Future Anthropogenic Change Research Articles

Annual and decadal surveys of molluscs on intertidal platform reefs in a warming marine environment in the southeastern Indian Ocean provide a baseline for monitoring for future environmental changes

ABSTRACT Few data sets are available to evaluate short- and long-term perturbations and impacts of increasing anthropogenic stresses and a warming marine environment in coastal regions near cities. The Perth, Western Australia shoreline has extensive, depauperate sandy beaches interrupted by small, biodiverse intertidal reef platforms. We present transect data on mollusc diversity and density on three Perth platforms recorded from 1983 to 1987, and compare it to 2007 and 2021 to analyse assemblage modifications in response to increased anthropogenic pressures. NMDS multivariate analysis showed a consistent drift in assemblage composition in 2007 and 2021, but this is was not statistically significant from the 1980s baseline (PERMANOVA, P = 0.336). There was no significant long-term decline (or increase) in molluscan species richness. Most species were uncommon but eight were recorded on at least 20 of the 21 surveys. The endemic Western Australian mussel Brachidontes ustulatus (Lamarck, 1819) accounted for 71.8% of all individuals. Total mollusc density varied primarily with changes in B. ustulatus. Tropical species were a minor component of the molluscs that did not change in diversity with warming temperatures. These data provide a long-term baseline for monitoring future anthropogenic changes.

Habitat specialization predicts demographic response and vulnerability of floodplain birds in Amazonia.

The annual flooding cycle of Amazonian rivers sustains the largest floodplains on Earth, which harbour a unique bird community. Recent studies suggest that habitat specialization drove different patterns of population structure and gene flow in floodplain birds. However, the lack of a direct estimate of habitat affinity prevents a proper test of its effects on population histories. In this work, we used occurrence data, satellite images and genomic data (ultra-conserved elements) from 24 bird species specialized on a variety of seasonally flooded environments to classify habitat affinities and test its influence on evolutionary histories of Amazonian floodplain birds. We demonstrate that birds with higher specialization in river islands and dynamic environments have gone through more recent demographic expansion and currently have less genetic diversity than floodplain generalist birds. Our results indicate that there is an intrinsic relationship between habitat affinity and environmental dynamics, influencing patterns of population structure, demographic history and genetic diversity. Within the floodplains, historical landscape changes have had more severe impacts on island specialists, making them more vulnerable to current and future anthropogenic changes, as those imposed by hydroelectric dams in the Amazon Basin.

Forest figures of the past (and present): Consequences on the future of settling with/in forests of the Garhwal Himalayas, India

This research unfolds the notion of ‘settling with/in forests,’ shaped by the dynamic environmental and socio-political interactions in India’s Garhwal Himalayas. Garhwal’s forests perform diverse ecosystem functions that characterise the regional landscape. Settling with/in forests is fundamental to Himalayan communities as, directly and/or indirectly, forests structure the ecology, livelihoods, settlements, and seasonal mobilities across the mountainous landscape. Today, Garhwal’s forests are endangered by the cascading impacts of global warming, increasing urbanisation, natural disasters, and extensive infrastructure construction. Using a “thick description” approach, the research seeks to examine the intertwined layers of forests, local habitats, practices, and institutions, provide insight into the region’s unique environmental history, and identify the challenges associated with settling with/ in forests. The research combines fieldwork, archival materials, and interpretive mapping to examine a case study in the Garhwal Himalayas.The findings highlight the conflicts and coexistence of State policies and non-state adaptations, as well as the vulnerability of the region’s forests to climatic stress and future anthropogenic change. The forests of Garhwal are critical to the larger Himalayan ecology, and the research findings point the way forward for developing potential adaptations that strengthen the concept of settling with/in forests.

Do urban habitats induce physiological changes in Mediterranean lizards?

