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Author(s): J. Vigliano Relva [sup.1] , C. Van Colen [sup.1] , W. Barhdadi [sup.2] , A. J. Daly [sup.2] , M. De Troch [sup.1] Author Affiliations: (1) https://ror.org/00cv9y106, grid.5342.0, 0000 [...], Copepods are aquatic invertebrates with a key role at the basis of marine food webs due to their high biomass as well as their elevated fatty acid (FA) content. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are two FA abundant in copepods which have a well demonstrated role in growth and reproduction in marine organisms. While the majority of research has focused on planktonic copepod species, less is known for benthic species despite their high richness, abundance and their role as the main food source for many fish larvae. Temperature is a key driver of organism's fitness as well as ecosystem functioning and sea surface temperature is expected to rise under all CO.sub.2 emission scenarios. Thus, understanding how copepods will respond to such changes is crucial given their role in marine food webs. In this study we expose laboratory reared Tachidius discipes, an intertidal benthic copepod to a temperature gradient (12, 15, 18, 21 and 24 °C) including current seasonal variability as well as future scenarios. Survival, FA, growth rates and nauplii production were measured for each temperature. We found decreased survival, increased growth rates and detrimental effects for nauplii production with temperature increase. While relative EPA and DHA decreased with temperature this was not found on absolute levels of these FA. Changes in benthic copepods' biomass as well as their FA composition in response to temperature changes could amplify to higher trophic levels with consequences for food web functioning.

From a conservation p0oint of view, it is essential to know how fast an ecosystem can recover after physical disturbance. Meiofauna and especially harpacticoid copepods are abundant in seagrass beds and are therefore useful to study ecosystem recovery after disturbance. In the western Caribbean coast, a fragmented Thalassia testudinum seagrass bed was selected to conduct a colonization field experiment by means of plastic seagrass mimics. Meiofauna colonization, with special emphasis on harpacticoid copepods, was followed in relation to: (1) colonization time (2, 4, 6, 10, 14 and 21 days); (2) distance to source of colonizers (close and far series) and (3) leaf surface area to colonize (small, medium, large). Colonization was recorded after 2 days with average meiofauna densities of 480 ind/100 [cm.sup.2] (close) and 1350 ind/100 [cm.sup.2] (far) of leaf surface area, while on average 400 ind/100 [cm.sup.2] were collected from the natural seagrass plants. In this early phase, the meiofauna diversity was high, with on average 8 taxa. A longer period of colonization (21 days) showed an increased meiofaunal density and diversity (average density: 3220 ind/100 [cm.sup.2], 13 taxa). Increasing meiofauna colonization with time is probably related to the development of a biofilm making the leaf more attractive for meiofauna. The effect of distance was not so pronounced as that of time. Total absolute densities were highest in the far series (5 m away from natural seagrass patch), mainly because of nematode densities. Meiofauna diversity was lower in the far series than in the close series (at the border of the natural seagrass patch). A larger individual leaf surface area did not affect the overall meiofauna densities but had a significant positive effect on copepod densities. Larger surface areas promoted the presence of epiphytic copepod families such as Tegastidae and Dactylopusiidae. Overall, we found a rapid recovery of meiofauna in fragmented seagrass beds with primary colonizers (both nematodes and benthic opportunistic copepods) originating from the sediment and later colonizers as epiphytic copepods and their nauplii from the local seagrass regeneration pool., Introduction Changes in land use have led to a steady loss of habitat and to an increasing isolation of habitat remnants throughout the world. Habitat destruction and fragmentation are major [...]

Several harpacticoid copepod species are adapted to an epiphytic lifestyle. Previous studies on tropical seagrass meiofauna mainly focussed on the epiphytic communities and neglected the benthic component. The present study aims to document the benthic harpacticoid copepod communities sampled from different sediment depth horizons adjacent to five seagrass species in the intertidal and subtidal zone of a tropical seagrass bed (Gazi Bay, Kenya). Two benthic copepod communities could be identified mainly based on the tidal position of the samples: a first community was collected near the intertidal seagrasses Halophila ovalis and Halodule wrightii; a second community occurred near the subtidal seagrasses Thalassia hemprichii, Syringodium isoetifolium and Halophila stipulacea. The first community was mainly determined by sediment characteristics (e.g. skewness), while the second community was split off based on organic matter content (% TOM), nutrient and pigment values. A subtle combination of horizontal and vertical niche segregation was reported for the dominant copepod families. Species of the families Thalestridae, Laophontidae and Diosaccidae were structured by tidal position and showed a strong preference for the subtidal zone. The opposite strategy, i.e. a clear preference for the intertidal zone, was found for copepods belonging to the families Paramesochridae and Canuellidae. In addition, Apodopsyllus africanus (Paramesochridae) was well-adapted to stress and was concentrated in the deeper sediment layers near the subtidal seagrasses. On the other hand, Canuellidae, as filter feeders, were concentrated in the upper centimetres of the sediment. The families Ectinosomatidae and Cletodidae did not show any vertical or horizontal segregation. On the species level, however, clear horizontal niche segregation was detected for the family Cletodidae. In addition to the reported ecological results, the study material was used to evaluate different niche definitions. We found tidal position to be the most important factor forcing harpacticoids to specialise. Sediment depth horizon was less powerful in dividing the families into different guilds (from specialists to generalists) based on standardised niche breadth. The present study documents the subtle habitat partitioning of co-existing species in a limited area and its role in sustaining high biodiversity in the community.

