The effectiveness of rotating brush devices for management of vessel hull fouling

The present study tested two diver-operated rotating brush systems, coupled with suction and collection capabilities, to determine their efficacy in the management of vessel biofouling. Both rotating brush systems proved effective (>80%) in removing low-to-moderate levels of fouling from flat and curved experimental surfaces (Perspex plates). However, performance was generally poorer at removing more advanced levels of fouling. In particular, mature calcareous organisms were relatively resistant to the rotating brushes, with a high proportion (up to 50%) remaining on plates following treatment. On average, >95% of defouled material was collected and retained by both systems. The amount of lost material generally increased when treating curved plates with increasing biomass, whereas the material lost from flat plates was typically less and remained relatively constant throughout the trials. The majority (>80%) of fouling not captured by the systems was crushed by the brushes (ie non-viable). However, a diverse range of viable organisms (eg barnacles and hydroids) was lost to the environment during the defouling trials. When defouling a vessel, unintentional detachment of fouling organisms is likely to be high through physical disturbance by divers operating the devices and by associated equipment (eg hoses). Furthermore, residual biosecurity risks are also likely to remain due to diver error, persistent fouling remaining on treated surfaces and the inaccessibility of niche areas to the brush systems. To address these limitations, further research into alternative treatment methods is required.     

The role of constructed reefs in non-indigenous species introductions and range expansions

Constructed reefs can contribute to non-indigenous species (NIS) introductions or range expansions in several ways. Reef materials that retain developed fouling communities or ballast, such as decommissioned petroleum platforms, inactive or derelict ships, and bridge rubble are potential NIS vectors. Habitat provided by reefs placed in areas devoid of natural hard bottom or structure may be colonized by NIS propagules dispersed from natural or anthropogenic sources. A network of reef structures may also create NIS corridors for linking previously unconnected areas. Due to its level of offshore habitat alteration, changing environmental conditions, volume of shipping and boating traffic, and subtropical location, the Gulf of Mexico may be particularly vulnerable to NIS introductions and has a number of documented NIS. Non-indigenous or invasive species concerns have delayed and increased costs for some recent reef construction projects. The linkages between NIS and constructed reefs are reviewed, and approaches for anticipating, assessing, and controlling introductions are recommended. Using basic information about NIS risks, reef planners can begin to evaluate unintended consequences and incorporate risk management measures to reduce future introductions. Prevention is the most effective risk reduction approach because controlling marine NIS after introduction is expensive and offers limited probability for success.     

Variability in the settlement of non-indigenous species in benthic communities from an oceanic island

The introduction of non-indigenous species (NIS) in new environments represents a major threat for coastal ecosystems. A good understanding of the mechanisms and magnitude of the impact of NIS colonisation on native ecosystems is becoming increasingly crucial to develop mitigation measures and prevent new invasions. In this present study, we asked if distinct coastal benthic communities from an oceanic island can have different vulnerability to NIS colonisation process. First, PVC settlement plates were deployed for 1 year on the rocky shore of two different locations of Madeira Island (North versus South coast). Then, we implemented a mesocosm experiment where recruited plate communities were maintained under different levels of NIS propagule pressure in order to assess their vulnerability to NIS colonisation process. Results showed that NIS colonisation success was not influenced by the level of propagule pressure, but however, final colonisation patterns varied depending on the origin of the communities. This variability can be attributed to major structural differences between the preponderant species of each community and therefore to the biotic substrate they offer to colonisers. This study highlights how biotic features can alter the NIS colonisation process and importantly, shows that in an urbanisation context, the nature of the resident communities facing invasions risks needs to be closely assessed.     

