Effects of recreational diving on early colonization stages of an artificial
reef in North-East Atlantic
Received: 6 March 2018 /Revised: 12 May 2018 /Accepted: 29 May 2018
Springer Science+Business Media B.V., part of Springer Nature 2018
Increasing interest for recreational SCUBA diving worldwide is raising the concern about its potential effects on marine ecosystems.
Available literature is still much focused either on impacts on coral reefs of tropical regions or on diver’s behaviour underwater. In
this study we analysed, through photo-quadrats, the benthic community composition in a section of a decommissioned Portuguese
navy ship that was sunk for touristic purposes. The ship broke down and became separated in two sections enabling a Control versus
Impact sampling design, as one section is less attractive for diving. Gorgonians (mainly belonging to the species Leptogorgia
sarmentosa and Eunicella verrucosa) were the taxa more negatively affected in the dived ship section, with smaller coverage and
size. More resilient species such as the acorn barnacle Amphibalanus amphitrite were positively correlated with the Impact samples.
In the case of the study area, according to the available data, 70% or more of the total amount of dives are now on the sunken ships.
From these results, lessons can be taken to apply on natural reefs and related management plans.
Keywords Artificial reefs
Extensive literature is available on human impacts and specif-
ically on the effects of SCUBA diving activities on coral reefs
all over the world. Direct action by divers, namely coral break-
age, has led to the degradation of coral reefs in the Red Sea
(Hawkins and Roberts 1992; Hasler and Ott 2008), Caribbean
region (Tratalos and Austin 2001; Lyons et al. 2015)and
Australia’s Great Barrier Reef (Rouphael and Inglis 1995;
Hardiman and Burgin 2010). Also, diver’s contact with the
bottom creates re-suspension of sediment that, over time, can
lead to higher stress levels for coral reefs and benthic commu-
nities (Zakai and Chadwick-Furman 2002;Barkerand
Roberts 2004; Hasler and Ott 2008).
More comprehensive studies on the effects of diving on
benthic communities as a whole are still scarce. In the U.S.
Virgin Islands, diving showed to affect the structure and health
of the reef community, with branching corals and erect
sponges being particularly affected (Chadwick-Furman
1997). In Bonaire’s reefs, a shift from massive old corals to
more fast-growing opportunistic species of branching corals
was observed, while a reduction in structural complexity of
the reef was also recorded (Hawkins et al. 1999; Lyons et al.
2015). Lyons et al. (2015) also found that no significant im-
pacts occurred on gorgonians and sponges, which the authors
justify by the higher resistance and resilience of these organ-
isms. A study in the Mediterranean Sea on bryozoan colonies
showed that the impact of divers were much more significant
on more exposed areas like boulders than on vertical walls,
affecting erect and foliose species more readily than other
bigger encrusting species (Garrabou et al. 1998).
The deployment of artificial reefs (AR) was initially direct-
ed towards fisheries management and fish stocks recovery
programs, being deployed as part of governmental manage-
ment plans since 1976 in Japan (see review by Bohnsack and
Sutherland 1985). More recently, and with the increasing pop-
ularity of recreational SCUBA diving worldwide, the deploy-
ment of ARs and namely decommissioned ships has been
proposed and already recognized as a way to reduce diving
* João Encarnação
Subnauta, Portimão, Portugal
Department of Life Sciences, Lusophone University of Humanities
and Technologies, Lisbon, Portugal
Departamento de Ciências e Engenharia do Ambiente, MARE
NOVA Faculdade de Ciências e Tecnologia, Universidade Nova de
Lisboa, Caparica, Portugal
Journal of Coastal Conservation