Volume 62, Issue 3 - Special issue: Seaweed resources of the world: a 2020 vision. Part 1 / Issue editors: Alan T. Critchley, Anicia Hurtado, Leonel Pereira, Melania Cornish, Danilo Largo and Nicholas Paul

Seaweeds enjoy a rich history as human foodstuff for populations around the world. The omnipresence of seaweeds in all climate belts, the great biodiversity, their bounty of important nutrients, combined with the fact that most seaweeds are edible, suggest that seaweeds have played an important role as human food during human evolution. Seaweeds have served as a cheap and easily accessible crop in the daily fare for coastal populations. In many food cultures, in particular in Southeast Asia, seaweeds have for millennia been considered as valuable sea vegetables. In recent years, regional seaweed cuisines around the world have been rediscovered and reinvigorated, and many chefs up to the top level have initiated, often in collaboration with scientists, a trend towards a new seaweed gastronomy (phycogastronomy).

Neglected tropical diseases (NTDs) are a group of diseases that are predominant in the poorest parts of the world affecting 1.4 billion people. The development of new drugs is urgently needed in order to combat these forgotten diseases. Natural products from marine organisms have been widely explored as a source of new bioactive molecules. However, despite their enormous potential in drug discovery, not even one seaweed-based molecule has entered pre-clinical testing for NTDs. This review gives an overview of the current status of algal natural products against NTDs. The list of compounds is by no means exhaustive, but covers the most important classes of active substances in marine algae against the most studied NTDs.

Alaska has the longest coastline of all of the states in the USA. This coastal zone stretches from the temperate zone to past the Arctic circle. Oceanographic conditions vary from quiet estuaries to exposed open coasts. Water temperatures range from over 20°C in the summer in the south to ice covered water in the north. Consequently, the marine flora is plentiful and diverse with over 500 species of seaweeds. Three species of floating kelps occur from the southern boundary to Kodiak Island and westward along the Aleutian Chain. Species of Fucus are dominant in the intertidal along most of the coastline. There is also an abundance of red algae in the intertidal and subtidal. There is only minimal subsistence and commercial utilization of the seaweed resource. The major commercial use of seaweeds is in the herring spawn-on-kelp fishery. “Black seaweed” ( Pyropia sp.) is a special resource for Alaskan Native subsistence harvest. Recently, there has been increasing interest and activity in the commercial mariculture of kelps such as Saccharina latissima and Alaria marginata .

Chile, located in the southeastern Pacific, possess a high richness of seaweed species, some of which have been traditionally extracted from natural beds for the production of hydrocolloids (e.g. agar, carrageenan and alginates), but still a high proportion of the biomass is being exported as dried material to processors in Asia and Europe. During the period 2006–2016, this tendency has been maintained, but has also started to show signs of changing towards a more sustainable, localized seaweed industry as new actions by the Chilean government provided subsidies to seaweed farming activities and also to investments in local valorization of the resources. This “sea change” has been further supported by an increase in the number of localized scientific and technical studies related to Chilean seaweed resources which has prepared the foundation required in order to move to more advanced stages of local seaweed farming and development of local processing.

This article presents an update of the situation regarding the seaweed resources of Italy 20 years after the first assessment. A search for companies working with seaweed in Italy was conducted. In addition, the literature published over the last 20 years on seaweed biodiversity, alien species, harvests, industrial processing and biomass use was carefully examined and the results are discussed. There are a great many floristic studies, tackling both indigenous and non-indigenous species, although some geographical areas are less studied than others. The number of studies of the use of biomass has increased in the last decade. However, it is apparent that despite the considerable know-how concerning seaweed species, their properties and potential applications, Italy is still behind in seaweed exploitation compared to other countries.

The extensive coastline and numerous islands of Malaysia provide various habitats suitable for the growth of a diversity of the marine macroalgae (seaweeds). Since the last checklist of the Malaysian seaweeds was published in 2006, there has been an increase of 17 families, 32 genera, and 75 species. Seven new species were described. The present tally stands at 459 taxa in 72 families; with 35 species in 12 families of Cyanophyta; 113 species in 16 families of Chlorophyta; 95 species in 8 families of Ochrophyta; and 216 species in 36 families of Rhodophyta. Only three species, Kappaphycus alvarezii , Eucheuma denticulatum and Gracilaria manilaensis , are being cultivated commercially. A small seaweed industry centered in Sabah, produces semi-refined carrageenan, which is mainly exported. Some of the biomass is brought over to Peninsular Malaysia, where seaweed products like desserts, health drinks, soaps and air-fresheners, are manufactured and sold. In 2016, Malaysia produced 205,989 tonnes wet weight seaweeds valued at US$24.83 million. The seaweed industry, can be enhanced by increasing the number of farms and farmers, strengthening local seaweed cooperatives and including them in decision-making, as well as by technological advances in the form of new and improved strains, more efficient seed supply and products.

High diversity of marine macroalgae is reported for Mexican coasts, including numerous endemic species. Seaweed research in Mexico has focused on the northern regions of the Pacific coast (Temperate Pacific and Gulf of California) and on the Mexican Caribbean coast, leaving aside other regions (Tropical Pacific and Gulf of Mexico). Utilization of seaweed resources within the country has been based on artisanal collection of wild populations mainly for polysaccharide extraction, fertilizers, raw material for animal feed and cosmetic products. The main exploitation has occurred along the coasts of Baja California peninsula, based on few species ( Gelidium robustum , Macrocystis pyrifera , Chondracanthus canaliculatus and Gracilariopsis lemaneiformis ). Governmental regulations for management have allowed harvesting to reach approximately 11,500 wet tons per year (2013–2016). Nevertheless, in recent years (2014–2016) the total seaweed import volume has increased (5302 tons per year in average) over the export volume (2156 tons per year in average), suggesting a notably growing demand for seaweed resources in the country and representing an opportunity for investment projects. Several pilot studies on seaweed cultivation in Mexico propose that sustainable aquaculture techniques could complement the harvest in natural populations and ensure a homogeneous production with high quality in the long term.