The Correlation between Prorocentrum donghaiense Blooms and the Taiwan Warm Current in the East China Sea - Evidence for the “Pelagic Seed Bank” Hypothesis

Xinfeng Dai,Douding Lu,Ping Xia,Piaoxia He,Hongxia Wang,Dongsheng Zhang,Weibing Guan,Senjie Lin

doi:10.1371/journal.pone.0064188

Abstract

During the last two decades, large-scale high biomass algal blooms of the dinoflagellate Prorocentrum donghaiense Lu have occurred frequently in the East China Sea (ECS). The role of increasing nutrient concentrations in driving those blooms is well-established, but the source population that initiates them is poorly understood. We hypothesized that the front of Taiwan Warm Current (TWC) may serve as a ‘seed bank’ that initiates P. donghaiense blooms in the ECS, as the physiochemical conditions in the TWC are suitable for the growth of P. donghaiense. In order to test this hypothesis, two surveys at different spatio-temporal scales were conducted in 2010 and 2011. We found a strong correlation in space and time between the abundance of P. donghaiense and the TWC. The spatial extent of the P. donghaiense bloom coincided with the TWC front in both 2010 and 2011. During the early development of the blooms, P. donghaiense concentration was highest at the TWC front, and then the bloom mass shifted inshore over the course of our 2011 survey. The TWC also moved inshore, albeit after the appearance of P. donghaiense. Overall, these results support our hypothesis that P. donghaiense blooms develop from the population at the TWC front in the ECS, suggesting the role of the ocean current front as a seed bank to dinoflagellate blooms.

Highlights

Large-scale high biomass algal blooms of the dinoflagellate Prorocentrum donghaiense Lu have occurred frequently in the East China Sea (ECS) over the last two decades
Large-scale P. donghaiense blooms in the ECS are affected by multiple factors including eutrophication from human activities [5]
We highlighted the role of the Taiwan Warm Current (TWC) front as a ‘‘pelagic seed bank’’ to inshore P. donghaiense blooms

Summary

Introduction

Large-scale high biomass algal blooms of the dinoflagellate Prorocentrum donghaiense Lu have occurred frequently in the East China Sea (ECS) over the last two decades. These blooms are massive, sometimes extending over thousands of square kilometers, and can persist for nearly one month [1,2]. The proposed mechanism is in contrast to the initiation mechanism that has been described for cyst-forming dinoflagellate species (e.g. Alexandrium fundyense) that are inoculated through the germination of their benthic cysts [7,8] No such cyst stage has been described for P. donghaiense [4]. We tested the ‘‘pelagic seed bank’’ hypothesis for the initiation of P. donghaiense blooms in the ECS via introduction from the TWC front. The bloom pattern and development were examined in the surveys

Results

Discussion

Materials and Methods