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First report of the intentionally introduced kelp, Saccharina japonica, in the Pacific coast of southern Chile
Abstract
We report for the first time the occurrence of the Japanese kelp Saccharina japonica on the Pacific coast of southern Chile following an illegal introduction for aquaculture purposes. In November 2020, a citizen complaint indicated that the non-native kelp was being illegally farmed in Canal Caicaén. Specimens of the non-native kelp were collected during successive surveys for molecular and morphological analyses, and reproductive viability tests. The species was determined using two mitochondrial molecular markers, COI and trnW-L. Phylogenetic analysis confirmed the taxonomic identity of the specimen as S. japonica and revealed a genetic similarity with S. japonica × S. latissima hybrid cultivars Sanhai and Rongfu. In April 2021, several adult specimens became fertile at the farm site and the laboratory and released meiospores were able to develop into embryos after 15–20 days of incubation. These findings underline the risk for this kelp to disperse and colonize in the natural surrounding habitat, with potential impacts on local coastal ecosystems.
... The potential gene flow from cultivated kelp to wild counterparts may alter the genetic constitution of the latter in regions where both coexist (Camus et al. 2022;Robinson et al. 2023;Shan et al. 2019). This scenario exists in the Atlantic salmon farming industry, in which genetic traces from escapee fish have been detected in the genetic make-up of wild populations (Bentsen and Thodesen 2005;Bolstad et al. 2017). ...
Wild-type sporophytes of Saccharina japonica have been recurrently observed on the infrastructures of kelp farming rafts in China's northern production region (Liaon-ing and Shandong provinces). However, there are few detailed reports delineating their origin, genetic attributes and affiliations with farmed populations. Using microsatellite molecular analyses, we furnish a comparative analysis of the populations sampled from these rafts at one of the historical kelp farming regions Rongcheng city (Shandong province), both before and after the "2021-2022 kelp farming disaster", in conjunction with two field populations from nearby intertidal zones where natural populations prevail. The results show that the wild kelp populations on the kelp farming rafts in 2023 had originated from the wild populations dwelling in intertidal zones several kilometers away, rather than from the artificially cultivated kelp cultivars.
... However, neither Atlantic salmon nor Pacific oyster are native to British Columbia, and both species have had deleterious effects on native species 46,47 . Farmed outside their native ranges, algae species can also become invasive, as evidenced by the introduction and rapid spread of Japanese kelp in China 48 . The ecological and socio-ecological consequences of Japanese kelp outside its native range remain unclear, but the potential impacts of invasive algal species are well-documented 49 . ...
Aquaculture has the potential to support a sustainable and equitable food system in line with the United Nations Sustainable Development Goals (SDG) on food security, climate change, and biodiversity (FCB). Biological diversity amongst aquaculture organisms can drive diverse contributions to such goals. Existing studies have assessed the performance of a limited number of taxa in the general context of improving aquaculture production, but few explicitly consider the biological attributes of farmed aquatic taxa at the FCB nexus. Through a systematic literature review, we identify key traits associated with FCB and evaluate the potential of aquaculture to contribute to FCB goals using a fuzzy logic model. The majority of identified traits are associated with food security, and two-thirds of traits linked with food security are also associated with climate change or biodiversity, revealing potential co-benefits of optimizing a single trait. Correlations between FCB indices further suggest that challenges and opportunities in aquaculture are intertwined across FCB goals, but low mean FCB scores suggest that the focus of aquaculture research and development on food production is insufficient to address food security, much less climate or biodiversity issues. As expected, production-maximizing traits (absolute fecundity, the von Bertalanffy growth function coefficient K, macronutrient density, maximum size, and trophic level as a proxy for feed efficiency) highly influence a species’ FCB potential, but so do species preferences for environmental conditions (tolerance to phosphates, nitrates, and pH levels, as well as latitudinal and geographic ranges). Many highly farmed species that are typically associated with food security, especially finfish, score poorly for food, climate, and biodiversity potential. Algae and mollusc species tend to perform well across FCB indices, revealing the importance of non-fish species in achieving FCB goals and potential synergies in integrated multi-trophic aquaculture systems. Overall, this study provides decision-makers with a biologically informed assessment of desirable aquaculture traits and species while illuminating possible strategies to increase support for FCB goals. Our findings can be used as a foundation for studying the socio-economic opportunities and barriers for aquaculture transitions to develop equitable pathways toward FCB-positive aquaculture across nuanced regional contexts.
... The potential gene flow from cultivated kelp to wild counterparts may alter the genetic constitution of the latter in regions where both coexist (Camus et al. 2022;Robinson et al. 2023;Shan et al. 2019). This scenario exists in the Atlantic salmon farming industry, in which genetic traces from escapee fish have been detected in the genetic make-up of wild populations (Bentsen and Thodesen 2005;Bolstad et al. 2017). ...
Wild-type sporophytes of Saccharina japonica have been recurrently observed on the infrastructures of kelp farming rafts in China’s northern production region (Liaoning and Shandong provinces). However, there are few detailed reports delineating their origin, genetic attributes and affiliations with farmed populations. Using microsatellite molecular analyses, we furnish a comparative analysis of the populations sampled from these rafts at one of the historical kelp farming regions Rongcheng city (Shandong province), both before and after the “2021–2022 kelp farming disaster”, in conjunction with two field populations from nearby intertidal zones where natural populations prevail. The results show that the wild kelp populations on the kelp farming rafts in 2023 had originated from the wild populations dwelling in intertidal zones several kilometers away, rather than from the artificially cultivated kelp cultivars.
... Furthermore, there is no legislation in place to oversee management and monitoring of hybridization products, either planned or accidental. Recently, an illegal cultivation of the Asian kelp Saccharina japonica was reported in southern Chile [17], revealing not only problems for timely introduction detections in Chilean borders but also a slow regulatory framework to diminish introduction consequences, lasting months to take actions after spotting the cultivation scheme. Moreover, the introduction area poses restricted access as the case is still under criminal investigation, hence Chile has the potential to produce seaweeds at a commercial level of at least one species (G. ...
Seaweed farming worldwide has increased considerably in the last century. Latin America (LATAM) has an
enormous potential to contribute within the medium/long term to global seaweed production. However, the
seaweed sector is not exempted by risks (e.g. diseases and pests) overall understudied in the region, reason why
biosecurity and traceability measurements may be needed to some extent. In this study, policies concerning
biosecurity in seaweed aquaculture in Argentina, Brazil, Chile, Colombia, Mexico and Peru were analyzed and
classified for different categories. The results suggest that most of LATAM policies tend to focus on prevention
measures, especially in ecological biosecurity problems, which are included mostly in general aquaculture leg�islations. Contrarily, economic and environmental risks are to a lesser extent covered. Furthermore, cryptic
ecological aspects associated with farming such as introduction of host for diseases or genetic pollution are often
overlooked, and therefore poorly managed. Within LATAM countries, Chile has the highest specificity in
seaweed-exclusive legislation, likely associated to recent problems with pests and introduction of exotic species.
