Semester of Graduation

May 2020

Degree

Master of Science (MS)

Department

Renewable Natural Resources

Document Type

Thesis

Abstract

Harmful algal blooms (HABs) are increasing globally in frequency, persistence, and geographic extent. HABs pose a threat to economic stability, and ecosystem and human health. To date no incidences of marine toxins produced by phytoplankton have been recorded in Mozambique, which may be due to the absence of a monitoring program and general awareness of the potential threat. This study is the first documentation of the occurrence of a neurotoxin, domoic acid (DA), produced by the diatom genus Pseudo-nitzschia spp. along the east coast of Africa. The coast of Inhambane Province is a biodiversity hotspot where year-round Rhincodon typus (whale shark) sightings are among the highest in the world, supporting an emerging ecotourism industry. Links between primary productivity and biodiversity in this area have not previously been considered or reported. My research focused on identifying environmental factors, specifically nutrients, influencing coastal productivity and DA concentrations and highlights variations within the system across four regions during May-August 2018. During this time, the coastal phytoplankton community was diatom-dominated, with high abundances of Pseudo-nitzschia spp. which were influenced by nutrient pulses resulting from wind-driven upwelling. In late July 2018, primary production was enhanced and corresponded with a peak in DA located within a biodiversity hotspot for Rhincodon typus (whale shark). Increases in DA concentration were correlated to phosphorus limitation. Domoic acid was also found to be present in mesozooplankton samples, providing evidence for trophic transfer of the toxin and the potential for bioaccumulation within a system, serving as a vector for higher trophic level organisms. Continued and comprehensive monitoring along southern Mozambique would provide critical information to develop predictive models to assess ecosystem and human health threats and impacts to the local economy from marine toxins under challenges posed by global change.

Committee Chair

Errera, Reagan

Share

COinS