AbstractUrban environments offer dramatically different habitats for wildlife compared with natural environments. They provide, for example, different levels of resource availability, anthropogenic night light, and microclimates (e.g., urban heat islands). For reptiles, increased temperatures in the city can lead to increased energetic demands and metabolic rates unless they change their morphology and physiology and adapt or acclimatize to the urban conditions. We explored differences in metabolic rate, evaporative water loss, and body size of two lizard species – rock agamas (Laudakia vulgaris) and Mediterranean house geckos (Hemidactylus turcicus), from urban habitats and nearby natural open areas. When tested in the lab, we expected to identify physiological adaptations resulting in decreased metabolism in urban individuals. Both species had similar body lengths and masses at both habitat types, suggesting any differences in costs and benefits between urban and natural environments do not affect their overall size or body condition. In the laboratory, metabolic rates were similar in individuals from both habitats for both species, indicating no long‐term adaptations in this trait. However, urban geckos (but not agamas) had higher evaporative water loss than conspecifics from more natural habitats. This may suggest different compositions of epidermal lipids affecting the gecko skin's resistance to evaporation between the habitats. Overall, our results highlight different elements of the urban environment that might affect reptiles. However, the differences between species urge caution in interpreting the results to other species and locations. With increasing urbanization worldwide, understanding when and to what degree local adaptations can occur can help us predict reptile species distribution and survival in light of future anthropogenic changes.

The effect of temperature and invasive alien predator on genetic and phenotypic variation in the damselfly Ischnura elegans: cross-latitude comparison

BackgroundUnderstanding and predicting how organisms respond to human-caused environmental changes has become a major concern in conservation biology. Here, we linked gene expression and phenotypic data to identify candidate genes underlying existing phenotypic trait differentiation under individual and combined environmental variables. For this purpose, we used the damselfly Ischnura elegans. Egg clutches from replicated high- (southern Sweden) and central-latitude (southern Poland) populations facing different degrees of seasonal time constraints were collected. Damselfly larvae were exposed to experimental treatments: current and mild warming temperatures crossed with the presence or absence of an invasive alien predator cue released by the spiny-cheek crayfish, Faxonius limosus, which is only present in Poland to date. We measured the following traits: larval development time, body size, mass and growth rate, and used the larvae for gene expression analysis by RNA-seq. Data were analysed using a multivariate approach.ResultsWe showed latitudinal differences in coping with mild warming and predator cues. When exposed to an increased temperature and a predator cue, central-latitude individuals had the shortest development and the fastest growth compared to high-latitude individuals. There was a general effect of predator cues regarding mass and growth rate reduction independent of latitude. Transcriptome analysis revealed that metabolic pathways related to larval anatomy and development tended to be upregulated in response to mild warming but only in fast-growing central-latitude individuals. Metabolic pathways linked to oxidative stress tended to be downregulated in response to a predator cue, especially in central-latitude individuals.ConclusionDifferent phenotypic and transcriptomic responses to environmental factors might be attributed to the variability in I. elegans life history strategies between the two latitudes caused by seasonal time constraints and to its coexistence with the invasive alien predator in nature. By providing insights into how organisms may respond to future anthropogenic changes, our results may be of particular interest in conservation biology.

Habitat loss increases seasonal interaction rewiring in plant–pollinator networks

Abstract Understanding the flexibility of interactions and network rewiring (i.e. reassembly of interactions due to partner‐switching) is necessary to comprehend how future anthropogenic changes will affect interspecific interactions and the functioning of communities. A higher rewiring could be expected in more disturbed landscapes because these landscapes contain fewer and more generalist species with more homogeneous traits. We sampled pollination interactions in 20 wild Olea europaea communities along a disturbance gradient to evaluate the hypothesis that the loss of natural habitats increases seasonal (within‐year) interaction rewiring in plant‐pollinator communities, influencing their functional structure. For this, we particularly tested whether rewiring frequency was negatively related to the extent of natural habitats surrounding the communities, whether interaction rewiring influenced the static structure of networks (nestedness, network specialization –H2'–), and whether a high generalization (low specialization –d'–) and abundance of species in communities made them more prone to rewiring. We show that habitat loss increased seasonal interaction rewiring in networks. Changes in rewiring were related to changes in the cumulative static structure of pollination networks. Nestedness decreased and network specialization (H2') also tended to decrease as interaction rewiring increased, suggesting an indirect effect of habitat loss on the robustness of networks through their dynamics. As expected, generalist insect and plant species were more prone to rewiring. However, flower abundance had different effects on the rewiring probability of plant species depending on the extent of habitat loss, with abundant species rewiring more in disturbed communities and rewiring less in more natural communities. Likely, this is related to the context‐dependent foraging behaviour of pollinators, which may switch to more abundant species if the cost of searching for trait‐matching resources is high in disturbed habitats. Our work shows the role of partner‐switching in generalist species to adapt to new conditions. It also highlights the importance of going beyond general network metrics to understand the underlying processes of community‐level interaction assembly and predict and anticipate the effects of anthropogenic disturbances on pollination services. Read the free Plain Language Summary for this article on the Journal blog.

