Temperature toleranceof the sea cucumber Holothuria scabra : towards a systematic understanding of multi-level temperature effects

The Sea cucumber Holothuria scabra significantly to the release and recycling of nutrients in tropical coastal ecosystems. Besides its fundamental ecological role, the dried body wall of H. scabra, known as Trepang or Beche-de-mer, is ranked among the highest priced global trade commodities from the ocean. The consequential overexploitation of H. scabra brought the artificial rearing of this species in the center of interest, especially in regions of the Global South. Nowadays, H. scabra has become a key species in community-based aquaculture. Temperature is the key environmental factor that determines biological fitness of H. scabra and thus aquaculture production efficiency. Hence, a detailed understanding of temperature effects on H. scabra are important in two different ways: 1) to determine the optimal thermal range and delimiting critical temperature levels for best aquaculture practices; 2) to predict the susceptibility of H. scabra to future global warming scenarios. This thesis aims to provide first insights into a mechanistic understanding of how temperature affects H. scabra at different biological organization levels

Aquaculture governance: five engagement arenas for sustainability transformation

A greater focus on governance is needed to facilitate effective and substantive progress toward sustainability transformations in the aquaculture sector. Concerted governance efforts can help move the sector beyond fragmented technical questions associated with intensification and expansion, social and environmental impacts, and toward system-based approaches that address interconnected sustainability issues. Through a review and expert-elicitation process, we identify five engagement arenas to advance a governance agenda for aquaculture sustainability transformation: (1) setting sustainability transformation goals, (2) cross-sectoral linkages, (3) land–water–sea connectivity, (4) knowledge and innovation, and (5) value chains. We then outline the roles different actors and modes of governance can play in fostering sustainability transformations, and discuss action items for researchers, practitioners, and policymakers to operationalize activities within their engagement arenas

Temperaturtoleranz der Seegurke Holothuria scabra

The Sea cucumber Holothuria scabra significantly to the release and recycling of nutrients in tropical coastal ecosystems. Besides its fundamental ecological role, the dried body wall of H. scabra, known as Trepang or Beche-de-mer, is ranked among the highest priced global trade commodities from the ocean. The consequential overexploitation of H. scabra brought the artificial rearing of this species in the center of interest, especially in regions of the Global South. Nowadays, H. scabra has become a key species in community-based aquaculture. Temperature is the key environmental factor that determines biological fitness of H. scabra and thus aquaculture production efficiency. Hence, a detailed understanding of temperature effects on H. scabra are important in two different ways: 1) to determine the optimal thermal range and delimiting critical temperature levels for best aquaculture practices; 2) to predict the susceptibility of H. scabra to future global warming scenarios. This thesis aims to provide first insights into a mechanistic understanding of how temperature affects H. scabra at different biological organization levels

Light intensity changes and UVB radiation affect peridinin content and antioxidant activity in the Cassiopea andromeda holobiont

IntroductionThe up-side down jellyfish Cassiopea andromeda represents a yet untapped marine species that could be targeted as a new source for functional ingredients, such as natural pigments and antioxidants. Since C. andromeda hosts endosymbiotic dinoflagellates, this jellyfish contains peridinin pigments, which are linked with high antioxidant capacities and many other health-promoting properties. This study investigates the potential to specifically increase the content of peridinin and overall antioxidant activity in C. andromeda, through the targeted application of different photosynthetic active radiation (PAR) intensities and ultraviolet radiation, cultured in fully controlled indoor aquaculture systems.Materials and MethodsIndoor bred C. andromeda specimens were exposed to five different PAR intensities (50, 100, 200, 400 and 800 µmol photons m−2 s−1) and a combined treatment of narrow-band UVB (λ = 285 ± 10 nm) radiation and intermediate (200 µmol photons m−2 s−1) PAR intensity over a period of four weeks. Before the treatment and after two- and four-week treatment intervals, pigment concentrations and antioxidant activity levels were measured using high-performance liquid chromatography (HPLC) and the Trolox Equivalent AntioxidantCapacity (TEAC) assay, respectively. In addition, relative growth rate, umbrella pulsation and photosynthetic efficiency (measured by pulse amplitude modulated fluorometry) of C. andromeda individuals were also monitored throughout the experiment. ResultsChlorophyll a (Chl a) and peridinin (Per) dominated overall pigment content in C. andromeda endosymbionts, chlorophyll c2 and diadinoxanthin were detected in minor amounts. Over the treatment time, Chl a and Per concentrations, measured as µg g−1 jellyfish dry weight and pg microalgae-cell−1, decreased sharply at higher PAR intensities (200 – 800 µmol photons m−2 s−1) compared to the control treatment (100 µmol photons m−2 s−1). After four weeks Chl a and Per concentrations were lowest at the highest PAR intensity (800 µmol photons m−2 s−1) and highest at the lowest PAR intensity (50 µmol photons m−2 s−1). Moreover, the ratio of Chl a and Per showed a relative decrease of Per with increasing PAR intensity. The combined treatment of narrow-band UVB (λ = 285 ± 10 nm) radiation and intermediate (200 µmol photons m−2 s−1) PAR intensity led to significantly elevated Chl a and Per concentrations compared to the 200 µmol photons m−2 s−1 PAR treatment without UVB. Significantly elevated antioxidant activity levels, measured as Trolox Equivalents mmol g−1 jellyfish dry weight, were only detected in UVB exposed C. andromeda, indicating that Chl a and Per did not determine overall antioxidant capacity. The photosynthetic efficiency of C. andromeda endosymbionts was not affected by elevated antioxidant activity. Opposing that, the jellyfish hosts that were exposed to the UVB treatment shrunk drastically, indicating a strong stress response.DiscussionWith this study, we demonstrate for the first time the application potential of PAR intensity manipulations and UVB irradiation, to increase the content of valuable pigments and antioxidants in C. andromeda jellyfish and their endosymbiotic dinoflagellates that live in hospite within the host tissue. Based on these findings, we propose the culture of C. andromeda under fully controlled and light-optimized conditions as new pathway to harness bioproducts and functional ingredients

