Effects of temporal variability of disturbance on the succession in marine fouling communities in northern-central Chile

We investigated the effects of temporal variability in a disturbance regime on fouling communities at two study sites in a northern-central Chilean bay. Fouling assemblages grown on artificial settlement substrata were disturbed by mechanical removal of biomass at different time intervals. Using one single disturbance frequency (10 disturbance events over 5 months) we applied 7 different temporal disturbance treatments: a constant disturbance regime (identical intervals between disturbance events), and 6 variable treatments where both variableness and sequences of intervals between disturbance events were manipulated. Two levels of temporal variableness (low and high, i.e. disturbance events were either dispersed or highly clumped in time) in the disturbance regime were applied by modifying the time intervals between subsequent disturbance events. To investigate the temporal coupling between disturbance events and other ecological processes (e.g. larval supply and recruitment intensity), three different sequences of disturbance intervals were nested in each of the two levels of temporal variableness. Species richness, evenness, total abundance, and structure of communities that experienced the various disturbance regimes were compared at the end of the experiment (15 days after the last disturbance event). Disturbance strongly influenced the community structure and led to a decrease in evenness and total abundance but not species richness. In undisturbed reference communities, the dominant competitor Pyura chilensis (Tunicata) occupied most available space while this species was suppressed in all disturbed treatments. Surprisingly, neither temporal variableness in the disturbance regime nor the sequence of intervals between disturbance events had an effect on community structure. Temporal variability in high disturbance regimes may be of minor importance for fouling communities, because they are dominated by opportunistic species that are adapted to rapidly exploit available space

Toward a Global Regime of Vessel Anti-Fouling

Vessel anti-fouling is key to the efficient operation of ships, and essential for effective control of invasive species introduced through international shipping. Anti-Fouling Systems, however, pose their own threats to marine environments. The Anti-Fouling Convention of 2001 banned the use of organotin compounds such as Tributyltin, and created a system for adoption of alternative anti-fouling biocides. In 2011, the Marine Environmental Protection Committee of the International Maritime Organization (IMO) released guidelines on bio-fouling management record keeping, installation, inspection, cleaning, maintenance, design and construction. Though these Guidelines provide a template for more effective and environmentally sound anti-fouling control and implementation, they are not mandatory. This article proposes that the member states of the IMO adopt the 2011 Guidelines as a mandatory instrument

Dynamical Modelling and Simulation of Waste water Filtration Process by Submerged Membrane Bioreactors

A mathematical model was developed for the filtration process and the influence of aeration on Submerged Membrane Bioreactors. The dynamics of sludge attachment to and detachment from the membrane, in relation to the filtration and a strong intermittent aeration, were included in the model. The influence on the membrane fouling of intermittent aeration injected on the membrane surface, and its synchronization with intermittent filtration, were studied numerically and experimentally. For the evaluation of filtration cake development, the assumption of the presence of two cake layers (one dynamic and the other stable) was considered. The model development and simulation focused on the description of existing relationships among important system variables like mixed liquor suspended solids concentration, aeration, temperature of the sludge suspension, transmembrane pressure, and the fouling increase during the filtration process. The model obtained offers the possibility of improving the design configuration and operation strategies of Submerged Membrane Bioreactors in wastewater treatment, and it allows the of aeration-filtration cycles to be optimized

Comparative Growth and Survival of Juvenile Atlantic Cod (Gadus morhua)Cultured in Copper and Nylon Net Pens

