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Deutsch, Charles J.; Bonde, Robert K.; Reid, James P.
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1998 |
Radio-tracking manatees from land and space: tag design, implementation, and lessons learned from long-term study.
Marine Technology Society Jour. 32(1): 18-29. 5 figs.
–Traces the development of the manatee radio-tag assembly, and describes how the technology has been implemented in the U.S. and Puerto Rico, including capture and tagging methods, strengths and weaknesses of the current tag design, relative merits of VHF and satellite-monitored PTT transmitters, contributions of radio-tagging to studies of manatee biology, and promising new developments in tag technology and analytical methods.
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Harvey, J. W.; Harr, Kendal E.; Murphy, D.; Walsh, Michael T.; Nolan, E. C.; Bonde, Robert K.; Pate, M. G.; Deutsch, Charles J.; Edwards, Holly H.; Clapp, W. L.
(detail)
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2009 |
Hematology of healthy Florida manatees (Trichechus manatus).
Veter. Clin. Pathol. 38(2): 183-193.
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Deutsch, Charles J.; Reynolds, John E., III
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2012 |
Florida manatee status and conservation issues: a primer. Chap. 3 in: E. M. Hines et al. (eds.), Sirenian conservation: issues and strategies in developing countries (q.v.).
Gainesville, University Press of Florida (xiv + 326): 23-35. 2 tabs., 1 map.
–Includes box essays by Michael G. Sorice (p. 29, "Transforming manatee tourism into ecotourism"), Jim Brown (p. 30, "Role of law enforcement in conservation of the Florida manatee"), and Kari A. Rood, Sheri L. Barton, & Cathy A. Beck (p. 32, "Partnering for success: Florida manatee photo-identification").
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Wong, Arthur W.; Bonde, Robert K.; Siegal-Willott, Jessica L.; Stamper, M. Andrew; Colee, James; Powell, James Arthur, Jr.; Reid, James P.; Deutsch, Charles J.; Harr, Kendal E.
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2012 |
Monitoring oral temperature, heart rate, and respiration rate of West Indian manatees (Trichechus manatus) during capture and handling in the field.
Aquatic Mammals 38(1): 1-16. 12 tabs. 5 figs. DOI: 10.1578/AM.38.1.2012.1
–ABSTRACT: West Indian manatees (Trichechus manatus) are captured, handled, and transported to facilitate conservation, research, and rehabilitation efforts. Monitoring manatee oral temperature (OT), heart rate (HR), and respiration rate (RR) during out-of-water handling can assist efforts to maintain animal well-being and improve medical response to evidence of declining health. To determine effects of capture on manatee vital signs, we monitored OT, HR, and RR continuously for a 50-min period in 38 healthy, awake, juvenile and adult Florida manatees (T. m. latirostris) and 48 similar Antillean manatees (T. m. manatus). We examined creatine kinase (CK), potassium (K+), serum amyloid A (SAA), and lactate values for each animal to assess possible systemic inflammation and muscular trauma. OT range was 29.5 to 36.2° C, HR range was 32 to 88 beats/min, and RR range was 0 to 17 breaths/5 min. Antillean manatees had higher initial OT, HR, and RR than Florida manatees (p < 0.001). As monitoring time progressed, mean differences between the subspecies were no longer significant. High RR over monitoring time was associated with high lactate concentration. Antillean manatees had higher overall lactate values ([mean ± SD] 20.6 ± 7.8 mmol/L) than Florida manatees (13.7 ± 6.7 mmol/L; p < 0.001). We recommend monitoring manatee OT, HR, and RR during capture and handling in the field or in a captive care setting.
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Martin, Julien; Sabatier, Quentin; Gowan, Timothy A.; Giraud, Christophe; Gurarie, Eliezer; Calleson, Charles Scott; Ortega-Ortiz, Joel G.; Deutsch, Charles J.; Rycyk, Athena M.; Koslovsky, Stacie M.