Biosynthesis of pigments as response to light changes in the up-side down jellyfish Cassiopea andromeda

The published data originate from a laboratory experiment with adult Cassiopea andromeda medusae, which were sourced from an established jellyfish culture bred from polyps (origin: Aquarium Berlin) within the aquaria facilities of the Leibniz Centre for Tropical Marine Research (ZMT), Bremen, Germany. Incubation experiments were conducted in experimental tanks (ETs) in the Marine Experimental Ecology unit (MAREE) of ZMT. The individual ETs function as recirculating aquaculture systems with a water volume of ~120 L, with an upper culture unit and a sump tank equipped with a biofilter system and a protein skimmer below. The temperature and salinity were set at 26°C and 35 SA (Red Sea Salt, Red Sea Fish, Israel), respectively, these conditions were controlled and regulated automatically through submerged sensors. The ETs were each illuminated with an Aquaillumination Hydra FiftyTwo HD (AI Hydra 52 HyperDrive, USA) lamp with seven types of LEDs, emitting the full spectrum (380–680 nm) of photoactive radiation (PAR) with a photon flux density of 100 μmol photons/m²/s. In total, 52 visually healthy (i.e. no injured bells or lost oral arms etc.) Cassiopea andromeda specimens with initial body weights of 111.4 ± 35.7 g and diameters of 10.3 ± 1.3 cm were randomly allocated into 6 ETs. Within these ETs, the animals were individually housed in plastic containers (length 16 cm, width 12 cm, height 12 cm). These containers were fixed just below the water surface, to maintain the same horizontal position and vertical distance under the lamps. This setup allowed for the recognition of individual jellyfish and the precise control of PAR emission on a per-animal basis. Slits on the sides of these plastic containers allowed the exchange of water within the container and the surrounding tank. Over the acclimation and experimental phase, the ETs were cleaned once per week. This included the scratching off of biofilms and the siphoning of feed residues and other particles. During cleaning, approximately one-third of the water volume was exchanged with filtered seawater. In addition, the bacterial film that accumulated at the surface of the water was removed daily with a fine mesh, to prevent the refraction of light through this layer. C. andromeda individuals were target fed daily with 1 mL of dense freshly hatched brine shrimp Artemia nauplii solution using a plastic pipette. One hour after feeding, remaining food residues and any faecal matter were removed from the plastic containers via siphoning with a small plastic pipette. The small plastic boxes were regularly rotated in order to exclude any potential confounding effects associated with different positioning within these tanks. For acclimation purposes, the jellyfish were kept for three weeks in the ETs at a constant PAR intensity of 100 μmol photons/m²/s with 12:12 h light/dark cycle. Light intensities (Li-250A, LI-COR, USA) and spectra (RAMSES ACC-VIS spectroradiometer, TriOS, Germany) were determined at the bottom of the plastic containers. After the acclimation phase, four animals (n = 4) were collected for initial sampling. Subsequently, the PAR intensities in five ETs were changed in steps of no more than 100 μmol photons/m²/s per day, until the desired PAR intensities of 50, 200, 400, and 800 μmol photons/m²/s were reached. For the UVR-treatment, UVB-LEDs (l=285 ± 10 nm) emitting a dose of 1.3 KJ/m²/d were installed above a second ET that reached a final PAR intensity of 200 μmol photons/m²/s. Once the target treatment conditions had been reached, these five different light manipulations remained constant over a four-week period. The sixth ET kept a constant PAR intensity of 100 μmol photons/m²/s throughout the acclimation and experimental phase and served as control treatment. The umbrella pulsation rate, chlorophyll a fluorescence and wet biomass were quantified for each individual C. andromeda medusa initially, after the acclimation phase (day 0) and at the end (day 28) of the different PAR intensity treatments and the exposure to UVB radiation. Umbrella pulsations were counted over 15 s, this number was then extrapolated to determine the number of umbrella pulses per minute and served as proxy for overall organism activity. To exclude the effect of potential handling stress, umbrella pulsations were counted before taking the organisms out of the tanks for further analyses. Chlorophyll a fluorescence was measured using a portable pulse amplitude modulated fluorometer (Diving-PAM, Walz, Effeltrich, Germany). Immediately before the fluorescence measurements, randomly selected C. andromeda specimens (n = 4 per treatment) were collected from the ETs and placed into small glass containers filled with seawater derived from their tanks. In these containers, the animals were kept in darkness for 8 min, to dark-adapt the endosymbiotic dinoflagellates. The subsequent fluorescence measurements included the following steps: 1) a probe with a low-intensity modulated measuring light was placed in close distance to the oral arms and tentacles of each C. andromeda specimen to detect minimal fluorescence (F0) of the dark-adapted endosymbionts. 