Bio-fouling on net pens has been a major concern for the marine aquaculture industry. As cage systems increase in size, so does the surface area for the attachment of colonial organisms that create drag on the net, reduce water flow important to fish health, and increase operational expenses due to net cleaning. To solve this problem, the International Copper Association (ICA) has been developing copper alloy netting for sea cages. Copper netting has unique properties that minimize bio-fouling, reduce the risk of fish escapement, prevent predators from entering the net pen, and is recyclable. To test the alloy netting, an experiment was conducted to compare juvenile cod cultured in traditional nylon nets with cod grown in Seawire copper netting ([email protected]). Six, 0.78 m3 cages were each stocked with 200 Atlantic cod (Gadus morhua) averaging 29 ± 2.2 g and grown for 4 months in coastal waters of New Hampshire, USA. Results of the study indicated no significant differences in cod growth, survival, feed conversion ratio (FCR), specific growth rate (SGR), or Fulton’s condition factor (K) between the fish grown in the copper alloy and nylon nets. A chemical analysis was conducted on the cod and indicated no differences in copper levels in muscle, liver and gill tissues taken from the net treatments. Nylon nets with antifouling paint accumulated significantly more bio-fouling than the copper nets. Materials that were in direct contact with the copper netting (plastic cable ties) fouled heavily with hydroids indicating minimal leaching to the environment. This study describes some of the beneficial attributes of copper netting, however future studies need to be conducted over a longer period of time, on a larger scale, and in a more energetic environment to definitively test the utility of this new product

Report on the 2013 Rapid Assessment Survey of Marine Species at New England Bays and Harbors

Introduced species (i.e., non-native species that have become established in a new location) have increasingly been recognized as a concern as they have become more prevalent in marine and terrestrial environments (Mooney and Cleland 2001; Simberloff et al. 2005). The ability of introduced species to alter population, community, and ecosystem structure and function, as well as cause significant economic damage is well documented (Carlton 1989, 1996b, 2000; Cohen and Carlton 1995; Cohen et al. 1995; Elton 1958; Meinesz et al. 1993; Occhipinti-Ambrogi and Sheppard 2007; Pimentel et al. 2005; Thresher 2000). The annual economic costs incurred from managing the approximately 50,000 introduced species in the United States alone are estimated to be over $120 billion (Pimentel et al. 2005). Having a monitoring network in place to track new introductions and distributional changes of introduced species is critical for effective management, as these efforts may be more successful when species are detected before they have the chance to become established. A rapid assessment survey is one such method for early detection of introduced species. With rapid assessment surveys, a team of taxonomic experts record and monitor marine species–providing a baseline inventory of native, introduced, and cryptogenic (i.e., unknown origin) species (as defined by Carlton 1996a)–and document range expansions of previously identified species. Since 2000, five rapid assessment surveys have been conducted in New England. These surveys focus on recording species at marinas, which often are in close proximity to transportation vectors (i.e., recreational boats). Species are collected from floating docks and piers because these structures are accessible regardless of the tidal cycle. Another reason for sampling floating docks and other floating structures is that marine introduced species are often found to be more prevalent on artificial surfaces than natural surfaces (Glasby and Connell 2001; Paulay et al. 2002). The primary objectives of these surveys are to: (1) identify native, introduced, and cryptogenic marine species, (2) expand on data collected in past surveys, (3) assess the introduction status and range extensions of documented introduced species, and (4) detect new introductions. This report presents the introduced, cryptogenic, and native species recorded during the 2013 survey

Modelling of submerged membrane bioreactor: Conceptual study about link between activated slugde biokinetics, aeration and fouling process

A mathematical model was developed to simulate filtration process and aeration influence on Submerged Membrane Bioreactor (SMBR) in aerobic conditions. The biological kinetics and the dynamic effect of the sludge attachment and detachment from the membrane, in relation to the filtration and a strong intermittent aeration, were included in the model. The model was established considering soluble microbial products (SMP) formation-degradation. The fouling components responsible of pore clogging, sludge cake growth, and temporal sludge film coverage were considered during calculation of the total membrane fouling resistance. The influence of SMP, trans-membrane pressure, and mixed liquor suspended solids on specific filtration resistance of the sludge cake was also included. With this model, the membrane fouling under different SMBR operational conditions can be simulated. The influence of a larger number of very important process variables on fouling development can be well quantified. The model was developed for evaluating the influence on fouling control of an intermittent aeration of bubbles synchronized or not with the filtration cycles, taking into account the effects of shear intensity on sludge cake removal

