Seaweed Flora Research Articles

The first record of a non-native seaweed from South Georgia and confirmation of its establishment in the Falkland Islands: Ulva fenestrata Postels & Ruprecht

Detecting non-native species can be challenging, particularly in the case of taxa such as seaweeds, which can be difficult to distinguish based on morphology and often require molecular-assisted taxonomy for reliable identification. The sub-Antarctic island of South Georgia supports unique and important marine biodiversity, including a rich seaweed flora, but despite its isolation, its inshore ecosystems are susceptible to the introduction of potentially invasive non-native species. Here, we provide the first report of a non-native seaweed in South Georgia, Ulva fenestrata Postels & Ruprecht (Ulvophyceae, Chlorophyta), and confirm its widespread presence in the Falkland Islands via molecular-assisted taxonomy. Phylogenetic analyses of tufA and rbcL-3P genetic markers enabled the identification of a specimen collected from Grytviken, South Georgia in November 2021 as U. fenestrata. In terms of tufA sequence, this sample was identical to specimens collected from four sites spanning West and East Falkland in 2013 and 2018. This study represents the second Southern Hemisphere record of U. fenestrata, which is generally regarded as a Northern Hemisphere species. Our findings provide a foundation for monitoring this potentially invasive species in South Georgia, and for determining its likely source and mode of arrival, while emphasising the importance of robust biosecurity measures.

Marine Benthic Algae of the Eastern Samar Islands of Homonhon, Sulu-an, and Manicani, Philippines

Botanical explorations in the Philippines have been conducted for the most part in easily accessible regions, resulting in fragmentary information that prevents a thorough assessment of its total biological richness. Many insular sites, which are potentially biologically diverse, remain unexplored due to reasons of geographic isolation, weather disturbance, and logistical considerations. To address these gaps and to provide added information on the diversity and distribution of the seaweed flora around the archipelago, we report herein the taxonomy of the marine benthic algae of three islands in Eastern Samar province. Macrobenthic algae were collected in 18 sites in Homonhon, Sulu-an, and Manicani islands in Guiuan. Seaweeds were identified in situ up to the lowest taxonomic level possible and further analyzed in the laboratory. Cluster analysis based on the Jaccard index using the PAST software was used to infer similarities among the sampling sites with respect to the seaweed flora of the newly collected samples. Analysis of similarities and similarity percentage were also used to further support the results of the study. The paper highlights 56 seaweeds (Chlorophyceae: 28 spp.; Phaeophyceae: 11 spp.; Rhodophyceae: 17 spp.) collected in 18 collection sites in Homonhon, Manicani, and Sulu-an Islands in Guiuan, Eastern Samar. All are considered new records to the small islands, whereas 39 are considered new records of species in the Eastern Samar province. Cluster analysis suggests similarities in seaweed flora in the islands, which may be attributed to the substrates and hydrodynamism in the islands. The islands have a relatively diverse seaweed flora, despite its narrow areas highlighting 5% of the total seaweed flora of the country. This paper is the first attempt to provide better documentation of macroalgal communities in remote islands in the Eastern Philippines (Guiuan, Eastern Samar).

Nuclear DNA content estimations and nuclear development patterns in Antarctic macroalgae

Nuclear DNA content of marine macroalgae is known for only about a 3% of the globally known taxa, and so far, the only available data concerning marine Antarctic macroalgae refer to the Phaeophyceae Ascoseira mirabilis and Desmarestia antarctica. As these data can be useful for species delimitation when combined with other taxonomical information, we aimed to expand the available number of measurements in the understudied Antarctic seaweed flora. To address this, we measured the nuclear DNA content of 12 Antarctic marine algae (seven Rhodophyceae and five Phaeophyceae). Nuclear DNA analyses were carried out by spectrofluorimetry and image analysis from samples conserved in Carnoy, using DAPI as DNA marker. For ten of these taxa, our values represent the first estimations to date. The nuclear DNA content estimates obtained for the Antarctic red algae examined vary between 2C = 0.38 pg in Gigartina skottsbergii and 2C = 1.63 pg in Neuroglossum delesseriae. In brown algae, the values range from 2C = 0.18 pg in both Desmarestia antarctica and Desmarestia menziesii to 2C = 0.96 pg in Phaeurus antarcticus. Furthermore, this study allowed us to identify nuclear developmental patterns for the first time in two Antarctic seaweeds (Ballia callitricha and Neuroglossum delesseriae).

