Benthic community structure on coral reefs exposed to intensive recreational snorkeling

Impact assessment of temporary activities and events

Temporary activities and events may have significant environmental impacts. However, they are often outside the scope of environmental assessment (EA) processes. Environmental requirements in authorization processes of activities are rare, except for some major events in sensitive areas. This article analyzes, first, the environmental impacts of outdoor temporary activities and events through a literature review; all the analyzed activities may have significant negative impacts. Then, the authorization of temporary activities, and their inclusion in EA systems, in a sample of jurisdictions worldwide was analyzed. Applying EA processes is more an exception than a rule for temporary activities. The article discusses the factors that influence activities' impacts, the conflict between precaution and operation, and the benefits and drawbacks of the application of different EA schemes to temporary activities, concluding with some proposals to improve the consideration of environmental aspects in activities' authorization. Before the authorization of activities and events, their environmental impacts should be analyzed and taken into account. This can be achieved through regulations in management plans submitted to strategic EA, through screening processes, or through environmental impact assessment when significant impacts are expected. Integr Environ Assess Manag 2023;19:1320-1332. © 2023 SETAC.

Checklist of coral reef fishes of Darvel Bay, Sabah, Malaysian Coral Triangle, with a note on the biodiversity and community structure

The Darvel Bay is a large semi-enclosed bay with spectacular natural land and seascape. The inward side of the Bay has only been recently known to be an important foraging ground for the endangered, threatened and protected (ETP) elasmobranch species, such as the Whale Shark and mobulid rays. Following a recent scientific expedition, we present a checklist of the coral reef fishes of Darvel Bay. A note on the biodiversity and community structure is presented, based on our analysis using diversity indices, univariate and multivariate approaches. Seven natural coral reefs comprising two fringing reefs and five patch reefs, were surveyed at 10 m depth using underwater visual census (UVC) and baited remote underwater video station (BRUVS) methods. A diverse list of 66 species of reef fishes from 17 families is recorded. However, this is overwhelmingly dominated by the small-sized omnivorous damselfish, family Pomacentridae (62%; N = 1485 individuals). Species richness and abundance were observed to increase at sites surveyed furthest from the coast within the Bay. Significantly distinct reef fish assemblages were observed between three priori groups, based on proximity to shore (ANOSIM, R = 0.65, p < 0.05). SIMPER analysis further revealed that 22 species of the total reef fish species recorded drive 76% dissimilarities between the groups. The pattern of the reef fish communities observed, reflected as a logseries distribution model, is that commonly found in disturbed habitats or habitats characterised by restricted resources in a community, where the dominant species takes up a high proportion of available resources. The ecological indices (Shannon-Wiener Diversity Index, 2.05; Simpson Index of Diversity, 0.79; Simpson Dominance Index, 0.20; and Pielou's Evenness Index, 0.43), all reflect the relatively low diversity and uneven species distribution of the reef fish community. We conclude that the present status of the coral reef fish community dominating Darvel Bay as having undergone a rapid shift in structure following intense and rampant fishing pressure, as reported by the media.

Using 3D photogrammetry to quantify the subtle differences of coral reefs under the impacts of marine activities

Marine activities may cause the degradation of coral reefs. The composition of benthic communities and seawater quality have been commonly used as the proxies to assess the impacts of marine activities. However, these proxies may not be able to detect the subtle differences within homogeneous environment. We used photogrammetry to quantify the subtle differences of structural complexity between heavily and lightly trafficked sites at Wanlitong, southern Taiwan. Our study demonstrated that the impacts of marine activities can be detected within tens of meters through quantifying structural complexity of coral reefs. Vector ruggedness measure (VRM) is a more suitable metric than conventional linear rugosity to detect such impacts. The correlations between structural complexity and coral cover have variances while comparing with previous studies. The results show that using photogrammetry to quantify the structure of coral reefs can provide a novel aspect to evaluate the subtle differences caused by marine activities.

