The Use of Case Studies in Establishing Feasibility for Wetland Restoration

Establishing restoration feasibility is a multifaceted process that requires consideration of the ecological, social, and economic conditions of a given site. Examining completed restoration projects that report successes and failures may enhance this complex decision‐making process. We describe five completed wetland restoration projects and identify commonalities among them to inform the process of establishing feasibility for proposed restoration projects. Most of the case studies identified the need to gather preexisting and historical information, develop scenarios through hydrologic modeling, study the restoration materials, use best professional judgement for unanswered questions, establish multigroup collaboration, gain public support from stakeholders, and monitor postrestoration. We applied these lessons to a study that evaluated the feasibility of restoring Dyke Marsh Preserve, a tidal freshwater marsh in Virginia that the National Park Service is mandated to preserve. We found that the use of case studies substantially increased confidence in the decision‐making process by focusing discussions on the most important ecological, social, and economic aspects of a potential restoration.     

DIETS OF COASTAL BOTTLENOSE DOLPHINS FROM THE U. S. MID-ATLANTIC COAST DIFFER BY HABITAT

We recorded 31 species in the stomachs of 146 coastal bottlenose dolphins ( Tursiops truncatus ) from North Carolina, U. S. A. Sciaenid fishes were the most common prey (frequency of occurrence = 95%). By mass, Atlantic croaker ( Micropogonias undulatus ) dominated the diet of dolphins that stranded inside estuaries, whereas weakfish ( Cynosicon regalis ) was most important for dolphins in the ocean. Inshore squid ( Loligo sp.) was eaten commonly by dolphins in the ocean, but not by those in the estuaries. There was no significant pattern in prey size associated with dolphin demography, but the proportion of the diet represented by croaker was higher for males than for females, and mature dolphins ate more croaker than did juveniles. Dietary differences between dolphins that stranded in the estuaries and those that stranded on ocean beaches support the hypothesis that some members of the population inhabit the ocean primarily while others reside principally in estuaries. The overwhelming majority of prey were soniferous species (75% of numerical abundance), which is consistent with the hypothesis that bottlenose dolphins use passive listening to locate noise-making fishes. However, spatiotemporal patterns in consumption of Sciaenid fishes did not coincide with their spawning, which is when peak sound production is thought to occur.     

Is global climate change influencing the overwintering distribution of weakfish Cynoscion regalis?

The pattern of stable isotope signatures in a sub-sample of 67 juvenile weakfish Cynoscion regalis, captured at the mouth of the Christina River, 113 km upstream of the mouth of Delaware Bay (U.S.A) in the autumn of 2000, suggested that they resided at the location since recruitment. The possibility that young C. regalis departed from the generally characteristic life-history pattern of marine migrants at this latitude, i.e . emigrating offshore with the adults in autumn was bolstered by the collection of 69 individuals during the winters of 2000–2006 from the travelling screens of a power plant located at river kilometre 88 including an 118 mm total length juvenile captured in mid-February 2006.     

Developing and Communicating a Taxonomy of Ecological Indicators: A Case Study from the Mid-Atlantic

To ensure indicators of ecosystem health are integrated into environmental decision-making, it is imperative to provide a comprehensive framework for indicator selection and use. The same framework can also be used to evaluate the utility of any given indicator. The Atlantic Slope Consortium (ASC) has developed such a framework, based upon three primary elements: 1) The specific questions to be answered (the type of indicator), recognizing the following types of questions/indicators: Condition assessment: snapshot of the current state of the system; Stressor diagnosis: identification of causative factors of condition; Communication to the public: encouraging comprehension of condition in its most elementary or integrated form; Futures assessment: estimating the probable trajectory of condition, or assessing the vulnerability of any system to a stochastic event; Evaluation: a subset of condition indicators that evaluate the effectiveness of management actions. 2) The spatial and/or temporal scale of the issue being addressed (the spatial/temporal scale over which the indicator is valid). 3) The context of the question, using categories of surrounding land use as surrogates for social choices. A Fish Community Index (FCI) developed for the ASC will provide an example of utilizing the framework to select an indicator, as well as using the framework to judge the utility of the indicator.     

Integration of Environmental Indicators for the U.S. Mid-Atlantic Region

The Mid-Atlantic Integrated Assessment (MAIA) Project began in 1994 as a partnership between the U.S. Environmental Protection Agency's (USEPA's) Region III Office and the Office of Research and Development. This multiyear initiative was envisioned to: (1) improve the quality of environmental science and promote the use of sound science in environmental decision-making; (2) characterize the condition of ecological resources; and (3) report on the progress toward environmental goals through a series of State-of-the-Region reports. These reports are produced using a coordinated, integrated approach that is carried out at four levels of increasing sophistication and complexity. Results indicate that the condition of individual ecological resources can be determined with existing indicators. The results from MAIA are being communicated in a manner that is understood by environmental managers as evidenced by their use in environmental management decision-making. The application of ecological indicators needs to be coupled with an appropriate sampling design to ensure that the measurements made in the environment can be used to address the relevant questions. Multiresource indicators, those that synthesize information on individual ecological resources, are of high priority for research     

Stream ecosystem responses to spatially variable land cover: an empirically based model for developing riparian restoration strategies

