Abstract

Mangroves are trees that are adapted to grow in saline or brackish environments, typically, in estuarine and coastal zones in tropical and subtropical areas. Their root complexity supports marine biodiversity by providing habitat and nursery grounds for fishes and their canopies serve as roosting and breeding sites for avian species. Additionally, roots facilitate nutrient capture through epibiont communities and trap suspended sediments, enhancing stability against high-energy weather and contributing to vertical accretion, potentially mitigating sea level rise. This study aimed to investigate how such factors as salinity, provenance, and genetic background, affect the above and below ground morphological traits of Avicennia germinans. Our study utilized sixteen maternal cohorts of A. germinans from six different sites including both range margin and core regions within the state of Florida, U.S.A. The study was a common garden experiment that was carried out over two years where plants were subject to variable salinity treatments, and a temperature regime similar to that of the range margin. We found that salinity had the strongest impact on mangrove morphology, affecting nearly all traits. Above-ground growth traits showed varied responses but were generally reduced in high salinity, with smaller biomass and shorter tree height. Below-ground growth traits were consistently negatively affected, with reduced root weight, fewer fine roots, and shorter roots. Regional effects influenced most above-ground growth traits and some below-ground traits. Range-margin cohorts were shorter, had fewer leaves, and smaller canopies than range-core cohorts. Cohort effects influenced all above-ground traits and half of below-ground traits, highlighting intrinsic differences beyond external factors. Overall, salinity and cohort had the most significant effects on mangrove growth, with high salinity negatively impacting traits critical for long-term survival. Understanding these impacts is crucial for conservation efforts, as mangrove resilience to changing environmental conditions will determine their ability to support biodiversity, protect coastlines, and adapt to rising sea levels in the face of climate change.

Awarding Institution(s)

University of Plymouth

Supervisor

Jennifer Rowntree, Richard Preziosi

Document Type

Thesis

Publication Date

2026

Embargo Period

2026-03-19

Deposit Date

March 2026

Download

Share

COinS