Temperature up-shift and UV-A radiation effects on growth, lipid damage, fatty acid (FA) composition and expression of desaturase genes desA and desB were investigated in the cyanobacteria Microcystis aeruginosa. Although UV-A damaging effect has been well documented, reports on the interactive effects of UV radiation exposure and warming on cyanobacteria are scarce. Temperature and UV-A doses were selected based on the physiological responses previously obtained by studies with the same M. aeruginosa strain used in this study. Cells pre-grown at 26 °C were incubated at the same temperature or 29 °C and exposed to UV-A + PAR and only PAR for 9 days. Growth rate was significantly affected by UV-A radiation independently of the temperature throughout the experiment. High temperature produced lipid damage significantly higher throughout the experiment, decreasing at day 9 as compared to 26 °C. In addition, the cells grown at 29 °C under UV-A displayed a decrease in polyunsaturated FA (PUFA) levels, with ω3 PUFA being mostly affected at the end of exposure. Previously, we reported that UV-A-induced lipid damage affects differentially ω3 and ω6 PUFAs. We report that UV-A radiation leads to an upregulation of desA, possibly due to lipid damage. In addition, the temperature up-shift upregulates desA and desB regardless of the radiation. The lack of lipid damage for UV-A on ω3 could explain the lack of transcription induction of desB. The significant ω6 decrease at 26 °C in cells exposed to UV-A could be due to the lack of upregulation of desA., (© 2024. The Author(s), under exclusive licence to the European Photochemistry Association, European Society for Photobiology.)

Environmental characteristics influence the fatty acids (FAs) of aquatic organisms. Environmental factors and anthropic actions such as water pollution can impact FA composition. This directly affects the trophic network, especially when low-quality FA is provided to other trophic levels. The omnivore Penaeoidea shrimp is rich in proteins and polyunsaturated fatty acids (PUFA), representing an important node in the trophic web. We compared the FA composition of the commercially exploited seabob shrimp Xiphopenaeus spp. in two distinct coastal sites, Cananéia and Ubatuba, on the southeast Brazilian coast. Cananéia has a low human population density and is a preserved area with nearby mangroves, while Ubatuba is highly urbanised and influenced by tourism (increasing the domestic sewage), with diverse microhabitats but without mangrove influence. We found a total of 29 different FAs in seabob shrimp samples. Saturated FAs and PUFAS were the most representatives. For sex or age (juvenile and adult), deviations were found in the monosaturated FA, ω6, and ω3/ω6. However, FA composition was significantly different between sites, with Ubatuba presenting a lower abundance of FAs than Cananéia. The fatty acid composition of Xiphopenaeus spp. was influenced by environmental quality factors such as dissolved oxygen, chlorophyll, organic matter, and size gradient. The presence of high amounts of organic matter (especially sewage) during decomposition can decrease dissolved oxygen levels, reducing the quality of the first producers and limiting the availability of FAs for other trophic levels. The study suggests that water pollution and mangrove forests can impact the FAs of Xiphopenaeus spp., potentially reducing their nutritional value and causing an imbalance in the transference of FAs., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The combined effects of increased temperature and solar ultraviolet radiation (UVR, 280-400 nm) on M. aeruginosa cultures was analyzed in terms of cell abundance, reactive oxygen and nitrogen species (ROS/RNS), antioxidant activity of catalase (CAT), superoxide dismutase (SOD), glutathione S transferase (GST), fatty acids (FA) content and lipid damage. After 12 days exposure to high temperature (29 °C), cells were exposed to solar UVR (4 h). Ultraviolet-B radiation (UVBR, 280-315 nm) resulted into low cell abundance, high ROS/RNS and a significant increase in SOD activity with no changes in GST and a decreased CAT activity at control temperature (26 °C). A significant increase in the analyzed enzymatic antioxidants was observed at 29 °C, as a response to avoid ultraviolet-A radiation (UVAR, 315-400 nm) damage. The relative abundance of ω6 FAs was not affected by UVAR while ω3 FA were highly sensitive at 29 °C but unsaturated fatty acids (UFA) peroxidation did not occur. The differential response in FA to high temperature and UVAR results in differences in lipid damage and antioxidants. It was evident that selected UFAs (mostly ω6) play an important role in high temperature adaptation in addition to enzymatic antioxidant increased activity shifting the temperature growth from 26 to 29 °C. Thus, cell death and UFA damage were avoided at high temperature and low solar irradiance thanks to an increased enzymatic antioxidant activity.

