Long-jawed orbweaving spiders (Tetragnatha sp.) as Sentinels of Mercury Contamination of the Trinity River

Authors: Tori Martinez, Macyn Willingham, Christopher Allender, Morgan Capone, Matt Chumchal, Ray Drenner, Cale Perry, Robby Peterson, Iris Schmeder, Andrew Todd, Tyler Williams

Human-made sources such as coal-fired power plants and artisanal gold mines have large outputs of emissions containing inorganic mercury (IHg), resulting in an overall increase in environmental mercury (Hg) levels across the globe. IHg is not bioavailable and therefore does not normally pose a risk to organisms. However, the conversion of IHg to bioavailable methylmercury (MeHg) that takes place in an aquatic ecosystem threatens human and wildlife health, given that MeHg is a neurotoxin. To investigate this further, the amount of MeHg must be determined for specific locations given that there is a large variation in inorganic mercury deposition throughout various landscapes and ecosystems. Specifically, this project examines the bioaccumulation of MeHg in aquatic food webs and individual bodies of water, through the use of shoreline spiders as a sentinel species. If excess mercury is present within an aquatic food web, there would be a presence of mercury in emergent aquatic insects. Shoreline spiders, then, prey on the emergent aquatic insects, resulting in an accumulation of mercury within their tissue. Shoreline spiders have been proposed as sentinels of MeHg but there have been relatively few studies examining biological factors that could influence the concentration of MeHg in their tissues. The objective of this study is to determine how spider size and sex can influence MeHg concentrations in the Clear and West Fork of the Trinity River. There is existing evidence that the two forks may have varying amounts of mercury accumulation, based on a study done in 2016. This study focused on the long-jawed orb weaver (Family Tetragnathidae; Tetragnatha sp.) shoreline spider, in which over 1000 were captured from June to August 2019. We preserved spiders in 95% ethanol followed by measurement of leg length (a proxy for body size), determination of spider sex and Hg analysis. In this presentation we will discuss the relationship between spider size, sex, and ecosystem contamination levels on Hg concentration.

Since the 19th century, Earth’s average surface temperature has risen 2 degrees Fahrenheit due to an increase in the pollution of greenhouse gases caused by human activity. The magnitude of food waste produced in the United States contributes to climate change through the methane released by the excess food discarded in landfills. Each year, 40 percent of food in the United States is never consumed due to food loss or waste along the supply chain including growers, consumers, retailers, and restaurants (NRDC 2020; SOFA 2019). However, millions of Americans are food insecure or live in areas known as food deserts that have little access to fresh food. Recent estimates suggest 690 million people around the world went hungry in 2019 (UNICEF 2020). For food systems to operate more sustainably, we must promote food recovery processes, one of which is composting. The purpose of this research is to first quantify the amount of food waste produced and then diverted from landfills through a community composting program in Fort Worth, Texas. Our group has partnered with Roy Pope Grocery to collect composting material and deliver it to the UNT Health Science Garden, where it is weighed, processed, composted, and later used in gardening plots. Through composting, we are able to limit the amount of greenhouse gases emitted in the air, in turn, fighting climate change and preventing its negative impacts on Earth’s ecosystem. We are analyzing four months of food waste via descriptive statistics and the EPA’s Waste Reduction Model (WARM).

Microbial interactions with plant biomass contribute significantly to the cycling of nutrients and contaminants in the environment. Primarily among these interactions is the role of fungal-induced degradation of organic matter, its regulatory effects on the carbon cycle, and pollutant transport. This study uses fungal colonization of spent coffee grounds as a model for understanding fungi-plant biomass interactions and their relationship to carbon stability and pollutant removal capacity. Results indicate that fungal-induced alterations of the plant material result in an increase in aromatic and a concomitant decrease in methyl components of the organic matter. This molecular alteration was accompanied by an increase in the carbon content of the remaining material, an increase in the carbon stability as determined by the materials R , and an increase in sorption capacity for cationic species as determined from gentian violet sorption to the materials. The results from this study could contribute additional knowledge to solving grand challenges in climate and pollution.

Excessive greenhouse gas emissions that result from unregulated energy exploitation contribute to climate change and air pollution. One way to restore the carbon balance within the earth’s systems is to increase carbon inputs by capturing atmospheric carbon and storing it in stable reservoirs, also known as Carbon Sequestration. Using the process of photosynthesis, plants absorb carbon dioxide from the atmosphere and convert it to organic carbon that is relatively more stable than gaseous carbon. The ability to sequester carbon varies across different vegetation species and the environments in which they grow. Using ArcGIS tools and free-access remote sensing data, this study will survey the spatial distribution of plant biomass and their effective carbon storage capacity in a case study located in Africa. The results from this study will i) identify facilities with the most effective carbon sequestration potential ii) help conservation programs in making landscaping decisions for future urban developments.

Bats provide many ecosystem services, including pest control, pollination, and seed dissemination, which are economically beneficial to humans. Yet as human populations continue to grow, leading to the increasing loss, degradation, and fragmentation of natural habitats to urban sprawl, wildlife species including bats are having to adapt to this unnatural environment. One important resource that bats must access in such environments is water. In natural landscapes, bats drink from ponds, lakes, streams, rivers, and even puddles, but in human-modified areas, studies have shown that bats can drink from drainage ditches, cattle troughs, and residential swimming pools. However, it is generally assumed that these resources are not preferred and, if present, more semi-natural water sources, such as retention and ornamental ponds, would be preferentially used. But what if we are incorrectly assuming that all semi-natural water sources are readily accessible and available to bats. To explore this uncertainty, we conducted behavioral observation surveys using thermal cameras and acoustic detectors to determine whether semi-natural water sources within Fort Worth, including the retention pond on the Texas Christian University (TCU) campus, were suitable for bats. Specifically, we compared bat drinking activity at these ponds and identified pond characteristics that might deter or encourage bats to drink at them. Our study revealed that the presence of artificial lights represented a major characteristic that deterred bats. In particular, we found that only when flood lights from the TCU soccer field were turned off, bat activity was recorded at the TCU retention pond. This result confirmed that not all water sources are readily accessible and available to bats, but turning lights off when they are not needed could effectively improve water availability for bats. It is findings such as these that can inform the enrichment of urban environments for bats and, therefore, aid their conservation.