Unvegetated Substrate Research Articles

Sediment carbon storage differs in native and non-native Caribbean seagrass beds

Non-native species are expanding globally and can alter ecosystem functions, including food web dynamics, community structure and carbon storage. Seagrass are foundation species that contribute a variety of ecosystem services in near-shore coastal ecosystems, including a significant sink of carbon. In the Caribbean, the rapidly expanding non-native Halophila stipulacea has unknown impacts on carbon storage. To investigate the impacts on carbon storage, we quantified organic carbon (Corg) content in sediment and seagrass tissues from monotypic H. stipulacea beds, mixed native seagrass beds dominated by Thalassia testudinum and Syringodium filiforme, and unvegetated substrate in St. John, USVI. We found native seagrass-vegetated sediment contained 1.3 times more Corg than sediment covered by H. stipulacea, and 1.6 times more Corg than unvegetated areas on average. Whereas, H. stipulacea-dominated substrate stored 1.2 times more Corg than unvegetated substrate. Likewise, native species contained 2.2 times more aboveground biomass and 6.0 times more belowground biomass than H. stipulacea. Since seagrasses are critical sources of carbon sequestration, our results suggest that invading H. stipulacea is associated with lower carbon stocks which has potential implications for conservation activities and climate change mitigation.

Environmental and taphonomic controls on the shell beds and fauna of the middle Miocene Chipola Formation of Florida, USA

Thick (2–10's m) and laterally extensive shell beds are common in the stratigraphic record, however, relatively little is known about their genesis since no single cause can explain the formation of these shell deposits. The goal of this study is to use lithologic, faunal, and taphonomic analyses to elucidate how the thick and laterally extensive shell beds of the middle Miocene Chipola Formation of Florida formed and became one of the most species-rich Cenozoic faunas in the western Atlantic Province. This study examined Chipola Formation outcrops at Alum Bluff, Cooter Bluff, and Farley Creek. Lithologic and trace fossil analyses indicate that the Alum Bluff shell bed represents an upper to middle shoreface setting, whereas the Farley Creek and Cooter Bluff shell beds represent lower shoreface and/or proximal offshore-transitional environments. Faunal data further support that Farley Creek and Cooter Bluff were deeper environments relative to Alum Bluff. Environmental preferences of most of the fauna indicate that all localities had normal, open-marine salinities with seagrass and unvegetated substrates. Samples are classified as within-habitat time-averaged assemblages, which were spatially averaged by various physical and ecological factors. Spatial averaging mixed the mosaic of communities that are represented by different types of substrate-controlled habitats within, but not across, significant variation in water depth. Finally, shell beds were accumulated by winnowing and/or high-energy events, such as storms, which produced the relatively thick, laterally extensive shell beds at each locality. Understanding the high diversity of the Chipola Formation is complicated and is likely best explained by multiple controls. Variation in alpha diversity among the localities is linked with differences in water depth as well as time and/or spatial averaging. The elevated diversity at each site was likely influenced by spatial averaging of habitats within a single depth zone, within-habitat time averaging, and poleward expansion of tropical taxa into the northern Gulf of Mexico due to environmental conditions associated with the middle Miocene Climatic Optimum. Similar poleward shifts of tropical taxa as those recorded in the Chipola Formation could hypothetically occur in the future as global temperatures and sea level rise. Future studies need to examine the biological changes associated with the middle Miocene Climatic Optimum to better understand the future impacts of ocean-climate change on marine communities.

Vegetation interactions with geotechnical properties and erodibility of salt marsh sediments

