A meta‐analysis of integrated multitrophic aquaculture: extractive species growth is most successful within close proximity to open‐water fish farms

In real-world situations, marine fish farms accommodate multiple fish species and cohorts within the farm, leading to diverse farm layouts influenced by cage dimensions, configurations, and intricate arrangements. These cage management practices are essential to meet production demands, however, farm-level complexities can impact model predictions of waste deposition and benthic impact near fish cages. This is of particular importance when the cages are used for integrated multi-trophic aquaculture (IMTA) with benthic feeders, where this waste not only affects environmental conditions but also provides a potential food source. The Cage Aquaculture Particulate Output and Transport (CAPOT) model incorporated multiple species, cohorts, and cage arrangements to estimate waste distribution from a commercial fish farm in the Mediterranean between October 2018 and July 2019. This spreadsheet model estimated dispersion for individual fish cages using a grid resolution of 5 m x 5 m. The study categorized discrete production periods for each fish cage every month, aligning with intermittent changes in biomass and food inputs due to different cage management practices throughout production. This approach facilitated the use of detailed input data and enhanced model representativeness by considering variations in cage biomass, food types, settling velocities, and configurations. Model outputs, represented in contour plots, indicated higher deposition directly below fish cages that varied monthly throughout fish production cycles. Deposition footprints reflected changes in cage biomass, food inputs, and farm-level practices reflecting this real-world scenario where aquaculture does not follow a production continuum. Moreover, cohort dynamics and cage movements associated with the cage management practices of the fish farm influenced the quantity and fate of wastes distributed around fish cages, revealing variability in deposition footprints. Clearly, these findings have important implications for the design of benthic IMTA systems, with species such as sea cucumber and polychaetes. Variability in waste deposition creates challenges in identifying where the benthic organisms should be placed to allow optimal uptake of waste to meet their food requirements and increase survivability. Evidently, models have an important role to play and this study emphasizes the need for representative input data to describe actual food inputs, cage biomass changes, and management practices for more representative farm-scale modelling and essentially to improve particulate waste management. To effectively mitigate benthic impacts through IMTA, models must quantify and resolve particulate waste distribution and impact around fish farms to maintain a balanced system with net removal of wastes. Resolving farm-level complexities provides vital information about the variability of food availability and quality for extractive organisms that helps improve recycling of organic wastes in integrated systems, demanding a more representative modelling approach.

Stable isotope ratios, carbon (δ13C) and nitrogen (δ15N), and fatty acids validated the trophic connection between farmed fish in a commercial nearshore fish farm and sea cucumbers in the Mediterranean Sea. This dual tracer approach evaluated organic matter transfer in integrated multi-trophic aquaculture (IMTA) and the ability of sea cucumbers to incorporate fish farm waste (fish faeces and uneaten artificial fish feed) into their tissue. Between October 2018 and September 2019, Holothuria (Roweothuria) poli Delle Chiaje, 1824, co-cultured at IMTA sites directly below one of the commercial fish cage , at 10m and 25m from the selected fish cage, and at two reference sites over 800m from the fish farm. Sea cucumbers were sampled from each site in February, May and September, except at 0m due to mass mortalities recorded here in the first month of study. Isotopic mixing models revealed that fish farm organic waste was the dominant dietary source for H. poli in IMTA at 10m and 25m from the cage. The contribution of marine plant-derived organic matter, Posidonia oceanica leaves and rhizomes, was least important. The isotopic signatures of sea cucumber tissues at reference sites were not explained by the sampled food resources. Importantly, fatty acid profiling revealed a high abundance of individual terrestrial plant fatty acids, such as oleic (18:1n-9), linoleic (18:2n-6) and eicosenoic (20:1n-9) acids in sea cucumber tissue at 10m and 25m from the fish cage, presumably linked to the terrestrial plant oil content of the fish feeds. At the reference sites, sea cucumber tissues were characterised by higher relative abundance of arachidonic acid (20:4n-6) acid, and the natural marine-based eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids. These analyses revealed important differences in the composition of H. poli between the IMTA and reference locations, driven by aquaculture-derived waste near fish cages. Moreover, this study revealed temporal variation in food availability and quality, and possible differences in the physiological responses of H. poli. Stable isotope analysis and fatty acid profiling provided complementary evidence for the important dietary preferences of H. poli and validated the potential of sea cucumbers to uptake aquaculture organic waste as part of inshore fish-sea cucumber IMTA. It reveals the important implications that an established trophic link has on the viability of using sea cucumbers for the development of IMTA and the sustainable expansion of aquaculture.