(detail)
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2015 |
A quantitative framework for investigating risk of deadly collisions between marine wildlife and boats.
Methods in Ecology and Evolution 7: 42-50. 3 figs. DOI: 10.1111/2041-210X.12447. Published online Nov. 12, 2015.
–ABSTRACT: 1. Speed regulations of watercraft in protected areas are designed to reduce lethal collisions with wildlife but can have economic consequences. We present a quantitative framework for investigating the risk of deadly collisions between boats and wildlife.
2. We apply encounter rate theory to demonstrate how marine mammal–boat encounter rate can be used to predict the expected number of deaths associated with management scenarios. We illustrate our approach with management scenarios for two endangered species: the Florida manatee Trichechus manatus latirostris and the North Atlantic right whale Eubalaena glacialis. We used a Monte Carlo simulation approach to demonstrate the uncertainty that is associated with our estimate of relative mortality.
3. We show that encounter rate increased with vessel speed but that the expected number of encounters varies depending on the boating activities considered. For instance, in a scenario involving manatees and boating activities such as water skiing, the expected number of encounters in a given area (in a fixed time interval) increased with vessel speed. In another scenario in which a vessel made a transit of fixed length, the expected number of encounters decreases slightly with boat speed. In both cases, the expected number of encounters increased with distanced travelled by the boat. For whales, we found a slight reduction (˜0·1%) in the number of encounters under a scenario where speed is unregulated; this reduction, however, is negligible, and overall expected relative mortality was ˜30% lower under the scenario with speed regulation. The probability of avoidance by the animal or vessel was set to 0 because of lack of data, but we explored the importance of this parameter on the model predictions. In fact, expected relative mortality under speed regulations decreases even further when the probability of avoidance is a decreasing function of vessel speed.
4. By applying encounter rate theory to the case of boat collisions with marine mammals, we gained new insights about encounter processes between wildlife and watercraft. Our work emphasizes the importance of considering uncertainty when estimating wildlife mortality. Finally, our findings are relevant to other systems and ecological processes involving the encounter between moving agents.
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Edwards, Holly H.; Martin, Julien; Deutsch, Charles J.; Muller, R. G.; Koslovsky, Stacie M.; Smith, A. J.; Barlas, M. E.
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2016 |
Influence of manatees' diving on their risk of collision with watercraft.
PLOS One 11(4): e0151450. https://doi.org/10.1371/journal.pone.0151450. 2 tabs. 5 figs. Apr. 6, 2016.
–ABSTRACT: Watercraft pose a threat to endangered Florida manatees (Trichechus manatus latirostris). Mortality from watercraft collisions has adversely impacted the manatee population's growth rate, therefore reducing this threat is an important management goal. To assess factors that contribute to the risk of watercraft strikes to manatees, we studied the diving behavior of nine manatees carrying GPS tags and time–depth recorders in Tampa Bay, Florida, during winters 2002–2006. We applied a Bayesian formulation of generalized linear mixed models to depth data to model the probability (Pt) that manatees would be no deeper than 1.25 m from the water's surface as a function of behavioral and habitat covariates. Manatees above this threshold were considered to be within striking depth of a watercraft. Seventy-eight percent of depth records (individual range 62–86%) were within striking depth (mean = 1.09 m, max = 16.20 m), illustrating how vulnerable manatees are to strikes. In some circumstances manatees made consecutive dives to the bottom while traveling, even in areas >14 m, possibly to conserve energy. This is the first documentation of potential cost-efficient diving behavior in manatees. Manatees were at higher risk of being within striking depth in shallow water (<0.91 m), over seagrass, at night, and while stationary or moving slowly; they were less likely to be within striking depth when ?50 m from a charted waterway. In shallow water the probability of a manatee being within striking depth was 0.96 (CI = 0.93–0.98) and decreased as water depth increased. The probability was greater over seagrass (Pt = 0.96, CI = 0.93–0.98) than over other substrates (Pt = 0.73, CI = 0.58–0.84). Quantitative approaches to assessing risk can improve the effectiveness of manatee conservation measures by helping identify areas for protection.
