Blue foods are highly diverse and are supported by a wide range of ecosystems, production practices, and markets. This diversity influences resiliency of aquatic food systems, their capacity to ...contribute to global food security, and the spread of knowledge and adoption of innovations. Here, trends in diversity and determinants of diversity in capture fisheries and aquaculture production were examined at the global and country level. Results show that fisheries production is more diverse than aquaculture production, and that social and economic factors appear to be as important for species diversity as biophysical factors. The diversity of fisheries is diminished when governance is weak, and this poses challenges for managing fisheries for nutrition-sensitive food production. It also illustrates the greater potential of aquaculture to address challenges related to access given that less diversity in aquaculture is created by economies of scale making food more accessible among lower income groups.
Defining sustainability goals is a crucial but difficult task because it often involves the quantification of multiple interrelated and sometimes conflicting components. This complexity may be ...exacerbated by climate change, which will increase environmental vulnerability in aquaculture and potentially compromise the ability to meet the needs of a growing human population. Here, we developed an approach to inform sustainable aquaculture by quantifying spatio‐temporal shifts in critical trade‐offs between environmental costs and benefits using the time to reach the commercial size as a possible proxy of economic implications of aquaculture under climate change. Our results indicate that optimizing aquaculture practices by minimizing impact (this study considers as impact a benthic carbon deposition ≥ 1 g C m−2 day−1) will become increasingly difficult under climate change. Moreover, an increasing temperature will produce a poleward shift in sustainability trade‐offs. These findings suggest that future sustainable management strategies and plans will need to account for the effects of climate change across scales. Overall, our results highlight the importance of integrating environmental factors in order to sustainably manage critical natural resources under shifting climatic conditions.
Defining sustainability goals is a crucial but difficult task because it often involves the quantification of multiple interrelated and sometimes conflicting components. Here, we developed an approach to inform sustainable aquaculture by quantifying spatio‐temporal shifts in critical trade‐offs between environmental costs and benefits using the time to reach the commercial size as a possible proxy of economic implications of aquaculture under climate change. Our findings suggest that future sustainable management strategies and plans will need to account for the effects of climate change across scales.
The use of microalgae to remediate raw effluent from brown crab aquaculture was evaluated by performing batch mode growth tests using separately the microalgae Chlorella vulgaris (Cv), Scenedesmus ...obliquus (Sc), Isochrysis galbana (Ig), Nannocloropsis salina (Ns), and Spirulina major (Sp). Removal efficiencies in batch growth were 100% for total nitrogen and total phosphorus for all microalgae. Chemical oxygen demand (COD) remediations were all above 72%. Biomass productivity varied from 20.9 mg L−1 day−1 (N. salina) to 146.4 mg L−1 day−1 (C. vulgaris). The two best performing algae were C. vulgaris and S. obliquus and they were tested in semi-continuous growth, reaching productivities of 879.8 mg L−1 day−1 and 811.7 mg L−1 day−1, respectively. The bioremediation of the effluent was tested with a transfer system consisting of three independent containers and compared with the use of a single container. The single container had the same capacity and received weekly the same volume of effluent as the three containers together. The remediation capacity of the 3 containers was much higher than the single one. The supplementation with NaNO3 was tested to improve the nutrient removal microalgae’ capacity, with positive results. The removal efficiencies were 100% for total nitrogen and total phosphorus and higher than 96% for COD. The obtained C. vulgaris and S. obliquus biomass were composed of 31 and 35% proteins, 6 and 8% lipids, 39 and 30% carbohydrates, respectively. The composition of these biomass suggest that it can be used as novel and sustainable ingredients in aquaculture feeds. The algal biomass of Cv and Sc were used as biostimulants in the germination of wheat and watercress, and very promising results were attained, with increases in the germination index for Cv and Sc of 175% and 48% in watercress and 84% and 98% in wheat, respectively. The biomasses of Cv and Sc were also subjected to a torrefaction process with 72.5 ± 1.7% char yields. The obtained biochars were tested as biostimulants for germination seeds (wheat and watercress) and as bio-adsorbent of dye solutions.
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•Microalgae can bioremediate 10% of the total volume every 2 days.•Semi-continuous vs batch growth productivity (880 and 146 mgL−1d−1 at 36th and 22nd).•NaNO3 supplementation improved COD remediation (Cv 90.3–97.7% and Sc 91.5–96.2%).•Chlorella vulgaris increased Germination index in 175% (watercress) and 84% (wheat).•Microalgae biochars adsorbed up to 63% of dye solutions without other treatments.
