Wave flume facilities that are primarily designed for engineering studies are often complex and expensive to operate, and hence not ideal for long-term replicated experiments as commonly used in biology. This study describes a low-cost small wave flume that can be used for biological purposes using fresh-or seawater with or without sediment. The wave flume can be used as a mesocosm to study interactions between wave hydrodynamics and benthic organisms in aquatic ecosystems. The low-costs wave maker (< 2000 USD) allows for experimental setups which can be easily replicated and used for longer term studies; hence the term wave mesocosm. Waves were generated with a pneumatic piston and wave heights ranged between 3 and 6 cm. Maximum orbital flow velocities ranged between 10 and 50 cm s −1 representing shallow coastal areas with a short fetch. The system can generate both regular waves (i.e., the wave period and orbital velocity remains constant), using a wave absorber, and irregular waves (i.e., varying wave period and orbital velocity) using a fast push and slow pull motion of the wave paddle. This wave mesocosm system is particularly useful in biogeomorphology to quantify interactions between organisms, sediment, and hydrodynamics and for aquatic ecologist aiming to simulate realistic bed shear stress where short-and long-term experiments (weeks-months) can be replicated.

Posidonia oceanica meadows are ecosystem engineers that play several roles in marine environment maintenance. In this sense, monitoring of the spatial distribution and health status of their meadows is key to make decisions about protecting them against their degradation. With the aim of checking the ability of a simple low-cost acoustic method to acquire information about the state of P. oceanica meadows as ecosystem indicators, ground-truthing and acoustic data were acquired over several of these meadows on the Levantine coast of Spain. A 200 kHz side scan sonar in a vertical configuration was used to automatically estimate shoot density, canopy height and cover of the meadows. The wide athwartship angle of the transducer together with its low cost and user friendliness entail the main advantages of this system and configuration: both improved beam path and detection invariance against boat rolling. The results show that canopy height can be measured acoustically. Furthermore, the accumulated intensity of the echoes from P. oceanica in the first 30 centimeters above the bottom is indirectly related to shoot density and cover, showing a relation that should be studied deeply.