The seaweed resources of Ireland: a twenty-first century perspective

The harvesting of wild seaweeds continues to play an important cultural and socioeconomic role for many coastal communities on Ireland’s Atlantic seaboard. Although Irish waters contain a diverse and substantial benthic seaweed flora, only a few species are exploited commercially. Historically in Ireland, seaweed was commercially used as a raw material in the production of high-volume, low-value commodities such as animal feed and raw material for alginate production. Recently, with increasing acceptance of seaweed as a sea vegetable and its ever-increasing role as a raw material in the cosmetic and pharmaceutical industries, there has been a renewed vigour in the Irish seaweed industry particularly with new entrants into the human nutrition and cosmetic markets producing high-quality, high-value products. Although many of Ireland’s native seaweed species can be sustainably exploited if well managed, the fucoid Ascophyllum nodosum maintained its prominent role in the Irish seaweed industry. The traditional harvesting of A. nodosum in Ireland continues, although the recent introduction of new harvesting techniques, along with the expected expansion of the Irish seaweed cultivation sector, undoubtedly marks a shift in the Irish seaweed seascape. We focus here on the seaweed resources in Irish waters and how the industry has changed in the last 20 years.

A new species of Polycoelia (Kallymeniaceae, Rhodophyta), P. kurariirapa, from the Three Kings Islands/Manawatāwhi, New Zealand

ABSTRACTA new species of Polycoelia, P. kurariirapa, is described from the Three Kings Islands/Manawatāwhi, representing the first record of the genus in New Zealand. Polycoelia includes two species from Australia, P. laciniata (generitype) and P. fastigiata, and one from South Africa, P. harveyana. Polycoelia kurariirapa shares with the two Australian species the characteristic vegetative anatomy of the genus consisting of a single layer of medullary cells surrounded by a cortex of small-celled, anticlinal filaments, and branched thalli. The rbcL phylogenetic analysis confirmed the close, and sister, relationship of P. kurariirapa with the Australian taxa, while they were only weakly grouped with P. harveyana. This new genus adds to the unique seaweed flora of these islands in northern New Zealand and indicates that this area may harbour even more hidden diversity.

Seaweed breeding programs and progress in eastern Asian countries

ABSTRACTThe use of seaweeds as human food in eastern Asian countries has a long history, stretching back over a thousand years. However, it was not until the late 1940s that cultivation of seaweeds in near-shore coastal areas began. Due to their location, the Korean peninsula, the Japanese islands and the Chinese coasts share a similar seaweed flora in their coastal waters, and it is not surprising that seaweed species chosen for cultivation, methods of farming and post-harvest processing in these countries have a lot in common. In 2016, the total seaweed production in these three countries reached 16,218,406 t, approximately 53.8% of global seaweed production (FAO). In the course of seaweed farming development in eastern Asia, the development and use of seaweed cultivars have contributed significantly to the seaweed farming industry in terms of improving both the biomass yield and the quality of the food products produced. In this article, the recent development of cultivar-related research and applications practised in Korea, Japan and China are reviewed with particular reference to the key commercial species: Saccharina japonica, Pyropia spp., Undaria spp., Cladosiphon okamurarus, and Nemacystus decipiens. In the past 21 years, 47 certified seaweed cultivars have been used in commercial cultivation in these countries. While much of the development effort has focused on increasing yields, a current emphasis in cultivar breeding programs is to increase the quality of farmed seaweed products. More recently, molecular analyses have been integrated into these programs and have become indispensable tools in the breeding process.

Sublittoral seaweed flora of the St. Martin’s Island, Bangladesh

Investigation on the sublittoral seaweed flora collected from 0.5 to 10 m depth during late March and April, 2013 from six localities around the St. Martin’s Island, Bangladesh has revealed the presence of 39 seaweed taxa, 12 under Rhodophyceae, 11 under Chlorophyceae and 16 under Phaeophyceae. Of these Avrainvillea amadelpha (Montagne) Gepp et Gepp (green), Pocockiella variegata (Lamx.) Papenfuss, Spatoglossum asperum J. Ag., Spatoglossum variabile Figari et De Notaris and Sargassum pallidum (Turner) C. Agardh (browns) are new records for Bangladesh.

