Governance Profiles and the Management of the Uses of Large Marine Ecosystems

Interest in the management of the environment and its resources on an ecosystem basis has been increasing in both terrestrial and marine contexts. The emergence of the concept of large marine ecosystems (LMEs) is one important example of this development. LMEs have been examined through five linked modules: (1) productivity of the ecosystem; (2) fish and fisheries; (3) pollution and ecosystem health; (4) socioeconomic conditions; and (5) governance. The first three focus on natural systems, while the last two concentrate on human interactions with those systems. To date the first three have received the greatest attention but as attention has turned to development and implementation of management strategies, greater consideration has being given to the human dimension of LMEs represented by the latter two modules. This article focuses on governance, a matter that is of fundamental importance because it shapes the pattern of human use of the natural environment. Efforts to promote ecosystem-based management occur within different governance frameworks; these frameworks and their associated dynamics must be understood in the same fashion that the structure and interplay of the elements of the natural ecosystem need to be comprehended. Just as natural science employs baseline studies to gauge change over time, this paper asserts the need for similar studies relevant to governance aspects of ecosystem use. After identifying and describing the roles of three major and generic governance institutions, we suggest the development in each LME of a governance profile that outlines and analyzes the existing governance framework. Moreover, we propose to consider governance change over time to assess whether such shifts represent movement in the direction of greater ecosystem focus.     

Principles for Assessing the Reliability of Sediment Quality Guidelines

Over the last few years, many different types of sediment quality guidelines have been derived, and a debate has begun on how best to evaluate the predictive reliability of these guidelines. The reliability of sediment quality guidelines has important consequences for selection of specific guidelines for use, sampling designs, regulatory decision frameworks, and the extent to which biological testing is required to make decisions about dredging and cleanup actions. However, the authors of these studies are not all using the same terminology, the same definitions of errors and error rates, or the same methods of calculation. Definitions and general principles for determining the reliability of SQGs are proposed, to promote a common basis for discussion and comparison of the various SQGs available for use. Significant issues with current approaches to estimating reliability are also discussed.     

Formation of Siderite in Microbial Microcosms Derived from a Marine Sediment

Abstract

Exceptionally well-preserved fossils are frequently encased by carbonate concretions. The initial steps of their formation in marine and freshwater sediments are induced by microbial activity. The role of the involved microbial communities, however, is not well understood. In this study, siderite (FeCO₃) formation in microbial microcosms is observed, with various fatty acyl compounds (lipids, surfactants) as substrates and Wadden Sea sediment samples as inocula. In actively growing microcosms, sulfate-reducing bacteria (the genus Desulfofrigus in particular) dominate the microbial community and submicroscopic siderite precipitates on bacterial cell surfaces were identified. We suggest that these biologically induced mineralization processes may, in the natural environment, initiate the formation of large concretions under suboxic conditions in coastal sediments.     

Nutritional Behavior,Morphogenesis Cycle and Sediment Consolidation Capabilities of the Calcareous Bacteria Derived from Coastal Marine Sediments

Samples from stones and sediments of a coastal site in the Bay of Bengal (Indian Ocean) yielded as many as 39 new bacterial isolates capable of precipitating calcium carbonate (CaCO₃). Molecular identification revealed that these bacteria belonged predominantly to the phyla Firmicutes and Proteobacteria. Culture studies showed that nitrogen sources controlled the metabolic pathway of crystal precipitation, which was restricted to three reaction pathways, namely the deamination of amino acids, ureolytic nitrate reduction and dissimilatory nitrate reduction. The sequence of crystal morphogenesis clearly showed that bacterial precipitation of CaCO₃ led to predominantly spherical structures with time. The present investigation provides the first demonstration of the bacterial contribution and mechanisms involved in the calcareous consolidation of stones and sediments by bacteria in the marine environment.     

