Running Sea Water Research Articles

Acidifier supplementation in low-fish meal diets improved growth performance and health indices in Asian seabass (Lates calcarifer) juveniles

A feeding trial was done for 60 days to examine the influence of supplementing low-fish meal (FM) diet with a mixture of acidifiers on the performance of Asian seabass (Lates calcarifer) juveniles (initial weight: 54.2 ± 0.5 g, mean ± standard deviation). Dietary FM was replaced (35% and 70%) with a mixture of alternative protein sources, including soybean meal, corn gluten, wheat gluten, and poultry meal then supplemented with two levels (0.5% and 1.0%) of an acidifier mixture (butyric acid, sodium diformate and fulvic acid, 1:1:1 ratio). In this regard, seven isonitrogenous (45%) and isolipidic (15%) diets were formulated including: FM70 (FM-based diet, control), FMR35 (35% FM replacement), FMR35+0.5% (35% FM replacement + 0.5% acidifier mixture), FMR35+1.0% (35% FM replacement + 1.0% acidifier mixture), FMR70 (70% FM replacement), FMR70+0.5% (70% FM replacement + 0.5% acidifier mixture), and FMR35+1.0% (70% FM replacement + 1.0% acidifier mixture). Fish were stocked into twenty-one 2000-L rectangular concrete tanks (53 fish/tank) that were filled with running seawater in a flow-through system (26.5 ± 1.5 °C and 46.0 ± 0.2 ppt). Fish were fed with the diets twice every day up to visual satiation. Before the beginning (day 0), middle (day 30), and after finishing the feeding trial (day 60), fish were individually weighed, and samples were collected from their blood and gut for evaluating hematological, antioxidant and digestive enzymes, respectively. After finishing the feeding trial, fish fed FMR70 had lower weight gain (89.1% lower than FM70) than other groups (P = 0.001) that associated with the lowest feed intake in this group. The trypsin, protease, and α-amylase activities were decreased by increasing FM replacement level, but it enhanced alkaline phosphatase activity (P < 0.05). Serum catalase activity increased by the interactive effects of dietary FM replacement and acidifier level (P = 0.029). The blood hemoglobin, mean cell volume, mean cell hemoglobin, lysozyme activity, serum protein, albumin, globulin, cholesterol, and triglycerides increased by including a 0.5% acidifier mixture in the low FM content diets (P < 0.05). In addition, serum calcium content increased with increasing acidifier mixture level in the diet (P = 0.006). In summary, the inclusion of 0.5% acidifier mixture in a low FM-diet not only improved growth performance and feed utilization but also promoted humoral immunocompetance and hematological indices in L. calcarifer juveniles.

Cultivating marine macroalgae in CO2-enriched seawater: A bio-economic approach

By the end of the current century atmospheric CO2 concentration may reach 1000 ppm, more than twice the present level set at ca. 400 ppm. Marine macroalgae (seaweeds) contribute to global primary production and by taking up CO2 they may ameliorate and regulate global climate change. Seaweeds also have direct and indirect economic importance by providing food and bioactive compounds for human benefit. Nonetheless, all these benefits could be jeopardized by the ongoing pressures, both local and global, on marine environments. In this study we examine the effects of dissolved CO2 and seasonal seawater temperature on the growth rates (measured weekly changes in biomass and expressed on a daily basis) of two model species, Ulva rigida (Chlorophyta) and Gracilaria conferta (Rhodophyta), which are common in the intertidal zone of the Israeli Mediterranean Sea, and cultivated by the local seaweed industry. The seaweeds were grown in land-based 40 L fiberglass tanks fertilized with sufficient N and P, supplied with running seawater and continuous air bubbling to keep equal exposure of the seaweeds to nutrients and light. The tanks were also provided with aeration with regular air (ambient CO2, ~ 400 ppm) or CO2-enriched air (~780 ppm). Seaweeds exposed to CO2–enriched seawater grew faster, 32.5 and 8.5% growth per day for U. rigida and G. conferta, respectively. Following calculations of productivity rates, market price, and input cost, we estimate production and show a quadratic production function with respect to temperature for each CO2 concentration. Thus, there is an optimal temperature that maximizes seaweed output. Based on the production function estimates and using market prices, maximal short-run profits were obtained at ca. 22.5 °C and 27.5 °C for U. rigida and G. conferta, respectively. These results may provide useful information for seaweed growers on what and where to grow seasonally, and how farming activities should adapt to external changes in temperature and CO2 concentration.