Habitat‐forming seaweeds in Japan (fucoids and temperate kelps)

AbstractThis paper describes the flora of habitat‐forming seaweeds (fucoids and temperate kelps) at 7673 sites of the Japanese coast encompassing its warm to cold temperate zone, recorded from 1887 to 2014. The data set includes 86 species (21,168 presence and 20,845 absence records), compiled from 355 literature sources, most of which were written in Japanese and published as grey literature in local journals or individual reports. Scientific names were consolidated under currently‐accepted nomenclature based on Algaebase (http://www.algaebase.org). The data set compiled the seaweed flora at each study site each year, the geographical location and the scientific names. Additionally, three supporting data sets were created respectively including name of each site, synonyms of the seaweeds, and the corresponding literature list. This rich collection of data can be used to study the biogeography and long‐term changes of particular species and the diversity of habitat‐forming seaweeds of the Japanese coast.

한국 서해안 학암포 해조상 및 군집구조의 장기모니터링 연구

한국 서해안 학암포 해조상 및 군집구조의 장기모니터링 연구

SUBARCTIC RHODOLITH BEDS PROMOTE LONGEVITY OF CRUSTOSE CORALLINE ALGAL BUILDUPS AND THEIR CLIMATE ARCHIVING POTENTIAL

ABSTRACT The rocky, photic benthos of Arctic and Subarctic Biogeographic Regions has a characteristic seaweed flora that includes an extensive high-magnesium calcium carbonate basal layer of crustose coralline red algae. The thickest (10–40 cm) and oldest parts of the crust (previously reported as up to 640–830 years old), primarily at mid-photic depths of 15–25 m, are composed of buildups of the genus Clathromorphum. Due to its annual growth increments and cycling of Mg content with temperature, Clathromorphum has recently been developed as a high-resolution climate archive. The age of the archive is primarily limited by the boring of mollusks that reduce structural integrity, remove the record, and induce local diagenesis. Depressions and gentle slopes in the deeper portions of Subarctic rocky bottoms often collect mixed bioclastic and siliciclastic sediments, including a dense cover of rhodoliths (Lithothamnion glaciale and Lithothamnion tophiforme). In this paper we describe a transition zone of these...

European seaweeds under pressure: Consequences for communities and ecosystem functioning

Seaweed assemblages represent the dominant autotrophic biomass in many coastal environments, playing a central structural and functional role in several ecosystems. In Europe, seaweed assemblages are highly diverse systems. The combined seaweed flora of different European regions hold around 1550 species (belonging to nearly 500 genera), with new species continuously uncovered, thanks to the emergence of molecular tools. In this manuscript we review the effects of global and local stressors on European seaweeds, their communities, and ecosystem functioning. Following a brief review on the present knowledge on European seaweed diversity and distribution, and the role of seaweed communities in biodiversity and ecosystem functioning, we discuss the effects of biotic homogenization (invasive species) and global climate change (shifts in bioclimatic zones and ocean acidification) on the distribution of individual species and their effect on the structure and functioning of seaweed communities. The arrival of new introduced species (that already account for 5–10% of the European seaweeds) and the regional extirpation of native species resulting from oceans' climate change are creating new diversity scenarios with undetermined functional consequences. Anthropogenic local stressors create additional disruption often altering dramatically assemblage's structure. Hence, we discuss ecosystem level effects of such stressors like harvesting, trampling, habitat modification, overgrazing and eutrophication that impact coastal communities at local scales. Last, we conclude by highlighting significant knowledge gaps that need to be addressed to anticipate the combined effects of global and local stressors on seaweed communities. With physical and biological changes occurring at unexpected pace, marine phycologists should now integrate and join their research efforts to be able to contribute efficiently for the conservation and management of coastal systems.

Embryology of zygote and development of germling in Sargassum vachellianum Greville (Fucales, Phaeophyta)

Sargassum vachellianum Greville is one of the most important members in the subtidal seaweed flora along the coasts of the Eastern China Sea. In order to understand the embryology of zygotes and development of germlings in S. vachellianum, we performed artificial ripening, systematically observed the morphological changes and development of the fertilized eggs and germlings, and explored the effects of culture conditions on the growth of the germlings. The receptacles matured, and eggs and sperm were released after 1–5 days of culture at 21–24 °C under 60–90 μmol photons m−2 s−1 (14L:10D). Once fertilized, zygotes immediately detached from the female receptacles and began to germinate. Eight nuclei in the released fresh zygote soon begun to fuse, forming a large central nucleus, and underwent two horizontal divisions to produce a small “original rhizoid cell,” which eventually formed rhizoids after several divisions, and three other cells which eventually formed landmine-like germlings after several continuous divisions. The germlings then formed rhizoids and attached onto the bottom of the flask within 12 h of culture. The growth and development of the germlings younger than 20 days were significantly influenced by the culture temperature and light, with the optimal conditions being 21 °C and 40 μmol photons m−2 s−1. However, for germlings older than 30 days, the optimal conditions were 24 °C and 60 μmol photons m−2 s−1.

