Zebra Mussel Antifouling Activity of the Marine Natural Product Aaptamine and Analogs

Several aaptamine derivatives were selected as potential zebra mussel (Dreissena polymorpha) antifoulants because of the noteworthy absence of fouling observed on Aaptos sponges. Sponges of the genus Aaptos collected in Manado, Indonesia consistently produce aaptamine-type alkaloids. To date, aaptamine and its derivatives have not been carefully evaluated for their antifoulant properties. Structure–activity relationship studies were conducted using several aaptamine derivatives in a zebra mussel antifouling assay. From these data, three analogs have shown significant antifouling activity against zebra mussel attachment. Aaptamine, isoaaptamine, and the demethylated aaptamine compounds used in the zebra mussel assay produced EC₅₀ values of 24.2, 11.6, and 18.6 μM, respectively. In addition, neither aaptamine nor isoaaptamine produced a phytotoxic response (as high as 300 μM) toward a nontarget organism, Lemna pausicostata, in a 7-day exposure. The use of these aaptamine derivatives from Aaptos sp. as potential environmentally benign antifouling alternatives to metal-based paints and preservatives is significant, not only as a possible control of fouling organisms, but also to highlight the ecological importance of these and similar biochemical defenses.     

Biofilms and biodiversity: an interactive exploration of aquatic microbial biotechnology and ecology

The study of biofilms provides a unique educational opportunity to examine ecosystems, biodiversity and applications of environmental biotechnology. There are many variables that could be studied for measuring the interactions between bacterial biofilms and invertebrate biodiversity as a method for assessing the health of aquatic ecosystems. These interactions also lend themselves to an easily replicated model system which can be used to reach a wide audience with an educational opportunity for students as well as a professional development opportunity for teachers. At the foundation of the research are invaluable basic microbiology skills: strain collection, isolation, cultivation and characterization. Through the additional process of characterizing, identifying and enumerating invertebrate organisms that attach to bacterial biofilms in aquatic ecosystems, there evolved a multidisciplinary class laboratory activity that has found broad application. This activity is captivating not only to undergraduate microbiology students but to middle and high school students and their teachers. The demand for information about the activity has led to the development of a truly interactive web-based lesson, which in turn has resulted in additional inquiries and further refinement of the lesson as an undergraduate independent research course. Both of these are freely accessible on the web, with growing international participation and data exchange. Journal of Industrial Microbiology & Biotechnology (2000) 24, 334–338. Received 19 April 1999/ Accepted in revised form 17 February 2000     

Legal Traditions,Environmental Awareness,and a Modern Industry: Comparative Legal Analysis and Marine Aquaculture

In the interests of increasing fish production globally, alleviating global poverty, and income generation, marine aquaculture has seen worldwide expansion over the past few decades. However, this expansion has been matched by growing concerns over its environmental impacts. This article utilizes comparative legal analysis to explore the legal systems of governance for the environmental performance of marine aquaculture in four case study countries. Two are members of the European Community (Scotland, as part of the United Kingdom, and Greece), one is a recent accession country (Slovenia), and the fourth is closely linked to the European Community albeit geographically and legally disparate (Israel).     

Mini-review: Impact and dynamics of surface fouling by solitary and compound ascidians

Globally, ascidians are a significant contributor to benthic marine fouling communities, but have remained poorly studied in this context. In some cases, such as in shellfish and finfish aquaculture, ascidians are the most problematic of all fouling organisms. The disproportionate impact of ascidian fouling in some specific geographic locations has been related directly to anthropogenic translocation of these organisms around the globe. In the case of ascidians, therefore, the economic issue of biofouling and the ecological ramifications of invasion are inextricably linked. This mini-review briefly discusses the introduction of non-native ascidians to areas where they have subsequently proven to be a significant fouling pest. The elements of ascidian reproductive ecology that support their aggressive fouling character are discussed and the scant information pertaining to their adhesion and adhesives is presented. Finally, strategies for mitigating ascidian fouling are examined. It is suggested that sufficient working knowledge currently exists to support the inclusion of one or more common ascidian species as ‘standard’ test organisms used for evaluation of novel fouling-resistant surfaces.     

