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).     

Spectrophotometric color measurement for early detection and monitoring of greening on granite buildings

This paper addresses the detection and monitoring of the development of epilithic phototrophic biofilms on the granite façade of an institutional building in Santiago de Compostela (NW Spain), and reports a case study of preventive conservation. The results provide a basis for establishing criteria for the early detection of phototrophic colonization (greening) and for monitoring its development on granite buildings by the use of color changes recorded with a portable spectrophotometer and represented in the CIELAB color space. The results show that parameter b* (associated with changes of yellowness-blueness) provides the earliest indication of colonization and varies most over time, so that it is most important in determining the total color change. The limit of perception of the greening on a granite surface was also established in a psycho-physical experiment, as Δb*: +0.59 CIELAB units that correspond, in the present study, to 6.3 μg of biomass dry weight cm^?2 and (8.43 ± 0.24) × 10^?3 μg of extracted chlorophyll a cm^?2.     

Laboratory culture and evaluation of the tubeworm Ficopomatus enigmaticus for biofouling studies

Ficopomatus enigmaticus, a euryhaline tube-building polychaete worm with a subtropical to temperate distribution, is an increasingly problematic fouling organism. In this study, laboratory protocols for maintaining adult broodstock, destructive spawning, larval culture and a settlement bioassay were developed. The method routinely yielded approximately 200 larvae per spawning adult. The mean number of eggs released by females was 1517 and the mean number of spermatozoids per male was 4.425?×?10⁶. Fertilisation success, using an initial concentration of 2.5?×?10⁶ spermatozoids and 45?eggs?ml^?1, was 76% after a contact time of 60?min. The first cleavage occurred after 20?min and the trocophore larval stage was attained by 18?h. Metatrochophores were observed 4?d post-fertilisation and were competent to settle 1?day later. The proportion of larvae that settled after 48?h was surface-dependent: 10.24% on glass, 1.39% on polystyrene and 11.07% on a poly(dimethylsiloxane) elastomer. The presence of a biofilm on glass increased the rate of settlement 7-fold compared to clean glass.     

Marine antifouling laboratory bioassays: an overview of their diversity

In aquatic environments, biofouling is a natural process of colonization of submerged surfaces, either living or artificial, involving a wide range of organisms from bacteria to invertebrates. Antifouling can be defined as preventing the attachment of organisms onto surfaces. This article reviews the laboratory bioassays that have been developed for studying the control of algae and invertebrates by epibiosis (chemical ecology) and the screening of new active compounds (natural products and biocides) to inhibit settlement or adhesion, ie fouling-release coatings. The assays utilize a range of organisms (mainly marine bacteria, diatoms, algae, barnacles). The main attributes of assays for micro- and macroorganisms are described in terms of their main characteristics and depending on the biological process assessed (growth, adhesion, toxicity, behavior). The validation of bioassays is also discussed.     

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.     

Marine macroalgae and their associated microbiomes as a source of antimicrobial chemical diversity

ABSTRACT

This article reviews the role of microbial biofilms in infection, and the antimicrobial chemical diversity of marine macroalgae and their associated microbiomes. Antimicrobial resistance (AMR) represents one of the major health threats faced by humanity over the next few years. To prevent a global epidemic of antimicrobial-resistant infections, the discovery of new antimicrobials and antibiotics, better anti-infection strategies and diagnostics, and changes to our current use of antibiotics have all become of paramount importance. Numerous studies investigating the bioactivities of seaweed extracts as well as their secondary and primary metabolites highlight the vast biochemical diversity of seaweeds, with new modes of action making them ideal sources for the discovery of novel antimicrobial bioactive compounds of pharmaceutical interest. In recent years, researchers have focused on characterizing the endophytic and epiphytic microbiomes of various algal species in an attempt to elucidate host-microbe interactions as well as to understand the function of microbial communities. Although environmental and host-associated factors crucially shape microbial composition, microbial mutualistic and obligate symbionts are often found to play a fundamental role in regulating many aspects of host fitness involving ecophysiology and metabolism. In particular, algal ‘core’ epiphytic bacterial communities play an important role in the protection of surfaces from biofouling, pathogens and grazers through the production of bioactive metabolites. Together, marine macroalgae and their associated microbiomes represent unique biological systems offering great potential for the isolation and identification of novel compounds and strategies to counteract the rise and dissemination of AMR.     

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.     

Effectiveness of dry heat as a seed sterilisation technique: Implications for ex situ conservation

Seed-borne pathogens are a daily issue for ex situ collection managers who try to solve it using various chemicals more or less harmful to the staff and the plant material stored. The most common physical method for seed sterilisation is moist heat, in contrast to dry heat which is used much less frequently. Consequently, the efficiency of dry heat as disinfection method and the behaviour of seeds undergoing this treatment are currently poorly known, especially for wild species. In this study, seed viability was estimated by performing germination tests according to standard procedures. Germination tests were conducted on 13,200 seeds from 66 wild species of temperate regions belonging to 22 different families. Results indicate that dry seeds exposed to 60°C during 1hour were less infected by seed-borne pathogens in 14% of the cases, whereas no change has been registered in the other cases. For all 66 studied species, no decrease in germination percentage was detected after the heat treatment. Given its positive effect on infection control without affecting seed viability, dry heat treatment as proposed here opens opportunities for seed bank managers, but also for the disinfection of herbarium collections.     

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.     

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.     

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.     

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.