Evaluation and Proposed Refinement of the Sampling Design for the Long Term Resource Monitoring Program's Fish Component
Abstract : Environmental monitoring programs are frequently designed to track changes in key physical, chemical, and biological features of an ecosystem. As such, these programs provide critical information for detecting changes in system state, investigating causal mechanisms of the observed changes, and making resource management decisions. Because monitoring programs require significant investments of time, money, and human resources to implement and maintain, periodic evaluations of monitoring programs are necessary to determine if the sampling design adequately addresses program goals and objectives. Periodic evaluations also permit assessment of a program's ability to provide adequate and useful information for changing management and science needs. We evaluated the Long Term Resource Monitoring Program's (LTRMP) fish sampling design by analyzing data from stratified random samples collected from 1993 to 1999 in six Trend Analysis Areas (TAAs). Specifically, we investigated whether the sampling design could provide similar information with fewer sampling gears. Our goals were to identify and quantify information provided by each gear used to monitor fish in the LTRMP, develop alternative sampling design scenarios based on our analyses and expert opinion, and engage program partners in a discussion on the relative value of each gear within the present sampling design. Community characterization (presence or absence), community structure (relative abundance within the full community), and detection of annual changes in single-species catch-per-unit-effort (Lubinski et al. 2001) are the primary information provided by the fish component. Our analyses considered differences in these measures among TAAs, gear types, sampling strata, seasonal sampling period, and fish size. Results were made available to program partners through a Web site for review and comment. Based on these analyses, program partners developed a suite of potential options for component refinement.
Influence of local-scale abiotic and biotic factors on stress and nutrition in invasive silver carp
Community structure and dynamics in aquatic ecosystems are influenced by a variety of abiotic and biotic factors including productivity, species composition, and temperature. These factors may also affect local-scale community resilience to nonnative species invasions. We used habitat characteristics, zooplankton concentrations, fish abundances, and species composition and richness data collected by two fish population monitoring programs to define relationships that influence stress and nutrition in invasive silver carp (Hypophthalmichthys molitrix). We collected blood samples and quantified nutritional (alkaline phosphatase, cholesterol, protein, and triglycerides) and stress metrics (cortisol and glucose) from individuals across three distinct time periods. Nutritional patterns in silver carp were explained by temperature and food resources, indicating elevated feeding in warmer months. Patterns in blood-based stress parameters were most strongly driven by environmental characteristics, elevating with high water temperatures and increased turbidity. Nutrient levels and community richness parameters did not influence the stress or condition of silver carp, likely due to the absence of limiting resources or competition for this species. Together, our results provide insights into the factors that may influence the spread and distribution of silver carp, as well as the characteristics of habitats that could be vulnerable to future silver carp invasion.
SEASONAL AND REGIONAL MPG AS INFLUENCED BY ENVIRONMENTAL CONDITIONS AND TRAVEL PATTERNS
In-use fuel economy shortfall varies regionally and seasonally in response to changing environmental conditions and travel patterns. Shortfall changes by 25 percent or more are associated with variation in miles travelled per day by in-use vehicles. Monthly variations in northern states are twice those in the south; air conditioning penalties also vary by region. Although regional difference in annual levels are relatively small, shortfall can increase by 16 percent in densely populated urban areas. These variations have been quantified in an analysis of time-series mpg data and related to variables commonly reported in fuel economy surveys.