Overall, there is a lack of information related to biosecurity risks of seaweed aquaculture in LATAM, similar to
what had happened to other globally relevant producers in the southeastern Pacific that have experienced serious
biosecurity problems in the recent years. Seaweed aquaculture is relatively incipient in LATAM region, but its
sustainability as well as the associated food security systems may be at risk, unless new policies make compatible
seaweed production and biosecurity practices.
Globally, China has the largest scale of kelp cultivation and production operations. However, its kelp aquaculture industry is suffering from declining germplasm diversity, degradation of agronomic traits, the presence of polluted environments, changing ocean conditions and increasing anthropological interference. This review covers two of the most commercially important kelp species in China, viz. Saccharina japonica and Undaria pinnatifida. It summarizes the history of their cultivation, production, economic and ecological benefits, their breeding programmes (e.g. inter‐ and intra‐specific hybridization and marker‐assisted selection) and efforts towards population genetic diversity and conservation. The article focuses on three significant challenges, for example genetic cross‐contamination between the wild and farmed kelp populations, ocean warming and ocean acidification. Accordingly, we outline the steps required to provide several intervention measures, for example (i) collection and preservation of wild and cultivated kelp germplasm; (ii) selection of suitable cultivation sites under changing environmental conditions; (iii) developing stress‐resistant cultivars; and finally, (iv) adoption of innovative cultivation models. The review concludes with genome‐based, designs for molecular breeding and calls for the establishment of an East Asian Kelp Consortium (EAKC). Collectively, the Chinese kelp industry could provide beneficial goods and services, for example bioenergy to fine chemicals and environmental benefits, such as carbon capture, pH amelioration and provision of habitat for many other marine species of commercial value. The strategies proposed in this article thus have the potential to not only improve but also reinvigorate the kelp industry in China and nearby Japan and Korea, in the context of both environmental health and economic benefits.
Macrocystis pyrifera and Lessonia spicata are economically and ecologically relevant brown seaweeds that recently have been classified as members of two separated families within Laminariales (kelps). Here we describe for the first time the Macrocystis pyrifera x Lessonia spicata hybridization in the wild (Chiloe Island, Southeastern Pacific), where populations of the two parents exist sympatrically. Externally, this hybrid exhibited typical features of its parents M. pyrifera (cylindrical and flexible distal stipes, serrate frond margins and presence of sporophylls) and L. spicata (rigid and flat main stipe and first bifurcation), as well as intermediate features between them (thick unfused haptera in the holdfast). Histological sections revealed the prevalence of mucilage ducts within stipes and fronds (absent in Lessonia) and fully developed unilocular sporangia in the sporophylls. Molecular analyses confirmed the presence of the two parental genotypes for ITS1 nrDNA and the M. pyrifera genotype for two predominantly maternally inherited cytoplasmic markers (COI and rbcLS spacer) in the tissue of the hybrid. A metabolome-wide approach revealed that this hybrid is more chemically reminiscent to M. pyrifera. Nevertheless, several hits were identified as Lessonia exclusive or more remarkably, not present in any of the parent. Meiospores developed into apparently fertile gametophytes, which gave rise to F1 sporophytes that reached several millimeters before suddenly dying. In-vitro reciprocal crossing of Mar Brava gametophytes from both species revealed that although it is rare, interfamilial hybridization between the two species is possible but mostly overcome by pseudogamy of female gametophytes.
We present the latest version of the Molecular Evolutionary Genetics Analysis (MEGA) software, which contains many sophisticated
methods and tools for phylogenomics and phylomedicine. In this major upgrade, MEGA has been optimized for use on 64-bit computing
systems for analyzing bigger datasets. Researchers can now explore and analyze tens of thousands of sequences in MEGA. The
new version also provides an advanced wizard for building timetrees and includes a new functionality to automatically predict
gene duplication events in gene family trees. The 64-bit MEGA is made available in two interfaces: graphical and command line.
The graphical user interface (GUI) is a native Microsoft Windows application that can also be used on Mac OSX. The command
line MEGA is available as native applications for Windows, Linux, and Mac OSX. They are intended for use in high-throughput
and scripted analysis. Both versions are available from www.megasoftware.net free of charge.
The commercially important brown alga Saccharina japonica in China has been believed to be accidentally introduced from Japan in 1920s. Meanwhile, spontaneous populations in the wild are assumed to be derived from the locally farmed populations. Spontaneous populations are often observed in the subtidal zones and on the cultivation infrastructure near farmed populations in the north of China. However, the genetic connectivity between these sympatric spontaneous and farmed populations remains unclear. Here, three commonly farmed cultivars (farmed populations) and three spontaneous populations (two from subtidal zones and one from cultivation rafts) were sampled from a typical kelp farm in Dalian, China, and analyzed with ten polymorphic microsatellite markers. Genetic diversity of farmed populations was found to be higher than that of the subtidal spontaneous populations. Neighbor joining cluster analysis based on genetic distance, Bayesian model-based structure analysis, and discriminant analysis of principal components revealed significant genetic divergence between the farmed populations and the subtidal spontaneous ones. Gene flow out of farmed populations to the subtidal spontaneous populations was revealed to be very limited, but gene flow in the contrary direction was more prominent. The spontaneous sporophytes on the structural rafts contained pedigree from both farmed and subtidal spontaneous populations. Results of this study may help us to understand reciprocal impacts between sympatric spontaneous and farmed populations of S. japonica.
In this paper we propose a checklist of 14 species of exotic seaweeds on the Chilean coast, and three species which, being native to the Chilean coast, have been introduced in areas outside their natural range. This list was compiled from previously published checklist, debugged the misidentified records, and incorporating new ones. The distribution of exotic seaweeds is not homogeneous along the coast, but it is concentrated in areas near ports and aquaculture centers. Most species display a fairly bounded distribution, and only four tend to invade (i.e., increase its range of distribution over time). However, considering that most introductions are recent (the last 60 years) and the positive relationship between amplitude of the distribution range and residence time of species on the Chilean coast, we suggest that some of these species may be in an expansion phase, which would explain its restricted distribution. This work not only updates the information related to exotic seaweed on the Chilean coast, but also allows us to understand the invasion process, through the analysis of the patterns described in these systems.
Glacial vicariance is regarded as one of the most prevalent drivers of phylogeographic structure and speciation among high-latitude organisms, but direct links between ice advances and range fragmentation have been more difficult to establish in marine than in terrestrial systems. Here we investigate the evolution of largely disjunct (and potentially reproductively isolated) phylogeographic lineages within the amphi-boreal kelp Saccharina latissima s. l. Using molecular data (COI, microsatellites) we confirm that S. latissima comprises also the NE Pacific S. cichorioides complex and is composed of divergent lineages with limited range overlap and genetic admixture. Only a few genetic hybrids were detected throughout a Canadian Arctic/NW Greenland contact zone. The degree of genetic differentiation and sympatric isolation of phylogroups suggest that S. latissima s. l. represents a complex of incipient species. Phylogroup distributions compared with paleo-environmental reconstructions of the cryosphere further suggest that diversification within S. latissima results from chronic glacial isolation in disjunct persistence areas intercalated with ephemeral interglacial poleward expansions and admixture at high-latitude (Arctic) contact zones. This study thus supports a role for glaciations not just in redistributing pre-existing marine lineages but also as a speciation pump across multi-glacial cycles for marine organisms otherwise exhibiting cosmopolite amphi-boreal distributions.
