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Marine Systems (marine + system)

Distribution by Scientific Domains

Life Sciences	81%
Earth and Environmental Science	13%
2 Other Domains	6%

Distribution within Life Sciences

Ecology & Organismal Biology	45%
Conservation Science	9%
Applied Microbiology	6%
7 Other Subdomains	40%

Selected Abstracts

Marine systems: moving into the genomics era

MARINE ECOLOGY, Issue 1 2005
Karen Wilson
Abstract The study of biological systems has been revolutionized by the use of genomic technologies. Most of the knowledge gathered over the last few years refers to terrestrial models. The study of marine systems using genomic technologies has, apart from a focus on microbial systems, been generally neglected although there are signs that this situation may be changing. This review analyses recent progress made in the field of marine genomics and identifies the broad areas in which this new technology is having the greatest impacts. These studies include comparative, functional and environmental genomics of metazoan animals. In many cases, as well as benefiting marine science, studies on marine taxa are having wide-ranging impacts on our global understanding of genomes and genomics. [source]

Archaeal diversity and a gene for ammonia oxidation are coupled to oceanic circulation

ENVIRONMENTAL MICROBIOLOGY, Issue 4 2009
Pierre E. Galand
Summary Evidence of microbial zonation in the open ocean is rapidly accumulating, but while the distribution of communities is often described according to depth, the other physical factors structuring microbial diversity and function remain poorly understood. Here we identify three different water masses in the North Water (eastern Canadian Arctic), defined by distinct temperature and salinity characteristics, and show that they contained distinct archaeal communities. Moreover, we found that one of the water masses contained an increased abundance of the archaeal alpha-subunit of the ammonia monooxygenase gene (amoA) and accounted for 70% of the amoA gene detected overall. This indicates likely differences in putative biogeochemical capacities among different water masses. The ensemble of our results strongly suggest that the widely accepted view of depth stratification did not explain microbial diversity, but rather that parent water masses provide the framework for predicting communities and potential microbial function in an Arctic marine system. Our results emphasize that microbial distributions are strongly influenced by oceanic circulation, implying that shifting currents and water mass boundaries resulting from climate change may well impact patterns of microbial diversity by displacing whole biomes from their historic distributions. This relocation could have the potential to establish a substantially different geography of microbial-driven biogeochemical processes and associated oceanic production. [source]

Testing the abundant-centre hypothesis using intertidal porcelain crabs along the Chilean coast: linking abundance and life-history variation

JOURNAL OF BIOGEOGRAPHY, Issue 3 2010
Marcelo M. Rivadeneira
Abstract Aim, The abundant-centre hypothesis (ACH) is based on the assumption that physiological constraints limit populations at the edges of their distributional range, yet the geographical variation of physiological performance or life-history traits has rarely been examined. Here we examine the applicability of the ACH in a marine system by testing whether physiological predictions are reflected in large-scale variations of life-history traits. Location, The Chilean coast (18°,42° S), encompassing more than 2500 km along the Pacific coast of South America. Methods, Five porcelain crab species (Petrolisthes granulosus, Petrolisthes laevigatus, Petrolisthes tuberculatus, Petrolisthes violaceus and Allopetrolisthes angulosus) were sampled on intertidal boulder beaches at 13 sampling sites. For each species and site we evaluated: (1) relative abundance (density), (2) maximum size, (3) size at maturity, (4) sex ratio, (5) proportion of ovigerous females, and (6) presence of recruits. The shape of the spatial distribution of each trait was evaluated statistically against the prediction of four hypothetical models (normal, ramped-south, ramped-north and abundant-edge). Results, The relative abundance and life-history traits showed different spatial patterns among species. Relative abundance (across sites) was fitted by a normal model in only two species. No model fitted the spatial variation in body size and size at first maturity, which showed a slight but monotonic poleward increase in all species. Sex ratio showed a prominent hump-shaped pattern, with females prevailing in the centre of the ranges and males dominating towards the range boundaries; this pattern was statistically significant in three of the five studied species. The proportion of ovigerous females showed no clear latitudinal trends, and mature individuals were observed across most of the geographical range of the species. However, recruits tended to be absent towards the southern (poleward) boundaries of the distribution. Main conclusions, The ACH does not apply to all species equally. The link between abundance and life-history traits is complex and variable among the porcelain crab species studied. Overall, the observed patterns were consistent with the idea that equatorward boundaries might be controlled by physiological restrictions mainly affecting adult survival, whereas poleward boundaries might be shaped by limitations in reproductive output and larval survival. Our results underline the importance of incorporating ecological, physiological and life-history studies in future tests of the ACH. [source]

High-density polyethylene (HDPE)-degrading potential bacteria from marine ecosystem of Gulf of Mannar, India

LETTERS IN APPLIED MICROBIOLOGY, Issue 2 2010
V. Balasubramanian
Abstract Aims:, Assessment of high-density polyethylene (HDPE)-degrading bacteria isolated from plastic waste dumpsites of Gulf of Mannar. Methods and Results:, Rationally, 15 bacteria (GMB1-GMB15) were isolated by enrichment technique. GMB5 and GMB7 were selected for further studies based on their efficiency to degrade the HDPE and identified as Arthrobacter sp. and Pseudomonas sp., respectively. Assessed weight loss of HDPE after 30 days of incubation was nearly 12% for Arthrobacter sp. and 15% for Pseudomonas sp. The bacterial adhesion to hydrocarbon (BATH) assay showed that the cell surface hydrophobicity of Pseudomonas sp. was higher than Arthrobacter sp. Both fluorescein diacetate hydrolysis and protein content of the biofilm were used to test the viability and protein density of the biomass. Acute peak elevation was observed between 2 and 5 days of inoculation for both bacteria. Fourier transform infrared (FT-IR) spectrum showed that keto carbonyl bond index (KCBI), Ester carbonyl bond index (ECBI) and Vinyl bond index (VBI) were increased indicating changes in functional group(s) and/or side chain modification confirming the biodegradation. Conclusion:, The results pose us to suggest that both Pseudomonas sp. and Arthrobacter sp. were proven efficient to degrade HDPE, albeit the former was more efficacious, yet the ability of latter cannot be neglected. Significance and Impact of the Study:, Recent alarm on ecological threats to marine system is dumping plastic waste in the marine ecosystem and coastal arena by anthropogenic activity. In maintenance phase of the plastic-derived polyethylene waste, the microbial degradation plays a major role; the information accomplished in this work will be the initiating point for the degradation of polyethylene by indigenous bacterial population in the marine ecosystem and provides a novel eco-friendly solution in eco-management. [source]