Checklist of the marine macroalgae of Vietnam

Abstract Despite a rich seaweed flora, information about Vietnamese seaweeds is scattered throughout a large number of often regional publications and, hence, difficult to access. This paper presents an up-to-date checklist of the marine macroalgae of Vietnam, compiled by means of an exhaustive bibliographical search and revision of taxon names. A total of 827 species are reported, of which the Rhodophyta show the highest species number (412 species), followed by the Chlorophyta (180 species), Phaeophyceae (147 species) and Cyanobacteria (88 species). This species richness is comparable to that of the Philippines and considerably higher than Taiwan, Thailand or Malaysia, which indicates that Vietnam possibly represents a diversity hotspot for macroalgae. A comparison of the species composition with neighbouring countries yielded surprisingly low similarities. Rather than an indication of a biogeographical pattern, we are of the opinion that the low similarity with neighbouring countries is primarily an artifact resulting from taxonomic inconsistencies. The checklist presented here could serve as a valuable tool to reveal the seaweed diversity in Vietnam and to stimulate intraregional comparative research.

Macroalgal composition and its association with local hydrodynamics in the Laje de Santos Marine State Park, southwestern Atlantic, São Paulo, Brazil

The Laje de Santos Marine State Park (LSMSP), located in southeastern Brazil, is the only marine park in São Paulo State. This conservation unit has been established as a protected area of high biological diversity. Despite its importance for the conservation of the marine biota, little is known about the park's seaweed flora. The objectives of this study were as follows: to furnish increased knowledge of the composition of the macroalgae in the Park area; to relate the area's macroalgal composition to the presence of an important water mass in the region, the South Atlantic Central Water (SACW); and to investigate the possible influence of the Port of Santos on the composition of the macroalgae of the LSMSP. This study registered 31 new records for the LSMSP, 11 for São Paulo State, four for Brazil, one for the western Atlantic and one for the South Atlantic Ocean, in addition to the possible occurrence of one new species of Osmundea (Rhodomelaceae) and one new genus belonging to Ceramiaceae. The taxonomic composition of the macroalgae had a direct correlation with the arrival of the SACW in the summer-fall season. The SACW generated a strong thermocline and increased the supply of nutrients in the water column. Hydrodynamic and dispersion modeling analyses suggested that the Port of Santos influenced the composition of the LSMSP phycoflora.

The invasive seaweed Sargassum filicinum (Fucales, Phaeophyceae) is on the move along the Mexican Pacific coastline

Abstract Sargassum filicinum Harvey is an important ecological engineer in the subtidal regions of northeastern Asian waters, as it forms marine forests that provide shelter for invertebrates and fishes. First discovered in Long Beach Harbor, CA, USA, in 2003, S. filicinum was thought to occur mainly in the California Channel Islands and near Ensenada, Mexico. However, during a survey from 2007 to 2009, we found S. filicinum off Isla Natividad, which is an extension of its range 550 km south of its last recorded location in the Mexican Pacific. Morphological and molecular data support the identification of the species. Considering its faster spread from Ensenada to Isla Natividad (4 years) than Sargassum muticum (14 years), S. filicinum may follow the path of S. muticum and arrive at the subtropical-tropical Pacific coast of Mexico. Although S. muticum has become well established within the local seaweed flora, S. filicinum may replace native Sargassum species and change the composition of local marine floras.

