Invasive rat establishment and changes in small mammal populations on Caribbean Islands following two hurricanes

Invasive mammals, particularly black rats (Rattus rattus), house mice (Mus musculus), and mongoose (Herpestes auropunctatus) are established on many tropical islands and threaten natural resources such as native birds, sea turtles, lizards, invertebrates, and plants. St. Croix (U.S. Virgin Islands, Caribbean) has a diversity of natural resources being protected from invasive mammals by U.S. conservation agencies. Sandy Point National Wildlife Refuge and Buck Island Reef National Monument receive among the highest density of nesting sea turtles in the region, including annual nesting populations of 50e250 leatherbacks (Dermochelys coriacea), 25e80 hawksbills (Eretmochelys imbricata), and 100e250 green turtles (Chelonia mydas). Buck Island Reef National Monument and Green Cay National Wildlife Refuge are small islands near St. Croix Island that have endangered St. Croix ground lizards (Ameiva polops) established. Rodents and mongoose threaten each of these natural resources. The goal of our study was to determine the types of small mammals (i.e., mongoose, rats, and/or house mice) that are established in each of the three hotspot locations mentioned, and to determine how two severe hurricanes (Irma and Maria) affected the small mammal populations. We used traps and tracking tunnels, which are baited ink cards placed in tunnels so that animal foot prints can be identified, to determine presence and relative abundances of small mammal species. We found that: 1) black rats invaded and established, possibly by rafting and/or swimming, Green Cay following the hurricanes, 2) house mice, rats, and mongoose were present before and after the hurricanes at Sandy Point (mice had not been documented prior to our sampling), and house mouse abundance significantly increased (\u3e2.5 times pre-hurricane levels) 9-months after the hurricanes, and 3) the house mouse population more than doubled 15-months after the hurricanes on Buck Island. Land and resource managers benefit from knowing the composition and relative abundances of the small mammal communities, and the presence of house mice will make predator-free management efforts challenging. Surveillance using tracking tunnels enables rapid confirmation of new invasive species in isolated habitats and following large storms, as demonstrated by our finding that black rats established on Green Cay following the 2017 hurricanes

Spatial and temporal patterns of coral bleaching around Buck Island Reef National Monument, St. Croix, U.S. Virgin Islands [poster]

Limited information currently exists on the recovery periods of bleached corals as well as the spatial extent, causative factors, and the overall impact of bleaching on coral reef ecosystems. During October, 2005, widespread coral bleaching was observed within Buck Island Reef National Monument (BUIS) St. Croix, USVI. The bleaching event was preceded by 10 weeks of higher than average water temperatures (28.9-30.1°C). Random transects (100 square meters) over hard bottom habitats (N=94) revealed that approximately 51% of live coral cover was bleached. Nineteen of 23 coral species within 16 genera and two hydrocoral species exhibited signs of bleaching; species-specific bleaching patterns were variable throughout the study area. Coral cover for Montastraea annularisand species of the genus Agariciawere the most affected, while other species exhibited variability to bleaching. Although a weak but significant negative relationship (r2=0.10, P=0.0220) was observed, bleaching was evident at all depths (1.5-28 m). Bleaching was spatially autocorrelated (P=0.001) and hot-spot analysis identified a cluster of high bleaching stations northeast of Buck Island. Bleaching was significantly reduced within all depth zones and habitat types upon subsequent monitoring during April (15%) and October (3%) 2006

Spatial and temporal patterns of coral bleaching around Buck Island Reef National Monument, St. Croix, U.S. Virgin Islands

Since 2001, biannual fish and habitat monitoring has been conducted for the shallow (> 30 m), colonized pavement and gorgonian dominated Buck Island Reef National Monument (BIRNM) St. Croix, USVI and adjacent waters. during October, 2005, widespread coral bleaching was observed within the ∼50 square-kilometer study area that was preceded by 10 wks of higher than average water temperatures (28.9–30.1 °C). Random transects (100 square meters) were conducted on linear reefs, patch reefs, bedrock, pavement, and scattered coral/rock habitats during October 2005, and April and October 2006, and species specific bleaching patterns were documented. During October 2005 approximately 51% of live coral cover was bleached. Nineteen of 23 coral species within 16 genera and two hydrocoral species exhibited signs of bleaching. Coral cover for Montastraea annularis and species of the genus Agaricia were the most affected, while other species exhibited variability in their susceptibility to bleaching. Bleaching was evident at all depths (1.5–28 m), was negatively correlated with depth, and positively correlated with habitat complexity. Bleaching was less prevalent at all depths and habitat types upon subsequent monitoring during April (15%) and October (3%) 2006. Four species and one genus did not exhibit signs of bleaching throughout the study period (Dendrogyra cylindrus, Eusmilia fastigata, Mussa angulosa, Mycetophyllia aliciae, Scolymia spp.)