Obstacles to Bottom-Up Implementation of Marine Ecosystem Management

CONSERVATION BIOLOGY, Issue 5 2008
KIRSTEN E. EVANS
manejo de ecosistemas; manejo marino basado en ecosistemas; participación de partes interesadas; planificación de la conservación Abstract:,Ecosystem management (EM) offers a means to address multiple threats to marine resources. Despite recognition of the importance of stakeholder involvement, most efforts to implement EM in marine systems are the product of top-down regulatory control. We describe a rare, stakeholder-driven attempt to implement EM from the bottom up in San Juan County, Washington (U.S.A.). A citizens advisory group led a 2-year, highly participatory effort to develop an ecosystem-based management plan, guided by a preexisting conservation-planning framework. A key innovation was to incorporate social dimensions by designating both sociocultural and biodiversity targets in the planning process. Multiple obstacles hindered implementation of EM in this setting. Despite using a surrogate scheme, the information-related transaction costs of planning were substantial: information deficits prevented assessment of some biodiversity targets and insufficient resources combined with information deficits prevented scientific assessment of the sociocultural targets. Substantial uncertainty, practical constraints to stakeholder involvement, and the existence of multiple, potentially conflicting, objectives increased negotiation-related costs. Although information deficits and uncertainty, coupled with underinvestment in the transaction costs of planning, could reduce the long-term effectiveness of the plan itself, the social capital and momentum developed through the planning process could yield unforeseeable future gains in protection of marine resources. The obstacles we identified here will require early and sustained attention in efforts to implement ecosystem management in other grassroots settings. Resumen:,El manejo de ecosistemas es un medio para abordar múltiples amenazas a los recursos marinos. No obstante el reconocimiento de la importancia de la participación de las partes interesadas, la mayoría de los esfuerzos para implementar el manejo de ecosistemas en sistemas marinos son producto del control normativo de arriba hacia abajo. Describimos un intento raro, conducido por las partes interesadas, por implementar el manejo del ecosistema de abajo hacia arriba en el Condado San Juan, Washington (E.U.A.). Un grupo consultivo de ciudadanos dirigió un esfuerzo altamente participativo para desarrollar un plan de manejo basado en el ecosistema, guiados por un marco de planificación de la conservación preexistente. Una innovación clave fue la incorporación de dimensiones sociales al incluir objetivos tanto socioculturales como de biodiversidad en el proceso de planificación. Múltiples obstáculos dificultaron la implementación del manejo del ecosistema en este escenario. No obstante que se utilizó un plan sustituto, los costos de transacción de la planificación relacionados con la información fueron mayores de lo que el grupo pudo superar: los déficits de información impidieron la evaluación de algunos objetivos de biodiversidad y la insuficiencia de recursos combinada con los déficits de información impidieron la evaluación científica de los objetivos socioculturales. Los costos relacionados con la negociación incrementaron por la incertidumbre, por limitaciones prácticas en la participación de partes interesadas y la existencia de objetivos múltiples, potencialmente conflictivos. Aunque los déficits de información y la incertidumbre, aunados con la baja inversión en los costos de transacción de la planificación, pudieran reducir la efectividad a largo plazo del plan mismo, el capital social y el ímpetu desarrollados durante el proceso de planificación podrían producir ganancias futuras imprevisibles para la protección de recursos marinos. Los obstáculos que identificamos aquí requerirán de atención temprana y sostenida en los esfuerzos para implementar el manejo de ecosistemas en otros escenarios de base popular. [source]

Predicting the number of ecologically harmful exotic species in an aquatic system

DIVERSITY AND DISTRIBUTIONS, Issue 2 2008
Anthony Ricciardi
ABSTRACT Most introduced species apparently have little impact on native biodiversity, but the proliferation of human vectors that transport species worldwide increases the probability of a region being affected by high-impact invaders , i.e. those that cause severe declines in native species populations. Our study determined whether the number of high-impact invaders can be predicted from the total number of invaders in an area, after controlling for species,area effects. These two variables are positively correlated in a set of 16 invaded freshwater and marine systems from around the world. The relationship is a simple linear function; there is no evidence of synergistic or antagonistic effects of invaders across systems. A similar relationship is found for introduced freshwater fishes across 149 regions. In both data sets, high-impact invaders comprise approximately 10% of the total number of invaders. Although the mechanism driving this correlation is likely a sampling effect, it is not simply the proportional sampling of a constant number of repeat-offenders; in most cases, an invader is not reported to have strong impacts on native species in the majority of regions it invades. These findings link vector activity and the negative impacts of introduced species on biodiversity, and thus justify management efforts to reduce invasion rates even where numerous invasions have already occurred. [source]

A cross-system synthesis of consumer and nutrient resource control on producer biomass

ECOLOGY LETTERS, Issue 7 2008
Daniel S. Gruner
Abstract Nutrient availability and herbivory control the biomass of primary producer communities to varying degrees across ecosystems. Ecological theory, individual experiments in many different systems, and system-specific quantitative reviews have suggested that (i) bottom,up control is pervasive but top,down control is more influential in aquatic habitats relative to terrestrial systems and (ii) bottom,up and top,down forces are interdependent, with statistical interactions that synergize or dampen relative influences on producer biomass. We used simple dynamic models to review ecological mechanisms that generate independent vs. interactive responses of community-level biomass. We calibrated these mechanistic predictions with the metrics of factorial meta-analysis and tested their prevalence across freshwater, marine and terrestrial ecosystems with a comprehensive meta-analysis of 191 factorial manipulations of herbivores and nutrients. Our analysis showed that producer community biomass increased with fertilization across all systems, although increases were greatest in freshwater habitats. Herbivore removal generally increased producer biomass in both freshwater and marine systems, but effects were inconsistent on land. With the exception of marine temperate rocky reef systems that showed positive synergism of nutrient enrichment and herbivore removal, experimental studies showed limited support for statistical interactions between nutrient and herbivory treatments on producer biomass. Top,down control of herbivores, compensatory behaviour of multiple herbivore guilds, spatial and temporal heterogeneity of interactions, and herbivore-mediated nutrient recycling may lower the probability of consistent interactive effects on producer biomass. Continuing studies should expand the temporal and spatial scales of experiments, particularly in understudied terrestrial systems; broaden factorial designs to manipulate independently multiple producer resources (e.g. nitrogen, phosphorus, light), multiple herbivore taxa or guilds (e.g. vertebrates and invertebrates) and multiple trophic levels; and , in addition to measuring producer biomass , assess the responses of species diversity, community composition and nutrient status. [source]

