Natural Sciences

Wind Sea Algae Workshop Report

Trent DJonathan, Lange PLene, Hu PQiang, Lindblad PPeter, Averner DMel. Wind Sea Algae Workshop Report. Lolland, Denmark: International Conference on Offshore Algae for Biofuels and Beyond; 2009.
Freely available?: 
Yes
Summary available?: 
No
Type: Report

It has been known for decades that algae, in particular microalgae, have the potential to be used as a sustainable, carbon-neutral source of biofuels.1 From 1978-1996 the US Department of Energy (DOE) investigated the use of microalgae as a source of oil as well as biomass, hydrogen, hydrocarbons, alcohols, carbohydrates, methane, and syngas. This DOE algae program (The Aquatic Species Program) ended in 1996 for three reasons: 1) the DOE predicted that the cost of petroleum would remain relatively flat for at least 20 years (1996-2016), 2) that algal biodiesel could not compete with such cheap petroleum prices supported by a highly subsidized corporate infrastructure, and 3) there were many formidable technical challenges associated with growing the large quantities of algae needed for fuels. DOE was wrong about their predicted price of oil (Fig. 1).

Within three years the price of oil began to rise and within ten years it was >5 times the “flat” value the DOE had predicted. By 2009, the global reserves of petroleum are reaching their previously predicted limits,2 the largest remaining reserves of oil remain in politically unstable countries, and, most importantly, the increased burning of petroleum, impacting global climate, is of growing concern.3 Indeed, all things considered the price (in many senses) for the continued use of petroleum is too high. DOE’s prediction about the “price” of petroleum was wrong, could they also have been wrong about the economic and technical challenges preventing algae from becoming the much-needed replacement for petroleum? Considerable efforts are now underway to determine if algae can indeed be cultivated in sufficient quantities and at prices that are relevant for biofuels. Nearly all of these efforts are focused on scaling and improving traditional algae cultivation methods on land, which use shallow ponds (raceways) or large photo-bioreactors (PBRs). There are some non-traditional efforts looking into growing and harvesting algae in natural lakes and in harvesting algae directly from the ocean. Progress is being made, but to date, none of these systems have demonstrated they will be able to reach the quantities. and economics-of-scale for algae to contribute significantly to biofuels. In addition, most of the landbased methods are problematic because they significantly impact the environment--changing natural ecologies and competing for agricultural land and water. Indeed, the amount of freshwater required for replacing evaporated water in raceways and for controlling temperature in closed bioreactors, is in itself prohibitive. The goals of the Wind, Sea, and Algae workshop were to address the problems of large-scale algae cultivation on land by considering the possibilities of moving algae cultivation offshore into the ocean. More specifically, a multidisciplinary group of scientists and engineers from Universities, National Laboratories, and Industry, explored the idea of Offshore Membrane Enclosures for Growing Algae (OMEGA). Participants included experts on macro-algae (seaweeds), who provided background information from their offshore cultivation methods. We considered possibilities for ocean environments in general, and Lolland or more specifically the wind farms off the coast of Lolland, in particular. The program of the three-day workshop included lectures in the morning and breakout sessions in the afternoons. The groups discussed and debated, if offshore microalgae production is feasible, scalable, environmentally acceptable, and cost effective. Both the lectures and the breakout sessions were videotaped. This report includes transcripts of the lectures and discussions, selected and edited by the organizers. We hope this volume will help elucidate the challenges and opportunities of offshore algae cultivation and provide inspiration and guidance for future developments in this field in Lolland’s community test facility and beyond.

Effects of sea ice and wind speed on phytoplankton spring bloom in central and southern Baltic Sea

Pärn O, Lessin G, Stips A. Effects of sea ice and wind speed on phytoplankton spring bloom in central and southern Baltic Sea Anil AChandrashe. PLOS ONE [Internet]. 2021 ;16(3):e0242637. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0242637
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

In this study, the effects of sea ice and wind speed on the timing and composition of phytoplankton spring bloom in the central and southern Baltic Sea are investigated by a hydrodynamic–biogeochemical model and observational data. The modelling experiment compared the results of a reference run in the presence of sea ice with those of a run in the absence of sea ice, which confirmed that ecological conditions differed significantly for both the scenarios. It has been found that diatoms dominate the phytoplankton biomass in the absence of sea ice, whereas dinoflagellates dominate the biomass in the presence of thin sea ice. The study concludes that under moderate ice conditions (representing the last few decades), dinoflagellates dominate the spring bloom phytoplankton biomass in the Baltic Sea, whereas diatoms will be dominant in the future as a result of climate change i.e. in the absence of sea ice.

