Ecologically Functional Floodplains: Connectivity,Flow Regime,and Scale1

Opperman, Jeffrey J., Ryan Luster, Bruce A. McKenney, Michael Roberts, and Amanda Wrona Meadows, 2010. Ecologically Functional Floodplains: Connectivity, Flow Regime, and Scale. Journal of the American Water Resources Association (JAWRA) 46(2):211-226. DOI: 10.1111/j.1752-1688.2010.00426.x Abstract: This paper proposes a conceptual model that captures key attributes of ecologically functional floodplains, encompassing three basic elements: (1) hydrologic connectivity between the river and the floodplain, (2) a variable hydrograph that reflects seasonal precipitation patterns and retains a range of both high and low flow events, and (3) sufficient spatial scale to encompass dynamic processes and for floodplain benefits to accrue to a meaningful level. Although floodplains support high levels of biodiversity and some of the most productive ecosystems on Earth, they are also among the most converted and threatened ecosystems and therefore have recently become the focus of conservation and restoration programs across the United States and globally. These efforts seek to conserve or restore complex, highly variable ecosystems and often must simultaneously address both land and water management. Thus, such efforts must overcome considerable scientific, technical, and socioeconomic challenges. In addition to proposing a scientific conceptual model, this paper also includes three case studies that illustrate methods for addressing these technical and socioeconomic challenges within projects that seek to promote ecologically functional floodplains through river-floodplain reconnection and/or restoration of key components of hydrological variability.     

The use of bioaccumulation, biomarkers and histopathology diseases in shape Procambarus clarkii to establish bioavailability of Cd and Zn after a mining spill

Individuals of the crayfish Procambarus clarkii (males and females) were exposed simultaneously to cadmium and zinc during 21 days. Exposure concentrations were those determined at the Guadiamar river after the Aznalcóllar mining spill (SW, Spain): 10 and 30 μg L⁻¹ of cadmium and 1000 and 3000 μg L⁻¹ of zinc. Three biomarkers (MT: metallothioneins like proteins, VTG: vitellogenin/vitellin like proteins and histopathology) together with heavy metal bioaccumulation were determined in soft tissues of male and female P. clarkii. At the concentrations tested, increasing cadmium exposure resulted in increasing cadmium bioaccumulation and increasing subletal effects (induction of MT, VTG and histopathological damage in tissues). Nevertheless, although increasing zinc exposure showed increasing VTG induction and histopathological damages, not a positive relationship was determined with MT induction. Concerning to responses determined in male and female crayfishes only differences were found between sexes at the highest cadmium exposure concentration related to bioaccumulation in hepatopancreas tissues. Biomarkers responses to heavy metal contamination in this crayfish, even VTG induction not before tested in heavy metal contamination assessment in crustaceans resulted potential tools for the monitoring of heavy metal environmental contamination.     

Use of contaminated well water, example reference biospheres 1 and 2A

The BIOMASS programme's Theme 1 evaluated a number of scenarios, which assisted in the development of practical guidance. A total of four Example Reference Biospheres were fully developed, with the assumptions, data, and models thoroughly documented. These Examples display both the practicality and the transparency available through the use of the Reference Biosphere Methodology. While the methodology is designed to promote transparency and traceability, proper documentation and justification is still the responsibility of the user. The Examples can also be used as generic analyses in some situations. Although it is anticipated that each of the Reference Biospheres explored within BIOMASS Theme 1 should be a useful practical example, the quantitative results of the model calculations are not intended to be understood as prescribed biosphere 'conversion factors'. In choosing to implement an Example, careful consideration would need to be given to their relevance (including associated data) to the particular assessment context at hand. In general, the more complex the model is, the more limited applicability it has for generic purposes. For example, ERB1A (direct use of well water for drinking) can be used straightforwardly, with minor or no adjustments, at a number of generic sites. Example 2A, however, for which climatic conditions and agricultural practices need to be specified, would need to be implemented for each specific situation.     

