mekong-river

Jan. 27 – A growing concern for dams the Congo, Mekong, and Amazon Rivers.

The article presented this week in journal club covered the issue of growing hydropower in three of the world’s major river basins: the Amazon, Congo, and Mekong rivers. Collectively, these basins hold approximately one-third of all freshwater fish species in the world, most of which are endemic to their respective river basin. The maintenance and sustainability of this biodiversity is threatened by the growing number of active and planned hydroelectric dams along major streams and smaller tributaries. Dams have been shown to effect the normal behavior of a river, physically trapping sediment behind it and therefore limiting nutrients further downstream, causing erosion and changing the types of available habitat for different aquatic species. From a human perspective, most local populations living along the river do not likely feel the benefits of these dams and may be displaced by the resulting reservoirs. Additionally, dams have been shown to detrimentally impact migratory fishes, even within the presence of fish passage devices. This has resulted in depletion of fish stocks which are negative for the ecosystem and hurt the local fishermen. The authors propose a holistic, basin-wide approach for the further approval and permitting of dams and suggest that greater care needs to taken during the planning phase to assess costs and benefits for all stakeholders. – Josh

Image via Allie Caulfield

Article – Balancing hydropower and biodiversity in the Amazon, Congo, and Mekong.

Citation – Winemiller, K. O., McIntyre, P. B., Castello, L., Fluet-Chouinard, E., Giarrizzo, T., Nam, S., … & Stiassny, M. L. J. (2016). Balancing hydropower and biodiversity in the Amazon, Congo, and Mekong. Science, 351(6269), 128-129.

Presenter – Josh Cullen

water-jellyfish

Jan. 20th – Does human expansion into marine environments favour jellyfish?

In this study, the authors aimed to investigate how human activities and expansion further into oceanic environments might be increasing jellyfish blooms and abundance. The authors acknowledge that certain activities, such as farming and agriculture, can increase nutrient loading along coastlines, creating nutrient rich waters that favour jellyfish growth. However, the focus of this study is how settlement behaviour of jellyfish larva has been shaped by humans via offshore oil platforms, sea walls, ship traffic, aquaculture, or other man-made structures. Collecting data and field observations from previous SCUBA studies, field experiments, and laboratory experiments yielded data that supports the argument of human infrastructure benefitting larval settlement. By placing a selection of natural and artificial substrates, jellyfish larvae were shown to preferentially choose certain artificial materials over natural materials. These results support the argument made by the authors that as we continue our exploration into the ocean, continue to build more platforms and sea walls to benefit ourselves, we are also shaping the ocean ecosystems. – Shawna 

Image via: Mike tsukunibito

Article – Is global ocean sprawl a cause of jellyfish blooms?

Citation – Duarte, C. M., Pitt, K. A., Lucas, C. H., Purcell, J. E., Uye, S. I., Robinson, K., … & Madin, L. (2013). Is global ocean sprawl a cause of jellyfish blooms?. Frontiers in Ecology and the Environment, 11(2), 91-97.

Presenter –  Shawna Little

800px-oil_platform_in_the_north_sea

Nov. 4 – Using retired oil platforms for aqua cultural purposes

This review paper discussed the costs, benefits, and challenges to establishing an open ocean aquaculture (OOA) industry in the Gulf of Mexico (GoM), with a particular focus on platform-based mariculture. There are currently over 2000 oil and natural gas structures stationed offshore along the GoM coastline, many of which are being decommissioned and removed. The decline in usage of these platforms is expected to continue, thus there is significant interest in finding alternative uses for these structures. There also exists a need for and interest in the development of an OOA industry in the GoM, which could potentially provide a sustainable food source and repurpose oil and natural gas platforms for offshore aquaculture use. However, constraints for selecting established structures make platform-based OOA unattractive to both oil and gas and mariculture operators, with liability being the greatest obstacle. Regulations hold the original oil and gas operators liable for platform removal, which is expensive and becomes more costly if the platform is damaged or destroyed by weather events such as the hurricanes that frequently occur in the GoM. The authors conclude that although OOA may eventually develop in the GoM, it is unlikely to utilize existing oil and gas platforms due to liability and site-selection issues. – Alex

Image via: Erik Christensen via WikiCommons

Article – A review of the feasibility, costs, and benefits of platform-based open ocean aquaculture in the Gulf of Mexico

Citation – Kaiser, M. J., Snyder, B., & Yu, Y. (2011). A review of the feasibility, costs, and benefits of platform-based open ocean aquaculture in the Gulf of Mexico. Ocean & coastal management54(10), 721-730.

Presenter – Alexandra

800px-east_river_valley_trophic_web

Oct. 28 – The Role of Meiofauna in river ecosystems

Meiofauna are an often-overlooked aspect of aquatic systems. Recent studies, however, have indicated that these organisms deserve much more attention and may prove important to not only the benthic community, but entire systems.

Schmid-Araya et al. (2016) used stable isotope and gust content analyses to argue that meiofauna are an important component of aquatic food webs, and when included in food-web analysis, they greatly increase the complexity and trophic links within a system.  The authors also found that meiofauna have a substantial seasonal influence on food-web/trophic structure. In the summer, meiofauna are more abundant than macrofaunal, and therefore promote longer food web interactions in the summer season, as opposed to winter when the food web is shorted due to the decrease in organisms.

