Ecosystem Health in Guánica Bay and La Parguera, Puerto Rico: Remote Sensing of Ocean Color & Coral Metal Analysis
In this study, Howe (2020) assessed coastal ecosystem health by combining remote sensing (via recent ocean color imagery) with chemical analysis of coral tissues and surface sediments in Guánica Bay and La Parguera in Puerto Rico.
Key takeaways:
Remote Insights: Elevated chlorophyll‑a (Chl‑a) concentrations in 2019—observed via sea color sensors at both virtual stations and pixel-level samples—correlated with increased nutrient runoff during a wetter dry season.
Heavy Metal Signals: Coral tissues (specifically Montastraea cavernosa) showed high copper (103 ppm), exceeding the 69 ppm threshold known to impair coral fertilization. Zinc levels were elevated compared to previous baselines but not considered toxic.
Sediment Status: Surface sediments generally presented low contamination. However, Geoaccumulation Index (Iₙₑ) results showed significant copper accumulation—especially near urbanized zones like Baul (Iₙₑ > 2)—mirroring high Chl‑a levels and indicating moderate-to-strong contamination.
Human Influence: The findings suggest anthropogenic runoff during atypical precipitation events may harm coral health, particularly through elevated copper exposure.
Significance: This research offers a valuable update on coral and sediment contaminant levels in Puerto Rican reefs and highlights the importance of integrating remote sensing and chemical monitoring to capture shifts in ecosystem health under climate and human stressors.
For access to this thesis: https://academicworks.cuny.edu/cc_etds_theses/846/