Early Development Drives Variation in Amphibian Vulnerability to Global Change

Understanding how natural selection determines species’ life histories can reveal their resilience or sensitivity to anthropogenic changes. For example, the safe harbor hypothesis posits that natural selection will favor life histories that maximize the time spent in the safest life stages; a second theoretical prediction suggests that species with complex life histories will maximize the growth potential of a life stage relative to its safety. Amphibians exhibit complex life histories, with a diversity of developmental strategies occurring across taxa. Many strategies involve the complete elimination of a particular life stage, and thus provide an excellent opportunity to evaluate the main tenets of the safe harbor hypothesis and understand the consequences of this developmental variation for conservation of threatened amphibians. We develop a general framework for understanding developmental life histories of amphibians – including the special cases of paedomorphism, direct development, and viviparity – based on the relative growth potential and safety offered by aquatic and terrestrial habitat, which we tested using a global trait database. We then compare the IUCN Red List status of species differing in developmental mode, revealing that most fully aquatic species and species with an aquatic larval stage are currently of Least Concern, despite the fact that freshwater habitats are being lost at a much faster rate compared with terrestrial ecosystems. The higher proportion of direct developing and viviparous species that are threatened can be attributed to their smaller ranges, the fact that they are more likely to be found in rainforest habitats, and their relatively slow life histories. We conclude that an amphibian’s developmental mode reflects the relative costs and benefits of different habitats, and that this could contribute to the resilience or vulnerability of amphibians to future anthropogenic change.

A new species of Succinea (Gastropoda: Stylommatophora) from the Puna highlands of Argentina

A new species of Succinea Draparnaud, 1801, S. punasp. nov., from the Puna highlands in Catamarca Province, Argentina, is described. Seventeen water bodies were surveyed in the Puna ecoregion of Catamarca, with gastropods being found only at two localities, El Peñón and Guanchín River. We explored the morphological features of shells, reproductive system, radulae, and mandibles of specimens from each site. Although we found slight differences in the shell and the terminal genitalia, with specimens exhibiting an epiphallus folding over itself with terminal globular appearance, whereas others with an epiphallus cylindrical, we conclude that these are intraspecific variabilities. We used DNA sequences of the 16S-rRNA gene to explore genetic distances and genealogical relationships among both populations and other species of Succinea. We found maximum genetic interpopulation distances of up to 2.38%. Mean interspecific divergences among S. punasp. nov. and other Succinea species ranged between 7.14% and 15.21%. A secondary structure model of domains IV and V of the 16S-rRNA gene was developed, with polymorphic sites being concentrated in loop regions. A GIS analysis was carried out using a selection of bioclimatic variables to characterize the environment of the new species in comparison to other close Succinea species from South America. The analysis showed that the particular environmental conditions of the Puna in Catamarca are hardly present in other zones of South America, supporting our hypothesis that S.puna is endemic to that area. The restricted distribution of S. punasp. nov. in a single ecoregion with extreme climatic and physiographic characteristics, high altitude habitat and its microhabitat specialization, makes this species potentially vulnerable to impacts of future anthropogenic changes.

Adaptive optimal allocation of water resources response to future water availability and water demand in the Han River basin, China

Global warming and anthropogenic changes can result in the heterogeneity of water availability in the spatiotemporal scale, which will further affect the allocation of water resources. A lot of researches have been devoted to examining the responses of water availability to global warming while neglected future anthropogenic changes. What’s more, only a few studies have investigated the response of optimal allocation of water resources to the projected climate and anthropogenic changes. In this study, a cascade model chain is developed to evaluate the impacts of projected climate change and human activities on optimal allocation of water resources. Firstly, a large set of global climate models (GCMs) associated with the Daily Bias Correction (DBC) method are employed to project future climate scenarios, while the Cellular Automaton–Markov (CA–Markov) model is used to project future Land Use/Cover Change (LUCC) scenarios. Then the runoff simulation is based on the Soil and Water Assessment Tool (SWAT) hydrological model with necessary inputs under the future conditions. Finally, the optimal water resources allocation model is established based on the evaluation of water supply and water demand. The Han River basin in China was selected as a case study. The results show that: (1) the annual runoff indicates an increasing trend in the future in contrast with the base period, while the ascending rate of the basin under RCP 4.5 is 4.47%; (2) a nonlinear relationship has been identified between the optimal allocation of water resources and water availability, while a linear association exists between the former and water demand; (3) increased water supply are needed in the water donor area, the middle and lower reaches should be supplemented with 4.495 billion m3 water in 2030. This study provides an example of a management template for guiding the allocation of water resources, and improves understandings of the assessments of water availability and demand at a regional or national scale.

