Recovering Ecosystem Functions in a Restored Salt Marsh by Leveraging Positive Effects of Biodiversity

Natural and managed ecosystems provide a variety of ecological, economic, and cultural benefits; yet most have been altered by human activity such that they exhibit deficits in both biodiversity and functionality. Identifying factors accelerating the recovery of key species and associated functions in degraded systems is therefore a global priority. We tested the hypotheses that explicitly incorporating biodiversity into restoration design will lead to greater ecosystem function and that positive effects of diversity will strengthen over time due to an increase in the importance of complementarity relative to selection effects. We did this by manipulating salt marsh plant species richness across a tidal elevation gradient as part of a coastal wetland restoration project in southern California. Overall, diversity enhanced biomass accumulation in experimental plots, with the magnitude of the effect strengthening from one to three years post-restoration due to a combination of decreasing performance in monocultures and increasing performance in multispecies mixtures over time. Positive diversity effects were initially due exclusively to selection, as mixtures were dominated by species also exhibiting high performance in monoculture, although the identity of the highest performing species varied across tidal elevations and over time. By the end of the study, complementarity, indicative of niche partitioning and/or positive interactions among species, contributed to productivity at least as much as selection effects. Our study provides real-world support for a recent theoretical model predicting strong positive biodiversity effects when functionally different species coexist in a heterogeneous landscape. Incorporating biodiversity into restoration designs can result in net gains in ecosystem function especially in low diversity systems, yet shorter experiments lacking broad environmental and species trait variability may both underestimate the strength of and misidentify the mechanisms underlying positive diversity effects

DINOSAUR FOOTPRINTS FROM THE GLEN ROSE FORMATION (PALUXY RIVER, DINOSAUR VALLEY STATE PARK, SOMERVELL COUNTY, TEXAS)

Dinosaur footprints are found in the Glen Rose Formation and other Lower Cretaceous stratigraphic units over much of central Texas (Pittman, 1989; Rogers, 2002; Farlow et al., 2006). Dinosaur tracks were discovered in the rocky bed of the Paluxy River, near the town of Glen Rose, Texas, early in the 20th Century (Jasinski, 2008; Farlow et al., 2012b). Ellis W. Shuler of Southern Methodist University did pioneering studies on the dinosaur tracks (Shuler 1917, 1935, 1937), and Langston (1974) summarized much of the early literature. What really put the dinosaur footprints of the Paluxy River on the map, though, were the herculean efforts that Roland T. Bird of the American Museum of Natural History made to secure trackway slabs for display at that institution and at the Texas Memorial Museum in Austin (Bird, 1985; Jasinski, 2008). In 1970 Dinosaur Valley State Park was created to protect the dinosaur footprints. This guidebook briefly summarizes earlier work, and also serves as an interim report of research of our group still in progress, concerned with identifying the makers of the Paluxy River footprints, and determining what those animals were up to as they made their tracks. We will offer some comparisons of the dinosaur tracks of the Glen Rose Formation with those from other ichnofaunas around the world. The last quarter-century has seen an explosive increase in the technical literature dealing with dinosaur footprints, and we cannot possibly cite all of the relevant studies. For the sake of brevity we will emphasize publications from the present century, and summary papers and books, as much as possible. Even with this restriction, however, the literature is so vast that the literature-cited “tail” of this report starts to wag the “dog” of the text

Uptake of algal carbon and the likely synthesis of an "essential" fatty acid by Uvigerina ex. gr. semiornata (Foraminifera) within the Pakistan margin oxygen minimum zone:evidence from fatty acid biomarker and C-13 tracer experiments