Reconciling differences in trophic control in mid-latitude marine ecosystems

ECOLOGY LETTERS, Issue 10 2006
Kenneth T. Frank
Abstract The dependence of long-term fishery yields on primary productivity, largely based on cross-system comparisons and without reference to the potential dynamic character of this relationship, has long been considered strong evidence for bottom-up control in marine systems. We examined time series of intensive empirical observations from nine heavily exploited regions in the western North Atlantic and find evidence of spatial variance of trophic control. Top-down control dominated in northern areas, the dynamics evolved from bottom-up to top-down in an intermediate region, and bottom-up control governed the southern areas. A simplified, trophic control diagram was developed accounting for top-down and bottom-up forcing within a larger region whose base state dynamics are bottom-up and can accommodate time-varying dynamics. Species diversity and ocean temperature co-varied, being relatively high in southern areas and lower in the north, mirroring the shifting pattern of trophic control. A combination of compensatory population dynamics and accelerated demographic rates in southern areas seems to account for the greater stability of the predator species complex in this region. [source]

Allometric scaling of maximum population density: a common rule for marine phytoplankton and terrestrial plants

ECOLOGY LETTERS, Issue 5 2002
Andrea Belgrano
A primary goal of macroecology is to identify principles that apply across varied ecosystems and taxonomic groups. Here we show that the allometric relationship observed between maximum abundance and body size for terrestrial plants can be extended to predict maximum population densities of marine phytoplankton. These results imply that the abundance of primary producers is similarly constrained in terrestrial and marine systems by rates of energy supply as dictated by a common allometric scaling law. They also highlight the existence of general mechanisms linking rates of individual metabolism to emergent properties of ecosystems. [source]

Improved Comet assay for the assessment of UV genotoxicity in Mediterranean sea urchin eggs

ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2008
Sarah Nahon
Abstract Gametes and embryos of broadcast spawners are exposed to a wide range of chemical and physical stressors which may alone, or in conjunction, have serious consequences on reproductive outcomes. In this study, two Mediterranean echinoid species, Paracentrotus lividus and Sphaerechinus granularis, were chosen as models to study the genotoxicity of UV radiation (UVR) on the eggs of broadcast-spawning marine invertebrates. The single cell gel electrophoresis, or Comet assay, was successfully adapted to assess DNA strand breakage in sea urchin eggs. The results demonstrated that the genetic material of sea urchin eggs is susceptible to environmentally realistic UV exposure. The induction of DNA damage in the irradiated unfertilized eggs suggests that the previously described defense mechanisms in sea urchin eggs do not completely protect the egg's DNA against UV toxicity. Taken together, our results suggest that UV-impairment of the genetic integrity of the eggs might have a role in postfertilization failures and abnormal embryonic development. Although both species were vulnerable to UVR, embryonic development was less dramatically impaired in P.Lividus. This observation supports the postulation that species inhabiting shallower environments possess more efficient mechanisms to overcome UV-induced DNA alterations. The present demonstration of the utility and sensitivity of the Comet assay to evaluate DNA integrity in eggs from marine invertebrates opens new perspectives for monitoring the long-term effects of environmental exposure on populations and for the routine screening of substances for genotoxicity in marine systems. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. [source]

Relative abundance and diversity of ammonia-oxidizing archaea and bacteria in the San Francisco Bay estuary

ENVIRONMENTAL MICROBIOLOGY, Issue 11 2008
Annika C. Mosier
Summary Ammonia oxidation in marine and estuarine sediments plays a pivotal role in the cycling and removal of nitrogen. Recent reports have shown that the newly discovered ammonia-oxidizing archaea can be both abundant and diverse in aquatic and terrestrial ecosystems. In this study, we examined the abundance and diversity of ammonia-oxidizing archaea (AOA) and betaproteobacteria (,-AOB) across physicochemical gradients in San Francisco Bay , the largest estuary on the west coast of the USA. In contrast to reports that AOA are far more abundant than ,-AOB in both terrestrial and marine systems, our quantitative PCR estimates indicated that ,-AOB amoA (encoding ammonia monooxygenase subunit A) copy numbers were greater than AOA amoA in most of the estuary. Ammonia-oxidizing archaea were only more pervasive than ,-AOB in the low-salinity region of the estuary. Both AOA and ,-AOB communities exhibited distinct spatial structure within the estuary. AOA amoA sequences from the north part of the estuary formed a large and distinct low-salinity phylogenetic group. The majority of the ,-AOB sequences were closely related to other marine/estuarine Nitrosomonas -like and Nitrosospira -like sequences. Both ammonia-oxidizer community composition and abundance were strongly correlated with salinity. Ammonia-oxidizing enrichment cultures contained AOA and ,-AOB amoA sequences with high similarity to environmental sequences. Overall, this study significantly enhances our understanding of estuarine ammonia-oxidizing microbial communities and highlights the environmental conditions and niches under which different AOA and ,-AOB phylotypes may thrive. [source]

Polyphyletic photosynthetic reaction centre genes in oligotrophic marine Gammaproteobacteria

