Shannon Gowans

The common bottlenose dolphin (Tursiops truncatus) uses vocal learning and acoustic signals within their highly social, fission-fusion lifestyle. When communicating with other individuals, they often use individually distinctive vocalizations called “signature whistles” that function in conspecific recognition. The objective of this study was to identify signature whistles in a population of bottlenose dolphins in Tampa Bay and use photographic identification to link potential individuals with specific signature whistles. Acoustic recordings from 2009 to 2023 were manually analyzed using the SIGnature IDentification (SIGID) method. Thirty-three unique signature whistles were identified. Whistles were categorized based on their frequency contour, duration, and maximum frequency ranges. A minimally invasive method was used to align dolphin identifications with signature whistles. Using concurrent acoustic and dorsal fin photo-identification data, we potentially attributed signature whistles to two resident dolphins. In addition, group size was tested as a predictor variable for total signature whistle and unique signature whistle presence, which were both found to decrease as group size increased. This study helps us to understand the acoustic communication of this highly resident population of bottlenose dolphins, and it further highlights the importance of acoustic communication for this population in an increasingly urbanized and noisy environment.

Although killer whale (Orcinus orca) predation on humpback whales (Megaptera novaeangliae) is rarely witnessed, resultant scars on humpback flukes provide evidence of non-lethal interactions. Humpback whale photo-identification catalogs from the North Atlantic were used to evaluate humpback flukes (n = 10,957) for the presence and severity of killer whale scarification (e.g., rake marks, teeth indentations, missing tissue). Flukes were coded as none, light, moderate, or severe based on the extent of scarring. Even with increased sample sizes, especially for Norway and Iceland, the distribution of high-latitude humpbacks with killer whale scarring was consistent with prior studies: Atlantic Canada (21.7%), West Greenland (15.5%), Gulf of Maine (13.5%), Iceland (combined with East Greenland, 9.3%), and Norway (7.9%). For the first time, scarring rates are presented based on data from Ireland, Scotland, and England (11.0%) as well. Scarring frequencies generally differed between the eastern and western North Atlantic despite the co-occurrence of all migrating humpbacks in low-latitude breeding grounds, suggesting the occurrence of killer whale interactions in the distinct feeding grounds or along northward migration routes. While it was not possible to determine exactly where these interactions took place, the likelihood of a killer whale encounter and subsequent scar acquisition was greatest for humpbacks that feed in Atlantic Canada.

Microplastics have been recognized as an emerging contaminant. Copepods are abundant primary consumers in marine food webs. Interactions between copepods and microplastics can lead to negative health effects to the individual and may have implications for populations and ecosystems through biomagnification. Laboratory and field studies have observed various species of zooplankton ingesting microplastics, however, this is the first study to observe microplastic-copepod interactions in Tampa Bay. Over 2 years (November 2017-January 2020), 14 sampling cruises were conducted with seven stations throughout Tampa Bay. At each station copepods were collected by towing a 200 μm mesh ring net (0.5 m diameter) for 3 min. 1,000 individual Acartia tonsa copepods were picked from each sample and digested to release gut contents. Gut contents were stained in a Nile Red solution and then visualized using epifluorescent microscopy, quantified, photographed and sized using image analysis. In Tampa Bay, A. tonsa consumed fragments over fibers, ranging from 0.018 to 0.642 mm, with an average particle size of 0.076 mm. An overall average of 15.38 particles were ingested per 1,000 copepods, or 6.48 particles m–3 when normalized for environmental copepod concentrations. While significant differences were detected between stations and months, no clear spatial (from head to mouth of estuary) or temporal (between wet and dry seasons) trends in ingestion rate or ingested particle size were evident. These results show that A. tonsa ingested microplastics throughout Tampa Bay. These robust baseline data, for a copepod species that dominates estuarine zooplankton communities around the world, set the stage for valuable comparisons between estuaries with different physical mechanisms and levels of anthropogenic impact, allowing for exploration of how the environmental conditions impact ecological interactions.