Status of coral reef ecosystems in a marine managed area in St. Croix, USVI [poster]

This poster presents information on the status and trends of coral reef ecosystems in St. Croix, US Virgin Islands (USVI). Data were collected by NOAA’s Center for Coastal Monitoring and Assessment Biogeography Branch (CCMA-BB) from 2001-2006 at 1,275 random locations in and around Buck Island Reef National Monument (BIRNM). The main objective was to quantify changes in fish species and assemblage diversity, abundance, biomass and size structure; to provide spatially explicit information on the distribution of key species or groups of species; and to compare community structure inside versus outside of BIRNM

Testing methods to mitigate Caribbean yellow-band disease on Orbicella faveolata

Outbreaks of coral diseases continue to reduce global coral populations. In the Caribbean, yellow band is a severe and wide-spread disease that commonly affects corals of the Orbicella spp. complex, significantly impeding coral reproduction, and hindering the natural recovery of Orbicella spp. populations. Caribbean yellow-band disease (CYBD) lesions may be severe, and often result in the complete loss of coral tissue. The slow spread of CYBD, however, provides an opportunity to test methods to mitigate the disease. Here we report the results of in situ experiments, conducted within Buck Island Reef National Monument in St. Croix, USVI, to test the effectiveness of three techniques to minimize disease impact on Orbicella faveolata: (1) shading, (2) aspirating, and (3) chiseling a “firebreak” to isolate the lesion. Neither shading nor aspirating the diseased tissue significantly reduced CYBD tissue loss. However, chiseling reduced the rate and amount of tissue lost by 31%. While 30–40% of the chiseled lesions appeared to be free of disease signs 12–16 months after treatment, success significantly and steadily declined over 23 months, indicating a possible lack of long-term viability of the technique. The results of this study demonstrate that creating a “firebreak” between diseased and healthy- appearing tissue slows the spread of the disease and may prolong the life of O. faveolata colonies. The firebreak method yielded the best results of all the techniques tested, and also required the least amount of effort and resources. However, we do not recommend that this treatment alone be used for long-term disease mitigation. Rather, we propose that modifications of this and other treatment options be sought. The results also highlight the need for extended monitoring of CYBD after any treatment, due to the slow but variable rate and pattern of tissue loss in this disease

Testing methods to mitigate Caribbean yellow-band disease on Orbicella faveolata

Outbreaks of coral diseases continue to reduce global coral populations. In the Caribbean, yellow band is a severe and wide-spread disease that commonly affects corals of the Orbicella spp. complex, significantly impeding coral reproduction, and hindering the natural recovery of Orbicella spp. populations. Caribbean yellow-band disease (CYBD) lesions may be severe, and often result in the complete loss of coral tissue. The slow spread of CYBD, however, provides an opportunity to test methods to mitigate the disease. Here we report the results of in situ experiments, conducted within Buck Island Reef National Monument in St. Croix, USVI, to test the effectiveness of three techniques to minimize disease impact on Orbicella faveolata: (1) shading, (2) aspirating, and (3) chiseling a “firebreak” to isolate the lesion. Neither shading nor aspirating the diseased tissue significantly reduced CYBD tissue loss. However, chiseling reduced the rate and amount of tissue lost by 31%. While 30–40% of the chiseled lesions appeared to be free of disease signs 12–16 months after treatment, success significantly and steadily declined over 23 months, indicating a possible lack of long-term viability of the technique. The results of this study demonstrate that creating a “firebreak” between diseased and healthy-appearing tissue slows the spread of the disease and may prolong the life of O. faveolata colonies. The firebreak method yielded the best results of all the techniques tested, and also required the least amount of effort and resources. However, we do not recommend that this treatment alone be used for long-term disease mitigation. Rather, we propose that modifications of this and other treatment options be sought. The results also highlight the need for extended monitoring of CYBD after any treatment, due to the slow but variable rate and pattern of tissue loss in this disease