Habitat selection, facilitation, and biotic settlement cues affect distribution and performance of coral recruits in French Polynesia

Habitat selection can determine the distribution and performance of individuals if the precision with which sites are chosen corresponds with exposure to risks or resources. Contrastingly, facilitation can allow persistence of individuals arriving by chance and potentially maladapted to local abiotic conditions. For marine organisms, selection of a permanent attachment site at the end of their larval stage or the presence of a facilitator can be a critical determinant of recruitment success. In coral reef ecosystems, it is well known that settling planula larvae of reef-building corals use coarse environmental cues (i.e., light) for habitat selection. Although laboratory studies suggest that larvae can also use precise biotic cues produced by crustose coralline algae (CCA) to select attachment sites, the ecological consequences of biotic cues for corals are poorly understood in situ. In a field experiment exploring the relative importance of biotic cues and variability in habitat quality to recruitment of hard corals, pocilloporid and acroporid corals recruited more frequently to one species of CCA, Titanoderma prototypum, and significantly less so to other species of CCA; these results are consistent with laboratory assays from other studies. The provision of the biotic cue accurately predicted coral recruitment rates across habitats of varying quality. At the scale of CCA, corals attached to the “preferred” CCA experienced increased survivorship while recruits attached elsewhere had lower colony growth and survivorship. For reef-building corals, the behavioral selection of habitat using chemical cues both reduces the risk of incidental mortality and indicates the presence of a facilitator.     

A trait-based approach to assess niche overlap and functional distinctiveness between non-indigenous and native species

Our understanding of the community assembly processes acting on non-indigenous species (NIS), as well as the relationship with native species is limited, especially in marine ecosystems. To overcome this knowledge gap we here develop a trait-based approach based on the functional distinctiveness metric to assess niche overlap between NIS and native species, using high-resolution data on benthic invertebrate communities in the Baltic Sea. Our results show that NIS retain a certain degree of similarity with native species, but display one or a few singular unique traits (e.g., bioturbation ability). Furthermore, we demonstrate that community assembly processes, including both environmental filtering and limiting similarity affect NIS establishment, but that their effects may be highly context dependent, as illustrated by pronounced spatial patterns in distinctiveness. Finally, our trait-based approach provides a generic framework applicable to other areas and organisms, to better understand and address biological invasions.     

How plastic can phenotypic plasticity be? The branching coral Stylophora pistillata as a model system

Phenotypic plasticity enables multicellular organisms to adjust morphologies and various life history traits to variable environmental challenges. Here, we elucidate fixed and plastic architectural rules for colony astogeny in multiple types of colonial ramets, propagated by cutting from genets of the branching coral Stylophora pistillata from Eilat, the Red Sea. We examined 16 morphometric parameters on 136 one-year old S. pistillata colonies (of seven genotypes), originating from small fragments belonging, each, to one of three single-branch types (single tips, start-up, and advanced bifurcating tips) or to structural preparative manipulations (representing a single or two growth axes). Experiments were guided by the rationale that in colonial forms, complexity of evolving phenotypic plasticity can be associated with a degree of structural modularity, where shapes are approached by erecting iterative growth patterns at different levels of coral-colony organization. Analyses revealed plastic morphometric characters at branch level, and predetermined morphometric traits at colony level (only single trait exhibited plasticity under extreme manipulation state). Therefore, under the experimental manipulations of this study, phenotypic plasticity in S. pistillata appears to be related to branch level of organization, whereas colony traits are controlled by predetermined genetic architectural rules. Each level of organization undergoes its own mode of astogeny. However, depending on the original ramet structure, the spherical 3-D colonial architecture in this species is orchestrated and assembled by both developmental trajectories at the branch level, and traits at the colony level of organization. In nature, branching colonial forms are often subjected to harsh environmental conditions that cause fragmentation of colony into ramets of different sizes and structures. Developmental traits that are plastic, responding to fragment structure and are not predetermine in controlling astogeny, allow formation of species-specific architecture product through integrated but variable developmental routes. This adaptive plasticity or regeneration is an efficient mechanism by which isolated fragments of branching coral species cope with external environmental forces.     

Rapid-freezing cytochemistry: preservation of tubular lysosomes and enzyme activity

We show that tubular structures present in phorbol ester-stimulated macrophages are sensitive to commonly used chemical fixatives (i.e., they usually become fragmented during fixation). These structures are well preserved in macrophages that are physically fixed by rapid-freezing and subsequent freeze-substitution in osmium-acetone. We have developed methods that combine rapid-freezing, freeze-substitution, and enzyme cytochemistry for preservation of these tubular structures and for detection of endocytosed material (i.e., horseradish peroxidase). This method of rapid-freeze cytochemistry may be useful in other situations where chemical fixation does not adequately preserve cell structures, particularly of membrane compartments.     