Colonization outwith the colon: plants as an alternative environmental reservoir for human pathogenic enterobacteria

Members of the Enterobacteriaceae have the capacity to adapt to a wide variety of environments and can be isolated from a range of host species across biological kingdoms. Bacteria that are pathogenic to animals, in particular humans, are increasingly found to be transmitted through the food chain by fruits and vegetables. Rather than simply contaminating plant surfaces, there is a growing body of evidence to show that these bacteria actively interact with plants and can colonize them as alternative hosts. This review draws together evidence from studies that investigate proven and potential mechanisms involved in colonization of plants by human pathogenic enterobacteria.     

Pacific Coral-reef Fishes: The Implications of Behaviour and Ecology of Larvae for Biodiversity and Conservation, and a Reassessment of the Open Population Paradigm

The two-phase life history of most marine fishes and invertebrates has enormous implications for dispersal, population connectivity, and resource management. Pelagic dispersal larvae of marine animals traditionally thought to ensure that populations are widespread, that chances of local extinction are low, and that marine protected areas (MPA) can easily function to replenish both their own populations and those of unprotected areas. Traditionally, dispersal is considered to depend primarily on two variables: pelagic larva duration and far-field currents. These conclusions arise from the open population paradigm and are usually accompanied by a simplifying assumption: larvae are distributed passively by far-field currents. Unfortunately, they ignore the complex reality of circulation and hydrological connectivity of reefs, and do not consider newly-demonstrated behavioural capabilities of coral-reef fish larvae. Far-field circulation varies with depth and often excludes water bodies where propagules are released, and this has important implications for predicting trajectories of even passive larvae. However, larvae are not passive: late-stage larvae of coral-reef fishes can swim faster than currents for long periods, can probably detect reefs at some distance, and can actively find them. This behaviour is flexible, which greatly complicates modelling of larval fish trajectories. Populations at ecological (as opposed to evolutionary) scales are probably less open and more subdivided than previously assumed. All this means that dispersal predictions based solely on far-field water circulation are probably wrong. An emerging view of larval-fish dispersal is articulated that takes these new data and perspectives into account. This emerging view shows that re-evaluation of traditional views in several areas is required, including the contribution of larval-fish biology and dispersal to biodiversity patterns, the way reef fishes are managed, and the way in which MPA are thought to operate. At evolutionary and zoogeographic scales, reef-fish populations are best considered to be open.     

Dynamic surface deformation of silicone elastomers for management of marine biofouling: laboratory and field studies using pneumatic actuation

Many strategies have been developed to improve the fouling release (FR) performance of silicone coatings. However, biofilms inevitably build on these surfaces over time. Previous studies have shown that intentional deformation of silicone elastomers can be employed to detach biofouling species. In this study, inspired by the methods used in soft-robotic systems, controlled deformation of silicone elastomers via pneumatic actuation was employed to detach adherent biofilms. Using programmed surface deformation, it was possible to release > 90% of biofilm from surfaces in both laboratory and field environments. A higher substratum strain was required to remove biofilms accumulated in the field environment as compared with laboratory-grown biofilms. Further, the study indicated that substratum modulus influences the strain needed to de-bond biofilms. Surface deformation-based approaches have potential for use in the management of biofouling in a number of technological areas, including in niche applications where pneumatic actuation of surface deformation is feasible.     

The Plant Alkaloid Camptothecin as a Novel Antifouling Compound for Marine Paints: Laboratory Bioassays and Field Trials

The extensive use of copper and booster biocides in antifouling (AF) paints has raised environmental concerns and the need to develop new AF agents. In the present study, 18 alkaloids derived from terrestrial plants were initially evaluated for AF activity using laboratory bioassays with the bryozoan Bugula neritina and the barnacle Balanus albicostatus. The results showed that 4 of the 18 alkaloids were effective in inhibiting larval settlement of B. neritina, with an EC₅₀ range of 6.18 to 43.11 μM, and 15 of the 18 alkaloids inhibited larval settlement of B. albicostatus, with EC₅₀ values ranging from 1.18 to 67.58 μM. Field trials that incorporated five alkaloids respectively into paints with 20% w/w indicated an in situ AF efficiency of evodiamine, strychnine, camptothecin (CPT), and cepharanthine, with the most potent compound being CPT, which also exhibited stronger AF efficiency than the commercial antifoulants cuprous oxide and zinc pyrithione in the field over a period of 12 months. Further field trials with different CPT concentrations (0.1 to 20% w/w) in the paints suggested a concentration-dependent AF performance in the natural environment, and the effective concentrations to significantly inhibit settlement of biofoulers in the field were ≥?0.5% w/w (the efficiency of 0.5% w/w lasted for 2 months). Moreover, CPT toxicity against the crustacean Artemia salina, the planktonic microalgae Phaeodactylum tricornutum and Isochrysis galbana, was examined. The results showed that 24 h LC₅₀ of CPT against A. salina was 20.75 μM, and 96 h EC₅₀ (growth inhibition) values of CPT to P. tricornutum and I. galbana were 55.81 and 6.29 μM, respectively, indicating that CPT was comparatively less toxic than several commercial antifoulants previously reported. Our results suggest the novel potential application of CPT as an antifoulant.     

