de Tehuantepec, México / Reproduction, distribution and abundance of the fish Pseudupeneus grandisquamis (Perciformes: Mullidae), in the Gulf of Tehuantepec, Mexico

As result of its biological and ecological strategies, Pseudupeneus grandisquamis is a dominant species in the demersal community of the Gulf of Tehuantepec, Mexico. Our main objective was to understand these strategies with respect to distribution, abundance and reproduction. We analyzed 5,175 individuals representing partial collections from five oceanographic expeditions between 1989 and 1990. It is a typical demersal marine species, with a wide distribution on the continental shelf. The highest abundance of P. grandisquamis occurs in March and November, around the 40 m isobath, facing the Superior-Inferior lake systems and Mar Muerto Lagoon. Reproduction occurred during all of the months studied, particularly from August to October, corresponding to the rainy season, when the salinity and temperature is lower. The presence of juveniles, principally in November and March, suggests a long period of recruitment; they are distributed mainly in the Superior-Inferior Lagoons, which serves as a nursery area where they remain until they are adults. The total female to male sex ratio was nearly 1:1 throughout the year. The maximum total length was 213 mm and the size at first maturity was 138 mm TL. The high abundance and reproduction occur when the gulf has a high level of ecological production, in accordance with the dynamics of the system, where the influence of coastal lagoons is important. Protection strategies for the area above the continental shelf of the Gulf of Tehuantepec are recommended for the estuary processes and for the reproduction and rearing of a large number of species, including P. grandisquamis.

Como resultado de sus estrategias biológicas y ecológicas, el pez Pseudupeneus grandisquamis es una especie dominante en la comunidad demersal del Golfo de Tehuantepec. Nuestro principal objetivo fue conocer estas estrategias con base en su distribución, abundancia y reproducción. Se analizaron un total de 5 175 individuos que forman parte de las recolectas de peces obtenidas en cinco cruceros oceanográficos realizados en el Golfo de Tehuantepec, México, entre 1989-1990. Es una especie demersal típicamente marina, con amplia distribución en la plataforma continental. La mayor abundancia de P. grandisquamis se presenta en marzo y noviembre, alrededor de la isobata de los 40 m y frente a los sistemas lagunares Superior-Inferior y Laguna del Mar Muerto. La reproducción de la especie se presenta durante todos los meses analizados, principalmente durante los meses de agosto a octubre, correspondiente a la época de lluvias. La presencia de jóvenes, principalmente en noviembre y marzo, sugiere un amplio periodo de reclutamiento durante estos meses cuya distribución se refleja principalmente en el área influenciada por las lagunas Superior-Inferior, que representa un área de crianza. La proporción sexual total hembras:machos fue prácticamente 1:1. La talla máxima en la región es de 213 mm y la talla de primera madurez es de 138 mm LT. La alta abundancia y reproducción se presentan cuando el golfo tiene alta producción, acorde con la dinámica del sistema, donde tiene gran relevancia la influencia de las lagunas costeras. Se sugiere aplicar estrategias de protección a las zonas sobre la plataforma continental del Golfo de Tehuantepec influenciadas por procesos estuarinos y que representan áreas de reproducción y crianza para un gran número de especies, entre las que se encuentra P. grandisquamis.

[Reproduction, distribution and abundance of the fish Pseudupeneus grandisquamis (Perciformes: Mullidae), in the Gulf of Tehuantepec, Mexico]. / Reproducción, distribución y abundancia del pez Pseudupeneus grandisquamis (Perciformes: Mullidae), en el Golfo de Tehuantepec, México.

As result of its biological and ecological strategies, Pseudupeneus grandisquamis is a dominant species in the demersal community of the Gulf of Tehuantepec, Mexico. Our main objective was to understand these strategies with respect to distribution, abundance and reproduction. We analyzed 5,175 individuals representing partial collections from five oceanographic expeditions between 1989 and 1990. It is a typical demersal marine species, with a wide distribution on the continental shelf. The highest abundance of P. grandisquamis occurs in March and November, around the 40 m isobath, facing the Superior-Inferior lake systems and Mar Muerto Lagoon. Reproduction occurred during all of the months studied, particularly from August to October, corresponding to the rainy season, when the salinity and temperature is lower. The presence of juveniles, principally in November and March, suggests a long period of recruitment; they are distributed mainly in the Superior-Inferior Lagoons, which serves as a nursery area where they remain until they are adults. The total female to male sex ratio was nearly 1:1 throughout the year. The maximum total length was 213 mm and the size at first maturity was 138 mm TL. The high abundance and reproduction occur when the gulf has a high level of ecological production, in accordance with the dynamics of the system, where the influence of coastal lagoons is important. Protection strategies for the area above the continental shelf of the Gulf of Tehuantepec are recommended for the estuary processes and for the reproduction and rearing of a large number of species, including P. grandisquamis.