Salt marshes provide diverse ecosystem services including coastal protection, habitat provision and carbon sequestration. The loss of salt marshes is a global scale phenomenon, of great socio-economic concern due to the substantial benefits that they provide. However, the causes of spatial variability in marsh loss rates are inadequately understood for the purposes of predicting future ecosystem distributions and functions under global environmental change. This study investigated the relationship between the presence of different saltmarsh plants and the mechanical properties of the underlying substrate that relate to its vulnerability to erosion. Relationships between three halophytes (Puccinellia spp., Spartina spp. and Salicornia spp.) and sediment stability were assessed and compared to unvegetated substrates using in-situ and laboratory tests of substrate geotechnical properties and sediment characteristics. Sampling was conducted at two UK sites with contrasting sedimentology, one sand-dominated and one clay-rich. Sediment samples, collected simultaneously with measurements of shear strength, were analysed for moisture content, particle size and organic, carbonate and mineral compositions. These data were then used to explore the contribution of plant type, alongside the sedimentological parameters, to measured shear strength.Shear strength of the sediment varied between and, to a lesser extent, within sites, with the four cover types having a similar effect on shear strength within sites relative to each other. Sediments covered by Puccinellia spp exhibit the highest shear strength, while bare sediments exhibit the lowest. The effect of vegetation type on shear strength was greater in the coarser sediments of Warton Sands. Surface cover type made a significant contribution to exploratory statistical models developed for the prediction of sediment shear strength. The findings support existing recognition that vegetation can enhance sediment shear strengths but extend the insight to reveal differences in this effect that show generality between sedimentological settings. Further, the combination of methods provides insight into the fundamental mechanics by which various measures of sediment stability may be affected by different surface cover types. Cohesion appears to be a more appropriate descriptor of sediment erodibility than shear strength or friction angle and is most greatly enhanced by the presence of a fine, fibrous root system such as that of Puccinellia. A more detailed understanding of the multi-scale mechanisms by which plants confer strength to substrates is needed to better anticipate their impact on sediment erodibility, and therefore salt marsh vulnerability.

Spatial Patterns of Macrozoobenthos Assemblages in a Sentinel Coastal Lagoon: Biodiversity and Environmental Drivers

This study presents an assessment of the diversity and spatial distribution of benthic macrofauna communities along the Moulay Bousselham lagoon and discusses the environmental factors contributing to observed patterns. In the autumn of 2018, 68 stations were sampled with three replicates per station in subtidal and intertidal areas. Environmental conditions showed that the range of water temperature was from 25.0 °C to 12.3 °C, the salinity varied between 38.7 and 3.7, while the average of pH values fluctuated between 7.3 and 8.0. In vegetated habitats, biomass values of the seagrass Zostera noltei Hornemann ranged between 31.7 gDW/m² and 170.2 gDW/m² while the biomass of the seagrass Ruppia cirrhosa (Petagna) Grande between 54.2 gDW/m² and 84.7 gDW/m². Sediment analyses showed that the lagoon is mainly composed of sandy and silty sediments. We recorded 37,165 individuals of macrofauna distributed in 63 taxa belonging to 50 families, with a mean abundance value of 4582.8 ind/m² and biomass average of 22.2 g/m². Distance-based linear modeling analysis (DISTLM) identified sediment characteristics, water parameters and habitat type (biomass of Z. noltei) as the major environmental drivers influencing macrozoobenthos patterns. Our results clearly revealed that the hydrographic regime (marine and terrestrial freshwater), sediment distribution and characteristics and the type of habitat (vegetated vs. unvegetated substrate) are the key factors determining the species composition and patterns of macrozoobenthos assemblages.

Loss of seagrass results in changes to benthic infaunal community structure and decreased secondary production

Seagrass beds have decreased in abundance and areal coverage over the past several decades. Although previous studies have examined the importance of seagrass for benthic community assemblages and abundances, the effect of seagrass on deep-dwelling, large (high-biomass) infauna and the importance for benthic secondary production in Chesapeake Bay have not been addressed. Using benthic suctions and push cores, we compared density, diversity, and secondary productivity of benthic communities in seagrass to those in other shallow-water habitats and estimated benthic secondary productivity lost in the York River due to loss of seagrass from 1971 to 2016. We examined four habitat types in the York River: unvegetated, Gracilaria spp., mixed seagrass (multiple seagrass species), and Zostera marina L. seagrass. Physical characteristics of habitat types and biomass of organisms were assessed, and annual secondary productivity was calculated using biomass and production-to-biomass ratios. Benthic density, diversity, secondary productivity, sedimentary chlorophyll a, and percent sand were all highest in seagrass beds with Z. marina alone. Approximately 35% of benthic secondary productivity, or 1.51 × 108 g C yr–1, was lost in the York River in 1971–2016 due to the loss of seagrass beds to unvegetated substrate. The loss of seagrass in the York River over time and the associated decrease in benthic secondary productivity that we estimated could have negative consequences for the productivity of epibenthic predators. Our data emphasize the importance of conservation and restoration of seagrass.

A natural history model of New England salt marsh die-off.

