ABSTRACT
Coral reefs are one of the most valuable yet threatened ecosystems in the world. Improving human wastewater treatment could reduce land-based impacts on coral reefs. However, information on the quantity and spatial distribution of human wastewater pollution is lacking. Here, we develop a spatial model linking residential human wastewater pollution (nitrogen and phosphorus/year) and conservation sectors [coral reefs] to better understand the relative differences in the distribution and efficacy of different sanitation services and their potential implications for conservation monitoring and management. We apply our model to Fiji, where ongoing initiatives and investments in wastewater treatment for human health could be leveraged to cost-effectively improve coral reef condition. We estimate that wastewater treatment plants account for nearly 80% of human wastewater nutrients released into surface waters. Wasterwater nutrient pollution is widespread, affecting 95% of reefs, but is concentrated across a few watersheds. Our spatially explicit approach can be used to better understand potential benefits and trade-offs between sanitation service improvements and coral reef health, helping to bridge the sanitation and conservation sectors as well as inform and prioritize on the ground action.
Subject(s)
Anthozoa , Coral Reefs , Humans , Animals , Ecosystem , Wastewater , Sanitation , Conservation of Natural ResourcesABSTRACT
Identifying locations of refugia from the thermal stresses of climate change for coral reefs and better managing them is one of the key recommendations for climate change adaptation. We review and summarize approximately 30 years of applied research focused on identifying climate refugia to prioritize the conservation actions for coral reefs under rapid climate change. We found that currently proposed climate refugia and the locations predicted to avoid future coral losses are highly reliant on excess heat metrics, such as degree heating weeks. However, many existing alternative environmental, ecological, and life-history variables could be used to identify other types of refugia that lead to the desired diversified portfolio for coral reef conservation. To improve conservation priorities for coral reefs, there is a need to evaluate and validate the predictions of climate refugia with long-term field data on coral abundance, diversity, and functioning. There is also the need to identify and safeguard locations displaying resistance toprolonged exposure to heat waves and the ability to recover quickly after thermal exposure. We recommend using more metrics to identify a portfolio of potential refugia sites for coral reefs that can avoid, resist, and recover from exposure to high ocean temperatures and the consequences of climate change, thereby shifting past efforts focused on avoidance to a diversified risk-spreading portfolio that can be used to improve strategic coral reef conservation in a rapidly warming climate.
Diversificación de los tipos de refugio necesarios para asegurar el futuro de los arrecifes de coral sujetos al cambio climático Resumen Una de las principales recomendaciones para la adaptación al cambio climático es identificar los refugios de los arrecifes de coral frente al estrés térmico del cambio climático y mejorar su gestión. Revisamos y resumimos â¼30 años de investigación aplicada centrada en la identificación de refugios climáticos para priorizar las acciones de conservación de los arrecifes de coral bajo un rápido cambio climático. Descubrimos que los refugios climáticos propuestos actualmente y las ubicaciones que pueden evitarlos dependen en gran medida de métricas de exceso de calor, como las semanas de calentamiento en grados (SCG). Sin embargo, existen muchas variables alternativas de historia vital, ambientales y ecológicas que podrían utilizarse para identificar otros tipos de refugios que resulten en el acervo diversificado que se desea para la conservación de los arrecifes de coral. Para mejorar las prioridades de conservación de los arrecifes de coral, es necesario evaluar y validar las predicciones sobre refugios climáticos con datos de campo a largo plazo sobre abundancia, diversidad y funcionamiento de los corales. También es necesario identificar y salvaguardar lugares que muestren resistencia a la exposición climática prolongada a olas de calor y la capacidad de recuperarse rápidamente tras la exposición térmica. Recomendamos utilizar más métricas para identificar un acervo de posibles lugares de refugio para los arrecifes de coral que puedan evitar, resistir y recuperarse de la exposición a las altas temperaturas oceánicas y las consecuencias del cambio climático, para así desplazar los esfuerzos pasados centrados en la evitación hacia un acervo diversificado de riesgos que pueda utilizarse para mejorar la conservación estratégica de los arrecifes de coral en un clima que se calienta rápidamente.
Subject(s)
Anthozoa , Coral Reefs , Animals , Ecosystem , Refugium , Climate Change , Conservation of Natural ResourcesABSTRACT
Management of the land-sea interface is essential for global conservation and sustainability objectives because coastal regions maintain natural processes that support biodiversity and the livelihood of billions of people. However, assessments of coastal regions have focused strictly on either the terrestrial or marine realm. Consequently, understanding of the overall state of Earth's coastal regions is poor. We integrated the terrestrial human footprint and marine cumulative human impact maps in a global assessment of the anthropogenic pressures affecting coastal regions. Of coastal regions globally, 15.5% had low anthropogenic pressure, mostly in Canada, Russia, and Greenland. Conversely, 47.9% of coastal regions were heavily affected by humanity, and in most countries (84.1%) >50% of their coastal regions were degraded. Nearly half (43.3%) of protected areas across coastal regions were exposed to high human pressures. To meet global sustainability objectives, all nations must undertake greater actions to preserve and restore the coastal regions within their borders.