2) A saturating pulse of light (2700 μmol photons/m²/s) was applied (0.8 s) to obtain the maximum fluorescence (Fm) of the endosymbiotic dinoflagellates. On the basis of F0 and Fm the ratio Fv/Fm was calculated using the formula: Fv = Fm = (Fm − F0) = Fm The ratio Fv/Fm quantifies the maximum quantum efficiency of photosystem II and can serve as a proxy for photosynthetic performance. Right after the fluorescence measurements, the C. andromeda medusa were placed on absorbent tissues for 5 s to remove excess water before determining the wet weight of the jellyfish on a digital scale (Sartorius, Germany). The relative growth rate (RGR) was calculated based on wet biomass weight using the formula: RGR = ln (W2/W1)/DT Where ln is the natural log, W1 is the starting wet weight of one individual jellyfish, W2 is the total jellyfish wet weight after four weeks experimental time and DT is the length of the experiment. For the analyses of pigments and antioxidant activity (AOA), four C. andromeda were sampled after the acclimation phase, after two weeks, and after four weeks (at the end of the experimental period). At each of these time points, whole animals were snap-frozen in liquid N2 and stored at -80°C. Prior to lab-based analyses, the sampled organisms were lyophilized for 72 h at 1 mbar (ALPHA 1-4 LD plus; Christ GmbH, Osterode, Germany). After lyophilization the dry weight of individual organisms were documented before the whole jellyfish were ground to powder for 20 s, using a benchtop homogenizer (FastPrep-24, MP Biomedicals, Germany). For the counting of endosymbiotic algae cells, from each sample, a quantity of ~20 mg lyophilized powder was resuspended in 500 μl of distilled water. For homogenization, the suspension was shaken for 16 h at 60 rpm (Intelli-Mixer RM-2L; ELMI SIA, Riga, Latvia). To prevent cellular clumping, resuspended sample solutions were ultrasonicated twice for 30 s (HD 2070.2; Brandelin electronic GmbH & Co KG, Berlin, Germany) using a Sonotrode (MS 72; 20 KHz, 70 Watt, 285 μm = 100%) with a low amplitude of 20% prior to cell counting. The sample solutions were then pipetted into a Neubauer Hemocytometer (0.1 mm depth), to count the microalgae cells in triplicate under an optical microscope (20x). The total amount of microalgae cells per individual jellyfish, was calculated based on the cell concentration per dry weight of the resuspended jellyfish sub-sample. For pigment analyses, 140 mg of lyophilized sample material was weighed into Eppendorf tubes, after which the pigments therein were extracted in 1 mL of cold 90% acetone for 24 h at 4°C in the dark. After centrifugation (2500g, 4°C, 5 min) and filtration (0.45 μm nylon syringe filters, Nalgene, USA), pigment analyses were performed using reversed-phase high-performance liquid chromatography (HPLC). Pigments (chlorophyll a, peridinin) were separated on a LaChromElite system equipped with a chilled autosampler L-2200 and a DAD detector L-2450 (VWR-Hitachi, Germany) with a LiChropher 100-RP-18 guard cartridge, applying a gradient according to Wright et al. (1991). Peaks were detected at 440 nm, identified, and quantified via co-chromatography with appropriate standards (obtained from DHI Lab Products, Denmark). Pigment concentrations were expressed as μg/g C. andromeda dry weight and as pg/cell of endosymbiotic microalgae. To measure AOA, 200 mg of lyophilized sample was dissolved in 1 mL ethanol (70%) and extracted in a water bath (47°C) for 4 h, vortexing hourly. Prior to this analysis, samples were centrifuged (2500 g, 20°C) for 5 min. The AOA was determined using a modified version of the ABTS+ assay described by Re et al. (1999), also known as the Trolox Equivalent Antioxidant Capacity (TEAC) assay, with Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) serving as a standard. A 2.45 mM ABTS+ stock solution was obtained by oxidizing 7.0 mM of ABTS+ with potassium disulfate (K2S2O8) for 16 h. A working solution with a consistent photometrically measured absorption of 0.7 ± 0.02 at a wavelength of 734 nm (UV/VIS-spectrophotometer, Thermo Scientific Genesys 140/150, Fisher Scientific GmbH, Schwerte, Germany) was obtained via dilution with absolute ethanol. For the AOA analysis, 1 mL of this ABTS+ working solution was added to 10 mL of sample extract, and deradicalization was measured after 6 min. AOA of the samples was expressed as Trolox Equivalents (mmol TE 100 g-1 DW) after adjusting for the appropriate dilution factor. All chemicals were purchased from Sigma (Aldrich/Merck KGaA, Darmstadt, Germany)