Correlation between structure and temperature in prokaryotic metabolic networks

Background  

In recent years, an extensive characterization of network structures has been made in an effort to elucidate design principles of metabolic networks, providing valuable insights into the functional organization and the evolutionary history of organisms. However, previous analyses have not discussed the effects of environmental factors (i.e., exogenous forces) in shaping network structures. In this work, we investigate the effect of temperature, which is one of the environmental factors that may have contributed to shaping structures of metabolic networks.     

Real‐time PCR detection of Didemnum perlucidum (Monniot, 1983) and Didemnum vexillum (Kott, 2002) in an applied routine marine biosecurity context

Prevention and early detection are well recognized as the best strategies for minimizing the risks posed by nonindigenous species (NIS) that have the potential to become marine pests. Central to this is the ability to rapidly and accurately identify the presence of NIS, often from complex environmental samples like biofouling and ballast water. Molecular tools have been increasingly applied to assist with the identification of NIS and can prove particularly useful for taxonomically difficult groups like ascidians. In this study, we have developed real‐time PCR assays suited to the specific identification of the ascidians Didemnum perlucidum and Didemnum vexillum. Despite being recognized as important global pests, this is the first time specific molecular detection methods have been developed that can support the early identification and detection of these species from a broad range of environmental sample types. These fast, robust and high‐throughput assays represent powerful tools for routine marine biosecurity surveillance, as detection and confirmation of the early presence of species could assist in the timely establishment of emergency responses and control strategies. This study applied the developed assays to confirm the ability to detect Didemnid eDNA in water samples. While previous work has focused on detection of marine larvae from water samples, the development of real‐time PCR assays specifically aimed at detecting eDNA of sessile invertebrate species in the marine environment represents a world first and a significant step forwards in applied marine biosecurity surveillance. Demonstrated success in the detection of D. perlucidum eDNA from water samples at sites where it could not be visually identified suggests value in incorporating such assays into biosecurity survey designs targeting Didemnid species.     

Economic and Environmental Impacts of Harmful Non-Indigenous Species in Southeast Asia

Harmful non-indigenous species (NIS) impose great economic and environmental impacts globally, but little is known about their impacts in Southeast Asia. Lack of knowledge of the magnitude of the problem hinders the allocation of appropriate resources for NIS prevention and management. We used benefit-cost analysis embedded in a Monte-Carlo simulation model and analysed economic and environmental impacts of NIS in the region to estimate the total burden of NIS in Southeast Asia. The total annual loss caused by NIS to agriculture, human health and the environment in Southeast Asia is estimated to be US$33.5 billion (5^th and 95^th percentile US$25.8–39.8 billion). Losses and costs to the agricultural sector are estimated to be nearly 90% of the total (US$23.4–33.9 billion), while the annual costs associated with human health and the environment are US$1.85 billion (US$1.4–2.5 billion) and US$2.1 billion (US$0.9–3.3 billion), respectively, although these estimates are based on conservative assumptions. We demonstrate that the economic and environmental impacts of NIS in low and middle-income regions can be considerable and that further measures, such as the adoption of regional risk assessment protocols to inform decisions on prevention and control of NIS in Southeast Asia, could be beneficial.     

Importance of geographic origin for invasion success: A case study of the North and Baltic Seas versus the Great Lakes–St. Lawrence River region

Recently, several studies indicated that species from the Ponto‐Caspian region may be evolutionarily predisposed to become nonindigenous species (NIS); however, origin of NIS established in different regions has rarely been compared to confirm these statements. More importantly, if species from certain area/s are proven to be better colonizers, management strategies to control transport vectors coming from those areas must be more stringent, as prevention of new introductions is a cheaper and more effective strategy than eradication or control of established NIS populations. To determine whether species evolved in certain areas have inherent advantages over other species in colonizing new habitats, we explored NIS established in the North and Baltic Seas and Great Lakes–St. Lawrence River regions—two areas intensively studied in concern to NIS, highly invaded by Ponto‐Caspian species and with different salinity patterns (marine vs. freshwater). We compared observed numbers of NIS in these two regions to expected numbers of NIS from major donor regions. The expected numbers were calculated based on the available species pool from donor regions, frequency of shipping transit, and an environmental match between donor and recipient regions. A total of 281 NIS established in the North and Baltic Seas and 188 in the Great Lakes–St. Lawrence River. Ponto‐Caspian taxa colonized both types of habitats, saltwater areas of the North and Baltic Seas and freshwater of the Great Lakes–St. Lawrence River, in much higher numbers than expected. Propagule pressure (i.e., number of introduced individuals or introduction effort) is of great importance for establishment success of NIS; however in our study, either shipping vector or environmental match between regions did not clarify the high numbers of Ponto‐Caspian taxa in our study areas. Although we cannot exclude the influence of other transport vectors, our findings suggest that the origin of the species plays an important role for the predisposition of successful invaders.     

