Screening and formulation of chemoattractant coatings for artificial reef structures.

This study was carried out to augment the colonization of marine benthic communities on artificial reef structure. Increasing marine pollution along with various natural hazards cause severe damages to marine algae and associated fauna. In recent years, artificial reefs have been deployed in coastal regions of several parts of the world in order to increase the marine productivity. They are mainly built with concrete materials, however their leachates have considerable impacts on algae. Therefore to increase the algal colonization five chemoattractants such as ferrous sulfate, zinc oxide, ammonium nitrate, sodium phosphate and ferrous lactate were screened against spores of a fouling alga, Ulva pertusa. FeSO4 / ZnO (8:2) and ferrous lactate coatings showed the highest spore attachment with 52 +/- 5.2 cm2 and 79.5 +/- 10.2 cm2 spores respectively (p<0.01). Furthermore using these chemoattractants, coating formulations were made and their performances were investigated at East coast (Ayajin harbor) and South coast (Meejo harbor) of Korea. A maximum fouling coverage (with green algae 25%, red algae 11.3% and brown algae 63.7%) was estimated from ferrous lactate coatings (p<0.01). Different composition of coating formulations and their chemoattractive properties were evaluated.

Biophoton emission of MDCK cell with hydrogen peroxide and 60 Hz AC magnetic field.

We studied biophoton characteristics of Madin-Darby canine kidney (MDCK) cells under the influence of H2O2 by employing a photomultiplier tube (PMT) and a fluorescence microscope. H2O2 was used for producing reactive oxygen species (ROS) in the measurement. Images from a fluorescence microscope show an increase of photon intensity emitted from the sample due to H2O2. By using a PMT we measured quantitative change in biophoton emission with application of H2O2 to the MDCK cell culture, found that the increase of the biophoton is dependent upon the amount of H2O2. The agreement between the results of the PMT and the fluorescence microscope suggests the possibility of quantitative measurement of the influence of ROS on living tissue or cell. In addition we applied a 60 HzAC magnetic field on the cells to investigate the change in reaction between MDCK cell and ROS. It showed that a decay of chemiluminescence intensity has taken a different path following exposure to the magnetic field. As a result, the PMT measurement might be considered as a useful tool for studying biochemical characteristics in relation to ROS.

Effects of tributyl-tin on a marine microalga, Tetraselimis suecica.

Marine pollutants induce changes in microalgal metabolism. In this study effects of tributyl-tin chloride (TBTCl) on a marine microalga Tetraselmis suecica was studied. The changes induced by TBTCI on growth rate, viability and biochemicals were assessed. In acute exposure to TBTCl, EC50 estimated for 24 hr was 2.02 microg ml(-1), whereas total lethality was observed at 4 microg ml(-1). In chronic exposure to TBTCl, at higher concentrations (0.5-1 microg ml(-1)) growth rate, chlorophyll pigments, carbohydrate and protein contents were reduced. The results of this study indicate that TBTCl toxicity made drastic changes in growth and biochemical composition of T. suecica.

Biofouling attractants from a brown marine alga Ecklonia cava.

In recent years, industrial pollutants and the mountain forest fire ashes released into seawater cause damage to the marine environment, mainly it reduces the algal productivity in the inter tidal region. To get recover from the stress due to pollutants and to increase the growth and development of biofouling algae (benthic organisms), Ecklonia cava extract was investigated for its biofouling attracting efficiency. Bioactive guided fractions of E. cava extract derived from column chromatography were tested against spore attachment of a fouling alga, Ulva pertusa. Fraction B showed increased spore attachment rate with a maximum of 92 +/- 5%. This fraction was further analysed on HPLC, GC-Mass and NMR, deduced as pentadecanoic acid.

Influence of five organic antifouling candidates on spore attachment and germination of a fouling alga Ulva pertusa.

Screening of test chemicals or formulations for antifouling (AF) activity is important to get first hand information on their nontoxic repelling activities. Especially spores of a fouling alga, Ulva pertusa were used in this study to test the AF efficiency of five organic chemicals. Coatings made with 100 microg cm2 of citral and eugenol significantly inhibited the spore attachment. A low concentration (1 microg cm2) of solanesol exhibited effective AF activity against spore attachment. Spore germination was sensitive to different AF candidates screened in this study. Based on the attachment and germination response of Ulva pertusa spores, AF efficiency of five organic AF candidates is discussed.

Effects of copper (I) oxide on growth and biochemical compositions of two marine microalgae.

