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Chemical predator signals induce metabolic suppression in rock goby (Gobius paganellus)

Publication . Paul, Nina; Novais, Sara C.; Lemos, Marco F. L.; Kunzmann, Andreas

In nature, a multitude of both abiotic and biotic stressors influence organisms with regard to their overall fitness. Stress responses that finally impair normal biological functions may ultimately result in consequences for whole populations. This study focused on the metabolic response of the intertidal rock pool fish Gobius paganellus towards simulated predation risk. Individuals were exposed to a mixture of skin extracts from conspecifics and chemical alarm cues from a top predator, Octopus vulgaris. Oxygen consumption rates of single fish were measured to establish standard (SMR) and routine metabolic rates (RMR) of G. paganellus, and to address the direct response towards simulated predation risk, compared to handling and light stress. The SMR of G. paganellus (0.0301 ± 0.0081 mg O2 h-1 g-1 WW) was significantly lower than the RMR (0.0409 ± 0.0078 mg O2 h-1 g-1 WW). In contrast to increased respiration due to handling and light stress, the exposure to chemical predation cues induced a significant reduction in oxygen consumption rates (0.0297 ± 0.0077 mg O2 h-1 g-1 WW). This metabolic suppression was interpreted as a result of the stereotypic freezing behaviour as antipredator response of gobiid fish. Results underline the importance of biotic interactions in environmental stress assessments and predation as a biotic factor that will provide more realistic scenarios when addressing stress impacts in tidal rock pool organisms.

2018Journal article

Open access

Effects on biomarkers in stress ecology studies. Well, so what? What now?

Publication . Lemos, Marco F.L.; Duarte, Bernardo; Fonseca, Vanessa; Novais, Sara C.

1. Biomarkers in Stress Ecology - From the Gene to Population Effects assessed at higher levels of biological organization (populations and communities) are the consequence of the sum of effects on individuals, which usually result from impacts at cellular and molecular levels. Given this rationale, these lower levels of biological organization are more responsive at an early stage, making them potential resources that can be used as early warning endpoints to address environmental stress. In this way, the information concerning effects at the molecular level of biological organization (e.g., transcripts, proteins, or metabolites) allows for an early assessment of future ecosystem problems, which may eventually enable a timely intervention before the impacts become visible and irreversible. However, despite providing an early warning and a better understanding of the toxicity mechanisms, enabling the protection of biological integrity, the most significant setback is that these endpoints may fail to foresee later impacts on the environment due to the ecosystem resilience or a weak link to the effects in the following level of biological organization, making these tools simply too conservative for stakeholders’ interests. Hence, an approach targeting lower levels of biological organization will greatly benefit from addressing potential effects at higher levels. This can be achieved by establishing a link in biological organization, where the effects assessed at the lower end of biological organization are linked with the high probability of causing an effect at the other end, inducing changes in populations and communities, and eventually altering ecosystems in the future.

2022Journal article

Open access

Tailoring shrimp aquafeed to tackle Acute Hepatopancreatic Necrosis Disease by inclusion of industry-friendly seaweed extracts

Publication . Félix, Rafael; Félix, Carina; Januário, Adriana P.; Carmona, Ana M.; Baptista, Teresa; Gonçalves, Rui A.; Sendão, João; Novais, Sara C.; Lemos, Marco F.L.

Shrimp farming has been severely affected by Vibrio infections in southeastern Asia, with severe economic impacts. Invasive seaweeds are an increasing threat that can be strategically valorized by biotechnology, promoting economic development while contributing to ecologic remediation. Asparagopsis armata and Sargassum muticum are two such species that have been frequently reported as excellent bioactive compounds producers, namely anti-bacterial and antioxidant. Thus, A. armata and S. muticum were extracted in an industry-focused approach, using low amounts of ethanol and short extraction times at room temperature. Yield, in vitro antioxidant capacity by the 2,2-diphenyl−1-picrylhydrazyl radical scavenging assay, and in vitro antibacterial activity against Vibrio parahaemolyticus (microdilution) were optimized using Response Surface Methodology (RSM). Optimal extracts (one from each seaweed species) were incorporated in feed, and an in vivo trial using the whiteleg shrimp Penaeus vannamei was performed in industrial facilities using the supplemented feed (1.5, 3.5 and 7.5 g extract per kg feed). Feed quality (along an 8-week period under regular storage conditions) and shrimp performance (40-day trial) were studied, as well as post-challenge (infection by virulent Vibrio parahaemolyticus) mortality rate and hepatopancreas condition. The results from the RSM showed that lower extraction times and ethanol volumes maximized extracts' bioactive properties (A. armata – 20 min, 10 mL solvent per gram seaweed; S. muticum – 100 min, 10 mL.g−1). The seaweed extracts did not impact shrimp performance (no statistically significant differences in weight gain, feed conversion rate or survival). Asparagopsis armata selected extract at 7.5 g per kg feed was able to decrease feed contamination by fungi along time and reduce shrimp mortality by up to 50% upon challenge with V. parahaemolyticus. Despite lacking statistical significance, a difference in hepatopancreas condition after challenge could be identified in shrimp fed the supplemented feed.