Marine invasion ecology and management have progressed significantly over the last 30 years although many knowledge gaps and challenges remain. The kelp Undaria pinnatifida, or “Wakame,” has a global non-native range and is considered one of the world's “worst” invasive species. Since its first recorded introduction in 1971, numerous studies have been conducted on its ecology, invasive characteristics, and impacts, yet a general consensus on the best approach to its management has not yet been reached. Here, we synthesize current understanding of this highly invasive species and adopt Undaria as a case study to highlight challenges in wider marine invasion ecology and management. Invasive species such as Undaria are likely to continue to spread and become conspicuous, prominent components of coastal marine communities. While in many cases, marine invasive species have detectable deleterious impacts on recipient communities, in many others their influence is often limited and location specific. Although not yet conclusive, Undaria may cause some ecological impact, but it does not appear to drive ecosystem change in most invaded regions. Targeted management actions have also had minimal success. Further research is needed before well-considered, evidence-based management decisions can be made. However, if Undaria was to become officially unmanaged in parts of its non-native range, the presence of a highly productive, habitat former with commercial value and a broad ecological niche, could have significant economic and even environmental benefit. How science and policy reacts to the continued invasion of Undaria may influence how similar marine invasive species are handled in the future.
La costa chilena presenta menos reportes de especies introducidas respecto a otras costas a nivel mundial, lo que podría corresponder a un fenómeno natural generado por condiciones oceanográficas, o bien a un artefacto producido por falta de información disponible. Mediante el análisis de 71 trabajos indexados en Web of Science, relacionados con ecología de invasiones marinas en la costa chilena, publicados entre 1998-2014, determinamos el estado actual de esta disciplina en Chile, e identificamos las tendencias de las investigaciones realizadas. La mayoría de las publicaciones se relacionan con especies en etapa de naturalización, y pocas con especies invasoras. El número de publicaciones por año incrementa linealmente, sugiriendo un creciente interés de la comunidad científica respecto al tema. La cantidad de información disponible (i.e., número de publicaciones) no es homogénea entre las regiones administrativas, y la mayoría de los trabajos son realizados sectores puntuales dentro de cada región (usualmente cercanos a la capital regional). Regiones con alto tráfico marítimo (e.g., Valparaíso, Magallanes) han sido muy poco estudiadas. A excepción de la región de Coquimbo y Los Lagos, los trabajos por región apuntan a unos pocos taxa. Muy pocos trabajos abarcan grandes escalas espaciales, aunque varios de ellos realizan experimentos a escalas de tiempo mayores (e.g., mensual, anual). Nuestros resultados permiten sugerir que el número de especies reportadas como introducidas en Chile podría estar subestimado. Observaciones en terreno, actualización periódica de catastros y utilización de herramientas moleculares, son propuestos como medidas para una mayor comprensión del tema a nivel nacional.
In this paper, we address several issues related to seaweed domestication from an evolutionary and ecological perspective. We briefly cover the history of human interactions with seaweed and assess the importance of pre-domestication evolutionary processes. The various steps of the trajectory from wild to domesticated seaweeds are discussed for five crop seaweeds (i.e. Saccharina japonica (kombu), Pyropia sp. (nori), Undaria pinnatifida (wakame), Gracilaria chilensis (pellilo) and Kappaphycus sp.) to evaluate their domestication status. We show that seaweed domestication resulted from long-term interactions between humans, seaweeds, and environmental factors. This interplay has deeply modified the coastal ecosystem – sometimes with very detrimental effects (pests and invasions) – but was a key element in the evolutionary process leading to domestication. We then highlight the challenges for future research on seaweed domestication and show how better integration of knowledge on ecology and genetic diversity of wild populations and on the selective pressures exerted by cultivators can promote sustainable seaweed aquaculture.
Saccharina japonica is a commercially and ecologically important seaweed and is an excellent system for understanding the effects of domestication on marine crops. In this study, we used 19 selected simple sequence repeat (SSR) markers to investigate the influence of domestication on the genetic diversity and structure of S. japonica populations. Wild kelp populations exhibited higher genetic diversity than cultivated populations based on total NA, HE, HO, NP and AR. Discriminant analysis of principal components (DAPC), a neighbour-joining (NJ) tree and STRUCTURE analyses indicated that S. japonica populations could be divided into two groups (a cultivated/introduced group and a wild indigenous group) with significant genetic differentiation (P < 0.0001). Divergent selection, continuous inbreeding and inter-specific hybridization have caused the divergence of these two genetically separate gene pools. The significant genetic differentiation between northern and southern cultivated populations appears to be due to inter-specific hybridization and wild germplasm introduction during the domestication process. In addition, the cultivation of S. japonica has not resulted in any serious genetic disturbance of wild introduced S. japonica populations. An understanding of the genetic diversity and genetic structure of domesticated S. japonica will be necessary for further genetic improvement and effective use of germplasm.
ABSTRACTDictyota cyanoloma has recently been described from the Mediterranean Sea and Macaronesia but doubt had arisen as to whether this species was truly native in Europe. The species is mainly found on non-natural substrata (harbour walls, marinas, boat hulls, etc.), strongly suggesting that it is an introduction. Molecular sequence information from historical herbarium samples proves the presence of D. cyanoloma in the Adriatic Sea as early as 1935. Since approximately the year 2000, however, the number of records as well as the geographic range of the species has expanded significantly. The present-day distribution of D. cyanoloma occupies most of the Mediterranean Sea, Macaronesia, NW Africa and southern Portugal, but recent records from Galicia and SW England (Falmouth, Cornwall) indicate that the species is rapidly expanding northward. Collections from Australia demonstrated that the species is also present from Perth in Western Australia, over much of the southern Australian coastline up to Mi
Although the original Saccharina japonica populations in China are assumed to have been accidentally introduced from Japan in 1920s, few investigations have been performed to prove it. Genetic structure analysis is expected to shed light on this question. In the present study, 11 highly polymorphic microsatellite markers were employed to analyze the genetic structure of representative populations of S. japonica in the Northwest Pacific, including the four varieties from Japan. Populations from China had a much lower level of genetic diversity than the ones from Japan in terms of the number of alleles, private alleles and locally common alleles, and the values of heterozygosity, suggestive of the founder effect in the introduced populations. Both the Bayesian model-based and genetic distance-based analyses revealed three major clusters: (1) S. japonica var. japonica, var. religiosa, and var. ochotensis from Hokkaido, as well as the populations from Korea and Russia; (2) populations from China; and (3) var. diabolica. Saccharina japonica var. diabolica harbored the highest number of private alleles, with three of them having a frequency of 1.00 at three loci, which have the potential to be used as specific markers to distinguish this variety from others. Significant genetic differentiation was found between almost all the populations except for a few cultivated populations from China. Populations from China were most closely related to S. japonica var. japonica, which was in turn most close to var. religiosa and the Korean population. The microsatellite markers used in this study were shown to be polymorphic enough to decipher the subtle genetic structure of S. japonica, including the different varieties.
