Marine algal ecology today faces many of the same problems as ecology in general, e.g. lack of generality of experimental results, the difficulty of making long-term predictions, and an apparent lack of agreement as to what constitutes the proper or 'acceptable' way of doing this particular component of science. These problems, if real, affect marine algal ecology everywhere but, in different geographical areas, specific problems also occur; science in parts of Asia has some problems different from those in other parts of the world. Since its inception, research in marine algal ecology has been motivated by many factors, ranging from traditional needs, to curiosity, to survival, to new technology, and economic needs. Each of these has shaped the questions that have been asked by, and the level ofsupportsociety has been willing to supply to, ecology. For example the requisites oftradition pushed marine ecology to ask questions about food and ceremonial biota, and our fears today about loss of biota are pushing for answers to questions about the means of preserving biodiversity. The limitations of many marine ecological studies have been pointed out by different individuals. Their comments have been valuable in forcing us to examine what we are doing as marine ecologists, and how we are doing it. Ecology, and marine algal ecology with it, has been accused of carrying out small-scale studies that have no greater generality than the sites at which the studies were done, and of using statistical procedures that are wrong or inappropriate; also, there is disagreement within the ecological community of how to correct for these 'faults'. Some of the problems arise due to the nature of our particular science, e.g. working with organisms with differing genetic makeup and sensitivity of experimental results to small changes in initial conditions. Other problems are more likely due to the individuals doing the science, e.g. an inability to be an 'expert' on all areas of knowledge required for a modem ecologist (taxonomy, experimental design, data analysis, etc.), and perhaps an unwillingness to recognize that in some instances different methods of data analysis are applicable and valid. As ecologists, we must come to grip with these problems, both for the sake of our science, and for our own sake as practicing ecologists.
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This article outlines the development of commercial open- water algae farming in Zanzibar in a historic context, with special reference to actual events at the corporate level from the initiation of algae-farming to its present state. These events, which contain policies and intentions of implementation at the producer level, have an array of social implications for the algae-farming communities. The three aspects of these implications are delineated; (i) a changing mode of tenure rights of the farmed lagoon areas; (ii) a changing role for algae farmers, i.e. women; (iii) a qualitative change within the composition of indigenous productive activities, the latter being illustrated by a de- clining activity in agriculture. The article demonstrates the importance of the encounter between an indigenous liveli- hood system and infused incentives pertaining to divergent rationales of livelihood in socioeconomic development processes.
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The developmental regulation of mass cultures of “free-living” conchocelis (suspension cultures) of Porphyra leucosticta from Groton, CT (USA) has been studied in laboratory culture. The conchocelis filaments were vegetatively propagated and maintained in 15 l volumes at 15 °C, 40 μmol m−2 s −1 and 16 L:8 D. Conchosporangia formation was induced after four weeks by increasing the temperature up to 20 °C, maintaining a photon fluence rate of 40 μmol m−2 s −1 and decreasing the photoperiod to 8 L:16 D. Conchosporangial filaments were vegetatively propagated and maintained at these conditions for up to 24 weeks. Suspension cultures of conchosporangial filaments were induced to form and release conchospores (after 6–10 days) by decreasing the temperature to 15 °C, increasing the photon fluence rate to 60–100 μmol m−2 s −1 and lengthening the photoperiod to 12 L:12 D. Conchosporangial formation was found at all photoperiods, however, the ratio of conchosporangia to vegetative conchocelis increased as the photoperiod decreased. With higher photon fluence levels, conchospore release time was decreased, whereas at a temperature of 25 °C spore germination decreased. At their peak release, the quantity of conchospores increased from 7.14 to 18.3 million per gram of conchosporangia with a decrease in conchosporangia density from 1.582 to 1.125 mg ml−1 , respectively. On the average, one gram (dw) of free conchosporangia could release about 20 million conchospores at the peak period. These released conchospores were able to attach, germinate and develop into juvenile blades on the synthetic twine (3–5 mm in diameter) of standard nori nets (1.5 × 18 m). A total of 16 standard nets and eight small nets (2.0 × 2.5 m) were seeded by fixing the culture nets over a rotary wheel in a 2.5 × 2.5 × 0.5 m−3 tank containing the mature conchospore inoculum from the free-living conchosporangia cultures. Four seeded standard nori nets were transferred to the sea for nursery culture in Long Island Sound (USA). Conchosporeling densities from 255 to 325 conchosporelings cm−1 were produced. After 43 days of nursery culture, the blades grew to 1.49 ± 0.14 cm in length. Our results indicate that the use of “free-living” conchocelis suspension cultures may be an effective alternative technology in the commercial production of the Porphyra.
