Distribution of lipolytic,proteolytic, and amylolytic marine bacteria between the lipid film and the subsurface water

The biochemical activity of marine bacteria adhering to the lipid film at the airwater interface was compared to that of bacteria inhabiting the subsurface water. The bacteria were isolated from the two levels at 7 stations, all located along Brofjorden on the Swedish West Coast. The isolates were tested for their ability to attack lipids, proteins, and carbohydrates. A higher percentage of active isolates was found in samples from the subsurface water than from the surface film. The accumulation of marine bacteria at the air-water interface is not due to their biochemical activity.     

Changes in intestinal absorption and renal excretion of water during adaptation to sea-water in the Japanese eel

The rate of sea-water ingestion in Japanese cultured eels, Anguilla japonica, adapted to sea-water for one week, was 89±9.5 ml/kg/day; approximately 75% of the ingested water was absorbed by the intestine. Similar rates of ingestion and absorption of water were also found with sea-water-adapted rainbow trout, Salmo gairdnerii, and two species of marine teleosts, Stephanolepis cirrhifer and Goniistius zonatus. When cultured eels were transferred from freshwater to sea-water the amount of ingested and absorbed water inoreased gradually to a maximum on the 5^th day and then decreased to a constant level. The urine flow and glomerular filtration rate were found to be high in freshwater cultured eels, and both reduced markedly within 6 h after transferring the eel to sea-water. The reabsorption of water by the renal tubules was very small in both the freshwater and sea-water-adapted (6 h) eels. On the other hand, in the eels adapted to sea-water for 10 days the rate of urine flow was also very slight but the glomerular filtration rate recovered to that of the freshwater eels. Thus, water reabsorption by the tubules increased to a large degree. The results seem to indicate the existence of two distinct phases in the renal function during sea-water adaptation of cultured eels.     

Biodegradation kinetics of cymoxanil in aquatic system

A potential method to detoxify pesticides in aquatic system is using bioremediation. In this study, four microorganisms (Pseudomonas sp (EB11), Streptomyces sp. (EB12), Aspergillus niger (EB13) and Trichoderma viride (EB14) were isolated from cucumber leaves previously treated with cymoxanil using enrichment technique. These strains were evaluated for their potential to detoxify cymoxanil in aquatic system at the concentration level of 5×10^?4M. The effect of pH and temperature on the growth ability of the tested strains was also investigated by measuring the intracellular protein and mycelia dry weight for bacterial and fungal strains, respectively. Moreover, the remaining toxicity of cymoxanil after 28 days of incubation with tested strains was evaluated to confirm the complete removal of any toxic materials (cymoxanil and its metabolites). The results showed that the optimum pH for the growth of cymoxanil degrading strains (bacteria and fungi) was 7. A temperature of 30°C appears to be the optimum for the growth of either fungal or bacterial strains. Pseudomonas sp. (EB11) was the most effective strain in cymoxanil degradation followed Streptomyces sp (EB12), Trichoderma viride (EB14) and Aspergillus niger (EB13), with half-lives of 4.33, 9.5, 17.3 and 24.7 days, respectively. The degradation of cymoxanil by bacterial strains was much faster than fungal one. There is no remaining toxicity of cymoxanil detected in aqueous media previously treated with Pseudomonas sp. (EB11) for 28 days. The results suggest that bioremediation by Pseudomonas sp. (EB11) are promising for the detoxification of cymoxanil in aqueous media.     

Antifungal activity of volatile metabolites emitted by mycelial cultures of saprophytic fungi

The antifungal activity of molecular identified Chilean saprobiontic fungi, Trichoderma viride, Schizophyllum commune and Trametes versicolor, on the fungal plant pathogens Botrytis cinerea and Fusarium oxysporum, and the saprotrophic mould Mucor miehei was investigated using two types of inhibition bioassay: (1) bi-compartmented Petri dishes and (2) two Erlenmeyer flasks connected by their upper parts. The chemical composition of volatile organic compounds (VOCs) released by saprobiontic fungi was also investigated using headspace solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC-MS) analysis. Of the saprobiontic fungi evaluated, one isolate of S. commune showed the highest inhibitory activity against B. cinerea and M. miehei, 86.0±5.4 and 99.5±0.5% respectively. The volatile profiles of fungal isolates were shown to contain a different class of compounds. The major components in the headspace of mycelial cultures were 6-pentyl-α -pyrone (T. viride), ethanol and β -bisabolol (S. commune), and a sesquiterpene alcohol (Tr. versicolor). This is the first study reported on the release of VOCs by Chilean native fungi and their antifungal activity wrt. plant pathogenic fungi.     

