In situ effects of human disturbances on coral reef-fish assemblage structure: temporary and persisting changes are reflected as a result of intensive tourism

Abstract

Non-lethal human disturbances are often drivers of change in animal population and community structure. To gauge their severity, short-term behaviour (e.g. avoidance and habituation) has been argued to be a sensitive measure. However, many of these behavioural changes may occur only if disturbance-free habitat is readily accessible. In coral-reef fish, we tested whether human disturbances from intensive (i.e. loud music, swimming, snorkelling, splashing and fish feeding by numerous visitors) tourist visitations resulted in assemblage structure shifts led by shortterm behaviour. We monitored fish assemblage before, during and after tourist visitations to monitor changes associated with behaviour. Additionally, we monitored two adjacent reefs not visited by tourists because of difficult approach by boat. We posited that if short-term benefits of relocating to disturbance-free habitat outweigh the costs of tolerating disturbances, fish assemblage structure should shift along with tourist visitation levels. By contrast, if sensitive species are unable or unwilling to relocate, we predicted greater levels of assemblage heterogeneity between the visited and control reefs. Our results showed that in situ human visitations led to significant shifts in assemblage structure, resulting from short-term behavioural changes. Additionally, we showed significant between-reefs differences, whereby control reefs were characterised by higher species richness, larger fish sizes and variations in relative trophic guild prevalence. Our results suggest that short-term relocations to adjacent disturbance-free reefs may not mitigate the effects of human disturbances.

To Feed or Not to Feed? Coral Reef Fish Responses to Artificial Feeding and Stakeholder Perceptions in the Aitutaki Lagoon, Cook Islands

“…Quantifying the fish density, fish species composition (by feeding groups), and taxonomic richness is important because of the ecological relevance of these metrics, but also because they are important contributors to the aesthetic value of snorkeling tours for tourists. Fish density and taxonomic richness were quantified using stationary underwater visual censuses (Bohnsack and Bannerot, 1986), consistently conducted by the same observer (NP) to avoid inter-observer bias (Albuquerque et al, 2015). A 3 m radius (area of 28.27 m 2 ) was observed from a fixed position on the sea surface for 15 min while counting all active, non-cryptic fish.…”

Distribuição espacial dos visitantes na piscina de visitação do parque natural municipal do recife de fora, Porto Seguro (Bahia)

“…Diversas linhas de pesquisa têm sido conduzidas no PNMRF recentemente, tais como classificação do habitat bentônico (Seoane et al, 2012), levantamento da estrutura da ictiofauna (Chaves et al, 2010), padrão de sedimentação (Costa et al, 2011) e efeitos da acidificação do oceano sobre a meiofauna (Sarmento et al, 2015). No tocante ao turismo, alguns estudos têm avaliado o impacto dessa atividade em ambientes recifais brasileiros (Ilarri et al, 2008;Sarmento et al, 2011;Sarmento and Santos, 2012;Chaves et al, 2013;Albuquerque et al, 2015;Giglio et al 2015). No entanto, ainda não há estudos voltados para a avaliação do turismo no PNMRF.…”

Conservation of Brazilian coral reefs in the Southwest Atlantic Ocean: a change of approach

“…The area is frequently affected by vessels and divers, who can directly interact with the environment, thereby breaking coral colonies and damaging the local reef system. High levels of scuba diving activity may cause changes in the structure of fish schools, short-term behavioral changes and a decrease in the richness and abundance of various species (Albuquerque et al, 2015). However, measures to intensify supervision in Marine Protected Areas (MPAs), to define the local load capacity and to limit the daily number of divers, in addition to promoting visitor awareness, can mitigate the impact of tourism on Brazilian reef environments (Giglio et al, 2015).…”

“…This effort began with a more comprehensive description of reef formations (Castro & Pires, 2001), starting with a string of studies ranging from an analysis of the main threat vectors, such as unregulated tourism (Ilarri et al, 2008;Sarmento & Santos, 2012;Albuquerque et al, 2015), overfishing and destructive fishing methods (Floeter et al, 2006;Francini-Filho & Moura, 2008a;Batista et al, 2014), coastal pollution and sedimentation (Costa Jr. et al, 2008;Segal et al, 2008;Silva et al, 2013), introduction of species (Creed, 2006;Luiz et al, 2013;Costa et al, 2014) and climate change (Leão et al, 2010;, to studies focusing on planning for conservation Loiola et al, 2014;Santos & Schiavetti, 2014;Vilar et al, 2015) and new habitats (Amado-Filho et al, 2012;Bastos et al, 2013).…”