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Tracing large-scale patterns of ecosystem distribution in land and marine environments is a fundamental task of field biology. The resulting patterns often have important implications in ecology, biogeography, and evolution as well as applied consequences in resource management and utilization. Classically, studies of marine ecosystems found at the sea edge, on hard substratum at levels down to 30–40 m, have distinguished three main ecological systems that replace each other at different latitudes. Coral reefs characterize lower latitudes and tropical waters (1), kelp forests replace coral reefs in most cold and temperate waters in both hemispheres (2, 3), whereas thickets of other large brown algae occupy the cold waters around Antarctica (4). Work by Graham et al. (5) included in a recent issue of PNAS changes dramatically this well accepted latitudinal pattern of marine ecosystem distribution. Using a diversity of data, Graham et al. first predicted the widespread occurrence of unexplored, submerged (30- to 200-m depth) kelp habitats in regions between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S). Then, using deep-water SCUBA diving, they documented the presence of extensive kelp forests in eight localities within one of the predicted tropical regions. The emerging picture (Fig. 1A) is one of widespread occurrence of kelp forest formations in both surface and deep waters along most continents.
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Seaweeds, from a biodiversity and ecological point of view, are important as they dominate the rocky intertidal in most oceans, and in temperate and polar regions cover rock surfaces in the shallow subtidal. Seaweeds are used in many maritime countries as a source of food, for industrial applications and as a fertiliser. The major utilisation of these plants as food is in Asia, particularly Japan, Korea and China, where seaweed cultivation has become a major industry. In most western countries, food and animal consumption is restricted and there has not been any major pressure to develop seaweed cultivation techniques. Industrial utilisation is at present largely confined to extraction for phycolloids and, to a much lesser extent, certain fine biochemicals. Fermentation and pyrolysis are not been carried out on an industrial scale at present but are possible options for the 21st century. The present uses of seaweeds are as human foods, cosmetics, fertilisers, and for the extraction of industrial gums and chemicals. They have the potential to be used as a source of long- and short-chain chemicals with functional food, medicinal and industrial uses. Obviously it is of major importance to taxonomically recognize the species one is dealing with as lookalike species may have less desirable compounds or have a complete different chemical make-up. Besides blue-green algae (Cyanobacteria), euglenophytes, charophytes, diatoms, dinoflagellates and cryptophytes there are about 1200 chlorophytes or green algal, 1750 phaeophytes or brown algal and 6000 rhodophytes or red algal species. One way to disseminate information on this natural resource to the public is through AlgaeBase, a database of information on algae that includes terrestrial, marine and freshwater organisms. Currently AlgaeBase contains 123,508 species and infraspecific names, 6,845 images, 42,225 bibliographic items, and 147,275 distributional records. Besides taxonomic information it includes in many cases industrial and other applications, nutritional aspects and other useful information such as distribution. The usefulness of AlgaeBase as a dissemination tool will be presented together with some personal views on dissemination of information on algae for functional food and other purposes.
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The deam of seaweed farmingAs part of a research project that he leads for Connecticut Sea Grant, Charles Yarish and his collaborators have successfully grown and harvested Gracilaria, an economically valuable edible seaweed, in the Sound. Gracilaria is a source of agar, an extract used as a nutrient and stabilzer in foods for humans and shrimp. It’s also known as agar-agar, for growing cultures in labs. It’s also used in salads and as a garnish.
The project is part of an effort involving seaweeds to bring a concept known as Integrated Multitrophic Aquaculture (IMTA) to our midst. That high-faluting name means simply, growing aquatic organisms at different levels in the food chain together, for their mutual benefit. In the process, bioremediation, or natural cleansing of the waters by certain living organisms, also happens. becomes reality in Long Island Sound.