Contrasting population structures in two sympatric fishes in the Baltic Sea basin

Detailed multispecies studies on the patterns of genetic variability and differentiation in marine environments are still rare. Using mitochondrial and nuclear genetic markers, we compared genetic variability and population structuring of threespine (Gasterosteus aculeatus) and ninespine (Pungitius pungitius) sticklebacks from the same eleven marine and six freshwater locations within the Baltic Sea basin. Analyses of both marker types revealed a significantly lower degree of genetic structuring in both marine and freshwater populations of threespine than those ninespine sticklebacks. Isolation-by-distance (IBD) was detected across the marine populations in both species, suggesting spatially limited gene flow. However, the levels of genetic diversity and differentiation across the localities were uncorrelated between the two species in both marine and freshwater environments. Accordingly, estimates of effective population sizes were larger and migration rates were higher for three- than for ninespine sticklebacks. Hence, ninespine stickleback populations from the Baltic Sea basin appear to be subject to stronger genetic drift than sympatric threespine sticklebacks, and the proximate reason for this difference is likely to be found from autecological differences between the two species. In accordance with the earlier studies, genetic variability was higher and the degree of genetic differentiation was lower in marine than in freshwater populations in both species.     

The enumeration and characterization of bacteria and fungi associated with marine wood-boring isopods,and the ability of these microorganisms to digest cellulose and wood

Bacteria and fungi associated with the marine wood-boring isopods Limnoria lignorum and Sphaeroma serratum, and with their wood burrows and seawater were investigated. Plate counts using nutrient agar and Czapex Dox agar media in natural and in artificial seawater were used. The diversity and number of bacteria associated with the two isopods were much higher than those associated with wood or seawater, whereas the opposite was true for fungi. The hydrolytic activity of the predominant genera on carboxymethylcellulose and on different types of wood was investigated. The magnitude of fungal cellulase activity exceeded that of bacteria. Activities of bacterial extracellulases exceeded those of intracellulases, while the opposite was observed for fungi. Cellulolytic activity of the predominant isolates biodegraded labkh, peach, white oak and mahogany in decreasing order of activity. Evidence provided by the cellulolytic activities, detected in woodcontaining cultures, suggests that the predominant micro-organisms isolated may play an important role in the woodboring process. Specimens used in the present study were collected from Port Fouad at Port Said Harbour, Egypt.     

Changes in water and ion transport in isolated intestines of the eel during salt adaptation and migration

When Japanese cultured eels, Anguilla japonica, were transferred from freshwater to sea-water, their body weight decreased by 15% on the second day and then recovered gradually to the original weight within a week. Serum sodium content increased by 58% on the second day, and thereafter decreased to a constant level. Isolated intestines from these eels were bathed on both sides, mucosal and serosal, by identical Ringer solution. The water and sodium transort was very active from mucosa to serosa in such isolated intestines of sea-water-adapted eels. This active movement was particularly dominant during the week after transferring the eel to seawater, and a peak was reached on the fifth day. The molar ratio of water to sodium in the fluid moving across the intestinal wall was higher in sea-water-adapted eels than in freshwater eels. The isolated intestines taken from silver eels during their catadromous migration, but still in the river, showed a larger amount of water transport and a higher molar ratio of water to sodium than intestines from yellow sedentary eels. These adaptive properties are a prerequisite for the marine life of the eel.     

