ABSTRACT. Artificial reefs represent effective ecosystems for fish restocking but they are also extremely delicate and sensitive environments as they represent hot-spots for recreational divers. For this reason, the impact of recreational diving on artificial reefs should be taken in consideration as unexperienced divers and underwater photographers can strongly affect benthic communities. The aim of this study was to assess the effect of recreational diving on the macroalgae coverage of the shipwreck “Zenobia” in Larnaka (Cyprus). The “Zenobia” is an excellent example of artificial reef affected and partially damaged by anthropogenic activities, as it represent one of the 10 best shipwreck and one of the 25 best diving site in the world. The macroalgae coverage, here considered as indicator of physical damage caused by recreational divers, was compared in three transects on the exposed side of the shipwreck, using the photoquadrats technique and the Coral Point Count Excel extension software. This study remarks the importance of digital imaging samplings in habitat characterization since these techniques offer an excellent compromise between dive time and data accuracy, offering an excellent alternative to destructive sampling. In addition, this study supports the effectiveness of digital image analysis software, such as CPCe, which couple versatility, accuracy, and simplicity, making them necessary and indispensable tools in scientific diving.
During my MSc project, in Cyprus, I had the privilege to undertake one of the first official research on the Zenobia shipwreck.
Located 800m far from Larnaca harbour, the Zenobia shipwreck is one of the 10 best shipwrecks in the world and (one of) the most visited in the Mediterranean Sea. This almost 200m long shipwreck offers a unique diving experience for divers of any level of experience, thanks mainly to its proximity to the coast, to the depth accessible to the less experienced divers, but offering also a wide range of technical diving scenarios, satisfying technical divers, photographers and videographers, rebreathers, and professional wreck divers.
The Zenobia shipwreck sits on a sandy bottom, acting perfectly as unintentional artificial reef, providing an excellent alternative to the lower diversity habitat it sits in. Increasing enormously the complexity, heterogeneity and tridimensionality of the surrounding soft-bottom habitat, this shipwreck provides a wide range of benefits for flora and fauna: provision of settlement space for benthic organisms and larvae, provision of shelter and refuge from predation, buffering physical stress, increasing the availability of food and feed efficiency, and much more. As a result, the Zenobia shipwreck supports a very wide range of benthic, nectonic and planktonic organisms, attracting a large amount of tourists every year.
The main purpose of my research was assessing the impact of recreational diving on the benthic community of the Zenobia shipwreck, mostly in terms of physical mechanical damanges of encrusting organisms.
The method used was the photo-quadrat technique, developed and shaped after a series of pre-surveys, using a fit-to-purpose frame, and coupled with a combination of continuous, random and systematic sampling methods in different areas of the shipwreck susceptible of different impact level. Each picture was then processed using the software Coral Point Count Excel extention, from Nova Southeastern University, and a number of data have been processed in order to assess the level of pressure the shipwreck is experiencing.
This research was then finalized, few years later, by the publication of a peer-reviewed paper.