Foraminifera are an important component of benthic communities in oxygen-depleted settings, where they potentially play a significant role in the processing of organic matter. We tracked the uptake of a 13C-labelled algal food source into individual fatty acids in the benthic foraminiferal species Uvigerina ex. gr. semiornata from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were conducted on the Pakistan margin during the late/post monsoon period (August–October 2003). A monoculture of the diatom Thalassiosira weisflogii was 13C-labelled and used to simulate a pulse of phytoplankton in two complementary experiments. A lander system was used for in situ incubations at 140 m water depth and for 2.5 days in duration. Shipboard laboratory incubations of cores collected at 140 m incorporated an oxystat system to maintain ambient dissolved oxygen concentrations and were terminated after 5 days. Uptake of diatoms was rapid, with a high incorporation of diatom fatty acids into foraminifera after ~ 2 days in both experiments. Ingestion of the diatom food source was indicated by the increase over time in the quantity of diatom biomarker fatty acids in the foraminifera and by the high percentage of 13C in many of the fatty acids present at the endpoint of both in situ and laboratory-based experiments. These results indicate that . ex. gr. semiornata rapidly ingested the diatom food source and that these foraminifera will play an important role in the short-term cycling of organic matter within this OMZ environment. The presence of 18:1(n-7) in the experimental foraminifera suggested that U. ex. gr. semiornata also consumed non-labelled bacterial food items. In addition, levels of 20:4(n-6), a PUFA only present in low amounts in the diatom food, increased dramatically in the foraminifera during both the in situ and shipboard experiments, possibly because it was synthesised de novo. This "essential fatty acid" is often abundant in benthic fauna, yet its origins and function have remained unclear. If U. ex. gr. semiornata is capable of de novo synthesis of 20:4(n-6), then it represents a potentially major source of this dietary nutrient in benthic food webs

Evaluating the Functional Recovery of Restored Coastal Wetland in Southern California

Within the Huntington Beach Wetlands (HBW), we hypothesized that Brookhurst and Magnolia Marshes (marsh areas isolated from tidal influence for approximately 100 years) would have significantly different physical characteristics (salinity, temperature, moisture, sediment parameters), more terrestrial plant, algal, invertebrate and microbial communities and altered food web structure from neighboring Talbert Marsh (a marsh area whose tidal connect was restored 20 years ago). In addition, we hypothesized that once Brookhurst Marsh was restored (Summer 2009), these differences would decrease and with time, resemble those of Talbert Marsh. This restoration of structure and function will occur on differing time scales; we predicted that physical parameters would quickly become similar while algal, invertebrate and microbial communities would begin to change on a month-year time scale. Changes to the plant community and the food web structure are anticipated to occur on a year-decadal time scale (beyond the funding cycle for this project)

Estuarine Vegetation at Rush Ranch Open Space Preserve, San Franciso Bay National Estuarine Research Reserve, California

The Rush Ranch Open Space Preserve (Rush Ranch) is located at the northwestern edge of the Potrero Hills and includes the largest remaining undiked tidal wetland within the Suisun Marsh region of the San Francisco Estuary. The brackish tidal wetlands grade into the transitional vegetation and undeveloped grasslands of the Potrero Hills, and we describe diverse vegetation that reflects the estuarine position, land use history, and hydrogeomorphic complexity of the site.We present a useful framework for future study of vegetation at this San Francisco Bay National Estuarine Research Reserve site. Rush Ranch includes four major estuarine geomorphic units that are widely distributed in the region and support vegetation: subtidal channel beds, fringing tidal marsh, tidal marsh plain and tidal marsh–terrestrial ecotone. These are distinguished by small variations in hydrology and elevation, as noted and described through field observations and historic vegetation-mapping data. We discuss vegetation within each of these landforms, considering each vegetation community as a function of changing physical environment and biological interactions. Past land use and exotic plant species invasions have substantially altered Rush Ranch's tidal marsh vegetation patterns. Our results indicate 27% of the current estuarine wetland-associated flora at Rush Ranch are exotic species, and several are highly invasive. Despite these influences, Rush Ranch’s position in the landscape provides important and increasingly rare habitat linkages between the tidal marsh and upland grasslands, which allows great potential for restoration and enhancement. We present a detailed flora and vegetation analysis by hydrogeomorphic setting to provide an ecological framework for future monitoring, research, and adaptive conservation management at Rush Ranch.