Effects of fenoxycarb exposure on complete larval development of the xanthid crab,Rhithropanopeus harrisii

Pest control agents, such as juvenile hormone analogues (JHA), have been developed to limit effects on non-target organisms that co-inhabit insect pest habitats. Rhithropanopeus harrisii, an estuarine xanthid crab, was used to observe the impacts of the JHA, fenoxycarb, on the pattern of complete larval development as well as survival of larvae and successful metamorphosis to first crab stage. Significant mortality occurred in the first of four zoeal stages (after 2-3 days of exposure) at the highest treatment of 240 microg fenoxycarb/l and in megalopae exposed to 48 microg fenoxycarb/l. The time required to metamorphose to the first crab stage was significantly increased for megalopae in all treatments 48 microg/l. This delay in development was sufficient to significantly prolong the entire developmental period from zoea to crabs. Unexposed larvae developed to crabs in an average of 16 days; larvae exposed to >/=48 microg/l required 19-20 days. Reduced survival and extended duration of developing larval stages in the life history of a benthic invertebrate may alter the population dynamics of these organisms in the estuary.     

A harvest failure approach to assess the threat from an invasive species

We present the idea of using potential infringements on annual allowable harvest targets as an approach to estimate threats from invasive species to the forest products sector. The approach uses present-day harvest levels as a reference level to estimate when and where the impact of a nonnative forest pest could become economically damaging. We use a generic model that simulates spread and damage by nonnative invasive species, basic harvest and forest growth through time. The concept is illustrated with a case study of a new nonnative invasive pest, Sirex noctilio Fabricius on pine resources in eastern Canada. Impacts of invasion on wood supply, in particular, the point at which present-day harvest levels are not attainable, were identified for 77 non-overlapping geographical regions that delimit the primary wood supply areas around large mills and wood processing facilities in eastern Canada. The results identify the minimum area of a pest outbreak that could trigger harvest shortages (approximately 12.5–14 M ha of pine forests in Ontario and Quebec). Beyond this level, the amount of host resource available for harvesting in any given year declines rapidly. The failure to sustain broad-scale harvest targets may be an attractive and intuitive indicator for policy makers and regulators interested in developing control and “slow-the-spread” programs for non-native forest pests.     

The influence of an insect growth regulator on the larval development of the mud crab Rhithropanopeus harrisii

Effects of the juvenile hormone analogue (S)-methoprene on the larval development and survival of the estuarine mud crab Rhitrhopanopeus harrisii were examined in the laboratory. Crab leave continuously exposed to 1000 microg (S)-methoprene litre(-1) did not survive beyond zoeal stage I. With continuous exposure to 100 microg (S)-methoprene litre(-1), mortality significantly increased through all larval stages except for zoeal stage II, and developmental duration significantly increased through all zoeal stages but not the premetamorphic megalopa. No supernumerary larval stages occurred with exposure (S)-methoprene. Rhithropanopeus harrisii larvae appear to be more sensitive to the single isomer formulation, (S)-methophrene, than to the double isomer formulation, (S)-methoprene, used in previously documented studies.     

Policy Development for Biodiversity Offsets: A Review of Offset Frameworks

Biodiversity offsets seek to compensate for residual environmental impacts of planned developments after appropriate steps have been taken to avoid, minimize or restore impacts on site. Offsets are emerging as an increasingly employed mechanism for achieving net environmental benefits, with offset policies being advanced in a wide range of countries (i.e., United States, Australia, Brazil, Colombia, and South Africa). To support policy development for biodiversity offsets, we review a set of major offset policy frameworks—US wetlands mitigation, US conservation banking, EU Natura 2000, Australian offset policies in New South Wales, Victoria, and Western Australia, and Brazilian industrial and forest offsets. We compare how the frameworks define offset policy goals, approach the mitigation process, and address six key issues for implementing offsets: (1) equivalence of project impacts with offset gains; (2) location of the offset relative to the impact site; (3) “additionality” (a new contribution to conservation) and acceptable types of offsets; (4) timing of project impacts versus offset benefits; (5) offset duration and compliance; and (6) “currency” and mitigation replacement ratios. We find substantial policy commonalities that may serve as a sound basis for future development of biodiversity offsets policy. We also identify issues requiring further policy guidance, including how best to: (1) ensure conformance with the mitigation hierarchy; (2) identify the most environmentally preferable offsets within a landscape context; and (3) determine appropriate mitigation replacement ratios.     

