Ecology and morphological characterization of gametophyte and ‘Chantransia’ stages of Sirodotia huillensis (Batrachospermales, Rhodophyta) from a stream in central Mexico

Abstract

The morphology and phenology of Sirodotia huillensis was evaluated seasonally in a central Mexican firstorder calcareous stream. Water temperature was constant (24-25°C) and pH circumneutral to alkaline (6.7-7.9), and calcium and sulfates were the dominant ions. The gametophyte stages were characterized by the presence of a distinctive mucilaginous layer, a marked difference in phycocyanin to phycoerythrin ratio between female and male plants, and the presence of a carpogonia with a large trichogyne (>60 µm). Occasionally three capogonia were observed on a single basal cell. The 'Chantransia' stages were morphologically similar to those described for the other members of Batrachospermales. A remarkable observation was the formation of dome-shaped structures, consisting of prostrate filaments that are related with the development of new gametophytes. Chromosome numbers were n = 4 for fascicle cells, cortical filament cells and dome-shaped cells, and 2n = 8 for gonimoblast filament cells and 'Chantransia' stage filaments. Gametophytes and 'Chantransia' stages occurred in fast current velocities (60-170 cm/s) and shaded (33.1-121 µmol photons/m 2 /s) stream segments. The population fluctuated throughout the study period in terms of percentage cover and frequency: the 'Chantransia' stages were most abundant in the rainy season, whereas gametophytic plants had the highest frequency values during the dry season. These results were most likely a result of fluctuations in rainfall and related changes in current velocity. Some characteristics of this population can be viewed as probable adaptations to high current velocities: the mucilaginous layer around plants that reduces drag; potential increase in fertilization by the elongate and plentiful trichogynes and abundant dome-shaped structures producing several gametophytes.

Phenology of Sirodotia suecica (Batrachospermaceae, Rhodophyta) in a high‐altitude stream in central Mexico

“…1993; Kumano 2002). The studies of Pascoaloto and Necchi (1990), Necchi and Branco (1999), Necchi and Vis (2005) and Carmona et al. (2006) are the most comprehensive investigations of the reproductive success of each phase of the life‐history of Sirodotia species.…”

“…In contrast, dioecious populations of Sirodotia huillensis Welwitsch ex G.S. West et West are restricted to waters of low irradiance and high temperature, and exhibits a low female: male thallus ratio and a low number of carposporophytic thalli (Carmona et al. 2006).…”

Estudio Del Valor Indicador De Las Comunidades De Algas Bentónicas: Una Propuesta De Evaluación Y Aplicación en El Río Magdalena, Ciudad De México

“…Las observaciones se realizaron sobre sustratos naturales (rocas) directamente en el lecho del río. La abundancia de los crecimientos visibles fue calculada con la técnica de cuadrante (Necchi et al 1995, Necchi y Branco 1999, Carmona et al 2006) que estima la influencia de las variables a nivel microambiental (velocidad de la corriente y la profundidad) en el porcentaje de cobertura de las poblaciones. El sitio de muestreo consistió de un segmento del río de 10 m de longitud.…”

Phenology of Paralemanea mexicana (Batrachospermales, Rhodophyta) in a high‐altitude stream in central Mexico

“…); abundance of branches or dense growth forms can reduce drag force (Sheath & Hambrook ); and presence of large amounts of mucilage surrounding the thallus (Carmona et al . ). As reproductive adaptations are somatic meiosis, clonal multiplication in the ‘Chantransia’ stage (Sheath ; Necchi & Carmona ) and abundant spermatangia and carposporangia small in size (Carmona et al .…”

“…The red algal orders Batrachospermales is a conspicuous group of freshwater Rhodophyta that occurs widely in lotic ecosystems throughout the world (Sheath & Hambrook 1990) and appear to be highly specialized to these ecosystems. Batrachospermalean taxa have several morphological and reproductive adaptations that could be linked to unidirectional current velocity For example, morphological adaptation related with the formation of rhizoidal filaments, or aggregation of filaments, from which an efficient attachment system is produced (Carmona et al 2009); abundance of branches or dense growth forms can reduce drag force (Sheath & Hambrook 1990); and presence of large amounts of mucilage surrounding the thallus (Carmona et al 2006). As reproductive adaptations are somatic meiosis, clonal multiplication in the 'Chantransia' stage (Sheath 1984;) and abundant spermatangia and carposporangia small in size (Carmona et al 2009).…”