The ghost of fouling communities past: the effect of original community on subsequent recruitment

Biofouling on ships has been linked to the spread of invasive species, which has been identified as one of the current primary threats to the environment. Previous research on antifouling coatings suggested that the quantity of fouling, as well as community composition, on biocidal coatings was modified by prior fouling settlement. The experiment reported in this paper was designed to determine how preconditioning affected the rate and composition of subsequent fouling on transplanted silicone coatings. A series of 10 × 20?cm panels coated with Intersleek 700 or DC3140 were placed at three locations in Florida (Ponce Inlet, Sebastian Inlet, and Port of Miami), which were characterized by distinct fouling communities. Panels were immersed for four months, cleaned, and reciprocally transplanted among the three sites. Fouling community composition and coverage were characterized at bimonthly intervals both before and after transplantation. The original fouling community affected the subsequent fouling composition and recolonization by tunicates, sea anemones, barnacles, sponges, hydroids, and arborescent bryozoans. The community-level effects were short-term, lasting 2–4?months, but specific responses lasted up to 14?months post-transplant.     

Microbial community and biomass characteristics associated severe membrane fouling during start-up of a hybrid anoxic-oxic membrane bioreactor

In MBR, severe membrane fouling is often observed in the initial phase in which biomass is yet fully acclimated and stabilized in terms of microbial community structure and biomass characteristics. The focus of this study was to investigate the microbial community development and its influence on biomass characteristics and membrane fouling during start-up of a hybrid anoxic-oxic MBR. PCR-DGGE analysis indicated that the microbial community shifted in start-up period when a severe membrane fouling was observed. Small particle size, high fractal dimension (DF) and high EPS production, which were closely associated with microbial community, were found to be the major contributors to the severe fouling. Microbial community development was most likely the ultimate factor responsible for the severe membrane fouling.     

Bacterial communities associated with a mineral weathering profile at a sulphidic mine tailings dump in arid Western Australia

We investigated bacterial community assemblages and functions down a hill slope contaminated by tailings from a volcanogenic massive sulphide mine in arid Western Australia. Weathering of waste rock, high in S and Fe, had resulted in a varying elemental dispersal down a face of the tailings hill. Bacterial community assemblage, characterised by PCR-DGGE fingerprinting, was significantly associated with electrical conductivity (E.C.) (ρ = 0.664; P < 0.01). Analysis of mobile salts showed that E.C. values were driven by ionic S, Zn, Cl and Al. The bacterial community assemblage was directly characterised across an E.C. gradient using an oligonucleotide microarray (PhyloChip). The dominant taxa at the site were Proteobacteria, Actinobacteria and Firmicutes; however, 37 phyla were detected. The most responsive taxa to variation in E.C. was Acidobacteria (negative correlation). Patterns of heterotrophic processes (BioLog analysis) were also best explained by variation in E.C. (ρ = 0.53; P < 0.01), showing a link between primary mineral weathering by lithotrophic bacteria and abiotic processes, and secondary biogeochemical processes by heterotrophic taxa. These data significantly broaden our knowledge of the bacteria present in metallomorphic ecosystems, establish that mobile phase elements are key drivers of community structure, and that primary biogeochemical cycling is directly influencing other geochemical interactions in the samples.     

How resilient are Andean montane forest bird communities to habitat degradation?

The threatened forest habitats of the tropical Andes are reportedly being modified and destroyed 30% faster than their lowland tropical counterparts, but impacts on the hyper-diverse resident avifauna have received little systematic study. We present a baseline analysis of the effects of habitat modification on birds in a lower montane forest landscape in Ecuador, comparing avian community composition in landscape elements subjected to different levels of human modification: primary forest, secondary forest, edge habitat and agricultural land. We use data from a point count survey of 300 counts at 150 sites to test whether community composition and density of birds with different reported habitat preferences and foraging strategies change among landscape elements. Species richness and diversity were lowest in agricultural land, but on some measures, equally low in primary forest. Richness and diversity peaked in secondary forest and edge habitat, but ordination and density analysis revealed clear differences in their species composition. While secondary forest contained mostly forest-preferring species, edge habitat harboured a mix of forest and open-land birds. There was a clearly structured gradient in species composition across landscape elements, with densities of habitat specialists, foraging guilds and families varying considerably from primary forest to agricultural land. Agricultural land was characterised by an assemblage of widespread, abundant species very different from that in core forest habitats. As such, while the majority of montane forest birds appear resilient to a certain level of habitat modification, they cannot persist, and are displaced, where forest has been cleared outright. We argue that, for Andean montane forests, preservation of mature secondary forest offers flexibility in supplementing preserved primary forest areas to provide sufficient habitat for the persistence of this incredibly diverse but severely threatened bird community.     