Marine environmental issues of Southeast Asia: state and development

The seas of Southeast Asia play an important role in the economy of the surrounding countries. The region's constantly expanding coastal population and development has made great demands on marine resources, with growing evidence seen in the further degradation of the marine environment and continued exploitation of living as well as non-living resources. Integrated coastal area management has never been considered in the past while environmental protection measures and policies have largely been at local or national levels. Implementation of regional study programmes less than 10 years ago and ratification of international as well as regional agreements aimed at protecting the marine environment in recent times indicate a more enlightened approach to the problem.     

Marine longitudinal biodiversity: causes and conservation

The horizontal temperature zones of the earth tend to restrict the latitudinal ranges of species but allow the possibility of exceedingly broad longitudinal dispersals. In the Tropical Zone, biodiversity on the continental shelves is not homogeneous but is concentrated in two conspicuous peaks, one in the Indo‐Pacific Ocean and the other in the Atlantic. The Indo‐Pacific biodiversity peak is located within a relatively small area called the East Indies Triangle. The Atlantic peak is located in the southern Caribbean Sea. Evidence that has been accumulated over the years indicates that each area functions as a centre of origin and evolutionary radiation. What are the causes of these concentrations and their present functions? A newly published model indicates a positive relationship between environmental temperature and the rate of speciation. While this helps to explain the generally high tropical diversity, and the negative relationship between diversity and latitude, it does not provide a reason for the longitudinal concentrations. But, other new research serves to substantiate previous indications of a positive relationship between speciation rate and species diversity. The existence of this positive feedback, together with some contributory factors, provides the reason why concentrations occur. The evolutionary radiation probably begins when the build‐up of species diversity reaches a critical level. The warm‐temperate biotas are derived from the tropics. Their northern longitudinal relationships tend to be minor but, in the southern hemisphere, the West Wind Drift is an important dispersal mechanism for both warm‐temperate and cold‐temperate species. The cold‐temperate biotas peaked in two areas, the North Pacific and the Antarctic; each has developed into a centre of origin. The continuous dispersal of well‐adapted species from the centres helps peripheral communities maintain diversity.     

Infectious diseases of marine molluscs and host responses as revealed by genomic tools

More and more infectious diseases affect marine molluscs. Some diseases have impacted commercial species including MSX and Dermo of the eastern oyster, QPX of hard clams, withering syndrome of abalone and ostreid herpesvirus 1 (OsHV-1) infections of many molluscs. Although the exact transmission mechanisms are not well understood, human activities and associated environmental changes often correlate with increased disease prevalence. For instance, hatcheries and large-scale aquaculture create high host densities, which, along with increasing ocean temperature, might have contributed to OsHV-1 epizootics in scallops and oysters. A key to understanding linkages between the environment and disease is to understand how the environment affects the host immune system. Although we might be tempted to downplay the role of immunity in invertebrates, recent advances in genomics have provided insights into host and parasite genomes and revealed surprisingly sophisticated innate immune systems in molluscs. All major innate immune pathways are found in molluscs with many immune receptors, regulators and effectors expanded. The expanded gene families provide great diversity and complexity in innate immune response, which may be key to mollusc''s defence against diverse pathogens in the absence of adaptive immunity. Further advances in host and parasite genomics should improve our understanding of genetic variation in parasite virulence and host disease resistance.     