Rationale and Procedures for Using the Tissue-Residue Approach for Toxicity Assessment and Determination of Tissue,Water, and Sediment Quality Guidelines for Aquatic Organisms

This article describes a set of procedures for developing tissue, water, and sediment quality guidelines for the protection of aquatic life by using the tissue-residue approach (TRA) for toxicity assessment. The TRA, which includes aspects of the Critical Body Residue (CBR) approach, associates tissue concentrations of chemicals with adverse biological effects in a dose-response fashion that can be used to determine CBRs. These CBRs can then be used to develop tissue quality guidelines (TQGs), which may be translated into water or sediment guidelines with bioaccumulation factors. Not all toxicants are amenable to this type of analysis; however, some appear to exhibit relatively consistent results that can likely be applied in a regulatory framework. By examining tissue residues, variations in toxicokinetics (temporal aspects of accumulation, biotransformation, and internal distribution) are greatly reduced allowing a greater focus on toxicodynamics (action and potency) of the toxicants. The strongest feature of this approach is causality; hence, guidelines based on tissue concentrations are based on data demonstrating a causal relationship between the acquired dose and the biological effect. Because the TRA has utility for assessing the toxicity of contaminant mixtures, an approach is presented here using toxic unit values that can be used to assess the likelihood of observing toxic effects based on tissue residues.     

Annual Pattern of Denitrification and Nitrate Ammonification in Estuarine Sediment

The seasonal variation and depth distribution of the capacity for denitrification and dissimilatory NO₃⁻ reduction to NH₄⁺ (NO₃⁻ ammonification) were studied in the upper 4 cm of the sediment of Norsminde Fjord estuary, Denmark. A combination of C₂H₂ inhibition and ¹⁵N isotope techniques was used in intact sediment cores in short-term incubations (maximum, 4 h). The denitrification capacity exhibited two maxima, one in the spring and one in the fall, whereas the capacity for NO₃⁻ ammonification was maximal in the late summer, when sediments were progressively reduced. The denitrification capacity was always highest in the uppermost 1 cm of the sediment and declined with depth. The NO₃⁻ ammonification was usually higher with depth, but the maximum activity in late summer was observed within the upper 1 cm. The capacity for NO₃⁻ incorporation into organic material was investigated on two occasions in intact sediment cores and accounted for less than 5% of the total NO₃⁻ reduction. Denitrification accounted for between 13 and 51% of the total NO₃⁻ reduction, and NH₄⁺ production accounted for between 4 and 21%, depending on initial rates during the time courses. Changes of the rates during the incubation were observed in the late summer, which reflected synthesis of denitrifying enzymes. This time lag was eliminated in experiments with mixed sediment because of preincubation with NO₃⁻ and alterations of the near-environmental conditions. The initial rates obtained in intact sediment cores therefore reflect the preexisting enzyme content of the sediment.     

Demographic Aspects of Marine, Soft Sediment Patch Dynamics

A generalized framework is presented which employs a demographicperspectivec (population vital rates, measures of populationperformance) of infaunal patch dynamics in order to understandpopulation- and community-level successional processes in soft-sedimenthabitats. The model emphasizes the importance of demographicresponses of component species following disturbance and howthey vary as a function of the successional state within eachpatch. These characteristics provide a currency for assessingthe effects of the disturbance on the overall population dynamicsin a given habitat. Simple demographic simulations indicatethe importance of seasonality in affecting the response of speciesto disturbance and the relative contributions of adult and larvalcolonization in affecting population dynamics. Further developmentof this demographic framework is presently constrained by ageneral lack of field data necessary to evaluate the demographyof soft-sediment organisms.     