We conducted a bibliographic survey, adding 69 taxa to a published list of 277 seaweeds, thereby updating the total worldwide list of non-native and cryptogenic seaweeds to 346. Polysiphonia Greville and Hypnea J.V. Lamouroux species were the most common taxa on this list, and the Mediterranean Sea and the NE Atlantic bioregions have received most of the 346 taxa. The most important vectors that carry non-native seaweeds are hull fouling and the transport of aquaculture products including ‘blind passengers’. Once a seaweed has arrived in a new location, it can establish a permanent population and spread through natural dispersal or human activity. Non-native seaweeds have negative impacts on native species through competition, habitat destruction and keystone competition, but also positive impacts through habitat formation, food provision and cascading habitat formation. Quantitative meta-analyses have shown that invasive seaweeds typically have a negative effect on local plants, but neutral or positive effects on animal communities. New meta-analyses presented here indicate that impacts increase with the abundance of non-native seaweeds and that non-native seaweeds may increase sample similarity in invaded plant communities, but not in animal communities. The literature on the impact of non-native seaweeds is extensive, but most studies have focused on a few high-profile species. Comprehensive analyses should be done for more species to allow for better predictions. We conclude that non-native seaweeds have altered shallow coastal communities in most biogeographical regions, and impacts will likely increase along with increases in human populations, transport and associated stressors.
Dongfang no.7 (Saccharina japonica) was bred and maintained by hybridizing gametophytes, self-crossing the best individuals, selecting the best self-crossing line and seedling-raising from yearly reconstructed sporophytes. It increased the air dry yield by 43.2% in average over 2 widely farmed controls. Dongfang no.7 was seedling-raised from bulked sporophytes reconstructed from its representative gametophyte clones. Such strategy ensured it against variety contamination due to possible cross fertilization and occasional mixing and inbred depletion due to self-crossing number-limited sporophytes year after year. It derived from an intraspecific hybrid through 4 rounds of self-crossing and selection and retained a certain degree of genetic heterozygosity, thus being immune to inbred depletion due to purification of unknown detrimental alleles. Most importantly, it can be farmed in currently available system as the seedlings for large scale culture can be raised from reconstructed Dongfang no.7 sporophytes. Breeding and maintaining Dongfang no.7 provided a model that other varieties of kelp (S. japonica) and brown algae may follow during their domestication.
The current paper analyses the market, environmental and regulation issues limiting the development of alga aquaculture in Chile and we discuss the possible benefits and uncertainties for the future development of this activity. In particular, Chile has extremely favorable environmental conditions for aquaculture, which allowed that during the past decades the development of a salmon and mussel aquaculture industry and as well as activities with invertebrate species such as abalones and scallops and the red alga Gracilaria chilensis. The benefits and environmental uncertainties for such development are discussed. Chile has extremely favorable environmental conditions for the development of aquaculture, thus we discussed how this business cannot be developed affecting negatively the environmental patrimony of the country. We state that diversification in aquaculture must be based on species with different ecological functions (i.e. primary producers, herbivores, carnivores, and decomposers), which is currently known as Integrated Multi-Trophic Aquaculture (IMTA). This can allow for the balance in energy and matter in coastal systems used in aquaculture. Chile has the opportunity to address these issues in depth, which can allow the country not only to export food products, but also to be a leader in technology for a sustainable aquaculture production worldwide.
Background
Population structure and genetic diversity of marine organisms in the Northwestern Pacific Ocean exhibited complex patterns. Saccharina japonica is a commercially and ecologically important kelp species widely distributed along the coast of Japan Sea. However, it is still poorly known about population genetics and phylogeographic patterns of wild S. japonica populations on a large geographic scale, which is an important contribution to breeding and conservation of this marine crop.
Results
We collected 612 mitochondrial COI and trnW-trnL sequences. Diversity indices suggested that S. japonica populations along the coast of Hokkaido exhibited the highest genetic diversity. Bayesian Analysis of Population Structure (BAPS) revealed four clusters in the kelp species (cluster 1: Hokkaido and South Korea; cluster 2: northwestern Hokkaido; cluster 3: Far Eastern Russia; cluster 4: China). The network inferred from concatenated data exhibited two shallow genealogies corresponding to two BAPS groups (cluster 2 and cluster 3). We did not detect gene flow between the two shallow genealogies, but populations within genealogy have asymmetric gene exchange. Bayesian skyline plots and neutrality tests suggested that S. japonica experienced postglacial expansion around 10.45 ka.
Conclusions
The coast of Hokkaido might be the origin and diversification center of S. japonica. Gene exchange among S. japonica populations could be caused by anthropogenic interference and oceanographic regimes. Postglacial expansions and gene exchange apparently led to more shared haplotypes and less differentiation that in turn led to the present shallow phylogeographical patterns in S. japonica.
Electronic supplementary material
The online version of this article (doi:10.1186/s12862-015-0517-8) contains supplementary material, which is available to authorized users.
Different lamina of Macrocystis pyrifera sporophytes, i.e., sporophylls, pneumatocyst-bearing blades, and apical scimitars, in a wave-sheltered site were found to be fertile. We quantified their sorus surface area, reproductive output (number of spores released) and the viability of released spores (germination rate). Sorus area was greatest on the sporophylls, with sporangia developing on > 57% of the total area and smallest on the pneumatocyst-bearing blades with 21% of the total area bearing sporangia. The apical scimitar released the greatest number of meiospores (cells · mL-1 · cm-2) and the sporophylls the least. Meiospores produced from all types of fertile laminae were equally viable. This reproductive plasticity may enhance reproductive output, and contribute to short and long-distance spore dispersal and the cryptic gametophyte propagule bank for the next generation of sporophytes. This article is protected by copyright. All rights reserved.
In order to produce Laminaria japonica in Jeju as feed for abalone, a transplant experiment was performed with the Baekryungdo and the Wando cultivar stocks at the Udo aquafarm from January to July 2003. Eight water conditions at the aquafarm and eleven traits of the two cultivar stocks were measured once a month. The water temperature ranged from 12.9 to 23.5. The salinity was 31.3-36.8‰ the DO was 5.40-9.86 mg the pH was 7.82-9.61. Concentrations of were 0.02-0.15 M, 2.27-3.49 M, 0.16-0.56 M and 0.07-0.99 M, respectively. The whole frond length of the Baekryungdo and the Wando specimens were 173.84 and 153.67 cm. The blade width, stipe length, blade length, fascia length, blade thickness, total weight and substantiality of the Baekryungdo and the Wando specimens were 14.61 and 13.05 cm, 3.94 and 3.02 cm, 169.88 and 150.65 cm, 155.81 and 137.10 cm, 1.01 and 0.96 cm, 258.04 and 200.96 cm, and 101.56 and 94.62, respectively at the conclusion of the experiment in July. The measurements of the Baekryungdo specimens were slightly higher than those of Wando specimens. The fascia width, stipe thickness and fascia thickness of the Wando specimens were slightly higher than those of the Baekryungdo specimens. The relative growth rates of these traits of two cultivar stocks during the growth test were very similar. Generally, the performance of the Baekryungdo cultivar stock seems to be better than that of the Wando samples. Further study of the physiological ecology for cultivation and breeding is needed in the future.