Using Seawater to Document Coral-Zoothanthella Diversity: A New Approach to Coral Reef Monitoring Using Environmental DNA

Frequent, high-density coral monitoring is essential to understand coral reef ecosystems. For this purpose, we developed a novel method for simultaneous monitoring of Acropora corals and their symbiont, Symbiodinium, from environmental DNA (eDNA) in seawater using next generation sequencing technology (NGS). We performed a tank experiment with running seawater using 19 Acropora species. Complete mitochondrial genomes of all the Acropora species were assembled to create a database and major types of their Symbiodinium symbionts were identified. Then eDNA was isolated by filtering inlet and outlet seawater from the tanks. Acropora and Symbiodinium DNA were amplified by PCR and sequenced. We detected all of the tested Acropora types from eDNA samples. Proportions of the DNA sequences and the weights of corals, and the number of DNA sequences and the masses of corals were positively correlated in the tanks, respectively. In this trial, we detected DNA sequences from as little as 0.04 kg of Acropora colony, suggesting that existence of at least one adult Acropora colony (approx. 30 cm diameter = 1kg) per m2 at depths <10m could be detected using eDNA in the field. In addition, we detected major types of Symbiodinium within host corals from seawater, suggesting that it should be possible to detect major coral symbiont types if Acropora corals exist nearby, and possible free-living state Symbiodinium cells from eDNA in sea water. eDNA abundance of Symbiodinium types did not correlate well with frequencies of major Symbiodinium types in the corals, suggesting that quantification of Symbiodinium is difficult at this stage. Although this is the initial attempt to detect coral and Symbiodinium simultaneously from eDNA in seawater, this method may allow us to perform high-frequency, high-density coral reef monitoring of both corals and their symbionts in the near future.

Immunocyto chemical Reactions in The Brittle-Star: Ophiocomina Nigra After Immunization

Immunisations of Ophiocomina nigra were performed with either Bovine Serum Albumine BSA or Horse Radish Peroxydase HRP in aquarium containing running sea water An immunocyto chemical test was done in presence of HRP diaminobenzidin H O for both animals Control ones BSA ones and HRP ones Positive reactions only occur in injected animals to HRP So the brittle star Onigra as the sea star Asterina gibbosa Discriminates HRP from BSA it is an antibody like reaction Plasmolymphocytic cells were evoked

Effects of dietary polyvinylchloride microparticles on general health, immune status and expression of several genes related to stress in gilthead seabream (Sparus aurata L.)

It is a long-recognized fact that marine plastic debris contaminates the oceans and seas of the entire world. Even though their effects on the aquatic biota are not well documented or understood. The effects of dietary polyvinylchloride microparticles (PVC-MPs) on the general health, immune status and some stress markers were studied using gilthead seabream (Sparus aurata) as a model of marine fish. Thirty specimens were randomly placed in three running sea water aquaria and fish in each aquarium received an experimental diet containing 0 (control), 100 or 500 mg kg−1 of PVC-MPs for 30 days. Metabolic parameters in serum indicated that the dietary intake of PVC-MPs negatively affected several vital organs. Humoral immune parameters were determined in serum and skin mucus. Cellular immune parameters were determined in head-kidney leucocytes. Concomitantly, the expression of different genes related to stress was studied in head-kidney and liver. Regarding head-kidney gene expression, prdx5 was significantly decreased by PVC-MPs intake for 15 and 30 days, respect to the values found in control fish. On the other hand, the expression of prdx1 and prdx3 were significantly increased by the PVC-MPs intake during 15 and 30 days, compared with the values found in control fish. Furthermore, the expression of hsp90 and ucp1 genes decreased and increased, respectively, in the liver of fish fed 500 mg kg−1 of PVC-MPs for 30 days. Although ingestion of PVC-MPs provoked few significant effects (mostly increases) in the main immune activities of gilthead seabream compared with the values found in control fish, PVC-MPs are recognized by the fish as stressors. Continued exposure of fish to high concentrations of PVC-MPs could have a negative impact on fish physiology due to the chronic stress produced.

