The Tamar Estuary and Esk Rivers (TEER) program is a collaboration of stakeholders that provide a coordinated approach to manage and guide investment to protect, maintain and enhance the Tamar Estuary and Esk Rivers. The aims of the program include protecting, restoring and enhancing the waterway through a variety of initiatives. The Ecosystem Health Assessment Program is one such initiative that monitors water quality in the Tamar estuary and uses this information for evaluating management strategies. The main outcome of the monitoring is a report card that was released every two years prior to 2017 and every year from 2018, giving each of the five zones of the Tamar estuary a grade. The EHAP program has 10 years of data which has not previously been looked at as a single dataset. Monthly water quality data that includes biotic (e.g. enterococcus), abiotic (e.g. suspended solids, nitrogen and ammonia) and metals (e.g. aluminium and zinc) have been collected from the surface waters. This kind of consistent time series data can be very useful for looking at changes over time especially in relation to climate change, changes in the use of the estuary and natural long-term variability. In celebration of the 10 years of TEER, this presentation will provide an overview of some of the changes seen over the 10 years of monitoring and how they may relate to changes in the Tamar estuary.

The Great Barrier Reef (GBR) is an iconic ecosystem that supports hundreds of thousands of seabirds that breed on offshore islands and cays. Despite evidence of localised declines of some species as early as the mid-1990’s, Reef-wide trends in seabird populations have never been quantified. We estimated site-specific and Reef-wide trends for six common and widespread species (crested tern, brown booby, masked booby, common noddy, sooty tern, roseate tern) and a single island trend for red-tailed tropicbird, from 38 years of monitoring data collected by the Queensland Parks & Wildlife Service using a model that accounted for spatiotemporal variability in monitoring effort as well as seasonal variation in breeding phenology. Reef-wide trends indicated probable declines in all six multi-site species, ranging from a mean estimate of -0.73% to -1.95% per year with probabilities of decline ranging from 0.74 to 0.93. Brown booby showed the highest rates and most widespread evidence of decline. However, both booby species also showed increases at some sites. Site-specific trends for terns and common noddy were generally stable, but with the exception of crested terns (Michaelmas Cay) and red-tailed tropicbirds (Raine Island), there was no evidence for site-specific increases in these taxa. The consistent negative direction of Reef-wide trends across six species that differ to varying degrees in their life history, foraging strategies, and year-round distributions reinforces concerns raised by earlier studies about the trajectory of the GBR’s seabird populations. Causes of these declines need to be identified and priority assigned to Reef-wide recovery actions.

Protected areas are central to biodiversity conservation. For marine fish, Marine Protected Areas (MPAs) often harbour more individuals, especially of species targeted by fisheries. But how local-scale responses combine to affect regional biodiversity, a management concern for spatial networks of MPAs, remains largely unknown. Using standardised underwater visual survey data from 43 MPAs and 41 fished areas in the Mediterranean Sea, we quantified how species richness changed inside MPAs as a function of spatial scale. At both local and regional scales, increased species evenness caused by increased numbers of common species was the most important proximate driver of higher diversity in MPAs. Site-to-site variation in the composition of common exploited species was also higher among protected sites. Although MPAs are known to influence fish community abundance and biomass, we found changes to the relative abundance of species dominated the biodiversity response to protection. MPAs had more relatively common species, which in turn led to higher diversity for a given sampling effort. Moreover, greater site-to-site variation in numbers of common exploited species meant that local scale responses inside MPAs were magnified at the regional scale. Quantifying how multiple components of biodiversity respond across spatial scales will strengthen regional conservation efforts.

The pressures of global climate change and ocean warming are degrading coral reef ecosystems worldwide, and active management of reef coral populations through restoration techniques has increased in response. A major consideration in reef restoration has been the strategic selection of coral species for ecological resilience. Recent research on Australia’s Great Barrier Reef (GBR) has identified that corals exposed to sub-lethal temperature conditions preceding bleaching events may acquire increased stress tolerance. Here we present an experimental approach towards investigating the thermal tolerance of Pocillopora damicornis, a scleractinian coral species that is a target of restoration practices due to its success as an environmental generalist. The present study exposed 18 colonies of P. damicornis to two historical summertime sea surface temperature (SST) trajectories recorded on the GBR: protective, in which a sub-bleaching temperature pulse (32°C) precedes bleaching conditions (34°C); and single, where temperatures gradually increase to the bleaching threshold (34°C). To address the hypothesis that P. damicornis colonies exposed to initial sub-lethal temperatures can acquire tolerance to thermal stress, we measured photo-physiological parameters, densities of endosymbionts, and microbial community shifts. While both single (heatwave conditions) and protective heating trajectories (predominant conditions prior to marine heatwave emergence) corresponded with a decline in photosystem performance and symbiont densities in coral colonies, results indicate that thermal tolerance cannot be attributed to endosymbionts alone. A holistic view of the interactions between the coral host, symbiont species, and microbial communities that compose the coral holobiont must be taken to ultimately determine bleaching response of P. damicornis.