Natural history gave birth to ecology and evolutionary biology, but today its importance is sometimes marginalized. Natural history provides context for ecological research, a concept that we illustrate using a consumer-driven vegetation die-off case study. For three decades, local predator depletion promoted the formation of high-density crab (Sesarma reticulatum) grazing and burrowing fronts, resulting in the spread of vegetation die-off through southern New England and Long Island marshes. We review results from a decade of research on this phenomenon and synthesize these findings with new field surveys, experiments, and historical reconstructions to test the hypothesis that the locations and processes of vegetation die-off and recovery are spatially predictable. We discovered that crab-driven die-off consistently begins on marsh creek heads, where peat and high flow conditions overlap, before spreading to inner creeks following peat availability, stunted cordgrass, and flow. Eventually, die-off eliminates most low marsh vegetation, leaving behind unvegetated substrate too soft to support burrows. Vegetation recovery exhibits the reverse patterns of die-off; it consistently begins in the low marsh within inner creeks, where soft substrate and low flow conditions overlap, before spreading to creek heads. This spatially explicit, substrate-dependent recovery eventually leads to ungrazed cordgrass abutting grazed cordgrass on the high marsh border. We present a conceptual model of die-off through recovery progression to provide managers and landowners with a diagnostic tool for identifying marsh die-off and recovery status. Collectively, this work illustrates the fundamental importance of long-term, natural history-based investigations of ecosystem dynamics in informing ecology, conservation, and management practices.

Greywater impact on green roofs’ provision of ecosystem services

Previous research showed that some herbaceous perennial species could offer summertime cooling better than succulent species on green roofs (GRs), if supplementary irrigation is available during times of drought. In light of increasing water shortages, use of greywater (GW) instead of mains tap water (TW) for this purpose comes into focus. A glasshouse experiment was conducted in summer 2015 at the University of Reading (UK) to assess the impact of GW irrigation on the health, growth and functioning (in terms of leaf stomatal conductance (gs) and associated water uptake) of four plant genotypes (Salvia, Stachys, Heuchera and Sedum), and their ability to deliver ecosystem services, particularly cooling. Twenty-two replicates of each genotype, plus controls of bare, unvegetated substrate, were irrigated with fixed volumes of TW or synthetic GW for 6 weeks. Plant growth and visual quality, and gs were measured. In Week 7, daily water loss from each container following saturation was determined. For the first 6 weeks, plant growth, visual quality and gs were similar for both TW and GW treatments for all genotypes, indicating no negative impact of short-term GW irrigation and no apparent impact on cooling when plants were well-watered. However, in Week 7 water uptake (and thus presumably gs) was significantly lower for plants irrigated with GW compared to TW for some genotypes (Salvia and Heuchera), especially as substrate became drier, suggesting a reduction in evapotranspiration and potentially reduced cooling service when the soil is dry.

Compositional Signatures in Acoustic Backscatter Over Vegetated and Unvegetated Mixed Sand‐Gravel Riverbeds

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high‐frequency, decimeter‐resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand‐gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small‐scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two‐stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain‐scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam‐to‐beam) bed‐sonar geometry, are removed. Then, coherent scales between high‐resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high‐pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low‐frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

The fundamental role of ecological feedback mechanisms for the adaptive management of seagrass ecosystems-a review.

Seagrass meadows are vital ecosystems in coastal zones worldwide, but are also under global threat. One of the major hurdles restricting the success of seagrass conservation and restoration is our limited understanding of ecological feedback mechanisms. In these ecosystems, multiple, self-reinforcing feedbacks can undermine conservation efforts by masking environmental impacts until the decline is precipitous, or alternatively they can inhibit seagrass recovery in spite of restoration efforts. However, no clear framework yet exists for identifying or dealing with feedbacks to improve the management of seagrass ecosystems. Here we review the causes and consequences of multiple feedbacks between seagrass and biotic and/or abiotic processes. We demonstrate how feedbacks have the potential to impose or reinforce regimes of either seagrass dominance or unvegetated substrate, and how the strength and importance of these feedbacks vary across environmental gradients. Although a myriad of feedbacks have now been identified, the co-occurrence and likely interaction among feedbacks has largely been overlooked to date due to difficulties in analysis and detection. Here we take a fundamental step forward by modelling the interactions among two distinct above- and belowground feedbacks to demonstrate that interacting feedbacks are likely to be important for ecosystem resilience. On this basis, we propose a five-step adaptive management plan to address feedback dynamics for effective conservation and restoration strategies. The management plan provides guidance to aid in the identification and prioritisation of likely feedbacks in different seagrass ecosystems.