Spatial and temporal variability of early post-settlement survivorship and growth in the barnacle Balanus glandula along an estuarine gradient

The performance of a species can be significantly altered by subtle changes in the physical environmental. The intertidal barnacle Balanus glandula is predominantly an open coast species in the Northeast Pacific. However, B. glandula commonly inhabits estuaries where environmental conditions such as salinity and temperature drastically differ from the open coast. We used survivorship and growth rates as a measure of performance in recently metamorphosed laboratory reared juvenile B. glandula outplanted along an environmental gradient at the mouth, mid-estuarine, and riverine end of the South Slough Estuary, Oregon, USA. Juvenile performance was highly variable over spatial and temporal scales and dependent upon existing environmental conditions. Surprisingly, along this estuarine gradient, juveniles performed better at a mid-estuarine location than at the mouth of the estuary. Typically, the riverine end of the estuary was the least suitable habitat along the estuarine gradient due to high juvenile mortality and a low growth rate. Although seasonally variable, survivorship and growth decreased with height along a vertical intertidal gradient as well. In a reciprocal transplant experiment, populations from both ends of the estuarine gradient displayed similar survivorship and growth rates. Our results demonstrate that the interactions of environmental conditions that vary temporally and spatially along a gradient strongly affect the success of an individual surviving and prospering during the early juvenile period.     

Can redistribution of breeding colonies on a landscape mitigate changing predation danger?

The reproductive success of colonially breeding species depends in part upon a trade‐off between the benefit of a dilution effect against nestling predation within larger colonies and colony conspicuousness. However, there may be no net survivorship benefit of dilution if smaller colonies are sufficiently inconspicuous. This raises the question about how the size distribution of breeding colonies on a landscape might change as the predation danger for nestlings changes. In southwest British Columbia, Canada, bald eagle Haliaeetus leucocephalus populations have increased exponentially at ～5% per year in recent decades and prey upon nestlings of colonial breeding great blue herons Ardea herodias faninni. Motivated by field data on reproductive success in relation to colony size, modeling is used to ask under which circumstances trading off a dilution benefit against colony conspicuousness can improve population reproductive success. That is, which colonial nesting distribution, dispersed and cryptic versus clumped and conspicuous, best mitigates predation danger on nestlings? When predators are territorial, the modeling predicts a dispersed nesting strategy as attack rate increases, but not as predator numbers increase. When predators are non‐territorial, the modeling predicts a dispersed nesting strategy as predator numbers and/or attack rates increase. When predators are both territorial and non‐territorial, colonial nesting within a predator's territory improves reproductive success when attack rates are low. This suggests nesting in association with territorial predators may offer decreased levels of predation when compared with nesting amongst non‐territorial predators. Thus a change in the colony size distribution of colonially breeding species might be anticipated on a landscape experiencing a change in predation danger.     

Potential biocontrol agents for biofouling on artificial structures

The accumulation of biofouling on coastal structures can lead to operational impacts and may harbour problematic organisms, including non-indigenous species. Benthic predators and grazers that can supress biofouling, and which are able to be artificially enhanced, have potential value as augmentative biocontrol agents. The ability of New Zealand native invertebrates to control biofouling on marina pontoons and wharf piles was tested. Caging experiments evaluated the ability of biocontrol to mitigate established biofouling, and to prevent fouling accumulation on defouled surfaces. On pontoons, the gastropods Haliotis iris and Cookia sulcata reduced established biofouling cover by >55% and largely prevented the accumulation of new biofouling over three months. On wharf piles C. sulcata removed 65% of biofouling biomass and reduced its cover by 73%. C. sulcata also had better retention and survival rates than other agents. Augmentative biocontrol has the potential to be an effective method to mitigate biofouling on marine structures.     