Acclimation capability inferred by metabolic performance in two sea cucumber species from different latitudes

The notion that thermal specialists from tropical regions live closer to their temperature limits than temperate eurytherms, seems too generalized. Species specific differences in physiological and biochemical stress reactions are linked to key components of organism fitness, like metabolic capacity, which indicates that acclimation potential across latitudes might be highly diverse rather than simplistic. In this study the exposure of a tropical (Holothuria scabra) and a temperate (Holothuria forskali) sea cucumber species to identical cold- and warmacclimation stress was compared using the key metabolic parameters, respiration rate, enzyme activity (ETS, LDH, IDH), and energy reserve fractions (lipid, carbohydrate and protein). Results show much broader respiratory adjustments, as response to temperature change, in H. scabra (2–30 μgO2*gww−1 *h−1) compared to H. forskali (1.5–6.6 μgO2*gww−1 *h−1). Moreover, the tropical species showed clearly pronounced up and down regulation of metabolic enzymes and shifts in energy reserves, due to thermal acclimation, while the same metabolic indicators remained consistent in the temperate species. In summary, these findings indicate enhanced metabolic plasticity in H. scabra at the cost of elevated energy expenditures, which seems to favor the tropical stenotherm in terms of thermal acclimation capacity. The comparison of such holistic metabolic analyses between conspecifics and congeners, may help to predict the heterogeneous effects of global temperature changes across latitudinal gradients.info:eu-repo/semantics/publishedVersio

Sustainable food protein supply reconciling human and ecosystem health: A Leibniz Position

Many global health risks are related to what and how much we eat. At the same time, the production of food, especially from animal origin, contributes to environmental change at a scale that threatens boundaries of a safe operating space for humanity. Here we outline viable solutions how to reconcile healthy protein consumption and sustainable protein production which requires a solid, interdisciplinary evidence base. We review the role of proteins for human and ecosystem health, including physiological effects of dietary proteins, production potentials from agricultural and aquaculture systems, environmental impacts of protein production, and mitigation potentials of transforming current production systems. Various protein sources from plant and animal origin, including insects and fish, are discussed in the light of their health and environmental implications. Integration of available knowledge is essential to move from a dual problem description (“healthy diets versus environment”) towards approaches that frame the food challenge of reconciling human and ecosystem health in the context of planetary health. This endeavor requires a shifting focus from metrics at the level of macronutrients to whole diets and a better understanding of the full cascade of health effects caused by dietary proteins, including health risks from food-related environmental degradation

World ocean review: Mit den Meeren leben 7. Lebensgarant Ozean – nachhaltig nutzen, wirksam schützen

Im Fokus der siebten Ausgabe des »World Ocean Review« stehen die Auswirkungen des Klimawandels auf die Physik des Meeres und auf seine Lebensgemeinschaften; die Folgen von Fischerei, Schifffahrt, Ressourcenabbau, Energiegewinnung und Meeresverschmutzung sowie die Fragen, wie sich Wirkstoffe aus dem Meer nutzen lassen und wie der Ozean künftig so verwaltet werden kann, dass sowohl sein Schutz als auch die Teilhabe möglichst aller Menschen an seinen Leistungen und Gütern gewährleistet sind