Recirculating aquaculture systems (RAS) are becoming important for aquaculture due to land and water supply limitations and due to their low environmental impact. Bacteria are important in RAS as ...their role in nutrient recycling has been the main mechanism for waste removal in these systems. Besides bacteria, the presence of microalgae can benefit the water quality through the absorption of inorganic nitrogen (ammonium and nitrate) and phosphorus from the water. However, reports on the inclusion of microalgae in RAS are very scarce. The objective of this study was to determine the effect of microalgae on water quality (total ammonia nitrogen, nitrite, nitrate and phosphate) and bacterial composition in a freshwater small‐scale RAS. A periphytic microalga, Stigeoclonium nanum, was used in this study. A rapid fingerprint analysis, denaturing gradient gel electrophoresis (DGGE), was used to determine the bacterial community composition in the water. The results showed that ammonia concentrations were not significantly different (p > 0.05) between RAS with microalgae (RAS+A) and RAS without microalgae (RAS‐A). However, nitrite, nitrate and phosphate were significantly lower in the RAS+A than the RAS‐A (p < 0.05). Pielou's evenness and Shannon diversity index of bacterial community between the treatments were not different (p > 0.05); however, the bacterial composition between the treatments was significantly different (p < 0.05).
Aquaculture activities often lead to environmental deterioration due to discharges of nutrient-rich wastewater without treatments. The present study aimed to develop a bio-green floating system ...(BFAS) to utilize excess nutrients, improve water quality, enhance plant and fish production, and minimize threats of aquaculture effluents. The floating raft system was constructed using water spinach integrated with a substrate (lava rock) to allow the development of biofilm communities, which together with the plants, improved the water quality by nutrient sequestration. Three treatments were employed for 105 days: (1) zero water exchange without BFAS (T
1
-NCT); (2) water exchange at 5-day intervals without BFAS (T
2
-PCT); (3) zero water exchange with BFAS (T
3
-BFAS). Total ammonia removal was significantly (
p
< 0.05) higher (92.4 ± 1.2%) in T
3
-BFAS compared to T
2
-PCT (89.2 ± 0.5%). The percent removal of other nutrients such as unionized ammonia, nitrite, and soluble reactive phosphorus was significantly (
p
< 0.05) higher in T
3
-BFAS compared to T
2
-PCT and the control. The T
3
-BFAS showed a significantly (
p
< 0.05) lower feed conversion ratio (FCR, 1.16 ± 0.05), higher (
p
< 0.05) specific growth rate (SGR, 3.58 ± 0.03), and better health indicators (hemato-biochemistry characteristics) compared to the other treatments. Heavy metals in T
3
-BFAS were significantly lower (
p
< 0.05) than the control and were significantly higher in roots than in the water. The findings suggested that the simple newly developed energy-free BFAS could enhance water quality, improve fish health, and optimize fish production in an aquaculture system without water exchange.
In intensive aquaculture systems, ammonia–nitrogen buildup from the metabolism of feed is usually the second limiting factor to increase production levels after dissolved oxygen. The three nitrogen ...conversion pathways traditionally used for the removal of ammonia–nitrogen in aquaculture systems are photoautotrophic removal by algae, autotrophic bacterial conversion of ammonia–nitrogen to nitrate–nitrogen, and heterotrophic bacterial conversion of ammonia–nitrogen directly to microbial biomass. Traditionally, pond aquaculture has used photoautotrophic algae based systems to control inorganic nitrogen buildup. Currently, the primary strategy in intensive recirculating production systems for controlling ammonia–nitrogen is using large fixed-cell bioreactors. This option utilizes chemosynthetic autotrophic bacteria, Ammonia Oxidizing Bacteria (AOB) and Nitrite Oxidizing Bacteria (NOB), for the nitrification of ammonia–nitrogen to nitrite–nitrogen and finally to nitrate–nitrogen. In the past several years, zero-exchange management systems have been developed that are based on heterotrophic bacteria and have been promoted for the intensive production of marine shrimp. In this third pathway, heterotrophic bacterial growth is stimulated through the addition of organic carbonaceous substrate. At high carbon to nitrogen (C/N) feed ratios, heterotrophic bacteria will assimilate ammonia–nitrogen directly into cellular protein. This paper reviews these three ammonia removal pathways, develops a set of stoichiometric balanced relationships using half-reaction relationships, and discusses their impact on water quality. In addition, microbial growth fundamentals are used to characterize production of volatile and total suspended solids for autotrophic and heterotrophic systems.
Microplastic (MP) was investigated in Zhanjiang Bay, a semi-enclosed bay in south China and famous for considerable mariculture industry, to evaluate whether mariculture activities accelerated MP ...pollution. The MP abundances ranged from 0 to 2.65 n/m3 (number/m3), showing seasonal variances with higher levels in May and September and lower levels in January. In the inner part of the bay, a significantly high MP abundance and predominance of foam were found during the oyster breeding period, and pollution sources were prone to be single and extensive. This suggested that MPs were strongly influenced by the intensive plastic products for oyster culturing, especially during breeding. Moreover, plastic cages used for culturing were the main source of MPs in the central part of the bay. By conducting statistical analysis for eight representative bays, the economic growth, social development, agriculture structure, and aquaculture development were supposed to influence the local MP pollution level.