Species-specific markers for early detection of marine invertebrate invaders through eDNA methods: Gaps and priorities in GenBank as database example

Non-indigenous species (NIS) invasions are global phenomena that are the main drivers for ecosystem change and can often drastically affect the structure and function of novel ecosystems. Early detection is of prime importance for preventing the establishment and potential dispersal of NIS, making eradication and control more efficient and less costly since the species is present at very low densities. However, species at low density generally require intensive sampling efforts to be detected.An important shortcut to reduce sampling effort is to analyze environmental DNA (eDNA). Eukaryotic organisms leave traces of their presence in the environment where they live. In environments that are difficult to access, such as aquatic environments, DNA present in the water can be extracted and amplified using PCR target markers to identify the species that inhabit therein. Using species-specific markers, the presence of target species’ DNA from water samples can be detected using PCR and simple electrophoresis in agarose gel. This is an efficient and convenient approach when the target species is known that puts the focus on detection. However, a critical challenge of this methodology is the design of appropriate species-specific markers. They must be specific to one target species, without any cross-amplification even in close species. For this purpose, a DNA database with as many different species, genetic markers and haplotypes as possible is essential for genetic marker design. The principal aim of this work is to analyze the state-of-the-art of the databases, in this case GenBank, which is the most complete database in number of markers and species, in order to assess its utility in the design of species-specific primers for invasive species early detection.     

Biosecurity surveillance design: detecting non-indigenous vertebrate introductions using risk and power

Ecosystems can be severely damaged by the introduction, establishment and spread of non-indigenous species (NIS) including vertebrates, invertebrates and plants. Development and use of natural areas poses a biosecurity risk regarding the introduction of increase NIS invasion risks, so biosecurity systems including prevention and detection measures are required. Even with the most rigorous biosecurity efforts, there is potential for NIS to evade quarantine and go on to establish and spread. The cost of such an event can be great, both environmentally and financially (e.g. containment/ management or eradication). We have developed a surveillance design methodology, for an application where increased use of a natural area may result in NIS incursions, even with extensive biosecurity systems. The surveillance design methodology acknowledges heterogeneity of risk in the study area and stratifies the area to optimise surveillance deployment, achieving great efficiencies and improvement in statistical power of detection. Many of the risk decisions require lack data and so the system incorporates expert opinion with available data. The design covers the broad range of potential NIS that may be introduced by using exemplar species and a variety of surveillance system components (SSCs) (such as a combination of formal scientific surveys, trapping methods, and casual observation) distributed optimally over time and space. The mix of SSCs can be manipulated to take into account such factors as their relative financial costs and demands on expertise. The methodology has the flexibility to be applied to various groups of potential NIS (e.g. vertebrates, invertebrates and plants), and the design can evolve as data are collected (adaptive management). Overall, the surveillance design methodology allows for an efficient use of resources, providing sufficient power to detect incursions, resulting in reduced environmental and financial costs from NIS incursions.     

Redox control and the evolution of multicellularity

Redox chemistry, involving the transfer of electrons and hydrogen atoms, is central to energy conversion in respiration; in addition, control of gene expression by redox state commonly occurs in bacteria, allowing a rapid response to environmental changes, such as altered food supply. Colonial metazoans often encrust surfaces over which the food supply varies in time or space; hence, in these organisms redox control of the development of feeding structures and gastrovascular connections could be similarly adaptive, allowing colonies to adjust the timing of development and spacing of structures in response to a variable food supply and other environmental factors. Experimental perturbations of redox state in colonial hydroids support this notion of adaptive redox control, and redox signaling in metazoans may have evolved in this ecological context. At the same time, redox signaling has important consequences for the evolutionary transition from unicellular to multicellular organisms. Unlike protein or peptide signaling, redox signaling acting in concert with programmed cell death may automatically inflict a cost on those cells that "defect," that is, selfishly favor their own replication rate over that of the multicellular group. In this way, redox signaling may have allowed multicellular individuality to evolve and more easily be maintained.     