The dispersal of Halimeda in northern hemisphere mid-latitudes: Palaeobiogeographical insights

The bryopsidalean alga Halimeda gained an important role as carbonate producer in Cenozoic tropical coral reefs and became a significant constituent of the modern Mediterranean seaweed flora. There are, however, open questions at which time the thermophile alga appeared in the cooler Mediterranean Sea and why it is not detected in coral reefs of the modern Persian Gulf. To unravel the biogeography and ecology of Halimeda at its northern margin of distribution, we use fossil Halimeda records of the Central Paratethys/Medditerranean for comparison of the geological, (palaeo)ecological and evolutionary dispersal constraints of the alga in the Miocene and Holocene Persian Gulf. The revealed spatial and temporal distribution patterns of Halimeda in the regions of the Mediterranean and Arabian seas identify water temperature as the major ecological constraint and the extreme Plio-Pleistocene climate changes as the motor for the dispersal and evolution of Halimeda in higher latitudes. Generally, the distribution of tropical species in higher latitudes was related to warm climate intervals during the Neogene. Accordingly, the available (palaeo)biogeographic data implies that the warm-adapted ancestors of the present-day Mediterranean H. tuna population possibly entered the Mediterranean Sea during the mid-Pliocene global warmth and became isolated during subsequent cooling. It also implies that the warm Persian Gulf water is probably unsuitable for the cool-adapted H. discoidea population in the Gulf of Oman and that its tropical ancestors could have reached the Gulf of Oman only during a Pleistocene glacial phase when monsoon-induced upwelling of cold water in the Arabian Sea was reduced and the Persian Gulf fell dry. This example demonstrates the limitation of the actualistic palaeontological approach when using biota at the edges of their distribution range as palaeoclimate proxy.

The seaweeds of Angola: the transition between tropical and temperate marine floras on the west coast of southern Africa

The seaweed flora of Angola is relatively poorly known. Most of the 124 records listed for the country come from a 1974 British Natural History Museum expedition to the central and southern parts of that country. Previous biogeographic studies treated the Angolan seaweed flora as a whole and grouped it with those of certain West African islands as transitional between a Tropical West African seaweed flora (essentially extending from Senegal to Gabon) and temperate floras to the north and south of this truly tropical region. In the present study a total of 99 species and subspecies of seaweeds was collected from the intertidal zone and shallow sublittoral zones at five sites in the north of Angola and four sites in the south. The biogeographic distributions of our records were examined and compared with the temperate flora of Namibia to the south and the flora of Ghana to the north (as an example of a well-studied Tropical West African flora). Multivariate analyses of our presence/absence records showed differences between northern and southern sites (cluster analysis [Jaccard, average linkage] and detrended correspondence analysis). All Angolan sites were clearly different from floras of south, central and northern Namibia, which are considered to be strictly temperate in nature. Northern Angolan sites grouped more closely with Ghana than with southern Angolan sites. Distribution patterns within Angola are discussed in relation to monthly sea surface temperature data that were processed for this region. We conclude that the overall affinities of the Angolan seaweed flora, as represented by our collections, are Tropical West African, but with a well-developed temperate element in southern Angola (from about 13° S) comprising mainly cooler-water species from the Benguela Marine Province of Namibia and western South Africa. Our collections add about 45 species to the Angolan seaweed flora, raising the total number of species to around 169. This total approaches that of Ghana which, with about 200 species, is considered to have the richest seaweed flora in Tropical West Africa.

The Hawaiian Rhodophyta Biodiversity Survey (2006-2010): a summary of principal findings

BackgroundThe Hawaiian red algal flora is diverse, isolated, and well studied from a morphological and anatomical perspective, making it an excellent candidate for assessment using a combination of traditional taxonomic and molecular approaches. Acquiring and making these biodiversity data freely available in a timely manner ensures that other researchers can incorporate these baseline findings into phylogeographic studies of Hawaiian red algae or red algae found in other locations.ResultsA total of 1,946 accessions are represented in the collections from 305 different geographical locations in the Hawaiian archipelago. These accessions represent 24 orders, 49 families, 152 genera and 252 species/subspecific taxa of red algae. One order of red algae (the Rhodachlyales) was recognized in Hawaii for the first time and 196 new island distributional records were determined from the survey collections. One family and four genera are reported for the first time from Hawaii, and multiple species descriptions are in progress for newly discovered taxa. A total of 2,418 sequences were generated for Hawaiian red algae in the course of this study - 915 for the nuclear LSU marker, 864 for the plastidial UPA marker, and 639 for the mitochondrial COI marker. These baseline molecular data are presented as neighbor-joining trees to illustrate degrees of divergence within and among taxa. The LSU marker was typically most conserved, followed by UPA and COI. Phylogenetic analysis of a set of concatenated LSU, UPA and COI sequences recovered a tree that broadly resembled the current understanding of florideophyte red algal relationships, but bootstrap support was largely absent above the ordinal level. Phylogeographic trends are reported here for some common taxa within the Hawaiian Islands and include examples of those with, as well as without, intraspecific variation.ConclusionsThe UPA and COI markers were determined to be the most useful of the three and are recommended for inclusion in future algal biodiversity surveys. Molecular data for the survey provide the most extensive assessment of Hawaiian red algal diversity and, in combination with the morphological/anatomical and distributional data collected as part of the project, provide a solid baseline data set for future studies of the flora. The data are freely available via the Hawaiian Algal Database (HADB), which was designed and constructed to accommodate the results of the project. We present the first DNA sequence reference collection for a tropical Pacific seaweed flora, whose value extends beyond Hawaii since many Hawaiian taxa are shared with other tropical areas.

