Use of a high-resolution profiling sonar and a towed video camera to map a Zostera marina bed,Solent, UK

Seagrasses are flowering plants that develop into extensive underwater meadows and play a key role in the coastal ecosystem. In the last few years, several techniques have been developed to map and monitor seagrass beds in order to protect them. Here, we present the results of a survey using a profiling sonar, the Sediment Imager Sonar (SIS) and a towed video sledge to study a Zostera marina bed in the Solent, southern UK. The survey aimed to test the instruments for seagrass detection and to describe the area for the first time.     

Photosynthetic and metabolic responses of eelgrass Zostera marina L. to short-term high-temperature exposure

In recent years, extreme heat events have occurred worldwide and the ocean temperature has been rising, causing stress on the photosynthesis and growth of seagrass. Metabolomics enables detection of metabolic changes under environmental stress. In this study, the photosynthetic physiology and metabolic changes of the eelgrass Zostera marina L. in response to 48 h exposure to 32°C were investigated. The results showed that high temperature induced signi?cant inhibition of photosynthetic effciency(Δ F/F′ m)(23.9%lower than the control), enhanced respiration(58.3% higher), and decreased carbohydrate decomposition products and tricarboxylic acid(TCA) cycle intermediate products, indicating that the energy supply of the eelgrass may be insuffcient at high temperature. In addition, high temperature decreased stearic acid and linoleic acid in eelgrass, suggesting the composition of the membrane system of eelgrass may change at high temperature and implying that high temperature may cause the membrane system to be unstable.