Antimicrobial activities of extracts from tropical Atlantic marine plants against marine pathogens and saprophytes

Studies investigating disease resistance in marine plants have indicated that secondary metabolites may have important defensive functions against harmful marine microorganisms. The goal of this study was to systematically screen extracts from marine plants for antimicrobial effects against marine pathogens and saprophytes. Lipophilic and hydrophilic extracts from species of 49 marine algae and 3 seagrasses collected in the tropical Atlantic were screened for antimicrobial activity against five ecologically relevant marine microorganisms from three separate kingdoms. These assay microbes consisted of the pathogenic fungus Lindra thalassiae, the saprophytic fungus Dendryphiella salina, the saprophytic stramenopiles, Halophytophthora spinosa and Schizochytrium aggregatum, and the pathogenic bacterium Pseudoaltermonas bacteriolytica. Overall, 90% of all species surveyed yielded extracts that were active against one or more, and 77% yielded extracts that were active against two or more assay microorganisms. Broad-spectrum activity against three or four assay microorganisms was observed in the extracts from 48 and 27% of all species, respectively. The green algae Halimeda copiosa and Penicillus capitatus (Chlorophyta) were the only species to yield extracts active against all assay microorganisms. Among all assay microorganisms, both fungi were the most resistant to the extracts tested, with less than 21% of all extracts inhibiting the growth of either L. thalassiae or D. salina. In contrast, over half of all lipophylic extracts were active against the stramenopiles H. spinosa and S. aggregatum, and the bacterium P. bacteriolytica. Growth sensitivity to hydrophilic extracts varied considerably between individual assay microorganisms. While 48% of all hydrophilic extracts were active against H. spinosa, 27% were active against P. bacteriolytica, and only 14% were active against S. aggregatum. Overall, more lipophilic extracts inhibited microbial growth than hydrophilic extracts. The variability observed in the antimicrobial effects of individual extracts against each assay microorganism reflects the importance of choosing appropriate test microbes in assays from which ecologically relevant information is sought. Results from this survey demonstrate that antimicrobial activities are prevalent among extracts from marine algae and seagrasses, suggesting that antimicrobial chemical defenses are widespread among marine plants.     

Occurrence of marine resident tropical eel Anguilla bicolor bicolor in Indonesia

In order to understand the migratory history and habitat use of the tropical anguillid eels Anguilla celebesensis, A. marmorata, and A. bicolor bicolor, the otolith strontium (Sr) and calcium (Ca) concentrations were examined for eels collected in Indonesian waters. In A. bicolor bicolor collected in a lagoon, the change in Sr:Ca ratios outside the high Sr:Ca core generally indicated two patterns of habitat residence: (1) constant living in either brackish or sea waters with no freshwater life (25%) and (2) habitat shifts from fresh water to brackish or sea waters (75%). No A. bicolor bicolor had a general life history as a freshwater resident. A. celebesensis and A. marmorata from the uppermost freshwater lake showed freshwater life history patterns. The wide range of otolith Sr:Ca ratios in A. bicolor bicolor indicated that the habitat use of this tropical eel was facultative among fresh, brackish, and marine waters during the growth phase after recruitment to coastal areas similar to that for temperate eels. Thus, the migration of anguillid eels into fresh water is clearly not an obligatory.     

Mycoremediation of diclofenac using Mucor hiemalis

Diclofenac (DCF) is a pharmaceutical drug widely found in the aquatic environment, where it represents a persistent, anthropogenic hazard to all biota. Owing to the reported inefficiency of water treatment strategies to remove pharmaceuticals, the present study aimed to investigate the ability of the aquatic fungus Mucor hiemalis to take up and accumulate DCF. Cultures of M. hiemalis were exposed to varying concentrations of DCF (10, 25 and 50 µg/L) over a period of 144 h. In the presence of M. hiemalis, DCF concentrations in the media decreased by 95% within 24 h. This early removal was most likely due to extracellular metabolism of DCF, as low proportions of the pharmaceutical were found in the mycelium of the fungus, thereby excluding bioaccumulation as the main mode of removal. However, adsorption of DCF onto the surface of the M. hiemalis pellets cannot be excluded. Our study provides the first report of DCF remediation using M. hiemalis and is the first successful step towards a feasible and inexpensive bioremediation technique for DCF.     

