Conserving and Restoring Critical Habitats

Coastal dune ecosystems face ongoing threats from human-mediated disturbance and alteration in resource availability. Because coastal dunes provide critical habitat for many organisms, like shorebirds, beach mice, and insects, any alteration in disturbance regimes and resource availability will likely cascade through plant communities to impact trophic webs. For instance, alteration in plant richness and productivity due to disturbance and resource availability will likely impact the abundance and diversity of insect herbivores, detritivores, and predators. To explore how disturbance and nutrient addition individually and simultaneously impact insect communities, we established twenty 5×5 m plots on Dauphin Island in which we crossed mechanical disturbance with a 10g per m2 addition of nitrogen, phosphorus, and potassium addition, which we established across five experimental blocks. To measure insect communities, we installed three pitfall traps in each plot that were collected weekly in the summers of 2022 and 2023, then identified to genus and enumerated. To understand whether insect communities are impacted directly by disturbance and nutrient addition or mediated through plant diversity and plant biomass, we will use structural equation modeling. Preliminary data supports that Orthoptera and Araneae abundance were reduced by disturbance and unaffected by nutrient addition. However, both Hymenoptera and Coleoptera were not impacted by either disturbance or nutrient addition treatments. Our results will help us better understand ecosystem impacts of disturbance and resource availability and recovery of ecosystem functioning following disturbance events.

Within the past century, anthropogenic impacts have become the strongest force altering ecosystems worldwide, and the strength of these disturbances are primarily connected to human population size and intensity of land-use. Coastal ecosystems are experiencing the highest rates of population growth and sea level rise to other coastal regions in the country. Coastal dunes are dynamic ecosystems that receive intense natural disturbances of sand accretion and erosion necessary to maintain ecosystem function; however, there has been an increase in anthropogenic disturbances such as urbanization, tourism, trampling, sea-level rise, and habitat destruction. Indicator species are often used to accurately identify ecosystem-level responses to ongoing disturbance. For instance, the Atlantic Ghost Crab (Ocypode quadrata) is a common indicator species on the Eastern Atlantic and Gulf of Mexico coasts because of its widespread distribution and sensitivity to natural and anthropogenic disturbances. We studied ghost crab density, burrow diameter, energy storage, reproductive success, stress hormone levels, and claw sizes to understand population dynamics in the face of human disturbance in 1) a mechanical disturbance x resource addition experiment established on Dauphin Island, AL, and 2) collecting ghost crab metrics across several beach locations along the Northern Gulf of Mexico. Based on our preliminary results on Dauphin Island, we found that there was little change in the burrow sizes across all treatment types, however, the average number of burrows were highest in the disturbed and disturbed + NPK plots, suggesting that the crabs preferred more open plots with less vegetation. These findings suggest that ghost crabs can potentially tolerate intermittently low-level physical disturbance and rebound quickly when in an ideal micro-habitat. 

Dune and marsh systems provide important ecological and economic benefits to the coastal communities they inhabit, such as mitigating storm impacts and providing aesthetic values. Along the US Gulf Coast, the need for dune and marsh restoration projects has become imperative as increased development, poor beach management, and other factors have led to the degradation of these critical habitats. The Plan-It Dunes & Marsh programs allows high school students the opportunity to gain an understanding and appreciation of native Mississippi ecosystems while participating in hands-on field work to restore these habitats across their own communities. To achieve these goals, a curriculum was created to pair with in-school educational training that develop skills in the installation of green infrastructure through propagation and planting of native dune and marsh plants. Classes had the opportunity to plant their plants at a restoration site as part of a project sponsored field trip. The development and implementation of this program has led to enhanced knowledge and stewardship of Mississippi's coastal environment.

Every year, millions of dollars are spent combating beach erosion. A critical component of any beach replenishment effort is the establishment of a dune plant community to help stabilize the new dunes, however, these efforts often experience high mortality, wasting time and money and setting projects back immensely. In other ecosystems, restoration success is boosted via the inoculation of soil microbes, like arbuscular mycorrhizal fungi (AMF). We predicted that integration of AMF and other soil microbes into dune restoration will improve plant survival and ability to withstand abiotic stressors which will aid beach replenishment efforts. To test this hypothesis, we grew several common Northern Gulf of Mexico dune plant species (Uniola paniculata, Ipomoea imperati, and Ipomoea pes-caprae) in beach sand collected from intact dunes on Dauphin Island, Alabama that was either sterilized, to remove soil microbial communities, or left as live soil. Next, we further split our live and sterile plants into low (0 pt), moderate (2.5 ppt), and high (5 ppt) salinity treatments to test if soil microbes improve resistance to abiotic stressors. We collected data on plant height, % senescence, and leaf number at two-week intervals. Overall, we found that the presence of soil microbial communities improved salinity tolerance in U. paniculata, reduced salinity tolerance in I. imperati and had no impact on I. pes-caprae. Together, our results suggest that benefits of soil microbial inoculants may be context dependent upon species or genotypes selected for coastal restoration outcomes and may shape the overall outcome of restoration succession.