Description: The value of macroalgae in a healthy human diet is becoming increasingly recognized and supported throughout Europe. Macroalgae provide a rich source of vitamins, minerals, proteins, fatty acids, and antioxidants that also support the functionality of macroalgae in other industries, including cosmeceuticals, pharmaceuticals, and more recently, packaging. Sustainable aquaculture of macroalgae will be necessary to supply the increasing demand for macroalgae as a functional material, considering that natural harvests are limited and cannot keep up with demand. Different methods can be used to cultivate macroalgae, including flow-through systems or recirculating aquaculture systems (RAS) with natural or artificial seawater. The latter provides strict control over the growth conditions and water quality in order to provide a high quality and traceable product. Additionally, environmental conditions such as salinity, temperature, and light can be modified to optimize the concentration of functional ingredients in macroalgae. While most research efforts have focused on seasonal and geographic trends in concentrations of functional ingredients in wild macroalgae, there is less information available on optimizing these functional ingredients in aquaculture. Therefore, we performed controlled experiments to optimize the activity of antioxidants in Agarophyton vermiculophyllum (Ohmi) Gurgel, J.N.Norris et Fredericq comb. nov. (formerly Gracilaria vermiculophylla) grown in RAS with artificial seawater and commercial fertilizer. We show that the free radical scavenging activity could be increased by 13% via high salinity, and up to 34% by increasing the light intensity, but not daily light dose, for a period of 7 days. We also monitored growth rates and the maximum quantum yield of photosystem II (Fv/Fm) and show that the conditions for optimizing antioxidant activity are not optimal for growth or photosynthesis. We therefore suggest an optimization period of 4–7 days exposure to high light on a 6:18 hour light:dark cycle prior to harvesting in order to increase antioxidant activity.

Description: Aquaculture development in Europe, while critical to the European Union (EU) Blue Growth strategy, has stagnated over the past decades due largely to high competition for space in the nearshore coastal zone among potential uses and the lack of clear priorities, policy, and planning at EU and national scales. Broad Marine Spatial Planning, including the designation of Allocated Zones for Aquaculture, requires spatial data at the corresponding broad spatial scale, which has not been readily available, as well as model projections to assess potential impacts of climate change. Here, daily chlorophyll-a, water temperature, salinity, and current speed outputs from a marine ecosystem model encompassing the coastal North East Atlantic, the North Sea, and the Mediterranean Sea (the pan-European POLCOMS-ERSEM model configuration) are used to drive a Dynamic Energy Budget growth model of Pacific oyster (Crassostrea gigas). Areas broadly suitable for growth were identified using threshold tolerance range masking applied using the model variables mentioned above, as well as bathymetry data. Oyster growth time series were transformed into simplified indicators that are meaningful to the industry (e.g., time to market weight) and mapped. In addition to early-century indicator maps, modelling and mapping were also carried out for two contrasting late-century climate change projections, following representative concentration pathways 4.5 and 8.5. Areas found to have good oyster growth potential now and into the future were further assessed in terms of their climate robustness (i.e., where oyster growth predictions are comparable between different future climate scenarios). Several areas within Europe were highlighted as priority areas for the development of offshore Pacific oyster cultivation, including coastal waters along the French Atlantic, the southern North Sea, and western Scotland and Ireland. A large potential growth hot spot was also identified along northwestern Africa, associated with a cool, productive upwelling coastal zone. The framework proposed here offers a flexible approach to include a large range of ecological input data, climate and ecosystem model scenarios, aquaculture-related models, species of interest, indicator types, and tolerance thresholds. Such information is suggested to be included in more extensive spatial assessments and planning, along with further socioeconomic and environmental data.

Description: The investigation and application of a wide range of dietary supplements, such as probiotics, prebiotic and other additives, are increasingly popular in aquaculture research and practice. To date few studies have attempted to quantify the value of commercially available additives in improving growth performance of juvenile turbot (Scophthalmus maximus) and in compensating potential growth reduction resulting from high levels of plant protein (PP) in carnivorous fish diets. Two experiments were conducted to investigate the effect of different active ingredients in diet additives on turbot. I) Five diets supplemented with (1) yeast b-glucan and mannan oligosaccharides (GM), (2) alginic acid from brown algal extracts (AC), (3) yeast nucleotides and RNA (NR), (4) potassium diformate (PDF) and (5) bacteria strains Bacillus subtilis and B. licheniformis (BS), containing fish meal (FM) as the only protein source, were fed to turbots (initial weight 48.8 g ± 5.2 g) over 112 days. II) Four diets supplemented with (1) GM, (2) AC, (3) NR and (4) BS, containing soy protein concentrate (SPC) and wheat gluten (WG) as a partial replacement of FM, were fed to turbots (initial weight 95.8 g ± 17.7 g) over 84 days. A non-supplemented FM diet (exp. I) and an FM- and PP-based diet (exp. II), respectively, were used as control diets. Diet additives did not promote additional weight gain, specific growth rate (SGR), daily feed intake (DFI) and feed conversion ratio (FCR) in turbot fed FM- or PP-based diets (p 〉 0.05) when compared to isocaloric control diets in both experiments. Growth of turbots fed the high FM content control diet (II) was significantly higher than all other treatments (p 〈 0.01). Body proximate composition, condition factor (K) and liver index (HSI) remained unaffected by additive supplementation in fish fed either FM or PP diets (p 〉 0.05). Results indicate that reported benefits for specific diet additives cannot be assumed to function or applied across species boundaries and age classes. In addition, dietary additive application may not be economically valid for larger animals and/or animals not exposed to specific culture-related stressors. The benefits of popular additives to high value species such as S. maximus remains to be tested under specific immune or physical stress situations and at crucial larval and early juvenile stages.

Description: Technological solutions to increase the efficiency of spatial use can play a key role as part of the toolbox of marine spatial planning. Co-locating of multiple ocean uses can potentially increase the production and enjoyment of the ocean while limiting impacts. However, a basic precondition for co-locating or coproduction is that all parties' private incentives are aligned. We use a case study of co-locating an offshore wind energy firm and a mussel aquaculture firm to assess the incentive structure for cooperation and to demonstrate that social benefits from co-locating exist. We find that there is room for cooperation between firms based on potential cost sharing and that the demonstrated social benefits may arise without government intervention.