Biosystematics, genetics and upper temperature tolerance ofGigartina teedii (Rhodophyta) from the Atlantic and Mediterranean

The deep-water macroalgal community of the continental shelf off the east coast of Florida was sampled by lock-out divers from two research submersibles as part of the most detailed year-round study of a macroalgal community extending below routine SCUBA depths. A total of 208 taxa (excluding crustose corallines) were recorded; of these, 42 (20.2 %), 19 (9.1%), and 147 (70.7 %) belonged to the Chlorophyta, Phaeophyta, and Rhodophyta, respectively. Taxonomic diversity was maximal during late spring and summer and minimal during late fall and winter. The number of reproductive taxa closely followed the number of taxa present; when reproductive frequency was expressed as a percentage of the species present during each month, two peaks (January and August) were observed. Most perennial species had considerable depth ranges, with the greatest number of taxa observed from 31 to 40 m in depth. Although most of the taxa present also grow in shallow water (i.e. <10 m), there were some species whose distribution is hmited to deeper water. The latter are strongly dominated by rhodophytes. This community has a strong tropical affinity, but over half the taxa occur in warm-temperate areas. Forty-two new records (20% of the taxa identified) for Florida were listed; this includes 15 taxa whicl~ previously had been considered distributional disjuncts in this area. The phaeophyte Halopteris filicina is a new addition to the flora of the western Atlantic. Although more studies are needed, it appears that the deep-water flora may be relatively continuous over a large portion of the tropical and subtropical western North Atlantic. The traditional practice of considering Cape Canaveral as a biogeographical boundary may only be appropriate for shallow water. This study demonstrates the need for additional floristic work on macroalgal communities, especially from deep water, before more detailed biogeographical analyses can be performed and suggests that deep-water species could be important in experimental approaches to macroalgal biogeography.

Section: Discussionmentioning

confidence: 99%

The deep-water macroalgal community of the East Florida continental shelf (USA)

Hanisak

Blair

1988

“…Fortes & Lfining, 1980;Bolton, 1983;Guiry et al, 1987;Wiencke & tom Dieck, 1989, although some investigations used experimental periods of up to seven months (Rueness & Tanager, 1984;Yarish et al, 1986). In the current study, growth rates were determined weekly or fortnightly over 5 (or 6) weeks (Fig.…”

Section: Methodological Considerationsmentioning

confidence: 99%

Temperature requirements for growth and survival of macroalgae from Disko Island (Greenland)

Bischoff

Wiencke

1993

The temperature requirements for growth and upper temperature tolerance were determined in 16 macroalgal species collected on Disko Island (Greenland). The upper survival temperatures were examined in 1 ~ steps, and growth measured at 5~ intervals between 0 and 20 ~ using a refined method, where the fresh weight was determined weekly or fOrtnightly over a period of 5 or 6 weeks. To express temperature-growth responses, growth rates of temperatureacclimated plants were taken. Two groups with different temperature requirements were identified: The upper survival temperatures in these species and inChaetomorpha tortuosa, Bangia atropurpurea and Eudesme virescens were between 24 and 31 ~ These algal species showed little adaptation to the Arctic temperatures. In contrast, algae from the first group exhibited a relatively high adaptation to low temperatures -approaching the low temperature requirements of Antarctic algae. The results are discussed in relation to the geographic distribution of individual species.

“…;BoRon & Luning, 1982;Guiry et al, 1987;Breeman, 1988), even in cases where there are variations in the thermal response with respect to reproduction (Novaczek, 1984), morphogenesis (tom Dieck, 1987;Rietema & van den Hoek, 1984) or growth (see refs. in Breeman, 1988).…”

Section: Discussionmentioning

confidence: 97%

“…When they do occur, variations in upper lethal limits are only of 1-3~ (Novaczek & Breeman, unpubl, obs. ;Lfining et al, 1987;Breeman, 1988;Gerard & DuBois, 1988). One apparent anomaly isthe case of the cosmopolitan "species"…”

Section: Discussionmentioning

confidence: 98%

Thermal tolerance ofStypocaulon scoparium (Phaeophyta, Sphacelariales) from eastern and western shores of the North Atlantic Ocean

Novaczek¹,

Breeman²,

Hoek³

1989

Isolates of Stypocaulon scoparium Kfitz. were collected from the Gulf of St. Lawrence, Canada and compared in culture to isolates collected from the Atlantic and Mediterranean coasts of Europe. The Canadian isolates grew at temperatures ranging from -2 ~ up to 22 ~ with maximum rates of growth at 10-15 ~ in trials lasting 3 months they survived the lowest temperatures but died at 22 or 25 ~ In contrast, for the European isolates, maximum growth occurred between 10 and 27 ~ and they died only after several months at 30 or 33 ~ At the low end of the temperature range, European plants suffered damage or died at 5~ Only the northernmost isolate, from Brittany, could both survive at 0~ and remain undamaged at 5~ in short days. All European isolates died at -2 ~ Geographic distributions and the different thermal responses suggest that the eastern and western Atlantic populations are two different entities, the European plants being possibly of Tethyan origin, and the Canadian plants being possibly of north Pacific origin. The former would then have occupied the north Atlantic for the longest time, which may partly explain the occurrence of ecotypic variation among these isolates.