Trend and power analysis for National Park Service marine data from 2006 to 2010: Pacific Island Network
Harrod Sarcevich LA. 2013. Trend and power analysis for National Park Service marine data from 2006 to 2010: Pacific Island Network. Natural Resource Technical Report. NPS/PACN/NRTR—2013/771. National Park Service. Fort Collins, Colorado
Marine monitoring data collected in Kalaupapa National Historical Park (KALA) and Kaloko-Honokohau National Historical Park (KAHO) between 2006 and 2010 provide the basis for a trend analysis and subsequent power analysis. Trends are estimated from the monitoring data with a t-test derived from a linear mixed model which combines fixed effects for status and trend with random effects with variance components to describe year-to-year variation, site-to-site variation, and variation among site-level slopes. Data transformation such as the log, logit, and arc-sine square-root transformation were used to meet linear modeling assumptions. Two-sided trend tests conducted at the 0.10 level indicate significant trends in KAHO turf algae percent cover (p-value = 0.0448) and KALA rugosity (p-value = 0.0199). Future trend modeling may be improved by incorporating covariate information to explain variation and improve the precision of trend estimators. Power simulations were conducted for Type I error rates of 0.05 and 0.10 and annual increasing trends of 1%, 2%, and 4%. A Monte Carlo power simulation was run for each outcome of interest, park, trend, and Type I error rate. Monet Carlo power simulations incorporate fixed effects estimates of status and estimated variance components to generate similar populations that exhibit a known trend. The power to detect a given trend is calculated as the proportion of times a two-sided trend test is significant at the given Type I error rate for the set of 500 simulated sampled populations. The sampling design used for the simulation is the rotating panel design of 15 annually-visited sites and 15 randomly-selected sites that is used in the monitoring program. Coral percent cover, rugosity, and fish species richness demonstrate the highest power to detect trend across parks. Annual trends in rugosity and fish species richness of 1%, 2%, or 4% can be detected with at least 80% power in KALA within 10 years. In KAHO, moderate (2%) to large (4%) annual trends in rugosity and turf algae cover can be detected within the same time frame. These indicators may be useful for early detection of trends.
- Type
- Published Report
- Authors
- Harrod Sarcevich, Leigh
- Date of Issue
- 2013-06
- Publisher
- National Park Service
- Units
- KAHO , KALA , NRSS , PACN
- Keywords
- benthic marine communities, Benthic Marine Monitoring, Coral, coral rugosity, coral settlement, Coralline algae, fish biomass, fish density, fish species richness, macro-algae, Macroinvertebrates, Marine Fish, Marine Fish Monitoring Report, power analysis, trend modelling, turf algae
- Subjects
- Ecological Framework: Biological Integrity | Focal Species or Communities | Marine Communities , Ecological Framework: Biological Integrity | Focal Species or Communities | Marine Invertebrates , Ecological Framework: Biological Integrity | Focal Species or Communities | Fishes