Digital library

  • Macroalgae represent a potential biomass source for the production of bioethanol or biogas. Their use, however, is limited by several factors including, but not restricted to, their continuous supply for processing, and low biofuel yields. This review examines recent pretreatment processes that have been used to improve the yields of either biogas or bioethanol from macroalgae. Factors that can influence hydrolysis efficiency and, consequently, biofuel yields, are highly affected by macroalgal composition, including content of salts, heavy metals, and polyphenols, structural make-up, as well as polysaccharide composition and relative content of carbohydrates. Other factors that can influence biofuel yield include the method of storage and preservation.

    Author(s): Supattra Maneein , John J. Milledge, Birthe V. Nielsen, Patricia J. Harvey
  • The vast majority of global aquaculture production (c. 88%1) is either marine plants, filter feeding shellfish, or omnivorous/freshwater finfish with a low requirement for marine protein and lipid derived feeds. However, the remaining small (but important to Scotland and other EU27 states) percentage are carnivorous finfish species, which require commercially formulated feeds that contain high levels of protein and lipid. The traditional source of the raw materials to manufacture these diets has been fishmeal and fish oils derived from the feed fish capture sector – largely to ensure that the amino acid and fatty acid components are nutritionally suitable for the finfish species being cultivated.
     
    This issue was discussed at a recent Marine Conservation Society workshop - “Feeding the Fish of the Future – Alternative choices for aquafeeds”2, which highlighted the increasing need for the aquaculture feeds of the future to rely on alternative, non-marine or nontraditional marine ingredients. The event also highlighted the growing interest and concern for the future formulation of aquaculture feeds by policy makers, environmental NGO’s, feed companies, and retailers, including the extent to which algae, as a “marine” source, could potentially be a viable ingredient for aquafeeds.
     
    Author(s): Scottish Aquaculture Research Forum (SARF)
  • Though microalgae and macroalgae are considered as a potential feedstock for biofuel and industrially important co-products extraction, still there are several research barriers on the commercialization of algae-based fuels and products. Based on these bottlenecks, this review underpins the biochemical composition of micro- and macroalgae regarding biofuel production and bioactive compounds extraction. Further, the second chapter summarizes the various cultivation systems for rapid generation of macroalgal biomass. Micro- and macroalgae are untapped for bioenergy production to assess the feasibility of future green fuel sustainability. In general, algae were considered as a potential source for various applications worldwide owing to their rich and enormous bioactive potential. Therefore, a separate section devoted to recognize the crucial role and biological activities of primary and secondary metabolites in micro- and macroalgal species, their significant contribution as functional foods or therapeutic agents in nutraceutical and pharmaceutical industries. The extensive discussion on the phenolics, flavonoids and pharmacological properties of other bioactive compounds extracted from microalgae has been provided. Further, carbohydrates, proteins (phycobiliproteins and phycoerythrin) and their organic extraction from macroalgal strains (seaweeds) were well described. This review paper describes the importance of bioactive compounds and their value in the various other markets besides biofuel production.

    Author(s): Kulanthaiyesu Arunkumar, Thangavel Mathimani, B. Ramesh Kumar, M.P. Sudhakar
  • Preliminary investigation on the culture of Siganus canaliculatus in floating cages in mandapam coastal water has revealed that the fish has high culture potential in the region. It is euryhaline, inhabiting areas where salinities range from 17 ppt to 37.0 ppt. The Juvenile are abundant in the area of reef and seaweed bed and collecting in traps near mandapam. Natural occurrence of juveniles of S. canaliculatus in large quantity was noticed during February through May in the Gulf of Mannar. The fish feeds mainly on seaweeds. It is reported that the fish can reach a marketable size of 20 cm fork length in 6 months. The rabbit fish is cultured in South East Asian countries. India has enormous potential for rabbit fish culture.

    Author(s): M.Jaikumar
  • As the third generation biofuel feedstock to confront with energy crisis, microalgae have great potential for the exploration of renewable energy fields, whereas the high cost related to biomass production and harvesting is the main bottleneck to hinder the applications on a large scale. To mitigate the environmental impacts in a sustainable mode, co-culturing filamentous fungi with targeted microalgae is a superior method to efficiently accumulate and harvest the total biomass. This paper serves as a base to review current advances in pelletization of microalgae with fungi for the co-cultivation process. The pellet formation is initially introduced, and then electrostatic interactions, hydrophobic interactions and specific components on cell walls as the main harvesting mechanisms are explored and generalized together with the inclusion of critical affecting parameters for efficiency promotion. Apart from the discussion about biomass harvesting, the latest studies of this co-cultivated technology on wastewater treatment in diverse types associated with corresponding removal mechanisms are analyzed as well. Subsequently, this article emphasizes the effects of fungal-algal cultivation on downstream processing for biofuel production, followed by the practical bioenergy conversion performances. Based on the policies support, the implications of this novel co-cultivation technology have shown the potential in further development. Meanwhile, the current challenges and future perspectives about harvesting on a large scale, removal of multiple pollutants and exploration of integrated biorefinery are pointed out systematically. 

