Exceptionally high but still growing predatory reef fish biomass after 23 years of protection in a Marine Protected Area

Intense scuba diving does not alter activity patterns of predatory reef fish: Evidence from a protected tourism hotspot

The rise of nature-based tourism has provided a new avenue for disturbing animal behaviour, especially in protected areas. One of the most important tourism sectors in aquatic environments is scuba diving, an activity considered sustainable given its non-extractive nature and capability of bringing relevant socio-economic benefits to local communities. However, knowledge about its impact on the activity patterns of aquatic animals is still scarce. Here, we used biotelemetry techniques to assess the importance of scuba diving in modulating the activity patterns of the dusky grouper (Epinephelus marginatus, Lowe, 1834), a marine predatory fish of high interest for fishing and tourism. We implemented Hidden Markov Models (HMMs) on high-resolution acceleration data using a temporal and spatial control while controlling for a set of environmental variables (i.e. photoperiod, time-of-day, moon phase, temperature, wave height, and intensity and direction of marine currents) within a multiple-use marine protected area, and diving tourism hot-spot, of the western Mediterranean Sea. Our results underlined the more decisive influence of environmental-related stressors on the activity patterns of the dusky grouper compared to the impact of scuba diving. A high heterogeneity existed in the response against most of the stressors, including the presence of scuba divers. Overall, the activity of dusky grouper was higher at night than at day, showing a positive relationship with wave height, water temperature, and current intensity and a negative one with the moon phase. Remarkably, our findings, based on novel biotelemetry tools, differed substantially from the common wisdom accepted for this species. In conclusion, there is no clear evidence of scuba divers influence on the general activity patterns of the dusky grouper. Beyond their relevance from an ecological perspective, these results provide useful insights for the sustainable management of coastal resources, suggesting that scuba diving, when properly carried out, can represent an important sector to foster for the blue growth of coastal communities.

Coral reef fish assemblages exhibit signs of depletion in two protected areas from the eastern of Los Canarreos archipelago (Cuba, Caribbean Sea)

Understanding the impact of marine protected areas on the distribution and composition of fishes is key to the protection and management of coral reef ecosystems, and especially for fish-based activities such as SCUBA diving and recreational fishing. The aim of this research is to compare the ichthyofauna structure in three areas in the eastern part of Los Canarreos archipelago in Cuba with different management schemes: Cayo Campos-Cayo Rosario Fauna Refuge (CCCR), Cayo Largo Ecological Reserve (CL) and non-protected area (nMPA), and considering habitat differences and depth variation. A total of 131 video transects were conducted using diver operated stereo-video (stereo-DOV) in November, 2015 in backreef and forereef along the CCCR, CL and the adjacent nMPA. We recorded 84 species and 27 functional groups suggesting high complementarity of functions. Several multispecies schools were observed along surveys, which explain the biomass peaks in some sites, mainly for Lutjanidae, Haemulidae and Carangidae. A concerning issue was the bare representation of critical functional groups and threatened species. The effect of sites nested within habitats was significant and the most important driver structuring fish assemblages, while MPA condition was not evident. Favorable habitat features (habitat heterogeneity and surrounding coastal ecosystems) are likely enhancing fish assemblages and counteracting the effects of pouching derived from insufficient management. We recommend immediate actions within a strategy of precautionary management including, but not limited to, the appointment of staff for the administration of CL, frequent monitoring and effective enforcement.

Quotas regulation is necessary but not sufficient to mitigate the impact of SCUBA diving in a highly visited marine protected area

When effectively managed, Marine Protected Areas (MPAs) can produce wide ecosystem benefits that can foster, directly and indirectly, local economies. Tourism is one of the sectors mainly benefited by the effect of conservation. SCUBA diving represents an important tourism activity, especially in the context of MPAs, where it is one of the few activities often fostered rather than limited, for its capacity to integrate environmental and socio-economic sustainability. However, SCUBA diving can also produce negative impacts on the environment when tourism frequentation exceeds a sustainable threshold, these potentially generating negative effects on the sector itself. In this study, we (1) investigated the impact of SCUBA diving in one of the most frequented diving areas of the Mediterranean Sea (Cabo de Palos - Islas Hormigas marine reserve), and (2) assessed the potential benefits over time related to the adoption of a regulation change for the diving activity (i.e., formally adoption of diving quotas). Specifically, we compared demographic (density of alive and dead colonies) and morphometric (height, width and complexity) characteristics of the false coral (Myriapora truncata) between dived and fully protected (non-dived) locations over four diving seasons (one before and three after the change in diving quotas). The density of alive colonies of the false coral was, on average, six times lower in dived locations compared to controls, highlighting a clear impact of SCUBA diving (consistent over time). Colonies were also significantly smaller in dived locations. The diving quotas produced a significant reduction of the ratio dead/total colonies in the dived locations soon after their adoption, but these benefits disappeared over the following years, possibly due to a gradual decline in operators' and divers' observance and concern, rather than an increasing number of dives. This suggests that the adoption of effective regulations is crucial for the environmental sustainability of diving tourism in protected areas and can provide positive effects, but an effort is needed to ensure that compliance is consistent over time, and that low-impact diving practices are adopted by this important recreational sector.

Drivers of ecological effectiveness of marine protected areas: A meta-analytic approach from the Southwestern Atlantic Ocean (Brazil)

With the rapid global increase in the number and extent of marine protected areas (MPAs), there is a need for methods that enable an assessment of their actual contribution to biodiversity conservation. In Brazil, where MPAs have been designated to replenish biodiversity, there is a lack of regional-scale analysis of MPA impacts and the factors related to positive ecological change. This study aims to quantify the magnitude of the ecological effects of Brazilian MPAs and test whether some study and MPA characteristics (e.g., taxonomic group studied, exploitation level of species, MPA area, protection time, management effectiveness, level of connectedness, etc.) were underlying factors associated with their performance. We conducted a structured search in a database of scientific articles, selecting comparative studies of direct biodiversity metrics inside and outside MPAs offering different protection levels (i.e., fully- or partially-protected MPAs) or within MPAs with distinct zones. We then carried out a meta-analysis based on 424 observations found in 18 articles. Averaged across all studies, we found that MPAs had a 17% increase in the abundance of species, length of individuals, and community diversity. When compared to open-access areas, fully-protected MPAs increased biodiversity by 45%. However, MPAs offering partial protection had variable effects, ranging from significant positive to significant negative effects. MPA effects depended on the taxonomic group and exploitation level of species, with the strongest positive effects seen on exploited fish species and benthic invertebrates. Partially-protected MPAs that reported strong positive effects required long time of protection (>15years) and high level of connectivity. Conversely, fully-protected MPAs (i.e., no-take ones) could be effective even when small, under intense fishing pressure in their surroundings, and regardless of their level of connectivity. We used the Brazilian MPAs as a case study, but these results can contribute to a more comprehensive assessment of the association between ecological impacts of MPAs and drivers of conservation success, and offer key information to consolidate MPA networks that sustain biodiversity.