The Fire and Tree Mortality Database, for Empirical Modeling of Individual Tree Mortality After Fire

Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across the globe. A major focus of past research has been on tree mortality from fire, as trees provide a vast range of biological services. We assembled a database of individual-tree records from prescribed fires and wildfires in the United States. The Fire and Tree Mortality (FTM) database includes records from 164,293 individual trees with records of fire injury (crown scorch, bole char, etc.), tree diameter, and either mortality or top-kill up to ten years post-fire. Data span 142 species and 62 genera, from 409 fires occurring from 1981-2016. Additional variables such as insect attack are included when available. The FTM database can be used to evaluate individual fire-caused mortality models for pre-fire planning and post-fire decision support, to develop improved models, and to explore general patterns of individual fire-induced tree death. The database can also be used to identify knowledge gaps that could be addressed in future research

Habitat utilization of Atlantic sturgeon Acipenser oxyrinchus oxyrinchus in the Delaware River, Bay and coastal Atlantic Ocean

Oliver, Matthew J.Animals utilize various environments throughout their life cycle to optimize growth, fitness, and survival. These environments are their habitats. As the lifecycle of an organism progresses, the resources needed, and thus the habitats preferred will change to fulfill the new requirements of the given life history stage. Resource needs for many organisms will also vary seasonally in both composition and specificity requiring organisms to shift their habitats to fulfill changing needs throughout the year. Incorporating species occurrence observations and environmental properties enables species distribution models to reliably estimate habitat locations. Destruction of habitat and overfishing beginning in the late 19th century severely depleted Atlantic Sturgeon populations. Subsequent to the boom and bust period of exploitation, there has been minimal fishing pressure and improving habitats. However, lack of recovery led to the 2012 listing of Atlantic Sturgeon under the Endangered Species Act. In this dissertation I utilize various sources of environmental data, species distribution modeling, and acoustic biotelemetry to gain insight into the occurrence and habitat use of adult Atlantic Sturgeon to further their protection and promote efficient resource management. ☐ To estimate adult Atlantic sturgeon spatial distributions during riverine occupancy in the Delaware River, I utilized a maximum entropy approach along with passive biotelemetry during the likely spawning season. I found that substrate composition and distance from the salt front significantly influenced the locations of adult Atlantic Sturgeon in the Delaware River. The movement of the salt front upstream as a result of dredging and climate change likely eliminated historic spawning habitats and currently threatens areas where Atlantic Sturgeon spawning may still be taking place. ☐ In the Delaware Bay I found that movement and residency patterns were driven primarily by depth, bottom temperature, and location. These findings revealed that as temperatures warm in the summer Atlantic Sturgeon maintain residency in deep areas near the mouth of the Delaware Bay where upwelling offshore waters keep bottom temperatures cooler than surrounding area. As water temperatures begin to cool in the fall this pattern of residency turns back into movement. ☐ By placing Atlantic Sturgeon in the context of dynamic, objective, and globally conservative seascapes, in a manner similar to landscape partitioning in the terrestrial environment, I was able to link Atlantic Sturgeon occurrence to one particular seascape associated with terrigenous input during their spring migration. To verify the seascape findings from the passive acoustic array I deployed an autonomous underwater vehicle to dynamically sample the seascape distribution in the coastal ocean to confirm the original hypothesis of selection for a given seascape. ☐ To expand the prediction of Atlantic Sturgeon occurrence for the entire seasonal cycle I matched fisheries independent biotelemetry observations of Atlantic Sturgeon with daily satellite observations to construct a time resolved spatial distribution model of Atlantic Sturgeon. I determined that depth, day-of-year, sea surface temperature, and light absorption by seawater are the most important predictors of Atlantic sturgeon occurrence. I found strong spatial differences in spring and fall migration patterns, when anthropogenic interactions peak. Cross-validated models correctly identified > 88% of biotelemetry observations in this study region and my models also correctly identified ~67% of fisheries dependent observations throughout the year. However, during their migrations, when harmful interactions were highest, models correctly identified ~91% of fisheries dependent observations. ☐ The Delaware Bay and River once supported the largest population of sturgeon in North America but due to anthropogenic impacts this population segment is severely depleted. Recent measures have aided to stabilize Atlantic Sturgeon populations but without further protection for habitats, such as those highlighted by this dissertation, recovery may never be realized. I strongly suggest that the dynamic models created in this body of work be used for guidance to managers and stakeholders to reduce interactions with this highly imperiled species thereby enhancing conservation and recovery efforts.University of Delaware, School of Marine Science and PolicyPh.D

Implantation and Recovery of Long-Term Archival Transceivers in a Migratory Shark with High Site Fidelity

Publisher's PDF.We developed a long-term tagging method that can be used to understand species assemblages and social groupings associated with large marine fishes such as the Sand Tiger shark Carcharias taurus.We deployed internally implanted archival VEMCO Mobile Transceivers (VMTs; VEMCO Ltd. Nova Scotia, Canada) in 20 adult Sand Tigers, of which two tags were successfully recovered (10%). The recovered VMTs recorded 29,646 and 44,210 detections of telemetered animals respectively. To our knowledge, this is the first study to demonstrate a method for long-term (~ 1 year) archival acoustic transceiver tag implantation, retention, and recovery in a highly migratory marine fish. Results show low presumed mortality (n = 1, 5%), high VMT retention, and that non-lethal recovery after almost a year at liberty can be achieved for archival acoustic transceivers. This method can be applied to study the social interactions and behavioral ecology of large marine fishes.University of Delaware. College of Earth, Ocean, and Environment

Density of observations by distance from salt front for telemetered adult Atlantic sturgeon in the Delaware River during the likely period of spawning from 2009-2012.