Searching strategy of the painted turtle Chrysemys picta across spatial scales

Culturing the sea cucumber Holothuria poli in open-water integrated multi-trophic aquaculture at a coastal Mediterranean fish farm

Summary1. Numerous interacting abiotic and biotic factors influence niche use and assemblage structure of freshwater fishes, but the strength of each factor changes with spatial scale. Few studies have examined the role of interspecific competition in structuring stream fish assemblages across spatial scales. We used field and laboratory approaches to examine microhabitat partitioning and the effect of interspecific competition on microhabitat use in two sympatric stream fishes (Galaxias‘southern’ and Galaxias gollumoides) at large (among streams and among sites within streams) and small (within artificial stream channels) spatial scales.2. Diurnal microhabitat partitioning and interspecific competition at large spatial scales were analysed among three sympatry streams (streams with allotopic and syntopic sites; three separate catchments) and four allopatry streams (streams with only allotopic sites; two separate catchments). Electro‐fishing was used to sample habitat use of fishes at 30 random points within each site by quantifying four variables for each individual: water velocity, depth, distance to nearest cover and substratum size. Habitat availability was then quantified for each site by measuring those variables at each of 50 random points. Diet and stable isotope partitioning was analysed from syntopic sites only. Diel cycles of microhabitat use and interspecific competition at small spatial scales were examined by monitoring water velocity use over 48 h in artificial stream channels for three treatments: (i) allopatric G. ‘southern’ (10 G. ‘southern’); (ii) allopatric G. gollumoides (10 G. gollumoides) and (iii) sympatry (five individuals of each species).3. One hundred and ninety‐four G. ‘southern’ and 239 G. gollumoides were sampled across all seven streams, and habitat availability between the two species was similar among all sites. Galaxias‘southern’ utilised faster water velocities than G. gollumoides in both the field and in channel experiments. Both species utilised faster water velocities in channels at night than during the day. Diet differences were observed and were supported by isotopic differences (two of three sites). No interspecific differences were observed for the other three microhabitat variables in the field, and multivariate habitat selection did not differ between species. Interspecific competition had no effect on microhabitat use of either species against any variable either in the field (large scale) or in channels (small scale).4. The results suggest that niche partitioning occurs along a subset of microhabitat variables (water velocity use and diet). Interspecific competition does not appear to be a major biotic factor controlling microhabitat use by these sympatric taxa at any spatial scale. The results further suggest that stream fish assemblages are not primarily structured by biotic factors, reinforcing other studies de‐emphasising interspecific competition.

Soil leakage in karst areas is an important geomorphic agent of environmental interest. There are several viewpoints concerning soil leakage ratios. One viewpoint states that the soil leakage ratio is high in karst regions, whereas others consider that it is very low. This paper’s objective is to describe the soil leakage phenomena qualitatively and quantitatively in the Chongqing Karst, China, by conventional methods such as monitoring runoff plots and paint traces drawn on piles and walls found within runoff plots, and by measuring the activity of the isotope 137Cs at small, medium, and large spatial scales. This paper’s results show that soil-filled karst cracks occurred at a small spatial scale with soil leakage ratios ranging from about 3% to about 34% at two abandoned quarries and six soil profiles with rock (karst) crack development. The soil leakage ratio was almost zero at the medium spatial scale. The soil leakage ratio was 4.50% and the surface-soil erosion ratio was 95.50% of the total soil erosion at the large spatial scale. It is concluded that soil leakage ratios in the study area were low at a large spatial scale, and that cracks in karst were filled with soil at small spatial scales. This paper’s results indicate that soil leakage phenomena vary depending on the processes acting at the small, medium, and large spatial scales.

