This study investigated the potential effects of red tide events (blooms of the toxin-producing dinoflagellate,
Karenia brevis
) on Atlantic tarpon (
Megalops atlanticus
), a long-lived migratory ...game fish, along the southwestern coast of Florida. In this region, red tides have long been associated with mass mortality events of marine organisms and other deleterious effects on coastal ecosystems. To estimate the impacts of red tide on tarpon and the recreational fishery they support, we used a mixed-methods approach that combined multiple data sources including fish kill data, local ecological knowledge (LEK) interviews, angler catch logs, and acoustic telemetry. Our results suggested tarpon are somewhat tolerant to red tide blooms; but, when blooms did overlap with tarpon peak abundance and became dense and large, tarpon were reported to leave the affected area, suffered mortality, or both. Furthermore, in recent years, LEK data suggested an increase in the persistence and overlap of red tide blooms with peak tarpon abundance that coincided with their spawning season. In contrast, using acoustic telemetry data, we did not detect any pattern in tarpon presence during red tide events, further suggesting that tarpon may be adaptive to the effects of red tide. Finally, to evaluate monitoring methods, data quality, and collection, we used a strengths, weaknesses, opportunities, and threats analysis and found all could be improved through increased engagement with LEK and collaboration among researchers. Ultimately, combining multiple data sources helped elucidate how red tide exposure influences tarpon and the recreational fishery that targets them.
Bonefish (
Albula
spp.) are a popular target for recreational anglers practicing primarily catch-and-release (C&R). The effects of C&R on bonefish have been previously examined in subtropical regions ...of The Bahamas. However, it is unclear how these findings relate to larger bonefish, as well as those caught in warmer, tropical environments. Here we examined the effects of C&R on physiological stress and reflex impairment in bonefish in tropical Culebra, Puerto Rico. Bonefish (
Albula vulpes
; 56.6 ± 5.0 cm total length, mean ± SE) were angled with spinning or fly fishing gear and either handled entirely in the water without air exposure (
n
= 12) or exposed to air for 2 min to simulate an aerial hook removal and admiration period (
n
= 11). Upon capture, bonefish were assessed for the presence of five reflexes and held in floating net pens for 1 h prior to phlebotomy for quantification of physiological stress. Blood lactate and pH were correlated with fight time, but linear models showed air exposure and water temperature were better predictors of physiological stress. Compared to previous research using simulated angling events, larger bonefish in warmer water under true angling scenarios had similar physiological stress responses. Two minutes of air exposure caused significant reflex impairment, which is a strong predictor of post release behavioural impairment and mortality risk in this species. Air exposure should be avoided with bonefish, especially with larger fish and at warmer water temperatures to minimize negative impacts and ensure the sustainability of C&R bonefish angling.
The Caribbean bonefish species
Albula vulpes
is an economically important nearshore marine sport fish that has notably declined in the Florida Keys over the past 20–30 years. The reasons for this ...decline are unclear, although habitat loss, water quality reductions, climate change, and other environmental drivers likely play a role. Infectious disease can also cause precipitous species-specific declines in wildlife populations, but virtually nothing is known about infection in bonefish. We analyzed communities of bacteria on the gills of bonefish from the Florida Keys, where declines are pronounced, and the islands of Eleuthera and Inagua in The Bahamas, where no such declines have been recorded. Bacterial community composition varied significantly among island location (Keys, Eleuthera, Inagua) and among sites within island locations (e.g., tidal creeks, coves, inlets). Seventeen times more bacterial taxa were over-represented in the Florida Keys than in The Bahamas, and several bacterial genera over-represented in the Florida Keys have been linked to environmental contamination and disease (e.g.,
Corynebacterium
;
Acholeplasma
;
Staphylococcus
; and
Streptococcus
). These results show that gill bacterial community signatures may prove useful for investigating bonefish spatial ecology and that communities of microbes on bonefish gills contain differentially abundant and potentially pathogenic bacteria that covary with the overall “health” of the population.
Abstract
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 < 3 km
2
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.
Resource selection functions (RSFs) have been widely applied to animal tracking data to examine relative habitat selection and to help guide management and conservation strategies. While readily used ...in terrestrial ecology, RSFs have yet to be extensively used within marine systems. As acoustic telemetry continues to be a pervasive approach within marine environments, incorporation of RSFs can provide new insights to help prioritize habitat protection and restoration to meet conservation goals. To overcome statistical hurdles and achieve high prediction accuracy, machine learning algorithms could be paired with RSFs to predict relative habitat selection for a species within and even outside the monitoring range of acoustic receiver arrays, making this a valuable tool for marine ecologists and resource managers. Here, we apply RSFs using machine learning to an acoustic telemetry dataset of four shark species to explore and predict species-specific habitat selection within a marine protected area. In addition, we also apply this RSF-machine learning approach to investigate predator-prey relationships by comparing and averaging tiger shark relative selection values with the relative selection values derived for eight potential prey-species. We provide methodological considerations along with a framework and flexible approach to apply RSFs with machine learning algorithms to acoustic telemetry data and suggest marine ecologists and resource managers consider adopting such tools to help guide both conservation and management strategies.