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Harshaw, Lauren T.; Larkin, Iskande V.; Bonde, Robert K.; Deutsch, Charles J.; Hill, Richard C.
(detail)
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2016 |
Morphometric body condition indices of wild Florida manatees (Trichechus manatus latirostris).
Aquat. Mamms. 42(4): 428-439. doi:10.1578/AM.42.4.2016.428. Nov. 18, 2016.
–ABSTRACT: In many species, body weight (W) increases geometrically with body length (L), so W/L3 provides a body condition index (BCI) that can be used to evaluate nutritional status once a normal range has been established. No such index has been established for Florida manatees (Trichechus manatus latirostris). This study was designed to determine a normal range of BCIs of Florida manatees by comparing W in kg with straight total length (SL), curvilinear total length (CL), and umbilical girth (UG) in m for 146 wild manatees measured during winter health assessments at three Florida locations. Small calves to large adults of SL from 1.47 to 3.23 m and W from 77 to 751 kg were compared. BCIs were significantly greater in adult females than in adult males (p < 0.05). W scaled proportionally to L3 in females but not in males, which were slimmer than females. The logarithms of W and of each linear measurement were regressed to develop amended indices that allow for sex differences. The regression slope for log W against log SL was 2.915 in females and 2.578 in males; W/SL2.915 ranged from 18.9 to 29.6 (mean 23.2) in females, and W/SL2.578 ranged from 24.6 to 37.3 (mean 29.8) in males. Some BCIs were slightly (4%), but significantly (p <- 0.05), higher for females in Crystal River than in Tampa Bay or Indian River, but there was no evidence of geographic variation in condition among males. These normal ranges should help evaluate the nutritional status of both wild and rehabilitating captive manatees.
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Runge, Michael C.; Sanders-Reed, Carol A.; Langtimm, Catherine A.; Hostetler, J. A.; Martin, Julien; Deutsch, Charles J.; Ward-Geiger, Leslie I.; Mahon, Gary L.
(detail)
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2017 |
Status and threats analysis for the Florida manatee (Trichechus manatus latirostris), 2016.
U.S. Geological Survey Scientific Investigations Report 2017-5030: ix + 40. 8 tabs. 18 figs. https://doi.org/10.3133/sir20175030
–ABSTRACT: Trichechus manatus (West Indian manatee), especially T. m. latirostris, the Florida subspecies, has been the focus of conservation efforts and extensive research since its listing under the Endangered Species Act of 1973. To determine the status of, and severity of threats to, the Florida manatee, a comprehensive revision and update of the manatee Core Biological Model was completed and used to perform a population viability analysis for the Florida manatee. The probability of the Florida manatee population falling below 500 adults on either the Gulf or East coast within the next 100 years was estimated to be 0.42 percent. This risk of quasi-extinction is low because the estimated adult survival rates are high, the current population size is greater than 2,500 on each coast, and the estimated carrying capacity for manatees is much larger than the current abundance estimates in all four regions of Florida. Three threats contribute in roughly equal measures to the risk of quasi-extinction: watercraft-related mortality, red-tide mortality, and loss of warm-water habitat. Only an increase in watercraft-related mortality has the potential to substantially increase the risk of quasi-extinction at the statewide or coastal level. Expected losses of warm-water habitat are likely to cause a major change in the distribution of the population from the regions where manatees rely heavily on power plant effluents for warmth in winter (Southwest and Atlantic regions) to the regions where manatees primarily use natural springs in winter (Northwest and Upper St. Johns regions). The chances are nearly 50 percent that manatee populations in the Southwest and Atlantic regions will decrease from their 2011 levels by at least 30 percent over the next century.
