Towards an ecologically and economically sound biofouling control of <i>Mytilopsis leucophaeata</i> in the harbour of Antwerp

Any surface exposed to untreated water provides an opportunity for the settlement and subsequent growth of filter feeders. The cooling water conduits of a power station are an ideal habitat for such species, because they pomp untreated water from nearby seas, rivers and lakes. Settlement occurs readily and growth can be rapid until it begins to interfere with the operational systems and finally leads to their failure. This phenomenon is known as biofouling. Because of the great economical damage, caused by fouling organisms, biocides are being used to control them. Until now, the most effective and cheap control measure is chlorination. Regardless of its non-specific toxicity, chlorine-holding chemicals are used worldwide. Mytilopsis leucophaeata, the Brackish Water Mussel, is a typical estuarine species that invaded Europe in the 19th century and originates from the U.S.. But it is only since the early nineties that the magnitude of fouling problems caused by M. leucophaeata in the harbour of Antwerp, became clear. Because of the future legal limitations on biocide draining in cooling water, the use of merely chlorine will no longer be effective enough. Other methods have to be searched to prevent fouling problems, caused by M. leucophaeata. Adult mussels can shut their protective shell valves and stop byssus production to isolate their body from changes in the external environment, such as biocide-passage. The planctonic larvae are the only vulnerable life stages and thus susceptible to biocides. Hence, knowledge on the population dynamics of M. leucophaeata provides an ecologically and economically proper use of the detrimental chemicals and minimizes as such their harm in the environment and in the cooling water conduits. A model, integrating all results of the study, will allow to (1) achieve an efficient and rational use of biocides to control biofouling caused by M. leucophaeata and (2) if possible, reduce the recruitment success of M. leucophaeata by manipulation of the relevant environmental factors of the incoming cooling water

The effect of temperature and salinity on the survival of <i>Mytilopsis leucophaeata</i> larvae: the search for environmental limits

The brackish water mussel, Mytilopsis leucophaeata, is a rapidly expanding invasive bivalve in Europe with great biofouling capacities. Being a typical brackish water species with very broad habitat preferences and environmental limits, adults are extremely tolerant to fluctuations in temperature and salinity. The life cycle of mussels however, consists of two phases: (1) from fertilization until larval settlement they are pelagic, only protected by a larval soft shell and (2) after settlement, the individuals become benthic and develop a hard mytiliform shell. The fact that adult mussels can close their protective valves is the major reason why they are important fouling species and are difficult to remove once settled. Therefore, vulnerability of different larval life stages of M. leucophaeata to temperature and salinity was investigated during standardized acute 48 h experimental tests. In addition, the survival limits of the most vulnerable larval life stage were determined at different temperature-salinity combinations. Results indicated that larval stages show a differential vulnerability: 4 h old embryos were more vulnerable to changes in temperature and salinity than 2 day old larvae. Maximal survival of 4 h old embryos was found at 22°C at salinity 15. Surrounding this optimum, conditions stayed good for survival in a rather wide range: only salinities of 0 and 25 and temperatures below 10°C or above 30°C caused high embryonic mortality. Thus, even the most vulnerable larval stage in the life cycle of M. leucophaeata can be considered highly resistant to environmental conditions. Considering the broad environmental limits of adult as well as larval M. leucophaeata, we can expect this species to appear many brackish water bodies worldwide, with only colder regions potentially limiting its invasion success

Reducing the economic impact of an invasive bivalve, <i>Mytilopsis leucophaeata</i>, in the harbour of Antwerp (poster)

Any surface exposed to untreated water provides an opportunity for the settlement and subsequent growth of organisms. The cooling water conduits of a power station provides an ideal habitat for such species. Given these perfect conditions, settlement occurs readily and growth can be rapid until it begins to interfere with the operational systems and finally leads to their failure. This phenomenon is known as bio-fouling. Worldwide, mussels cause serious problems in cooling water conduits. Because of the great economical damage, caused by these fouling-organisms, biocides are being used to control them. To use these chemicals properly, knowledge of the lifecycle of these organisms is indispensable and monitoring is necessary. Using the Scheldt water as cooling water, a lot of companies in the harbour of Antwerp have problems with fouling organisms. In this research, Mytilopsis leucophaeata, the brackish water mussel, will be used as modelspecies for the study of biofouling control. The problems and possible solutions will be examined at the site of BASF, Antwerp.The objective of the project is to achieve an efficient and rational use of biocides to control bio-fouling caused by M. leucophaeata and as such minimise their harm in the environment and in the cooling water conduits.This objective is divided in four aspects:1. Population dynamics of M. leucophaeataWeekly sampling of the incoming cooling water gives us a reliable view on the population dynamics of M. leucophaeata. 2. Development of an 'early warning system' Knowledge about the population dynamics of M. leucophaeata will be used to develop an 'early warning system' to use biocides at the right time (= the fouling organisms most vulnerable stage) and in the right dosage.3. Influencing environmental factors on the lifecycle of M. leucophaeataExperimental research will test the influences of the environmental parameters on the lifecycle, possibly simplifying the prediction of or reducting the recruitment success of M. leucophaeata.4. Prediction of the recruitment success of M. leucophaeataA model will allow to (1) considerately dose biocides, dependent on the expected recruitment success and (2) if possible, reduce the recruitment success of M. leucophaeata by manipulation of the relevant environmental factors of the incoming cooling water

Quality-Controlled Small-Scale Production of a Well-Defined Bacteriophage Cocktail for Use in Human Clinical Trials

We describe the small-scale, laboratory-based, production and quality control of a cocktail, consisting of exclusively lytic bacteriophages, designed for the treatment of Pseudomonas aeruginosa and Staphylococcus aureus infections in burn wound patients. Based on succesive selection rounds three bacteriophages were retained from an initial pool of 82 P. aeruginosa and 8 S. aureus bacteriophages, specific for prevalent P. aeruginosa and S. aureus strains in the Burn Centre of the Queen Astrid Military Hospital in Brussels, Belgium. This cocktail, consisting of P. aeruginosa phages 14/1 (Myoviridae) and PNM (Podoviridae) and S. aureus phage ISP (Myoviridae) was produced and purified of endotoxin. Quality control included Stability (shelf life), determination of pyrogenicity, sterility and cytotoxicity, confirmation of the absence of temperate bacteriophages and transmission electron microscopy-based confirmation of the presence of the expected virion morphologic particles as well as of their specific interaction with the target bacteria. Bacteriophage genome and proteome analysis confirmed the lytic nature of the bacteriophages, the absence of toxin-coding genes and showed that the selected phages 14/1, PNM and ISP are close relatives of respectively F8, φKMV and phage G1. The bacteriophage cocktail is currently being evaluated in a pilot clinical study cleared by a leading Medical Ethical Committee