Future Warming and Intensification of Precipitation Extremes: A “Double Whammy” Leading to Increasing Flood Risk in California

AbstractThis study focuses on quantifying future anthropogenic changes in surface runoff associated with extreme precipitation in California's Sierra Nevada. The method involves driving a land surface model with output from a high resolution regional atmospheric simulation of the most extreme atmospheric rivers (ARs). AR events were selected from an ensemble of global climate model simulations of historical and late 21st century climate under the “high‐emission” RCP8.5 scenario. Average precipitation during the future ARs increases by ~25% but a much lower proportion falls as snow. The resulting future runoff increase is dramatic—nearly 50%, reflecting both the precipitation increase and simultaneous conversion of snow to rain. The “double whammy” impact on runoff is largest in the 2,000–2,500 m elevation band, where the snowfall loss and precipitation increase are both especially large. This huge increase in runoff during the most extreme AR events could present major flood control challenges for the region.

Brown Trout Spawn Timing, Redd Locations, and Stream Characteristics in Spearfish Creek within Spearfish, South Dakota, USA

This study documented brown trout (Salmo trutta) spawning locations, redd construction timing, and associated environmental variables in an 850-m long mainstem section and a 400-m long diversion channel of Spearfish Creek within the city limits of Spearfish, South Dakota, USA in 2019. The first redds were observed on October 15, with no new redds observed after November 12. Redd construction peaked during the first week of November, when 23 redds were observed in the mainstem section and 50 in the diversion channel. Substrate size was significantly smaller, water temperatures significantly higher, and water velocities significantly greater in redd versus non-redd locations in both the mainstem reach and the diversion channel (P ˚C), but significant, increase in water temperature from the rest of the channel locations. This is the first study to document redd locations in Spearfish Creek and will provide a baseline to evaluate future spawning activity, particularly as it may be affected by likely future anthropogenic changes potentially affecting the stream environment.

Retrospective eDNA assessment of potentially harmful algae in historical ship ballast tank and marine port sediments.

Microalgal bloom events can cause major ecosystem disturbances, devastate local marine economies, and endanger public health. Therefore, detecting and monitoring harmful microalgal taxa is essential to ensure effective risk management in waterways used for fisheries, aquaculture, recreational activity, and shipping. To fully understand the current status and future direction of algal bloom distributions, we need to know how populations and ecosystems have changed over time. This baseline knowledge is critical for predicting ecosystem responses to future anthropogenic change and will assist in the future management of coastal ecosystems. We explore a NGS metabarcoding approach to rapidly identify potentially harmful microalgal taxa in 63 historic and modern Australian marine port and ballast tank sediment samples. The results provide a record of past microalgal distribution and important baseline data that can be used to assess the efficacy of shipping guidelines, nutrient pollution mitigation, and predict the impact of climate change. Critically, eDNA surveys of archived sediments were able to detect harmful algal taxa that do not produce microscopic fossils, such as Chattonella, Heterosigma, Karlodinium, and Noctiluca. Our data suggest a potential increase in Australian harmful microalgal taxa over the past 30years, and confirm ship ballast tanks as key dispersal vectors. These molecular mapping tools will assist in the creation of policies aimed at reducing the global increase and spread of harmful algal taxa and help prevent economic and public-health problems caused by harmful algal blooms.

Spatiotemporal variability in seawater carbon chemistry for a coral reef flat in Kāne‘ohe Bay, Hawai‘i

