Physical controls on the spatial evolution of a dinoflagellate bloom in a large lake

Abstract

A set of satellite images of chlorophyll a concentration for Lake Kinneret (Israel) from the period February to April 2007 captured the temporal evolution of horizontal patchiness that developed during the typical spring bloom of the dinoflagellate Peridinium gatunense. Narrow bands of high concentration located adjacent to the shoreline at the start of the bloom were followed by progressive propagation of this high-concentration region from the shoreline toward the center of the lake as the bloom proceeded. A three-dimensional (3-D) hydrodynamic numerical model and an analytical model for a flat-bottomed elliptical basin together explain the observed phenomenon. The spatial structure of Kelvin waves, which were demonstrated to most likely be present in February and April due to resonance, produced regions of high velocity gradient, contributing to horizontal dispersion close to the shoreline. This region of high dispersion was narrow and close to the shoreline at the start of the bloom when the Burger number was relatively small, but it widened over the course of the season as the Burger number increased due to increasing stratification. In addition, an increase in the dispersion rate with time in the lake interior was inferred from numerical simulation due to increasing wind speeds and a thinner surface layer. Physical processes, in this case, horizontal dispersion as a result of both Kelvin waves and wind, can play an important role in governing the dynamics and spatial evolution of dinoflagellate blooms in lakes.

Temporal and spatial variability of the internal wave field in a lake with complex morphometry

“…0.8 for Approach 1, indicating a good match between model and field results. The RMSE and model skill estimates found in our study are of similar order to results of previous modeling studies (Jin et al 2000;Alexander and Imberger 2009;Ng et al 2011).…”

“…The RMSE obtained from Paoha Island (Table 2, Approach 2) are lower than those obtained from Simis Station (Table 2, Approach 3) and similar to those obtained from the three stations, indicating that data from the Paoha Island meteorological station are the most representative for the lake. Similar results are shown by the (Jin et al 2000;Alexander and Imberger 2009;Ng et al 2011). …”

Role of gas ebullition in the methane budget of a deep subtropical lake: What can we learn from process‐based modeling?

“…Similarly, local methanogenesis in the epilimnion linked to primary production (Grossart et al ; Tang et al ), a process that is not considered in our model, is one hypothesis to explain the observed shallow CH 4 peaks, with a further possible contribution by lateral transport from littoral zones (Hofmann et al ). In contrast to the fast lateral homogenization in the hypolimnion, the time scale for lateral mixing in the epilimnion of Lake Kinneret is on the order of 2 months (Imberger and Marti ), allowing the formation of horizontal patches of phytoplankton (Ng et al ). Similarly, high local release of CH 4 near the boundaries may cause significant lateral variation in epilimnetic CH 4 concentrations, which cannot be considered in a one‐dimensional model.…”

Research Trends in the Use of Remote Sensing for Inland Water Quality Science: Moving Towards Multidisciplinary Applications

“…Their results showed significant differences in overall trends based on land use and eco-region. Ng et al (2011) [225] and Curtarelli et al (2015) [96] both incorporated remotely sensed chl-a data into hydrologic models and found that thermal stratification and mixing were key drivers of algal bloom growth and dispersion. Work done by Rose et al (2017) [147] showed that controls on water clarity move from local to watershed scales during dry and wet years respectively.…”