Immunocytochemical Reactions in the Brittle-Star: Ophiocomina Nigra after Immunization

Immunizations of Ophiocomina nigra were performed with either Bovine Serum Albumine BSA or Horse Radish Peroxydase HRP in aquarium containing running sea water An immunocytochemical test was done in presence of HRP diaminobenzidin H O for both animals Control ones BSA ones and HRP ones Positive reactions only occur in injected animals to HRP So the brittle star O nigra as the sea star Asterina gibbosa discriminates HRP from BSA it is an antibody like reaction Plasmolymphocytic cells were evoked

Pharmacokinetics of Eugenol in Japanese Flounder, Paralichthys olivaceus

AbstractEugenol, which has been used as an anesthetic for fish, was administered to Japanese flounder, Paralichthys olivaceus (127 ± 50.8 g), by bath treatment at concentrations of 0.025, 0.125, and 0.25 mL/L seawater for 10 min and intramuscular injection at 40 μL/fish to investigate the pharmacokinetic characteristics of eugenol in the plasma of Japanese flounder. In the bath treatment test, plasma eugenol concentration increased with increasing eugenol concentration up to 0.125 mL/L and reached steady state within 5 min. After a 10‐min bath treatment in 0.25 mL/L eugenol, plasma eugenol concentration was about 58.4 µg/mL. After transfer into running seawater, plasma eugenol concentration decreased biphasically with half‐lives of 0.0296 h (α‐phase) and 0.289 h (β‐phase). The AUC0000→0800 was about 16.5 µg h/mL. In administration by intramuscular injection, plasma eugenol concentration increased rapidly after administration and decreased biphasically with half‐lives of 0.0329 h (α‐phase) and 8.08 h (β‐phase). The AUC0000→0800 was about 52.5 µg h/mL. In both methods of administration, Japanese flounder with average weight of 127 g were effectively anesthetized when plasma eugenol concentrations were between 2.19 and 4.88 µg/mL.

New record of the mangrove rivulid Kryptolebias hermaphroditus Costa, 2011 (Cyprinodontiformes: Cynolebiidae) in the Pará state, northern Brazil

The mangrove killifish Kryptolebias herma­phro­ditus is reported to the southeast and northeast regions of Brazil. Recently, a specimen of K. hermaphroditus was collected in a shallow running seawater stream at Ajuruteua beach, Pará state, northern Brazil. This new record is ca. 1,350 km from the nearest previously known occurrence in Rio Grande do Norte state, Brazil. Morphological, molecular, and ecological aspects of this species are described.

Reference intervals for haematological and plasma biochemical parameters in sobaity sea bream juveniles (Sparidentex hasta, Valenciennes 1830)

