Showing papers by "Alejandro H. Buschmann published in 2016"

Global patterns of kelp forest change over the past half-century

Abstract: Kelp forests (Order Laminariales) form key biogenic habitats in coastal regions of temperate and Arctic seas worldwide, providing ecosystem services valued in the range of billions of dollars annually. Although local evidence suggests that kelp forests are increasingly threatened by a variety of stressors, no comprehensive global analysis of change in kelp abundances currently exists. Here, we build and analyze a global database of kelp time series spanning the past half-century to assess regional and global trends in kelp abundances. We detected a high degree of geographic variation in trends, with regional variability in the direction and magnitude of change far exceeding a small global average decline (instantaneous rate of change = −0.018 y−1). Our analysis identified declines in 38% of ecoregions for which there are data (−0.015 to −0.18 y−1), increases in 27% of ecoregions (0.015 to 0.11 y−1), and no detectable change in 35% of ecoregions. These spatially variable trajectories reflected regional differences in the drivers of change, uncertainty in some regions owing to poor spatial and temporal data coverage, and the dynamic nature of kelp populations. We conclude that although global drivers could be affecting kelp forests at multiple scales, local stressors and regional variation in the effects of these drivers dominate kelp dynamics, in contrast to many other marine and terrestrial foundation species.

Aquaculture as yet another environmental gateway to the development and globalisation of antimicrobial resistance.

Abstract: Aquaculture uses hundreds of tonnes of antimicrobials annually to prevent and treat bacterial infection. The passage of these antimicrobials into the aquatic environment selects for resistant bacteria and resistance genes and stimulates bacterial mutation, recombination, and horizontal gene transfer. The potential bridging of aquatic and human pathogen resistomes leads to emergence of new antimicrobial-resistant bacteria and global dissemination of them and their antimicrobial resistance genes into animal and human populations. Efforts to prevent antimicrobial overuse in aquaculture must include education of all stakeholders about its detrimental effects on the health of fish, human beings, and the aquatic ecosystem (the notion of One Health), and encouragement of environmentally friendly measures of disease prevention, including vaccines, probiotics, and bacteriophages. Adoption of these measures is a crucial supplement to efforts dealing with antimicrobial resistance by developing new therapeutic agents, if headway is to be made against the increasing problem of antimicrobial resistance in human and veterinary medicine.

Identification and efficient extraction method of phlorotannins from the brown seaweed Macrocystis pyrifera using an orthogonal experimental design

Abstract: The brown seaweed contains a type polyphenol compound characteristic of its species, the phlorotannins, which are produced from the polymerization of phloroglucinol units. They have been extensively studied due to their pharmacological and nutraceutical properties, but there is still a need for an optimized extraction protocol. In this study, the brown seaweed Macrocystis pyrifera was employed to determine the best conditions for extraction of phlorotannins. A set of different variables were evaluated such as the use of pre-treatment, type of solvent, drying temperature, particle size, temperature and extraction time as well as the solid/liquid ratio upon extraction. The optimal conditions for the extraction of phlorotannins were: pre-treatment with hexane, extraction with water, drying temperature 40 °C, particle size below 1.4 mm, at 55 °C for 4 h and a solid-to-liquid ratio of 1:15. Under these conditions, the concentration of phlorotannins achieved in the extract was 200.5 ± 5.6 mg gallic acid equivalent (GAE)/100 g dry seaweed (DS) and total antioxidant activity of the extract of 38.4 ± 2.9 mg trolox equivalent (TE)/100 g DS. Further, it was possible to identify two phlorotannins through HPLC-ESI-MS analyses: phloroeckol and a tetrameric phloroglucinol. These phlorotannins have been reported in the literature to have an antidiabetic effect and prevention of Alzheimer's disease for phloroeckol, and free radical scavenging ability and antiallergic effect for tetrameric phloroglucinol. Therefore, the extract of phlorotannins has potential as medicinal foods or therapeutics for human health applications.