Implications of nest relocation for morphology and locomotor performance of green turtle (Chelonia mydas) hatchlings

Tanabe LK, Steenacker M, Rusli MUzair, Berumen ML. Implications of nest relocation for morphology and locomotor performance of green turtle (Chelonia mydas) hatchlings. Ocean & Coastal Management [Internet]. 2021 ;207:105591. Available from: https://www.sciencedirect.com/science/article/pii/S0964569121000764?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Sea turtle scute abnormalities are observed in higher proportion in hatchlings compared to adults, suggesting that hatchlings with a non-modal scute pattern (NMSP) have a lower chance of surviving to adulthood. In this study, we collected 732 newly emerged hatchlings from Redang Island, Malaysia, and compared their scute classification, size, and mass to fitness correlates (self-righting ability, crawling speed, and swimming speed). We investigated the proportion of hatchlings from each nest with NMSP to determine if there was a correlation with incubation duration or clutch relocation. We found relocated clutches at Chagar Hutang Turtle Sanctuary had a significantly shorter incubation duration with a higher proportion of NMSP compared to in situ clutches. Hatchlings’ mass were significantly heavier from in situ clutches compared to relocated clutches, although there were no significant differences of hatchling speed based on scute classification or clutch type. The difference of hatchling mass between in situ and relocated clutches could affect predation and mortality rates on recently emerged hatchlings. These findings have important conservation implications, suggesting that relocation should only be implemented on clutches with a high potential to be disrupted or with a low chance of survival if left in situ. Our findings highlight the need for a standard procedure when clutch relocation is used as a conservation strategy. Relocation should replicate natural nest dimensions by duplicating both nest width and depth, and clutches should be relocated to similar shade conditions as the natural nest.

Multiple Metrics of Temperature, Light, and Water Motion Drive Gradients in Eelgrass Productivity and Resilience

Krumhansl KA, Dowd M, Wong MC. Multiple Metrics of Temperature, Light, and Water Motion Drive Gradients in Eelgrass Productivity and Resilience. Frontiers in Marine Science [Internet]. 2021 ;8. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2021.597707/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1554790_45_Marine_20210216_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Characterizing the response of ecosystems to global climate change requires that multiple aspects of environmental change be considered simultaneously, however, it can be difficult to describe the relative importance of environmental metrics given their collinearity. Here, we present a novel framework for disentangling the complex ecological effects of environmental variability by documenting the emergent properties of eelgrass (Zostera marina) ecosystems across ∼225 km of the Atlantic Coast of Nova Scotia, Canada, representing gradients in temperature, light, sediment properties, and water motion, and evaluate the relative importance of different metrics characterizing these environmental conditions (e.g., means, extremes, variability on different time scales) for eelgrass bioindicators using lasso regression and commonality analysis. We found that eelgrass beds in areas that were warmer, shallower, and had low water motion had lower productivity and resilience relative to beds in deeper, cooler areas that were well flushed, and that higher temperatures lowered eelgrass tolerance to low-light conditions. There was significant variation in the importance of various metrics of temperature, light, and water motion across biological responses, demonstrating that different aspects of environmental change uniquely impact the cellular, physiological, and ecological processes underlying eelgrass productivity and resilience, and contribute synergistically to the observed ecosystem response. In particular, we identified the magnitude of temperature variability over daily and tidal cycles as an important determinant of eelgrass productivity. These results indicate that ecosystem responses are not fully resolved by analyses that only consider changes in mean conditions, and that the removal of collinear variables prior to analyses relating environmental metrics to biological change reduces the potential to detect important environmental effects. The framework we present can help to identify the conditions that promote high ecosystem function and resilience, which is necessary to inform nearshore conservation and management practices under global climate change.

Molecular Traits of Dissolved Organic Matter in the Subterranean Estuary of a High-Energy Beach: Indications of Sources and Sinks

