A citizen science approach: A detailed ecological assessment of subtropical reefs at point lookout, Australia

Subtropical reefs provide an important habitat for flora and fauna, and proper monitoring is required for conservation. Monitoring these exposed and submerged reefs is challenging and available resources are limited. Citizen science is increasing in momentum, as an applied research tool and in the variety of monitoring approaches adopted. This paper aims to demonstrate an ecological assessment and mapping approach that incorporates both top-down (volunteer marine scientists) and bottom-up (divers/community) engagement aspects of citizen science, applied at a subtropical reef at Point Lookout, Southeast Queensland, Australia. Marine scientists trained fifty citizen scientists in survey techniques that included mapping of habitat features, recording of substrate, fish and invertebrate composition, and quantifying impacts (e.g., occurrence of substrate damage, presence of litter). In 2014 these volunteers conducted four seasonal surveys along semi-permanent transects, at five sites, across three reefs. The project presented is a model on how citizen science can be conducted in a marine environment through collaboration of volunteer researchers, non-researchers and local marine authorities. Significant differences in coral and algal cover were observed among the three sites, while fluctuations in algal cover were also observed seasonally. Differences in fish assemblages were apparent among sites and seasons, with subtropical fish groups observed more commonly in colder seasons. The least physical damage occurred in the most exposed sites (Flat Rock) within the highly protected marine park zones. The broad range of data collected through this top-down/bottomup approach to citizen science exemplifies the projects' value and application for identifying ecosystem trends or patterns. The results of the project support natural resource and marine park management, providing a valuable contribution to existing scientific knowledge and the conservation of local reefs

Refugia under threat: Mass bleaching of coral assemblages in high‐latitude eastern Australia

Environmental anomalies that trigger adverse physiological responses and mortality are occurring with increasing frequency due to climate change. At species' range peripheries, environmental anomalies are particularly concerning because species often exist at their environmental tolerance limits and may not be able to migrate to escape unfavourable conditions. Here, we investigated the bleaching response and mortality of 14 coral genera across high‐latitude eastern Australia during a global heat stress event in 2016. We evaluated whether the severity of assemblage‐scale and genus‐level bleaching responses was associated with cumulative heat stress and/or local environmental history, including long‐term mean temperatures during the hottest month of each year (SSTLTMAX), and annual fluctuations in water temperature (SSTVAR) and solar irradiance (PARZVAR). The most severely‐bleached genera included species that were either endemic to the region (Pocillopora aliciae) or rare in the tropics (e.g. Porites heronensis). Pocillopora spp., in particular, showed high rates of immediate mortality. Bleaching severity of Pocillopora was high where SSTLTMAX was low or PARZVAR was high, whereas bleaching severity of Porites was directly associated with cumulative heat stress. While many tropical Acropora species are extremely vulnerable to bleaching, the Acropora species common at high latitudes, such as A. glauca and A. solitaryensis, showed little incidence of bleaching and immediate mortality. Two other regionally‐abundant genera, Goniastrea and Turbinaria, were also largely unaffected by the thermal anomaly. The severity of assemblage‐scale bleaching responses was poorly explained by the environmental parameters we examined. Instead, the severity of assemblage‐scale bleaching was associated with local differences in species abundance and taxon‐specific bleaching responses. The marked taxonomic disparity in bleaching severity, coupled with high mortality of high‐latitude endemics, point to climate‐driven simplification of assemblage structures and progressive homogenisation of reef functions at these high‐latitude locations

Biogeographical and cross-shelf patterns of reef fish assemblages in a transition zone

Transition zones have complex patterns of biogeography and biodiversity which require consideration in conservation planning. Cross-shelf patterns of reef fish assemblage structure and biogeographic representation were determined for the Solitary Islands Marine Park (SIMP), positioned in a tropical-temperate overlap on the east coast of Australia. Sixty-eight sites were surveyed on shallow (\u3c25 m) reefs across an inshore–offshore gradient, using timed counts. Tropical taxa were most prevalent, comprising 50% of the 254 species recorded. Australian endemics accounted for 23% of species, with east coast endemics (14%) predominating. There was a strong cross-shelf gradient, with species richness increasing offshore. There was also a distinct biogeographical gradient with the proportion of temperate species decreasing and tropical species increasing with increasing distance from shore. This gradient was similar for endemic and cosmopolitan species as many of the endemics were temperate or subtropical, and many of the tropical species were widespread Indo-Pacific taxa. These patterns are consistent with sites further offshore being more frequently exposed to the tropical East Australian Current (EAC). Patterns on reefs further inshore are consistent with the high levels of endemism previously reported for temperate and subtropical Australian waters. The complex cross-shelf arrangement of tropical, subtropical and temperate species results in high regional biodiversity and needs to be recognised in marine-park planning