Date of Award
2025
Degree Type
Dissertation
Degree Name
Doctor of Philosophy in Biological and Environmental Sciences
Department
Natural Resources Science
First Advisor
Carol S. Thornber
Second Advisor
Marta Gomez-Chiarri
Abstract
Climate change and anthropogenic stressors in marine costal habitats include increased sea surface temperatures (SST) and precipitation. The impacts of these stressors can affect ecosystem engineer species, which create three-dimensional habitat space in and provide various ecosystem services that modify and maintain ecosystem resources. In Narragansett Bay, RI, USA there is anecdotal evidence that the habitat forming species of kelp, Saccharina latissima, and rockweeds, Ascophyllum nodosum and Fucus spp, are changing but few long-term studies have been conducted to verify this. We compared the historical studies from the 1960s to 2010s on seaweeds in Narraganset Bay to modern SCUBA surveys at the same sites to quantify the changes happening in density, via percent cover, and distribution for these species via presence. Kelp percent cover and presence decreased at all sites, with larger losses in the most southern sites in the Bay from warming sea surface temperatures (SST). Rockweed percent decreased at some sites and increased at others, with Fucus spp. contributing to the increase since Ascophyllum nodosum remained constant, possibly due to different abilities to deal with warmer SST. Additionally, we recorded the changes for the native Ulva spp. and introduced species of Chondrus crispus and Codium fragile found in Narragansett Bay from the 1960s to 2010s. This has ecological impacts on the fish and invertebrate species that exist in these coastal habitats and use them as nursery for juvenile stages, and economic impacts on humans who rely on the Bay for commercial and recreational uses.
Science communication using methods tied to language, audience and media tools like ArcGIS StoryMaps can be used to create a public understanding of scientific topics that are important in public policy issues. Repeated efforts can achieve scientific literacy where the public actively seeks out information on these topics and forms educated opinions. These skills are important for scientist to develop as part of their training, especially when researching topics important to public policies. However, science communication skills are not often taught in traditional curriculums at universities but are starting to be recognized. We developed 14 public outreach events on essential seaweed species in Narragansett Bay, RI, USA with community partners to evaluate various methods in science communication. This yielded interactions with 641 community members from different audiences through an educational table, lectures, and summer camp visits. Feedback showed that the touch tank with live seaweed samples was favored by 74% of participants, but those familiar with GIS applications enjoyed the online presentation in ArcGIS StoryMap the most. Effective feedback methods were short written feedback and picking their top activity by dropping a shell into a cup at the table; by contrast, we received poor responses to online surveys. It is important to evaluate and understand effective methods for science communication and what to incorporate into the training for scientist to develop communication skillsets with the public.
Drift macroalgae are rafts of floating macroalgae, Phaeophycae (brown), Rhodophyta (red) and Chlorophyta (green), that have broken off from coastal areas with epiphytic macroalga growing on them. This creates a habitat space for invertebrates and fish in moderate abundances, but higher abundances can have negative ecosystem impacts that include hypoxic zones, fish kills, and a noxious smell when rotting. The impacts of climate change are expected to increase drift macroalgae globally due to increased storms, precipitation, and sea surface temperatures (SST). We studied the presence of drift macroalgae in trawl nets at eleven stations Narragansett Bay RI, USA from 1990 to 2005 with data collected by the Rhode Island Department of Environmental Management (RIDEM). We hypothesized that there would be an increased presence of drift macroalgae in the nets throughout the time. By visualizing trends over time through heat maps, and running linear regression models, we were able to analyze long-term trend of drift macroalga in Narragansett Bay. The presence of drift macroalgae increased from 2000 to 2005 for any kind of drift algae, with more green drift than kelp drift or red and brown drift algae. Drift macroalgae in Narragansett Bay have become more common over time, which might cause problems for the commercial fishing industry and recreational users in the Bay. This will have impacts on the economic value of Narragansett Bay from the recreational sector and tourism, with drift macroalgae decomposing on beaches, and the commercial sector, with drift macroalgae getting caught in the nets for the fishing industry.
Recommended Citation
Venezia, Rebecca, "ASSESSING DISTRIBUTION AND DENSITY CHANGES OF THE ECOSYSTEM ENGINEERS, ROCKWEED AND KELP, IN NARRAGANSETT BAY, RI" (2025). Open Access Dissertations. Paper 4471.
https://digitalcommons.uri.edu/oa_diss/4471