AbstractCoral reef community composition and ecosystem function may change in response to anthropogenic ocean acidification. However, the magnitude of acidification on reefs will be modified by natural spatial and temporal variability in seawater CO2 chemistry. Consequently, it is necessary to quantify the ecological, biogeochemical, and physical drivers of this natural variability before making robust predictions of future acidification on reefs. In this study, we measured temporal and spatial physiochemical variability on a reef flat in Kāne‘ohe Bay, O‘ahu, Hawai‘i, using autonomous sensors at sites with contrasting benthic communities and by sampling surface seawater CO2 chemistry across the reef flat at different times of the day during June and November. Mean and diurnal temporal variability of seawater CO2 chemistry was more strongly influenced by depth gradients (~ 0.5–10 m) on the reef rather than benthic community composition. Spatial CO2 chemistry gradients across the reef flat reflected the cumulative influence from benthic metabolism, bathymetry, and hydrodynamics. Based on graphical assessment of total alkalinity–dissolved inorganic carbon data, reef metabolism in November was dominated by organic carbon cycling over inorganic carbon cycling, while these processes were closely balanced in June. Overall, this study highlights the strong influence of depth on reef seawater CO2 chemistry variability through its effects on benthic biomass to seawater volume ratio, seawater flow rates, and residence time. Thus, the natural complexity of ecosystems where a combination of ecological and physical factors influence reef chemistry must be considered when predicting ecosystem biogeochemical responses to future anthropogenic changes in seawater CO2 chemistry.

Palaeoclimate constraints on the impact of 2 °C anthropogenic warming and beyond

Over the past 3.5 million years, there have been several intervals when climate conditions were warmer than during the pre-industrial Holocene. Although past intervals of warming were forced differently than future anthropogenic change, such periods can provide insights into potential future climate impacts and ecosystem feedbacks, especially over centennial-to-millennial timescales that are often not covered by climate model simulations. Our observation-based synthesis of the understanding of past intervals with temperatures within the range of projected future warming suggests that there is a low risk of runaway greenhouse gas feedbacks for global warming of no more than 2 °C. However, substantial regional environmental impacts can occur. A global average warming of 1–2 °C with strong polar amplification has, in the past, been accompanied by significant shifts in climate zones and the spatial distribution of land and ocean ecosystems. Sustained warming at this level has also led to substantial reductions of the Greenland and Antarctic ice sheets, with sea-level increases of at least several metres on millennial timescales. Comparison of palaeo observations with climate model results suggests that, due to the lack of certain feedback processes, model-based climate projections may underestimate long-term warming in response to future radiative forcing by as much as a factor of two, and thus may also underestimate centennial-to-millennial-scale sea-level rise.

Past, present, and future of a freshwater fish metapopulation in a threatened landscape.

It is well documented that hydropower plants can affect the dynamics of fish populations through landscape alterations and the creation of new barriers. Less emphasis has been placed on the examination of the genetic consequences for fish populations of the construction of dams. The relatively few studies that focus on genetics often do not consider colonization history and even fewer tend to use this information for conservation purposes. As a case study, we used a 3-pronged approach to study the influence of historical processes, contemporary landscape features, and potential future anthropogenic changes in landscape on the genetic diversity of a fish metapopulation. Our goal was to identify the metapopulation's main attributes, detect priority areas for conservation, and assess the consequences of the construction of hydropower plants for the persistence of the metapopulation. We used microsatellite markers and coalescent approaches to examine historical colonization processes, traditional population genetics, and simulations of future populations under alternate scenarios of population size reduction and gene flow. Historical gene flow appeared to have declined relatively recently and contemporary populations appeared highly susceptible to changes in landscape. Gene flow is critical for population persistence. We found that hydropower plants could lead to a rapid reduction in number of alleles and to population extirpation 50-80 years after their construction. More generally, our 3-pronged approach for the analyses of empirical genetic data can provide policy makers with information on the potential impacts of landscape changes and thus lead to more robust conservation efforts.

Future Land-Use Changes and the Potential for Novelty in Ecosystems of the United States

Rapid global changes due to changing land use, climate, and non-native species are altering environmental conditions, resulting in more novel communities with unprecedented species combinations. Understanding how future anthropogenic changes may affect novelty in ecosystems is important to advance environmental management and ecological research in the Anthropocene. The main goal of this study was to understand how alternative scenarios of future land-use change may affect novelty in ecosystems throughout the conterminous United States. We used five spatially explicit scenarios of future land-use changes, reflecting different land-use policies and changes in agricultural markets, to quantify and map potential drivers of novelty. Our results showed large areas where future land-use changes may increase novelty in ecosystems. The major land-use changes known to increase novelty, including land abandonment and land-use expansion, were widespread in all scenarios (73 million to 95 million ha), especially in the eastern U.S. and along the West Coast. Our scenarios revealed that, at broad scales, future land-use changes will increase novelty in ecosystems, and that traditional conservation policies may have limited ability to prevent the process. In places such as the eastern U.S., conserving and maintaining historical conditions and associated biological diversity may become increasingly difficult due to future land-use changes and related ecological factors. Successful biodiversity conservation and environmental management in the Anthropocene will require novel conservation approaches to be relevant in areas with high levels of novelty in ecosystems.

