Assessing the impact of urbanization on coastal mangrove ecosystem services and fish biodiversity in [Region] using eDNA and remote sensing

Project Abstract

Urbanization profoundly alters coastal landscapes, reshaping mangrove wetlands that function as critical interfaces among terrestrial, atmospheric, and marine systems. This study integrates environmental DNA (eDNA) and high-resolution remote sensing to quantify changes in mangrove ecosystem services and associated fish biodiversity along a [Region] coast subjected to varying intensities of urban development. We sampled water, sediment, and benthic substrates across a gradient of urban influence, complemented by satellite-derived metrics of land-use change, shoreline modification, and mangrove canopy health over the past decade. eDNA assays targeted a broad fish assemblage and key mangrove-associated taxa to detect shifts in presence–absence and relative abundance with high taxonomic resolution, enabling non-invasive monitoring across multiple spatial and temporal scales. Concurrently, remote sensing approaches employed normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), mangrove canopy height, and fragmentation indices derived from multi-temporal Landsat and Sentinel imagery to quantify habitat degradation, edge effects, and recovery trajectories. Ground-truthing included transect surveys of juvenile and adult fish catches, mangrove stand structure measurements, soil salinity, and hydrological connectivity indices to validate remotely sensed and molecular data. We applied mixed-effects models and generalized additive models to disentangle the effects of urban variables (construction density, impervious surface area, pollution proxies) from natural drivers (tidal regime, salinity, rainfall) on ecosystem services such as carbon sequestration, coastal protection, nutrient cycling, and nursery habitat provision. Our results indicate that intensified urbanization correlates with reduced mangrove canopy density, increased fragmentation, and lower sediment organic content, undermining coastal protection and carbon storage. eDNA data reveal a depletion of reef- and estuary-dependent fish species in highly urbanized zones, accompanied by a rise in tolerant generalists, suggesting biotic homogenization and disrupted trophic linkages. However, pockets of resilience emerge in well-preserved mangrove patches where hydrological connectivity remains intact and sediment accretion supports structural complexity, sustaining higher biodiversity indices and associated ecosystem services. The integration of eDNA and remote sensing proves robust for tracking rapid anthropogenic impacts, revealing lag effects between habitat alteration and detectable biodiversity responses. The study identifies threshold levels of urban pressure beyond which mangrove structural integrity and nursery function markedly decline, offering actionable targets for conservation planning, restoration prioritization, and policy formulation aimed at balancing urban development with the maintenance of ecosystem services critical to fisheries productivity and coastal resilience. These findings underscore the necessity of protecting hydrological linkages, enforcing buffer zones, and integrating molecular monitoring with geospatial analysis to inform adaptive management in urban-coastal interfaces.

Project Overview

What This Project Is About

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A straightforward, first-year-friendly look at how urban growth affects coastal mangroves and the fish that rely on them, using simple data like plant health, land use changes, and basic water observations. The project checks how nearby development might change the services mangroves provide and the variety of fish in the area.

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The Problem It Addresses

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Urban expansion can disrupt mangrove forests, which protect shorelines and support wildlife. There is a gap in understanding how these changes affect the quality of ecosystem services (like shoreline protection, water filtration) and the number and variety of fish species that depend on mangroves.

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Objectives of the Project

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1. Describe current mangrove health and extent near urban areas.
2. Assess changes in water quality and habitat structure linked to development.
3. Identify fish species present in mangrove areas and how abundances vary with urban pressure.
4. Use simple DNA sampling (eDNA) to confirm fish presence without catching them.
5. Present practical implications for conservation and urban planning.

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What You Will Do Step by Step

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1) Review local maps to identify mangrove sites near cities.

2) Collect basic field data on mangrove condition and water quality.

3) Take water samples for eDNA to detect fish species presence, with simple lab steps or partner lab.

4) Analyze photos or notes to gauge habitat changes over time.

5) Compare sites with different levels of urban impact.

6) Summarize which areas have stronger ecosystem services and richer fish life.

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Expected Outcome

Clear, easy-to-understand results showing how urbanization relates to mangrove health, service delivery, and fish biodiversity, along with practical recommendations for protecting mangroves amid growth.