Genetic structure in lagoons: the effects of habitat discontinuity and low dispersal ability on populations of <Emphasis Type="Italic">Atherina boyeri</Emphasis>

Atherina boyeri is a common inhabitant of the Mediterranean brackish and coastal waters. Several recent studies proposed the recognition of three distinct forms/species (one lagoon/freshwater and two marine) within an A. boyeri complex. In this study, we used 10 newly available microsatellite loci to better define the genetic structure of the lagoon form. A total of 428 fishes from 11 lagoons along the Italian and Albanian coasts and three Italian lakes were analyzed. A pronounced genetic spatial structure was confirmed for all considered geographic scales (near, medium and broad). A restricted gene flow was detected, suggesting reduced population connectivity. The comparison of present data and previous studies, based on mtDNA and RAPD markers, allowed a preliminary identification of the roles of recent factors (gene flow, habitat discontinuity and water currents) and past events (e.g., Pleistocene glaciations) in shaping the pattern of genetic differentiation.     

Copépodes planctoniques du lagon de Nouvelle-Calédonie: facteurs écologiques et associations d'espèces

In the southwestern part of the lagoon of New Caledonia (South Pacific Ocean), a plankton sampling programme was conducted from February 1978 to April 1979. During 11 cruises, 5 stations in the open sea and various bays were sampled at approximately monthly intervals. A transect of 3 stations (mid lagoon, near-reef and barrier-reef channel) visited each fortnight, completed the sampling programme. The copepods collected were identified to the specific level, counted and the 52 most abundant species analysed for seasonal and regional variations. Cruise and transect data, dealt with separately, were analysed as follows: (a) Correspondence analyses (reciprocal averaging) of qualitative and quantitative copepod counts were made; these revealed the relationships between species and between samples by means of factorial design. After computation of factorial axes, the barycentres of different sets of samples were projected as reference points (zero weight) in the factorial space; these reference points, characterizing different stations and sampling times, facilitate ecological interpretation. (b) Species partition was achieved by two successive methods: non-hierarchical, followed by hierarchical classification. Between-species distance was computed from their co-ordinates on the factorial axis. (c) The clusters of species obtained were plotted in the factorial planes to assess ecological preference. Then, clusters from cruise and transect data sets were compared to improve the copepod classification. The main ecological factors appear to be (i) spatial patterns, (ii) seasonal temperature cycle, (iii) changes in wind force and direction. Different populations inhabit the open sea, near-reef, mid-lagoon, shallow and deep-bay waters. Acartia australis outnumbers all other species in the reef vicinity. A. amboinensis is the most abundant in the deep, fjord-like bay. Canthocalanus pauper, Paracalanus parvus, Bestiola sp., Centropages orsinii, A. bispinosa are characteristic of shallow bays. In the factorial structure produced by correspondence analysis, certain seasonal barycentres appear close to some station barycentres: summer close to mid-lagoon, winter close to open sea, and spring close to near-reef barycentres, respectively. This may be explained by the seasonal dynamics of the lagoon water. After the heavy summer rainfalls, freshwater runoff carries midlagoon plankton towards the open sea; conversely, during the winter westerly gales, oceanic species enter the lagoon through the barrier-reef channel or above the reef with the swell breakers. In October, the surface-layer current induced by the strong trade wind carries large swarms of A. australis out to the open sea. Finally, the variations of plankton populations and biomass in the lagoon seem to be governed by the direction of water flow across the reef channels. Enrichment factors are terrestrial sediment wash-out after rainfall and, probably, trade wind-induced upwelling. Therefore, the more or less steady state of the lagoon's plankton biomass may result from the fact that enrichment factors are also exportation factors. Reciprocally, the entry of plankton-poor oceanic water cannot increase the plankton biomass in the lagoon.     

Growth of Uronema marinum in chemically defined medium

A strain of the marine hymenostome ciliate Uronema marinum was isolated in axenic culture. This strain, designated PW2, was cultivated in a chemically defined medium containing 17 amino acids, 4 nucleotides, 5 fatty acids, stigmasterol, 8 growth factors and an artificial sea water. Increased populations were observed when either phosphatidylinositol or Tween 80 were included in the medium. The vitamins thiamine, riboflavin, pyridoxal, nicotinamide, folic acid and pantothenate were required by U. marinum PW2. No requirement could be demonstrated for exogenous thioctic acid or biotin, although growth was diminished in their absence. The amino acid and nucleotide requirements were found to be higher than the levels reported for other ciliates. This strain was found to be euryhaline, with maximum growth observed in media of specific gravity 1.007, corresponding to approximately 25% sea water. Although no requirement could be demonstrated for Fe, Zn, Mn or Cu, high levels of these metals were observed to be toxic. Growth was observed over a pH range of 6.6 to 8.3, with an optimum observed near 7.3.     

