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As a possible means of improving the livelihoods of local villagers, off-bottom rope cultivation of commercial eucheumoids was investigated on the southern Kenyan coast at three sites, representative of the variety of environments. The morphotypes used were brown and green and brown . The study was carried out over a 15 month period from August 2001 until October 2002. Relative growth rates were highest at a sandy flat in a mangrove system (Gazi; 5.6% d), and lowest in an intertidal reef flat (Kibuyuni; 3.2% d) with a lagoon being intermediate (Mkwiro; 4.8% d). The brown had the highest growth rate of 4.7% d compared to the green and brown which were 4.3% d and 4.2% d, respectively. Growth was more variable at Kibuyuni and Mkwiro. The growth was higher during the southeast monsoon (4.7% d) than during the northeast monsoon (4.0% d). This is part of a larger study and the effects of water motion, salinity, temperature, thallus nitrogen, and ‘ice-ice’ syndrome on growth of morphotypes is discussed. The water motion was observed to increase thallus nitrogen and hence the growth of eucheumoids. The ‘ice-ice’ condition affected both brown and brown but not green . The results suggest that commercial cultivation of eucheumoids in Kenya will be feasible.

is an ecologically dominant species along the temperate Northern and Southern Pacific Coast of America, showing some similarities and differences at population and community level. In general, this kelp is reported to be reproductive all year round. Annual populations present in wave-protected areas of southern Chile suggest that the reproductive strategies of this population can be different. In this study we explore the reproductive strategies of annual present in wave-protected areas and perennial populations encountered in exposed areas of southern Chile (41°S). Our results showthat present in wave-exposed locations has a reproductive strategy that is similar to populations in the northern hemisphere. These populations reproduce all year round and their strategy is to produce high numbers of sporophylls and ensure that most of them (over 90%) become sporogenous. On the other hand, the protected populations with an annual life cycle, produce more spores per area of sorus. In a few months, they are able to produce sufficient propagules to recolonize areas before the adult plants disappear in autumn.

Several phycocolloid-producing Rhodophyta of significant economic importance are coalescing species, able to fuse with conspecifics during recruitment, reach larger sizes and increase their survival. In these species spores are needed to start cultivation (e.g. ) or to increase the seed stocks, to renew senescent clones or to enlarge the base of genetic variation of vegetatively propagated species (e.g. ). This study uses to evaluate some key features that influence recruitment success. Field measurements indicate that in any recruitment event a variable amount of the spores reaching a given place may form groups of 2 to over 100 coalescing spores, while field experiments support the idea that early recruitment success is a function of the number of coalescing spores forming the individual, as multisporic, coalescing recruits have higher survival rates than sporelings formed by one or a few spores. Therefore, group recruitment (spores settling and recruiting in close spatial proximity) appears as a prerequisite for sporeling coalescence and early recruitment success. In turn, laboratory experiments suggest that the frequency of group recruitment and coalescence increases with increasing spore abundance and with slight Ca additions to the culture medium. These last two factors could be handled by farmers to improve the success of spore inoculations of coalescing species.

The distribution and recent reduction of beds, i.e. mat-like beds dominated by the agarophyte Kützing in Toyama Bay (Sea of Japan), in which 95% of the coastline is protected artificially, are reported. beds were common in shallow waters (usually <10m deep); most of the large beds (>1 ha) were restricted to the inner coasts of the bay. In calm and eutrophic areas, however, was heavily colonized by epiphytes. In the last decade, two beds were buried and beds in their vicinity were damaged by the stagnation of coastal water and/or sedimentation by silts which accompanied land reclamation. At the other two beds monitored since 1988, declined a few times but most prominently in 1998, when episodic long summer rain was recorded. This is the first report, not only on the current status of beds other than for the central Pacific Coast of Honshu in Japan, but also concerning reduction of the beds caused by both anthropogenic and natural events.

The aim of this study was to better understand the down-grazing of kelp beds by sea urchins () along the coast of Norway. Barren grounds were first observed in sheltered areas along the coast of the counties of Trøndelag, Nordland and Troms in 1974. In the 1980s, the barren grounds spread to areas more heavily exposed to waves. In the 1990s, the kelp beds were re-established in some localities in southern Trøndelag, initially in wave-exposed areas. In the northernmost parts of Norway, i.e. the counties of Troms and Finnmark, the barren ground areas may still be increasing. Crabs () and common eiders are the most common predators on urchins. Predation on sea urchins in kelp beds is probably not among the factors that limit the sea urchin populations. Along the coast of Nordland and further north, sea urchins are infected by nematodes, resulting in a low, but significant increase in their mortality. No re-growth of kelp beds has been found in the most infected areas. In the late 1960s and the early 1970s, a high occurrence of echinoderm larvae was observed in deeper waters. This was a period with cold water, which may have caused high recruitment of sea urchins. The bet-hedging life strategy of sea urchins may account for the sudden increase in the size of the populations. In the present paper I propose the hypothesis that higher individual growth rates and higher mortality rates in the south than in the north may explain the decrease in the populations, which may in turn account for the re-growth of kelp in the southern areas.