The two main drivers for intentional introductions of commercial macroalgae are (1) increasing global demand for macroalgae and macroalgal products, and (2) increasing need for alternative and sustainable livelihoods among coastal communities in less-developed countries (particularly to reduce degradation of coral reefs) and in the less-developed rural areas of more-developed countries. The macroalgal species that form the basis for commercial aquaculture (mainly Saccharina japonica (J.E. Areschoug) C.E. Lane, C. Mayes, Druehl et G.W. Saunders, Porphyra species, Undaria pinnatifida, Kappaphycus alvarezii, and Gracilaria species) are thus the ones most likely to be intentionally introduced to other places. The highest-profile cases of "invasive" macroalgae have mainly resulted from unintentional introductions, particularly via shipping. Two cases are species important commercially for aquaculture, U. pinnatifida and K. alvarezii, although the global spread of U. pinnatifida beyond Asia has been caused mainly by shipping. K. alvarezii has been intentionally introduced to many countries for aquaculture and has been reported as invasive in one locality in Hawaii; however, more recently it has emerged that Eucheuma denticulatum is in fact the main culprit at this locality. While environmental problems from intentional introductions have been few compared with those from unintentional introductions, it does not appear that commercial species are, as a group, inherently any more or less risk-prone than most unintentionally introduced species. Only a minority of alien species may ever become invasive, but it is difficult to predict which will become pests. In principle, international norms allow states to intentionally introduce exotic species for commercial purposes, provided that environmental threats can be avoided. In practice, the burden of proof and duty of care about environmental threats and protection of biodiversity is nowadays much higher than before. States cannot take it for granted that alien species may be introduced; new proposals should follow formal risk assessment and monitoring processes that are science-based, and should be strongly justifiable in terms of ability to provide expected economic benefits.
Kelp forests are phyletically diverse, structurally complex and highly productive components of cold-water rocky marine coastlines. This paper reviews the conditions in which kelp forests develop globally and where, why and at what rate they become deforested. The ecology and long archaeological history of kelp forests are examined through case studies from southern California, the Aleutian Islands and the western North Atlantic, well-studied locations that represent the widest possible range in kelp forest biodi-versity. Global distribution of kelp forests is physiologically constrained by light at high latitudes and by nutrients, warm temperatures and other macrophytes at low latitudes. Within mid-latitude belts (roughly 40–60° latitude in both hemispheres) well-developed kelp forests are most threatened by herbivory, usually from sea urchins. Overfishing and extirpation of highly valued vertebrate apex predators often triggered herbivore population increases, leading to widespread kelp deforestation. Such deforestations have the most profound and lasting impacts on species-depauperate systems, such as those in Alaska and the western North Atlantic. Globally urchin-induced deforestation has been increasing over the past 2–3 decades. Continued fishing down of coastal food webs has resulted in shifting harvesting targets from apex predators to their invertebrate prey, including kelp-grazing herbivores. The recent global expansion of sea urchin harvesting has led to the wide-spread extirpation of this herbivore, and kelp forests have returned in some locations but, for the first time, these forests are devoid of vertebrate apex predators. In the western North Atlantic, large predatory crabs have recently filled this void and they have become the new apex predator in this system. Similar shifts from fish-to crab-dominance may have occurred in coastal zones of the United Kingdom and Japan, where large predatory finfish were extirpated long ago. Three North American case studies of kelp forests were examined to determine their long history with humans and project the status of future kelp forests to the year 2025. Fishing impacts on kelp forest systems have been both profound and much longer in duration than previously thought. Archaeological data suggest that coastal peoples exploited kelp forest organisms for thousands of years, occasionally resulting in localized losses of apex predators, outbreaks of sea urchin popu-lations and probably small-scale deforestation. Over the past two centuries, commercial exploitation for export led to the extirpation of sea urchin predators, such as the sea otter in the North Pacific and predatory fishes like the cod in the North Atlantic. The large-scale removal of predators for export markets increased sea urchin abundances and promoted the decline of kelp forests over vast areas. Despite southern California having one of the longest known associations with coastal kelp forests, widespread deforestation is rare. It is possible that functional redundancies among predators and herbivores make this most diverse system most stable. Such biodiverse kelp forests may also resist invasion from non-native species. In the species-depauperate western North Atlantic, introduced algal competitors carpet the benthos and threaten future kelp dominance. There, other non-native herbivores and predators have become established and dominant components of this system. Climate changes have had measurable impacts on kelp forest ecosystems and efforts to control the emission of greenhouse gasses should be a global priority. However, overfishing appears to be the greatest manageable threat to kelp forest ecosystems over the 2025 time horizon. Management should focus on minimizing fishing impacts and restoring popu-lations of functionally important species in these systems.
Background
Saccharina japonica (Areschoug) Lane, Mayes, Druehl et Saunders is an economically important and highly morphologically variable brown alga inhabiting the northwest Pacific marine waters. On the basis of nuclear (ITS), plastid (rbcLS) and mitochondrial (COI) DNA sequence data, we have analyzed the genetic composition of typical Saccharina japonica (TYP) and its two common morphological varieties, known as the “longipes” (LON) and “shallow-water” (SHA) forms seeking to clarify their taxonomical status and to evaluate the possibility of cryptic species within S. japonica.
Results
The data show that the TYP and LON forms are very similar genetically in spite of drastic differences in morphology, life history traits, and ecological preferences. Both, however, are genetically quite different from the SHA form. The two Saccharina lineages are distinguished by 109 fixed single nucleotide differences as well as by seven fixed length polymorphisms (based on a 4,286 bp concatenated dataset that includes three gene regions). The GenBank database reveals a close affinity of the TYP and LON forms to S. japonica and the SHA form to S. cichorioides. The three gene markers used in the present work have different sensitivity for the algal species identification. COI gene was the most discriminant gene marker. However, we have detected instances of interspecific COI recombination reflecting putative historical hybridization events between distantly related algal lineages. The recombinant sequences show highly contrasted level of divergence in the 5’- and 3’- regions of the gene, leading to significantly different tree topologies depending on the gene segment (5’- or 3’-) used for tree reconstruction. Consequently, the 5’-COI “barcoding” region (~ 650 bp) can be misleading for identification purposes, at least in the case of algal species that might have experienced historical hybridization events.
Conclusion
Taking into account the potential roles of phenotypic plasticity in evolution, we conclude that the TYP and LON forms represent examples of algae phenotypic diversification that enables successful adaptation to contrasting shallow- and deep-water marine environments, while the SHA form is very similar to S. cichorioides and should be considered a different species. Practical applications for algal management and conservation are briefly considered.