Water balance systems of Rangia cuneata: ionic and amino acid regulation in changing salinities

In order to study the interaction of the extracellular and intracellular osmoregulatory systems of the bivalve Rangia cuneata, we have measured blood osmotic and ionic concentrations together with intracellular free amino acid concentrations and total tissue water under identical salinity conditions. Like freshwater bivalves, the blood of R. cuneata is maintained hyperosmotic (50 mOsm) to the environment in salinities below 110 mosm by the regulation of Na⁺, Cl^-, K⁺ and Ca²⁺ concentrations. On the other hand in company with marine bivalves, R. cuneata also regulates intracellular free amino acids (FAA) as a mechanism to control cellular volume during osmotic stress over the entire non-lethal salinity range (3 to 620 mOsm). Alanine is the predominant intracellular osmotic effector. Thus, by utilizing the osmoregulatory mechanisms of both marine and freshwater bivalves, R. cuneata is able to tolerate salinities ranging from freshwater to 25 ppt and to traverse the faunal salinity boundary, known as the horohalinicum (5 to 8 ppt), controlling cell volume throughout.Please address requests for reprints to Dr. S. K. Pierce     

Offshore–inshore and vertical distributional patterns of heteropod mollusks off leeward Oahu, Hawaii

Replicated zooplankton tows were taken during day and night periods at neritic (1 nmi offshore) and oceanic (5 and 15 nmi offshore) stations off the leeward side of Oahu, Hawaii during fall (September) and spring (April). Plankton samples were obtained with a 1-m² MOCNESS net system towed obliquely through seven depth strata to 80 m (neritic station) and eight depth strata to 200 m (oceanic stations). Five more species were collected in April (17) than in September (12). During both months the number of species decreased from the 15 to the 1 nmi stations; from 11 to 9 in September and 15 to 11 in April. Species diversity, as measured by species accumulation (rarefaction) curves, was higher at the 15 than the 1 nmi stations during both months. Total nighttime water column density in April was about double that in September. In September, the density decreased sevenfold from the 15 to 1 nmi stations, but in April densities were comparable among the three stations; mainly as a result of the shoreward increase in density of Atlanta plana. The most abundant species in both months were A. plana, A. lesueuri, A. inflata, A. peroni, and Protatlanta souleyeti, which in combination accounted for 93% (September) and 91% (April) of the total nighttime water column densities. The vertical ranges of six species were limited to the upper 100 m, and nocturnal migration was suggested for two (A. helicinoides during both months and A. turriculata in April). The ranges of the remaining 11 species extended to 160 or 200 m, and among them nocturnal migration was suggested for five (A. plana, A. meteori and Pterotrachea hippocampus during both months, and A. peroni and Protatlanta soueleyti in April).     

Long-term changes in the benthic community on the coastal shelf of Palos Verdes,Southern California

Between 1972 and 1982, both wastewater discharge and natural perturbations played important roles in directing marine benthic community structure on the Palos Verdes Shelf in Southern California, USA. Community succession was traced along a gradient of eleven 60 m-depth stations extending from the submarine outfalls. Spatial and temporal biological patterns were identified via direct gradient, clustering and principal-coordinates analyses. Species associations which occupied sites distant from the outfalls in the early 1970s gradually became established closer to the diffusers during the decade. The areal extent of outfall impacts shrank, reflecting both improvements in effluent quality and co-occurring beneficial natural events, specifically the short-term settlement of large numbers of the echiuran Listriolobus pelodes.     

Culturable actinobacteria isolated from marine sponge <Emphasis Type="Italic">Iotrochota</Emphasis> sp.