Research Commentary: Association of Zoonotic Pathogens with Fresh, Estuarine, and Marine Macroaggregates

Aquatic macroaggregates (flocs ≥0.5 mm) provide an important mechanism for vertical flux of nutrients and organic matter in aquatic ecosystems, yet their role in the transport and fate of zoonotic pathogens is largely unknown. Terrestrial pathogens that enter coastal waters through contaminated freshwater runoff may be especially prone to flocculation due to fluid dynamics and electrochemical changes that occur where fresh and marine waters mix. In this study, laboratory experiments were conducted to evaluate whether zoonotic pathogens (Cryptosporidium, Giardia, Salmonella) and a virus surrogate (PP7) are associated with aquatic macroaggregates and whether pathogen aggregation is enhanced in saline waters. Targeted microorganisms showed increased association with macroaggregates in estuarine and marine waters, as compared with an ultrapure water control and natural freshwater. Enrichment factor estimations demonstrated that pathogens are 2–4 orders of magnitude more concentrated in aggregates than in the estuarine and marine water surrounding the aggregates. Pathogen incorporation into aquatic macroaggregates may influence their transmission to susceptible hosts through settling and subsequent accumulation in zones where aggregation is greatest, as well as via enhanced uptake by invertebrates that serve as prey for marine animals or as seafood for humans.     

Methylmercury in Marine Ecosystems: Spatial Patterns and Processes of Production,Bioaccumulation, and Biomagnification

The spatial variation of MeHg production, bioaccumulation, and biomagnification in marine food webs is poorly characterized but critical to understanding the links between sources and higher trophic levels, such as fish that are ultimately vectors of human and wildlife exposure. This article discusses both large and local scale processes controlling Hg supply, methylation, bioaccumulation, and transfer in marine ecosystems. While global estimates of Hg supply suggest important open ocean reservoirs of MeHg, only coastal processes and food webs are known sources of MeHg production, bioaccumulation, and bioadvection. The patterns observed to date suggest that not all sources and biotic receptors are spatially linked, and that physical and ecological processes are important in transferring MeHg from source regions to bioaccumulation in marine food webs and from lower to higher trophic levels.     

Global Invasions of Marine and Estuarine Habitats by Non-Indigenous Species: Mechanisms, Extent, and Consequences

Non-indigenous species (NIS) are increasingly conspicuous inmarine and estuarine habitats throughout the world, as the number,variety, and effects of these species continue to accrue. Mostof these NIS invasions result from anthropogenic dispersal.Although the relative importance of different dispersal mechanismsvaries both spatially and temporally, the global movement ofballast water by ships appears to be the largest single vectorfor NIS transfer today, andmany recent invasions have resultedfrom this transfer. The rate of new invasions may have increasedin recent decades, perhaps due to changes in ballast water transport.Estuaries have been especially common sites of invasions, accumulatingfrom tens to hundreds of NIS per estuary that include most majortaxonomic and trophic groups. We now know of approximately 400NIS along the Pacific, Atlantic and Gulf coasts of the U.S.,and hundreds of marine and estuarine NIS are reported from otherregions of the world. Although available information about invasionsis limited to a few regions and underestimates the actual numberof NIS invasions, there are apparent differences in the frequencyof NIS among sites. Mechanisms responsible for observed patternsamong sites likely include variation in supply of NIS, and perhapsvariation in properties of recipient or donor communities,butthe role of these mechanisms has not been tested. Although ourpresent knowledge about the extent, patterns and mechanismsof marine invasions is still in its infancy, it is clear thatNIS are a significant force of change in marine and especiallyestuarine communities globally. Taxonomically diverse NIS arehaving significant effects on many, if not most, estuaries thatfundamentally alter population, community, and ecosystems processes.The impacts of most NIS remain unknown, and the predictabilityof their direct and indirect effects remains uncertain. Nonetheless,based upon the documented extent of NIS invasions and scopeof then effects, studies of marine communities that do not includeNIS are increasingly incomplete     

Effect of Estuarine Sediment pH and Oxidation-Reduction Potential on Microbial Hydrocarbon Degradation

Microbial mineralization rates of two petroleum hydrocarbons, as affected by pH and oxidation-reduction potential, were determined in a Barataria Bay, Louisiana, sediment using ¹⁴C-labeled hydrocarbons. Hydrocarbon mineralization rates were inferred from the activity of respired ¹⁴CO₂. Sediment pH and oxidation-reduction potential were important factors in governing the population of hydrocarbon-degrading microorganisms in the sediment and subsequent mineralization rates. Highest mineralization rates occurred at pH 8.0, and the lowest occurred at pH 5.0. At all pH levels mineralization decreased with decreasing oxidation-reduction potential (i.e., increasing sediment anaerobiosis). Generally, mineralization rates for octadecane were greater than those for naphthalene. Aerobic microorganisms in the oxidized sediment were more capable of degrading hydrocarbons than anaerobic microorganisms in reduced sediment of the same pH.     