Although there is growing concern about ingestion of microplastics by marine organisms, little research has been conducted on marine herbivores. This is the first study to document microplastic ingestion within the family Sirenia. Subsamples were collected from five locations in the gastrointestinal tracts (GI) of 26 dead manatees (Trichechus manatus latirostris) from Tampa Bay, Florida. During gross necropsies, macroplastic pieces were found in seven individuals (26.9%). Careful visual examination of the subsampled portions of the GI contents indicated that 19 individuals (73.1%) contained plastic particles. As five individuals had both macro and microplastic pieces, the overall frequency of occurrence of plastic ingestion was 76.9%. Due to the large volume of cellulose-rich ingested material, it was not feasible to analyze the entire gut contents, nor was it feasible to conduct chemical or enzymatic digestion; therefore, it is very likely that many microplastic pieces were not detected. Despite these technical challenges, it is clear that manatees in Tampa Bay are routinely consuming microplastics in addition to larger plastic pieces. Currently, nothing is known about the physiological effects of microplastic ingestion in sirenians, however environmental plastics could be concentrated by manatees through ingestion and the subsequent production of microplastics-laden feces.

Single-use plastics are a well-documented source of plastic debris and consequently a marine debris prevention policy priority. From August 2018 through May 2020, the Reduce Single-Use Project at Eckerd College (RSU) set out to raise the campus awareness of plastic marine debris, with the goal of reducing the community's single-use plastic consumption. To accomplish this, RSU facilitated a series of education and outreach events incentivizing vohmtary plastic reduction, including academic courses, community workshops, and coastal cleanups. Knowledge gains by the community were quantified through campus-wide surveys. Reduction of single-use plastic consumption was encouraged by providing reusable alternatives, inviting the community to participate in plastic reduction challenges, and ultimately working with the College administration to implement a campus-wide Break Free From Plastic Pledge barring the use of campus funds to purchase unnecessary single-use plastics. Behavioral changes were quantified via self-reported survey responses and observations of heavy plastic consumption areas on campus. Through this research, institutional policy changes that resulted in the direct removal of single-use plastics from campus locations (i.e., vendors offering wooden cutlery instead of plastic in the dining hall; swapping out plastic bags for paper at the campus bookstore) were i'ound to be the most effective method for reducing the consumption of single-use plastics. These policy changes were embraced by vendors and the College administration due to a demand for change from the campus community. Thus, individual behavior change fueled institutional policy change, which perpetuated further single-use plastic reduction.

Plastic consumption and disposal has detrimental effects on the natural environment and human health, yet demand for plastic continues to rise. College students remain an important, yet understudied, group that has the potential to drastically alter plastic consumption now and in the future. The present study is part of a larger project focusing on reducing single use plastic among college students and communities in two coastal locations - Eckerd College in St. Petersburg and the University of North Florida (UNF) in Jacksonville - using behavioral theory and a custom plastic reduction challenge app. The purpose of this pilot study is to test the behavioral survey and app that will be used in the larger study. A pilot sample of 47 UNF students (78.7 % women), ranging from 18-38 years old, vohmteered to participate in the pilot in exchange for extra credit in their courses. Participants used an app to record their use and refusals of plastic items during a week-long challenge to reduce plastic consumption. After the Plastic Challenge App, they completed an online survey assessing plastic use behavior and intentions, subjective norms (perceptions that others want them to reduce plastic), attitudes (evaluations of plastic use), and perceived behavioral control (beliefs that they can control their plastic use) based on the Theory of Planned Behavior (TPB). Participants reported the highest levels of refusal for plastic bags and highest levels of use for plastic bottles. Additionally, the plastic use reports from the app correlated strongly with the self-reported plastic use from the survey providing evidence of convergent validity for the app. The results of an exploratory regression indicated that the TPB model was significant in predicting plastic use intentions, F[3,43] = 4.14, p = .012. Though underpowered, this study provides initial evidence that subjective norms significantly affected participant's intentions toward single-use plastics. As expected, the TPB model predicted single use plastic behavior intentions and recordings of plastic use in the app related to responses to the survey. This lends support for the validity of the behavioral survey and fit for the behavioral model. Further analyses on larger samples will further test the effect of the app on TPB constructs and plastic use behavior by randomly assigning participants to use the app to track plastic consumption or to a control condition and comparing their survey results.