Mitigation of Acid Mine Drainage via a Revegetation Programme in a Closed Coal Mine in Southern New Zealand

Acid mine waters (pH 3–5) at the closed Wangaloa coal mine have resulted from surface runoff and groundwater seepage in contact with pyrite-bearing waste rock piles. The low nutrient content, physical factors, and elevated boron levels, all combined with the low pH (down to pH 2) of most waste rocks have limited early planned revegetation and natural plant colonisation. A renewed programme of site rehabilitation, started in 2000, focussed on establishment of near-complete ground cover and functioning ecosystems. Small patches (tens of m2) of low-pH, boron-rich, unvegetated substrates persist after more than 10 years of rehabilitation and introduction of a wide variety of species, but natural colonisation is slowly advancing on these remnants. The rehabilitation has coincided with and contributed to a rise in runoff water pH from ≈4.5 to ≈5.6. This decrease in severity of acid mine drainage (AMD) has apparently become sustainable without further intervention. Near-complete vegetative cover occurred by a combination of a major planting programme and natural colonisation from nearby islands of established native species. Both processes were accompanied by development of functioning ecosystems, and supported by increasing invertebrate diversity and abundance, which are ensuring the persistence of the ameliorative effects on AMD at the site. Vegetation established via natural processes can function ecologically at a higher level than comparable planted vegetation but may not lead to the desired plant cover on some substrates.

Colonization patterns of decapods into artificial collectors: seasonality between habitat patches

Understanding colonization of new habitats by recruits is essential to comprehend local abundance patterns of adult populations. Colonization of benthic habitats by new colonizers is achieved through the influx of larvae from the water column and movements from adjacent habitats. Colonization, i.e., the composition and abundance of new colonizers, into a focal habitat may be affected by surrounding habitats. In this study, we investigated seasonal variation through an annual cycle in postlarval settlement patterns of decapod crustaceans colonizing artificial collectors on different habitats, in particular: Cymodocea nodosa seagrass meadows, sandy patches, ‘urchin-grazed’ barrens and macroalgal-dominated beds, which are arranged in patches within seascapes in the eastern Atlantic. Our results showed that: 1) decapods, at least some species, settle preferentially on artificial collectors deployed on vegetated substrates when compared to those deployed on unvegetated substrates; 2) despite most decapods have a planktonic larval phase with wide oceanic dispersal, the presence of crustaceans in particular habitats suggests a great specificity at their early post-larval stages; and 3) although subtropical waters of Gran Canaria have a weak seasonal variation, early postlarval stages of decapod crustaceans showed two distinct settlement periods, i.e., a ‘cold’ and a ‘warm’ season.

Seasonal regulation of nitrification in a rooted macrophyte (Vallisneria spiralis L.) meadow under eutrophic conditions

Variable oxygen release from the root of macrophytes growing in ammonium-rich organic substrates can stimulate the process of nitrification. To verify this hypothesis, we performed seasonal measurements of potential nitrification activity in sediments with and without the perennial submersed plant Vallisneria spiralis L. (Hydrocharitaceae). Pore water and sediment features were simultaneously considered in order to provide insights into the regulation of the process. Results demonstrated a significant effect of season and plant presence on potential nitrification activity, with higher rates in winter and lower rates in summer. Vegetated sediment displayed lower pore water ammonium, but always higher potential nitrification activity compared to the unvegetated substrate, regardless the season. Nitrification activity was strongly correlated with pore water redox status, which were affected by both season and plant presence. Along its annual cycle V. spiralis promoted more oxidized conditions in the rhizosphere likely due to elevated radial oxygen loss and the consequent maintenance of a larger nitrifying community. These outcomes confirm the results of a limited number of studies that demonstrated how sediment biogeochemistry may be controlled by plant-released oxygen also in organic-rich systems.

