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1. Movement patterns of juvenile Atlantic tarpon (Megalops atlanticus) in Brewers Bay, St. Thomas, U.S. Virgin Islands

   https://doi.org/10.1186/s40317-021-00239-x  

   Duffing Romero, Mareike D. ; Matley, Jordan K. ; Luo, Jiangang ; Ault, Jerald S. ; Pittman, Simon J. ; Nemeth, Richard S. ( May 2021 , Animal Biotelemetry)

   Atlantic tarpon (Megalops atlanticus) are a highly migratory species ranging along continental and insular coastlines of the Atlantic Ocean. Due to their importance to regional recreational and sport fisheries, research has been focused on large-scale movement patterns of reproductively active adults in areas where they are of high economic value. As a consequence, geographically restricted focus on adults has left significant gaps in our understanding of tarpon biology and their movements, especially for juveniles in remote locations where they are common. Our study focused on small-scale patterns of movement and habitat use of juvenile tarpon using acoustic telemetry in a small bay in St. Thomas, US Virgin Islands.

   Four juvenile tarpon (80–95 cm FL) were tracked from September 2015 to February 2018, while an additional eight juveniles (61–94 cm FL) left the study area within 2 days after tagging and were not included in analysis. Four tarpon had > 78% residency and average activity space of 0.76 km²(range 0.08–1.17 km²) within Brewers Bay (1.8 km²). Their vertical distribution was < 18 m depth with occasional movements to deeper water. Activity was greater during day compared to night, with peaks during crepuscular periods. During the day tarpon used different parts of the bay with consistent overlap around the St. Thomas airport runway and at night tarpon typically remained in a small shallow lagoon. However, when temperatures in the lagoon exceeded 30 °C, tarpon moved to cooler, deeper waters outside the lagoon.

   Our results, although limited to only four individuals, provide new baseline data on the movement ecology of juvenile Atlantic tarpon. We showed that juvenile tarpon had high residency within a small bay and relatively stable non-overlapping daytime home ranges, except when seasonally abundant food sources were present. Fine-scale acoustic tracking showed the effects of environmental conditions (i.e., elevated seawater temperature) on tarpon movement and habitat use. These observations highlight the need for more extensive studies of juvenile tarpon across a broader range of their distribution, and compare the similarities and differences in behavior among various size classes of individuals from small juveniles to reproductively mature adults.

    

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2. Home range characteristics and diel patterns in space use of mutton snapper, Lutjanus analis, in St. Thomas, US Virgin Islands

   https://doi.org/10.1186/s40317-021-00237-z  

   Heidmann, Sarah L. ; Jossart, Jonathan ; Kimble, Melissa ; Nemeth, Richard S. ( December 2021 , Animal Biotelemetry)

   null (Ed.)

   Abstract Background The movement ecology of mutton snapper Lutjanus analis is poorly understood despite their ecological and economic importance in the Caribbean. Passive acoustic telemetry was used to determine home ranges of six adult L. analis , including diel patterns, in Brewers Bay, St. Thomas, US Virgin Islands. Understanding long-term space use, including site fidelity and habitat usage, is necessary to implement effective and appropriate management actions for a species with extensive space and resource needs. Results Individual L. analis were tracked over an average period of 316 days (range 125–509 days) and showed high site fidelity to relatively small home ranges (mean ± SD: 0.103 ± 0.028 km 2 , range 0.019–0.190 km 2 ) and core use areas with low overlap among individuals. Most home ranges had a habitat composition dominated by seagrass and to a lesser degree, coral reef and/or pavement. Nighttime activity spaces were distinct from but contained within daytime areas. Conclusions Mutton snapper showed strong site fidelity to home ranges in Brewers Bay. Two individuals that were absent from the array for more than a few hours were detected at separate arrays at spawning aggregation sites. This study expands upon knowledge of mutton snapper home range characteristics, highlights the importance of maintaining adjacent high-quality habitat types in any spatial management plan, and encourages the adoption of other types of management strategies, particularly for transient-aggregating species. 

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3. Genetic structure across urban and agricultural landscapes reveals evidence of resource specialization and philopatry in the Eastern carpenter bee, Xylocopa virginica L.

   https://doi.org/10.1111/eva.13078  

   Ballare, Kimberly M. ; Jha, Shalene ( August 2020 , Evolutionary Applications)