2020Journal article

Restricted access

Marine invasive species for high-value products' exploration: Unveiling the antimicrobial potential of Asparagopsis armata against human pathogens

Publication . Pinteus, Susete; Lemos, Marco F.L.; Simões, Marco; Alves, Celso; Silva, Joana; Gaspar, Helena; Martins, Alice; Rodrigues, Américo; Pedrosa, Rui

Infectious diseases remain one of the leading global causes of death, mainly due to the increasing number of multi-resistant microorganisms. Therefore, novel antimicrobials are continuously needed. Marine organisms have already proven to be a rich source of bioactive compounds which can be used for the development of novel pharmacological drugs. Within these, seaweeds are an important resource still underexplored. Asparagopsis armata is a marine invasive seaweed that has spread along several coastlines of the world, inducing negative pressures in marine ecosystems. Therefore, it is crucial to develop strategies to counteract their impacts. In this work, A. armata was extracted with methanol and dichloromethane (1:1) and fractionated by column chromatography with different polarity solvents, providing 8 fractions (F1-F8). All the fractions were evaluated for their antimicrobial potential against important human pathogens, namely Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis, and Candida albicans. Additionally, their capacity to inhibit biofilms formation and the effects on cytoplasmatic membrane and DNA integrity were also assessed. The most active fractions were further purified and submitted to GC–MS analysis. The results showed that A. armata produces compounds with a high inhibitory activity against S. aureus, P. aeruginosa, and C. albicans growth, possibly mediated by cytoplasmatic membrane disruption and DNA damage. GC–MS analysis suggested that the most active fractions were mainly composed of bromoditerpenes and fatty acids. The attained results point to the relevance of the invasive A. armata as a source of antimicrobial substances with broad-spectrum activity. The use of invasive species to obtain natural bioactive compounds presents a two-folded opportunity - high availability of the biological material for the extraction of bioactive compounds and, through specimen collection, the mitigation of the negative effects caused by invasive species, contributing to ecosystem integrity and sustainability.

2020Journal article

Restricted access

Spotting intruders: Species distribution models for managing invasive intertidal macroalgae

Publication . Blanco, A.; Larrinaga, A.R.; Neto, J.M.; Troncoso, J.; Méndez, G.; Domínguez-Lapido, P.; Ovejero, A.; Pereira, L.; Mouga, T.; Gaspar, R.; Martínez, B.; Lemos, M.F.L.; Olabarria, C.

Invasive macroalgae represent one of the major threats to marine biodiversity, ecosystem functioning and structure, as well as being important drivers of ecosystem services depletion. Many such species have become well established along the west coast of the Iberian Peninsula. However, the lack of information about the distribution of the invaders and the factors determining their occurrence make bioinvasions a difficult issue to manage. Such information is key to enabling the design and implementation of effective management plans. The present study aimed to map the current probability of presence of six invasive macroalgae: Grateloupia turuturu, Asparagopsis armata, Colpomenia peregrina, Sargassum muticum, Undaria pinnatifida, and Codium fragile ssp. fragile. For this purpose, an extensive field survey was carried out along the coast of the north-western Iberian Peninsula. Species distribution models (SDMs) were then used to map the presence probability of these invasive species throughout the study region on the basis of environmental and anthropogenic predictor variables. The southern Galician rias were identified as the main hotspots of macroalgal invasion, with a high probability of occurrence for most of the species considered. Conversely, the probability of presence on the Portuguese coast was generally low. Physico-chemical variables were the most important factors for predicting the distribution of invasive macroalgae contributing between 57.27 and 85.24% to the ensemble models. However, anthropogenic factors (including size of vessels, number of shipping lines, distance from ports, population density, etc.) considerably improved the estimates of the probability of occurrence for most of the target species. This study is one of the few to include anthropogenic factors in SDMs for invasive macroalgae. The findings suggest that management actions aimed at controlling these species should strengthen control and surveillance at ports, particularly in southern Galician rias. Early detection should be of main concern for risk assessment plans on the Portuguese coast.

2021Journal article

Restricted access