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Marine algae have been played an important role in human life since 3000 BC, with their nutritional and therapeutic values. In recent years, the role of marine algae in various industrial, agricultural and therapeutic applications have been further enhanced with their ability to biosynthesize nanoparticles. In this work, we tried to shed some light on different traditional and biotechnological applications of marine algae in modern life, particularly their utilization in the wider applications of nanotechnology.

Biosynthesis of silver nanoparticles (AgNPs) is emerging as a simple and eco-friendly alternative to conventional chemical synthesis methods. The role of AgNPs is expanding as antimicrobial and anticancer agents, sensors, nanoelectronic devices, and imaging contrast agents. In this study, biogenic AgNPs were synthesized using extracts of different marine algae species, including Ulva rigida (green alga), Cystoseira myrica (brown alga), and Gracilaria foliifera (red alga), as reducing and capping agents. The Physiochemical properties, cytotoxicity, anticancer and antimicrobial activities of the biosynthesized AgNPs were assessed. Surface plasmonic bands of the biosynthesized AgNPs capped with U. rigida, C. myrica, and G. foliifera extracts were visually observed to determine a colour change, and their peaks were observed at 424 nm, 409 nm, and 415 nm, respectively, by UV–Vis spectroscopy; transmission electron microscopy (TEM) indicated an almost spherical shape of AgNPs with nanoscale sizes of 12 nm, 17 nm, and 24 nm, respectively. Fourier transform-infrared (FTIR) spectroscopy analysis suggested that different molecules attached to AgNPs through OH, C=O, and amide groups. The major constituents of the aqueous algal extracts included, terpenoids, polyphenols, sulfonates, polysaccharides, fatty acids, chlorophylls, amide proteins, flavonoids, carotenoids, aliphatic fluoro compounds, volatile compounds, alkalines, pyruvic acid and agar groups. The cytotoxicity and anticancer activities of the biosynthesized AgNPs were assessed using Artemia salina nauplii, normal skin cell lines (HFb-4), and breast cancer cell lines (MCF-7 cell line). The lethality was found to be directly proportional to the AgNP concentration. The IC50 values of C. myrica and G. foliifera AgNPs against A. saline nauplii were 5 and 10 μg ml−1 after 4 h and 16 h, respectively, whereas U. rigida AgNPs did not exhibit cytotoxic effects. Anticancer activity of the biosynthesized AgNPs was dose dependent. The IC50 values of the biosynthesized AgNPs were 13, 13, and 43 µg ml−1 for U. rigida, C. myrica, and G. foliifera, respectively. U. rigida AgNPs particularly exhibited potent anticancer activity (92.62%) against a human breast adenocarcinoma cell line (MCF-7) with high selectivity compared the normal cells (IC50 = 13 µg/ml, SI = 3.2), followed by C. myrica AgNPs (IC50 = 13 µg/ml, SI = 3.07). Furthermore, the biosynthesized AgNPs exhibited strong antifungal activity against dermatophyte pathogenic moulds and mild antibacterial activity against the food borne pathogen bacteria. The highest antimicrobial activity was recorded for the U. rigida AgNPs, followed by those capped with C. myrica and G. foliifera extracts, respectively. AgNPs capped with the U. rigida extract exhibited the highest antimicrobial activity against Trichophyton mantigrophytes (40 mm), followed by Trichosporon cataneum (30 mm) and E. coli (19 mm), with minimal lethal concentration of 32 and 64 μg ml−1 respectively. The study finally revealed that extracts of marine algal species, particularly U. rigida extracts, could be effectively used as reducing agents for the green synthesis of AgNPs. These AgNPs are considered efficient alternative antidermatophytes for skin infections and anticancer agents against the MCF-7 cell line.