ENVIRONMENTAL MICROBIOLOGY, Issue 6 2007
Jang-Cheon Cho
Summary Ecological studies indicate that aerobic anoxygenic phototrophic bacteria (AAP) that use bacteriochlorophyll to support phototrophic electron transport are widely distributed in the oceans. All cultivated marine AAP are alpha-3 and alpha-4 Proteobacteria, but metagenomic evidence indicates that uncultured AAP Gammaproteobacteria are important members of ocean surface microbial communities. Here we report the description of obligately oligotrophic, marine Gammaproteobacteria that have genes for aerobic anoxygenic photosynthesis. Three strains belonging to the OM60 clade were isolated in autoclaved seawater media. Polymerase chain reaction assays for the pufM gene show that these strains contain photosynthetic reaction centre genes. DNA sequencing and phylogenetic analysis indicate that the pufM genes are polyphyletic, suggesting multiple instances of lateral gene transfer. Peptide sequences from six photosynthesis genes (pufL, pufM, pufC, pufB, pufA and puhA) were detected by proteomic analyses of strain HTCC2080 cells grown aerobically in seawater. They closely match predicted peptides from an environmental seawater bacterial artificial chromosome clone of gammaproteobacterial origin, thus identifying the OM60 clade as a significant source of gammaproteobacterial AAP genes in marine systems. The cell yield and rate of growth of HTCC2080 in autoclaved, aerobic seawater increased in the light. These findings identify the OM60 clade as a source of Gammaproteobacteria AAP genes in coastal oceans, and demonstrate that aerobic, anoxygenic photosynthetic metabolism can enhance the productivity of marine oligotrophic bacteria that also grow heterotrophically in darkness. [source]

Efficacy of intervention strategies for bioremediation of crude oil in marine systems and effects on indigenous hydrocarbonoclastic bacteria

ENVIRONMENTAL MICROBIOLOGY, Issue 6 2007
Boyd A. McKew
Summary There is little information on how different strategies for the bioremediation of marine oil spills influence the key indigenous hydrocarbon-degrading bacteria (hydrocarbonoclastic bacteria, HCB), and hence their remediation efficacy. Therefore, we have used quantitative polymerase chain reaction to analyse changes in concentrations of HCB in response to intervention strategies applied to experimental microcosms. Biostimulation with nutrients (N and P) produced no measurable increase in either biodegradation or concentration of HCB within the first 5 days, but after 15 days there was a significant increase (29%; P < 0.05) in degradation of n -alkanes, and an increase of one order of magnitude in concentration of Thalassolituus (to 107 cells ml,1). Rhamnolipid bioemulsifier additions alone had little effect on biodegradation, but, in combination with nutrient additions, provoked a significant increase: 59% (P < 0.05) more n -alkane degradation by 5 days than was achieved with nutrient additions alone. The very low Alcanivorax cell concentrations in the microcosms were hardly influenced by addition of nutrients or bioemulsifier, but strongly increased after their combined addition, reflecting the synergistic action of the two types of biostimulatory agents. Bioaugmentation with Thalassolituus positively influenced hydrocarbon degradation only during the initial 5 days and only of the n -alkane fraction. Bioaugmentation with Alcanivorax was clearly much more effective, resulting in 73% greater degradation of n -alkanes, 59% of branched alkanes, and 28% of polynuclear aromatic hydrocarbons, in the first 5 days than that obtained through nutrient addition alone (P < 0.01). Enhanced degradation due to augmentation with Alcanivorax continued throughout the 30-day period of the experiment. In addition to providing insight into the factors limiting oil biodegradation over time, and the competition and synergism between HCB, these results add weight to the use of bioaugmentation in oil pollution mitigation strategies. [source]

Ecological repercussions of historical fish extraction from the Southern Ocean

FISH AND FISHERIES, Issue 1 2009
David G Ainley
Abstract A major mid-1980s shift in ecological structure of significant portions of the Southern Ocean was partially due to the serial depletion of fish by intensive industrial fishing, rather than solely to climate factors as previously hypothesized. Over a brief period (1969,1973), several finfish stocks were on average reduced to <50%, and finally (mid-1980s) to <20%, of original size. Despite management actions, few stocks have recovered and some are still declining. Most affected species exhibit K-selected life-history patterns, and before exploitation presumably fluctuated in accordance with infrequent strong year classes, as is true of such fish elsewhere. A climate regime, the Southern Annular Mode, once oscillated between two states, but has remained in its ,positive mode' since the time of the fish extraction. This may have increased finfish vulnerability to exploitation. As breeding stocks decreased, we hypothesize that availability of annually produced juvenile fish fed upon by upper-level predators remained low. Correlations between predator populations and fish biomass in predator foraging areas indicate that southern elephant seal Mirounga leonina, Antarctic fur seal Arctocephalus gazella, gentoo penguin Pygoscelis papua, macaroni penguin Eudyptes chrysolphus and ,imperial' shag Phalacrocorax spp. , all feeding extensively on these fish, and monitored at Marion, Crozet, Kerguelen, Heard, South Georgia, South Orkney and South Shetland Islands, where fishing was concentrated , declined simultaneously during the two periods of heavy fishing. These patterns indicate the past importance of demersal fish as prey in Antarctic marine systems, but determining these interactions' ecological mechanisms may now be impossible. [source]

Myths and moderation in marine ,metapopulations'?

FISH AND FISHERIES, Issue 1 2002
R Kent Smedbol
Abstract The metapopulation concept is appearing with increasing frequency in the marine population dynamics and genetics literature, though its applicability to marine systems remains an open question. Moreover, in recent years, the meaning of the term ,metapopulation' has become blurred, concomitant with its increasing use. In this paper, we summarize the concept of metapopulation dynamics and the associated theoretical assumptions. We call for a stricter definition and use of the term ,metapopulation', critically evaluate the applicability of metapopulation theory to marine population dynamics and its use in the related literature, and consider two published case-studies that investigate metapopulation structuring in specific marine populations. Finally, we urge scientists to carefully articulate what is meant by the term ,metapopulation' and to use appropriate citations in the primary literature to circumvent the potential for nebulous (and possibly damaging) conclusions in the future. [source]

Freshwater and marine virioplankton: a brief overview of commonalities and differences