    Author(s): Ruoyu Chu, Shuangxi Li, Liandong Zhu, Zhihong Yin, Dan Hu, Chenchen Liu, Fan Mo
  • There is a growing global recognition that microalgae-based biofuel are environment-friendly and economically feasible options because they incur several advantages over traditional fossil fuels. Also, the microalgae can be manipulated for extraction of value-added compounds such as lipids (triacylglycerols), carbohydrates, polyunsaturated fatty acids, proteins, pigments, antioxidants, various antimicrobial compounds, etc. Recently, there is an increasing focus on the co-cultivation practices of microalgae with other microorganisms to enhance biomass and lipid productivity. In a co-cultivation strategy, microalgae grow symbiotically with other heterotrophic microbes such as bacteria, yeast, fungi, and other algae/microalgae. They exchange nutrients and metabolites; this helps to increase the productivity, therefore facilitating the commercialization of microalgal-based fuel. Co-cultivation also facilitates biomass harvesting and waste valorization, thereby help to build an algal biorefinery platform for bioenergy production along with multivariate high value bioproducts and simultaneous waste bioremediation. This article comprehensively reviews various microalgae cultivation practices utilizing coculture approaches with other algae, fungi, bacteria, and yeast. The review mainly focuses on the impact of several binary culture strategies on biomass and lipid yield. The advantages and challenges associated with the procedure along with their respective cultivation modes have also been presented and discussed in detail.

    Author(s): Ayusmita Ray, Manoranjan Nayak, Amit Ghosh
  • Hydrothermal carbonization (HTC) as a promising thermochemical process can convert organic solid wastes (e. g., biomass, plastics) into valuable products (i.e., hydrochar) at relatively low temperatures (180–250 �C) and saturated pressures (2–10 MPa). Hydrothermal conversion generally occurs via dehydration, polymerization and finally carbonization reactions. The carbon materials derived from hydrochar have high potential in various applications such as solid fuel, supercapacitor, fuel cell, and sorbent. Although the energy densification of hydrochar was increased at higher temperatures, most of the benefit was achieved at modest temperatures. Chemical structures of hydrochars include crosslinks of aromatic polymer, surface porosity, organic functional groups and ultimate components. All of these characteristics can be changed significantly by HTC, influencing the reactivity and fuel properties of hydrochars. The reaction pathways including negative and positive effects during (co)-HTC of biomass and plastic wastes are thoroughly concluded. In particular, the co-HTC of chlorinated plastic (e.g., PVC) and biomass can enhance the dechlorination and inorganics removal from hydrochar. 

    Author(s): Yafei Shen
  • According to the Convention on Biological Diversity (CBD), an alien species is a species, sub-species or lower taxon, introduced outside its natural past or present distribution, which includes any part, gametes, seeds, eggs or propagules of such species that might survive and subsequently reproduce (CBD, 2002).

    Invasive Alien Species (IAS) have been identified as one of the significant drivers of global biodiversity, which resulted in species and habitat loss worldwide (Sandilyan, 2016). Ever-increasing globalization and the ongoing environmental changes have facilitated the dissemination of invasive species significantly (Early et al., 2016).

    All major groups including virus, fungi, algae, mosses, ferns, higher plants, invertebrates, fishes, amphibians, reptiles, birds and mammals have been recognized for their invasion potential in different habitats including wetlands. However, plants, insects and mammals comprise the most common types of invasive alien in terrestrial environment (Rejmanek and Richardson, 2000; Sujay et al., 2010), whereas in aquatic habitats, molluscs, fishes, algae, floating and submerged plants are the predominant taxa (Anil et al., 2002; Sandilyan, 2016). In general, invasive species are widely distributed in all kinds of ecosystems. Recent survey highlighted that 17% of the global land area is highly prone to invasion (except Antarctica and glaciated Greenland) (Early et al., 2016). The report also stated that 16% of globally important biodiversity-sensitive areas are highly vulnerable to bioinvasion (Early et al., 2016). I. IntroductionCentre for Biodiversity Policy and Law (CEBPOL)

    Studies have well established that invasive species can influence the species composition, community structure and functions of ecosystems by repressing or excluding native species, either directly by outcompeting them for resources or indirectly by changing the way that nutrients are cycled through the bio-geo system. Most of the time the whole ecosystem may be placed at risk through knock-on effects due to invasion, which results in irretrievable loss to native species that depends on the ecosystem (GISP, 2004; Levine et al., 2003).