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

The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2002

Called for by the U.S. Coral Reef Task Force’s (USCRTF) National Action Plan to Conserve Coral Reefs, this is the first biennial report on the condition of coral reefs. It is the scientific baseline for subsequent reports on the health of U.S. coral reef ecosystems that are to be used by NOAA and others to evaluate the efficacy of coral reef conservation and management practices. The National Oceanic and Atmospheric Administration’s National Ocean Service led the development of this report. It was authored by 38 experts and supported by 79 contributors from government agencies and non-governmental organizations across the nation and internationally. Over 100 Task Force members and other notable scientists have reviewed this document

Invasive rat establishment and changes in small mammal populations on Caribbean Islands following two hurricanes

Invasive mammals, particularly black rats (Rattus rattus), house mice (Mus musculus), and mongoose (Herpestes auropunctatus) are established on many tropical islands and threaten natural resources such as native birds, sea turtles, lizards, invertebrates, and plants. St. Croix (U.S. Virgin Islands, Caribbean) has a diversity of natural resources being protected from invasive mammals by U.S. conservation agencies. Sandy Point National Wildlife Refuge and Buck Island Reef National Monument receive among the highest density of nesting sea turtles in the region, including annual nesting populations of 50e250 leatherbacks (Dermochelys coriacea), 25e80 hawksbills (Eretmochelys imbricata), and 100e250 green turtles (Chelonia mydas). Buck Island Reef National Monument and Green Cay National Wildlife Refuge are small islands near St. Croix Island that have endangered St. Croix ground lizards (Ameiva polops) established. Rodents and mongoose threaten each of these natural resources. The goal of our study was to determine the types of small mammals (i.e., mongoose, rats, and/or house mice) that are established in each of the three hotspot locations mentioned, and to determine how two severe hurricanes (Irma and Maria) affected the small mammal populations. We used traps and tracking tunnels, which are baited ink cards placed in tunnels so that animal foot prints can be identified, to determine presence and relative abundances of small mammal species. We found that: 1) black rats invaded and established, possibly by rafting and/or swimming, Green Cay following the hurricanes, 2) house mice, rats, and mongoose were present before and after the hurricanes at Sandy Point (mice had not been documented prior to our sampling), and house mouse abundance significantly increased (\u3e2.5 times pre-hurricane levels) 9-months after the hurricanes, and 3) the house mouse population more than doubled 15-months after the hurricanes on Buck Island. Land and resource managers benefit from knowing the composition and relative abundances of the small mammal communities, and the presence of house mice will make predator-free management efforts challenging. Surveillance using tracking tunnels enables rapid confirmation of new invasive species in isolated habitats and following large storms, as demonstrated by our finding that black rats established on Green Cay following the 2017 hurricanes

The successful eradication of introduced roof rats (\u3ci\u3eRattus rattus\u3c/i\u3e) from Buck Island using diphacinone, followed by an irruption of house mice (\u3ci\u3eMus musculus\u3c/i\u3e)

The United States National Park Service and the United States Wildlife Services made a planned and sustained effort to eradicate the introduced roof rats (Rattus rattus) from Buck Island Reef National Monument in the Caribbean Sea during 1998–2000. The rats were causing substantial damage to a variety of the 80-ha island’s floral and faunal resources. An island-wide grid of elevated bait stations containing anticoagulant (0.005% diphacinone; 50 ppm) rodenticide bait blocks were used to eradicate the rats. The bait stations were modified several times to assure ready access by rats while minimizing access by non-target animals, especially crabs and birds. Numerous post-project trapping sessions over six years resulted in no rat captures, suggesting that, indeed, the rats had been eradicated from the island. No non-target losses resulting from the baiting program were observed by field personnel, but they noted what appeared to be a recovery of some of the island’s floral and faunal resources. There have been no depredations of endangered sea turtle nests since the eradication. Post-project monitoring sessions revealed the presence of a growing house mouse (Mus musculus) population on the island. The threats posed by, and potential management strategies for, this introduced pest species are being investigated. This is the first successful rat eradication on a sizable island, using diphacinone bait blocks with a unique, elevated bait-station system. Diphacinone can provide an alternative to the highly toxic brodifacoum and may help reduce non-target hazards in some situations, although several applications are generally required