A Light and Electron Microscope Survey of Algal Cell Walls. II, Chlorophyceae

Author Institution: Department of Botany, University of South FloridaUnder the light and electron microscopes, the structure of the cell walls of members of the 11 orders in the Class Chlorophyceae, Division Chlorophyta, were examined. With regard to the microfibrillar component of the cell walls, five types of wall structure were distinguished: (A) an apparent lack of a micro fibrillar component (Volvocales, Dasycladales, and some members of the Siphonales), (B) the microfibrils are arranged in a reticulate pattern (Tetrasporales, Schizogoniales), (C) the microfibrils are oriented in an axial direction (Ulotrichales, Oedogoniales, Zygnematales, and some members of the Siphonales), (D) the microfibrils are parallel to one another and arranged in lamellae (Ulvales), and (E) the microfibrils are parallel to one another, arranged in lamellae, and at right angles to the microfibrils in the lamellae above and below forming the crossfibrillar pattern (Cladophorales, Siphonocladales). Members of the Ulvales were found to have a cell wall similar to that of the brown algae while a member of the Schizogoniales, Prasiola, was found to have a cell wall similar to that of the red algae. A discussion of the taxonomic implications of cell wall structure is included

A Land-Based Thalassia testudinum Nursery Near Tampa Bay, Florida

An experimental, land-based seagrass nursery, built near Tampa Bay, FL, produced cultivars of Thalassia testudinum Banks and Solander ex König (turtle grass). The nursery was a rectangular basin measuring 6.1 X 12.2 m that graded from 1.5 to 2.0 m in depth constructed inside a fiberglass-covered pole building. The basin had a vinyl liner covered with 10–20 cm of sand and 1.0–1.3 m of water. The nursery ran for 26 mo and focused on producing cultivars of T. testudinum using differing planting techniques. Survival rates were 84% after 3–12 mo in the first planting and 91% after 4 mo in the second planting because early harvesting was required as a result of leaks in the vinyl liner. The planting method that resulted in the highest survival rate was bare rhizomes with two or more short shoots. The cultivars from the two nursery experiments were used in two mitigation projects in Tampa Bay. The nonrecurring cost of the nursery was $12,081.45 over a 3-yr period, and recurring costs are estimated at$22,280.00, with a potential production of 2,500 turf-like 20-cm2 units of T. testudinum that could be sold at $20.00 per planting unit

Seasonal Studies of Florida Sublittoral Marine Algae

The seasonal occurrence and reproduction of the sublittoral seaweed populations at four Florida sites are described. A total of 180 taxa were collected, including 105 Rhodophyceae, 49 Chlorophyceae, and 26 Phaeophyceae. The two southern sites in the Florida Keys showed higher numbers of species than the two northern sites off the central West Coast of Florida. The red algae were the most diverse group at each site. Green algae were more numerous than brown algae at the two Florida Key sites. Several of the species recorded represent extensions of known distributional ranges. Peak numbers of species were recorded during the winter-spring, when maximum nutrients and low temperatures were apparent. The station with the widest temperature fluctuation showed the most dramatic seasonality. The monthly occurrence and reproduction of each seaweed at the four sites are summarized

Photosynthetic responses of Florida seaweeds to light and temperature: a physiological survey

The photosynthetic responses of 37 tropical seaweeds (14 Chlorophyceae, 5 Phaeophyceae and 18 Rhodophyceae) were measured in a Gilson Warburg Apparatus under a variety of light and temperature regimes. The brown algae Padina vickersiae and Sporochnus pedunculatus exhibited the lowest saturation light intensity (263 μE/m2/sec), while five green algae (Acetabularia crenulata, Cladophora coelothrix, Dictyosphaeria cavernosa, Monostroma oxyspermum and Codium repens) had the highest light optima (3,843–4,258 μE/m2/sec). Overall, the Chlorophyceae exhibited the broadest range of light optima; in contrast, the Phaeophyceae primarily had low light optima, while several Rhodophyceae had higher light optima. The thermal optima for 34 seaweeds ranged from 15–30°C. Catoglossa leprierii, Botryocladia occidentalis, Codium taylorii, Soliera tenera and Codium intertextum exhibited relatively broad thermal optima, with C. leprierii having the most eurythermal response. The Chlorophyceae exhibited thermal optima between 15–30°C, the Phaeophyceae between 15–27°C, and most Rhodophyceae between 18–24°C. Few taxa, except for Cladophora coelothrix and Dictyosphaeria cavernosa, had broad physiological tolerances to both high temperature and light regimes. Overall, the Phaeophyceae exhibited the most restricted temperature and light optima, while the Chlorophyceae and Rhodophyceae exhibited broader tolerances

Distribution, morphology, and genetic affinities of dwarf embedded Fucus populations from the Northwest Atlantic Ocean

Dwarf embedded Fucus populations in the Northwest Atlantic Ocean are restricted to the upper intertidal zone in sandy salt marsh environments; they lack holdfasts and are from attached parental populations of F. spiralis or F. spiralis x F. vesiculosus hybrids after breakage and entanglement with halophytic marsh grasses. Dwarf forms are dichotomously branched, flat, and have a mean overall length and width of 20.3 and 1.3 mm, respectively. Thus, they are longer than Irish (mean 9.3 mm) and Alaskan (mean 15.0 mm) populations identified as F cottonii. Reciprocal transplants of different Fucus taxa in a Maine salt marsh confirm that F spiralis can become transformed into dwarf embedded thalli within the high intertidal zone, while the latter can grow into F. s. ecad lutarius within the mid intertidal zone. Thus, vertical transplantation can modify fucoid morphology and result in varying ecads. Microsatellite markers indicate that attached F spiralis and F vesiculosus are genetically distinct, while dwarf forms may arise via hybridization between the two taxa. The ratio of intermediate to species-specific-genotypes decreased with larger thalli. Also, F s. ecad lutarius consists of a mixture of intermediate and pure genotypes, while dwarf thalli show a greater frequency of hybrids

Contributions to the marine algae of Newfoundland

Volume: 71Start Page: 110End Page: 15

The Asian red seaweed Grateloupia turuturu (Rhodophyta) invades the Gulf of Maine

We report the invasion of the Gulf of Maine, in the northwest Atlantic Ocean, by the largest red seaweed in the world, the Asian Grateloupia turuturu. First detected in 1994 in Narragansett Bay, Rhode Island, south of Cape Cod, this alga had expanded its range in the following years only over to Long Island and into Long Island Sound. In July 2007 we found Grateloupia in the Cape Cod Canal and as far north (east) as Boston, Massachusetts, establishing its presence in the Gulf of Maine. Grateloupia can be invasive and may be capable of disrupting low intertidal and shallow subtidal seaweeds. The plant\u27s broad physiological tolerances suggest that it will be able to expand possibly as far north as the Bay of Fundy. We predict its continued spread in North America and around the world, noting that its arrival in the major international port of Boston may now launch G. turuturu on to new global shipping corridors

Southern expansion of the brown alga Colpomenia peregrina Sauvageau (Scytosiphonales) in the Northwest Atlantic Ocean

Blackler first recorded Colpomenia peregrina in the Northwest Atlantic based on collections from Nova Scotia, Canada. Five decades later we found large quantities of C. peregrina in Maine, USA, even though it was absent during earlier floristic studies in this region. Thus, C. peregrina has undergone a rapid southern expansion along the Northwest Atlantic coast. While the causes of such an expansion are unknown, it could have a major effect on both shellfish cultivation and native seaweeds within New England because of competitive interactions and increased drag