In spite of the established nutritive value of seafood, fishes have a special ability to store some toxic substances such as heavy metals because of its own respiration system. The goal of current study was to explore the proximate chemical composition, minerals content and levels of heavy metals in edible portions of some important commercial fish species available at Makkah Central Fish Market, Saudi Arabia. The obtained results showed that Indian oil sardine fish had the highest value of crude oil (dry weight) recorded 38.00%, while, rusty parrot fish sample had the least of 1.17%. In contrast, rusty parrot fish had the highest value of crude protein represented 90.75% (dry weight), meanwhile, Indian oil sardine had the least of 54.19%. Consuming about 250 g of Indian oil sardine will cover 100% of Fe RDA (Recommended Dietary Allowances), eating 500 g of the same fish will cover about 30% of Ca RDA. While, 500 g of gilt head bream which has the highest content of K, Na and Mg will cover about 11.7%, 1.5% and 4.1% of these minerals RDA, respectively. As physical hazards, fourteen samples from the thirty three studied samples exceeded the permissible limit of Pb and Cd representing about 42%. Therefore, it is strongly recommended not to eat head, gills or viscera of all fishes.

Fucoidan is sulfated polysaccharide extracted from seaweed brown algae. This study was designed to evaluate the immunomodulatory effects and disease resistance of dietary fucoidan on catfish, Clarias gariepinus, immunosuppressed by cadmium. Three hundred and sixty African catfish, C. gariepinus, was allocated into six equal groups. The first group served as a control. Groups (F1 and F2) were fed on fucoidan supplemented ration at concentrations of 4 and 6g/kg diet respectively for 21 days. Groups (Cd, CdF1 and CdF2) were subjected throughout the experiment to a sub-lethal concentration of 5ppm cadmium chloride solution and groups (CdF1 and CdF2) were fed on a ration supplemented with fucoidan. Macrophages oxidative burst, phagocytic activity percentages and lymphocytes transformation index were a significant increase in the fucoidan-treated groups (F1 and F2), while serum lysozyme, nitric oxide and bactericidal activity were enhanced only in group (F2) when compared with controls. These parameters as well as absolute lymphocyte count and survival rate were significantly increased in group (CdF2) when compared with cadmium chloride immunosuppressed group (Cd). It could be concluded that the fucoidan can be used as immunostimulant for the farmed African catfish, C. gariepinus as it can improve its resistance to immunosuppressive stressful conditions.

Two new glycerides, didemnacerides A (1) and B (2), together with three known sterols, 24-ethyl-25-hydroxycholesterol (3), cholest-6-en-3,5,8-triol (4) and cholestane-3β,5α,6β-26-tetrol (5), were isolated from the Red Sea ascidian Didemnum sp. Their structures were elucidated by using extensive 1D (1H, 13C) and 2D (1H–1H COSY, HSQC and HMBC) NMR studies and mass spectroscopic data (GC-MS and HR-MS) as well as alkaline hydrolysis followed by GC–MS and NMR spectral analyses of the fatty acid methyl esters. This is the first report of compounds 3–5 from the Red Sea ascidian Didemnum species.

Specimens of the star fish, Astropecten polyacanthus were collected monthly from the Great Bitter lakes and Lake Timsah during the period from1999 to 2001. Individuals of A. polyacanthus showed a sex ratio (males to females) of 1:1.34 and 1:0.97 in Great Bitter lakes and Lake Timsah respectively. The examination of reproductive data showed that individuals of A. polyacanthus spawned all the year around with peaks during spring and autumn. Oocyte size frequency distribution was similar in both lakes and the egg size ranged from 8 µ to 90 µ. All different sizes of oocytes were found all the year around with different proportions. Maximum fecundity (oocytes / female) reached 4800000 at Great Bitter Lakes and 7465860 at Lake Timsah. Fecundity showed exponential increases with the increase in body size, body weight and gonad weight.