Sobaity sea bream (Sparidentex hasta) is distributed in the Western Indian Ocean, Persian Gulf and Oman Sea. For monitoring health status in this species in an aquaculture condition, standard reference values for haematological and plasma biochemical parameters are indispensable. Heparinized blood samples were collected from 143 healthy sobaity sea bream juveniles raised in cylindrical polyethylene tanks with filtered running seawater. Haematologic reference intervals were as follows: red blood cell (RBC) count 1.67–2.2 × 106 μL−1, total white blood cell (WBC) count 8.8–14.5 × 103 μL−1, lymphocytes 85–96 %, neutrophils 2–6 %, haemoglobin 28–60 g L−1, haematocrit (Hct) 24.5–33.8 %, mean cell volume (MCV) 126.3–191.7 fL, mean cell haemoglobin (MCH) 14.4–26.5 pg, mean cell haemoglobin concentration (MCHC) 92–180 g L−1, erythrocyte sedimentation rate (ESR) 1.5–5 mm h−1 and RBC/WBC ratio 119.2–207.5. Plasma chemistry reference intervals were as follows: total protein 3.2–3.9 g dL−1, albumin 0.3–0.58 g dL−1, globulin 2.7–3.4 g dL−1, alkaline phosphatase 444–866 U L−1, alanine aminotransferase 239–506.5 U L−1, lipase 95.5–120 U L−1, amylase 4–8 U L−1, sodium 173–211 mmol L−1, chloride 103–136.5 mmol L−1, potassium 2.7–4.4 mmol L−1, calcium 2.6–3.1 mmol L−1, inorganic phosphorus 2.9–5.3 mmol L−1, osmolality 430–503 mOsm kg−1, glucose 6.16–7.88 mmol L−1, cholesterol 4.07–7.7 mmol L−1, triglyceride 2.22–3.91 mmol L−1, high-density lipoprotein (HDL) 1.36–2.44 mmol L−1, low-density lipoprotein (LDL) 0.84–1.19 mmol L−1 and very-low-density lipoprotein (VLDL) 0.27–0.78 mmol L−1. Values reported here will be useful for evaluating the health status, interpretation and better understanding of various disease signs in sobaity sea bream juveniles.

Spawning, egg development and early ontogenesis in rock cod Patagonotothen ramsayi (Regan, 1913) caught on the Patagonian Shelf and maintained in captivity

Rock cod Patagonotothen ramsayi (Regan, 1913) is one of the most abundant fish of the family Nototheniidae inhabiting the Patagonian Shelf and upper Slope in the southwest Atlantic. Recently, P. ramsayi became an important commercial species around the Falkland Islands with annual catch of 60,000–75,000 t. The present study aimed to reveal previously unknown aspects of reproductive biology of P. ramsayi during the first successful maintenance of adults for more than a year in an aquaculture facility with running seawater. The fish spawned at the end of austral winter. During spawning, males changed their coloration dramatically, occupied artificial shelters on the bottom and showed aggressive territorial behaviour. Egg masses were light-yellow to light-orange irregular spongiform. They were negatively buoyant, but located outside shelters and were ignored by males. Egg diameters varied between 2.1 and 2.3 mm, and the number of eggs per egg mass ranged from 26,800 to 123,400. Embryogenesis lasted 28–32 days. Total lengths of newly hatched larvae ranged from 6.2 to 6.7 mm. The yolk sac feeding period lasted approximately 11 days, during which the larvae showed negative phototaxis. One-month-old larvae attained 8.8–9.0 mm in length. This study confirms that P. ramsayi exhibit the reproductive strategy typical for nototheniid species occupying low-latitude peripheries of their distributional range, characterised by a combination of r-features (small eggs and larvae, high fecundity) and K-features (territorial behaviour and possible nest guarding).

Experimental Grow-Out of the Omani AbaloneHaliotis mariaeWood, 1828, in Land-Based Tanks in Mirbat, Oman