   Human activity continues to impact global ecosystems, often by altering the habitat suitability, persistence, and movement of native species. It is thus critical to examine the population genetic structure of key ecosystemservice providers across human‐altered landscapes to provide insight into the forces that limit wildlife persistence and movement across multiple spatial scales. While some studies have documented declines of bee pollinators as a result of human‐mediated habitat alteration, others suggest that some bee species may benefit from altered land use due to increased food or nesting resource availability; however, detailed population and dispersal studies have been lacking. We investigated the population genetic structure of the Eastern carpenter bee,Xylocopa virginica,across 14 sites spanning more than 450 km, including dense urban areas and intensive agricultural habitat.X. virginicais a large bee which constructs nests in natural and human‐associated wooden substrates, and is hypothesized to disperse broadly across urbanizing areas. Using 10 microsatellite loci, we detected significant genetic isolation by geographic distance and significant isolation by land use, where urban and cultivated landscapes were most conducive to gene flow. This is one of the first population genetic analyses to provide evidence of enhanced insect dispersal in human‐altered areas as compared to semi‐natural landscapes. We found moderate levels of regional‐scale population structure across the study system (Gʹ_ST = 0.146) and substantial co‐ancestry between the sampling regions, where co‐ancestry patterns align with major human transportation corridors, suggesting that human‐mediated movement may be influencing regional dispersal processes. Additionally, we found a signature of strong site‐level philopatry where our analyses revealed significant levels of high genetic relatedness at very fine scales (<1 km), surprising givenX. virginica'slarge body size. These results provide unique genetic evidence that insects can simultaneously exhibit substantial regional dispersal as well as high local nesting fidelity in landscapes dominated by human activity.

    

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4. Long-term monitoring provides insight into estuarine top predator (Carcharhinus leucas) resilience following an extreme weather event

   https://doi.org/10.3354/meps13269  

   Matich, P ; Strickland, BA ; Heithaus, MR ( April 2020 , Marine Ecology Progress Series)

   Chronic environmental change threatens biodiversity, but acute disturbance events present more rapid and immediate threats. In 2010, a cold snap across south Florida had wide-ranging impacts, including negative effects on recreational fisheries, agriculture, and ecological communities. Here, we use acoustic telemetry and historical longline monitoring to assess the long-term implications of this event on juvenile bull sharks Carcharhinus leucas in the Florida Everglades. Despite the loss of virtually all individuals (ca. 90%) within the Shark River Estuary during the cold snap, the catch per unit effort (CPUE) of age 0 sharks on longlines recovered through recruitment within 6-8 mo of the event. Acoustic telemetry revealed that habitat use patterns of age 0-2 sharks reached an equilibrium in 4-6 yr. In contrast, the CPUE and habitat use of age 3 sharks required 5-7 yr to resemble pre-cold snap patterns. Environmental conditions and predation risk returned to previous levels within 1 yr of the cold snap, but abundances of some prey species remained depressed for several years. Reduced prey availability may have altered the profitability of some microhabitats after the cold snap, leading to more rapid ontogenetic shifts to marine waters among sharks for several years. Accelerated ontogenetic shifts coupled with inter-individual behavioral variability of bull sharks likely led to a slower recovery rate than predicted based on overall shark CPUE. While intrinsic variation driven by stochasticity in dynamic ecosystems may increase the resistance of species to chronic and acute disturbance, it may also increase recovery time in filling the diversity of niches occupied prior to disturbance if resistive capacity is exceeded. 

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5. Habitat selection and 3D space use partitioning of resident juvenile hawksbill sea turtles in a small Caribbean bay

   https://doi.org/10.1007/s00227-021-03912-0  

   Matley, J. K. ; Johansen, L. K. ; Klinard, N. V. ; Eanes, S. T. ; Jobsis, P. D. ( August 2021 , Marine Biology)

   Abstract Understanding how aquatic animals select and partition resources provides relevant information about community dynamics that can be used to help manage conservation efforts. The critically endangered hawksbill sea turtle ( Eretmochelys imbricata ) spends an extended part of its juvenile development in coastal waters. A strong proclivity to remain resident in small areas, often in high density, raises questions about how juveniles partition resources including selection of habitat and spatial overlap among conspecifics. Using between 36 and 41 acoustic receivers in the 1.5 km 2 study site, this study quantified day-and-night habitat selection, as well as 2D and 3D space use of 23 juvenile hawksbills within two adjacent Caribbean foraging grounds—Brewers Bay and Hawksbill Cove, St. Thomas, US Virgin Islands—between 2015 and 2018. We found that coral reef, rock, and the artificial dolosse forming an airport runway, were the most strongly selected habitats based on resource selection indices. Individual activity spaces in 2D and 3D were both larger during the day compared to night, although the same parts of the bay were used by each individual during both periods. The 3D approach also showed deeper space use during the day. Weekly comparisons of activity space between individuals showed limited overlap (mean 95% UD overlap; day: 0.15 (2D) and 0.07 (3D), night: 0.11 (2D) and 0.03 (3D)), suggesting some degree of resource partitioning or territoriality. Results from this study provide relevant space use information for resource management of juvenile hawksbills, in which many populations are facing habitat degradation and population declines. 

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