Spatial structure in lotic macroinvertebrate communities in England and Wales: relationship with physical, chemical and anthropogenic stress variables

We describe the relationship between macroinvertebrate community composition, the physicochemical environment and anthropogenic impacts, in running water sites across a range of water qualities in England and Wales. We have also investigated the degree of spatial structure present in both the macroinvertebrate community and the measured environment. Selected explanatory variables could account for 26% of the variation in lotic macroinvertebrate assemblage composition across England and Wales. The explanatory power of the CCA model was based predominantly on a combination of local scale variables (substrate, alkalinity, urban run-off) and regional scale variables (discharge category, northing). The physicochemical gradient associated with changes in stream type from headwaters to estuary dominated assemblage composition. The influence of pollution and habitat modification were of secondary importance. There was a substantial level of spatial structure to both the physicochemical (47% of its explanatory power spatially structured) and anthropogenic stress data (63% of its explanatory power spatially structured), which resulted in a high level of predictable spatial structuring in macroinvertebrate assemblages. Almost 40% of the variation in assemblage composition accounted for by the explanatory model exhibited spatial structure. Positive spatial autocorrelation in macroinvertebrate community composition extended to sites up to 150km apart. As a consequence, community composition could be described from northing and easting with 75% of the explanatory power of the eight physicochemical variables. Our study has confirmed the importance of the longitudinal gradient within catchments, as well as the geographical position of the catchment to macroinvertebrate communities. We have also demonstrated how quantifying the spatial structure in the dataset can improve our understanding of the factors influencing macroinvertebrate community structure.     

Seasonal variations in the fouling diatom community structure from a monsoon influenced tropical estuary

Seasonal variations in the fouling diatom community from a monsoon influenced tropical estuary were investigated. The community composition did not differ significantly between stainless steel and polystyrene substrata due to dominance by Navicula spp. The experimental evidence suggests that Amphora, which is a dominant fouling diatom in temperate waters, ultimately dominates the community in tropical regions when conditions are favourable. These observations reveal that a faster onset of macrofouling interferes with the microfouling community wherein the faster recruiters that have a higher abundance in ambient waters, dominate the community. Seasonal variations were observed in the fouling diatom community. Navicula delicatula dominated during the post-monsoon and tychopelagic diatoms (Melosira and Odontella) were observed during the monsoon. Low diatom abundance was recorded during the pre-monsoon season. The results indicate that although the fouling diatom community composition does not vary between substrata, there is a seasonal change in the community depending on the physical, chemical and biological interactions.     

Seasonal variations in the fouling diatom community structure from a monsoon influenced tropical estuary

Seasonal variations in the fouling diatom community from a monsoon influenced tropical estuary were investigated. The community composition did not differ significantly between stainless steel and polystyrene substrata due to dominance by Navicula spp. The experimental evidence suggests that Amphora, which is a dominant fouling diatom in temperate waters, ultimately dominates the community in tropical regions when conditions are favourable. These observations reveal that a faster onset of macrofouling interferes with the microfouling community wherein the faster recruiters that have a higher abundance in ambient waters, dominate the community. Seasonal variations were observed in the fouling diatom community. Navicula delicatula dominated during the post-monsoon and tychopelagic diatoms (Melosira and Odontella) were observed during the monsoon. Low diatom abundance was recorded during the pre-monsoon season. The results indicate that although the fouling diatom community composition does not vary between substrata, there is a seasonal change in the community depending on the physical, chemical and biological interactions.     