Recreational snorkeling activities to enhance seascape enjoyment and environmental education in the Islas Atlánticas de Galicia National Park (Spain)

Marine ecosystems provide goods and services for human well-being, and many of them correspond to cultural ecosystem services (CES). In Marine Protected Areas (MPAs), recreational activities such as snorkeling have increased recently, taking advantage of CES. However, there is a lack of educational initiatives in temperate areas to promote seascape enjoyment and pro-environmental behavior among these users, in contrast with other coastal areas such as subtropical and Caribbean ones. In this study, we have designed and implemented several snorkeling trails in Cíes Archipelago to address a better usage of CES, in a National Park (NP) context. To assess the seascape in Cíes from the point of view of the marine and sea-watching activities that take place in the NP, a new methodology was designed and implemented, including a pilot experience with snorkelers. This methodology assesses underwater aesthetic values from a multifaceted approach and allows the identification of trail-specific features that should be highlighted for increasing conservation awareness among users through environmental education and interpretation. Also, include the analysis of the users' perception and experience satisfaction, as the factors that may be influencing their pro-environmental behaviors and knowledge. Our results show that snorkeling is a good activity to learn about the seascape values, and the NP could offer it as a guided activity considering some pre and post snorkeling experience requirements.

Fluctuations in coral reef fish densities after environmental disturbances on the northern Great Barrier Reef

Global warming is predicted to increase the frequency and or severity of many disturbances including cyclones, storms, and prolonged heatwaves. The coral reef at Lizard Island, part of the Great Barrier Reef, has been recently exposed to a sequence of severe tropical cyclones (i.e., Ita in 2014 and Nathan in 2015) and a coral bleaching in the year 2016. Reef fishes are an essential part of the coral reef ecosystem, and their abundance is thus a good marker to estimate the magnitude of such disturbances. Here, we examined whether the recent disturbances at Lizard Island had an impact on the coral reef fish communities. To do this, we examined fish survey data collected before and after the disturbances for potential changes in total fish density post-disturbance. Also, by sorting fish species into 11 functional groups based on their trophic level (i.e., diet), we further explored the density changes within each functional group. Our findings showed an overall decline of 68% in fish density post-disturbance, with a significant density decrease in nine of 11 trophic groups. These nine groups were: browsers, corallivores, detritivores, excavator/scrapers, grazers, macro-invertivores, pisci-invertivores, planktivores, and spongivores. The piscivores, on the other hand, were the only "winners," wherein their density showed an increase post-disturbance. These changes within functional groups might have a further impact on the trophodynamics of the food web. In summary, our findings provide evidence that the fish assemblage on the reefs around Lizard Island was considerably affected by extreme weather events, leading to changes in the functional composition of the reef fish assemblage.

Whale Shark Tourism: Impacts on Coral Reefs in the Philippines

Reef-based tourism has been developing rapidly in recent decades yet its impacts on reef ecosystems are often overlooked. In Tan-awan, Oslob, Philippines, whale sharks are attracted to the shallow reefs where they are provisioned up to 50 tons y^-1 of feed and this phenomenon in turn attracts >300,000 y^-1 visitors. Given the intensive provisioning and concentrating tourism activities, we hypothesized that the whale shark tourism-impacted site (IS) will have greater impacts on reef degradation and higher anthropogenic nitrogen pollution level compared to its reference site (RS). Ecological surveys revealed that relative to the RS, the IS had 36% higher relative abundance of Pocillopora and Porites coral over other genera, >2.5-fold lower coral density, and 20% higher macroalgal cover, which we concluded are signs of reef degradation. Also, we conducted stable nitrogen isotope analysis on gorgonian skeletons to trace nitrogen sources at both sites through time. Although an average 1‰ isotope enrichment found in the IS relative to the RS could indicate anthropogenic nitrogen inputs in the IS, this enrichment was consistent over time and existed before the tourism developed. Despite that, we cautioned against the imminent threat of local eutrophication caused by the continued inputs of nitrogen derived from provisioning and tourism activities. In summary, this study provided the first documentation of the impacts of provisioned whale shark tourism on the local reefs in Tan-awan and established an ecological baseline for future comparisons. Such assessments can offer important information on reef health, coastal development, and tourism management.