We reviewed over 407 global seaweed introduction events and have increased the total number of introduced seaweed species to 277. Us-ing binomial tests we show that several algal families contain more successful invaders than would be expected by chance, highlighting groups that should be targeted for management. Hull-fouling and aquaculture are the most significant sources of seaweed invaders and should be carefully regulated. The ecological effects of introduced seaweeds have been studied in only 6% of the species, but these studies show mostly negative effects or changes to the native biota. Herbivores generally prefer native to introduced seaweeds, and are unlikely to control spread, as they can do in other habitats. Undis-turbed marine communities can be at least initially resistant to most introduced seaweeds aside from the siphonous green species; how-ever, disturbances and eutrophication can facilitate invasion. Major research gaps include community-level ecological studies and eco-nomic assessments.
The kelp Undaria pinnatifida(Phaeophyceae) is a seaweed native to northeast Asia, but during the last two decades, it has been accidentally or intentionally introduced in several temperate coasts worldwide. In central Patagonia (Argentina), this species was first detected in late 1992, and it is progressively spreading from the point of introduction. Through a manipulative experiment involving Undaria removal in 2001, we found that its presence is associated with a dramatic decrease in species richness and diversity of native seaweeds in Nuevo Gulf. Future prospects are worrisome, as, in addition to the negative impact from a biodiversity viewpoint, native commercial macroalgae and invertebrates might also be affected.
Introductions of non-indigenous species to new ecosystems are one of the major threats to biodiversity, ecosystem functions and services. Globally, species introductions may lead to biotic homogenisation, in synergy with other anthropogenic disturbances such as climate change and coastal pollution. Successful marine introductions depend on (1) presence of a transport vector, uptake of propagules and journey survival of the species; (2) suitable environmental conditions in the receiving habitat; and (3) biological traits of the invader to facilitate establishment. Knowledge has improved of the distribution, biology and ecology of high profile seaweed invaders, e.g. Caulerpa
taxifolia, Codium fragile ssp. tomentosoides, Sargassum
muticum, and Undaria
pinnatifida. Limited, regional information is available for less conspicuous species. The mechanisms of seaweed introductions are little understood as research on introduced seaweeds has been mostly reactive, following discoveries of introductions. Sources of introductions mostly cannot be determined with certainty apart from those directly associated with aquaculture activities and few studies have addressed the sometimes serious ecological and economic impacts of seaweed introductions. Future research needs to elucidate the invasion process, interactions between invaders, and impacts of introductions to support prevention and management of seaweed introductions.
The 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. ARTICLE HISTORY
Seaweed aquaculture is growing worldwide in coastal areas as an alternative to increasing income and food security. Despite these potentials, there is growing concern about the distribution of net benefits and sustainability of local communities. Consequently, governance must be able to include cross-sectoral dimensions related to aquaculture development given these challenging scenarios. Chile, the main seaweed producer of the western world, is implementing a new policy framework for sustainable development of small-scale seaweed aquaculture, principally through the transfer of funds for artisanal fishermen and small-scale farmers. Although supported by the existing demand for raw material and a reliable technological basis for cultivation, lack of added-value products and low-priced biomass may have a critical impact on the livelihood of those involved in aquaculture operations creating uncertainties for sustainable expansion. This study applied a multi-criteria decision analysis (i.e., hybrid SWOT – AHP analysis) to interpret stakeholders’ multidimensional perceptions on policy implementation gaps regarding the current status of Chilean small-scale seaweed aquaculture. Both social and institutional dimensions presented diverging opinions among counterparts with relation to economic, technological and environmental topics. This operating inconsistency will require significant attention on complementary objectives beyond funding, such as innovation, enhancement of commercial channels, the creation of internal markets, mainstreaming, education and social equity. Comprehensive and efficient governance able to promote participatory management may improve its own capabilities to overcome an increasingly unfavourable scenario for small-scale seaweed aquaculture.
Marine invasive macroalgae can have severe local-scale impacts on ecological communities. The kelp Undaria pinnatifida is one of the most successful marine invasive species worldwide, and is widely regarded as one of the worst. Here, we review research on Undaria in Australasia, where the kelp is established throughout much of New Zealand and south-eastern Australia. The presence of Undaria for at least three decades in these locations makes Australasia one of the longest-invaded bioregions globally, and a valuable case study for considering Undaria's invasion success and associated impacts. In Australasia, Undaria has primarily invaded open spaces, turf communities, and gaps in native canopies within a relatively narrow elevation band on rocky shores. Despite its high biomass, Undaria has relatively few direct impacts on native species, and can increase community-wide attributes such as primary productivity and the provision of biogenic habitat. Therefore, Australasian Undaria research provides an example of a decoupling between the success and impact of an invasive species. Undaria will most likely continue to spread along thousands of kilometres of rocky coastline in temperate Australasia, due to its tolerance to large variations in temperature, ability to exploit disturbances to local communities, and the continued transfer among regions via vessel movements and aquaculture activities. However, the spread of Undaria remains difficult to manage as eradication is challenging and seldom successful. Therefore, understanding potential invasion pathways, maintaining native canopy-forming species that limit Undaria success, and effectively managing anthropogenic vectors of Undaria spread, should be key management priorities.
Optimal conditions for sorus formation of Laminaria japonica were investigated by culturing discs of the sporophyte in bottles. All discs formed sori in the seven combinational conditions of temperature (5-15°C), irradiance (33.2-116 μE•m⁻²•s⁻¹) and photoperiods (16:8, 12:12 and 8:16h LD) in nutrientrich medium. Sorus formation occurred earlier at 15°C than at 5 and 10°C and were largest in the area at 15°C. Sori grew larger under high irradiance (116 μE•m⁻²•s⁻¹) than under low irradiances (66.4 and 33.2 μE•m⁻²•s⁻¹), but the initiation of sorus formation was not influenced by irradiance. Sorus formation was earlier in 8:16h LD than in 12:12 and 16:8h LD. Rapid formation of large sori occurred at high temperatures even in a long photoperiod. Sorus formation in discs in nutrient-poor medium was slower than that in discs in nutrient-rich medium, in which all discs formed large sori. Most discs in nutrient-poor medium formed very small sori. These results indicate that water temperature and nutrient conditions strongly affect both to the induction and expansion of sorus formation.
In old China there were very few people engaged in the study of the algae,but in new China, freshwater and marine algae are studied by over onehundred old and new phycologists. There is now an algal biotechnologyindustry consisting of an aquaculture industry, producing large amounts ofthe seaweeds Laminaria, Porphyra, Undaria, Gracilaria,eucheumoids, and the microalgae Dunaliella and Spirulina. There is also a phycocolloid industry, producing algin, agar andcarrageenan; an industry producing chemicals and drugs, such as iodine,mannitol, phycocyanin, β-carotene, PSS (propylene glycol alginatesulfate) and FPS (fucose-containing sulfated polysaccharides) and anindustry producing food, feed and fertilizer. The Laminariacultivation industry produces about 900,000 t dry Laminaria,probably the largest producer in the world and 13,000 t algin,undoubtedly one of the largest algin producer in the world.