FRESHWATER BIOLOGY, Issue 6 2008
STEVEN W. WILHELM
Summary 1. Viruses are a pervasive component of microbial food webs in both marine and freshwater systems. The abundance of viruses in individual aquatic systems appears to be independent of salinity but related to the biomass of primary and secondary producers as well as seasonal effects. Burst size, virus production rate and the percentage of microbial cells carrying a viral burden also appear to be more closely correlated to trophic status than to salinity. 2. In marine environments, the roles of planktonic viruses as regulators of carbon and nutrient cycling as well as microbial community structure have been a focus of numerous studies, yet the roles of freshwater virioplankton remain much less studied. Nevertheless, a survey of published freshwater studies demonstrates that virioplankton recycle important quantities of growth-limiting nutrients from hosts via generation of dead particulate and dissolved organic matter during cell lysis, and suggests that both the chemical speciation and concentration of these organic compounds and nutrients may have important influences on the microbial community. 3. Parallel observations on the spatial patterns and dynamics of microbial mortality due to viruses or grazing are more advanced in freshwaters than in marine environments. However, the constraints that determine whether virus- or grazer-mediated mortality dominates are not yet understood in either environment. 4. Application of molecular approaches has facilitated the examination of the diversity and ecological dynamics of specific viral populations and entire communities. The depth of detail achieved in marine environments towards characterizing these populations and communities is just beginning to be matched in freshwater systems. The few available data suggest that viruses targeting-related hosts in freshwater and marine systems may be genetically distinct. 5. Although the role of viruses in aquatic systems is complex and remains insufficiently studied, our survey of the literature indicates that, despite some differences, many of the controls on virioplankton activity and diversity are similar in marine and freshwater environments. [source]

Can taxonomic distinctness assess anthropogenic impacts in inland waters?

FRESHWATER BIOLOGY, Issue 9 2006
A case study from a Mediterranean river basin
Summary 1. It is increasingly recognised that adequate measures of biodiversity should include information on the ,relatedness' of species within ecological assemblages, or the phylogenetic levels at which diversity is expressed. Taxonomic distinctness measures provide a series of indices to achieve this, which are independent of sample size. Taxonomic distinctness has been employed widely in marine systems, where it has been suggested that this index can provide a reliable measure of anthropogenic impact. 2. We tested the behaviour of three related taxonomic distinctiveness indices (Average Taxonomic Distinctness, ,+; Variation in Taxonomic Distinctness, ,+; and Total Taxonomic Distinctness, s,+) in relation to putative levels of anthropogenic impact in inland waters and their potential utility in environmental monitoring, using an extensive data set for aquatic beetles from the south-east of the Iberian Peninsula. 3. Taxonomic distinctness measures were not able to identify human disturbance effects and there were no clear relationships between these new biodiversity measures and the disturbance level recorded at individual localities. Furthermore, the taxonomic distinctness measures used were apparently less sensitive to the effects of anthropogenic impact than other diversity metrics, such as species richness and rarity. 4. We conclude that taxonomic distinctness indices may not always perform as well as other metrics in the assessment of environmental quality. In addition, taxonomic distinctness measure should be interpreted with caution, as their performance and ability to detect anthropogenic disturbance may depend on the phylogenetic structure of sampled taxa within a region, and their evolutionary and ecological history. [source]

Net spinning caddisflies as stream ecosystem engineers: the influence of Hydropsyche on benthic substrate stability

FUNCTIONAL ECOLOGY, Issue 3 2004
B. J. CARDINALE
Summary 1Organisms that physically modify or create habitat (ecosystem engineers) can have a profound influence on community and ecosystem dynamics. 2Here evidence is presented that one of the most abundant and widely distributed lotic insects could act as an ecosystem engineer in streams by increasing the stability of benthic substrates during flooding. 3Natural densities of larval net spinning caddisflies (Hydropsychidae) were established in stream channels that had standardized physical properties. The mobility of three particle sizes were measured during simulated flooding and the fraction of particles eroded compared with that of control streams. 4Larvae increased the initial velocity required to erode sediments by 10,30%. At velocities sufficient to scour 87% of particles from control channels, 57,100% remained stable in channels colonized by larvae. 5Assuming larvae have similar effects in natural streams, caddisflies could be expected to increase the recurrence interval of a substrate scouring flood from 1·67 year to 2·41 year, corresponding to a 17% decrease in the probability of bed scour per year. 6Our study suggests these insects could play an important role in generating the spatial ,refuges' that moderate the resistance of lotic communities to flooding. It is argued that, as has occurred in marine systems, a better understanding of how freshwater organisms engineer their physical environment has much potential to complement our historical focus on the abiotic forces that constrain populations and communities. [source]

Altered kelp (Laminariales) phlorotannins and growth under elevated carbon dioxide and ultraviolet-B treatments can influence associated intertidal food webs

GLOBAL CHANGE BIOLOGY, Issue 8 2007
ANDREW K. SWANSON
Abstract Due to the importance of brown algae, such as kelp (Laminariales, Phaeophyta), within most cool nearshore environments, any direct responses of kelp to multiple global changes could alter the integrity of future coastal marine systems. Fifty-five-day manipulation of carbon dioxide (CO2) and ultraviolet light (UVB) within outdoor sea-tanks, approximating past, present and two predicted future levels, examined the direct influences on Saccharina latissima (=Laminaria saccharina) and Nereocystis luetkeana development and biochemistry, as well as the indirect influences on a marine herbivore (Tegula funebralis; Gastropoda, Mollusca) and on naturally occurring intertidal detritivores. Kelp species displayed variable directional (negative and positive growth) and scale responses to CO2 and UVB manipulations, which was influenced by interactions. Kelp phlorotannin (phenolic) production in blade tissues was induced by elevated UVB levels, and especially enhanced (additively) by elevated CO2, further suggesting that some actively growing kelp species are carbon limited in typical nearshore environments. Negative indirect effects upon detritivore consumers fed CO2 -manipulated kelp blade tissues were detected, however, no statistical relationships existed among UVB-treated tissues, and test herbivores did not distinguish between phlorotannin-altered CO2: UVB-treated kelp blade tissues. Results suggest that past and future conditions differentially benefit these kelp species, which implies a potential for shifts in species abundance and community composition. Higher CO2 conditions can indirectly impede marine decay processes delaying access to recycled trace nutrients, which may be disruptive to the seasonal regrowth of algae and/or higher trophic levels of nearshore ecosystems. [source]