Statewide surveys of furbearers in Illinois indicate gray (Urocyon cinereoargenteus) and red (Vulpes vulpes) foxes have experienced substantial declines in relative abundance, whereas other species such as raccoons (Procyon lotor) and coyotes (Canis latrans) have exhibited dramatic increases during the same time period. The cause of the declines of gray and red foxes has not been identified, and the current status of gray foxes remains uncertain. Therefore, I conducted a large-scale predator survey and tracked radiocollared gray foxes from 2004 to 2007 in order to determine the distribution, survival, cause-specific mortality sources and land cover associations of gray foxes in an urbanized region of northeastern Illinois, and examined the relationships between the occurrence of gray fox and the presence other species of mesopredators, specifically coyotes and raccoons. Although generalist mesopredators are common and can reach high densities in many urban areas their urban ecology is poorly understood due to their secretive nature and wariness of humans. Understanding how mesopredators utilize urbanized landscapes can be useful in the management and control of disease outbreaks, mitigation of nuisance wildlife issues, and gaining insight into how mesopredators shape wildlife communities in highly fragmented areas. I examined habitat associations of raccoons, opossums (Didelphis virginiana), domestic cats (Felis catus), coyotes, foxes (gray and red), and striped skunks (Mephitis mephitis) at multiple spatial scales in an urban environment. Gray fox occurrence was rare and widely dispersed, and survival estimates were similar to other studies. Gray fox occurrence was negatively associated with natural and semi-natural land cover types. Fox home range size increased with increasing urban development suggesting that foxes may be negatively influenced by urbanization. Gray fox occurrence was not associated with coyote or raccoon presence. However, spatial avoidance and mortality due to coyote predation was documented and disease was a major mortality source for foxes. The declining relative abundance of gray fox in Illinois is likely a result of a combination of factors. Assessment of habitat associations indicated that urban mesopredators, particularly coyotes and foxes, perceived the landscape as relatively homogeneous and that urban mesopredators interacted with the environment at scales larger than that accommodated by remnant habitat patches. Coyote and fox presence was found to be associated with a high degree of urban development at large and intermediate spatial scales. However, at a small spatial scale fox presence was associated with high density urban land cover whereas coyote presence was associated with urban development with increased forest cover. Urban habitats can offer a diversity of prey items and anthropogenic resources and natural land cover could offer coyotes daytime resting opportunities in urban areas where they may not be as tolerated as smaller foxes. Raccoons and opossums were found to utilize moderately developed landscapes with interspersed natural and semi-natural land covers at a large spatial scale, which may facilitate dispersal movements. At intermediate and small spatial scales, both species were found to utilize areas that were moderately developed and included forested land cover. These results indicated that raccoons and opossums used natural areas in proximity to anthropogenic resources. At a large spatial scale, skunk presence was associated with highly developed landscapes with interspersed natural and semi-natural land covers. This may indicate that skunks perceived the urban matrix as more homogeneous than raccoons or opossums. At an intermediate spatial scale skunks were associated with moderate levels of development and increased forest cover, which indicated that they might utilize natural land cover in proximity to human-dominated land cover. At the smallest spatial scale skunk presence was associated with forested land cover surrounded by a suburban matrix. Compared to raccoons and opossums, skunks may not be tolerated in close proximity to human development in urban areas. Domestic cat presence was positively associated with increasingly urbanized and less diverse landscapes with decreased amounts of forest and urban open space at the largest spatial scale. At an intermediate spatial scale, cat presence was associated with a moderate degree of urban development characterized by increased forest cover, and at a small spatial scale cat presence was associated with a high degree of urbanization. Free-ranging domestic cats are often associated with human-dominated landscapes and likely utilize remnant natural habitat patches for hunting purposes, which may have implications for native predator and prey species existing in fragmented habitat patches in proximity to human development.