Waska H, Simon H, Ahmerkamp S, Greskowiak J, Ahrens J, Seibert SL, Schwalfenberg K, Zielinski O, Dittmar T. Molecular Traits of Dissolved Organic Matter in the Subterranean Estuary of a High-Energy Beach: Indications of Sources and Sinks. Frontiers in Marine Science [Internet]. 2021 ;8. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2021.607083/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1554790_45_Marine_20210216_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Advective flows of seawater and fresh groundwater through coastal aquifers form a unique ecohydrological interface, the subterranean estuary (STE). Here, freshly produced marine organic matter and oxygen mix with groundwater, which is low in oxygen and contains aged organic carbon (OC) from terrestrial sources. Along the groundwater flow paths, dissolved organic matter (DOM) is degraded and inorganic electron acceptors are successively used up. Because of the different DOM sources and ages, exact degradation pathways are often difficult to disentangle, especially in high-energy environments with dynamic changes in beach morphology, source composition, and hydraulic gradients. From a case study site on a barrier island in the German North Sea, we present detailed biogeochemical data from freshwater lens groundwater, seawater, and beach porewater samples collected over different seasons. The samples were analyzed for physico-chemistry (e.g., salinity, temperature, dissolved silicate), (reduced) electron acceptors (e.g., oxygen, nitrate, and iron), and dissolved organic carbon (DOC). DOM was isolated and molecularly characterized via soft-ionization ultra-high-resolution mass spectrometry, and molecular formulae were identified in each sample. We found that the islands’ freshwater lens harbors a surprisingly high DOM molecular diversity and heterogeneity, possibly due to patchy distributions of buried peat lenses. Furthermore, a comparison of DOM composition of the endmembers indicated that the Spiekeroog high-energy beach STE conveys chemically modified, terrestrial DOM from the inland freshwater lens to the coastal ocean. In the beach intertidal zone, porewater DOC concentrations, lability of DOM and oxygen concentrations, decreased while dissolved (reduced) iron and dissolved silicate concentrations increased. This observation is consistent with the assumption of a continuous degradation of labile DOM along a cross-shore gradient, even in this dynamic environment. Accordingly, molecular properties of DOM indicated enhanced degradation, and “humic-like” fluorescent DOM fraction increased along the flow paths, likely through accumulation of compounds less susceptible to microbial consumption. Our data indicate that the high-energy beach STE is likely a net sink of OC from the terrestrial and marine realm, and that barrier islands such as Spiekeroog may act as efficient “digestors” of organic matter.

Resource Partitioning Between Phytoplankton and Bacteria in the Coastal Baltic Sea

Sörenson E, Farnelid H, Lindehoff E, Legrand C. Resource Partitioning Between Phytoplankton and Bacteria in the Coastal Baltic Sea. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.608244/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1495887_45_Marine_20201201_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Eutrophication coupled to climate change disturbs the balance between competition and coexistence in microbial communities including the partitioning of organic and inorganic nutrients between phytoplankton and bacteria. Competition for inorganic nutrients has been regarded as one of the drivers affecting the productivity of the eutrophied coastal Baltic Sea. Yet, it is unknown at the molecular expression level how resources are competed for, by phytoplankton and bacteria, and what impact this competition has on the community composition. Here we use metatranscriptomics and amplicon sequencing and compare known metabolic pathways of both phytoplankton and bacteria co-occurring during a summer bloom in the archipelago of Åland in the Baltic Sea to examine phytoplankton bacteria resource partitioning. The expression of selected pathways of carbon (C), nitrogen (N), and phosphorus (P) metabolism varied over time, independently, for both phytoplankton and bacteria, indicating partitioning of the available organic and inorganic resources. This occurs regardless of eukaryotic plankton growth phase (exponential or stationary), based on expression data, and microbial community composition. Further, the availability of different nutrient resources affected the functional response by the bacteria, observed as minor compositional changes, at class level, in an otherwise taxonomically stable bacterial community. Resource partitioning and functional flexibility seem necessary in order to maintain phytoplankton-bacteria interactions at stable environmental conditions. More detailed knowledge of which organisms utilize certain nutrient species are important for more accurate projections of the fate of coastal waters.

 

Feeding Habits of Bigeye Tuna (Thunnus obesus) in the Western Indian Ocean Reveal a Size-Related Shift in Its Fine-Scale Piscivorous Diet

Lin C-H, Lin J-S, Chen K-S, Chen M-H, Chen C-Y, Chang C-W. Feeding Habits of Bigeye Tuna (Thunnus obesus) in the Western Indian Ocean Reveal a Size-Related Shift in Its Fine-Scale Piscivorous Diet. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.582571/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1495887_45_Marine_20201201_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

This study analyzed the piscivorous diet of bigeye tuna (Thunnus obesus) through species identification of both fish and otolith remains in stomachs of 183 bigeye tuna collected in the western Indian Ocean. A total of 642 fish remains and 1,021 fish otoliths were examined. Prey items identified in the fish and otolith remains were not completely consistent. Although 12 items out of the 53 identified taxa were found in both remains, 20 items of fish remains were not found in otolith remains, and 21 items were added only from the otoliths. The main fish remains were Alepisauridae, which accounted for 13.9%. Most of the otoliths belonged to Myctophidae (49.5%) and Scopelarchidae (21.4%). Three prey items, namely Valenciennellus tripunctulatusEvermannella sp., and Zenion sp., were recorded for the first time in the diet of bigeye tuna from the region. The otolith remains substantially enhanced the taxonomic resolution of the diet. Bigeye tuna stomach contents were independent of location, depth, and time of catch but varied with tuna size. The proportion of dominant Myctophidae prey items decreased markedly as the tuna size increased, whereas the proportion of Macrouridae increased with size. In addition, larger bigeye tuna were found feeding on larger prey (Electrona risso and Scopelarchus analis), demonstrating that diet changes in both prey composition and size are related to the ontogeny of the fish.

