Physiological Responses of the Submerged Macrophyte Stuckenia pectinata to High Salinity and Irradiance Stress to Assess Eutrophication Management and Climatic Effects: An Integrative Approach

Lamprini Malea,Sotiris Orfanidis,Athanasios Exadactylos,Konstantinia Nakou,Apostolos Papadimitriou

doi:10.3390/w13121706

Lamprini Malea, Sotiris Orfanidis + Show 3 more

Open Access

https://doi.org/10.3390/w13121706

Copy DOI

Abstract

Stuckenia pectinata, a submerged macrophyte of eutrophic to hyper-eutrophic fresh to brackish waters, faces management and climatic-forced increment of salinity and irradiance in Vistonis Lake (Greece) that may endanger its existence and the ecosystem functioning. A pre-acclimated clone under low irradiance and salinity conditions was treated to understand the effects of high salinity and irradiance on a suite of subcellular (chlorophyll a fluorescence kinetics and JIP-test, and chlorophyll content) to organismal (relative growth rate—RGR) physiological parameters. The responses to high irradiance indicated the plant’s great photo-acclimation potential to regulate the number and size of the reaction centers and the photosynthetic electron transport chain by dissipation of the excess energy to heat. A statistically significant interaction (p < 0.01) of salinity and irradiance on Chl a, b content indicated acclimation potential through adjusting the Chl a, b contents. However, no significant (p > 0.05) difference was observed on Chl a/b ratio and the RGR, indicating the species’ potential to become acclimatized by reallocating resources to compensate for growth. Thus, the regulation of photosynthetic pigment content and photosystem II performance consisted of the primary growth strategy to present and future high salinity and irradiance stressful conditions due to eutrophication management and the ongoing climatic changes.

Highlights

Submerged macrophytes are aquatic plants of remarkable phenotypic plasticity [1]that grow across contrasting conditions, from pristine to degraded lakes, estuaries, and coastal lagoons [2,3]
Each kinetic is the average of six replicates, after each of the kinetics Ft = f(t) was normalized on its initial value; i.e., the averages are plotted as Ft /F0 = f(t)
This study focused on long-term photo acclimation monitored by changes in the number and size of the reaction centers and the photosynthetic electron transport chain

Summary

Introduction

Submerged macrophytes are aquatic plants of remarkable phenotypic plasticity [1]. That grow across contrasting conditions, from pristine to degraded lakes, estuaries, and coastal lagoons [2,3] They provide food and habitat for invertebrates, larvae and juvenile fishes [4]. They play a crucial role in water quality improvement by stabilizing the sediments [2]. They take up excess nitrogen and phosphorus and excrete allelopathic substances [5], contributing to reductions in nuisance algal blooms [6]. Because the plant is food for waterfowl [12], it spreads over long distances [13] and in different environments, where it survives through acclimatization by means of plastic phenotypic responses [1,14,15] and genetic differentiation [16,17]

Objectives

Methods

Results

Discussion

Conclusion