<p>Density of observations by distance from salt front for telemetered adult Atlantic sturgeon in the Delaware River during the likely period of spawning from 2009-2012.</p

Contemporary MaxEnt mean response curves of the covariates distance to the salt front (km), mixed reworking (mixed gravel, sand, and mud), nondepositional (cobble and bedrock), uniform reworking (mud), bedload (moderately well sorted sand and gravel), coarse grained reworking (poorly sorted sand and gravel), and fine deposition (mud and fluid mud).

<p>(0 = absence of covariate, 1 = presence of covariate). Mean is in red with ± one standard deviation in blue (two shades for the categorical substrate covariates). </p

Projected areas of adult Atlantic sturgeon occurrence for 4 different salt front location scenarios: a- contemporary location (rkm 103), b-historical location (rkm 92), c- location given climate change (rkm 114), d- location given drought conditions (rkm 164).

<p>Projected areas of adult Atlantic sturgeon occurrence for 4 different salt front location scenarios: a- contemporary location (rkm 103), b-historical location (rkm 92), c- location given climate change (rkm 114), d- location given drought conditions (rkm 164).</p

Shifting Distributions of Adult Atlantic Sturgeon Amidst Post-Industrialization and Future Impacts in the Delaware River: a Maximum Entropy Approach

<div><p>Atlantic sturgeon (<i>Acipenser oxyrinchus oxyrinchus</i>) experienced severe declines due to habitat destruction and overfishing beginning in the late 19^th century. Subsequent to the boom and bust period of exploitation, there has been minimal fishing pressure and improving habitats. However, lack of recovery led to the 2012 listing of Atlantic sturgeon under the Endangered Species Act. Although habitats may be improving, the availability of high quality spawning habitat, essential for the survival and development of eggs and larvae may still be a limiting factor in the recovery of Atlantic sturgeon. To estimate adult Atlantic sturgeon spatial distributions during riverine occupancy in the Delaware River, we utilized a maximum entropy (MaxEnt) approach along with passive biotelemetry during the likely spawning season. We found that substrate composition and distance from the salt front significantly influenced the locations of adult Atlantic sturgeon in the Delaware River. To broaden the scope of this study we projected our model onto four scenarios depicting varying locations of the salt front in the Delaware River: the contemporary location of the salt front during the likely spawning season, the location of the salt front during the historic fishery in the late 19^th century, an estimated shift in the salt front by the year 2100 due to climate change, and an extreme drought scenario, similar to that which occurred in the 1960’s. The movement of the salt front upstream as a result of dredging and climate change likely eliminated historic spawning habitats and currently threatens areas where Atlantic sturgeon spawning may be taking place. Identifying where suitable spawning substrate and water chemistry intersect with the likely occurrence of adult Atlantic sturgeon in the Delaware River highlights essential spawning habitats, enhancing recovery prospects for this imperiled species. </p> </div

Number of days adult Atlantic sturgeon were observed occupying each substrate type with expected number of days by each sediment type: FD- Fine Deposition, UR- Uniform Reworking, MR- Mixed Reworking, CR- Coarse Reworking, BL- Bedload, ND- Nondepositional.

<p>Number of days adult Atlantic sturgeon were observed occupying each substrate type with expected number of days by each sediment type: FD- Fine Deposition, UR- Uniform Reworking, MR- Mixed Reworking, CR- Coarse Reworking, BL- Bedload, ND- Nondepositional.</p

Acoustic receiver locations and 1 km detection radius overlain on the sediment composition map of the Delaware River (adapted from Sommerfield and Madson 2003), location of the salt front shown given four different scenarios, urban areas indicated through dark shading.

<p>Acoustic receiver locations and 1 km detection radius overlain on the sediment composition map of the Delaware River (adapted from Sommerfield and Madson 2003), location of the salt front shown given four different scenarios, urban areas indicated through dark shading.</p

Presence and absence of telemetered sharks.

<p>Detections of 20 adult Sand Tigers <i>Carcharias taurus</i> outfitted with VEMCO Mobile Transceivers (VMTs) on VEMCO VR-2W moored acoustic receivers located in the Delaware Bay, Delaware USA, the surrounding coastal ocean, and outside receiver arrays along the East Coast United States part of the Atlantic Cooperative Telemetry Network (ACT). All sharks were detected one or two years after surgery except Shark 1.</p