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Background Seaweeds harbour a wide array of bioactive compounds shown to be effective in support of sustainable agricultural practices. The green seaweed Chaetomorpha antennina found in abundance in coastal areas of India has been reported with various bioactivities. Owing to the requirement of alternative and economical natural pest control method to be applied in sustainable agronomic strategies, the current study attempts to evaluate the efficacy of chemical toxins from C. antennina, as insecticidal agents, by inspecting their effects on the physiology, biochemistry, immune system, and histology of one of the most important insect pests of agricultural crops in the Asian tropics, the polyphagous lepidopteran Spodoptera litura. Results The active fraction 5 isolated from C. antennina using methanol extraction produced significant mortality rates of S. litura among all the other fractions obtained. GC–MS analysis revealed the presence of various pesticide compounds. The toxin compounds (active fraction 5) were found to negatively influence the pest’s immune system performance at sub-lethal concentrations (LC50 38.73and LC90 53.60 ppm), affecting insect development, reducing the haemocyte count (69.24%) and reduced the activity of major defence enzyme phenoloxidase decreased post-treatments. Digestive phosphatase enzymes, acid phosphatase, ACP, alkaline phosphatase, ALP, and ATPase were demodulated by 37.5, 39, and 23.9% compared with untreated. Increase in detoxification enzymes coupled with mid-gut collapse are indicative of the toxicity of the compounds. Earthworms exposed to seaweed compounds displayed no debarring effects. Conclusion Extracted seaweed compounds produced significant lethal effect on the insect larvae, affecting the immune as well as digestive systems of the pest. However, no such toxicity was observed in earthworms treated with the seaweed fraction supporting their environmentally benign nature. Since the insect immune system is responsible for the development of resurgence against pesticides, suppression of immunological activities by seaweed toxins indicate the long-term applicability of these compounds as prospective pesticides. The results support the potential of chemicals from C. antennina for biopesticide development to manage economically important agricultural pests.

Laboratory experiments were conducted to investigate the effect of copper enrichment (0.6, 2, 4, 8, 18 and 36 μg L−1) and salinity (8.5, 17 and 24%) on growth, photosynthetic efficiency “PE” (expressed as chlorophyll fluorescence) and copper accumulation in germlings and adult brown alga Fucus ceranoides. The PE for the algae exposed to 17% salinity was markedly stable throughout the experiment, while it was significantly (0.01 ˂ p ˂ 0.05) reduced in algae exposed to 8.5% salinity in the presence of 36 μg L−1 Cu by 20% when compared to those exposed to 0.6 μg L−1 Cu. Moreover, the maximum electron transport rate (ETRmax) was decreased significantly with increasing concentrations of Cu (p ˂ 0.001) and level of salinity (p ˂ 0.01); moreover, there was a significant interaction between Cu and salinity. The combination of copper and reduced salinity gave synergistic effects, as a consequence, this could limit the population growth of seaweeds in coastal areas. More research is needed to understand the basic requirements and stress tolerance in seaweeds for reef restoration and other management actions to be successful for sustainable development.The results of the present study suggest that any change in the environment will directly and significantly affect algal physiology, and thus it could be used for biomonitoring in situ. Moreover, the assessment of the physiological status of algae in combination with the analysis of thallus metal content will improve the trustworthiness of the biomonitoring process.

ACTIVITIES of superoxide dismutase (SOD), catalase (CAT) and peroxidase (GR), lipid peroxidation (expressed as MDA), the accumulation of H2O2, and photosynthetic activities in Ulva lactuca (Ulvales, Chlorophyta) were determined in the present study in order to investigate their response to polyaromatic hydrocarbons (PAHs) at residential and industrial sites in Alexandria, Egypt.Increasing in PAHs concentrations caused significant (P˂ 0.01) inhibition in the activities of SOD and CAT by 32% each, while, the activity of GR was significantly increased by 1-fold (P≤ 0.001). MDA levels were increased with increasing concentrations of PAHs; however, their levels were inversely proportional to activities of antioxidant enzyme (especially CAT). Moreover, photosynthetic rates (Pn), chlorophyll fluorescence (Fv/Fm), and total chlorophyll were significantly reduced (P˂ 0.01) with increasing PAHs by 24, 25, and 19%, respectively. The apparent increase in GR activity could indicate that alga acclimatized to the oxidative stress of PAHs, although oxidation of membrane lipids was not totally prevented, as indicated by stimulated MDA levels.The results indicated that PAHs could exert oxidative damages, and the harmfulness occurred mainly in samples collected from the industrial site with higher concentrations of PAHs. To the best of our knowledge, this is the first study to investigate the novel and conventional effects of PAHs on the physiological and biochemical traits of alga.