Marine halophytes (mangroves and sea grasses) were collected from the Red Sea coast of Egypt and tested for their mosquitocid al activities. The toxicities of mangroves Avicennia marina & Rhizophora mucronata, and seagrasses Thalassodendron ciliatum, Halodule uninervis and Halophilia stipulacea were examined against lab. Strain of 3 rd instar larvae of Culex pipiens. Results showed that extracts of seeds and leaves of Avicennia marina were more effective than other parts of the same plant as well as of the leaves of Rhizophpra mucronata against 3 rd instar larvae of Culex pipiens mosquito. On the other hand, comparison of the tox icities of the three species of sea grasses showed that crude extract of Halodule uninervis was more active against 3 rd instar larvae of mosquito Cu pipiens than crude extracts of Thalassodendron Ciliatum and Halophilia stipulacea . In view of these results, the purified active compounds from the most effective s amples found in our studies could be effective in killing mosquito larvae or repellin g adult female mosquitoes in an economic and safe manner.

Zooplankton composition and abundance were investigated seasonally at ten sites in Lake Timsah and the adjacent, connected western lagoon in relation to the physico-chemical conditions. A total of 42 taxa (including larval stages) were identified, among them 21 species of copepods, 6 rotifers, 5 cladocerans, 1 chaetognath and 1 urochordate. Copepods represented the predominant component (77.7% of the total community), followed by rotifers, molluscs, cladocerans and (9.2, 4.7 and 3.9% respectively), while other groups collectively formed about 4.5% of the total zooplankton population. Summer was the most productive season with an average count of 40 864 individuals m-3. The dominant copepod species were Paracalanus crassirostris and Oithona nana representing 28.3 and 24.3% of the total zooplankton respectively. The total zooplankton count, including copepods, and its dominant species showed significant positive correlations with temperature, pH and total phytoplankton density. However, negative correlations were detected between densities of rotifers, and salinity and dissolved oxygen.

he population of the portunid crab Charybdis natator in the Gulf of Suez, Red Sea was studied by monthly sampling from September 2007 to May 2008. Crabs were sexed, measured and berried females recorded. A total of 498 individuals were obtained, of which 232 (46.6%) were males, 212 non-ovigerous females (42.5%), and 54 (10.9%) ovigerous females. The overall sex ratio (M:F) was (1:1.1) and females outnumbered females during September-November. The population showed sex differences in the size frequency distributions, with males reaching larger size than females (70-148.4mm and 47.5-130.5mm CW, respectively). Ovigerous females existed all year round and ranged in size between 83-118.4mm CW. Fecundity ranged from 45230 to 335529 eggs per female and was positively correlated with body size. The effectiveness of the closed season that runs in the Gulf of Suez on the population of C. natator was discussed.

his study was conducted on a naturally growing mangrove population at Ras Mohammed and Nabq protected areas, South Sinai, during the period 20052006. Avicennia marina is the only growing mangrove species in South Sinai. Its structure, litterfall and seedling distribution were investigated. The total area of mangrove stands is 99.1 hectares with 42% canopy coverage, average tree height is between 1.7 - 2.6 m, basal area up to 9.2 m 2 . ha -1 . Ras Mohammed represents the densest stand (428 stems ha -1 ). An annual litterfall of 2036.7 Kg. ha -1 . yr -1 was recorded at Rowaiseya with a maximum peak during April. Mangroves at Nabq area have well distribution of seedlings over Abu Zabad site and a localized dense aggregation of seedlings in intertidal areas at Monqataa and Gharqana sites with a seedling density up to 1848 ha -1 .

The serpulid polychaete Spirobranchus tetraceros of Red Sea / Indo-pacific origin, recently has succeeded to establish a foothold in Alexandria Mediterranean waters. Worms were monthly scraped from submerged iron substrates at Abu Kir Bay during the period December 2000 – November 2001. Both light and TEM were used to study gametogenesis and time of spawning of S. tetraceros.Gametogenesis was asynchronous and oogenesis could be divided into two previtellogenic, two vitellogenic and a spawning stage. Oocyte development took about 8 months, from October to June. Spawning occurred from late May - early June until October. Thus S. tetraceros is a long period spawner. The maximum diameter of ripe oocyte is 78 mm. The spermatogenic phase could be divided into three stages: spermatogonia, spermatocytes and spermatids (including spermatozoa). The duration of sperm development took about 8 months. Spermatocytes persist from October to March. By March the sperms grew rapidly until they became spermatozoa in May. The sperm could be considered ect-aquasperm with regard to its fertilization biology.

