Growth and Fertility, in Relation to Temperature and Photoperiod, in South African Desmarestia firma (Phaeophyceae)

Abstract

The influence of temperature on growth of young sporophytes, and the effects of temperature and photoperiod on growth and fertility of gametophytes, have been investigated in laboratory culture in South African endemic Desmarestia firma. Young sporophytes grew best between 8 and 19°C (optimum 12°C), growth at 4 and 22 °C was slow, and they died at 26 °C Gametophytes, under both long-day (LD) and short-day (SD) conditions, grew best at temperatures between 12 and 18 °C (optimum 15 °C), growth at 4, 8, and 22 °C was slow, and they died at 26 °C. Short-day conditions were required to initiate fertility in the gametophytes, fertility rates were higher at 8 °C than at 12 and 15 °C, and none became fertile at 17 °C. The highest rates of fertility were obtained in gametophytes grown under LD conditions at 15 °C and then transferred to SD at 4 °C. Seasonal sea temperatures on the southern African coast indicate that the eastern boundary for this species is set by the effect of high summer temperatures on the sporophyte, while the northern limit might be set by the effects of either high summer or winter temperatures, on the sporophytes or gametophytes respectively. The distribution of branched, ligulate Desmarestia species worldwide is discussed in relation to our results and those from other studies.

Temperature tolerance and survival in darkness of kelp gametophyles (Laminariales, Phaeophyta): ecological and biogeographical implications

“…The closely related order Desmarestiales spans at least 15°C in UST for the gametophytes. Gametophytes of Antarctic Desmarestia anceps, D. menziesii, Phaeurus antarcticus and Himanthothallus yrandifolius survived 13, 16 to 17, 15 to 16 and 15 to 16°C respectively (Wiencke & tom Dieck 1989) and gametophytes of cold-temperate South African D. firma survived 22 to < 26 "C (Anderson & Bolton 1989). Eleven South American and northern hemisphere Desmarestia species were tested with upper survival limits of gametophytes between 21.8 and 28.5"C (Peters & Breeman 1992.…”

“…Eleven South American and northern hemisphere Desmarestia species were tested with upper survival limits of gametophytes between 21.8 and 28.5"C (Peters & Breeman 1992. Considering the distribution of the genus Desmarestia (Anderson & Bolton 1989, Liining 1990, it is not expected that this range will increase by much even if more species were tested. Comparison with other algal orders is difficult due to insufficient data.…”

Growth of red and green strains of the tropical agarophyte Gracilaria cornea J. Agardh (Gracilariales, Rhodophyta) in laboratory

“…The absence of reproductive structures during the experimental period could be a result of a possible excess of nutrients, although other factors might also affect reproduction, such as temperature, salinity, photoperiod or irradiance (Guiry 1984, Graham et al 1985, Anderson & Bolton 1989, Hoffmann & Malbrán 1989. Gametophytes of G. cornea have been cultivated in our laboratory for several years and, up to now, they have not become fertile, differently from other "gracilarioid species" (Plastino & Oliveira 1988ae b, Guimarães et al 1999, Costa & Plastino 2001.…”

The Role of Alternate Life-History Stages of a Marine Macroalga: A Seed Bank Analogue?

“…Unlike the seeds of terrestrial plants (Venable and Lawlor 1980, Keeley 1987, Alvarez-Buylla and Martínez-Ramos 1990, Pake and Venable 1996, or the resting stages of marine copepods (Grice and Marcus 1981, De Stasio 1989, Maier 1990, Viitasalo 1992, diatoms (Hollibaugh et al 1981), and insects (Tauber and Tauber 1978), laboratory studies on marine macroalgae indicate their microscopic stages remain physiologically active under light and temperature conditions that are unfavorable to the macroscopic stages (Kain 1964, Anderson and North 1969, Shreader and Moss 1975, Fain and Murray 1982, Nakahara 1984, Anderson and Bolton 1989, Santelices et al 1995. This is true for Desmarestia; gametophytes were not dormant while they overwintered, but rather were metabolically active and thus sensitive to changes in environmental quality.…”