Climatic and Oceanographic Controls on Coral Bleaching Conditions in the Maldivian Region

De Falco C, Bracco A, Pasquero C. Climatic and Oceanographic Controls on Coral Bleaching Conditions in the Maldivian Region. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.539869/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1495887_45_Marine_20201201_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

The frequency of coral bleaching events has been increasing in recent decades due to the temperature rise registered in most regions near the ocean. Their occurrence in the Maldivian Archipelago has been observed in the months following the peak of strong El Niño events. Bleaching has not been uniform, and some reefs have been only marginally impacted. Here, we use satellite observations and a regional ocean model to explore the spatial and temporal variability of sea surface temperatures (SSTs), and quantify the relative magnitude of ENSO-related episodes with respect to the recent warming. In line with other studies, it is confirmed that the long-term trend in SST significantly increases the frequency of stress conditions for the Maldivian corals. It is also found that the interaction between currents and the steep bathymetry is responsible for a local cooling of about 0.2°C in the Archipelago during the warmest season, with respect to the surrounding waters. This cooling largely reduces the frequency of mortality conditions.

Complex Interactions of Temperature, Light and Tissue Damage on Seagrass Wasting Disease in Zostera marina

Jakobsson-Thor S, Brakel J, Toth GB, Pavia H. Complex Interactions of Temperature, Light and Tissue Damage on Seagrass Wasting Disease in Zostera marina. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.575183/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1467818_45_Marine_20201027_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

The temperate seagrass species eelgrass Zostera marina can be infected by the wasting disease pathogen Labyrinthula zosterae, which is believed to have killed about 90% of the seagrass in the Atlantic Ocean in the 1930s. It is not known why this opportunistic pathogen sometimes becomes virulent, but the recurrent outbreaks may be due to a weakening of the Z. marina plants from adverse environmental changes. This study investigated the individual and interactive effects of multiple extrinsic factors (temperature, light, and tissue damage) on the host-pathogen interaction between Z. marina and L. zosterae in a fully crossed infection experiment. The degree of infection was measured as both lesion coverage and L. zosterae cell concentration. We also investigated if the treatment factors affect the chemical defense of the host, measured as the inhibitory capacity of seagrass extracts in bioassays with L. zosterae. Finally, gene expression of a set of targeted genes was quantified in order to investigate how the treatments change Z. marina’s response to infection. Light had a pronounced effect on L. zosterae infection measured as lesion coverage, where reduced light conditions increased lesions by 35%. The response to light on L. zosterae cell concentration was more complex and showed significant interaction with the temperature treatment. Cell concentration was also significantly affected by physical damage, where damage surprisingly resulted in a reduced cell concentration of the pathogen. No treatment factor caused detectable decrease in the inhibitory capacity of the seagrass extracts. There were several interactive effects between L. zosterae infection and the treatment factors on Z. marina growth, and on the expression of genes associated with immune defense, phenol synthesis and primary metabolism, showing that the molecular reaction toward L. zosterae infection depends on prevailing environmental conditions. Our study shows that individual or interactive effects of light, temperature and tissue damage can affect multiple aspects of host-pathogen interactions in seagrasses. These results highlight the complexity of marine host-pathogen systems, showing that more multi-factorial investigations are needed to gain a better understanding of disease in marine plants under different environmental conditions.

Extreme Effects of Extreme Disturbances: A Simulation Approach to Assess Population Specific Responses

Reed J, Harcourt R, New L, Bilgmann K. Extreme Effects of Extreme Disturbances: A Simulation Approach to Assess Population Specific Responses. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.519845/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1467818_45_Marine_20201027_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

In South Australia, discrete populations of bottlenose dolphins inhabit two large gulfs, where key threats and population estimates have been identified. Climate change, habitat disturbance (shipping and noise pollution), fishery interactions and epizootic events have been identified as the key threats facing these populations. The Population Consequences of Disturbance (PCoD) framework has been developed to understand how disturbances can influence population dynamics. We used population estimates combined with population specific bioenergetics models to undertake a partial PCoD assessment, comparing how the two populations respond to the identified regional threats. Populations were modeled over a 5 year period looking at the influence of each disturbance separately. As expected, the most extreme epizootic and climate change disturbance scenarios with high frequency and intensity had the biggest influence on population trends. However, the magnitude of the effect differed by population, with Spencer Gulf showing a 43% and Gulf St Vincent a 23% decline under high frequency and high impact epizootic scenarios. Epizootic events were seen to have the strongest influence on population trends and reproductive parameters for both populations, followed by climate change. PCoD modeling provides insights into how disturbances may affect different populations and informs management on how to mitigate potential effects while there is still time to act.

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