Hatched larvae, juveniles, and adults of the Omani abalone Haliotis mariae were cultivated in land-based tanks with filtered running seawater during 3 experiments: (1) from January 2001 to December 2005, (2) from January 2006 to November 2009, and (3) from January 2009 to December 2011. Larvae and early juveniles were fed daily with diatoms, whereas late juveniles and adults were fed with artificial food and the green algae Ulva fasciata. Shell length and total wet weight from 40–80 randomly selected specimens in various experiments were measured monthly, and sex and gonad maturity stage were defined visually. The water parameters in tanks reflected the ambient condition of the Arabian Sea. The growth pattern of the abalone was very similar in the 3 experimental trials. Larvae and early juveniles have very fast growth rates, reaching an average 53–56 mm and 19–25 g after 1 y. Better results were obtained in the second and third experiments, when at the end of 2 y of rearing, abalone mean length was 67–72 mm and the weight was 46–54 g. At the age 3 y, abalone attained a mean length of 83–85 mm and a weight of 89–93 g. After 6 y, the abalone from the first experiment (2001 to 2005) showed, on average, 88.5 mm and 110.9 g. The length increments were the highest during the first year of the culture, whereas weight increments reached maximum values during the third (second and third trials) and fourth year (first trial) of rearing. After 4 y, abalone growth increments in weight decreased significantly. Males generally but not always have larger increments in length and weight when compared with females. During cultivation, a decrease in abalone weight was sometimes observed that, in most cases, coincided with decrease in water temperature during the southwest monsoon period (June to September). Some abalone sexually matured in tanks after 1 y, and mature males and females occurred almost year-round, with peaks in April to May and November to December. The length at first maturity was found to be 65.2 mm for males and 67.1 mm for females. Growth parameters for a von Bertalanffy function were calculated using data from different experiments. The growth rate coefficient in the first experiment was lower (K = 0.65), but in third experiment it appeared higher (K = 0.80) than in natural conditions from data other authors calculated based on length-frequency distribution analysis, which indicates faster growth rates of abalone in tanks when compared with those in the wild. Results of the trials showed that it is feasible to produce Omani abalone in land-based farms from eggs to commercial size during a 3 4-y cycle.

Acclimation of Red Sea macroalgae to solar radiation: photosynthesis and thallus absorptance

Thallus absorptance, daily courses of maximal quantum yields of chlorophyll fluores- cence of photosystem II (Fv/Fm) and electron transport rates (ETR) were determined in 3 macroalgae (Hypnea spinella, Rhodophyta; Sargassum vulgare, Phaeophyta; and Ulva lactuca, Chlorophyta) collected from a low nutrient supply (LNS) ecosystem (Red Sea, Gulf of Aqaba, Eilat, Israel). In addi- tion, U. lactuca grown previously in high nutrient supply (HNS) fishpond effluents was used to eval- uate the effect of nutrient enrichment on photosynthesis. Short-term (2 d) and mid-term (5 d) effects of both photosynthetically active radiation (PAR) and full solar irradiance (PAB: PAR+UVA+UVB) at 3 solar irradiance treatments (no neutral filters, no NF; 2 neutral filter layers, 2NF; and 4 neutral filter layers, 4NF simulating levels of irradiance at 5, 10 and 20 m depth respectively) were evaluated in algae incubated with running seawater. Significant effects of time (variation throughout the day) and irradiance (number of neutral filters) on both Fv/Fm and ETR were observed. Photoinhibition occurred at noon under the no NF (up to 40% decrease) and 2NF (up to 30% decrease) treatments; however, full recovery in all treatments was reached in the afternoon (dynamic photoinhibition) except in H. spinella. The highest maximum ETR was observed in the no NF treatment despite its strongest photoinhibitory effect. The decrease in Fv/Fm at noon was similar to or higher under the PAB than under the PAR treatment alone, depending on the species. Photoinhibition was lower and the maxi- mum ETR was higher in HNS than in LNS U. lactuca, indicating positive effects of nutrient supply on both photosynthesis and photoprotection. The maximum ETRs exhibited by different algae may be related to their zonation in the field and the resulting energy supply.

Predation of shore crabs ( Carcinus maenas (L.)) and starfish ( Asterias rubens L.) on blue mussel ( Mytilus edulis L.) seed from wild sources and spat collectors

In The Netherlands, several pilot projects are carried out on the use of spat collectors as an additional supply of seed for bottom culture of mussels ( Mytilus edulis). The method proves to be successful in yielding substantial amounts of seed. One of the conditions for successful application of collector seed on bottom plots is a good yield of the seed on bottom plots. Mussel seed of different origin (from wild littoral and sublittoral beds or from collectors) was offered to predators (crabs Carcinus maenas and starfish Asterias rubens) and seed survival was monitored. In addition, the effect of density and size of collector seed on predation was studied. Circular cages containing predators and seed were placed in a basin with running seawater, or suspended from a jetty in a harbour. Two size classes of predators and three size classes of seed were used. Survival was monitored. Consumption of mussel seed by starfish was much lower than by crabs. Maximum observed consumption rates were 23 seed/day/crab and 1 seed/day/starfish. Consumption rates increased significantly with decreasing seed size. Seed larger than 20 mm were consumed at a significantly lower rate. Seed density did not affect survival. Collector seed was not consumed at higher rates than wild littoral or sublittoral seed. In conclusion, collector seed can be a promising additional source of seed for bottom culture of mussels in The Netherlands.

