Program Results

Introduction to the event

Phytoplankton and prokaryotes (bacteria and archaea) form the foundation of ocean ecosystems and play a central role in carbon cycling. Their populations can shift rapidly, but such changes are often missed with traditional, low-frequency sampling. To better capture these dynamics, we collaborated with professors from National Taiwan University (NTU) and National Taiwan Ocean University (NTOU) to collect daily water samples for 100 consecutive days at a coastal site between September and December 2024.

To characterize the entire microbial community, we developed a new molecular approach that combines amplicon sequencing with a universal primer set (515Y-926R) targeting both 16S and 18S rRNA genes, together with spike-in genomic standards. This highly efficient method provides absolute abundances of all major microbial groups—across three domains of life—from a single PCR reaction. Using this approach, we were able to precisely track when and how community shifts occurred.

Our observations revealed two major environmental patterns: (1) a gradual seasonal transition from warm, nutrient-poor waters to cooler, nutrient-rich conditions, and (2) a sudden disturbance in October when a typhoon sharply increased nutrient levels. Under normal conditions, phytoplankton and prokaryotes generally shifted in parallel. However, during the typhoon, their responses became desynchronized Phytoplankton changed first, while bacterial and archaeal communities lagged behind, causing a temporary mismatch in their dynamics.

This study demonstrates the power of combining high-frequency sampling with a highly efficient molecular method to capture both gradual seasonal transitions and sudden environmental disturbances. Our findings highlight that while phytoplankton and prokaryotes are tightly linked, their responses are not always synchronized. This finding can provide important implications for predicting how marine ecosystems respond to environmental change.

Fig 1. Sampling location

Fig 2. Principal component analysis (PCA) of environmental variables, including temperature, chlorophyll-a concentration (Chla), nitrite, nitrate, phosphate, and silicate. Each dot represents the environmental conditions on a given sampling day, color-coded on a blue gradient: dark blue indicates the start of the 100-day sampling period, while light blue indicates the end. Red bars indicate dates when sampling was not conducted due to a typhoon. 

Figure 3. Principal component analysis (PCA) of phytoplankton and prokaryotic communities, illustrating their community dynacmis. Each dot represents the community composition on a given sampling day. Red bars indicate dates when sampling was not conducted due to a typhoon.