Marine range shifts and species introductions: comparative spread rates and community impacts

GLOBAL ECOLOGY, Issue 3 2010
Cascade J. B. Sorte
ABSTRACT Aim, Shifts in species ranges are a predicted and realized effect of global climate change; however, few studies have addressed the rates and consequence of such shifts, particularly in marine systems. Given ecological similarities between shifting and introduced species, we examined how our understanding of range shifts may be informed by the more established study of non-native species introductions. Location, Marine systems world-wide. Methods, Database and citation searches were used to identify 129 marine species experiencing range shifts and to determine spread rates and impacts on recipient communities. Analyses of spread rates were based on studies for which post-establishment spread was reported in linear distance. The sizes of the effects of community impacts of shifting species were compared with those of functionally similar introduced species having ecologically similar impacts. Results, Our review and meta-analyses revealed that: (1) 75% of the range shifts found through the database search were in the poleward direction, consistent with climate change scenarios, (2) spread rates of range shifts were lower than those of introductions, (3) shifting species spread over an order of magnitude faster in marine than in terrestrial systems, and (4) directions of community effects were largely negative and magnitudes were often similar for shifters and introduced species; however, this comparison was limited by few data for range-shifting species. Main conclusions, Although marine range shifts are likely to proceed more slowly than marine introductions, the community-level effects could be as great, and in the same direction, as those of introduced species. Because it is well-established that introduced species are a primary threat to global biodiversity, it follows that, just like introductions, range shifts have the potential to seriously affect biological systems. In addition, given that ranges shift faster in marine than terrestrial environments, marine communities might be affected faster than terrestrial ones as species shift with climate change. Regardless of habitat, consideration of range shifts in the context of invasion biology can improve our understanding of what to expect from climate change-driven shifts as well as provide tools for formal assessment of risks to community structure and function. [source]

Small fish, big fish, red fish, blue fish: size-biased extinction risk of the world's freshwater and marine fishes

GLOBAL ECOLOGY, Issue 6 2007
Julian D. Olden
ABSTRACT Aim, In light of the current biodiversity crisis, there is a need to identify and protect species at greatest risk of extinction. Ecological theory and global-scale analyses of bird and mammal faunas suggest that small-bodied species are less vulnerable to extinction, yet this hypothesis remains untested for the largest group of vertebrates, fish. Here, we compare body-size distributions of freshwater and marine fishes under different levels of global extinction risk (i.e. listed as vulnerable, endangered or critically endangered according to the IUCN Red List of Threatened Species) from different major sources of threat (habitat loss/degradation, human harvesting, invasive species and pollution). Location, Global, freshwater and marine. Methods, We collated maximum body length data for 22,800 freshwater and marine fishes and compared body-size frequency distributions after controlling for phylogeny. Results, We found that large-bodied marine fishes are under greater threat of global extinction, whereas both small- and large-bodied freshwater species are more likely to be at risk. Our results support the notion that commercial fishing activities disproportionately threaten large-bodied marine and freshwater species, whereas habitat degradation and loss threaten smaller-bodied marine fishes. Main conclusions, Our study provides compelling evidence that global fish extinction risk does not universally scale with body size. Given the central role of body size for trophic position and the functioning of food webs, human activities may have strikingly different effects on community organization and food web structure in freshwater and marine systems. [source]

Dynamics of mutualist populations that are demographically open

JOURNAL OF ANIMAL ECOLOGY, Issue 6 2006
ANDREW R. THOMPSON
Summary 1Few theoretical studies have examined the impact of immigration and emigration on mutualist population dynamics, but a recent empirical study (A.R. Thompson Oecologia, 143, 61,69) on mutualistic fish and shrimp showed that immigration can prevent population collapse, and that intraspecific competition for a mutualistic partner can curb population expansion. To understand in a theoretical context the implications of these results, and to assess their generality, we present a two-species model that accounts explicitly for immigration and emigration, as well as distinguishing the impacts of mutualism on birth rates, death rates and habitat acquisition. 2The model confirms that immigration can stabilize mutualistic populations, and predicts that high immigration, along with enhanced reproduction and/or reduced mortality through mutualism, can cause population sizes to increase until habitat availability curbs further expansion. 3We explore in detail the effects of different forms of habitat limitation on mutualistic populations. Habitat availability commonly limits the density of both populations if mutualists acquire shelter independently. If a mutualist depends on a partner for habitat, densities of that mutualist are capped by the amount of space provided by that partner. The density of the shelter-provider is limited by the environment. 4If a mutualism solely augments reproduction, and most locally produced individuals leave the focal patch, then the mutualism will have a minimal effect on local dynamics. If the mutualism operates by reducing rates of death or enhancing habitat availability, and there is at least some immigration, then mutualism will affect local dynamics. This finding may be particularly relevant in marine systems, where there is high variability (among species and locations) in the extent to which progeny disperse from natal locations. 5Overall, our results demonstrate that the consequences of immigration and emigration for the dynamics of mutualists depend strongly on which demographic rate is influenced by mutualism. 6By relating our model to a variety of terrestrial and aquatic systems, we provide a general framework to guide future empirical studies of the dynamics of mutualistic populations. [source]