In addition, stable isotope analyses indicated that meiofauna tend to belong to higher trophic levels, consuming lower-level organisms and organic biofilms. Due to their status as higher-level trophic organisms (at least in the study system), meiofauna may have a top-down influence on aquatic systems. – Marissa

Image: By Yoon, I., R.J. Williams, E. Levine, S. Yoon, J.A. Dunne, and N.D. Martinez. [FAL], via Wikimedia Commons

Article  – Trophic positioning of meiofauna revealed by stable isotopes and food-web analyses.

Citation – Schmid‐Araya, J. M., Schmid, P. E., Tod, S. P., & Esteban, G. F. (2016). Trophic positioning of meiofauna revealed by stable isotopes and food web analyses. Ecology97(11), 3099-3109.

Presenter – Marissa

sapporo_ichiban_catford_london_4073176136

Oct. 21- Investigating the use of different species of macroalgae for food and energy

As the global population continues to rise, there are growing concerns about how food demands will be met for all those people. The authors of this paper, aimed to elucidate the potential for different algal species as a nutritive food source as well as a potential energy source for those with low food applicability. Currently, there are several species of algae frequently used as food additives, common species used in sushi, and several more being investigated for the purposes of biofuel. Focused in the French Brittany, ten different species of macro algae were investigated for their nutritional values concerning mineral, lipid, protein, carbohydrate and fiber content. Additionally, the same species were analyzed for alginates, polyphenols, and methane potential. The authors found the most nutritional species for food purposes to be Palmaria palmata, Saccharina latissima was best for alginate extraction, and for methane potential, Sargassum muticum was the top species. – Shawna

Image via: By Ewan Munro from London, UK 

Article – French Brittany macroalgae screening: Composition and methane potential for potential alternative sources of energy and products.

Citation – Jard, G., Marfaing, H., Carrère, H., Delgenes, J. P., Steyer, J. P., & Dumas, C. (2013). French Brittany macroalgae screening: composition and methane potential for potential alternative sources of energy and products. Bioresource technology144, 492-498.

Presenter – Shawna

Bakterien: StŠbchenbakterien. Geobacter metallireducens
Das Bild zeigt Uran-abbauende Bakterien auf einem Schwermetall- Erz. Mikroorganismen der Gattung Geobacter kšnnen gelšstes Uran in Pechblende (Uraninit) umwandeln. Uraninit ist nicht wasserlšslich, verbleibt an Ort und Stelle und kann deshalb einfach entsorgt werden. Geobacter-Bakterien finden sich Ÿberall in Sedimenten, allerdings nur in geringer Zahl. Durch Zugabe von Acetat kšnnen sie zur Vermehrung angeregt werden. Das Verfahren soll schon bald in der Praxis angewandt werden.  Damit haben Mikrobiologen eine Mšglichkeit gefunden, uranverseuchtes Grundwasser durch Bakterien zu sŠubern.
Raster-Elektronen-Mikroskop,   3600:1

Oct. 14 – Can microbes at the sediment-water interface be used as a reliable source of energy?

Using fuel cell technology, Tender et al. provides insight into the application of harvesting electrical energy from the seafloor (2002). A voltage gradient naturally occurs between reductant-rich sediment on the seafloor and oxygen-rich seawater. Reductants such as sulfide are built up as a result of microorganisms oxidizing detrital organic carbon found within the sediment. Tender et al. sought to utilize this unique voltage gradient by placing fuel cells on the seafloor outside of Tuckerton, New Jersey and Newport, Oregon. Results suggest that the energy generated from these fuel cells remains relatively stable over time (one deployed fuel cell averaged a power density of 28 mW/m2 at 0.27 V for five months). Upon examination of microbial communities surrounding the anode, delta-Proteobacteria made up 76% of the 16S rDNA sequenced. Tender et al. suggests this power source can be used to provide energy to oceanographic equipment. – Lauren

Image via US Department of Energy

  • Article – Harnessing microbially generated power on the sea floor
  • Citation – Tender, L.M., Reimers, C.E., Stecher III, H.A., Holmes, D.E., Bond, D.R., Lowy, D.A., Pilobello, K., Fertig, S.J., & Lovley, D.R. (2002). Harnessing microbially generated power on the seafloor. Nature Biotechnology, 20, 821-825.
  • Presenter – Lauren
hurrikan-katrina-08-28-2005-1545z

Oct. 7 – Is it possible to reduce hurricanes strength while generating electricity?

As coastal populations and infrastructure continue to grow, hurricane damage is increasing in coastal regions. Jacobsen et al. (2014) propose that the installation of large arrays offshore wind turbines upwind of coastal regions will mitigate the impacts of hurricanes by reducing storm surge and wind speed of the storms before it makes landfall. Additionally, these offshore wind turbine arrays would generate large quantities of sustainable energy to address heightened energy demands of global population growth. To test this hypothesis, Jacobsen et al. (2014) modeled the impacts (wind, storm surge, and movement) of hurricanes Katrina and Sandy as both as they occurred (without offshore arrays), and again with offshore. Model output revealed that large turbine arrays could diminish peak near-surface wind speeds by 25-41 m s-1 and storm surge by 6-79%. Installation of these arrays presents high costs upfront. However, cost-benefit analysis reveals that these arrays would generate enough energy and reduce hurricane related damage enough in the long-term to actually be cheaper than the net cost of seawall installation and fossil fuel consumption in coastal regions. – Tyler

Image via US NOAA

  • Article – Taming hurricanes with arrays of offshore wind turbines
  • Citation – Jacobson, M. Z., Archer, C. L., & Kempton, W. (2014). Taming hurricanes with arrays of offshore wind turbines. Nature climate change, 4(3), 195-200.
  • Presenter – Tyler