Force production during escape responses by Placopecten magellanicus is a sensitive indicator of handling stress: Comparison with adductor muscle adenylate energy charge and phosphoarginine levels

Scallops are quite vulnerable to handling and transport because they cannot completely close their valves. We examined how handling stress changed force production during escape responses of juvenile giant scallops, Placopecten magellanicus and compared these changes to those of adenylate energy charge (AEC) and phosphoarginine levels in the adductor muscle. We characterised force production 1) after the scallops were transported by boat in pearl nets from the culture site to the sorting area; 2) after the semi-mechanical sorting procedure; 3) after 3 h recuperation in holding tanks supplied with running seawater pumped in from the lagoon and 4) after 24 h recuperation in these tanks. Biochemical measurements were made at the first 3 stages. The patterns of force production during escape responses and muscle biochemistry showed clear parallels. The number and force of phasic contractions was markedly reduced by handling stress (transportation and sorting) but improved with recuperation in the holding tanks. Reliance on tonic contractions increased with handling stress but was reduced by recuperation. Phosphoarginine and adenylate levels in the adductor muscle confirmed that transport and handling were stressful and that 3 h in the holding tank allowed recuperation from this stress. The simplicity of measurements of force production during escape responses suggests this approach could be useful during planning of aquaculture operations. As these tests are non-destructive, they could also be used to monitor the status of scallops.

Cost of transport and optimal swimming speed in farmed and wild European silver eels ( Anguilla anguilla)

A swimming speed of 0.4 meters per second (m s − 1 ) is the minimal speed for European female silver eels to reach the spawning sites in the Sargasso Sea in time. As silver eels cease feeding when they start their oceanic migration, the cost of transport (COT) should be minimised and the swimming speed optimised to attain the highest energetic efficiency. In this study, we have investigated the optimal swimming speed ( U opt) of silver eels since U opt may be higher than the minimal swimming speed and is more likely to resemble the actual cruise speed. A variety of swimming tests were performed to compare endurance swimming between farmed eels and wild eels, both in freshwater and in seawater. The swimming tests were run with 101 silver female eels (60–96 cm, 400–1500 g) in 22 Blazka-type swim tunnels in a climatised room at 18 °C with running freshwater or seawater. Tests were run at 0.5–1.0 m s − 1 with increments of 0.1 m s − 1 , and either 2 h or 12 h intervals. Remarkably, both tests revealed no changes in oxygen consumption ( M˙O 2) and COT over time. U opt values ranged between 0.61 and 0.68 m s − 1 (0.74–1.02 BL s − 1 ) for the different groups and were thus 53–70% higher than the minimal speed. At U opt, the COT was 37–50 mg O 2 kg − 1 km − 1 . These relatively very low values confirm our earlier observations. COT values in seawater were about 20% higher than in freshwater. Assuming that migrating female silver eels cruise at their U opt, they will be able to cover the distance to the Sargasso Sea in 3–4 months, leaving ample time for final maturation and finding mates.