Plastic pollution and its impact on marine ecosystems are major concerns globally, and the situation was exacerbated after the outbreak of COVID-19. Clean-up campaigns took place during the summer season (June–August 2020) in two coastal cities in Egypt (Alexandria and Hurghada) and Jeddah, Saudi Arabia to document the abundance of beach debris through public involvement, and then remove it. A total of 3673, 255, and 848 items were collected from Alexandria, Hurghada, and Jeddah daily, respectively. Gloves and face masks (personal protective equipment “PPE”) represent represented 40–60% of the total plastic items collected from each of the three cities, while plastic bags represented 7–20% of the total plastics litter collected from the same cities. The results indicated the presence of 2.79, 0.29, and 0.86 PPE item m−2 in Alexandria, Hurghada and Jeddah, respectively. This short focus provides an assessment of the environmental impacts of single-use gloves and masks used for COVID-19 protection from June to August 2020. To the best of our knowledge, this study presents the first such information from the Middle East, specifically Egypt and Saudi Arabia. It highlights the need for further knowledge and action, such as safe, sustainable, and transparent waste management processes related to COVID-19 to reduce the negative impacts now, as well as in future events. Furthermore, this study helps in achieving key components of the United Nation's Sustainable Development Goals (SDGs). This short focus can serve as a multipurpose document, not only for scientists of different disciplines but for social media and citizens in general.

The uptake of fast orange dye by the red seaweed Laurencia papillosa has been demonstrated in order to explore its potential use as low-cost adsorbent. The adsorption kinetics of fast orange dye on the alga with respect to initial dye concentration, contact time, particle size and pH were investigated. The dye removal percentage increased from 25.92 to 67.08% and the equilibrium states were attained at almost 60 min within the experimental concentration range. The adsorption kinetic was analyzed using pseudo-first-order and pseudo-second-order models. The pseudo-second-order model was more appropriate to describe the sorption kinetics based on the relatively high values of the linear squared regression correlation coefficient. The nature of the possible adsorbent and fast orange interactions was examined by the Fourier transform infrared technique. This technique confirmed that hydroxyl, carboxyl, amine, sulfonyl, carbonyl and alkyl groups are responsible for the dye binding process. Significant increase in dye adsorption was observed with the decrease in sorbent particle size coupled with its large surface area. Maximum removal efficiency was determined to be 65.7% at a solution pH of 5. However, Laurencia papillosa proved to be a promising material for removing fast orange dye from aqueous solutions. Keywords: Dye adsorption, Macroalga, Laurencia papillosa , kinetics African Journal of Biotechnology Vol. 12(17), pp. 2215-2223

This study discusses the perspectives regarding the green alga Dunaliella salina Toed for biodiesel manufacturing purposes. The alga was cultivated under controlled lab conditions. Biomass concentration at early stationary grown microalga was 2.6 mg/L dry weight, while the algal oil was about 27.1% of the biomass. Algal oil was esterified and analyzed using GLC technique. Fourteen fatty acid methyl esters were identified. The amount of saturated and unsaturated fatty ester fractions was 35% and 65% respectively. The physicochemical properties of fatty acids comprising biodiesel were discussed. However, culture optimization coupled with genetic improvement will definitely represent contributions to bring about innovation in oil hyper-producing D. salina that will ultimately meet with success.

Background This batch study deals with the relation between lipid as well as triglyceride contents in Nannochloropsis salina and variation in culture conditions such as nitrogen concentration and temperature. Results The tested parameters caused reduction in growth expressed as cell count, optical density and dry weight, as well strongly involved in lipids and triglycerides accumulation and significantly affected the lipid productivity. At the beginning of the work, the concentration of nitrogen in the medium was reduced to three quarter, half and quarter of the original f2 medium while the temperature kept constant. After that, the optimal nitrogen concentration (quarter of the original media) giving high lipid yield was tested with different temperature degrees from 15 to 35°C with five degree intervals. Although the growth was insignificantly influenced, a considerable increase in lipid and triglyceride (56.1 and 15.1% of dry weight respectively) was observed when the concentration of nitrogen in the medium was reduced to the quarter. Moreover, 59.3% lipid and 17.1% triglyceride on the basis of dry weight were obtained by the combination of 25% nitrogen concentration and 30°C. Simple regressions recommended that the interaction effect of nitrogen limitation and temperature on lipid and triglyceride accumulation was not as fundamental as for nitrogen limitation stress. Conclusion The degree of nitrogen availability in the combination of temperature effect has been identified as the critical determinant for the maximal production of lipid in N. salina. Nevertheless, major advances in this field can be considered by studying more stresses techniques and genetic strategies. Electronic supplementary material The online version of this article (doi:10.1186/s40529-015-0085-7) contains supplementary material, which is available to authorized users.