Helena Abreu

Distribution and population dynamics of the introduced seaweed Grateloupia turuturu (Halymeniaceae, Rhodophyta) along the Portuguese coast

Araújo R., Violante J., Pereira R., Abreu H., Arenas F. and Sousa-Pinto I. 2011. Distribution and population dynamics of the introduced seaweed Grateloupia turuturu (Halymeniaceae, Rhodophyta) along the Portuguese coast. Phycologia 50: 392–402. DOI: 10.2216/10-65.1 Despite the increasing number of coastal areas invaded over the last years by the introduced seaweed Grateloupia turuturu, studies on this species are scarce worldwide, and its invasive capability and future impacts remain unexplored. In the present study, we describe the geographical distribution of the species after a few years of colonization of the Portuguese continental coastline. Additionally, we examine the structure and dynamics of one of the first population of Grateloupia in our shores. Seasonal dynamics of standing biomass, density, size structure and inequality (size variability), together with the presence of fertile fronds were investigated during one year. Grateloupia was recorded in midintertidal pools at 11 of the 36 localities sampled, two of which presenting an elevated abundance of fronds. Fronds were present during the entire year, but their size (length and biomass), density and size inequality varied seasonally reaching highest values at the beginning of the summer. The annual cycle of the population studied included a slow-growth phase in winter, a fast-growth phase during spring-early summer when some density-dependent regulation appeared to occur, as well as a dieback phase at the end of summer. In terms of fertility, abundance of fronds bearing reproductive structures were seasonally variable although carposporophytic and tetrasporophytic fronds were recorded throughout the year. The results of this work highlight some of the biological characteristics of Grateloupia turuturu that may determine its invasive nature and its possible impact on native ecosystems.

Effects of dietary Gracilaria sp. and Alaria sp. supplementation on growth performance, metabolic rates and health in meagre (Argyrosomus regius) subjected to pathogen infection

Effects of dietary seaweed supplementation on basal physiology and health biomarkers were assessed in meagre (Argyrosomus regius) subjected to bacterial infection, using Photobacterium damselae subsp. Piscicida (Phdp) as the etiologic agent. Three test diets were prepared by supplementing a basal control formulation (44xa0% protein, 16xa0% lipid, 22xa0kJxa0g−1 energy) with 0xa0% seaweed (control), 5xa0% Gracilaria sp. or 5xa0% Alaria sp. During the growth trial, 180 fish (39.70xa0±xa00.33xa0g) were daily fed for 69xa0days with the experimental diets. After the growth trial, 60 fish from each dietary treatment were divided into two groups, infected and non-infected. The infected group was injected intraperitoneally with a saline solution (HBSS) with 2.91 x 103xa0CFU Phdp g−1 fish, whereas the non-infected group was injected with HBSS without Phdp. Dietary seaweed supplementation did not affect fish growth performance. Standard and routine metabolic rates, and aerobic metabolic scope did not vary significantly among dietary treatments. Conversely, maximum metabolic rate was significantly higher in fish fed Alaria sp. diet when compared to control group. Non-infected fish had higher hematocrit levels than the infected group, regardless of diet. Lactate levels were significantly higher in fish fed Alaria sp. diet when compared to control, with no interaction between diet and infection. Lipid peroxidation was significantly higher in fish fed control diet than supplemented diets. Infected groups had lower antioxidant enzymes activities when compared to non-infected. An interaction between infection and diet was found for glutathione peroxidase and reduced glutathione activities. The current study suggests that dietary seaweed supplementation modulates metabolic rates and biomarker responses in meagre, which may confer advantages in coping with biotic stressors.

Dietary supplementation of heat-treated Gracilaria and Ulva seaweeds enhanced acute hypoxia tolerance in gilthead seabream (Sparus aurata)