The use of stable isotope (SI) labelling and tracing of live diets is currently considered one of the most comprehensive tools to detect their uptake and assimilation by aquatic organisms. These techniques are indeed widely used in nutritional studies to follow the fate of specific microbial dietary components, unraveling trophic interactions. Nevertheless, to the current date our understanding of aquatic trophic relationships has yet to include a whole domain of life, the Archaea. The aim of the present research was, therefore, to describe a halophilic Archaea (haloarchaea) labelling procedure, using the SI 13 C and 15 N, to enable the application of SI tracing in future studies of haloarchaea consumption by aquatic metazoans. To this end, three 13 C enriched carbon sources and two 15 N enriched nitrogen sources were tested as potential labels to enrich cells of three haloarchaea strains when supplemented to the culture medium. Our overall results indicate 13 C-glycerol as the most effective carbon source to achieve an efficient 13 C enrichment in haloarchaea cells, with Δδ 13 C values above 5000‰ in all tested haloarchaea strains. As for 15 N enriched nitrogen sources, both ( 15 NH 4 ) 2 SO 4 and 15 NH 4 Cl seem to be readily assimilated, also resulting in efficient 15 N enrichment in haloarchaea cells, with Δδ 15 N values higher than 20,000‰. We believe that the proposed methodology will allow for the use of SI labelled haloarchaea biomass in feeding tests, potentially providing unambiguous confirmation of the assimilation of haloarchaea biomass by aquatic metazoans.

Mixture effects of chemicals and their potential synergistic interactions are of great concern to the public and regulatory authorities worldwide. Intensive agricultural activities are leading to discharges of chemical mixtures to nearby estuarine and marine waters with possible adverse effects on the aquatic communities and for the trophic food web interlinking these communities. Further information about the impacts of these stressors on aquatic organisms is needed. This study addresses ecotoxicological and biochemical effects of single and mixtures of the metal copper and the herbicide Primextra® Gold TZ on the marine diatom Thalassiosira weissflogii and on the estuarine calanoid copepod Acartia tonsa by determining growth rate and survival, respectively, and changes on fatty acid(FA) profiles in both species. Mixture effects on diatom species revealed that copper and Primextra® acted most likely additively with respect to the concentration addition (CA) and independent action (IA) models with model deviation ratios (MDR), 0.752 and 1.063, respectively. For the copepod species, copper and Primextra® were most likely non-interactive with respect to the CA model (MDR = 1.521) but acted most likely synergistically with respect to the IA model (MDR = 2.026). A significant decline in the absolute FA concentration was observed for copepod species after mixture exposure including a considerable decrease of essential FAs that cannot be synthesized de novo by these grazers. We concluded that the mixture effects are more hazardous for primary consumer than for primary producer species in terms of both abundance and biomass quality, suggesting a potential for harmful effects for higher trophic levels and thus a decrease in energy flow through the ecosystem.

Background: Patients with gastrointestinal mucosa-associated lymphoid tissue (MALT) lymphoma require lifelong endoscopic follow-up. This study aimed to establish and evaluate confocal laser endomicroscopy (CLE) criteria for gastrointestinal MALT lymphoma., Methods: This prospective trial was conducted after IRB approval at the Medical University of Vienna. Twenty-four consecutive patients (14 males and 10 females, median age 65 years) referred for staging or follow-up of (former) gastrointestinal MALT lymphoma underwent endosonography (EUS) and CLE including white light endoscopy (WLE) and conventional biopsy sampling of the upper gastrointestinal tract. CLE criteria of the disease were based on the first five patients with histologically proven MALT lymphoma. All CLE datasets were reviewed separately by two CLE experts. The diagnostic modalities were compared using conventional histology as the gold standard., Results: Sixty-two percentages had a positive diagnosis of MALT lymphoma based on histology. The sensitivity was 80 % for EUS (0.51-0.95), 100 % for WLE (0.75-1) and 93 % for CLE (0.66-1); the specificity was 67 % for EUS (0.31-0.91), 23 % for WLE (0.04-0.60) and 100 % for CLE (0.63-1). The agreement with histology was moderate for EUS (kappa 0.47, p = 0.02), fair for WLE (kappa 0.26, p = 0.06) and almost perfect for CLE (kappa 0.91, p < 0.01). Expert evaluation identified all but one case of MALT lymphoma with excellent interobserver agreement (kappa 0.89, p < 0.01). In the case missed by CLE, MALT lymphoma involvement was restricted to deep tissue structures., Conclusions: Despite minor technical limitations, CLE is a promising alternative to conventional biopsy sampling in patients with gastrointestinal MALT lymphoma. CLINICALTRIALS., Gov Number: NCT01583699.