Scaling up bioethanol production from the farmed brown macroalga Macrocystis pyrifera in Chile

Abstract: Interest in third-generation biomass such as macroalgae has increased due to their high biomass yield, absence of lignin in their tissues, lower competition for land and fresh water, no fertilization requirements, and efficient CO2 capture in coastal ecosystems. However, several challenges still exist in the development of cost-effective technologies for processing large amounts of macroalgae. Recently, genetically modified micro-organisms able to convert brown macroalgae carbohydrates into bioethanol were developed, but still no attempt to scale up production has been proposed. Based on a giant kelp (Macrocystis pyrifera) farming and bioethanol production program carried out in Chile, we were able to test and adapt this technology as a first attempt to scale up this process using a 75 L fermentation of genetically modified Escherichia coli. Laboratory fermentation tests results showed that although biomass growth and yield are not greatly affected by the alginate:mannitol ratio, ethanol yield showed a clear maximum around a 5:8 alginate:mannitol ratio. In M. pyrifera, a much greater proportion of alginate and lower mannitol abundance is found. In order to make the most of the carbohydrates available for fermentation, we developed a four-stage process model for scaling up, including acid leaching, depolymerization, saccharification, and fermentation steps. Using this process, we obtained 0.213 Kg ethanol Kg−1 dry macroalgae, equivalent to 9.6 m3 of ethanol hectare−1 year−1, reaching 64% of the maximum theoretical ethanol yield. We propose strategies to increase this yield, including synthetic biology pathway engineering approaches and process optimization targets. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd

Germplasm banking of the giant kelp: Our biological insurance in a changing environment

Abstract: Genetic diversity is being lost at a fast pace — seaweeds are no exception. The giant kelp, Macrocystis pyrifera, forms vast underwater forests in both hemispheres and is a key species for ecosystem functioning. But this species is also a commodity product. M. pyrifera is harvested for its chemical compounds (e.g. alginates) and for feedstock (e.g. abalone). In the past 5 years, some companies tried new farming techniques to boost biomass production for biofuel conversion. But the lack of sustainable management can lead to genetic erosion and degradation of livelihoods. Often, the natural genetic populations are not described, and we may be losing what is yet to be found. Aiming to alert and prevent this situation, we developed a germplasm bank based on the genetic diversity of M. pyrifera from Chile. We preserved female and male gametophytes in separate, from 3 genetic populations in low light, at 10 °C, in Provasoli media but without cryoprotective agents. After 5 years in cold storage, we show for the first time gametophyte viability up to 89% and viability differences between genetic populations. We discuss the benefits of this germplasm bank considering sustainability of seaweed production, food security pressures, and climate change.

Production and economic assessment of giant kelp Macrocystis pyrifera cultivation for abalone feed in the south of Chile

Abstract: Kelp biomass availability for mass abalone cultivation remains a critical issue in Chile. The technical and economic feasibility of a commercial scale kelp farming activity has not been established. This study describes the production and economic results of a pilot scale unit installed in southern Chile. Our results show 25 kg m−1 of production over a 9-month spring-summer period, and 16.2 kg m−1 during the autumn-winter period. These values indicate that a total biomass production of 41.3 kg (wet) m−1 year−1 can be obtained by placing the culture lines at 4 m intervals. High quality animal food-grade plants with a 9% protein content, over 5 m in length were harvested. Sensitivity analysis showed that by cultivating 30–50 ha with a market value of US$ 78 ton−1, a return on investment can be made after the first year.

Linking global patterns of kelp forest change and variation in climate over the past half-century

Abstract: One of the great challenges of modern marine ecology is detecting trajectories of change in marine ecosystems and identifying the underlying drivers. Kelps (Laminariales) form key biogenic habitat in coastal regions of temperate and polar seas worldwide, providing ecosystem services valued in the range of billions of dollars annually. While local evidence suggests that these important ecosystems are increasingly threatened by shifts in climate stressors, no comprehensive global analysis of change in kelp abundance currently exists. Here, we build and analyze a worldwide database of kelp time series to assess global and regional changes in kelp abundances over the past half-century and then merge it with data on global long-term changes in climate drivers. We detected a small global decline in kelp, with significant variation that was characterized by both increases and decreases on a regional scale. Merging kelp abundance with environmental data (temperature and wave heights) allowed us to attribute some of the spatial variation in regional trajectories to changes in climate drivers. Specifically, kelp has been declining in regions throughout the globe with warming seawater temperatures; with wave disturbances driving losses at lower latitudes. Our results highlight the importance of examining contrasting regional signals of change. These regional contrasts can provide the variability we need to discover generalized links between synchrony in global phenomenon, such as climate change, and the future of kelp ecosystems around the globe.