The biogeography of seaweeds in Southeast Alaska

AbstractAim This article reviews the history of seaweed collections in Southeast Alaska from the early Russian explorers to contemporary efforts. It summarizes other studies of Southeast Alaskan seaweeds from a biogeographical perspective, and compares the known seaweed flora near three population centres (Ketchikan, Sitka and Juneau) with those of other regions within Alaska, and with nearby regions.Location For this article, Southeast Alaska includes all inside and outside waters of the Alexander Archipelago from Dixon Entrance (54°40′ N, 133°00′ W) to Icy Point (58°23′10″ N, 137°04′20″ W).Methods The literature on seaweeds occurring in Southeast Alaska is reviewed from a biogeographical perspective, and herbarium records for Southeast Alaska from the Alaska Seaweed Database project are used to provide an overview of the biogeography of the area. Records for the population centres of Ketchikan, Sitka and Juneau are compared with records from other areas within Alaska and with nearby regions to determine floristic similarities.Results Southeast Alaska has the most diverse seaweed flora of any region of Alaska. A list of species known to occur in Southeast Alaska is appended (in Supplementary Material) and includes their reported occurrences in three population centres (Juneau, Ketchikan and Sitka). Recognition of at least three distinct biogeographical areas associated with these three centres is supported by a comparison of their floras with those of other regions in the North Pacific. A close relationship of some species with conspecifics in the north‐west Atlantic is also noted. In contrast, ecological, physiological and genetic differentiation of Southeast Alaskan seaweeds from conspecifics in Washington State or even from different areas of Southeast Alaska are documented. A ShoreZone coastal habitat system, which is being implemented to inventory and map the entire shoreline of Southeast Alaska, is defining new biogeographical units called ‘bioareas’ on the basis of the distribution of canopy kelps and lower intertidal algal assemblages.Main conclusions Southeast Alaska has the most diverse seaweed flora of any region of Alaska. This is a reflection of its extensive coastline, with varied past and present environmental conditions. Different parts of Southeast Alaska show similarities to different areas outside Southeast Alaska. Despite this, much remains to be learned about the biogeography of seaweeds in Southeast Alaska, and many questions remain to be answered.

The seaweeds of Kenya: Checklist, history of seaweed study, coastal environment, and analysis of seaweed diversity and biogeography

The seaweeds of Kenya are relatively well documented in comparison with the marine floras of other countries in the Indian Ocean. A checklist is provided of the seaweeds recorded, which includes a total of 386 species (214 red algae, 116 green algae and 56 brown algae), plus an additional 19 infra-specific taxa. This is the first detailed list for almost 30 years, with a 29% increase in species compared to the previous listing. The history of seaweed study in Kenya and the Kenyan coastal environment as a habitat for seaweeds are discussed in detail. An ordination analysis of the global biogeographic relationships of the Kenyan seaweed flora shows clearly the internal consistency of the Indo-Pacific seaweed flora at this large scale. Data on Indian Ocean relationships show that the Kenyan flora produces a distinct grouping of seaweed floras from Tanzania, Madagascar, Mozambique and the Indian Ocean coast of South Africa, which is somewhat separated from the floras of the rest of the Indian Ocean. The data reveal that Mozambiquan seaweeds are seriously understudied, with only 26% of the Kenyan flora having been recorded in that country, compared with 68% in Tanzania, 41% in Madagascar, and 43% in South Africa.