1. The restoration of native, forested riparian habitats is a widely accepted method for improving degraded streams. Little is known, however, about how the width, extent and continuity of forested vegetation along stream networks affect stream ecosystems. 2. To increase the likelihood of achieving restoration goals, restoration practitioners require quantitative tools to guide the development of restoration strategies in different catchment settings. We present an empirically based model that establishes a relationship between a ‘stress’ imposed at different locations along a stream by the spatial pattern of land cover within catchments, and the response of biologically determined ecosystem characteristics to this stress. The model provides a spatially explicit, quantitative framework for predicting the effects of changes in catchment land cover composition and spatial configuration on specific characteristics of stream ecosystems. 3. We used geospatial datasets and biological data for attached algae and benthic macroinvertebrates in streams to estimate model parameters for 40 sites in 33 distinct catchments within the mid‐Atlantic Piedmont region of the eastern U.S. Model parameters were estimated using a genetic optimisation algorithm. R² values for the resulting relationships between catchment land cover and biological characteristics of streams were substantially improved over R² values for spatially aggregated regression models based on whole‐catchment land cover. 4. Using model parameters estimated for the mid‐Atlantic Piedmont, we show how the model can be used to guide restoration planning in a case study of a small catchment. The model predicts the quantitative change in biological characteristics of the stream, such as indices of species diversity and species composition, that would occur with the implementation of a hypothetical restoration project.     

Demersal fish assemblages on seamounts exploited by fishing in the Azores (NE Atlantic)

Seamount fish communities are susceptible to variations due to the oceanographic conditions and level of historical fishing effort. In the NE Atlantic, the Azores is considered an “oceanic seamount ecosystem area” because seamount concentration is high relative to other regions. Scientific information on seamounts in the Azores remains scarce and demersal fishery occurs mostly without any knowledge to endorse sustainable harvest strategies. To make available an important baseline information on dynamics of demersal fish populations inhabiting commercially exploited seamounts, the present study has as specific objectives to (a) describe the taxonomic composition of demersal fish assemblages on underwater mountains, (b) examine whether assemblages vary spatial and temporally, and (c) investigate what drives distributional patterns of species in terms of abundance and size composition. For this, three Azorean seamounts (Açores, Princesa Alice and Mar da Prata) exploited by bottom fishing were selected as case study areas. Data were obtained from scientific surveys and commercial fishery over the past c. 25 years. A total of 84 species from 45 families were identified. Sebastidae, Moridae, Sparidae and Centrophoridae were the most abundant families, mainly represented by Helicolenus dactylopterus, Mora moro, Pagellus bogaraveo and Deania profundorum, respectively. Fish assemblages were more distinguishable spatially than temporally. Depth was identified as the main factor responsible for these differences. The higher occurrence of shallow and intermediate (i.e., up to 600 m) habitats in Princesa Alice and Açores seems to favor the occurrence of a greater number of species and higher abundances in comparison to Mar da Prata. Phycis phycis, Pontinus kuhlii, H. dactylopterus, P. bogaraveo, Conger conger and M. moro were the species which primarily contributed to dissimilarities in assemblage structure among sample groups. Abundance indices and fish sizes showed a decreasing trend for many of these species, especially for those with sedentary behaviour inhabiting historically highly exploited seamount areas. These results highlighted the vulnerability of demersal fishes to the expansion of fishing effort in the offshore seamount areas. Spatial management of seamounts should be a priority being fish conservation balanced with strategies that support sustainable fisheries.     

Bathymetric and geographic population structure in the pan-Atlantic deep-sea bivalve Deminucula atacellana (Schenck, 1939)

The deep-sea soft-sediment environment hosts a diverse and highly endemic fauna of uncertain origin. We know little about how this fauna evolved because geographic patterns of genetic variation, the essential information for inferring patterns of population differentiation and speciation are poorly understood. Using formalin-fixed specimens from archival collections, we quantify patterns of genetic variation in the protobranch bivalve Deminucula atacellana, a species widespread throughout the Atlantic Ocean at bathyal and abyssal depths. Samples were taken from 18 localities in the North American, West European and Argentine basins. A hypervariable region of mitochondrial 16S rDNA was amplified by polymerase chain reaction (PCR) and sequenced from 130 individuals revealing 21 haplotypes. Except for several important exceptions, haplotypes are unique to each basin. Overall gene diversity is high (h = 0.73) with pronounced population structure (Phi(ST) = 0.877) and highly significant geographic associations (P < 0.0001). Sequences cluster into four major clades corresponding to differences in geography and depth. Genetic divergence was much greater among populations at different depths within the same basin, than among those at similar depths but separated by thousands of kilometres. Isolation by distance probably explains much of the interbasin variation. Depth-related divergence may reflect historical patterns of colonization or strong environmental selective gradients. Broadly distributed deep-sea organisms can possess highly genetically divergent populations, despite the lack of any morphological divergence.     

Population Structure of Tundra Swans Wintering in Eastern North America

ABSTRACT Our objective was to determine whether there were subpopulations within the eastern population of tundra swans (Cygnus columbianus columbianus) wintering along the mid-Atlantic coast. Movement rates between regions were substantial enough to result in continual mixing of wintering birds. Thus, we were unable to identify distinct subpopulations based on exclusive use of specific wintering areas. These birds should therefore be monitored, and their harvest managed, as if they were one population.