Epiphytic diatoms of Macrocystis pyrifera (L.) C. Ag. from the Baja California peninsula, Mexico

Se observaron láminas de Macrocystis pyrifera y otras especies de algas pardas utilizadas para alimentar abulones en cultivo, con el ojetivo de determinar las especies epífitas de diatomeas. También se analizaron rocas y sedimentos con fines comparativos. Cocconeis cf. britannica fue la especie dominante y se observó en abundancia cubriendo las láminas de M. pyrifera. Otras especies importantes fueron Cocconeis speciosa, Gomphonemopsis pseudoexigua, así como Climacosphenia moniligera asociada acolonias de Navicula sp. Ninguna de estas especies se observó sobre las otras feofitas o en sustrato rocoso. A pesar de su abundancia, Cocconeis cf. britannica constituye un nuevo registro para las costas de la Península de Baja California, al igual que C. speciosa, Pseudodomphonema kamtschaticum y Rhoicosphenia adolphi, así como Okedenia inflexa, pero éste último para sustrato rocoso y sedimentos. La ausencia de Cocconeis cf. britannica en otras feofitas y otros sustratos de la zona sugiere que tiene una preferencia por M. pyrifera como sustrato. Esto debe ser considerado al estimar el valor nutricional de esta macroalga como alimento de abulones. Palabras clave: Diatomeas epífitas, Cocconeis cf. britannica, Macrocystis, Abulón, Nuevos registros, Península de Baja California

Species composition and seasonal changes in macroalgal blooms in lagoons along the southeastern Gulf of California

Species composition and seasonal changes in macroalgal blooms in six coastal lagoons highly impacted by human activities were tracked for the three seasons between May 2004 and April 2005. Though temperatures were lower during the cold season than during the dry and rainy seasons and some locations showed variations in salinity during the rainy season, nutrient concentrations showed no defined pattern and varied according to season and location. A total of 10 seaweed species and the cyanobacterium Microcoleus lyngbyaceus had biomasses > 1 g m(-2) dry weight, but only four species represented > 1% of the annual biomass. During the dry season, Spyridia filamentosa had the highest biomass (57.5 g m(-2)). During the rainy season, Gracilaria vermiculophylla was the most conspicuous and abundant species (64.0-291.0 g m(-2)) and during the cold season, Caulerpa sertularioides had the highest biomass (180.1 g m(-2)). Abundances of these species were higher than previously reported for this region. Correlation analyses showed a positive correlation between total phosphorus and the biomass of G. vermiculophylla, suggesting that this nutrient might be limiting its growth. C. sertularioides abundance had a positive correlation with N:P ratios, suggesting that high concentrations of nitrogen relative to low phosphorus levels favor its growth. These analyses revealed that nutrient concentrations are most likely to affect macroalgal growth, but temperature and salinity also play a role. This information may be useful for monitoring future blooms and determining changes overtime

Comparison of ecological diversity and species composition of macroalgae, Benthic macroinvertebrates, And fish assemblages between two tropical rocky reefs [Comparaci�n de la diversidad ecol�gica y composici�n de especies de ensambles de macroalgas, Macroinvertebrados bent�nicos y peces en dos arrecifes rocosos tropicales]

Within the marine environment, the rocky shores are recognized for their high species diversity and particularly transitional zones represent areas of biotic mix, promoted by historical and ecological natural variations that allow the presence of taxa from different regions and which present dissimilar biological traits. An extensive survey describes the benthic macroalgae, macroinvertebrates (molluscs, crustaceans, and echinoderms), and fish assemblages at two rocky reefs, Islas Marietas and near Tehuamixtle, in a tropical-temperate transitional zone in the Pacific waters of central Mexico using traditional ecological indices (richness, diversity, and evenness) and complementary taxonomic distinctness indices. Biological material inside each of ten randomly-chosen quadrants (25 � 25 cm) placed along two 50 m transects oriented parallel to the coastline, between 6 and 2 m depth was collected. From field collections, 204 species were identified: macroalgae (22), molluscs (55), crustaceans (78), echinoderms (11), and fish (38). The structure of macroalgae, macroinvertebrates and fishes was similar between sites. Species of macroalgae, molluscs, and fishes were more diverse in summer; crustaceans and echinoderms were more diverse in winter. Our results and the literature suggest a latitudinal pattern of lower seasonal changes in echinoderms and crustaceans at high latitudes, as compared to southern regions of the Mexican tropical Pacific. � 2014 Universidad de Valparaiso. All rights reserved

Comparison of ecological diversity and species composition of macroalgae, Benthic macroinvertebrates, And fish assemblages between two tropical rocky reefs [Comparación de la diversidad ecológica y composición de especies de ensambles de macroalgas, Macroinvertebrados bentónicos y peces en dos arrecifes rocosos tropicales]

Within the marine environment, the rocky shores are recognized for their high species diversity and particularly transitional zones represent areas of biotic mix, promoted by historical and ecological natural variations that allow the presence of taxa from different regions and which present dissimilar biological traits. An extensive survey describes the benthic macroalgae, macroinvertebrates (molluscs, crustaceans, and echinoderms), and fish assemblages at two rocky reefs, Islas Marietas and near Tehuamixtle, in a tropical-temperate transitional zone in the Pacific waters of central Mexico using traditional ecological indices (richness, diversity, and evenness) and complementary taxonomic distinctness indices. Biological material inside each of ten randomly-chosen quadrants (25 × 25 cm) placed along two 50 m transects oriented parallel to the coastline, between 6 and 2 m depth was collected. From field collections, 204 species were identified: macroalgae (22), molluscs (55), crustaceans (78), echinoderms (11), and fish (38). The structure of macroalgae, macroinvertebrates and fishes was similar between sites. Species of macroalgae, molluscs, and fishes were more diverse in summer; crustaceans and echinoderms were more diverse in winter. Our results and the literature suggest a latitudinal pattern of lower seasonal changes in echinoderms and crustaceans at high latitudes, as compared to southern regions of the Mexican tropical Pacific. © 2014 Universidad de Valparaiso. All rights reserved