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In the past 15 years, scientific focus on the marine flora of the Northwestern Hawaiian Islands (NWHI) has intensified, resulting in a doubling of the total number of known species. In 1989, 205 species were recorded; as of January 2005, 353 species have been published for the NWHI. Over 5,100 specimens collected from Midway Atoll and other atolls, reefs, islands, and deep-water sites in the NWHI have shown a marine flora with geographic distribution patterns different from any known similar- sized area in the Pacific. Several new species of macroalgae have been described, including Dudresnaya babbittiana (Rhodophyta), Kallymenia thompsonii (Rhodophyta), Hydroclathrus tumulis (Phaeophyta), Padina moffittiana (Phaeophyta), and Codium hawaiiense (Chlorophyta). Since 1989, numerous macroalgal and two seagrass species have been documented as records of species new to the NWHI, including Kallymenia sessilis, Desmarestia ligulata, Nereia intricata, Sporochnus moorei, Caulerpa antoensis, C. cupressoides, C. elongata, C. microphysa, Halophila decipiens, and H. hawaiiana. Although the Hawaiian Archipelago is considered part of the Tropical Indo-West Pacific phytogeographic region, the NWHI's mixture of tropical species, cold-temperate species, species with disjunct distributions, and endemic species suggests alternative biogeographic patterns and dispersal routes.

Classic marine ecological paradigms view kelp forests as inherently temperate-boreal phenomena replaced by coral reefs in tropical waters. These paradigms hinge on the notion that tropical surface waters are too warm and nutrient-depleted to support kelp productivity and survival. We present a synthetic oceanographic and ecophysiological model that accurately identifies all known kelp populations and, by using the same criteria, predicts the existence of >23,500 km2 unexplored submerged (30- to 200-m depth) tropical kelp habitats. Predicted tropical kelp habitats were most probable in regions where bathymetry and upwelling resulted in mixed-layer shoaling above the depth of minimum annual irradiance dose for kelp survival. Using model predictions, we discovered extensive new deep-water Eisenia galapagensis populations in the Gala´pagos that increased in abundance with increasing depth to >60 m, complete with cold-water flora and fauna of temperate affinities. The predictability of deep-water kelp habitat and the discovery of expansive deep-water Gala´pagos kelp forests validate the extent of deep-water tropical kelp refugia, with potential implications for regional productivity and biodiversity, tropical food web ecology, and understanding of the resilience of tropical marine systems to climate change.

Distributions of dissolved nutrients and particulate matter downstream from a ma- rine fish farm at the Norwegian coast were examined. The samples were taken on transects from 25 m to 215 m distance to a specific fish cage. The samplings were carried out repeatedly while there was fish in that cage and once, after the fish were taken out. The outflow from a fish cage was estimated and a time series of current velocities was recorded downstream from a fish farm. The concentrations of nitrate, nitrite and phosphate were at very low levels and did not reveal any dependence on the distance to the fish cages. An influence of the fish farm on nutrient levels was only visible in the ammonia concentrations, which ranged around 15 μg NH4-N · l−1 on average and showed heavy fluctuations along the transects. Seaweed profits from higher ammonia concentrations in general, but enhanced growth in the study area would be limited by phosphate. On average, the concentrations of total particulate matter and particulate organic matter were at low levels, but showed an increase from 20.04.2005 to 02.06.2005 and a decrease after the fish were taken out of the net cage. This may have reasons other than the clearance of the fish cage, as an effect of the discharge from the cage on the concentrations of particulate matter within more than 50-60 m distance is highly unlikely. The fraction of organic matter was on high levels around 80% throughout the whole period of the study and did not show any dependence on the distance to the fish farm. Structures were found in the wake of a fish farm, that indicate the existence of eddies or swirls in the flow. It is very likely, that a vortex street develops downstream of a net cage, which would be associated with a recirculation area close to the cage. Such a wake characteristic might suppress the horizontal spreading of particles leaving the cage. A net outflow out of a fish cage was found from 3-23 m depth, which indicates the existence of some internal force. This might well be generated by fish swimming in circles. Fish behaviour, therefore, might play a role in the spreading of particles, as already small changes in the strength of the outflow might change the characteristics of the wake flow. 

Increased frequency and enhanced damage to the marine environment and to human society caused by green macroalgae blooms demand improved high-resolution early detection methods. Conventional satellite remote sensing methods via spectra radiometers do not work in cloud-covered areas, and therefore cannot meet these demands for operational applications. We present a methodology for green macroalgae bloom detection based on RADARSAT-2 synthetic aperture radar (SAR) images. Green macroalgae patches exhibit different polarimetric characteristics compared to the open ocean surface, in both the amplitude and phase domains of SAR-measured complex radar backscatter returns. In this study, new index factors are defined which have opposite signs in green macroalgae-covered areas, compared to the open water surface. These index factors enable unsupervised detection from SAR images, providing a high-resolution new tool for detection of green macroalgae blooms, which can potentially contribute to a better understanding of the mechanisms related to outbreaks of green macroalgae blooms in coastal areas throughout the world ocean.