A large number of scenarios were examined to explore the possible effects of potential emerging threats, and in most of them, the risk of quasi-extinction at the coastal scale within 100 years did not rise above 1 percent. The four exceptions are scenarios in which the rate of watercraft-related mortality increases, carrying capacity is only a fraction of the current estimates, a new chronic source of mortality emerges, or multiple threats emerge in concert. Even in these scenarios, however, the risk of falling below 500 adults on either the East coast or the Gulf coast within 100 years from 2011 is less than 10 percent. High adult survival provides the population with strong resilience to a variety of current and future threats. On the basis of these analyses, we conclude that if these threats continue to be managed effectively, manatees are likely to persist on both coasts of Florida and remain an integral part of the coastal Florida ecosystem through the 21st century. If vigilance in management is reduced, however, the scenarios in which manatees could face risk of decline become more likely.
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Harvey, J. W.; Harr, Kendal E.; Murphy, D.; Walsh, Michael T.; de Wit, Martine; Deutsch, Charles J.; Bonde, Robert K.
(detail)
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2018 |
Serum proteins in healthy and diseased Florida manatees (Trichechus manatus latirostris).
Comparative Clinical Pathology 27(6): 1707-1716. doi: 10.1007/s00580-018-2797-z. Nov. 2018; Publ. online Aug. 3, 2018.
–ABSTRACT: A major goal of this study was to determine whether serum protein fractions of healthy Florida manatees differ with age, sex, or living environments (wild versus housed). A second goal was to determine which serum protein fractions vary in diseased versus healthy manatees. Serum protein fractions were determined using agarose gel electrophoresis. Healthy adults had slightly higher total serum protein and total globulin concentrations than younger animals. This largely resulted from an increase in gamma globulins with age. Total serum protein, albumin, alpha-1 globulin, beta globulin, and total globulin concentrations were slightly higher in housed manatees compared to wild manatees, but there was no significant difference in the albumin/globulin (A/G) ratio, suggesting a difference in hydration between these groups. No significant differences were attributable to sex or pregnancy. Serum albumin concentrations and A/G ratios were significantly lower for manatees with boat trauma, entanglements, emaciation, or cold stress compared to healthy manatees. Variable increases were seen in alpha-1 globulins, alpha-2 globulins, beta globulins, and gamma globulins. These globulin fractions contain positive acute-phase proteins and immunoglobulins, and their increases may reflect acute or chronic active inflammation. Changes in serum protein fractions were not consistent enough to justify the use of serum protein electrophoresis as a routine diagnostic test for manatees. However, serum (or plasma) protein electrophoresis is required when accurate values for albumin and globulins are needed in manatees and in determining which protein fractions may account for a hyperproteinemia or hypoproteinemia reported in a clinical chemistry panel.
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Rycyk, Athena M.; Deutsch, Charles J.; Barlas, Margaret E.; Hardy, Stacie K.; Frisch, Katherine; Leone, Erin H.; Nowacek, Douglas P.
(detail)
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2018 |
Manatee behavioral response to boats.
Mar. Mamm. Sci. 34(4): 924-962. 5 tabs. 15 figs. + suppl. information. doi:10.1111/mms.12491. Feb. 28, 2018.
–ABSTRACT: The long?term viability of the Florida manatee is threatened in part by mortality from boat collisions. This study investigated manatee behavior during boat approaches to better understand factors that lead to manatee–boat collisions. Digital acoustic recording tags (DTAGs) and Argos?linked GPS tags were deployed on 18 manatees in southwest Florida, and boat traffic around them was mapped. Suites of manatee behavioral, environmental, and boat?related factors were recorded during opportunistic boat passes. We built generalized linear mixed models to determine which factors accounted for variation in occurrence, number, and timing of manatee behavioral changes during boat passes. Manatees responded to boats, changing their orientation, depth, and fluking behavior most often when a boat approached closely (<10 m). Manatees were also more likely to change their depth when not on a seagrass bed and when actively fluking before a boat pass. Boat speed did not affect the occurrence or intensity of manatee response. Compared to fast approaches, however, slower passes allowed the manatee more time to respond, and behavioral change occurred earlier relative to the time of the boat's closest point of approach. We conclude that faster boats likely pose a greater risk of collision with manatees than do slower boats.