Knowing the unknowns

AbstractThe Earth's atmosphere is not the only source of radiative forcing and anthropogenic climate change. As surely as people and civilizations have carbon footprints, they have albedo footprints as well. By altering the reflectivity of roughly half the land surface of the Earth in the past, mankind has made inadvertent geoengineering a part of the landscape of history. This worldwide alteration of reflectivity raises questions about the future of climate change, for albedo is a first‐order determinant of the Earth's radiative equilibrium. As surfaces absorb roughly 100 times more solar energy than the CO2 in the atmosphere, future anthropogenic changes in both land and water albedo may figure significantly in climate policy outcomes.

Bacterial pathogens, virulence mechanism and host defence in marine macroalgae

Macroalgae are important ecosystem engineers in temperate marine waters. The function of macroalgae is intimately linked to the composition and structure of their epibiotic bacterial, communities, and evidence has emerged that bacteria can also have a negative impact on their host by causing disease. A few examples exist where bacteria have been unambiguously linked to macroalgal disease, however in many cases, pathogenicity has not been clearly separated from saprophytic behaviour or secondary colonization after disease initiation. Nevertheless, pathogenic pressure by bacteria might be substantial, as macroalgae have evolved a range of innate and induced defence mechanism that have the potential to control bacterial attacks. The presence and abundance of virulence factors in marine bacteria, which have not previously been recognized as pathogens, also represents an underappreciated, opportunistic potential for disease. Given that virulence expression in opportunistic pathogens is often dependent on environmental conditions, we predict that current and future anthropogenic changes in the marine environment will lead to an increase in the occurrence of macroalgal disease. This review highlights important areas of research that require future attention to understand the link between environmental change, opportunistic pathogens and macroalgal health in the world's oceans.

Factors controlling primary productivity in a wet–dry tropical river

Algal production in rivers fuels foodwebs, and factors controlling this production ultimately affect food availability. Conversely, excessive algal production can have negative effects on higher trophic levels. The present study examined permanent waterholes in a disconnected wet–dry tropical river to determine the controls on algal production. Primary production in this river system was high compared with arid-zone and perennially flowing tropical rivers. Phytoplankton biomass increased over the dry season but this appeared to be because waterhole volume decreased, due to evaporation. Nitrogen (N) was the key limiting nutrient for phytoplankton, with rapid N turnover times, depletion of particulate 15N-nitrogen reflecting increasing N fixationover the dry season, and N stimulation in phytoplankton bioassays. The waterholes were shallow, providing sufficient light for accumulation of benthic algal biomass. Exclosure experiments were also conducted to determine the impact of top–down control on benthic algal biomass, with no evidence that exclusion of fish and crustaceans increased benthic algal biomass. The shallow off-channel waterhole in our study had substantially higher concentrations of nutrients and chlorophyll a than did the on-channel waterholes. This suggests that future anthropogenic changes, such as increased water extraction and increased nutrient inputs, could make the waterholes more vulnerable to deteriorating water quality, such as e.g. algal blooms, low concentrations of dissolved oxygen.

Assessment of future anthropogenic change and associated benthic risk in coastal environments using sedimentary metal indicators

Indicators of estuarine health are frequently compromised by large, natural temporal and spatial variance, which often mask long-term environmental trends and confound remedial actions. Ecosystem indicators seldom provide information on the pristine condition or the history of anthropogenic change of a water body. The current investigation used sedimentary metals and novel field and analytical techniques to determine the pristine condition and assess the magnitude and history of human-induced temporal and spatial change of an estuarine system. Two vintages of normalised metal concentrations in surficial sediment (1992 and 2007) indicate Cu and Zn concentrations have increased over the period, while Pb concentrations have declined - a change verified by strategically located sedimentary cores. Assuming no change in metals supply and dispersion, Cu and Zn are predicted to increase in concentration and areal extent, whereas Pb concentrations and areal cover will decrease. High concentrations of sedimentary Cu may be having an adverse affect on the health of benthic animals over extensive areas, which are predicted to expand if no remedial strategy is implemented.