Insights into spawning behavior and development of the european amphioxus (Branchiostoma lanceolatum)

The cephalochordate amphioxus (Branchiostoma sp.) is an important animal model for studying the evolution of chordate developmental mechanisms. Obtaining amphioxus embryos is a key step for these studies. It has been shown that an increase of 3-4 degrees C in water temperature triggers spawning of the European amphioxus (Branchiostoma lanceolatum) in captivity, however, very little is known about the natural spawning behavior of this species in the field. In this work, we have followed the spawning behavior of the European amphioxus during two spawning seasons (2004 and 2005), both in the field and in captivity. We show that animals in the field spawn approximately from mid-May through early July, but depending on the year, they show different patterns of spawning. Thus, even if temperature has a critical role in the induction of the spawning in captivity, it is not the major factor in the field. Moreover, we report some improvements on the methodology for inducing spawning in captivity (e.g. in maintenance, light cycle control and induction of spawning in a laboratory without running sea water system). These studies have important implications for amphioxus animal husbandry and for improving laboratory techniques to develop amphioxus as an experimental animal model.

Size independent selective filtration of ultraplankton by hexactinellid glass sponges

Selective feeding by flagellate and ciliate protists is important in shaping microbial communities in pelagic habitats. While less is known of predation on microbial communities in benthic habitats, the abundance and high filtering capacity of sponges suggests that they are key grazers. We studied the feeding preferences of two of the most common glass sponges of North-East Pacific fjords, Rhabdocalyptus dawsoni and Aphrocallistes vastus. Sponges were maintained in large darkened tanks supplied with running seawater from the nearby fjord. The water inhaled and exhaled by the sponges was simultaneously sampled and analyzed using a flow cytometer. Both sponges showed a similar (but not identical) feeding pattern, efficiently removing up to 99 % of the most abundant bacterial cells, whereas clays, silt, and 'debris' particles were expelled into the exhaled water. Filtration efficiencies were maximal for the relatively large and rare eukaryotic algae (3 to 5 μm, 86±9%) and for small non-photosynthetic bacteria (<0.4 pm, 89 ± 10%), while intermediate sized non-photosynthetic bacteria characterized by higher nucleic acid content were efficiently removed in February (92 ± 3%) when overall plankton concentration was low, but not in July (28 ± 16%). The intermediate sized photosynthetic prokaryote Synechococcus (1.1 to 1.5 pm) was also less preferred. Detailed analysis of the ultrastructure of the glass sponge filtration apparatus argues against possible 'by-pass' routes. We suggest that selective filtration involves individual processing, recognition, sorting, and transport of each particle through the sponges' syncytial tissue. Selective grazing by glass sponges, like their pelagic protozoan counterparts, could be an important mechanism shaping microbial communities in the detrital food web of North-East Pacific fjords.

Linking Adhesive and Structural Proteins in the Attachment Plaque of Mytilus californianus

The byssal attachment of California mussels Mytilus californianus provides secure adhesion in the presence of moisture, a feat that still eludes most synthetic polymers. Matrix-assisted laser desorption ionization mass spectrometry was used to probe the footprints of byssal attachment plaques on glass cover slips for adhesive proteins. Besides the abundant mcfp-3 protein family (Zhao, H., Robertson, N. B., Jewhurst, S. A., and Waite, J. H. (2006) J. Biol. Chem. 281, 11090-11096), two new proteins, mcfp-5 and mcfp-6, with masses of 8.9 kDa and 11.6 kDa, respectively, were identified in footprints, partially characterized and completely sequenced from a cDNA library. mcfp-5 resembles mcfp-3 in its basic pI and abundant 3,4-dihydroxyphenyl-L-alanine (Dopa; 30 mol %), but is distinct in two respects: it is more homogeneous in primary sequence and is polyphosphorylated. mcfp-6 is basic and contains a small amount of Dopa (<5 mol %). In contrast to mcfp-3 and -5, tyrosine prevails at 20 mol %, and cysteine is present at 11 mol %, one-third of which remains thiolate. Given the oxidative instability of Dopa and cysteine at pH 8.2 (seawater), we tested the hypothesis that thiols serve to scavenge dopaquinones by adduct formation. Plaque footprints were hydrolyzed and screened for cysteine dopaquinone adducts using phenylboronate affinity chromatography. 5-S-Cysteinyldopa was detected at nearly 1 mol %. The results suggest that mcfp-6 may provide a cohesive link between the surface-coupling Dopa-rich proteins and the bulk of the plaque proteins.