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Hardy, Stacie K.; Deutsch, Charles J.; Cross, Tiffanie A.; de Wit, Martine; Hostetler, Jeffrey A.
(detail)
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2019 |
Cold-related Florida manatee mortality in relation to air and water temperatures.
PLoS ONE 14(11): e0225048. 4 tabs. 8 figs. + online supporting information. doi.org/10.1371/journal.pone.0225048 Nov. 21, 2019.
–ABSTRACT: Many tropical and subtropical species are sensitive to sudden temperature changes, especially drops in temperature. During winters 2009–2010 and 2010–2011, unusually cold temperatures occurred in many parts of Florida, USA, resulting in increased mortality of Florida manatees, sea turtles, fish, corals, and other species. The Florida manatee, in particular, is highly susceptible to cold stress and death when water temperatures drop below 20°C. We sought to characterize the magnitude and timing of reports of cold-related manatee carcasses in relation to fluctuations in water and air temperatures in central-east and central-west Florida during the six winters from 2008 to 2014. We used a generalized linear model to predict counts of manatee carcasses with a cold-related cause of death reported over 7-day bins in relation to various short-term (two weeks or less) and cumulative (incrementally summed from the start of the winter) heating-degree-day effects (HDD; < 20°C) and a categorical winter variable. Using water temperature data, the top-ranked model in both regions included a short-term temperature effect (14-day HDD sum) that preceded increases in reports of cold-related manatee carcasses by 7 days. Cumulative exposure to cold weather over the winter amplified effects on mortality in the central-east region. Quantifying the relationship between cold events and manatee mortality helps us prepare for rescue and salvage operations when extremely cold weather is forecast. This is especially important because anticipated loss or degradation of warm-water refuges due to human activities and sea level rise could potentially impact the manatee population in the future. These methods could also be applied to other species susceptible to cold-related mortality.
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Harvey, J. W.; Harr, Kendal E.; Murphy, D.; Walsh, Michael T.; de Wit, Martine; Deutsch, Charles J.; Bonde, Robert K.
(detail)
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2019 |
Serum iron analytes in healthy and diseased Florida manatees (Trichechus manatus latirostris).
Jour. Comparative Pathology 173: 58-70. 8 figs. 4 tabs. doi:10.1016/j.jcpa.2019.10.006. Publ. online Nov. 14, 2019.
–ABSTRACT: Serum iron concentration is usually decreased in true iron deficiency and with inflammatory disease in man and domestic animals. Serum total iron binding capacity (TIBC) may be increased in true iron deficiency and decreased with inflammatory disease. This prospective study was designed to measure serum iron analytes in healthy free-ranging and housed Florida manatees (Trichechus manatus latirostris) of both sexes and various ages and to evaluate the effects of diseases common to manatees on these analytes. Blood samples were collected without anticoagulant from 137 healthy free-ranging manatees, 90 healthy housed manatees and 74 free-ranging diseased manatees, and serum was prepared by centrifugation. Serum iron concentration and unsaturated iron binding capacity were measured colourimetrically, and TIBC and percent transferrin saturation with iron were calculated. Serum amyloid A (SAA) was measured to assist in the health assessment of manatees and provide evidence of inflammation in diseased manatees. Based on the serum iron analytes, iron availability was lower in immature manatees compared with adults, and it was lower in housed manatees compared with free-ranging manatees. In contrast to other mammals studied, serum iron concentration was elevated rather than depressed in late pregnancy. Serum iron concentrations and transferrin saturation with iron percentages were significantly lower, and SAA concentrations were significantly higher, in diseased (ill and injured) manatees compared with healthy manatees. Serum iron concentration and transferrin saturation with iron values were negatively correlated with SAA concentrations, and manatees with the highest SAA concentrations had lower serum TIBC values. These findings indicate that inflammation is the major factor responsible for alterations in iron analytes in diseased manatees. Consequently, hypoferraemia may be used as supportive evidence of inflammatory disease in manatees (unless haemorrhage is also present). A decision threshold of ?13.8 ?mol/l was determined for hypoferraemia using receiver operating curve analysis. Based on studies in man and domestic animals, iron therapy is unnecessary for manatees with hypoferraemia associated with inflammation and has the potential for causing tissue damage and increased susceptibility to bacterial infections.
