Light is a factor that influences marine organisms in a multitude of ways.
A recent surge in LED lighting to be used at coastal residential sites and industrial areas (oil rigs) is illuminating marine ecosystems at night. Set to peak in 2020, it’s hoped that CO2 emissions and costs will be reduced as a result of their introduc-tion.
Stuart Jenkins from the School of Ocean Sciences at Bangor University and his team measured the impacts of this lighting on sessile and mobile invertebrates. Their findings produced mixed results.
For 12 weeks in July 2013, a floating raft was deployed in the Menai Strait, Wales, suspending wooden boards in the water column (at 20cm depth). The panels were either: not artificially lit at all (control), 19 Lux (a unit of illuminance) or 30 Lux using white LED lights at the water’s surface.
It was found that the colonization of a colonial ascidian (a sea squirt), (Botrylloides leachii) and a hydroid (Plumularia setacea) was dramatically reduced in both light treatments. However, the abundance of tube-building polychaete worms increased 3 fold under the LED light treatments. These worms are not too dissimilar in their ecology from terrestrial worms; they help stabilize the sediment (from wave action) and improve its mineral quality. Functioning as ecosystem engineers, benthic invertebrates such as these polychaetes support local fisheries, provide coastal protection and attract tourism. Changes in the fundamental ecology and community composition of these ecosystems will ultimately alter other organisms further up the food chain.
As the use of LED lights is set to skyrocket in the next 5 years, recruitment of sessile invertebrates and community composition of epifaunal mobile invertebrates will be measured in North Wales and around the World with intensifying scrutiny to decipher the future ecological impacts of this growing industry.