ABSTRACT Intensive aquaculture practices involve rearing fish at high densities. In these conditions, fish may be exposed to suboptimal dissolved O2 levels with an increased formation of reactive O2 species (ROS) in tissues. Seaweeds (SW) contain biologically active substances with efficient antioxidant capacities. This study evaluated the effects of dietary supplementation of heat-treated SW (5% Gracilaria vermiculophylla or 5% Ulva lactuca) on stress bioindicators in sea bream subjected to a hypoxic challenge. 168 fish (104.5 g average weight) were distributed in 24 tanks, in which eight tanks were fed one of three experimental diets for 34 days: (i) a control diet without SW supplementation, (ii) a control diet supplemented with Ulva, or (iii) a control diet with Gracilaria. Thereafter, fish from 12 tanks (n=4 tanks/dietary treatment) were subjected to 24 h hypoxia (1.3u2005mgu2005O2 l−1) and subsequent recovery normoxia (8.6u2005mgu2005O2 l−1). Hypoxic fish showed an increase in hematocrit values regardless of dietary treatment. Dietary modulation of the O2-carrying capacity was conspicuous during recovery, as fish fed SW supplemented diets displayed significantly higher haemoglobin concentration than fish fed the control diet. After the challenge, survival rates in both groups of fish fed SW were higher, which was consistent with a decrease in hepatic lipid peroxidation in these groups. Furthermore, the hepatic antioxidant enzyme activities were modulated differently by changes in environmental O2 condition, particularly in sea bream fed the Gracilaria diet. After being subjected to hypoxia, the gene expression of antioxidant enzymes and molecular chaperones in liver and heart were down regulated in sea bream fed SW diets. This study suggests that the antioxidant properties of heat-treated SW may have a protective role against oxidative stress. The nature of these compounds and possible mechanisms implied are currently being investigated. Summary: The physiological response and survival rate of gilthead sea bream to hypoxia was highly modulated by dietary supplementation of heat-treated seaweed.

Impact of cultivation of Mastocarpus stellatus in IMTA on the seaweeds chemistry and hybrid carrageenan properties

The biomass yield potential of Mastocarpus stellatus, a commercially attractive carrageenophyte for foods and pharmaceutics, was investigated by cultivating the seaweeds in the nutrient-rich outflow of a commercial fish farm. Results from two consecutive 4 weeks experiments indicate that the cultivation of this seaweed produces a mean biomass of 21 to 40.6 gDW m(-2) day(-1) depending on the time of the experiment. DRIFT and CP-MAS NMR analyses of seaweeds indicate that cultivation during May affected quantitatively the seaweeds chemistry, and thus the chemical and gelling properties of native extracts of kappa/iota-hybrid carrageenan (KI). Overall, algal growth leads to the production of more sulphated KI, the percentage increase varying between 27% and 44% for the two experiments. However, alkali treatment of seaweeds before extraction reduces the variations in gelling properties of KI induced by the algal growth. This study demonstrates the capacity of growing M. stellatus in an integrated multi-trophic aquaculture system for the sustainable production of high value polysaccharides.

Environmental Impacts of Experimental Production of Lactic Acid for Bioplastics from Ulva Spp.

An exploratory Life Cycle Assessment (LCA) was carried out to provide insight into the environmental impacts of using the green seaweed Ulva spp. as a feedstock, for production of bioplastic. The study focused on the production of lactic acid as a precursor of polylactic acid. The study was on the production process: (1) The cultivation of Ulva spp., in an Integrated Multitrophic Aquaculture system; (2) the processing of the biomass for solubilization of sugars; (3) the fermentation of the sugars to lactic acid; (4) the isolation of lactic acid from fermentation broth. The study identified environmental hotspots and compared an experimental seaweed production chain with conventional feedstocks. The main hotspot is derived from electricity consumption during seaweed cultivation. The impact of electricity consumption can be lowered by reducing energy use and sourcing renewable energy, and by improving the material efficiency in the product chain. To improve understanding of the process of production’s environmental impacts, future studies should broaden the system boundaries and scope of sustainability issues included in the environmental assessment.

Searching for antigenotoxic properties of marine macroalgae dietary supplementation against endogenous and exogenous challenges

ABSTRACT The functional characterization of marine macroalgae toward their potential to strength genome protection is still scarce. Hence, the aim of this study was to assess the antigenotoxic potential of Ulva rigida, Fucus vesiculosus, and Gracilaria species in Drosophila melanogaster following dietary exposure and adopting the somatic mutation and recombination test (SMART). All macroalgae displayed a genoprotection activity, namely against an exogenous challenge (streptonigrin). The action against subtler endogenous pressures was also noted indicating that supplementation level is a critical factor. Gracilaria species provided ambivalent indications, since 10% of G. vermiculophylla inhibited the egg laying and/or larvae development, while 10% of G. gracilis promoted spontaneous genotoxicity. The effects of U. rigida were modulated (in intensity) by the growing conditions, demonstrating higher genoprotection against streptonigrin-induced damage when grown in an aquaculture-controlled system, while the effectiveness against spontaneous genotoxicity was more apparent in specimens grown under wild conditions. In contrast, F. vesiculosus did not produce significant differences in its potential under varying growing conditions. Overall, these findings shed some light on the macroalgae ability toward genome protection, contributing to the development of algaculture industry, and reinforcing the concept of functional food and its benefits.