Assessing Invasion Impact: Survey Design Considerations and Implications for Management of An Invasive Marine Plant

We use a three-year study of sheltered low shore assemblages colonised by the non-indigenous Asian kelp Undaria pinnatifida to explore survey design issues for assessing the ecological impacts of invasive species. The weight of evidence overall suggested little impact from Undaria on low shore assemblages, with control–impact contrasts that could plausibly be interpreted as impacts probably reflecting natural causes. We demonstrate that the potential for reaching incorrect conclusions regarding the impacts of invasive species using control–impact designs is greater than when such designs are used to assess traditional forms of anthropogenic impact. We suggest that a before–after control–impact framework is essential, but recognise that such an approach has a number of limitations. In particular, there is no assurance that the before–after impact site will be invaded at all, or to the extent that provides worst-case impact information for coastal managers. We discuss possible ways of assessing invasive species impacts, but suggest that the uncertainty inherent in extrapolating impact information to other places and times means that the precautionary principle should be applied, and worst-case impacts assumed, until the level of scientific uncertainty is reduced. Such an approach should only be applied, however, after an evaluation of the feasibility, costs and benefits of managing a particular pest in relation to other priorities for invasive species.     

Colonization of vineyards by phytoseiid mites: their dispersal patterns in the plot and their fate

The effect of wind and woody margins on the dispersal and population dynamics of phytoseiid mites was studied in a vine plot for a period of two years. Mites were sampled in the plot and in the surrounding vegetation (crops and natural vegetation) in order to determine phytoseiid mite abundance. The surrounding vegetation was considered to be a reservoir of phytoseiids from where the vine plot could be invaded. Directional and non-directional soil and aerial traps were placed in the plot to determine predatory mite exchange between the two areas. Colonization of the plot occurred in two stages: first, mite migration into the plot, followed by their establishment. The two-year study partially clarified the first of these two stages. Kampimodromus aberrans was the main species caught in the aerial traps. Phytoseiid mite dispersal within the vine plot seemed to be affected by both wind (direction, intensity and regularity) and phytoseiid mite density in the woody margin. However, the woody margin had a large effect only over a short distance. Some observations pointed towards an effect of other reservoir areas but it was not possible to characterize these. The population density of the phytoseiid mites in the plot increased from 1996 to 1998, but these increases are much smaller than one would expect on the basis of the number of mites migrating by air in the plot. Moreover, blocks where most mites were trapped were not the blocks where densities of phytoseiid mites on vine leaves were the largest. It therefore seems likely that not all migrants were able to develop. Their settlement pattern was not determined and this could constitute a potential research focus for the future.     

Implications of fish home range size and relocation for marine reserve function

Reserves are being used increasingly to conserve fish communities and populations under threat from overfishing, but little consideration has been given to how fish behavior might affect reserve function. This review examines the implications of how fish use space, in particular the occurrence and size of home ranges and the frequency and direction of home range relocations. Examples are drawn primarily from the literature on coral reef fishes, but the principles apply to other habitats. Reserves can protect fish species only if individuals restrict their movements to a localized home range during at least part of the life cycle. Home range sizes increase with body size. In small reserves, a significant proportion of fish whose home ranges are centered within the reserve can be exposed to fishing mortality because their home ranges include non-reserve areas. Relocation of home ranges following initial settlement increases exposure to the fishery, especially if habitat selection is frequency-dependent. Distance, barriers, and costs of movement counter such redistribution. These considerations lead to predictions that population density and mean fish size (1) will form gradients across reserve boundaries with maxima in the center of the reserve and minima outside the reserve away from the boundary; (2) will increase rapidly in newly established reserves, only later providing spillover to adjacent fisheries as density-dependent emigration begins to take effect; and (3) will be higher in reserves that are larger and have higher area:edge ratios, more habitat types, natural barriers between reserve and non-reserve areas, and higher habitat quality inside than outside the reserve. (4) Species with low mobility and weak density-dependence of space use will show the greatest increase in reserves and the strongest benefit for population reproductive capacity, but those with intermediate levels of these traits will provide the greatest spillover benefit to nearby fisheries.     