We questioned the different interpretations of ecological sexual segregation from a novel perspective, i.e., by carrying out diverse temporal and spatial scale analyses within a long-term study (1984–2003). Thus we combined spatial (small/large) and temporal (small/large) scale analyses to identify the factors generating sexual segregation in fallow deer in San Rossore, Italy. The study site was divided into an eastern sector characterized by human disturbance (DS) and a western undisturbed sector (US). According to census data, human presence increased in DS from 1984, and while females gradually abandoned it, males remained—thus supporting the predation risk hypothesis (large spatial and temporal scale)—and actually increased their presence in DS, where they seemingly benefited from a lower female density. This supported the indirect competition hypothesis. The analysis of data on a large temporal and small spatial scale confirmed that intersexual competition, in particular for grass, was higher in a crowded pasture in US. Observations by means of radio-telemetry of 23 adult females and 25 adult males (1997–2001, reduced temporal and large spatial scale) showed that large scale segregation was relevant during the day and disappeared at night, when disturbance was absent and also the females reached DS. This also supported the predation risk hypothesis. Moreover, sexes showed different habitat choices inside DS at night, thus supporting the forage selection hypothesis (small spatial and temporal scale). In conclusion, failure to address the whole set of combinations of spatial and temporal scale analyses would have led to monocausal explanations of ecological sexual segregation.

Integrated multi-trophic aquaculture of red drum (Sciaenops ocellatus) and sea cucumber (Holothuria scabra): Assessing bioremediation and life-cycle impacts

Integrated multitrophic aquaculture (IMTA) is an innovative mariculture methodology that reduces the environmental footprint and increases the profitability of the farm. It combines the cultivation of species belonging to different trophic levels, simulating a natural food web. In this study, five Mediterranean species were co-cultured in three operating fish farms in the Aegean (E. Mediterranean) Sea with different trophic conditions. The co-cultivated species were sea bream (Sparus aurata), European sea bass (Dicentrarchus labrax), Mediterranean mussel (Mytilus galloprovincialis), rayed pearl oyster (Pinctada imbricata radiata), and sea cucumber (Holothuria polii). Bream, bass, and mussels were cultivated according to the traditional on-growing methods (fish cages and longlines), whereas the pearl oysters and sea cucumbers were cultivated in baskets designed specifically for oyster farms. To estimate the growth of the co-cultivated species, growth indicators were calculated using length and weight measurements. Furthermore, the growth measurements from co-cultivated species were compared to the respective ones from natural populations. All the species showed high survival rates in the integrated multitrophic aquaculture (IMTA) conditions. Pearl oysters and Mediterranean mussels had positive growth in fish farms with high concentrations of nutrients. Mussel condition index (CI) was 42% in Aquaculture 1 (Aq1) and 33% in Aquaculture 2 (Aq2), compared to 35% in a typical Mediterranean mussel farm. Pearl oysters CI in Aq1 was 53%, in Aq2 56%, in Aquaculture 3 (Aq3) 19%, and in natural populations ranging from 30% to 45%. In contrast, holothurians did not gain weight under the fish cage regime despite the high survival rate. Their final total weight was 17.3 g in Ag1, 8.3 g in Aq2, and 18.3 g in Aq3, but in the natural population, the mean weight was 80 g.