Natural chimerism in colonial urochordates

Natural chimeras are commonly distributed in the wild, challenging the traditional paradigm for the advantages of genetically homogenous entities, where uniclonality prevents within-organism conflicts. This essay focuses on the last two-decade studies on chimerism in the cosmopolitan urochordate Botryllus schlosseri, enlightening and focusing the idea of multichimeras as a primary tool for fending off the pervasiveness of super parasitic germ lines. Interacting Botryllus colonies may fuse or reject each other based on allelic compatibility on a single highly polymorphic gene locus. After fusion and establishment of a chimera, a second tier of allorecognition is developed, expressed as genetically controlled morphological resorption of one of the chimeric partners. This is followed by the third tier of allorecognition where somatic and germ cell lineages parasitism are developed. Studies revealed a complex network of costs and few suggested benefits for the state of chimerism in botryllid ascidians. Two life history traits (diversification of allorecognition allele repertoire, colonial programmed lifespan) were considered as selected to combat the major cost of chimeric associated germ cell parasitism. Three other ecological traits (heterosis, settlement of kin larvae in aggregates, multichimerism) have been suggested as selected to enhance the existence of chimerism in botryllid ascidians. Recent results revealing a fine-tuning of the chimerical somatic genetic components in response to changes in environmental conditions are discussed. Results further elucidate the possible existence of multichimeras, each made of several genotypes. It is proposed that natural multichimeras form more stable and vigorous entities, depicting a unique way for domesticating consortia of selfish cells that may otherwise seriously threaten survivorship of the entity.     

Predicting and mapping the risk of introduction of marine non-indigenous species into Great Britain and Ireland

Non-indigenous species (NIS) can have adverse environmental, economic and social impacts. Their management is now incorporated into key legislation, including the European Union (EU) Marine Strategy Framework Directive and the EU Regulation on the prevention and management of the introduction and spread of invasive alien species. Prevention of NIS introductions and the early detection of NIS following their introduction are recognised as the most effective approaches for reducing the potential impacts of NIS. This is true for most aquatic environments but especially so for the marine environment, where control and/or eradication are often not achievable. By assessing introduction vector activity, it is possible to identify coastal areas and specific locations where marine NIS may be more likely to be introduced. This study uses data relating to the activity of key introduction vectors; shipping, recreational boating and live animal aquaculture import, to estimate the relative risk of introduction of NIS around coastal regions of Great Britain and Ireland. Spatial analysis was used to create “heat” maps indicating coastal areas of increased relative risk of introduction of NIS by these vectors. The results of the present study will be crucial for the implementation of targeted vector management plans, supporting preventive strategies, and will facilitate a risk analyses of NIS threats to inform monitoring and surveillance programmes.     

Cytogenetic evidence for de novo synthesis of rRNA and involvement of nucleolar material in the organization of cell structures during spermiogenesis of Chariesterus armatus (Heteroptera, Coreidae)

The nucleolar material of Chariesterus armatus was analyzed during spermiogenesis in cell preparations impregnated with silver nitrate. Nucleolar corpuscles were observed in spermatids at the beginning of the process, showing that this organoid is also maintained after meiosis. In addition, nucleoli were seen in the round spermatids connected to the X-chromosome (bearer of the nucleolar organizer in C. armatus), indicating de novo synthesis of nucleolar material. This differs from the reorganization of ribosomal granules, transported from meiotic spermatocytes to round spermatids, where they would support protein synthesis, which is reported for other species. We also observed connections of nucleolar corpuscles to the nuclear membrane regions where the tail and the acrosome will be formed, suggesting close involvement of the nucleolar material in the formation of these structures. In addition to the nucleolar bodies, we detected silver-positive structures, which will require new approaches to clarify their role. One of these structures, observed in the cytoplasm, appears to correspond to the chromatoid body, which has been found in several organisms, but is still poorly understood; another is a complex structure to which the tail appears to be connected. We conclude that C. armatus is an appropriate model for understanding not only the synthesis of rRNA in the spermiogenesis, but also the functional meaning of the close relationship of nucleolar material with other structures during this process.