The systematics of Laminaria japonica J. E. Areschoug, L. religiosa Miyabe, L. ochotensis Miyabe and L. diabolica Miyabe, which are similar morphologically and restricted to the coastline of northern Japan, was re-examined. From the morphological observations, it was concluded that the discrimination of the four species based on their morphological features was problematic. The results of crossbreeding experiments and molecular phylogenetic analyses suggest that these species are not genetically isolated. Consequently, we concluded that these four species should be revised as four varieties of one species: L. japonica J. E. Areschoug var. japonica, var. religiosa, var. ochotensis and var. diabolica.
Optimal conditions for sorus formation of Laminaria japonica were investigated by culturing discs of the sporophyte in bottles. All discs formed sori in the seven combinational conditions of temperature (5-15°C), irradiance (33.2-116 μE·m-2·s-1) and photoperiods (16:8, 12:12 and 8:16 h LD) in nutrient-rich medium. Sorus formation occurred earlier at 15°C than at 5 and 10°C and were largest in the area at 15°C. Sori grew larger under high irradiance (116μE·m-2·s-1) than under low irradiances (66.4 and 33.2 μE·m-2·s-1), but the initiation of sorus formation was not influenced by irradiance. Sorus formation was earlier in 8:16 h LD than in 12:12 and 16:8 h LD. Rapid formation of large sori occurred at high temperatures even in a long photoperiod. Sorus formation in discs in nutrient-poor medium was slower than that in discs in nutrient-rich medium, in which all discs formed large sori. Most discs in nutrient-poor medium formed very small sori. These results indicate that water temperature and nutrient conditions strongly affect both to the induction and expansion of sorus formation.
Macroalgae are a significant component of historic and modern invasions, with association to a wide variety of transport mechanisms. These transport mechanisms pose specific constraints on the ways by which species can be taken up, transported and released into a new environment. Currently operating transport mechanisms for marine macroalgae are either associations with intentional introductions (translocations for aquaculture, aquarium or live seafood trade) or accidental introductions (mainly as hull-fouling). A number of potential management options exist, including the development of international instruments and regional agreements. The development of treatment options for hull fouling, the most significant and poorly managed transport mechanism for macroalgae, is of urgent need. Our current ability to identify which species are likely to invade next is limited. However, an examination of the synergies between species' functional traits, transport constraints, and recipient community attributes will likely provide possible options in the future.
Seaweed population biology has received far less attention than trophic dynamics, yet is critically important in establishing and maintaining algal communities. Complex life histories of habitat-forming kelps and fucoids, including spores, gametophytes, gametes, and microscopic and macroscopic benthic stages, must be considered within the context of their highly dynamic nearshore environments. We evaluate differences within and between kelps and fucoids in life histories as they affect population biology; dispersal and potential limitations in population establishment; macroscopic stages and variations in survival and longevity affecting stand structure; and microscopic stage responses to disturbance and variation in the physical environment. We suggest that the commonly made comparisons of seaweeds with terrestrial seed plants are misleading because of large differences in morphology, environments, and the ephemeral nature of propagule banks in the sea. We conclude that progress in understanding ...
An experimental evaluation of habitat modification on species richness and abundance by enhancing spatial heterogeneity using artificial reefs was carried out in Seno Reloncaví, southern Chile (41°29′S, 72°54′W). Because of the potential applications of artificial reefs for fisheries, particular attention was paid to commercially valuable species. In October 1990, hollow (30 cm)3 concrete blocks with 20 cm diameter openings on their six sides were arranged in two layers to form 0.6 m high reefs of 0.81 m2 basal area. Five of these reefs were deployed at depths of 13 to 18 m on sandy and rubble bottoms. Colonization and community development was quantitatively recorded using SCUBA. Three major faunal groups—fish, crustaceans, and sea urchins—increased their abundance on the reefs. Commercially valuable species included adults of two crabs: Cancer edwardsi and Homalaspis plana. The reefs also served as recruiting sites for juvenile rockfish (Sebastes capensis) and as feeding and courtship arenas for tripterygids (Tripterygion cunninghami). A few other crab and fish species also appeared in and around the reefs but without becoming residents. Algal colonization was slow and their abundance was notably controlled by sea urchins (Arbacia dufresnei). Artificial habitats placed on low-relief bottoms of the Channel Region of Southern Chile can potentially enhance the abundance of some commercially valuable species. The effect of artificial reefs on species richness (especially fish) was not striking, however. This is most likely related to a natural paucity of species in the region.
Responses of the sporophytes of Laminaria japonica to blue, red and white lights were investigated using segments, discs and whole plants. The relative growth rate with regard to the blade's length and width showed no difference among the light conditions during 2 weeks of culturing. On the contrary, the elongation rates of the stipe and the holdfast were 1.7–2.5 times higher under red light than that under white light as a control. Callus formation in the segments was also promoted more under red light conditions than under white or blue light. Blue light irradiation resulted in a 48% and 12% decrease in the relative growth rate of the stipe and the holdfast, respectively, in comparison with the control. When sporophyte discs were cultured for 10 weeks, all discs formed zoosporangial sori 2–3 weeks earlier under blue light than under white light. However, red light inhibited the formation of zoosporangia. Indoleacetic acid (IAA) oxidase activity was about two-fold higher under blue light than under red light, suggesting that the difference in response between the blue and red light conditions is related to the internal IAA level of the tissues. The developmental, reproductive and morphological effects of blue and red lights will be useful for the artificial control of the life cycle of Laminaria plants and for the development of more efficient cultivation techniques.
Kelp intergeneric laminarialean hybridizations and hybridization protocol were assessed using seven northeast Pacific kelp species: Alaria marginata Postels and Ruprecht, Costaria costata (C. A. Agardh) Saunders, Eisenia arborea Areschoug, Laminaria saccharina (L) Lamouroux, Lessoniopsis littoralis (Tilden) Reinke, Macrocystis integrifolia Bory, and Nereocystis leutkeana (Mertens) Postels and Ruprecht. Survival and development of sporophyte morphologies derived from selfings, separate males and females, and reciprocal crosses were evaluated over 30 weeks of cultivation. All cultures were initiated from cloned gametophytes. Two closely related species, Laminaria angustata Kjellman and L. japonica Areschoug, demonstrated the efficacy of long-term (up to 30 years) cloned gametophytes in hybridization studies. Sporophyte morphologies appeared in 34%–69% of control and hybridization trials, and 6%–16% of all trials produced sporophytes in control and hybridization conditions that persisted through 30 weeks of cultivation. Sporophytes in control and hybridization conditions could appear normal or abnormal. Usually, the morphology of sporophytes in hybridizations and female controls resembled the female parent, whereas the sporophytes in male controls often had an abbreviated morphology, lacking definitive generic features. Species-specific rDNA internal transcribed spacer molecular primers were used to determine the parentage of five putative hybrids. Only the L. japonica♀/L. angustata♂ hybrid bore both parental genomes. That negative controls could produce persistent and normal-appearing sporophytes negates their value and emphasizes the importance of molecular confirmation in hybridization studies. These findings were applied to critique the only known wild intergeneric hybrid, Pelagophycus/Macrocystis.