Seasonal and ontogenetic patterns of habitat use in coral reef fish juveniles

Increasing urbanization poses significant challenges to the mental health of urban populations. Urban green spaces are known to support mental well-being by reducing stress, promoting physical activity, and fostering social interaction. However, empirical evidence on the relationship between green infrastructure and mental health remains inconsistent, partly due to methodological differences, study area characteristics and spatial scales. In selected districts of two German cities, a random sample was drawn from the local population registers, with 2,157 residents providing georeferenced residential data for the analysis. The association between greenness, measured by the Normalized Difference Vegetation Index (NDVI), and mental wellbeing, assessed using the WHO-5 Well-Being Index (WHO-5), was examined at neighbourhood level across different spatial scales. Sociodemographic factors such as gender, age, and monthly net household income were included. The mean WHO-5 score in the sample was 14.52 (SD: 4.78). NDVI values typically ranged from around 0.17 at small scales (10-25 m) to around 0.28 at larger scales (700-1,000 m). A significant association was found between NDVI and WHO-5 at small spatial scales (β = 2.97 at 10 m; β = 2.42 at 25 m) and again at larger scales (β = 2.18 at 700 m; β = 3.26 at 1,000 m), but no significant associations were observed at intermediate spatial scales (50-600 meters), with coefficients ranging from 0.30 to 1.72 and no consistent pattern. This suggests a U-shaped relationship between spatial scale and effect strength. The results indicate that while the NDVI and sociodemographic data provides valuable insights, they do not fully capture the complexity of human-environment interactions. Future studies should consider incorporating qualitative data, such as individual experiences and perceptions of green space quality, to deepen the understanding of the relationship between green infrastructure and mental health. Key messages • Mental well-being is linked to greenness at very small and large spatial scales, showing a U-shaped relationship. • Combining NDVI with additional variables provides a more comprehensive understanding of the impact of green spaces on mental well-being.

Technical feasibility of integrating Amazon river prawn culture during the first phase of tambaqui grow-out in stagnant ponds, using nutrient-rich water

Abstract: World aquaculture has been growing sharply in recent decades and Brazilian production of fish in cages has grown considerably since the end of the 1990s. This increase is related to the development of federal government regulations and the large number of medium and large hydroelectric reservoirs. The main areas of fish production in cages in Brazil are currently located in the Northeast and Southeast regions and along the Southeast/South border. Tilapia production in cages in Brazil, as well as other species produced in cages in other regions of the world, has economic advantages for the producer. On the other hand, limnologically, tilapia production in cages causes enormous damage, as it promotes the process of artificial eutrophication and, possibly, introduces this exotic species. One way of reducing artificial eutrophication is the use of Integrated Multi-trophic Aquaculture (IMTA); however, its use in fish cages installed in Brazilian reservoirs is not possible yet. Therefore, our view is that government agencies restrict the production of fish in cages to the utmost.