Consequences of Least Tern (Sternula antillarum) microhabitat nest-site selection on natural and mechanically constructed sandbars in the Missouri River

Abstract. Nest-habitat selection in colonial species has rarely been assessed at multiple spatial scales to evaluate its fitness consequences. Management for the federally endangered U.S. Interior population of Least Terns (Sternula antillarum) has focused on maintenance of breeding habitats, including mechanical construction of sandbars from dredged material. Least Terns are attracted to large areas of unvegetated substrate, yet small-scale habitat features are thought to trigger selection for nesting. We evaluated nest-scale habitat selection to determine (1) whether selection differs between constructed and natural sandbars and (2) the subsequent consequences of habitat selection on nest success. During 2006–2008, we examined 869 Least Tern nest sites on constructed and natural sandbars in the Missouri River for evidence of microhabitat selection at the nest in relation to habitat within the surrounding 3-m area. Least Tern nest sites had coarser and larger substrate materials at the nest, more debris,...

Effect of habitat complexity on predation success: re-evaluating the current paradigm in seagrass beds

The complex structure of seagrass beds provides increased protection for prey com- pared to unvegetated substrates. Additionally, most studies support the notion that predation inten- sity is negatively correlated with seagrass density. However, virtually every study to previously test this idea has used the same number of predators and prey across a gradient of seagrass density treat- ments. This design ignores another well-established fact: invertebrate and fish abundance increase with increasing seagrass density. Therefore, it makes sense to carry out predation experiments that increase the number of both predators and prey as seagrass density increases. Outdoor tank experi- ments (7 density treatments: 0 to 3000 leaves m -2 ) were carried out using artificial seagrass units modeled after turtlegrass Thalassia testudinum and field mesocosm experiments (4 density treat- ments: 0 to 3000 leaves m -2 ) in living T. testudinum in Big Lagoon (Florida, USA). In these experi- ments the absolute number of predators (the pinfish Lagodon rhomboides) and prey (grass shrimp Palaemonetes pugio) were increased with increasing seagrass density. Both experiments yielded similar results: the only significant difference in predation rate was between the unvegetated treat- ment and the seagrass treatments as a group. These results suggest that dense seagrass does not nec- essarily provide increased protection for prey organisms.

Habitat preference of three common fishes for seagrass, Caulerpa taxifolia, and unvegetated substrate in Moreton Bay, Australia

A decrease in seagrass cover and a commensurate increase in Caulerpa taxifolia distribution in Moreton Bay have prompted concern for the impact that habitat change may have on faunal communities. Therefore, it is important to understand the patterns of habitat use. We examined habitat selection of three common seagrass species: double-ended pipefish (Syngnathoides biaculeatus), eastern trumpeter (Pelates quadrilineatus), and fan-bellied leatherjacket (Monacanthus chinensis) using a mesocosm experiment. Fish were given three possible habitat pairings (1) seagrass and C. taxifolia, (2) seagrass and unvegetated, and (3) C. taxifolia and unvegetated. Observation trials were conducted during the day and night over two days. In all trials, fish preferred vegetated habitat (seagrass or C. taxifolia) over unvegetated habitat (sand). In seagrass and C. taxifolia trials, all species preferred seagrass significantly over C. taxifolia. Habitat use patterns did not differ between day and night trials. Caulerpa taxifolia provides a valuable structured habitat in the absence of seagrass; however, it is unclear if C. taxifolia meadows provide other resource benefits to fishes beyond that of shelter.

Long-term changes in a northern Baltic macrophyte community

Over the last 45 years significant changes in the floristic composition, distribution pattern, and dominance structure of phytobenthos were observed in Haapsalu Bay. Although the species composition of macroalgae did not change much over the course of this study, we observed notable changes in the community structure, i.e. algal shares. Some species, e.g. Tolypella nidifica, disappeared, other species such as Chara connivens and Chara baltica appeared for the first time in the study area. Besides, many prevailing species were relocated within the observed area over the course of the study. Another distinct feature of the recent years is that the vegetation had no dominant species. In general decadal variability exceeded yearly variability. There was no single abiotic variable that exerted major influence on phytobenthic communities. Instead we observed a combined effect of multiple environmental variables on phytobenthos communities. This study indicated that the changes in phytobenthic communities in Haapsalu Bay over the last 45 years were mainly due to large-scale weather patterns that determined regional salinity and ice conditions. Salinity sets the dominance pattern of phytobenthic species of freshwater and marine origin within communities. The intensity of ice scrape in turn created new unvegetated substrate and determined the overall phytobenthic cover in the study area. Within these large-scale patterns exposure, depth, and spatial salinity gradients contributed to the variability of small-scale patterns of macrophyte communities. Regional nutrient loading had weak effects on macrophyte communities, mainly in interactions with local abiotic variables and regional weather patterns.