Experimental Extinction of Garlic Mustard (Alliaria petiolata) Populations: Implications for Weed Science and Conservation Biology

An assumption of weed science and conservation biology is that small populations are more vulnerable to elimination and extinction than large populations. We tested this with the invasive biennial garlic mustard (Alliaria petiolata). We compared 61 experimental populations from which every flowering plant was removed for 4 years, with 56 control populations. Whereas the majority of the control populations continued to expand in size over the 4 years, experimental populations showed a strong experimental effect, remaining stable in size, declining in size, or going extinct. Small populations were far more vulnerable to extinction than large populations: 43% of small experimental populations (initially fewer than 10 individuals) went extinct, but only 7% of large populations (initially more than 50 individuals). However, some small experimental populations persisted, and in a few cases, larger experimental populations continued to expand even though every flowering individual had been removed. These results and a simple population model suggest the importance of buried seeds in allowing this species to persist despite attempts to eradicate it.     

Characteristics of Marine Aggregates in Shallow-water Ecosystems: Implications for Disease Ecology

Marine aggregates were evaluated for their potential role in the ecology of aquatic pathogens using underwater video surveys coupled with direct collection of aggregates in modified settling cones. Six locations, two each in New York, Connecticut, and Massachusetts, were surveyed over 8 months to explore differences in the characteristics of aggregates found in habitats populated by clams (Mercenaria mercenaria) and oysters (Crassostrea virginica). Microaggregate (<500 μm) concentrations were always greater than macroaggregate (>500 μm) concentrations, but peak concentrations of macroaggregates and microaggregates, mean size of particles, and volume fraction of aggregated material varied among the six shallow-water habitats. Concentrations (colony-forming units per ml) of total heterotrophic bacteria (THB) and total mesophilic pathogenic bacteria (MPB) from samples of aggregates were significantly different among the four locations bordering Long Island Sound (LIS). The highest concentrations and enrichment factors in aggregates were observed in August for THB and in June for MPB. Significant correlations were detected for salinity and the concentrations and enrichment factors of THB in aggregates and for the concentrations and percentages of MPB in seawater samples. Significant correlations were also detected for temperature and the concentrations of MPB in aggregates and the enrichment factors for THB and MPB (marginal significance). Bacterial species identified in association with aggregates included: Vibrio cholerea, V. parahaemolyticus, V. vulnificus, V. alginolyticus, Aeromonas hydrophila, Pseudomonas aeruginosa, Escherichia coli, and Mycobacteria sp. These results have important implications for the way in which aquatic pathogens are collected, quantified, and monitored for risk-based surveillance in shallow-water ecosystems.     

海洋放线菌HSL-6抗菌物质的发酵优化与性质研究

海洋放线菌HSL-6能产生对金黄色葡萄球菌有强烈抑制作用的活性物质。对其发酵条件和理化性质进行了研究,正交实验证明,其产生抗菌活性物质的最佳条件:发酵培养基pH6.5、培养温度为28℃、振荡频率300r/min、发酵培养基配方为蔗糖2%、黄豆粉1.5%、酵母浸粉0.15%、CaCO30.05%、甘油0.20%;菌龄为36h,接种量为10%,发酵时间为96h;该抗菌活性物质具有较好的热稳定性、pH稳定性,易溶于氯仿,经薄层层析展开后在紫外光下具有发荧光的特点,纸电泳实验证实该物质是一种弱酸性物质。     

Marine ecosystem regime shifts: challenges and opportunities for ecosystem-based management

Regime shifts have been observed in marine ecosystems around the globe. These phenomena can result in dramatic changes in the provision of ecosystem services to coastal communities. Accounting for regime shifts in management clearly requires integrative, ecosystem-based management (EBM) approaches. EBM has emerged as an accepted paradigm for ocean management worldwide, yet, despite the rapid and intense development of EBM theory, implementation has languished, and many implemented or proposed EBM schemes largely ignore the special characteristics of regime shifts. Here, we first explore key aspects of regime shifts that are of critical importance to EBM, and then suggest how regime shifts can be better incorporated into EBM using the concept of integrated ecosystem assessment (IEA). An IEA uses approaches that determine the likelihood that ecological or socio-economic properties of systems will move beyond or return to acceptable bounds as defined by resource managers and policy makers. We suggest an approach for implementing IEAs for cases of regime shifts where the objectives are either avoiding an undesired state or returning to a desired condition. We discuss the suitability and short-comings of methods summarizing the status of ecosystem components, screening and prioritizing potential risks, and evaluating alternative management strategies. IEAs are evolving as an EBM approach that can address regime shifts; however, advances in statistical, analytical and simulation modelling are needed before IEAs can robustly inform tactical management in systems characterized by regime shifts.