Present study was aimed at examining the effects of spatial scale, plant identity and management on the relationship between diversity and productivity in an old semi-natural grassland in the Solling uplands, Germany. The study was conducted in the framework of the Grassland Management (GrassMan) experiment which is a part of the Excellence cluster „Functional Biodivesity Research“ at the University of Goettingen. The experimental field is a Lolio-cynosuretum semi-natural permanent grassland with more than a hundred-year old history of extensive agricultural use. The three experimental factors (sward composition, fertilization and cutting frequency) results in 12 different treatments and are set in Latin Rectangle, comprising 6 replications of each treatment. Experimental approach that we used, the so called „removal experiment“, is aimed at studying the effects of removal itself and recovery of the vegetation after disturbance, as well as the different aspects of ecosystem functioning
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\nIn the first chapter we investigate the effects of sampling scale on the relationship between species diversity and productivity. So far, many observational studies, conducted in semi-natural grasslands, explored the relationship between species diversity and productivity at the common size of vegetation surveys of 1 m² or larger, selected according to the species minimum areal. Experimental studies, on the other hand, referred to the small-scale effects of diversity and productivity relationship which often caused the problem of extrapolating and generalizing of their results to more natural plant communities. We studied the effects of spatial scale on the biomass production and diversity relationship by selecting four spatial scales: small (0.04 m² and 0.16 m²), medium (1 m²), large (9 m²), and very large (225 m²) and comparing the power of this relationship, including the effects of agricultural management. We found that the relationship between diversity and productivity of a semi-natural grassland differed across the scales of sampling and that harvesting of the biomass at small spatial scales did not always fully reflect the relationship between the two variables (which often turned into insignificant at larger spatial scales). The most common size of plots for vegetation surveys, being 1 m², in this study showed high variation, both in vegetation composition and harvested biomass. Management system established at the field seemed to play a role in the direction of this relationship (positive or negative). So, plots cut three times a year, becoming more homogeneous (more even) in vegetation composition showed a positive relationship between diversity and productivity. We suggest that selecting an appropriate spatial scale is therefore very important in heterogeneous natural grasslands, also those agriculturally managed. While in more homogeneous environments rather small spatial scale is adequate for describing the composition and many aspects of ecosystem functioning, in more heterogeneous habitats it is important to include this parameter in the analysis.
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\nIn the second chapter we present the results of a study on the effects of management intensification in a permanent grassland and the response of overall and dominant species diversity. A removal experiment in the Solling uplands, Germany (three sward types: control, dicot-reduced and monocot-reduced) employed four different levels of management intensity resulting from a combination of two factors: fertilization (no and 180-30-100 kg ha -1 year -1 of N-P-K, respectively) and cutting frequency (cut once and three times a year). This study was conducted over two years (2010, 2011), starting with a third year after introducing the management treatments. We defined species diversity by species number per plot as well as evenness and identified dominant species, making up about 80% share of the yield. We collected information on several plant functional traits for each of the dominant species: plant height, leaf dry matter content, stem dry matter content, leaf specific area, green leaves / total leaves ratio, stem specific density, and calculated additionally the ratio of stem specific density and plant height. Further measures of functional diversity included functional group shares, functional diversity index, defined as the total branch length of the traits-species cluster diagram, and aggregated plant functional traits for each plot. We found that management intensification did not affect the total species number, but affected species evenness and functional diversity of dominant species, including their number and identity. Correlations of above-ground biomass and several dominant species’ traits were responsible for fertilization effects on above-ground productivity in this grassland. This indicates the importance of monitoring not only species richness but also other measures of diversity, as well as including management aspects in studies of plant functional traits in grasslands. 
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\nIn the third chapter of the thesis we present the results from the whole investigation period and summarize the findings of the GrassMan experiment regarding the relationship between species richness and productivity, as well as the changes in species number over time and the main determinants of productivity. We analyzed the overall effects of species diversity expressed in species number, functional group composition and species identity effects on the above-ground biomass production. We found that the effects of species richness on the productivity were rather weak while the functional group diversity was a better predictor of productivity in some years. Intensifying the management, however, caused higher above-ground biomass production. It also affected species composition and evenness: increasing cutting frequency increased the evenness while increasing fertilization decreased it. We suggest that functional group richness might be important for better use of available resources. We conclude that existing species composition under appropriate agricultural management seems to have a potential for sustainable forage production without significant species losses, when not used and fertilized too intensively, and without the need of being converted to arable land or manipulating the species composition. The changes in species diversity should, however, be monitored, including not only species number but also other parameters, such as vegetation composition and functional group shares. 
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\nWe finally discuss that our findings do not necessarily support the evidence from experimental studies on sown grasslands which often found that species richness had a defining role in biomass production. While overall species richness was of relatively less importance than management in this grassland, species composition was changing beyond just the number of species. We thus underline the importance of bringing biodiversity experiments to the „real-world“ ecosystems and suggest that thorough consideration of spatial aspects of the diversity-productivity relationship, as well as incorporating multiple measures of diversity in the experiments, conducted in agricultural grasslands under appropriate management strategies, might give better insights in their functioning and serve as motivation for farmers to conserve existing species diversity. Apart from the number of important ecosystem functions, providing fodder for herbivores and ruminants, conserving natural vegetation composition contributes to delivering further ecosystem services, which could support cultural and biodiversity benefits of the agricultural landscapes.