خلال فترة التلوث البترولي لشرم المية عام 1999م ، تم دراسة التركيب النوعي وكثافة كل من الحشائش واللافقاريات البحرية في مناطق مختلفة " ملوثة وغير ملوثة بالبترول " في جونة شرم المية. حيث وجد أن أكثر الحشائش انتشارا وكثافة هو الهالوفيلا استيبولاسا الذي ينمو بعمق 1ـ3 متر على التربة الرسوبية لهذه الجونة. وقد تراوح المحصول القائم ما بين 25-280جرام كتلة جافة / م2. ولقد أوضح الشكل الظاهري وعلامات النمو الجنسي ( التزهير) أن حقول هذا النوع من الحشائش في المناطق المختلفة من الجونة صحية ولم تتأثر بالتلوث البترولي وتنمو بطريقة عادية. ولهذا اعتمادا على هذه المعلومات فلقد أشار البحث إلى أن النباتات المكونة لمجتمع الحشائش البحرية بشرم المية لم تعاني أي تدهور نتيجة للتلوث البترولي الذي حدث، بينما أظهرت اللافقاريات القاطنة له تدهورا في التركيب النوعي والكثافة.

Pneumatophores of the mangrove trees Avicennia marina along the Egyptian Red Sea coast were investigated, to measure the spatial variability in their epiphytic community. Forty eight species of epiphytes (36 algae and 12 invertebrates) were recorded all over the investigated sites. With the resulting data being subjected to comparison indices (Jaccard), the more adjacent sites were the more similar in their biotic contents. This spatial variability is not a geographical trend but it could be attributed to the abiotic and biotic components characteristic to each site.

The sea bream Lethrinus nebulosus was sampled during the spawning season of 1996 (May-July) in Ras Mohamed Marine Park. Out of 119 specimens collected (46 females and 73 males), 11 females (23.9 %of examined females) were found to be parasitized by unidentified nematode. This parasite is found to be specific for fish ovary, causing a reduction in the absolute fecundity of the infected females compared with normal ones (averaged 4.97 x 105 and 7.54 x 10 5 eggs/female, respectively).In all infected females, 2-4 nematode worms of 30-40cm in length / each ovarian lobe, were coiled together in a mass occupying the ovarian lumen and seemed to block the oviduct preventing egg releasing. Histological examination showed that ovaries of heavily infected females did not contain mature ova with a depression of the vitellogensis process. All infected ovaries were characterized by certain degrees of atresia depending upon the level of infection. The synchronization between reproduction of the fish and the parasite, and the parthenogenetic nature of the parasite are thought to increase the biological potential of the parasite to colonize and infect other host individuals and possibly other populations.

A study was made from January 1988 to March 1989 of the penaid prawns in the Great Bitter Lake and Lake Timsah located in the central part of the Suez Canal. Two species of Red Sea origin were investigated,Metapenaeus stebbingi andTrachypenaeus curvirostris; the former is by far the commoner. Both species displayed seasonal breeding over the period April to October, with peaks in the early and late parts of the season.M. stebbingi had two main cohorts each year. A spring-spawned cohort survived 16 mo, and attained modal sizes of 23 mm carapare length (CL) for females and 16 to 17 mm CL for males. The autumn-spawned cohort survived 13 mo, and reached modal sizes of 20 mm and 15 mm CL for males and females, respectively. The reasons for the success ofM. stebbingi in the Canal lakes, in contrast to other “Lessepsian” penaeids which have flourished in the Mediterranean Sea, have been considered. The main factors are that it is essentially a shallow-water species, with excellent tolerance of salinity variations and adverse environments. However, the Canal lake populations have smaller maximum sizes, and mature earlier, than those in open seas.