In copper based antifouling (AF) paints Cu (I) oxide was largely used as booster biocide. In this study effect of Cu (I) oxide on two marine microalgae, Tetraselmis suecica and Dunaliella tertiolecta was demonstrated. EC50 (96 hr) concentrations estimated for T. suecica and D. tertiolecta were 1.3 mg l(-1) and 1.34 mg l(-1), respectively. Copper (I) oxide induced changes in growth, chlorophyll, carbohydrate and protein contents were observed in T. suecica and D. tertiolecta. At low concentration of 0.0625 mg l(-1), 3-26% and 1-16% growth stimulation was observed in T. suecica and T. tertiolecta respectively. Increasing Cu (I) oxide concentrations proportionately decreased the carbohydrate and protein contents. This study clearly indicates the toxicity of excessive Cu (I) oxide on growth and biochemical compositions of T. suecica and D. tertiolecta.

Use of sodium transfer tissue biosensor (STTB) for monitoring of marine toxic organism.

A highly sensitive sodium (Na+) transfer tissue biosensor (STTB) was designed using a frog bladder membrane to measure paralytic shellfish poisons (PSP). The STTB consists, of a Na+ electrode covered by the membrane, which was then integrated into a flow-through system for continuous measurements. In the absence of Na+ channel blocker, active transfer of Na+ occurred from inside to outside across the frog membrane. When the STTB was used to measure the Na+ -dependent dissociation of PSP, it was able to detect PSB at a level contained in a single cell. However, 5 fg or higher (100 cells or more) is needed for accurate and reproducible measurements. The toxicity obtained by the STTB was significantly correlated (r = 0.9449) to that determined by the HPLC. Therefore, the simple method of the STTB can be used not only to detect a low level PSP in toxic plankton populations, but also to monitor poisons in shellfish.

Effects of basic oxygen furnace slag and inorganic nutrients on the germination of resting cysts of two toxic dinoflagellates.

Effects of basic oxygen furnace (BOF) slag, inorganic nutrients and H2S on the germination of resting cysts of two toxic dinoflagellates Alexandrium catenella/tamarense and Gymnodinium catenatum were studied in batch cultures. The germination rate of the test species has increased by 23-25%, when the concentration of NO3--N or H2S in culture medium has increased to 2.0 ppm. At the treatment of enriched NH4+-N and PO43--p, the germination of resting cyst was increased. Nevertheless, the increased range in germination rates was less than those of NO3--N and H2S. When BOF slag in culture medium increased to 50 mg/ml (or 500 g/m2), the cyst germination rate fell to less than 5%. At higher level of concentrations germination was completely inhibited. Adding BOF slag to the culture medium reduced the concentration of inorganic salts and H2S in seawater and sediments, resulting in the inhibition of cyst germination. These findings demonstrate the potential use of BOF slag on the sediments seed bank of red tide organism because it has an ability to inhibit resting cysts germination.

Minimum effective release rate of antifoulants.1. Effects of zosteric acid at Ford Island, Hawaii (USA).

Minimum effective release rate (MERR) of zosteric acid (ZA) was studied at Ford Island. At laboratory condition, spore attachment in Enteromorpha intestinalis was inhibited significantly at 28.2 microg cm2 of ZA. More than 95% reduction in spore attachment was achieved in Ulva fasciata at 2,000 microM of ZA through membrane diffusion system. At 40 cm depth level larval settlement was high with maximum number of Hydroides elegans settlement. The overall larval settlement was increased with increasing days of exposure. The MERR of 10 microg cm(-2) d(-1) ZA inhibited 50% of the larval settlement. However, the inhibition rate was not proportionate to the antifouling ZA concentration. Using MERR membrane diffusion system an effective antifouling strategy was suggested for Ford Island.

Antifouling activity of six nontoxic chemicals on spore attachment of Ulva fasciata.

Marine biofouling cause severe damage to all marine technologies. Indiscriminate use of toxic metallic antifouling (AF) chemicals (cuprous oxide and TBT) to control the biofouling in turn greatly affects the flora and fauna of the marine ecosystem. In search of environmentally safe and effective AF agents, six nontoxic AF candidates were studied against the spore attachment of Ulva fasciata. Spore attachment was inhibited at 100 microg of trans-cinnamic acid (TCA) and benzoic acid (BA). Sulfate-coumaric acid (SCA) had no significant effect on the spore attachment. The release rate of BA exhibited a constant release flow. Varied response of U. fasciata spores to AF chemicals and release rate to the surrounding medium are discussed.