Current issues with fish and fisheries: editor's overview and introduction

JOURNAL OF APPLIED ECOLOGY, Issue 2 2003
S. J. Ormerod
Summary 1.,By any measure, fishes are among the world's most important natural resources. Annual exploitation from wild populations exceeds 90 million tonnes, and fish supply over 15% of global protein needs as part of total annual trade exceeding $US 55 billion. Additionally, with over 25 000 known species, the biodiversity and ecological roles of fishes are being increasingly recognised in aquatic conservation, ecosystem management, restoration and aquatic environmental regulation. 2.,At the same time, substantial management problems now affect the production, exploitable stocks, global diversity, trophic structure, habitat quality and local composition of fish communities. 3.,In marine systems, key issues include the direct effects of exploitation on fish, habitats and other organisms, while habitat or water quality problems arise also from the atmospheric, terrestrial and coastal environments to which marine systems are linked. In freshwaters, flow regulation and obstruction by dams, fragmentation, catchment management, pollution, habitat alterations, exotic fish introductions and nursery-reared fish are widespread issues. 4.,Management responses to the problems of fish and fisheries include aquatic reserves in both marine and freshwater habitats, and their effectiveness is now being evaluated. Policies on marine exploitation increasingly emphasise fishes as integral components of aquatic ecosystems rather than individually exploitable stocks, but the rationalisation of fishing pressures presents many challenges. In Europe, North America and elsewhere, policies on freshwaters encourage habitat protection, integrated watershed management and restoration, but pressures on water resources will cause continued change. All these management approaches require development and evaluation, and will benefit from a perspective of ecological understanding with ecologists fully involved. 5.,Synthesis and applications. Although making a small contribution to the Journal of Applied Ecology in the past, leading work on aquatic problems and fish-related themes appear increasingly in this and other mainstream ecology journals. As this special profile of five papers shows, significant contributions arise on diverse issues that here include the benefit of aquatic reserves, river restoration for fish, the accumulation of contaminants, interactions with predators, and the fitness of salmonids from nurseries. This overview outlines the current context in which papers on the applied ecology of fish and fisheries are emerging, and it identifies scope for further contributions. [source]

The uptake of applied ecology

JOURNAL OF APPLIED ECOLOGY, Issue 1 2002
S. J. Ormerod
Summary 1We asked 229 authors who have published recently in the Journal of Applied Ecology (1999,2001) whether their papers made management or policy recommendations and whether they had evidence of consequent uptake. 2A total of 108 respondents working in the UK (34%), Europe (30%), the Americas (12%), Australasia (11%), Asia (7%) and Africa (6%) reported on 110 papers. They represented agro-ecosystems (35%), temperate forests or woodlands (16%), savanna, grass or arid lands (11%), rivers or wetlands (10%), estuaries or marine systems (7%) and tropical forests (5%). The major organisms were invertebrates (27%), birds (24%), mammals (21%) and higher plants (21%). Topics apparently under-represented in recent coverage include ecosystem science, urban areas, soils, mountain systems, fish, amphibians and lower organisms such as algae. 3Almost all papers (99%) carried recommendations and for 57% there was evidence of uptake in the broad categories of ,environmental management or models', ,information, training and education' and ,monitoring and assessment'. Most uptake involved large geographical scales through habitat or species management plans (32% of cases), effects on reserve design or designation (6%), and effects on agri-environmental policy (5%). The development of further research (11%), the communication of methods to other ecologists (9%), the dissemination of recommendations to practitioners or agencies (7%), and uptake in training or education (5%) were important uses of information. 4Prestige from publication in the Journal of Applied Ecology aided several authors in convincing end-users of research value. User involvement in research as participants or funders was widespread (> 42% of papers), a fact which almost certainly promotes uptake along with the parallel dissemination of management messages. We view applied issues as an important interface between end-users and ecologists of value to ,both' communities but suggest that improved communication will further benefit the sponsorship and application of ecological science. 5The major reason offered for lack of uptake was that it was still too soon after publication (21% of respondents). Costs, difficulty of implementation, the scale of the problem, and ,challenges to existing thinking' each figured in more than one response. 6For some respondents, papers were led by curiosity rather than the need for direct application. Several authors published in the Journal to share ideas internationally, or said that recommendations were general, conceptual or long-term rather than specific. The editors of the Journal of Applied Ecology recognize the seminal importance of contributions that affect policy incrementally and conceptually as much as those with specific application. 7These data provide evidence that ecological science is aiding environmental management and policy across a wide range of regions, ecosystems and types of organisms; rather than merely detecting problems, applied ecology is offering solutions both directly and more diffusely through conceptual advance. We invite the user community to offer their own perspectives about the value of research-led publications such as this Journal, about how links between researchers and users might be strengthened, and about how the uptake of applied ecology might be further advanced. [source]

Covalently linked immunomagnetic separation/adenosine triphosphate technique (Cov-IMS/ATP) enables rapid, in-field detection and quantification of Escherichia coli and Enterococcus spp. in freshwater and marine environments

JOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2010
C.M. Lee
Abstract Aims:, Developing a rapid method for detection of faecal pollution is among the critical goals set forth by the Environmental Protection Agency in its revision of water quality criteria. The purpose of this study is to devise and test covalently linked antibody,bead complexes for faecal indicator bacteria (FIB), specifically Escherichia coli or Enterococcus spp., in measuring water quality in freshwater and marine systems. Methods and Results:, Covalently linked complexes were 58,89% more robust than antibody,bead complexes used in previous studies. Freshwater and marine water samples analysed using covalently linked immunomagnetic separation/adenosine triphosphate quantification technique (Cov-IMS/ATP) and culture-based methods yielded good correlations for E. coli (R = 0·87) and Enterococcus spp. (R = 0·94), with method detection limits below EPA recreational water quality health standards for single standard exceedances (E. coli, 38 cells per 100 ml; Enterococcus spp. , 25 cells per 100 ml). Cov-IMS/ATP correctly classified 87% of E. coli and 94% of Enterococcus spp. samples based on these water quality standards. Cov-IMS/ATP was also used as a field method to rapidly distinguish differential loading of E. coli between two stream channels to their confluence. Conclusions:, Cov-IMS/ATP is a robust, in-field detection method for determining water quality of both fresh and marine water systems as well as differential loading of FIB from two converging channels. Significance and Impact of the Study:, To our knowledge, this is the first work to present a viable rapid, in-field assay for measuring FIB concentrations in marine water environments. Cov-IMS/ATP is a potential alternative detection method, particularly in areas with limited laboratory support and resources, because of its increased economy and portability. [source]

Facilitation research in marine systems: state of the art, emerging patterns and insights for future developments

