Comparing the efficiency of biodiversity monitoring programs

Monitoring is a crucial tool for measuring the progress and success of environmental policies and management programs. While many studies have evaluated the effectiveness of biodiversity sampling methods, few have compared the cost-efficiency of such sampling methodologies, which is a key attribute of a good monitoring program. There is a particular need for better understanding the relationship between cost and performance of biodiversity monitoring strategies in the marine environment, where monitoring and management programs have a shorter history and data collection can be exceptionally expensive. In this study we have developed a method to i) assess the optimum sampling effort required to assess biodiversity of shallow nearshore fish communities and ii) compare the efficiency of different fish biodiversity monitoring methods. We analyzed data from fish surveys performed in the Santa Barbara Channel, including belt transects conducted by scientists at the Partnership for Interdisciplinary Studies of Coastal Oceans, similar surveys conducted by citizen scientists in the Reefcheck monitoring programs, and roving diver data collected by the Channel Islands National Park’s Kelp Forest Monitoring Project. We constructed efficiency curves describing how diversity estimates and associated confidence changed as a function of effort for each program for a variety of diversity estimators (⁰D, ¹D and ²D rarified to 100). We found that the three programs produced very similar measurements of species diversity despite substantial differences in the list of species counted by each method. The uncertainty of the diversity estimations greatly decreases after one hour of diving, with confidence increasing faster and reaching a higher level for the roving diver method. Strikingly, the citizen-science method performed almost identically to the more professional belt-transect method, highlighting the potential value of these alternative monitoring methods. Although we illustrate these methods for evaluating sampling efficiency with fish data, they are applicable to a range of methods and contexts, and can guide the management decisions in relation to optimizing the resources available in biodiversity monitoring programs.