Temporal and spatial variations in macrofouling of silicone fouling‐release coatings

Nontoxic, low surface free energy silicone coatings having reduced biofouling adhesion strength have been developed as an alternative to antifouling paints. Silicone coatings permit macrofouling to adhere; however, fouling can be removed easily by water pressure or light scrubbing. One of the current methods used to evaluate the performance of non‐toxic silicone fouling‐release coatings relies heavily on fouling coverage. The organismal community structure as well as total coverage can affect the ease of fouling removal from these coatings. This paper explores fouling coverage and organismal adhesion over time. Long‐term fouling coverage data were collected at four sites (in Massachusetts, Hawaii and Florida) using static immersion panels coated with silicone and oil‐amended silicone systems. Inter‐site differences in fouling coverage and community structure were observed for each coating. Intra‐site variation and temporal change in coverage of fouling was minimal, regardless of coating formulation. The extent of coverage was affected by the duration of immersion and the local environmental conditions; these factors may also have an impact on the foul‐release capability of the silicone coatings. Organismal adhesion data was collected in Hawaii and Florida. These adhesion measurements were used as a tool to discriminate and rank fouling release coatings.     

Temporal and spatial variation in the fouling of silicone coatings in Pearl Harbor, Hawaii

An antifouling or foul-release coating cannot be globally effective if it does not perform well in a range of environmental conditions, against a diversity of fouling organisms. From 1996 to 1998, the field test sites participating in the United States Navy's Office of Naval Research 6.2 Biofouling program examined global variation in the performance of 3 silicone foul-release coatings, viz. GE RTV11, Dow Corning RTV 3140, and Intersleek (International Coatings Ltd), together with a control anticorrosive coating (Ameron Protective Coatings F-150 series). At the University of Hawaii's test site in Pearl Harbor, significant differences were observed among the coatings in the rate of accumulation of fouling. The control coating failed rapidly; after 180-220 d immersion a community dominated by molluscs and sponges developed that persisted for the remainder of the experiment. Fouling of the GE and Dow Corning silicone coatings was slower, but eventually reached a similar community structure and coverage as the control coatings. The Intersleek coating remained lightly fouled throughout the experiment. Spatial variation in the structure of the community fouling the coatings was observed, but not in the extent of fouling. The rate of accumulation of fouling reflected differences among the coatings in adhesion of the tubeworm Hydroides elegans. The surface properties of these coatings may have affected the rate of fouling and the structure of the fouling community through their influence on larval settlement and subsequent interactions with other residents, predators, and the physical environment.     

Effect of Manual Brush Cleaning on Biomass and Community Structure of Microfouling Film Formed on Aluminum and Titanium Surfaces Exposed to Rapidly Flowing Seawater

Metals exposed to rapidly flowing seawater are fouled by microbes that increase heat transfer resistance. In this study, results of biochemical test methods quantitatively relating the biomass and community structure of the microfouling film on aluminum and titanium to heat transfer resistance across the metal surface during three cycles of free fouling and manual brushing showed that cleaning accelerates the rate of fouling measured as the loss of heat transfer efficiency and as microfouling film biomass. The results also showed that the rate of fouling, measured as an increase in heat transfer resistance, is faster on titanium than on aluminum but that the titanium surface is more readily cleaned. In three cycles of free fouling and cleaning with a stiff-bristle nylon brush, the free-fouling communities re-forming on aluminum became enriched in bacteria containing short-branched fatty acids as the cycling progressed. The free-fouling community on titanium revealed an increasingly diverse morphology under scanning electron microscopy that was enriched in a portion of the microeucaryotes. Brushing removed most of the biomass, but left a residual community that was relatively enriched in a portion of the bacterial assembly containing cyclopropane fatty acids on aluminum and in a more diverse community on the titanium surface. The residual communities left after cleaning of titanium revealed an increase in bacteria with short-branched fatty acids and in microeucaryotes as cleaning continued. No significant changes occurred in the residual microbial community structure left on aluminum with cleaning; it was, again, less diverse than that remaining on titanium. The residual communities secreted a twofold-larger amount of extracellular polymer, measured as the ratio of total organic carbon to lipid phosphate, than did the free-fouling community on both surfaces.     

Influence of hydrodynamic stress on the frictional drag of biofouling communities

The role of hydrodynamic wall shear stresses on the development of the fouling community structure and resulting frictional drag were examined using a commercially available fouling release coating. Immersed test panels were exposed to three different hydrodynamic treatments, one static and two dynamic (corresponding to an estimated wall shear stress of 7.0 and 25.5 Pa). The drag of the panels was measured in a hydrodynamic test chamber at discrete time intervals over 35 days. The fouling community composition on the static panels was significantly different from the organisms observed on the dynamic panels. Despite different fouling community composition, the drag forces measured on the panels were very similar. This suggests that the frictional drag of low form and soft fouling communities are similar and that there may be a stepwise increase in frictional drag associated with the presence of mature calcareous organisms.     

