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Daniel Slone

Publications and source records attributed to Daniel Slone.

6 recordsLinked to original sources
USGS2024

Deep vs shallow: GPS tags reveal a dichotomy in movement patterns of loggerhead turtles foraging in a coastal bay

Background Individual variation in movement strategies of foraging loggerhead turtles have been documented on the scale of tens to hundreds of kilometers within single ocean basins. Use of different strategies among individuals may reflect variations in resources, predation pressure or competition. It is less common for individual turtles to use different foraging strategies on the scale of kilometers within a single coastal bay. We used GPS tags capable of back-filling fine-scale locations to document movement patterns of loggerhead turtles in a coastal bay in Northwest Florida, U.S.A. Methods Iridium-linked GPS tags were deployed on loggerhead turtles at a neritic foraging site in Northwest Florida. After filtering telemetry data, point locations were transformed to movement lines and then merged with the original point file to define travel paths and assess travel speed. Home ranges were determined using kernel density function. Diurnal behavioral shifts were examined by examining turtle movements compared to solar time. Results Of the 11 turtles tagged, three tracked turtles remained in deep (~ 6 m) water for almost the entire tracking period, while all other turtles undertook movements from deep water locations, located along edges and channels, to shallow (~ 1–2 m) shoals at regular intervals and primarily at night. Three individuals made short-term movements into the Gulf of Mexico when water temperatures dropped, and movement speeds in the Gulf were greater than those in the bay. Turtles exhibited a novel behavior we termed drifting. Conclusions This study highlighted the value provided to fine-scale movement studies for species such as sea turtles that surface infrequently by the ability of these GPS tags to store and re-upload data. Future use of these tags at other loggerhead foraging sites, and concurrent with diving and foraging data, would provide a powerful tool to better understand fine-scale movement patterns of sea turtles.

Florida↗
USGS2023

How do ambient conditions and management actions affect manatee movements and habitat use?

Kings Bay in northwest Florida, USA, is an important winter home of the largest aggregation of Florida manatee ( Trichechus manatus latirostris ), and the only location in the United States where visitors legally swim and interact with manatees. In addition to ambient conditions, visitors to the area and management actions have the potential to influence manatee behaviors. We tracked 32 manatees with satellite-linked global position system (GPS) telemetry tags in Kings Bay from 2006 to 2018. Also, personnel at Crystal River National Wildlife Refuge collected manatee counts at Three Sisters Springs from 2014 to 2017. Our objectives were to document the use of springs and other habitat components in Kings Bay relative to ambient water temperature, time of day, tide stage, and management actions within Three Sisters Springs and other manatee sanctuaries in the bay. Manatees that we tagged in Kings Bay spent a median 87% of the winter within the local study area, compared to 47% for animals that we tagged in the Florida Panhandle. Manatees showed preferences for King and Magnolia springs basins at low tide, indicating that they function as tidal refuges, when other locations may be less accessible; we also recorded within spring basin movements. Magnolia Spring Basin showed a significant diel pattern overall, and within basins, King Spring, Tarpon Hole, and Three Sisters Springs were used more during the night than during the day. All areas outside Kings Bay were used more at warmer ambient gulf water temperatures, while all of the springs basins were used more when gulf temperature was colder, especially Three Sisters Springs Basin. Management of Three Sisters Springs had an influence on manatee use during times of cold ambient gulf water temperatures; manatees used the springs more when the spring was closed to visitors, versus when the springs were completely open or when the spring lobes alone were closed. Manatee decisions were consistent with avoiding human interactions.

Florida↗
USGS2023

Quality of thermal refuges influences use by the cold-intolerant Florida manatee

ABSTRACT: Thermal refuges are habitats used by species for behavioral thermoregulation. These habitats can be highly dynamic and are often influenced by fluctuations in local climate. When protected species require thermal refuges, it is necessary to identify stable and high-quality areas by evaluating species use in response to variation in thermal refuge quality. Here, we assessed behavioral thermoregulation in the Florida manatee Trichechus manatus latirostris , a cold-intolerant marine mammal. Using metrics from ectotherm physiology, we evaluated thermal quality of 2 refuge types (passive thermal basins, natural springs) in 2 areas of their distribution. Thermal refuge quality was assessed with respect to the lower critical threshold of the manatee (20°C) and the surrounding ambient temperatures and compared between refuge types. We used GPS locations of manatees to quantify visits to refuges and calculated total visit duration in each refuge by individual manatees. At natural springs, we found a negative correlation between visit duration and ambient temperature during cold weather; visit duration also increased with the temperature differential between the spring and the lower critical thermal threshold. Visit duration at passive thermal basins was negatively correlated with the thermal differential between the refuge and the lower critical thermal threshold. The relationship between thermal refuge quality and time-use metrics sheds light on the potential implications of habitat degradation on animal energetics and behavior. Given these results, focusing on potential key refuges in each system may inform targeted management and habitat restoration efforts to maintain adequate thermal refuge environments for this listed species.

Florida↗
USGS2021

Analysis of body condition indices reveals different ecotypes of the Antillean manatee

Assessing the body condition of wild animals is necessary to monitor the health of the population and is critical to defining a framework for conservation actions. Body condition indices (BCIs) are a non-invasive and relatively simple means to assess the health of individual animals, useful for addressing a wide variety of ecological, behavioral, and management questions. The Antillean manatee ( Trichechus manatus manatus ) is an endangered subspecies of the West Indian manatee, facing a wide variety of threats from mostly human-related origins. Our objective was to define specific BCIs for the subspecies that, coupled with additional health, genetic and demographic information, can be valuable to guide management decisions. Biometric measurements of 380 wild Antillean manatees captured in seven different locations within their range of distribution were obtained. From this information, we developed three BCIs (BCI 1 = UG/SL, BCI 2 = W/SL 3 , BCI 3 = W/(SL*UG 2 )). Linear models and two-way ANCOVA tests showed significant differences of the BCIs among sexes and locations. Although our three BCIs are suitable for Antillean manatees, BCI 1 is more practical as it does not require information about weight, which can be a metric logistically difficult to collect under particular circumstances. BCI 1 was significantly different among environments, revealing that the phenotypic plasticity of the subspecies have originated at least two ecotypes—coastal marine and riverine—of Antillean manatees.

Puerto Rico↗
USGS2021

Invasion frustration: Can biotic resistance explain the small geographic range of non-native croaking gourami Trichopsis vittata (Cuvier, 1831) in Florida, USA?

Croaking gourami Trichopsis vittata is a non-native fish species that has maintained a reproducing population in Florida, USA, since at least the 1970s. However, unlike most other non-native fishes in Florida, T. vittata has not spread beyond its very small (ca. 5 km²) range. We suspected the inability of T. vittata to colonize new habitats may be due to biotic resistance by the native eastern mosquitofish Gambusia holbrooki. In laboratory experiments, we show that G. holbrooki causes physical damage to T. vittata and that T. vittata’s growth is reduced in the presence of G. holbrooki. While the effects of G. holbrooki on T. vittata were sub-lethal, they were severe enough to hamper its growth and could affect recruitment in the wild. These results support the hypothesis that small non-native fishes may be excluded from establishment or may only establish small ranges due to pressure from G. holbrooki. Biotic resistance may reduce invasion success and thus consideration of species interactions is useful for natural resource managers trying to evaluate the potential risk of new invaders.

Florida↗