Endemic Seaweed Research Articles

Ascertaining the spatiotemporal variations in seaweed assemblages associated with the endemic seaweed Ulva ovata along selected locations of the Gulf of Khambhat, India

Ascertaining the spatiotemporal variations in seaweed assemblages associated with the endemic seaweed Ulva ovata along selected locations of the Gulf of Khambhat, India

Antidiarrheal activity of a novel sulfated polysaccharide from the red seaweed Gracilaria cervicornis

Ethnopharmacological relevanceThe use of marine seaweeds as a source of natural compounds with medicinal purposes is increasing in Western countries in the last decades, becoming an important alternative in the traditional medicine of many developing countries, where diarrhea still remains a severe public health problem, with high rates of mortality and morbidity. Sulfated polysaccharides (PLS) extracted from red seaweeds can exhibit therapeutic effects for the treatment of gastrointestinal disorders. Thus, the pharmacological properties of the PLS from Gracilaria cervicornis, an endemic seaweed found in the Brazilian northeast coast, was evaluated as an alternative natural medication for diarrhea. Aim of the studyThis study aimed to evaluate the antidiarrheal activity of sulfated polysaccharides (PLS) extracted from the red seaweed G. cervicornis in Swiss mice pre-treated with castor oil or cholera toxin. Materials and methodsThe seaweed Gracilaria cervicornis was collected at Flecheiras beach (city of Trairí, State of Ceará, Brazil) and the PLS was obtained through enzymatic extraction and administered in mice (25–30 g) before diarrhea induction with castor oil or cholera toxin. For the evaluation of the total number of fecal output and diarrheal feces, the animals were placed in cages lined with adsorbent material. The evaluation of intestinal fluid accumulation (enteropooling) on castor oil-induced diarrhea in mice occurred by dissecting the small intestine and measuring its volume. The determination of Na+/K+-ATPase activity was measured in the small intestine supernatants by colorimetry, using commercial biochemistry kits. The gastrointestinal motility was evaluated utilizing an activated charcoal as a food tracer. The intestinal fluid secretion and chloride ion concentration were evaluated in intestinal closed loops in mice with cholera toxin-induced secretory diarrhea. The binding ability of PLS with GM1 and/or cholera toxin was evaluated by an Enzyme-Linked Immunosorbent Assay (ELISA). ResultsThe G. cervicornis PLS showed antidiarrheal effects in both acute and secretory diarrhea, reducing the total number of fecal output, diarrheic stools, intestinal fluid accumulation, and increasing small intestine Na+/K+-ATPase activity on castor oil-induced diarrhea. However, the PLS did not affect gastrointestinal motility, indicating that this compound has a different action mechanism than loperamide. In secretory diarrhea, the PLS decreased intestinal fluid secretion and small intestine chloride excretion, binding with GM1 and/or cholera toxin and blocking their attachment to the enterocyte cell surface. ConclusionsIn conclusion, PLS has a significant antidiarrheal effect in acute and secretory diarrhea. Further investigation is needed towards its use as a natural medicine to treat diarrhea.

Halimeda jolyana (Bryopsidales, Chlorophyta) presents higher vulnerability to metal pollution at its lower temperature limits of distribution.

Seaweeds living at their temperature limits of distribution are naturally exposed to physiological stressors, facing additional stress when exposed to coastal pollution. The physiological responses of seaweeds to environmental conditions combining natural and anthropogenic stressors provide important information on their vulnerability. We assessed the physiological effects and ultrastructural alterations of trace metals enrichment at concentrations observed in polluted regions within the temperature ranges of distribution of the endemic seaweed Halimeda jolyana, an important component of tropical southwestern Atlantic reefs. Biomass yield and photosynthetic performance declined substantially in samples exposed to metal, although photosynthesis recovered partially at the highest temperature when metal enrichment was ceased. Metal enrichment caused substantial ultrastructural alterations to chloroplasts regardless of temperatures. The lack of photosynthetic recovery at the lower temperatures indicates a higher vulnerability of the species at its temperature limits of distribution in the southwestern Atlantic.

An experimental evaluation of the direct and indirect effects of endemic seaweeds, barnacles, and invertebrate predators on the abundance of the introduced rocky intertidal barnacle Balanus glandula

AbstractThe barnacle, Balanus glandula has recently invaded along the Pacific coast of eastern Hokkaido, Japan. To evaluate the direct and indirect effects of endemic seaweeds, barnacles, and invertebrate predators on the abundance of B. glandula on the rocky intertidal coast of eastern Hokkaido, we conducted a field experiment from June 2011 to October 2012 in which we manipulated the presence or absence of these factors. Seaweeds showed no significant effect on the abundance of B. glandula. The endemic barnacle Chthamalus dalli and the invertebrate predator Nucella lima reduced the abundance of B. glandula. However, the simultaneous influence of N. lima and C. dalli was compensative rather than additive, probably due to keystone predation. These findings suggest that competition by the endemic barnacle C. dalli and predation by the invertebrate predator N. lima decreased the abundance of B. glandula, but that N. lima predation on C. dalli weakened the negative influence of C. dalli on B. glandula. The implications of these findings are twofold: the endemic competitor and invertebrate predator may have played important roles in decreasing the abundance of B. glandula in natural habitats, and conservation of endemic invertebrate predators may be crucial to impede the establishment and survival of introduced barnacles in rocky intertidal habitats.