Succession of Fouling Communities on an Artificial Substrate of a Mussel Culture in the White Sea

The pattern of development of a fouling community, based on research data on their formation in the mussel culture in the White Sea is presented. The succession may come to an end either by the mussel community or by the community of Styela rustica, which is analogous to the natural epitbenthic biocenosis of Laminaria saccharina. It also might develop with the deletion of some stages. The presence of the mussel phase is not necessary in the development of fouling. The final stage of the fouling development is determined, apparently, by hydrological conditions.     

Marine fouling on floating installations west of Dongsha Islands,the northern South China Sea

Marine fouling on floating installations west of Dongsha Islands, the northern South China Sea, was investigated from August 1987 to October 1990. Two buoy stations were deployed at approximately 110 km and 115 km west of Dongshadao, Dongsha Islands, anchored in water at 325 and 345 m depths, and exposed for 8 and 12 months. The experimental panels were fixed on iron structure frames which were connected to the buoy and its mooring system immersed in water at different depths, and retrieved after 4, 8 and 12 months of exposure. Fouling organisms colonizing the buoys and their mooring systems were sampled after 8 and 12 months of deployment. A total of 86 species was collected and identified at these two stations and the fouling community showed a typical oceanic characteristics. Most of the species were mainly found in the top 50 m depth and a striking vertical zonation of species was also observed with depth. The distance from offshore is a major factor in determining the fouling community composition. In terms of biomass, the fouling community was dominated by pedunculate barnacles, hydroids, and algae, followed by common oysters, pearl oysters and acorn barnacles. Biomass of hard fouling organisms increased over time. Under the influence of hydrological currents propagules of communities around the Dongsha Islands may also affect the development of the fouling communities in the offshore waters.     

Grazer diversity effects on ecosystem functioning in seagrass beds

High plant species richness can enhance primary production, animal diversity, and invasion resistance. Yet theory predicts that plant and herbivore diversity, which often covary in nature, should have countervailing effects on ecosystem properties. Supporting this, we show in a seagrass system that increasing grazer diversity reduced both algal biomass and total community diversity, and facilitated dominance of a grazer‐resistant invertebrate. In parallel with previous plant results, however, grazer diversity enhanced secondary production, a critical determinant of fish yield. Although sampling explained some diversity effects, only the most diverse grazer assemblage maximized multiple ecosystem properties simultaneously, producing a distinct ecosystem state. Importantly, ecosystem responses at high grazer diversity often differed in magnitude and sign from those predicted from summed impacts of individual species. Thus, complex interactions, often opposing plant diversity effects, arose as emergent consequences of changing consumer diversity, advising caution in extrapolating conclusions from plant diversity experiments to food webs.     

Mini review: hydrodynamics of larval settlement into fouling communities

Flowing water delivers planktonic larvae to surfaces, but also dislodges them. This paper reviews experiments in the field and in laboratory flumes, as well as mathematical models, which have revealed how the interaction of ambient water motion with a developing fouling community affects larval settlement. Although mean current velocities across fouling communities in harbours are low, instantaneous velocities can be much higher due to turbulence and to the velocity oscillations of wind chop and ship wakes. As a fouling community develops, its topography becomes more complex and the range of flow microhabitats on the spatial scale of larvae increases. In spite of the prevalence of waves in shallow coastal habitats, and in spite of the importance to settlement of the fine-scale instantaneous velocities encountered by larvae, most studies of flow effects on larval settlement have focused on unidirectional currents and on temporally- and spatially-averaged aspects of the flow.     

