Summer Projects Areas: Moths and meadows Velocity distributions and fish use of engineered log jam

Moths and Meadows

We have three goals this summer.  One is to continue our work on species distribution models for multiple species.  We have assembled a data set of the presence/absence of 422 species of moths measured at 256 sites in the HJ Andrews Forest.  We seek to create a statistical/machine learning model that predicts which moth species will be present/absent at all locations throughout the forest. The model will take as input variables describing a site (e.g., vegetation, elevation, etc.) and predict the species that will be found there.  We are particularly interested in discovering which species co-occur and which are mutually exclusive.  We have found that different machine learning algorithms produce models with very different levels of accuracy, and we want to understand why this is so.

Our current data lack important information about the site variables, so the field component of this study will be to measure a variety of variables at as many of the sites as possible.  The field surveys will focus on quantifying the presence and abundance of a set of host plants where moth caterpillars are known to feed; many of these host plants are species-specific.  An important factor influencing moth populations is the difference between conifer/evergreen and broadleaf/deciduous vegetation.  The results of this field survey should allow us to make our model much more accurate.  Also, moths are important food sources for birds in the Andrews Forest landscape. Hence, these field surveys will also help with other modeling efforts at the HJA, especially models of bird behavior.

The second goal is to model what conditions can predict the "flight time" of moths--that is, the date when they first emerge and start flying.  Our main hypothesis is that flight time is determined by the integrated energy (e.g., temperature degree days) received by the forest.  When the total energy exceeds some (unknown) threshold, we predict the moths will fly.  We want to test this and several other hypotheses, because of the implications for how moths will respond to global warming.  We have similar data for bird migration, and we would like to fit similar models to predict spring arrival dates and autumn departure dates for migratory species.  What factors determine these dates?  How much do they vary across species?  Do the dates reflect competition for food? nesting sites? mating opportunities?  This work will build on existing datasets at the Andrews Forest, such as climate variables and geographical information (like elevation, vegetation cover, temperature, precipitation, wind, humidity) but will also use field data collected about moth host plants.

The third goal is to build mathematical models to understand how the dispersal behaviors of moths and birds affect the data that we collect on presence/absence.  When we place an observer at location x and a bird has a nest at location y, what is the probability that the observer will detect the bird?  How does this vary with the distance between x and y?  Analogous questions arise for moths.  When we measure site variables at x rather than at y, what problems does this cause for fitting species distribution models?  Mathematical models also can address the question of how moths (or birds) select habitat locations.  These models will use applied probability approaches.

Velocity distributions and fish use of engineered log jams

Project mentors:  Desiree Tullos (Biological and Ecological Engineering), Eugene Zhang (Computer science), and Matt Cox (Biological and Ecological Engineering)

Increases in human population and industrial, commercial, and residential development have placed heavy demands on stream corridors at the expense of healthy streams and riverine ecosystems. Traditional engineering responses to accommodate development (i.e. flood control) have failed to incorporate natural river processes, riparian functions or aesthetic value and consequently have led to degraded streams and aquatic ecosystems. In an effort to restore streams and improve declining fish populations, stream restoration has taken center stage for fisheries management. Streambank stabilization is often implemented at river bends where natural vegetation has been removed and the streambank is eroding, causing both instream habitat degradation and land use concerns. Streambank stabilization projects are increasingly required to use natural materials (e.g. wood) as opposed to traditional engineering methods (riprap) because natural materials are thought to provide more natural habitat for fish and aquatic organisms, have esthetic appeal, are more easily permitted, and are often available locally. However, questions remain regarding the effectiveness of these Engineered Log Jams (ELJs) in both providing habitat and stabilizing streambanks, primarily due to lack of direct observations of fluid mechanics around and fish use of these engineered structures.
Regarding fluid mechanics, there are two primary flow patterns to consider when designing stream bank stabilization structures at meander bends: helicoidal flow and cross stream flow. A meander bend experiences one or both of these flow forces depending on its radius of meander curvature and its channel width at bankfull flow. When both types of flow are present, the force of the flow applied to the stream bank is stronger and originate from multiple directions, resulting in greater outward erosion. Meander bends experiencing different flow forces require different types and configurations of streambank stabilization structures, however current stabilization efforts often fail to consider the difference during the design process.
Efforts are also hindered by the limited knowledge on how fish and aquatic organisms respond to different flow forces and how they use streambank stabilization structures and engineered habitats. This makes designing and gauging the ecological success of these structures very difficult. Concern has increased over recoveries of ESA-listed salmon species in the Pacific Northwest and new regulations in Oregon explicitly prohibit the use of rock and encourage bioengineering and the use of wood in all streambank stabilization projects. Understanding the effects of stream restoration actions on stream processes and stream ecology is important in improving the engineering and design of streambank stabilization.

       Snorkel surveys in Quartz Creek                                            Velocity measurements in Quartz Creek

Objectives
1.  Investigate flow forces at meander bends at different types and configurations of engineered log jams by measuring velocity distributions.
2.  Compare fish use of habitats in different types of meander bends in natural and engineered wood jams.
3.   Evaluate how velocity distributions (helicoidal verses cross stream flow) and changes in flow depth are related to fish density and behavior in structures.

Hypotheses     
1.  The strength and orientation of flow fields will vary with location and configuration of the structures. Flow fields for structures at the upstream end of the meander bend will be dominated by helicoidal flow, while structures at the downstream end of the meander will experience both helicoidal and cross stream flows. Differences in the spacing and configuration (e.g. size, roughness, protrusion) of wood structures will influence the strength and orientation of flow fields.
2.  Fish species behavior and density will differ at meander bends under different flow forces (helicoidal verses cross stream flow) and will change spatially and temporally under different flow conditions. Fish will use structures for feeding at lower flows, orienting their bodies in the direction of the strongest flow fields. During higher flows, fish will utilize structures for cover and refugia, orienting their bodies against the strongest flow fields. Fish will preferentially utilize certain structures based on the structure configuration and location along the meander.

Methods

Summer 2013 activities

Students will work on a broad, interdisciplinary team that includes two high school students, three undergraduate students, a graduate student, a faculty research assistant, and an associate professor. Supported by this team, students will work on one of several research tasks that contributes to the broader goals of the project, including:  

· Engineering, ecology, or earth science student: Use VidSync or Photosynth (or similar program) to map out the root wad from photos paired with surveys, ADV positions and horizontal ADV boundary distances.

·Engineering student: Estimate and visualize force distribution on engineered log jams based on velocity       profiles· Computer science student: Interpretation of the flow field applying tensor visualization techniques

·Engineering, ecology or earth science student: Collect Digital Particle Image Velocimetry (DPIV)             images and movies of salmon in raceways

          ·Ecology student: VidSync transcription- Identify focal point coordinates for individual fish and map to
             velocity measures at that coordinate

· Ecology student: VidSync transcription- General description (general locations, time spent there, evidence of aggression or foraging, etc.) of all behaviors for observed fish.

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