Graduation Year

2023

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Marine Science

Major Professor

Frank Muller-Karger, Ph.D.

Committee Member

Pamela Hallock Muller, Ph.D.

Committee Member

David Naar, Ph.D.

Committee Member

Mark Luther, Ph.D.

Committee Member

Jorge Brenner, Ph.D.

Keywords

environmental change, Gavia immer, open-access databases, Phoebastria nigripes, Puffinus griseus, shorebirds

Abstract

Understanding the distribution of organisms is an important priority for society as we live through ecosystem transformations that threaten the well-being of all organisms. I have approached the dynamic and complex issue of studying biodiversity by using open-access seabird data collected along the Americas since the 1960s. I explained how these data have changed over time and space, how certain species populations could have shifted over time, and possible correlations between this potential geographic change and select environmental variables.

In Chapter 2 I evaluated the suitability of the open-access data archive Ocean Biodiversity Information System (OBIS) for supporting detailed inquiry into multi-decadal-scale geographic distributions of sea- and shorebird species in the Americas. The study included more than 680,000 occurrence records of 210 species collected between 1965 and 2018, evaluating them by marine ecoregion. I found that while OBIS contained a significant amount of data, the majority of records were from North American marine ecoregions, specifically from the Puget Trough/Georgia Basin and the Gulf of Maine/Bay of Fundy. Only a small portion of the data covered South America, the majority of which was collected in the Channels and Fjords of Southern Chile ecoregion. This study concluded that North American ecoregions could be used for future research, but that the community should share additional observations via OBIS to enable comprehensive, large-scale and detailed meta-analyses of spatial and temporal trends in marine and shorebird biodiversity.

In Chapter 3, I used OBIS occurrence (presence only) records from 1980–2018 for common loons (Gavia immer), sooty shearwaters (Puffinus griseus), and black-footed albatross (Phoebastria nigripes) to see how locations of these field-observations changed over time. The objective was to see how these changes illustrate the possibility of populations shifting northward or southward correlating with sea-surface temperatures, among other variables. These species were selected because of the larger volume of records available over the four-decade period compared to other seabird species. Records available for each of the four decades made these taxa useful for my study. Records for other taxa were too sparse to address changes over multi-decadal time scales. Results show that the average centroids of the distributions of sooty shearwater and black-footed albatross observations off the west coast of the United States of America (USA) moved northward by ~450 and 270 kilometers over 40 years, respectively. In contrast, the average centroids of the sooty shearwater and common loon observation distributions on the east coast of the USA moved southward by ~140 and 260 kilometers, respectively, over this period. However, these results have high uncertainty, and it is not possible to assign these changes to processes such as climate change at this time. Using the modelled Copernicus Global Ocean Physics Reanalysis (GLORYS12V1) environmental data product, I examined correlations between species’ geographic locations and abiotic factors (e.g., sea-surface temperatures, salinity, mixed-layer depth, northward and eastern current velocities, and sea-surface height).

The statistical analyses indicated that changes between decades in the average population distributions of common loons computed for any one season off the east coast of the USA were largely associated with sea-surface temperature changes in all seasons except spring. Locations of observations of sooty shearwaters on the east coast actually occurred such that records were matched to progressively cooler sea-surface temperature from decade to decade (~7℃ across 40 years), and leading to an apparent southward location of the spring centroids over time. For observations in autumn and summer, locations were associated with warmer waters (an increase of ~2.5℃ over 40 years, also corresponding to southward location of the bulk of shearwater observations). On the west coast, sooty shearwater observation distributions were positively associated with both temperature and salinity in spring, and negatively correlated in summer and autumn. Population observation distribution of black-footed albatross positively correlated with sea-surface temperature and salinity in spring, summer and autumn. Summer centroid temperatures for sooty shearwaters and black-footed albatross observations on the west coast increased by 1℃ and 0.5℃ over the 40-year period, respectively. In all cases except for common loons, records from winter seasons provided insufficient data for meaningful analyses. The results included numerous artifacts due to an uneven availability of records of species observations across years and from decade to decade.

Chapter 4 argues for the importance of integrating our communities, exploring scientific inquiry, and improving communication skills to bridge the gap between scientists and the public. This chapter presents four case studies from various parts of the Americas, including Brazil, Argentina, and Canada, which demonstrate diverse approaches such as technological applications, websites, community engagement activities, and events. The examples encompass a mobile “app” designed to reduce bycatch in shrimp fishing, participatory workshops utilizing graphic facilitation to raise awareness about environmental change, and an academic group that conducts accessible laboratory experiments to explain geophysical fluids. This chapter emphasizes the potential of these strategies to inform environmental management and everyday decision-making while fostering positive societal transformations. This can be easily applicable to, and was useful in, my seabird research. Clear and accessible communication between the scientific community and the public can raise awareness about the conservation needs of seabirds and promote community engagement.

Chapter 5 is a summary of the dissertation findings with recommendations for future work. Overall, my work highlights that even the most numerous seabird species records at present are insufficient to conduct robust temporal and spatial analyses and comprehensive assessments. The OBIS platform provides a foundation to understand sea- and shorebird distributions throughout North American marine ecoregions. However, to enable comprehensive analyses of spatial and temporal trends in marine and shorebird communities and their biodiversity, the temporal and geographic coverage of OBIS must be augmented with many more observations. Sharing observations via open-access databases such as OBIS can support monitoring and ecological analyses within and across marine ecoregions and contribute to future conservation efforts.

It is clear that there can be more coordinated efforts in capacity development and training in data management and use at the level of graduate study programs. Standardized, open databases are an essential component of creating, compiling and spreading knowledge. Using such information helps establish best practices for taxonomic and environmental observations, ultimately expanding and improving the availability of data on sea- and shorebirds. Furthermore, supporting scientific understanding and environmental interest in local communities can contribute to a more comprehensive and effective understanding of these species and their role in marine ecosystems.

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