Common problems faced in farming of the red algal genus are “ice-ice disease” and the occurrence of epiphytes. Considerable work has been documented on “ice-ice disease” and it’s mode of infection but limited information is available on the emergence of epiphytes. The present study addresses the phenomenon of epiphyte infection, its prevalence in commercially cultivated red alga, , and their variability associated with seasonality. Cultured seaweed became susceptible to epiphytes in the dry seasons (1) between March – June and (2) September – November. Findings revealed (Hariot) M. S. Kim I. K. Lee, as the dominant infecting epiphyte, representing up to 80–85% of the epiphyte present during peak seasons. Besides sp., sp. and sp. were observed in smaller quantities. SEM (Scanning Electron Microscope) micrographs revealed the epiphyte’s attachment to the host. Further histological study showed the extent of penetration of epiphytes into the host’s cortex tissues and condition of its surrounding tissues. The outbreak of epiphytic filamentous red algae also correlated with drastic changes in seawater temperature and salinity during March – June and September – November.

Kalk Bay, South Africa, has a typical south coast zonation pattern with a band of seaweed dominating the mid-eulittoral and between two molluscan-herbivore dominated upper and lower eulittoral zones. Encrusting coralline algae were very obvious features of these zones. The most abundant herbivores in the upper eulittoral were the limpet, (10.4±1.6 individuals m; 201.65±32.68 g.m) and the false limpet, (97.07±19.92 individuals m; 77.93 16.02 g.m). The territorial gardening limpet, , dominated the lower eulittoral zone, achieving very high densities (545.27±84.35 m) and biomass (4630.17±556.13 g.m), and excluded all other herbivores and most seaweeds, except for its garden alga and the encrusting coralline alga, (35.93±2.26% cover). In the upper eulittoral zone, encrusting coralline algae were only present in the guts of the chiton (30.5±1.33%) and the limpet (2.9±0.34%). The lower eulittoral zone limpet, also had a large percentage of encrusting coralline algae in its gut with limpets lacking gardens having higher (45.1±1.68%) proportions of coralline algae in their guts than those with gardens (25.6±0.8%). Encrusting coralline algae had high organic contents, similar to those of other encrusting and turf-forming algae, but higher organic contents than foliose algae. Radula structure, grazing frequencies as a percentage of the area grazed (upper eulittoral 73.25±3.60% d; lower eulittoral 46.0±3.29% d), and algal organic content provided evidence to support the dietary habits of the above herbivores. The data show that many intertidal molluscs are actively consuming encrusting coralline algae and that these seaweeds should be seen as an important food source.

Eight species of the brown alga have been recorded from Tung Ping Chau Marine Park in Hong Kong and the phenology of four of these was monitored from 1996 to 2000. All four species followed a typical growth cycle of species reported elsewhere but with some annual variations. For , the maximum mean (±SD) plant length, ranging from 38.5 ± 10.5 to 61.9 ± 19.9 cm, was recorded in January to March. The peak reproductive season was also mainly in February to March with up to 89% of the plants being reproductive. Some plants, however, remained reproductive until May. For. , the maximum mean plant length, ranging from 45.5 ± 25.5 to 77 ± 24.8 cm, was recorded mainly in November to January. The peak reproductive season was in November to February with up to 100% of the plants being reproductive. For , the maximum mean plant length, ranging from 48.2 ± 29.9 to 63.4 ± 22.1 cm, was also recorded mainly in January. The reproductive plants were found mainly between late December and mid February with up to 98% of the plants being reproductive. For. , the maximum mean plant length ranging from 87.6 ± 62.4 to 118.7 ± 41.3 cm was recorded in January to March. Reproduction of this species was not monitored. Changes in water temperature over seasons were likely to be critical in affecting the phenological patterns of these species.

A recent survey of seaweed specimens collected in Alaska over the past two centuries, together with the application of molecular techniques to recent collections, has revealed a surprisingly diverse flora given the history of glaciation, large areas of unsuitable habitat, and otherwise harsh environmental conditions. The number of recognized species has increased from 376 in 1977 to about 550 today. Species show a variety of biogeographic patterns: species that occur primarily to the south and have their northern limit in Alaska, species that occur primarily to the west and have their eastern limit in Alaska, species that are primarily Atlantic but extend through the Arctic to Alaska, and a number of endemics. Within these broad distribution patterns are more localized patterns often involving disjunctions. These disjunctions, the occurrence of endemic species, patterns of genotype distributions, and the overall richness of the seaweed flora support the idea that marine refugia must have existed in Alaska during Pleistocene glaciations.

The systematics and taxonomy of and (Solieriaceae) is confused and difficult due to morphological plasticity, lack of adequate characters to identify species and commercial names of convenience. These taxa are geographically widely dispersed through cultivation. Commercial, wild and herbarium sources were analysed; molecular markers provided insights into taxonomy and genetic variation, and where sources of genetic variation may be located. The mitochondrial 2–3 and plastidal RuBisCo spacers were sequenced. There is a clear genetic distinction between (“cottonii”) and (“sacol”) samples. from Hawaii and some samples from Africa are also genetically distinct. Our data also show that all currently cultivated from all over the world have a similar mitochondrial haplotype. Within (“spinosum”) most African samples are again genetically distinct. Our data also suggest that currently cultivated may have been “domesticated” several times, whereas this is not evident for the cultivated . The present markers used do not distinguish all the morpho-types known in cultivation (e.g. var. , “giant” type) but do suggest that these markers may be useful to assess introductions and species identification in samples.