    Wetland habitats are highly prone to invasion, especially the coastal habitats which naturally provide several avenues for the invasion (Anil et al., 2002; Sandilyan, 2016). The major pathway for coastal invasion is through ballast water (e.g. Karenia brevis), natural calamity (e.g. Lion fish Pterois volitans) accidental introduction/escape during unscientific coastal aquaculture (e.g. Litopenaeus vannamei) and seaweed culture (e.g. Kappaphycus alvarezii) (Figure 1) (Anil et al., 2002; Brigg et al., 2004). However, a number of studies highlighted about the ballast water issues. Annually, 1 2 billion tonnes of ballast w a t e r is being exchanged throughout the world. A single bulk cargo ship of 200,000 tonnes can carry up to 60,000 tonnes of ballast water (Ibrahim and Manal, 2012; Raghunathan et al., 2013). Every day, nearly 7,000 marine and coastal species travel across the world’s oceans by cargo ships, which silently carry more than 4,500+ different species including microbes, plants and small animals i n t h e i r ballast water tanks. Among them some of the species can evolve as invasive species and cause deleterious impacts to the coastal ecosystem and lead to huge economic loss (WWF, 2009; Ibrahim and Manal, 2012).

    A number of studies have pointed out that marine invasion is highly harmful to ecosystem functions, native species and human health, which may also cause huge economic and biodiversity loss (Anil et al., 2002). For instance, studies highlighted that death of a large number of fishes, sea turtle, sea birds and marine mammals was reported due to harmful algal blooms (HABs) as Impacts of Invasive Alien Species on Indian coastal Ecosystem a result of untreated ballast water discharge (Pierce and Henry, 2008). The HABs, commonly known as ‘Red Tides’, have been identified as a major health hazard. More than 300 algal species which cause red tides have been identified so far, and most of the species produce toxins that are harmful to marine organisms and human. For instance, the microscopic algae Karenia brevis can kill large numbers of fish and other marine organisms including dolphins (Pierce and Henry, 2008). During blooming K. brevis produces/liberates a collection of polyether neurotoxins called brevetoxins. This substance can easily dissolve in the environment and adversely affect the habitat and wildlife of the region. A study in southern Florida disclosed the large-scale mortality of fish, marine turtle, sea birds and mammals due to brevetoxins produced by K. brevis (Pierce and Henry, 2008).

    Researchers clearly state that it is very difficult to control and eradicate the aquatic invasive species that have established themselves in open waters. Only few successful examples are available pertaining to eradication, especially if the invading species was detected at a very early stage inside enclosed areas such as an island or small bay. Using biocides to eradicate the invasive species is the only viable option recommended by experts (Ibrahim and Manal, 2012). On the other hand, prevention and management have been identified as an environmentally friendly way to manage the invasive species.

    Obviously, the need of the hour is for scientific planning to find an early detection and eradication of invasive species in Indian coastal habitats. A group of experts (inter- and intra-science) including taxonomists, ecologists and resource managers should be established for better prevention and effective management of marine invasion. Formulating new strategies and action plans with updated technology will be highly helpful for better management

    Author(s): S. Sandilyan, B. Meenakumari, T.T. Ajith Kumar, Rupam Mandal
  • A PDF on "A seaweed cultivation business - Dream or reality?".

    Author(s): Pål Bakken, Andreas Pütz, Frank Neumann, Luiza Saliba Neves, Hélia Medinas, Artur Simões, Jon Funderud, Svein Jarle Horn, Kaia Kjølbo Rød
  • Scope

    This Bibliography has attempted to cover materials on seaweeds and seaweed products relevant to the tropical Pacific region, particularly the Pacific island countries, although many references also relate to other countries in the Tropics . In addition, references on Ciguatera-causing algae are also included. The bibliography was compiled using a number of sources for the references, including personal libraries. Several databases were machine searched, and most of the Eucheuma references that are included here are post 1987 as the older literature has been adequately reviewed. References on seagrass are also included. There are also several other recent reviews available on related aspects. The Akatsuka volume announced for publication in 1992 should be consulted as should the Proceedings of the XlVth International Seaweed Symposium and a special issue (No.2) of volume 5 of the Journal of Applied Phycology. The "Grey" literature has been more difficult to trace, and undoubtedly pertinent reports have been missed, hence this is not an exhaustive list.

    Author(s): G. R. South, G. Rao, J. L. McLachlan

Pages