In old China there were very few people engaged in the study of the algae,but in new China, freshwater and marine algae are studied by over onehundred old and new phycologists. There is now an algal biotechnologyindustry consisting of an aquaculture industry, producing large amounts ofthe seaweeds Laminaria, Porphyra, Undaria, Gracilaria,eucheumoids, and the microalgae Dunaliella and Spirulina. There is also a phycocolloid industry, producing algin, agar andcarrageenan; an industry producing chemicals and drugs, such as iodine,mannitol, phycocyanin, -carotene, PSS (propylene glycol alginatesulfate) and FPS (fucose-containing sulfated polysaccharides) and anindustry producing food, feed and fertilizer. The Laminariacultivation industry produces about 900,000 t dry Laminaria,probably the largest producer in the world and 13,000 t algin,undoubtedly one of the largest algin producer in the world.
Changes in assemblages of plants, macroinvertebrates and fishes on three eastern Tasmanian reefs were monitored over 12 months in replicated control blocks and adjacent 10×12-m blocks cleared of fucoid, laminarian and dictyotalean algae. Removal of canopy-forming plants produced less change to biotic assemblages than reported in studies elsewhere, with the magnitude of change for fish and invertebrate taxa lower than variation between sites and comparable to variation between months.The introduced annual kelp Undaria pinnatifida exhibited the only pronounced response to canopy removal amongst algal taxa, with a fivefold increase in cleared blocks compared to control blocks. Marine reserves are suggested to assist reef communities resist invasion by U. pinnatifida, through an indirect mechanism involving increased predation pressure on sea urchins and reduced formation of urchin barrens that are amenable to U. pinnatifida propagation.Large invertebrates were more associated with turfing algae or the reef substratum than the macroalgal canopy. The herbivorous sea urchin Heliocidaris erythrogramma and abalone Haliotis ruber showed the strongest response to clearing amongst common macroinvertebrate species, with a halving of population numbers. Observed densities of the common monacanthid fish Acanthaluteres vittiger also declined by about 50%. The relatively high level of resistance shown by eastern Tasmanian reef biota to patch disturbance was attributed largely to high diversity and biomass of turfing macroalgae damping effects of canopy clearance.
Persistence of annual plant populations requires sufficient seeds and suitable habitat for development and growth each year. Competition with perennials may prevent within site persistence and result in “fugitive” annual populations. Comparisons have been made between the population biology of annual macroalgae and terrestrial plants, but demographic information necessary to make strong comparisons is lacking for most of these algae, and life history differences may make such comparisons questionable. We studied population dynamics of the kelp Alaria marginata to determine if it was an annual and, if so, how populations persisted. This kelp is the dominant macroalga on exposed mid to low rocky intertidal shores along the Big Sur coast of California. Experimental clearings at two sites were used to assess recruitment timing and survivorship. Sporophytes were collected monthly to determine growth and fecundity. Recruitment occurred in late winter to early spring, primarily on geniculate corallines and residual A. marginata holdfasts. Thinning was inversely related to density, and occurred during the February through July growing season as larger thalli rapidly increased in length (up to 1.4 m month− 1) and formed a thick canopy. Sorus development was positively related to size, began as early as March, peaked in late August–October, and decreased as adults were removed by winter surf. Spore release was generally highest (108–109 spores individual− 11 h− 1) between October and January and associated with high water motion. Survivorship of sporophytes beyond one year was < 1%, showing the populations were annual.
Like any other living organisms, algae are plagued by diseases caused by fungi, protists, bacteria or viruses. As aquaculture continues to rise worldwide, pathogens of nori or biofuel sources are becoming a significant economic burden. Parasites are also increasingly being considered of equal importance with predators for ecosystem functioning. Altered disease patterns in disturbed environments are blamed for sudden extinctions, regime shifts, and spreading of alien species. Here we review the biodiversity and impact of pathogens and parasites of aquatic primary producers in freshwater and marine systems. We also cover recent advances on algal defence reactions, and discuss how emerging technologies can be used to reassess the profound, multi-faceted, and so far broadly-overlooked influence of algal diseases on ecosystem properties.
The authors have listed 85 species of macrophytes that have probably been introduced to the Mediterranean. Among them, nine species can be considered as invasive, i.e., playing a conspicuous role in the recipient ecosystems, taking the place of keystone species and/or being economically harmful: Acrothamnion preissii, Asparagopsis armata, Lophocladia lallemandii, Womersleyella setacea (Rhodophyta), Sargassum muticum, Stypopodium schimperi (Fucophyceae), Caulerpa racemosa, Caulerpa taxifolia and Halophila stipulacea (Plantae). These data fit well the Williamson and Fitter's "tens rule", which states that, on average, 1 out of 10 introduced species becomes invasive. Though some features (e.g. life traits, geographical origin) can increase the likelihood of a successful invasion, the success of invaders is far from being predictable. Since the beginning of the 20th century, the number of introduced species to the Mediterranean has nearly doubled every 20 years. Should these kinetics continue, and according to the tens rule, it can be expected that 5-10 newly introduced macrophytes shall become invasive in the next 20 years.
There are increasing concerns regarding the delivery, movement and presence of non-indigenous or invasive species into marine and estuarine areas. Such introductions can be on a large scale such as the movement to higher latitudes of species as the result of global warming. Alternatively, such species can be introduced into a marine or estuarine area as the result of small-scale events, such as the liberation from waste-water discharges, aquaculture or ballast-water discharge. However, if such introductions lead to a successful colonisation then they can become a wide-scale problem. This paper considers the introduction of such non-indigenous and invasive species as biological pollution and biological pollutants and it discusses the definitions and concepts used in assessing and managing marine pollution in relation to these terms.
The introduction of alien species (AS) in marine environments is a factor of disturbance that can be viewed as a pollution agent. Using basic information on abundance and distribution of alien species, we developed an index that classifies AS impacts on native species, communities, habitats and ecosystem functioning. This method can be used to evaluate impact at five different levels of biopollution, fitting within the existing schemes for water quality assessment. Both spatial and temporal comparisons are possible. The assessments may also be used to evaluate management performance where avoidance measures were necessary and assist in preventing further unwanted introductions. Such assessments made for the same areas over time provide opportunities for measuring change in biopollution. We have tested the method using four different well-studied areas within the Baltic Sea (brackish to freshwater environments) for two different times, 20 years apart. Further developments of the scheme may be needed to cover some specific cases and taxonomic groups according to their life history.
World-wide electronic publication
- M D Guiry
- G M Guiry Algaebase
M.D. Guiry G.M. Guiry AlgaeBase. World-wide electronic publication, National
University of Ireland, Galway. https://www.algaebase.org; searched on 01 October
2021.