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Lonati, Gina L.; Howell, Amber R,; Hostetler, Jeffrey A.; Schueller, Paul; de Wit, Martine; Bassett, Brandon L.; Deutsch, Charles J.; Ward-Geiger, Leslie I.
(detail)
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2019 |
Accuracy, precision, and error in age estimation of Florida manatees using growth layer groups in earbones.
Jour. Mammalogy 100(4):1350-1363. 5 tabs. 7 figs. + online supplementary files. https://doi.org/10.1093/jmammal/gyz079 July 27, 2019 (publ. online May 30, 2019).
–ABSTRACT: Ages of Florida manatees (Trichechus manatus latirostris) can be estimated by counting annual growth layer groups (GLGs) in the periotic dome portion of the tympanoperiotic complex of their earbones. The Florida Fish and Wildlife Conservation Commission manages an archive of more than 8,700 Florida manatee earbones collected from salvaged carcasses from 1989 to 2017. Our goal was to comprehensively evaluate techniques used to estimate age, given this large sample size and changes to processing protocols and earbone readers over time. We developed new standards for estimating ages from earbones, involving two independent readers to obtain measurements of within- and between-reader precision. To quantify accuracy, precision, and error, 111 earbones from manatees with approximately known ages (first known as calves: "KAC") and 69 earbones from manatees with minimum known ages ("MKA," based on photo-identification sighting histories) were processed, and their ages were estimated. There was greater precision within readers (coefficient of variation, CV: 2.4–8.5%) than between readers (CV: 13.1–13.3%). The median of age estimates fell within the true age range for 63.1% of KAC cases and was at least the sighting duration for 75.0% of MKA cases. Age estimates were generally unbiased, as indicated by an average raw error ± SD of ?0.05 ± 3.05 years for the KAC group. The absolute error (i.e., absolute value of raw error) of the KAC data set averaged 1.75 ± 2.50 years. Accuracy decreased and error increased with increasing known age, especially for animals over 15 years old, whose ages were mostly underestimated due to increasing levels of resorption (the process of bone turnover that obscures GLGs). Understanding the degree of uncertainty in age estimates will help us assess the utility of age data in manatee population models. We emphasize the importance of standardizing and routinely reviewing age estimation and processing protocols to ensure that age data remain consistent and reliable.
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Udell, Bradley J.; Martin, Julien; Fletcher, Robert J., Jr.; Bonneau, Mathieu; Edwards, Holly H.; Gowan, Timothy A.; Hardy, Stacie K.; Gurarie, Eliezer; Calleson, Charles S.; Deutsch, Charles J.
(detail)
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2019 |
Integrating encounter theory with decision analysis to evaluate collision risk and determine optimal protection zones for wildlife.
Jour. Applied Ecology 56(5): 1050-1062. https://doi.org/10.1111/1365-2664.13290 May 2019.
–ABSTRACT: Better understanding human–wildlife interactions and their links with management can help improve the design of wildlife protection zones. One example is the problem of wildlife collisions with vehicles or human-built structures (e.g., power lines, wind farms). In fact, collisions between marine wildlife and watercraft are among the major threats faced by several endangered species of marine mammals. Natural resource managers are therefore interested in finding cost-effective solutions to mitigate these threats.