First record of planktonic egg masses of the diamond squid, Thysanoteuthis rhombus Troschel, in the Sea of Japan

This paper provides the first evidence that Thysanoteuthis rhombus spawns in the Sea of Japan. Five planktonic egg masses were collected in the southern Sea of Japan during 29 October to 24 November 2004 and transported to onshore laboratories for observation. Part of each egg mass was reared in indoor, aerated tanks supplied with filtered running seawater. The egg masses (ca. 60-120 cm in total length and 13-15 cm in diameter) were cylindrical with rounded ends and consisted of a resilient, transparent gelatinous core with a pair of egg rows forming spiral loops around the core. The embryos had dome-shaped mantles covered with many chromatophores and slowly rotated inside the spherical egg capsules. Hatching was observed in all the egg masses 3-10 days after collection. Morphological characteristics of the egg masses, eggs and embryos, especially the large number of chromatophores present in the early embryonic stages, agreed with the descriptions in previous studies. Near the collections sites, surface water tem- perature and salinity ranged 18-22 °C and 33.3-33.7, respectively, both of which were lower than the optimum conditions for T. rhom- bus spawning. The early embryonic stages of the egg masses at collection such as cleavage and slow currents at the sea surface suggest the egg masses were spawned near the collection sites. Increased abundance of T. rhombus in the Sea of Japan and increased sampling efforts were proposed as two possible causes for the egg-mass discoveries.

Phytotoxicity of Photosystem II (PSII) herbicides to coral

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 261:149-159 (2003) - doi:10.3354/meps261149 Phytotoxicity of Photosystem II (PSII) herbicides to coral Ross J. Jones*, Ailsa P. Kerswell Centre for Marine Studies, The University of Queensland, St Lucia Campus, Brisbane, Queensland 4072, Australia *Email: rjones@uq.edu.au ABSTRACT: Recent reports of contamination of the Great Barrier Reef Marine Park by herbicides used in antifouling paints and in agriculture have caused concern over the possible effects on corals in nearshore areas. Pulse-Amplitude Modulated (PAM) chlorophyll fluorescence techniques were used to examine changes in the maximum effective quantum yield (ΔF/Fm¹) of symbiotic dinoflagellates within the host tissues (in hospite) of the coral Seriatopora hystrix exposed to a number of Photosystem II (PSII) inhibiting herbicides in short-term toxicity tests. The concentration of herbicide required to reduce ΔF/Fm¹ by 50% (median effective concentration [EC50]) differed by over 2 orders of magnitude: Irgarol 1051 (0.7 µg l-1) > ametryn (1.7 µg l-1) > diuron (2.3 µg l-1) > hexazinone (8.8 µg l-1) > atrazine (45 µg l-1) > simazine (150 µg l-1) > tebuthiuron (175 µg l-1) > ionynil (>1 mg l-1). Similar absolute and relative toxicities were observed with colonies of the coral Acropora formosa (Irgarol 1051 EC50: 1.3 µg l-1, diuron EC50: 2.8 µg l-1). Time-course experiments indicated that ΔF/Fm¹ was rapidly reduced (i.e. within minutes) in S. hystrix exposed to Irgarol 1051 and diuron. On return to fresh running seawater, ΔF/Fm¹ recovered quickly in diuron-exposed corals (i.e. in minutes to hours), but slowly in corals exposed to Irgarol 1051 (i.e. hours to days). Time-course experiments indicated that the effects of diuron (3 µg l-1) on S. hystrix were inversely related to temperature over the range 20 to 30°C, although initially the effects were less at the lower temperatures. Repeated exposure to pulses of Irgarol 1051 (daily 2 h exposure to 30 µg l-1 over 4 d) resulted in a 30% decrease in the density of symbiotic dinoflagellates in the tissues of S. hystrix. KEY WORDS: Coral · Coral bleaching · Symbiotic dinoflagellate · Irgarol 1051 · Diuron · Herbicide · Chlorophyll fluorescence Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 261. Online publication date: October 17, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.