Increased habitat structure does not always provide increased refuge from predation

Submerged aquatic vegetation (SAV) usually hosts higher numbers of both inverte- brates and fish than do unvegetated substrates. In addition, based on prior laboratory experiments predation risk is thought to decrease with increasing SAV biomass or stem/shoot density, resulting in higher abundance and diversity of potential prey species in dense vegetation. However, all previous tests of the effects of vegetation on prey capture have been similar: constant numbers of predators and prey have been tested at different vegetation densities. Because sampling has repeatedly shown that the abundance of both predators and prey increases with increasing SAV density, an experiment that tests the effects of increasing SAV density on prey capture would mirror reality more closely than would the design of prior experiments and would also allow predator and prey numbers to increase. Thus, in laboratory trials we increased the number of predators (pinfish Lagodon rhomboides (Linnaeus)) and prey (grass shrimp Palaemonetes pugio Hulthuis) in proportion to increases in SAV shoot density to re-evaluate whether increasing SAV density altered prey survival rates under these more realistic conditions. Treatments included an unvegetated substrate and 3 different densities (400, 2000 and 4000 leaves m -2 of artificial SAV (mimicking turtlegrass Thalassia testudinum Banks and Sol). Our results conflicted with those of prior experiments and showed no significant differences in grass shrimp survival among the different SAV densities (although there was greater grass shrimp survival in SAV than on unvegetated substrate), and indicated that increasing vegetation density will not consistently lead to proportionally greater prey survival rates.

Indirect estimation of benthic secondary production in the Lagoon of Venice (Italy)

Five published indirect methods to estimate benthic secondary production of intertidal mudflats and a new proposed formulation based on quarter-power allometric scaling and the “Universal Temperature Dependence” of biological processes (UTD) were compared. For this purpose, a dataset consisting of an annual series of samples, taken from the Lagoon of Venice from March 1996 to March 1997, at sites characterised by different seagrass coverage was used. All methods resulted in that biomass and secondary production decreased progressively when moving from the seagrass meadow toward areas of unvegetated substrate, suggesting an influence of the available marine phanerogams on the neighbouring sites. The equation proposed in this paper gives results comparable with those obtained using empirical regression models from literature. The main conclusion from this study is that general equations proposed by the “metabolic theory of ecology” can be applied for indirect estimations of secondary production of benthic communities.

Piping Plovers Nesting Amongst Cottonwood Saplings

Abstract Piping Plovers (Charadrius melodus) typically nest on unvegetated sand or gravel substrates throughout their breeding range. We report on the atypical habitat characteristics of four Piping Plover nests that we found amongst young cottonwood (Populus deltoides) saplings on a sandbar island in the Missouri River along the South Dakota-Nebraska border. Atypical habitat use could have implications for estimating demographic parameters and management of this protected species. It is important to explore the extent to which Piping Plovers use atypical breeding habitat throughout their range and the quality of this potentially poor habitat.

Ecosystem Goods and Services from Swedish Coastal Habitats: Identification, Valuation, and Implications of Ecosystem Shifts

Coastal areas are exposed to a variety of threats due to high population densities and rapid economic development. How will this affect human welfare and our dependence on nature's capacity to provide ecosystem goods and services? This paper is original in evaluating this concern for major habitats (macroalgae, seagrasses, blue mussel beds, and unvegetated soft bottoms) in a temperate coastal setting. More than 40 categories of goods and services are classified into provisional, regulating, and cultural services. A wide variety of Swedish examples is described for each category, including accounts of economic values and the relative importance of different habitats. For example, distinguishing characteristics would be the exceptional importance of blue mussels for mitigation of eutrophication, sandy soft bottoms for recreational uses, and seagrasses and macroalgae for fisheries production and control of wave and current energy. Net changes in the provision of goods and services are evaluated for three cases of observed coastal ecosystem shifts: i) seagrass beds into unvegetated substrate; ii) unvegetated shallow soft bottoms into filamentous algal mat dominance; and iii) macroalgae into mussel beds on hard substrate. The results are discussed in a management context including accounts of biodiversity, interconnectedness of ecosystems, and potential of economic valuation.