Space Use and Relative Habitat Selection for Immature Green Turtles Within a Caribbean Marine Protected Area

Background A better understanding of sea turtle spatial ecology is critical for the continued conservation of imperiled sea turtles and their habitats. For resource managers to develop the most effective conservation strategies, it is especially important to examine how turtles use and select for habitats within their developmental foraging grounds. Here, we examine the space use and relative habitat selection of immature green turtles (Chelonia mydas) using acoustic telemetry within the marine protected area, Buck Island Reef National Monument (BIRNM), St. Croix, United States Virgin Islands. Results Space use by turtles was concentrated on the southern side of Buck Island, but also extended to the northeast and northwest areas of the island, as indicated by minimum convex polygons (MCPs) and 99%, 95%, and 50% kernel density estimations (KDEs). On average space use for all categories was \u3c 3 km2 with mean KDE area overlap ranging from 41.9 to 67.7%. Cumulative monthly MCPs and their proportions to full MCPs began to stabilize 3 to 6 detection months after release, respectively. Resource selection functions (RSFs) were implemented using a generalized linear mixed effects model with turtle ID as the random effect. After model selection, the accuracy of the top model was 77.3% and showed relative habitat selection values were highest at shallow depths, for areas in close proximity to seagrass, and in reef zones for both day and night, and within lagoon zones at night. The top model was also extended to predict across BIRNM at both day and night. Conclusion More traditional acoustic telemetry analyses in combination with RSFs provide novel insights into animal space use and relative resource selection. Here, we demonstrated immature green turtles within the BIRNM have small, specific home ranges and core use areas with temporally varying relative selection strengths across habitat types. We conclude the BIRNM marine protected area is providing sufficient protection for immature green turtles, however, habitat protection could be focused in both areas of high space use and in locations where high relative selection values were determined. Ultimately, the methodologies and results presented here may help to design strategies to expand habitat protection for immature green turtles across their greater distribution

Friction compensation using Coulomb friction model with zero velocity crossing estimator for a force controlled model in the loop suspension test rig

This paper presents a method of friction compensation for a linear electric motor in a model in the loop suspension test rig. The suspension consists of a numerically modeled spring and damper, with inputs of suspension motion. The linear motor is force controlled using a force sensor to track the output of the numerical model. The method uses a Coulomb friction model and applies a feedforward step signal when velocity zero crossing occurs. Velocity zero crossing estimation is achieved using an algorithm based on measured feedback velocity and force. Experimental results indicate reduction of force tracking error caused by Coulomb friction leading to improved test rig accuracy. </jats:p

Validating a Wave-to-Wire Model for a Wave Energy Converter—Part I: The Hydraulic Transmission System

Considering the full dynamics of the different conversion stages from ocean waves to the electricity grid is essential to evaluate the realistic power flow in the drive train and design accurate model-based control formulations. The power take-off system for wave energy converters (WECs) is one of the essential parts of wave-to-wire (W2W) models, for which hydraulic transmissions are a robust solution and offer the flexibility to design specific drive-trains for specific energy absorption requirements of different WECs. The potential hydraulic drive train topologies can be classified into two main configuration groups (constant-pressure and variable-pressure configurations), each of which uses specific components and has a particular impact on the preceding and following stages of the drive train. The present paper describes the models for both configurations, including the main nonlinear dynamics, losses and constraints. Results from the mathematical model simulations are compared against experimental results obtained from two independent test rigs, which represent the two main configurations, and high-fidelity software. Special attention is paid to the impact of friction in the hydraulic cylinder and flow and torque losses in the hydraulic motor. Results demonstrate the effectiveness of the models in reproducing experimental results, capturing friction effects and showing similar losses

Status Of Coral Reefs In The U.S. Caribbean And Gulf Of Mexico: Florida, Flower Garden Banks, Puerto Rico, U.S. Virgin Islands, Navassa.

Mapping, monitoring, and management of coral reefs of Florida, the Flower Garden Banks National Marine Sanctuary (FGBNMS) northwestern Gulf of Mexico, Puerto Rico, U.S. Virgin Islands and Navassa have all improved with increased awareness and funding from the Government of the USA. Quantitative baseline surveys of coral reef communities have been completed in Puerto Rico at three current or proposed Natural Reserves. Monitoring is demonstrating trends in reef community health and structure in other sensitive coastal areas. The Tres Palmas Marine Reserve has been designated recently, and existing MPAs and revisions to fishing laws were evaluated based on these results. In the U.S. Virgin Islands (USVI), the Buck Island Reef National Monument has been expanded and a new park, the St. Croix East End Marine Park established in 2003. The monitoring programs in the USVI are now detecting changes in fish and coral community structure in and around the managed areas with a specific focus on elkhorn coral stands. Monitoring of water quality, reef diversity, growth, and populations of dominant fish and benthic organisms in Flower Garden Banks, Stetson Bank, and Navassa has assisted in evaluating impacts of climate change, tropical storms, fishing, and tourism pressures. An expanded Florida monitoring program is now completing the first integrated assessment of the reefs northwards from the Florida Keys. It is hoped that this increased attention to coral reef issues will continue, and that advances in the understanding of how coral reef ecosystems respond to anthropogenic stresses will result in better management plans that protect coastal resources by reducing those stresses. However, an improved understanding of the relative importance of how stresses contribute to or cause coral decline is needed. There is a need also to understand the linkages between water flows and the functioning of coral reef ecosystems. It is essential to strengthen cross-boundary and cross-jurisdictional agreements to facilitate ecosystem-based management and information and technology transfer