Mapping forest composition from the Canadian National Forest Inventory and land cover classification maps

Canada's National Forest Inventory (CanFI) provides coarse-grained, aggregated information on a large number of forest attributes. Though reasonably well suited for summary reporting on national forest resources, the coarse spatial nature of this data limits its usefulness in modeling applications that require information on forest composition at finer spatial resolutions. An alternative source of information is the land cover classification produced by the Canadian Forest Service as part of its Earth Observation for Sustainable Development of Forests (EOSD) initiative. This product, which is derived from Landsat satellite imagery, provides relatively high resolution coverage, but only very general information on forest composition (such as conifer, mixedwood, and deciduous). Here we link the CanFI and EOSD products using a spatial randomization technique to distribute the forest composition information in CanFI to the forest cover classes in EOSD. The resultant geospatial coverages provide randomized predictions of forest composition, which incorporate the fine-scale spatial detail of the EOSD product and agree in general terms with the species composition summaries from the original CanFI estimates. We describe the approach and provide illustrative results for selected major commercial tree species in Canada.     

Influence of an insect growth regulator on the larval development of an estuarine shrimp

The influence of methoprene, an insect growth regulator used in mosquito control, on larval development of the estuarine grass shrimp (Palaemonetes pugio) was examined in the laboratory. No grass shrimp larvae successfully completed metamorphosis when continuously exposed to 1000 microg methoprene litre(-1). Completion of larval metamorphosis was significantly reduced by exposure to 100 microg litre(-1) of the isomeric mixture (R,S)-methoprene but not the single isomer formulation (S)-methoprene. No statistically significant difference was revealed, however, in ability to inhibit metamorphosis between these two isomeric types across the broad range of exposure concentrations from 0.1 to 1000.0 microg litre(-1). The first two larval stages and the final premetamorphic larval stage were more sensitive to methoprene toxicity than intermediate larval stages. Methoprene exposure did not alter either the duration of total larval development or the total number of larval stages prior to metamorphosis.     

Individual effects and interactions of salinity,temperature, and zinc on larval development of the grass shrimp Palaemonetes pugio. I. Survival and developmental duration through metamorphosis

Larvae of the estuarine grass shrimp Palaemonetes pugio (Holthuis) were reared from hatch through successful completion of metamorphosis in 80 combinations of salinity (3 to 31%), temperature (20° to 35°C), and zinc (0.00 to 1.00 ppm Zn⁺⁺). Response-surface methodology was employed to depict the individual effects and interactions of the three factors on survival and developmental duration through total larval development. Outside the optimal salinity-temperature conditions of 17 to 27 S and 20° to 27°C, viability of larvae was reduced by both the individual effects of salinity and temperature and interactions between the two factors. Survival capacity of larvae and resistance adaptations to salinity and temperature were progresively reduced by zinc concentrations from 0.25 to 1.00 ppm Zn⁺⁺. Response-surface analysis of the data suggested that the duration of total larval development of P. pugio was least at salinities from 18 to 23 and at temperatures from 30° to 32°C. At both higher and lower salinity-temperature conditions and in increasing zinc concentrations from 0.25 to 1.00 ppm Zn⁺⁺, developmental rates were retarded. A significant zinc-temperature interaction existed, whereby increasing zinc concentrations reduced both survival and developmental rates of larvae more at suboptimal temperatures. Larval resistance to zinc toxicity was least at supraoptimal salinities, indicative of a significant zinc-salinity interaction. The reduced viability, restricted euryplasticity, and retarded developmental rates of P. pugio larvae developing in media with low-level zinc contamination would limit the distributive properties of the pelagic phase in the life cycle of the species and reduce recruitment both into and out of the parent estuarine population.