The study describes the diversity of actinobacteria isolated from the marine sponge Iotrochota sp. collected in the South China Sea. Species and natural product diversity of isolates were analyzed, including screening for genes encoding polyketide synthases (PKS) and nonribosomal peptide synthetase (NRPS), and 16S rRNA gene restriction fragment length polymorphism (RFLP). PKS and NRPS sequences were detected in more than half of the isolates and the different “PKS-I–PKS-II–NRPS” combinations in different isolates belonging to the same species indicated a potential natural product diversity and divergent genetic evolution. The phylogenetic analysis based on 16S rRNA gene sequencing showed that the isolates belonged to genera Streptomyces, Cellulosimicrobium, and Nocardiopsis. The majority of the strains tested belonged to the genus Streptomyces and one of them may be a new species. To our knowledge, this is the first report of a bacterium classified as Cellulosimicrobium sp. isolated from a marine sponge. Key Laboratory of Marine Bio-recourses Sustainable Utilization (LMB-CAS), Guangdong Key Laboratory of Marine Materia Medica (LMMM-GD), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, People’s Republic of China.     

Isolation and characterization of a marine bacteriophage

A bacteriophage active against a marine Aeromonas sp. was isolated from surface sediments of the North Pacific Ocean at 825 m depth. The sensitive Aeromonas sp. grew between 0° and 33°C but plaques were formed only between 0° and 23°C with a maximum zone of lysis at 5° to 12°C. The phage was rapidly inactivated at temperatures above 45°C. The characteristic plaque formation occurred only on media made with sea-water but some lysis was obtained in distilled water media supplemented with 0.085 M NaCl and 0.05 M MgCl₂. Phage replication occurred in cultures of Aeromonas sp. growing under applied hydrostatic pressures of up to 200 atmospheres. Electron microscopy revealed that the phage has an hexagonal head 530 Å in diameter, a thin tail 1200 Å in length and a terminal base plate 400 Å in diameter.     

Physiological basis of the species abundance-salinity relationship in molluscs: A speculation

The relationship between the osmotic pressures of the blood and the ambient medium was determined for 4 species of bivalve molluscs whose habitats represent distinct salinity regimes within the range from fresh to full seawater. These organisms included 3 corbiculids: Corbicula manilensis (freshwater); Polymesoda caroliniana (brackish-water); Pseudocyrena floridana (marine) and 1 unionid: Elliptio lanceolata. On the basis of the data and similar measurements from the literature, we have placed the molluscs into 5 categories: marine stenohaline, marine euryhaline, oligohaline, fresh-water euryhaline and freshwater stenohaline. Marine stenohaline and euryhaline species are osmoconformers. They differ only in the size of the free amino acid pool available for intracellular volume regulation, and thus in the range of salinities that they tolerate. Oligohaline species tolerate salinities from seawater down to freshwater; they not only possess a large capacity for volume regulation, but can also osmoregulate below 3 S. Freshwater species also osmoregulate below 3 S, but they are usually limited to salinities below 2. Presumably, in evolving from the marine to the freshwater habit, they have lost the ability to volume-regulate in response to hyperosmotic stress. We propose that the varying physiological characteristics underlie the well-known relationship that species abundance declines from both freshwater and full seawater to a minimum between 3 and 5 S. We have related this species minimum to physical-chemical discontinuities in the ionic composition of seawater which are, again, reflected in the physiological mechanisms of the molluscs.Contribution No. 50 from the Tallahassee, Sopchoppy and Gulf Coast Marine Biological Association.     

Fine-scale distribution of larval fishes: patterns and processes adjacent to coral reefs in Kaneohe Bay,Hawaii

Plankton samples were taken from January to June 1987 in Kaneohe Bay, Oahu, Hawaiian Islands, with a free-fall plankton net, to investigate the fine-scale distribution of larval fishes around coral reefs. Daytime samples indicated that the postflexion larvae of two gobiids (Psilogobius mainlandi and an unidentified species) were significantly more abundant at stations immediately adjacent to reefs (near-reef) than at stations in open water off the reef (off-reef). These postflexion gobiid larvae appeared to be capable of resisting advection and dispersal while remaining in the water column near suitable adult habitats. The larvae of Foa brachygramma (Apogonidae) and Encrasicholina purpurea (Engraulidae) were significantly more abundant at off-reef stations than at near-reef stations. Nighttime samples indicated that the gobiid larvae depend on visual cues to remain near the reef. The horizontal distributions of F. brachygramma and E. purpurea larvae appeared to be related to their vertical positioning. These data suggest that typical ichthyoplankton surveys which do not sample close to adult fish habitats would greatly underestimate the abundances of larvae such as the gobiids.