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

An Empirical Exploration of Exchange Rate Target-Zones

In the context of a flexible-price monetary exchange rate model and the assumption of uncovered interest parity, we obtain a measure of the fundamental determinant of exchange rates. Daily data for the European Monetary System are used to explore the importance of non-linearities in the relationship between the exchange rates and fundamentals. Many implications of existing "target-zone" exchange rate models are tested; little support is found for existing non-linear models of limited exchange rate flexibility.

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

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