Single-use plastic has devastating impacts on the natural environment and scalable theory-based interventions are urgently needed to curb plastic consumption. The purpose of this study is to test the impact of two brief plastic reduction interventions on consumption on college campuses and whether these effects will be mediated by changes in the extended Theory of Planned Behavior (TPB) model consisting of attitudes, subjective norms, perceived behavioral control, moral norms, descriptive norms, and self-identity. 375 undergraduate students (77% female) from two colleges in the southeastern US completed baseline measures of plastic consumption beliefs and behavior in line with the extended TPB model. Participants were then randomized into one of three groups - control group (n = 152), app intervention group (who tracked plastic behavior on a mobile phone app for a week and received TPB-based daily messages via push notifications; n = 89), or pledge intervention group (who made a pledge to reduce plastic for a week and received TPB-based daily messages via email; n = 134). All participants completed the survey again after the intervention week. Results showed that the extended TPB model along with the intervention condition significantly predicted changes in plastic behavior over the week, (R2 = 0.24, p < .001). Additionally, mediation analysis revealed that the pledge group (compared to the control group) reported a significant decrease in plastic consumption over the week-long intervention, with indirect effects via changes in attitudes, perceived behavioral control, and descriptive norms. The app group (compared to the control group) decreased plastic consumption less and showed no change to the extended TPB constructs. Results suggest that plastic reduction interventions that influence the extended TPB constructs can be expected to have corresponding changes in plastic consumption behavior.

Tropical cyclones have large effects on marine ecosystems through direct (e.g., storm surge) and indirect (e.g., nutrient runoff) effects. Given their intensity, understanding their effects on the marine environment is an important goal for conservation and resource management. In June 2012, Tropical Storm Debby impacted coastal Florida including Tampa Bay. Acoustic recorders were deployed prior to the storm at a shallow water location inside Tampa Bay and a deeper water location in the Gulf of Mexico. Ambient noise levels were significantly higher during the storm, and the highest increases were observed at lower frequencies (<= 500 Hz). Although the storm did not directly hit the area, mean ambient noise levels were as high as 13.5 dB RMS above levels in non-storm conditions. At both the shallow water and the deep water station, the rate of fish calls showed a variety of patterns over the study period, with some rates decreasing during the storm and others showing no apparent reaction. The rates of fish calls were frequently correlated with storm conditions (storm surge, water temperature), but also with lunar cycle. Reactions to the storm were generally stronger in the inshore station, although fish sounds increased quickly after the storm's passage. Although this was not a major tropical cyclone nor a direct hit on the area, the storm did appear to elicit a behavioral response from the fish community, and ambient noise levels likely limited the abilities of marine species to use sound for activities such as communication. Given the increases in intensity and rainfall predicted for tropical cyclones due to climate change, further studies of the ecological effects of tropical cyclones are needed.

Human interaction (HI) is known to disturb cetaceans. Regional wildlife interaction guidelines exist to mitigate harmful impacts, but the efficacy of these guidelines is understudied. HI with bottlenose dolphins was documented opportunistically in Tampa Bay from 2009 to 2018. Vessel compliance to the guidelines was low with 80% of encounters being non-compliant. HI was observed in 33% of days in the field and in 22% of dolphin sightings. Poisson regression identified vessel type as a strong key factor related to compliance, with faster more maneuverable boats more likely to be non-compliant. Additionally, HI involved recreational vessels much more frequently than tourism vessels. These results likely underestimate true HI rates because of sampling limitations. Researchers should opportunistically document HI including vessel characteristics and vessel behavior to help quantify compliance. When developing HI guidelines and their promotion, managers should carefully consider which stakeholders engage in HI to best direct resources to that audience.

Tropical cyclones are severe weather systems which can potentially have a large effect on marine ecosystems through direct or indirect effects. In June 2012, Tropical Storm Debby formed in the Gulf of Mexico and had impacted coastal Florida including Tampa Bay. Acoustic recorders were deployed during the storm at a shallow inshore location inside Tampa Bay (Boca 2) and a location offshore in the Gulf of Mexico (Gulf 1). The soundscape before (17–21 June), during (22–26 June) and after (27 June–3 July) Tropical Storm Debby was investigated in two ways: third-octave spectral analysis of root-mean-square sound pressure levels and the identification and quantification of fish sounds in spectrograms. Single-factor ANOVAs indicated a significant increase in ambient noise analyzed in third-octave bands during the storm at both sites (p < 0.001), and an overall decrease in fish sound production during the storm at both sites (p < 0.001). Several species-specific sound production patterns were also found which correlated with the storm’s passage. The changes in ambient noise and biological vocalization was short-lived and returned back to normal within 48 h of the storm. This study is one of three studies to examine the effects of tropical cyclone on marine soundscapes, and the only study to identify sound production to the species level. Furthermore, the results from this study provide important information on the effects of tropical storms on marine communities and the fast rate of recovery after these storms.