JOURNAL OF ECOLOGY, Issue 6 2009
Fabio Bulleri
Summary 1. Positive species interactions are increasingly recognized as important drivers of community structure and ecosystem functioning. Although the literature on facilitative interactions in terrestrial environments has been reviewed and emerging patterns have been synthesized, comparable attempts are lacking for the marine realm. 2. By means of a quantitative survey of the literature, I provide a critical summary of current knowledge on positive species interactions in marine environments. In particular, I (i) assess how marine facilitation research compares to that carried out in terrestrial environments in terms of focus and philosophical approach; (ii) illustrate the mechanisms by which facilitation takes place in different habitats; (iii) assess whether benefactor and beneficiary species are more likely to belong to the same or to a different trophic level; and (iv) provide examples of how including facilitation into ecological theory might advance our understanding of the mechanisms that regulate ecosystem functioning. 3. Except for some studies in intertidal habitats, few studies in marine environments have been framed within mainstream facilitation theory (e.g. the Stress Gradient Hypothesis) and research does not seem to be organized in a self-contained theme. Amelioration of physical conditions appears to be the most common mechanism of facilitation in intertidal habitats, whilst associational defence predominates in the subtidal. 4. In contrast to the terrestrial literature, dominated by plant,plant interactions, marine benefactors and beneficiary species often belong to different trophic levels. This might imply little overlapping of resource niches or a differential response to environmental conditions or consumer pressure, with implications for the persistence of facilitative effects at the extreme ends of stress gradients. 5. Recent research shows that facilitation can enhance temporal variability and invasibility of marine communities and emphasizes the central role of positive species interactions in regulating the functioning of natural ecosystems. 6.Synthesis. Studies encompassing a wide variety of life histories and environmental conditions are central to achieving a unified facilitation theory. Research in marine environments can provide new insights into the mechanisms underlying variations in the strength and direction of species interactions, but this will require greater awareness and consideration of facilitation. [source]

Ecological speciation in marine v. freshwater fishes

JOURNAL OF FISH BIOLOGY, Issue 5 2009
O. Puebla
Absolute barriers to dispersal are not common in marine systems, and the prevalence of planktonic larvae in marine taxa provides potential for gene flow across large geographic distances. These observations raise the fundamental question in marine evolutionary biology as to whether geographic and oceanographic barriers alone can account for the high levels of species diversity observed in marine environments such as coral reefs, or whether marine speciation also operates in the presence of gene flow between diverging populations. In this respect, the ecological hypothesis of speciation, in which reproductive isolation results from divergent or disruptive natural selection, is of particular interest because it may operate in the presence of gene flow. Although important insights into the process of ecological speciation in aquatic environments have been provided by the study of freshwater fishes, comparatively little is known about the possibility of ecological speciation in marine teleosts. In this study, the evidence consistent with different aspects of the ecological hypothesis of speciation is evaluated in marine fishes. Molecular approaches have played a critical role in the development of speciation hypotheses in marine fishes, with a role of ecology suggested by the occurrence of sister clades separated by ecological factors, rapid cladogenesis or the persistence of genetically and ecologically differentiated species in the presence of gene flow. Yet, ecological speciation research in marine fishes is still largely at an exploratory stage. Cases where the major ingredients of ecological speciation, namely a source of natural divergent or disruptive selection, a mechanism of reproductive isolation and a link between the two have been explicitly documented are few. Even in these cases, specific predictions of the ecological hypothesis of speciation remain largely untested. Recent developments in the study of freshwater fishes illustrate the potential for molecular approaches to address specific questions related to the ecological hypothesis of speciation such as the nature of the genes underlying key ecological traits, the magnitude of their effect on phenotype and the mechanisms underlying their differential expression in different ecological contexts. The potential provided by molecular studies is fully realized when they are complemented with alternative (e.g. ecological, theoretical) approaches. [source]

Spatial and temporal scales of adaptive divergence in marine fishes and the implications for conservation

JOURNAL OF FISH BIOLOGY, Issue 2006
D. O. Conover
Knowledge of geographic and temporal scales of adaptive genetic variation is crucial to species conservation, yet understanding of these phenomena, particularly in marine systems, is scant. Until recently, the belief has been that because most marine species have highly dispersive or mobile life stages, local adaptation could occur only on broad geographic scales. This view is supported by comparatively low levels of genetic variation among populations as detected by neutral markers. Similarly, the time scale of adaptive divergence has also been assumed to be very long, requiring thousands of generations. Recent studies of a variety of species have challenged these beliefs. First, there is strong evidence of geographically structured local adaptation in physiological and morphological traits. Second, the proportion of quantitative trait variation at the among-population level (QST) is much higher than it is for neutral markers (FST) and these two metrics of genetic variation are poorly correlated. Third, evidence that selection is a potent evolutionary force capable of sustaining adaptive divergence on contemporary time scales is summarized. The differing spatial and temporal scales of adaptive v. neutral genetic divergence call for a new paradigm in thinking about the relationship between phenogeography (the geography of phenotypic variation) and phylogeography (the geography of lineages) in marine species. The idea that contemporary selective processes can cause fine-scale spatial and temporal divergence underscores the need for a new emphasis on Darwinian fishery science. [source]

Understanding fish habitat ecology to achieve conservation,

JOURNAL OF FISH BIOLOGY, Issue 2005
J. C. Rice
Habitat science can provide the unifying concepts to bring together ecological studies of physiological tolerances, predator avoidance, foraging and feeding, reproduction and life histories. Its unifying role is built on two assumptions, imported from terrestrial habitat science and not always stated explicitly: that competition is present interspecifically and intraspecifically under at least some conditions, and that habitat features have some persistence and predictability in space and time. Consistent with its central conceptual position in ecology, habitat science has contributed importantly to scientific advice on pollution, coastal zone management and many other areas of environmental quality, although it has been largely divorced from developments in fish populations dynamics done in support of fisheries management. Commitments by most management agencies to apply an integrated, ecosystem approach to management of human activities in marine systems, poses new challenges to marine science advisors to management. Integrated management and ecosystem approaches both inherently require spatial thinking and spatial tools, making habitat science a particularly relevant advisory framework, particularly because of the unifying role of habitat in ecology. The basic mechanisms behind ocean biological dynamics, productivity, concentration and retention, however, present much weaker opportunities for competition and less persistence and predictability, weakening the foundations of theory and concepts behind current habitat science. The paper highlights the new types of thinking about ,habitat' that will be required, if habitat science is to meet the advisory needs of the new approaches to management. [source]