Coral cays provide important human services and serve as a habitat for a variety of terrestrial, amphibious, and marine fauna. Normally, the precipitation of calcium carbonate by calcifying coral reef organisms leads to the long-term accumulation of sedimentary carbonates within coral reef lagoons, a process which is critical to the formation and subsistence of these coral cays. However, climate change is causing a decline in coral calcification, increase in carbonate sediment dissolution, and a rise in sea level that, collectively, has already begun washing away these low-lying tropical islands. Here we show how coral reef sediments will shift from a state of net accumulation to a state of net dissolution in response to three anthropogenic stressors: (1) ocean acidification (OA), (2) global warming and (3) coastal eutrophication. OA will enhance sediment dissolution geochemically via a reduction in seawater pH and subsequent undersaturation of carbonate mineral phases (Ω). Warming and eutrophication will enhance carbonate dissolution biologically via a shift in organic matter remineralization processes, transitioning the collective microbenthic metabolism from a present state of net autotrophy (sink for CO2) to net heterotrophy (source of CO2). This shift will also lower seawater pH and Ω, further accelerating overall rates of net sediment dissolution. When considered in the context of sea level rise and the projected reduction in calcification rates by reef organisms, many coral cays worldwide could wash away before the year 2100, requiring geoengineering and restorative solutions to counteract the loss of carbonate sediments and inundation of low-lying tropical islands.

Coral reefs make up a mere one percent of our ocean, yet they contain 25% of all marine life. This resource not only supports rich marine biodiversity but also provides numerous ecological goods and services. Predicted climate trajectories threaten the existence of this entire ecosystem through anthropogenic perturbations, in particular coral bleaching. Coral bleaching is one of the most significant threats to coral reef health and coral community structure. The World Heritage Site, Lord Howe Island is a unique site exposed to subtropical and temperate waters with high levels of endemism. As a consequence of current climate regimes Lord Howe Island experienced their third coral bleaching event this year since 1998. Some sites within the lagoon showed up to 92 % of coral colonies impacted by bleaching with some coral species, such as Acropora sp. showing no signs of bleaching whilst 73.6 % of Stylophora pistillata colonieswere impacted by the bleaching event. Given coral bleaching events are set to rise in their spatial distribution as well as their intensity it is crucial to identify site variability and species resilience at given reefs as an indicator for the future status of coral reef sites.
This study aims at assisting reef managers to establish a holistic understanding of the 2019 bleaching event at Lord Howe Island by monitoring both ecological impacts of bleaching and the microbial and symbiont abundance and diversity of healthy and bleached corals.

All scales of life experience disturbances and then are required to recover to a healthy state to survive. However, a recovered healthy state is hard to define in today’s changing climate. For example, under increasing sea surface temperatures, marine ecosystems may not return to a pre-disturbed state after disturbance. Therefore, the questions arise how do we define recovery under climate change scenarios? And how do we understand the health of an ecosystem after a disturbance such as coral bleaching? Bleached corals have the potential to regain their algal symbionts once sea surface temperatures drop into the normal thermal range. However, regaining symbionts does not necessarily mean that the meta-symbiotic organism has recovered, or that the ecological function (s) provided has returned. Recovery after bleaching is much more than just regaining symbionts. Terms that are widely used in studying ecosystem recovery have not yet been considered in the context of coral bleaching. Terms such as climax community, stable states, and disturbance need to be specified in coral reef systems to understand and categorize states of coral, and reef recovery. Here we aim to characterize the specific stages of coral recovery following bleaching, from re-establishment of symbiosis to returned ecological role. By re-defining these terms in the coral reef system and by studying the process of recovery after bleaching, we can better assess coral reef health and management strategies to mitigate bleaching. To accurately assess the health of corals, we need to be operating on correct and current definitions of recovery.