Characteristics of Marine Aggregates in Shallow-water Ecosystems: Implications for Disease Ecology

Marine aggregates were evaluated for their potential role in the ecology of aquatic pathogens using underwater video surveys coupled with direct collection of aggregates in modified settling cones. Six locations, two each in New York, Connecticut, and Massachusetts, were surveyed over 8 months to explore differences in the characteristics of aggregates found in habitats populated by clams (Mercenaria mercenaria) and oysters (Crassostrea virginica). Microaggregate (<500 μm) concentrations were always greater than macroaggregate (>500 μm) concentrations, but peak concentrations of macroaggregates and microaggregates, mean size of particles, and volume fraction of aggregated material varied among the six shallow-water habitats. Concentrations (colony-forming units per ml) of total heterotrophic bacteria (THB) and total mesophilic pathogenic bacteria (MPB) from samples of aggregates were significantly different among the four locations bordering Long Island Sound (LIS). The highest concentrations and enrichment factors in aggregates were observed in August for THB and in June for MPB. Significant correlations were detected for salinity and the concentrations and enrichment factors of THB in aggregates and for the concentrations and percentages of MPB in seawater samples. Significant correlations were also detected for temperature and the concentrations of MPB in aggregates and the enrichment factors for THB and MPB (marginal significance). Bacterial species identified in association with aggregates included: Vibrio cholerea, V. parahaemolyticus, V. vulnificus, V. alginolyticus, Aeromonas hydrophila, Pseudomonas aeruginosa, Escherichia coli, and Mycobacteria sp. These results have important implications for the way in which aquatic pathogens are collected, quantified, and monitored for risk-based surveillance in shallow-water ecosystems.     

Spatial Variation in Soil Properties among North American Ecosystems and Guidelines for Sampling Designs

Soils are highly variable at many spatial scales, which makes designing studies to accurately estimate the mean value of soil properties across space challenging. The spatial correlation structure is critical to develop robust sampling strategies (e.g., sample size and sample spacing). Current guidelines for designing studies recommend conducting preliminary investigation(s) to characterize this structure, but are rarely followed and sampling designs are often defined by logistics rather than quantitative considerations. The spatial variability of soils was assessed across ∼1 ha at 60 sites. Sites were chosen to represent key US ecosystems as part of a scaling strategy deployed by the National Ecological Observatory Network. We measured soil temperature (T_s) and water content (SWC) because these properties mediate biological/biogeochemical processes below- and above-ground, and quantified spatial variability using semivariograms to estimate spatial correlation. We developed quantitative guidelines to inform sample size and sample spacing for future soil studies, e.g., 20 samples were sufficient to measure T_s to within 10% of the mean with 90% confidence at every temperate and sub-tropical site during the growing season, whereas an order of magnitude more samples were needed to meet this accuracy at some high-latitude sites. SWC was significantly more variable than T_s at most sites, resulting in at least 10× more SWC samples needed to meet the same accuracy requirement. Previous studies investigated the relationship between the mean and variability (i.e., sill) of SWC across space at individual sites across time and have often (but not always) observed the variance or standard deviation peaking at intermediate values of SWC and decreasing at low and high SWC. Finally, we quantified how far apart samples must be spaced to be statistically independent. Semivariance structures from 10 of the 12-dominant soil orders across the US were estimated, advancing our continental-scale understanding of soil behavior.     

