Do invasive quagga mussels alter CO2 dynamics in the Laurentian Great Lakes?

Peng Lin,Laodong Guo

doi:10.1038/srep39078

Abstract

The Laurentian Great Lakes have experienced unprecedented ecological and environmental changes, especially after the introduction of invasive quagga mussel (Dreissena rostriformis bugensis). While impacts on ecological functions have been widely recognized, the response of carbon dynamics to invasive species remains largely unknown. We report new CO2 data showing significant increases in pCO2 (up to 800 μatm in Lake Michigan) and CO2 emission fluxes in most of the Great Lakes compared to those prior to or during the early stage of the colonization of invasive quagga mussels. The increased CO2 supersaturation is most prominent in Lakes Huron and Michigan, followed by Lakes Ontario and Erie, but no evident change was observed in Lake Superior. This trend mirrors the infestation extent of invasive quagga mussels in the Great Lakes and is consistent with the decline in primary production and increase in water clarity observed pre- and post-Dreissena introduction, revealing a close linkage between invasive species and carbon dynamics. The Great Lakes have become a significant CO2 source to the atmosphere, emitting >7.7 ± 1.0 Tg-C annually, which is higher than the organic carbon burial rate in global inland-seas and attesting to the significant role of the Laurentian Great Lakes in regional/global CO2 budget and cycling.

Highlights

Levels of carbon dioxide (CO2) can serve as an indicator of autotrophic or heterotrophic nature of an aquatic environment[1], and can be an important parameter to elucidate calcification and potential pH changes in a water body[2,3,4]
The Laurentian Great Lakes can be characterized as a high-pH and high-carbonate ecosystem Lake Superior had a relatively lower pH and carbonate abundance compared to the other Great Lakes (Fig. 2 and Table 1)
Concentrations of dissolved inorganic carbon (DIC) and total alkalinity (TA) typically exceeded the threshold of 1000 μmol/kg except for Lake Superior (Table 1)

Summary

Introduction

Levels of carbon dioxide (CO2) can serve as an indicator of autotrophic or heterotrophic nature of an aquatic environment[1], and can be an important parameter to elucidate calcification and potential pH changes in a water body[2,3,4]. Carbon cycling and magnitude of CO2 fluxes across the air-water interface in lakes and inland waters have received increasing attention[15,16,17,18], studies on carbon dynamics in the Great Lakes remain scarce[17,19]. Specific changes in carbon dynamics, as well as the impacts and biogeochemical consequences after the colonization of invasive quagga mussels in the Laurentian Great Lakes remain poorly understood. To examine the response of carbon dynamics to the introduction of invasive quagga mussels and linkages between invasive species and changes in biogeochemical cycling, open lake water samples were collected from all of the Laurentian Great Lakes, including Lake Superior, Lake Michigan, Lake Huron, Lake Erie and Lake Ontario, www.nature.com/scientificreports/. In addition to water isotopic composition (δ2H and δ18O), total alkalinity (TA), dissolved inorganic carbon (DIC), and pH were measured prior to the evaluation of the partial pressure of CO2 (pCO2) and air-water CO2 fluxes

Methods

Results

Conclusion