We combined abundance estimators with encounter rate theory to estimate relative lethal collision risk of the Florida manatee (Trichechus manatus latirostris) from watercraft. We first modelled seasonal abundance of watercraft and manatees using a Bayesian analysis of aerial survey count data. We then modelled relative lethal collision risk in space and across seasons. Finally, we applied decision analysis and Linear Integer Programming to determine the optimal design of speed zones in terms of relative risk to manatees and costs to waterway users. We used a Pareto efficient frontier approach to evaluate the performance of alternative zones, which included additional practical considerations (e.g., spatial aggregation of speed zones) in relation to the optimal zone configurations.
Under the various relationships for probability of death given strike speed that we considered, the current speed zones reduced the relative lethal collision risk by an average of 51.5% to 70.0% compared to the scenario in which all speed regulations were removed (i.e., the no-protection scenario). We identified optimal zones and near-optimal zones with additional management considerations that improved upon the current zones in terms of cost or relative risk.
Policy implications. Our analytical framework combines encounter rate theory and decision analysis to quantify the effectiveness of speed zones in protecting manatees while accounting for uncertainty. Our approach can be used to optimize the design of protection zones intended to reduce conflicts between human waterborne activity and marine mammals. This framework could be extended to address many other problems of human–wildlife interactions, such as the optimal placement of wind farms to minimize collisions with wildlife or the optimal allocation of ranger effort to mitigate poaching threats.
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Harvey, J. W.; Harr, K. E.; Murphy, D.; Walsh, M. T.; de Wit, Martine; Deutsch, Charles J.; Bonde, Robert K.
(detail)
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2020 |
Serum iron analytes in healthy and diseased Florida manatees (Trichechus manatus latirostris).
Jour. Comparative Pathology 173: 58-70. 4 tabs. 8 figs. https://doi.org/10.1016/j.jcpa.2019.10.006 Publ. online Nov. 2019.
–ABSTRACT: Serum iron concentration is usually decreased in true iron deficiency and with inflammatory disease in man and domestic animals. Serum total iron binding capacity (TIBC) may be increased in true iron deficiency and decreased with inflammatory disease. This prospective study was designed to measure serum iron analytes in healthy free-ranging and housed Florida manatees (Trichechus manatus latirostris) of both sexes and various ages and to evaluate the effects of diseases common to manatees on these analytes. Blood samples were collected without anticoagulant from 137 healthy free-ranging manatees, 90 healthy housed manatees and 74 free-ranging diseased manatees, and serum was prepared by centrifugation. Serum iron concentration and unsaturated iron binding capacity were measured colourimetrically, and TIBC and percent transferrin saturation with iron were calculated. Serum amyloid A (SAA) was measured to assist in the health assessment of manatees and provide evidence of inflammation in diseased manatees. Based on the serum iron analytes, iron availability was lower in immature manatees compared with adults, and it was lower in housed manatees compared with free-ranging manatees. In contrast to other mammals studied, serum iron concentration was elevated rather than depressed in late pregnancy. Serum iron concentrations and transferrin saturation with iron percentages were significantly lower, and SAA concentrations were significantly higher, in diseased (ill and injured) manatees compared with healthy manatees. Serum iron concentration and transferrin saturation with iron values were negatively correlated with SAA concentrations, and manatees with the highest SAA concentrations had lower serum TIBC values. These findings indicate that inflammation is the major factor responsible for alterations in iron analytes in diseased manatees. Consequently, hypoferraemia may be used as supportive evidence of inflammatory disease in manatees (unless haemorrhage is also present). A decision threshold of ?13.8 ?mol/l was determined for hypoferraemia using receiver operating curve analysis. Based on studies in man and domestic animals, iron therapy is unnecessary for manatees with hypoferraemia associated with inflammation and has the potential for causing tissue damage and increased susceptibility to bacterial infections.
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Bibliography and Index of the Sirenia and Desmostylia 