Despite many positive benefits of ecotourism, increased human encounters with wildlife may have detrimental effects on wild animals. As charismatic megafauna, nesting and foraging sea turtles are ...increasingly the focus of ecotourism activities. The purpose of our study was to quantify the behavioral responses of immature green turtles (Chelonia mydas) to disturbance by snorkelers, and to investigate whether turtles have individual-level responses to snorkeler disturbance. Using a standardized disturbance stimulus in the field, we recorded turtle behaviors pre-and post-disturbance by snorkelers. Ninety percent of turtles disturbed by snorkeler (n = 192) initiated their flights at distances of ≤3 m. Using principal component analysis, we identified two distinct turtle personality types, ‘bold’and ‘timid’, based upon 145 encounters of 19 individually identified turtles and five disturbance response variables. There was significant intra-individual repeatability in behavioral responses to disturbance, but bolder turtles had more behavioral plasticity and less consistent responses than more timid individuals. Bolder individuals with reduced evasion responses might be at a higher risk of shark predation, while more timid turtles might have greater energetic consequences due to non-lethal predator effects and repeated snorkeler disturbance. Over the longer term, a turtle population with a mix of bold and timid individuals may promote more resilient populations. We recommend that snorkelers maintain > 3 m distance from immature green turtles when snorkeling, and that ecotourism activities be temporally and spatially stratified. Further, turtle watching guidelines need to be communicated to both tour operators and independent snorkelers to reduce the disturbance of turtles.
Objective
Shark depredation, the full or partial consumption of a hooked fish by a shark before it is landed, is an increasing source of human–wildlife conflict in recreational fisheries. Reports of ...shark depredation in the catch‐and‐release Tarpon (also known as Atlantic Tarpon) Megalops atlanticus fishery in the Florida Keys are increasing, specifically in Bahia Honda, a recreational fishing hot spot and a putative Tarpon prespawning aggregation site.
Methods
Using visual surveys of fishing in Bahia Honda, we quantified depredation rates and drivers of depredation. With acoustic telemetry, we simultaneously tracked 51 Tarpon and 14 Great Hammerheads (also known as Great Hammerhead Sharks) Sphyrna mokarran, the most common shark to depredate Tarpon, to quantify residency and spatial overlap in Bahia Honda.
Result
During the visual survey, 394 Tarpon were hooked. The combined observed shark depredation and immediate postrelease predation rate was 15.3% for Tarpon that were fought longer than 5 min. Survival analysis and decision trees showed that depredation risk was highest in the first 5–12 min of the fight and on the outgoing current. During the spawning season, Great Hammerheads shifted their space use in Bahia Honda to overlap with Tarpon core use areas. Great Hammerheads restricted their space use on the outgoing current when compared to the incoming current, which could drive increased shark–angler interactions.
Conclusion
Bahia Honda has clear ecological importance for both Tarpon and Great Hammerheads as a prespawning aggregation and feeding ground. The observed depredation mortality and postrelease predation mortality raise conservation concerns for the fishery. Efforts to educate anglers to improve best practices, including reducing fight times and ending a fight prematurely when sharks are present, will be essential to increase Tarpon survival and reduce shark–angler conflict.
Impact statement
Shark depredation in recreational fisheries is an increasing source of human–wildlife conflict in the United States. This study quantified shark depredation in the Tarpon fishery and characterized the spatial ecology of Great Hammerheads and Tarpon in Bahia Honda in the Florida Keys.
Background The effectiveness and benefits of regionalized trauma care are well substantiated; however, the effectiveness of regionalized burn care and potential benefits of burn center verification ...have not been fully validated. Study Design This was a retrospective study of all acute burn admissions using a statewide discharge database from October 1, 2000, to Septmber 30, 2007. Demographics, referral patterns, care practices, and outcomes were compared between 2 American Burn Association (ABA)–verified burn centers (VBCs) and the remaining 107 nonburn centers (NBCs) in North Carolina. Results Overall, 6,873 adult burn patients required admission, with 79% of them meeting ABA burn center referral criteria. Of the 5,402 patients meeting ABA referral criteria, 43% were admitted to an NBC, and 25% of all NBC patients had burn operations. Burns admitted to NBCs tended to involve the hand/wrist and lower extremities. Older patients with comorbidities/concomitant trauma were more likely to be admitted to NBCs (p < 0.0001); however, larger burns were more likely to be admitted to a VBC (p < 0.0001). More NBC patients were discharged to nursing homes (p < 0.0001). Patients with Medicare were more likely to be admitted to NBCs (p < 0.0001), and uninsured patients or those with Workman's Compensation insurance were more likely to be admitted to VBCs (p < 0.0001), and payer status remained a significant predictor of treatment at a VBC on regression analysis. Conclusions This is the most comprehensive study of its kind and demonstrates that ABA burn center referral criteria are not always used for effective regionalized burn care or to ensure the best possible outcomes. Even with establishment of the burn center verification process, the mere presence of a VBC is insufficient for effective regionalized care. A greater emphasis is needed on the development of burn care systems.
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