Biphasic Behavior of Anammox Regulated by Nitrite and Nitrate in an Estuarine Sediment

The production of N₂ gas via anammox was investigated in sediment slurries at in situ NO₂⁻ concentrations in the presence and absence of NO₃⁻. With single enrichment above 10 μM ¹⁴NO₂⁻ or ¹⁴NO₃⁻ and ¹⁵NH₄⁺, anammox activity was always linear (P < 0.05), in agreement with previous findings. In contrast, anammox exhibited a range of activity below 10 μM NO₂⁻ or NO₃⁻, including an elevated response at lower concentrations. With 100 μM NO₃⁻, no significant transient accumulation of NO₂⁻ could be measured, and the starting concentration of NO₂⁻ could therefore be regulated. With dual enrichment (1 to 20 μM NO₂⁻ plus 100 μM NO₃⁻), there was a pronounced nonlinear response in anammox activity. Maximal activity occurred between 2 and 5 μM NO₂⁻, but the amplitude of this peak varied across the study (November 2003 to June 2004). Anammox accounted for as much as 82% of the NO₂⁻ added at 1 μM in November 2003 but only for 15% in May 2004 and for 26 and 5% of the NO₂⁻ added at 5 μM for these two months, respectively. Decreasing the concentration of NO₃⁻ but holding NO₂⁻ at 5 μM decreased the significance of anammox as a sink for NO₂⁻. The behavior of anammox was explored by use of a simple anammox-denitrification model, and the concept of a biphasic system for anammox in estuarine sediments is proposed. Overall, anammox is likely to be regulated by the availability of NO₃⁻ and NO₂⁻ and the relative size or activity of the anammox population.     

Water Quality of Effluent-dominated Ecosystems: Ecotoxicological, Hydrological, and Management Considerations

In arid and semi-arid regions of the southwestern United States and other parts of the world, flows of historically ephemeral streams are now perennially dominated by municipal and/or industrial effluent discharges, particularly in urbanized watersheds. Because effluent-dominated and dependent water bodies have previously received limited scientific study, we reviewed select contemporary topics associated with water quality of ephemeral streams receiving effluent flows. Our findings indicate that these ecosystems present numerous challenges to aquatic scientists and water resources managers, including: 1) appropriate ecosystems or upstream conditions used reference sites in biomonitoring are difficult to locate or do not exist; 2) water quality criteria, particularly for metals, are dramatically influenced by unique site-specific stream and land use conditions; 3) effluent-dominated streams represent worse-case scenarios for evaluating and predicting aquatic responses to emerging contaminants (e.g., pharmaceuticals and personal care products); 4) low-flow and drought conditions often preclude effective biomonitoring and water quality interpretation, or skew ambient assessment results; 5) chemical-physical water quality parameters (e.g., dissolved oxygen, conductivity, temperature) are dramatically altered by effluent and stormwater characteristics; and 6) beneficial reuse of reclaimed effluent waters potentially conflict with sustainability of ecological integrity. Subsequently, we recommend several water quality research priorities for effluentdominated water bodies.     

Marine Ecosystems as Complex Adaptive Systems: Emergent Patterns,Critical Transitions,and Public Goods

Complex adaptive systems provide a unified framework for explaining ecosystem phenomena. In the past 20 years, complex adaptive systems have been sharpened from an abstract concept into a series of tools that can be used to solve concrete problems. These advances have been led by the development of new techniques for coupling ecological and evolutionary dynamics, for integrating dynamics across multiple scales of organization, and for using data to infer the complex interactions among different components of ecological systems. Focusing on the development and usage of these new methods, we discuss how they have led to an improved understanding of three universal features of complex adaptive systems, emergent patterns; tipping points and critical phenomena; and cooperative behavior. We restrict our attention primarily to marine ecosystems, which provide numerous successful examples of the application of complex adaptive systems. Many of these are currently undergoing dramatic changes due to anthropogenic perturbations, and we take the opportunity to discuss how complex adaptive systems can be used to improve the management of public goods and to better preserve critical ecosystem services.