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•MP pollution was on the moderate level in the aquaculture-dominated Zhanjiang bay.•MPs was dominated by foam during the oyster breeding period, varying seasonally.•Statistical analysis revealed that socio-economic factors had influences on MP level.
Offshore aquaculture is increasingly viewed as a mechanism to meet growing protein demand for seafood, while minimizing adverse consequences on the environment and other uses in the oceans. However, ...despite growing interest in offshore aquaculture, there appears to be no consensus as to what measures commonly define an offshore site or how effects of offshore aquaculture – relative to more nearshore practices – are assessed. This lack of agreement on what constitutes offshore aquaculture has the potential to convolute communication, create uncertainty in regulatory processes, and impede understanding of the ecological implications of offshore farming. To begin addressing these issues, we reviewed and analyzed biologically-focused primary and gray literature (Ntotal = 70) that categorize and quantify characteristics of offshore aquaculture from around the world. We found that many ‘offshore’ descriptions are relatively close to shore (< 3 nm) and significantly shallower (minimum depth ≤ 30 m) than may be assumed. We also uncovered an overall lack of consistent reporting of even the most common location-focused metrics (distance from shore, depth, current), a dearth of impact related studies (n = 17), and narrow scope of the studies themselves (i.e., 82% nutrient pollution). Of the finite subset of articles that investigated negative ecological impacts of offshore aquaculture, we found the probability of any measurable impact from an offshore farm appears to significantly decrease with distance from the farm (probability of measurable response at 90 m ± SE = 0.01 ± 0.03). Such general, but informative points of reference could be more robustly quantified with better systematic and standardized reporting of physical farm characteristics and a broader scope of ecological investigation into the effects of marine aquaculture. With offshore aquaculture still in its infancy, consistent metrics are needed for a comparable framework to guide sustainable offshore aquaculture research and development globally.
A reliable and cost‐effective source of fingerlings is essential for the successful commercial aquaculture of black sea bass. This study aimed to determine the effects of nursery tank stocking ...densities on the growth performance, feed efficiency, survival, tolerance to shipping, and biochemical quality of juvenile black sea bass. In two experiments, different stocking densities were compared for black sea bass at different stages of development. In Experiment 1, intermediate stage juveniles (1.27 g mean wt) were stocked at densities of 4.5 and 6.5 fish per liter of tank volume. Growth performance and biochemical quality were similar between the two density treatments. In Experiment 2, early post‐metamorphic stage juveniles (mean wt. = 0.524 g) were compared using the same stocking densities. While the fish reared at 4.5 fish/L were slightly larger, there were no significant differences in growth performance or biochemical quality between the density treatments. After both experiments, the fingerlings from each density treatment showed high survival rates under acute crowding and simulated shipping conditions. The study demonstrates that high NT densities of 4.5 and 6.5 fish/L did not negatively impact the growth performance and quality of black sea bass fingerlings, providing transport‐ready fingerlings in a relatively short period.
During the teleost ontogenesis, biotic and abiotic factors influence organs deformations. Despite of an important literature, the potential causes of deformities in fish are still poorly understood. ...Cultured fish in artificial conditions exhibit higher incidence of developmental impairments compared to wild ones. This study aims at describing exhaustively the deformity categories of newly hatched embryos of Eurasian perch and investigating at once all biotic and abiotic factors of two extremely different rearing systems recirculating aquaculture system (RAS) vs. ponds on their occurrence. The description and clustering of deformities according to the organs involved allowed not only to show that skeletal, cardiac and yolk anomalies are the most common ones, but also to highlight new functions undergoing developmental failure (locomotive, digestive and excretory systems). In total, 10 categories of abnormalities have been described. In addition, our data show a relationship between the cardiac and yolk deformities suggesting common causes. In a second part, we compared the incidence of deformities in the progeny of two distinct populations of fish, reared under extremely various conditions (RAS vs. pond). The total deformity rates did not differ between the groups but the nature of deformities was surprisingly different as the RAS reared fish (RRF) originating from fisheries presented a higher variety of deformity categories than the fish originating from Lorraine ponds (LPRF). Indeed, cardiac, yolk and skeletal axis deformities were more frequent in RRF embryos, whereas mouth abnormalities were preferentially represented in LPRF embryos. These findings may help understanding the potential causes of these developmental impairments in cultured animals and may lead to the improvement of husbandry conditions.
This work first aimed at characterizing exhaustively which tissues undergo important deformities during the early embryogenesis. Ten categories of deformities have thus been described. In addition, we show that populations reared in extremely different conditions ponds vs. recirculating aquaculture system (RAS) display different rates for some of these categories.
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