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As global climates warm and habitats are modified, disease is emerging as a major threat to biodiversity. Understanding the causes and consequences of disease and the influence of environmental change on both host organisms and pathogens is critical for the conservation of important ecosystems. Current rates of environmental change are unprecedentedly rapid, due largely to anthropogenic disturbances, further necessitating the study of disease dynamics. In this thesis, I assessed the causes and consequences of a bleaching phenomenon afflicting a chemically-defended macroalga, Delisea pulchra. Broadly, the aims of this study were to characterise patterns of bleaching in D. pulchra and to assess whether they related (directly or indirectly) to environmental factors, either via influences on algal chemical defences and/or bacterial pathogens. Additionally, I aimed to understand the consequences of disease for D. pulchra and its trophic interactions. Bleaching was more common in summer when water temperatures were elevated and was also more prevalent in shallow water habitats than at depth. Bleached algae supported significantly different microbial communities on their surfaces and also had depleted chemical defences (furanones) compared to co-occurring, healthy conspecifics. Bleaching was more likely at high temperatures when algal chemical defences were low or absent, and microorganisms were abundant and this was evident both in natural populations and in experimental manipulations. Inoculation with a candidate pathogen, Ruegeria sp. R11 caused bleaching in novel field inoculation experiments, but infection and bleaching were moderated by algal defences. Exposure to excessive solar radiation indirectly increased algal susceptibility to bleaching by causing a precursor condition (‘fading’), which had depleted furanones. Association with shadeproviding kelps prevented fading and bleaching in D. pulchra individuals. Bleaching had significant, sub-lethal performance consequences for affected algae and also altered trophic interactions between this seaweed and locally abundant macroherbivores. This work provides strong evidence that bleaching in D. pulchra is the result of an environmentally-mediated bacterial infection(s) that occurs when algal defensive chemistry is low. Understanding how environmental change and disease affect habitat-forming organisms like macroalgae is crucial for the study and management of important natural ecosystems under increasing stress.
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The farming of the red seaweed Kappaphycus alvarezii and related species as raw material for the hydrocolloid carrageenan rapidly spread from the Philippines in the late 1960s to Indonesia, Tanzania, and other tropical countries around the world. Although numerous studies have documented positive socioeconomic impacts for seaweed farming, factors such as diseases and distance to export markets have led to an uneven development of the industry. Using standard budgeting techniques, this study adapted production and market data from a FAO-led global review of seaweed farming to develop comparative enterprise budgets for eight farming systems in six countries (Indonesia, the Philippines, Tanzania, India, Solomon Islands, and Mexico). Although the basic technology package is the same across countries, the study revealed large differences in the economic performance of systems due to wide variations in farm prices and the scale of operations. Although seaweed farming is a suitable activity for small-scale producers, a minimum of 2,000 m of cultures lines are still necessary to ensure adequate economic returns. Greater farming plots may be needed if farm prices are well below the average farm prices paid in Indonesia and the Philippines. Policy recommendations are made to improve the economic potential of underperforming systems.
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As the world's population continues to grow, the way in which ocean industries interact with ecosystems will be key to supporting the longevity of food and social securities. Aquaculture is crucial to the future supply of seafood, but challenges associated with negative impacts could impede increased production, especially production that is efcient and safe for the environment. Using the typology established by The Economics of Ecosystems and Biodiversity Initiative, we describe how marine aquaculture could be influential in supporting ecosystem services beyond solely the production of goods, through provisioning services, regulating services, habitat or supporting services, and cultural services. The provision of these services will vary, depending on functional traits of culture species, biotic and abiotic characteristics of the surrounding environment, farm design, and operational standards. Increasing recognition, understanding, and accounting of ecosystem service provision by mariculture through innovative policies, financing, and certification schemes may incentivize active delivery of benefits and may enable efects at a greater scale.
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Alaria esculenta populations from six different geographical locations on the Irish coast were examined for hybridization abilities, growth rates and genetic make-up with a view towards identifying a fast-growing strain suitable for aquaculture. Hybridization experiments under laboratory conditions with the three most geographically dispersed populations showed that all cross combinations were interfertile, although differences were found in survival, and in blade and hapteron morphology. A comparison of relative growth rates showed significant differences amongst the self-crosses and hybrids. The data of the hybridization experiments and growth rates under laboratory conditions show that the best population for the purpose of seaweed aquaculture are the Slea Head and Corbet Head self-crosses and their hybrids. Genetic fingerprinting of the internal transcribed spacer of the ribosomal DNA of five A. esculenta isolates from geographically separated populations in Ireland revealed no restriction length polymorphisms between the tested isolates and show that the A. esculenta populations around the Irish coast are clearly genetically homogenous in respect of the DNA region examined. The genetic analysis, interfertility of the populations, morphology and growth rates are discussed with a view to potential cultivation.
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