Secondary Rain Forests are not Havens for Reptile Species in Tropical Mexico

A widely accepted biodiversity crisis in the tropics has been recently challenged by claims that secondary forests will gradually restore biodiversity losses. This prediction was examined for the herpetofauna in Quintana Roo, Mexico. Quantitative sampling (108 transects) of reptiles was undertaken monthly (January–September 2004) along a vegetation gradient covering induced grasslands, and regrowth and primary rain forests. A total of 35 species was found, 14 being present in and five showing dependence on mature forests. Lizards contributed > 90 per cent of the individuals observed. Reptile abundance and snake species richness was highest in primary forests, even though the lower abundance and richness did not differ between regrowth forest and induced grasslands. Multivariate ordinations and ANOSIM tests displayed clear differences in assemblage structure among vegetation types, mainly caused by contrasting abundances of lizard species having distinctive arboreal or terrestrial habits. There was no evidence that snake assemblages differed between secondary forests and induced grasslands. Microhabitat availability had a key role in shaping species composition through the vegetation gradient. Our results dismiss the hypothesis that secondary forests can act as reservoirs of primary forest reptile diversity on the basis that many taxa depend largely on habitat quality and have specialized life‐history traits, and that biological succession does not guarantee the recovery of assemblage complexity.     

3D imaging provides a high-resolution,volumetric approach for analyzing biofouling

A volumetric approach for determining the fouling burden on surfaces is presented, consisting of a 3D camera imaging system with fine (5?μm) resolution. Panels immersed in an estuary on the southwest coast of Florida, USA were imaged and the data were used to quantify seasonal changes in the biofouling community. Test panels, which were submerged in seawater for up to one?year, were analyzed before and after gentle scrubbing to quantify the biovolume of the total fouling community (ie soft and hard organisms) and the hard fouling community. Total biofouling ranged from 0.01 to 1.16?cm³ cm^?2 throughout the immersion period; soft fouling constituted 22–87% of the total biovolume. In the future, this approach may be used to inform numerical models of fluid–surface interfaces and to evaluate, with high resolution, the morphology of fouling organisms in response to antifouling technologies.     

Colonisation and succession of marine biofilm-dwelling ciliate assemblages on biocidal antifouling and fouling-release coatings in temperate Australia

Ciliate assemblages are often overlooked, but ubiquitous components of microbial biofilms which require a better understanding. Ciliate, diatom and bacterial colonisation were evaluated on two fouling-release (FR) coatings, viz. Intersleek 970 and Hempasil X3, and two biocidal antifouling (AF) coatings, viz. Intersmooth 360 and Interspeed 5640, in Port Phillip Bay, Australia. A total of 15 genera were identified during the 10 week deployment. Intersleek 970 displayed the most rapid fouling by ciliates, reaching 63.3(± 5.9) cells cm^?2. After 10 weeks, all four coatings were extensively fouled. However, the toxicity of the AF coatings still significantly inhibited microbial fouling compared to the FR coatings. On all treatments, colonies of sessile peritrichs dominated the ciliate assemblage in the early stage of succession, but as the biofilm matured, vagile ciliates exerted more influence on the assemblage structure. The AF coatings showed selective toxic effects, causing significant differences in the ciliate species assemblages among the treatments.     

Planktonic food chains of a highly humic lake

The development and metabolism of epilimnetic plankton from a highly humic lake was followed in late summer, when the predominant zooplankton species, Daphnia longispina, was very abundant (ca. 200 ind. l^?1). The experiment was made in two tanks: one with an unaltered plankton assemblage and one with larger zooplankton removed. The scarce phytoplankton community was also simple, consisting mainly of one Cryptomonas and two Mallomonas species. The abundance and species composition of smaller plankton was heavily influenced by grazing of Daphnia. In particular, the biomass, of heterotrophic flagellates increased after the removal of Daphnia. The biomass and production of bacterioplankton were not affected, and remained several times higher than that of phytoplankton. Bacterial production and grazing on bacteria were balanced, and when Daphnia was removed its grazing activity was compensated by flagellates. The removal of Daphnia did not affect the respiration or community net production of plankton. Among organisms smaller than zooplankton, bacteria seemed to be responsible for most of the respiration. The community net production was consistently negative even at the water surface, indicating an allochthonous carbon source. The results suggest that phytoplankton primary production was insufficient for the secondary production in the epilimnetic water of the study lake. The food requirements of bacteria and zooplankton, as well as of flagellates, each exceeded that supplied by phytoplankton primary production. The simple food chains in this experiment made it possible to reveal the functioning of the community so completely that dissolved organic matter is certainly comparable to or exceeds the importance of phytoplankton primary production as an energy and carbon source for food webs in this humic lake.