Dockside Shellfish Aquaculture Project, Smith, B

The intent of this project was to train private dock owners and marina personnel how to deploy and maintain “spat collectors” under their docks in an effort to capture commercially important shellfish larvae, scallops and oysters in particular, with a minimum amount of effort and cost. The New Hampshire Estuaries Project (NHEP) provided major funding for this phase of the project, with addition funding from the New Hampshire Department of Environmental Services (NHDES) and the Gulf of Maine Council (GOMC). This year’s effort expands upon the pilot studies that were funded previously by the New Hampshire Coastal Program (NHCP) and the Greater Piscataqua Community Foundation (GPCF). The larvae of most shellfish are free swimming, and can be carried by the tides, currents and wind a great distance. Most of the larvae never survive due to predation and lack of suitable habitat. If it were possible to capture even a small percentage of the larvae within a suitable predator free habitat, the resulting grown out shellfish could be used to enhance the existing beds of wild population shellfish. There are such programs currently being managed, including the Wild Scallop Enhancement Program in Maine and the Oyster Gardening Project on Chesapeake Bay. AERC was able to recruit a number of volunteers, or “Shellfish Stewards”, from the entire seacoast region to join in the project. Although there were challenges, the project was a success. The scallop spat collectors proved to work efficiently with minimal loss over the winter. Lots of shellfish larvae were found growing in the spat bags, with no predators present. Unfortunately, none of the targeted species were found in the bags. The oyster bags did not work as well; only three of the nine bags were covered to date. They may weigh too much, or have fouled too heavily and sank. The bags recovered had lots of shellfish spat growing on them, just no oysters. The next logical step in future efforts with the dockside aquaculture projects would be to consider the options of placing “pre-seeded” collectors onto the sites. AERC attempted to import scallops from the Maine enhancement program last summer as a contingency plan, but the transfer never occurred due to weather and logistical problems encountered at the time. AERC would like to thank our funding agencies for their support and aid in this research. Thanks as well to all of our shellfish stewards who dedicated their dock space, time and effort to help restore an important natural resource. Special thanks to Bill Marshall of the New Castle Conservation Committee, who was instrumental in recruiting our many shellfish stewards in New Castle. Bill also assisted the AERC staff in the deployment phase and was even there to tow us out of the mud during the retrieval operations

Does settlement plate material matter? The influence of substrate type on fouling community development

Benthic community composition and ascidian abundance can differ dramatically between adjacent man-made and natural substrates. Although multiple factors, including light exposure, surface orientation, predation exposure, and habitat type, are known to contribute to these patterns, few studies have directly tested the influence of substrate identity on community development. We compared fouling communities on settlement plates composed of commonly occurring natural (granite) and artificial (concrete, high density polyethylene, and PVC) marine materials deployed from late May to mid November 2014 from a floating dock in Newcastle, NH. We sought to determine if observed patterns resulted from differential recruitment onto substrate materials or post-settlement survival and growth. To do this, half of the plates were cleaned during bi-weekly examinations, and half were left un-cleaned. Preliminary analyses indicate that community composition differs between substrate types. These results will help us understand how substrate features contribute to non-native species establishment and habitat dominance, and may inform decisions regarding material usage in marine construction. These findings also underline the importance of settlement substrate choice in scientific studies, as plate material may influence experimental conclusions

Fate and impact of organics in an immersed membrane bioreactor applied to brine denitrification and ion exchange regeneration

The application of membrane bioreactors (MBRs) to brine denitrification for ion exchange regeneration has been studied. The developed culture was capable of complete brine denitrification at 50 gNaCl.l−1. Denitrification reduced to c.60% and c.70% when salinity was respectively increased to 75 and 100 g.l−1, presumed to be due to reduced growth rate and the low imposed solids retention time (10 days). Polysaccharide secretion was not induced by stressed cells following salt shocking, implying that cell lysis did not occur. Fouling propensity, monitored by critical flux, was steady at 12–15 l.m−2.h−1 during salinity shocking and after brine recirculation, indicating that the system was stable following perturbation. Low molecular weight polysaccharide physically adsorbed onto the nitrate selective anion exchange resin during regeneration reducing exchange capacity by c.6.5% when operating up to complete exhaustion. However, based on a breakthrough threshold of 10 mgNO3−-N.l−1 the exchange capacity was comparative to that determined when using freshly produced brine for regeneration. It was concluded that a denitrification MBR was an appropriate technology for IEX spent brine reco