Arthropod diversity associated with the non-indigenous macroalgae Asparagopsis armata Harvey, along the Atlantic coast of the Iberian Peninsula

Arthropod diversity associated with the non-indigenous macroalgae Asparagopsis armata Harvey, along the Atlantic coast of the Iberian Peninsula

Seaweed Communities in Retreat from Ocean Warming

In recent decades, global climate change [1] has caused profound biological changes across the planet [2-6]. However, there is a great disparity in the strength of evidence among different ecosystems and between hemispheres: changes on land have been well documented through long-term studies, but similar direct evidence for impacts of warming is virtually absent from the oceans [3, 7], where only a few studies on individual species of intertidal invertebrates, plankton, and commercially important fish in the North Atlantic and North Pacific exist. This disparity of evidence is precarious for biological conservation because of the critical role of the marine realm in regulating the Earth's environmental and ecological functions, and the associated socioeconomic well-being of humans [8]. We interrogated a database of >20,000 herbarium records of macroalgae collected in Australia since the 1940s and documented changes in communities and geographical distribution limits in both the Indian and Pacific Oceans, consistent with rapid warming over the past five decades [9, 10]. We show that continued warming might drive potentially hundreds of species toward and beyond the edge of the Australian continent where sustained retreat is impossible. The potential for global extinctions is profound considering the many endemic seaweeds and seaweed-dependent marine organisms in temperate Australia.

Inhibitory effect of Jeju endemic seaweeds on the production of pro-inflammatory mediators in mouse macrophage cell line RAW 264.7

Seaweed has been used in traditional cosmetics and as a herbal medicine in treatments for cough, boils, goiters, stomach ailments, and urinary diseases, and for reducing the incidence of tumors, ulcers, and headaches. Despite the fact that seaweeds are frequently used in the practice of human health, little is known about the role of seaweed in the context of inflammation. This study aimed to investigate the influence of Jeju endemic seaweed on a mouse macrophage cell line (RAW 264.7) under the stimulation of lipopolysaccharide (LPS). Ethyl acetate extracts obtained from 14 different kinds of Jeju seaweeds were screened for inhibitory effects on pro-inflammatory mediators. Our results revealed that extracts from five seaweeds, Laurencia okamurae, Grateloupia elliptica, Sargassum thunbergii, Gloiopeltis furcata, and Hizikia fusiformis, were potent inhibitors of the production of pro-inflammatory mediators such as nitric oxide (NO), prostaglandin E(2) (PGE(2)), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha). Based on these results, the anti-inflammatory effects and low cell toxicity of these seaweed extracts suggest potential therapeutic applications in the regulation of the inflammatory response.

Seasonal light and temperature responses of Caulerpa taxifolia from the northwestern Mediterranean

Seasonal light requirements and temperature tolerance of the Mediterranean green alga Caulerpa taxifolia (Vahl) C. Agardh were examined by means of photosynthetic assays. Highest photosynthetic rates (Pmax) were obtained in late fall (17.9 mg O2 g−1 organic dry weight h−1), while low values were observed from January to April (7.2-4.0 mg O2 g−1 organic dry weight h−1). Caulerpa taxifolia displayed low saturation and compensation points (68–166 mmol m−2 s−1 and 1.8–11.5 mmol m−2 s−1, respectively) and high efficiency at low incoming photon flux densities (0.077–0.197 mg O2 g−1 organic dry weight h−1 / μmol m−2 s−1). Estimated potential depth-limits of colonisation for this species are around 80 m in the extremely clear waters of the central Mediterranean and 50 m in the more turbid waters of the Gulf of Lions (northwestern Mediterranean). Photosynthesis at saturating photon flux densities (Pmax) was positive in the range of temperatures from 10 to 35°C, but negative at 40°C. In summer, Pmax values were similar from 20–30°C (10.7 mg O2 g−1 organic dry weight h−1), while in winter a maximum of 16 mg O2 g−1 organic dry weight h−1 was observed at 25°C. These results indicate that Caulerpa taxifolia is well adapted to light and temperatures that are typical of the infralittoral and upper circalittoral zone in the Mediterranean. Its annual productivity pattern seems less affected by seasonal fluctuations in light and temperature than has been reported for endemic seaweeds. This particular response may enable Caulerpa taxifolia to outcompete endemic species and explain its potentially high invasive capacity.