Estuarine Vegetation at Rush Ranch Open Space Preserve, San Franciso Bay National Estuarine Research Reserve, California

The Rush Ranch Open Space Preserve (Rush Ranch) is located at the northwestern edge of the Potrero Hills and includes the largest remaining undiked tidal wetland within the Suisun Marsh region of the San Francisco Estuary. The brackish tidal wetlands grade into the transitional vegetation and undeveloped grasslands of the Potrero Hills, and we describe diverse vegetation that reflects the estuarine position, land use history, and hydrogeomorphic complexity of the site.We present a useful framework for future study of vegetation at this San Francisco Bay National Estuarine Research Reserve site. Rush Ranch includes four major estuarine geomorphic units that are widely distributed in the region and support vegetation: subtidal channel beds, fringing tidal marsh, tidal marsh plain and tidal marsh–terrestrial ecotone. These are distinguished by small variations in hydrology and elevation, as noted and described through field observations and historic vegetation-mapping data. We discuss vegetation within each of these landforms, considering each vegetation community as a function of changing physical environment and biological interactions. Past land use and exotic plant species invasions have substantially altered Rush Ranch's tidal marsh vegetation patterns. Our results indicate 27% of the current estuarine wetland-associated flora at Rush Ranch are exotic species, and several are highly invasive. Despite these influences, Rush Ranch’s position in the landscape provides important and increasingly rare habitat linkages between the tidal marsh and upland grasslands, which allows great potential for restoration and enhancement. We present a detailed flora and vegetation analysis by hydrogeomorphic setting to provide an ecological framework for future monitoring, research, and adaptive conservation management at Rush Ranch.

Spatial Hedonic Valuation of a Multiuse Urban Wetland in Southern California

Most of Southern California’s wetlands have disappeared despite being critical ecosystems with many valuable attributes. Many of the wetlands that remain are in relatively urban areas, are severely degraded, and may not function properly. Using hedonic spatial error models, we measure the economic value of living near an urban multi-use wetland in Long Beach, California. Both sales prices and estimated values are used in the analysis. Results show that proximity to wetlands increases residential property values in the focus area. This analysis provides important information for policymakers to justify ongoing restoration projects and prevent further degradation of urbanized natural resources

Contrasted Impacts of Yellow Flag Iris (Iris pseudacorus) on Plant Diversity in Tidal Wetlands within Its Native and Invaded Distribution Ranges

We conducted an intercontinental biogeographic survey to analyze the effects of an invasive plant species in its native and invaded ranges. Our study system included tidal wetlands colonized by Iris pseudacorus L. (yellow flag iris, Iridaceae) along salinity gradients in two estuaries in its native European (Guadalquivir Estuary) and invaded North American (San Francisco Bay-Delta Estuary) ranges. We hypothesized I. pseudacorus would impart more negative community-level impacts on plant species diversity in the invaded range compared to the native range. Our results show that the colonization of Iris pseudacorus has very different effects on the diversity of tidal plant communities in its native and invaded ranges. In the native range, I. pseudacorus promoted plant diversity by increasing evenness and species richness. On the contrary, I. pseudacorus greatly reduced plant diversity in the invaded range, being this reduction higher in those communities with higher species richness and diversity levels. In view of these results, urgent management practices are needed to control and eradicate I. pseudacorus from the inland Sacramento-San Joaquin Delta Estuary since this invasive macrophyte is reducing plant diversity at local and landscape scales

Contrasted Impacts of Yellow Flag Iris (<i>Iris pseudacorus</i>) on Plant Diversity in Tidal Wetlands within Its Native and Invaded Distribution Ranges

We conducted an intercontinental biogeographic survey to analyze the effects of an invasive plant species in its native and invaded ranges. Our study system included tidal wetlands colonized by Iris pseudacorus L. (yellow flag iris, Iridaceae) along salinity gradients in two estuaries in its native European (Guadalquivir Estuary) and invaded North American (San Francisco Bay-Delta Estuary) ranges. We hypothesized I. pseudacorus would impart more negative community-level impacts on plant species diversity in the invaded range compared to the native range. Our results show that the colonization of Iris pseudacorus has very different effects on the diversity of tidal plant communities in its native and invaded ranges. In the native range, I. pseudacorus promoted plant diversity by increasing evenness and species richness. On the contrary, I. pseudacorus greatly reduced plant diversity in the invaded range, being this reduction higher in those communities with higher species richness and diversity levels. In view of these results, urgent management practices are needed to control and eradicate I. pseudacorus from the inland Sacramento-San Joaquin Delta Estuary since this invasive macrophyte is reducing plant diversity at local and landscape scales