costa, huella humana, impacto humano cumulativo, litoral, presión humana, restauración, tierras vírgenes Resumen El manejo de la interfaz entre la tierra y el mar es esencial para los objetivos mundiales de conservación y sustentabilidad ya que las regiones costeras mantienen los procesos naturales que sostienen a la biodiversidad y al sustento de miles de millones de personas. Sin embargo, los análisis de las regiones costeras se han enfocado estrictamente en el ámbito marino o en el terrestre, pero no en ambos. Por consiguiente, el conocimiento del estado general de las regiones costeras del planeta es muy pobre. Integramos la huella terrestre humana y mapas marinos del impacto humano cumulativo en un análisis global de las presiones antropogénicas que afectan las áreas costeras. De las áreas costeras de todo el mundo, el 15.5% tuvieron una presión antropogénica reducida, principalmente en Canadá, Rusia y Groenlandia. En cambio, el 47.9% de las regiones costeras estuvieron fuertemente afectas por la humanidad, y en la mayoría de los países (84.1%) >50% de sus regiones litorales se encuentran degradadas. Casi la mitad (43.3%) de las áreas protegidas en las regiones costeras tienen un grado de exposición a fuertes presiones humanas. Para cumplir los objetivos mundiales de sustentabilidad, todos los países deben emprender mejores acciones para preservar y restaurar las regiones litorales dentro de sus fronteras.
Subject(s)
Biodiversity , Conservation of Natural Resources , Canada , EcosystemSubject(s)
Biodiversity , Conservation of Natural Resources , Agriculture , Ecology , Fisheries , Humans , Indigenous Peoples , InternationalityABSTRACT
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
ABSTRACT
Humanity will soon define a new era for nature-one that seeks to transform decades of underwhelming responses to the global biodiversity crisis. Area-based conservation efforts, which include both protected areas and other effective area-based conservation measures, are likely to extend and diversify. However, persistent shortfalls in ecological representation and management effectiveness diminish the potential role of area-based conservation in stemming biodiversity loss. Here we show how the expansion of protected areas by national governments since 2010 has had limited success in increasing the coverage across different elements of biodiversity (ecoregions, 12,056 threatened species, 'Key Biodiversity Areas' and wilderness areas) and ecosystem services (productive fisheries, and carbon services on land and sea). To be more successful after 2020, area-based conservation must contribute more effectively to meeting global biodiversity goals-ranging from preventing extinctions to retaining the most-intact ecosystems-and must better collaborate with the many Indigenous peoples, community groups and private initiatives that are central to the successful conservation of biodiversity. The long-term success of area-based conservation requires parties to the Convention on Biological Diversity to secure adequate financing, plan for climate change and make biodiversity conservation a far stronger part of land, water and sea management policies.
Subject(s)
Conservation of Natural Resources/trends , Geographic Mapping , Animals , Aquatic Organisms , Biodiversity , Conservation of Natural Resources/economics , Conservation of Natural Resources/statistics & numerical data , Ecology/statistics & numerical data , Ecology/trends , History, 21st Century , WildernessABSTRACT
Seafood is one of the leading imported products implicated in foodborne outbreaks worldwide. Coastal marine environments are being increasingly subjected to reduced water quality from urbanization and leading to contamination of important fishery species. Given the importance of seafood exchanged as a global protein source, it is imperative to maintain seafood safety worldwide. To illustrate the potential health risks associated with urbanization in a coastal environment, we use next-generation high-throughput amplicon sequencing of the 16S ribosomal RNA gene combined with infrared spectroscopy to characterize and quantify a vast range of potential human bacterial pathogens and microdebris contaminants in seawater, sediment and an important oyster fishery along the Mergui Archipelago in Myanmar. Through the quantification of >1.25 million high-quality bacterial operational taxonomic unit (OTU) reads, we detected 5459 potential human bacterial pathogens belonging to 87 species that are commonly associated with gut microbiota and an indication of terrestrial runoff of human and agricultural waste. Oyster tissues contained 51% of all sequenced bacterial pathogens that are considered to be both detrimental and of emerging concern to human health. Using infrared spectroscopy, we examined a total of 1225 individual microdebris particles, from which we detected 78 different types of contaminant materials. The predominant microdebris contaminants recovered from oyster tissues included polymers (48%), followed by non-native minerals (20%), oils (14%) and milk supplement powders (14%). Emerging technologies provide novel insights into the impacts of coastal development on food security and risks to human and environmental health.
Subject(s)
Environmental Monitoring , Urbanization , Animals , Food Contamination/analysis , Humans , Myanmar , Seafood , SeawaterABSTRACT
Climate change is shifting the ranges of species. Simple predictive metrics of range shifts such as climate velocity, that do not require extensive knowledge or data on individual species, could help to guide conservation. We review research on climate velocity, describing the theory underpinning the concept and its assumptions. We highlight how climate velocity has already been applied in conservation-related research, including climate residence time, climate refugia, endemism, historic and projected range shifts, exposure to climate change, and climate connectivity. Finally, we discuss ways to enhance the use of climate velocity in conservation through tailoring it to be more biologically meaningful, informing design of protected areas, conserving ocean biodiversity in 3D, and informing conservation actions.
Subject(s)
Biodiversity , Climate Change , Conservation of Natural Resources , Global Warming , Oceans and SeasABSTRACT
Optically active water quality components (OAC) transported by flood plumes to nearshore marine environments affect light levels. The definition of minimum OAC concentrations that must be maintained to sustain sufficient light levels for conservation of light-dependant coastal ecosystems exposed to flood waters is necessary to guide management actions in adjacent catchments. In this study, a framework for defining OAC target concentrations using empirical light attenuation models is proposed and applied to the Wet Tropics region of the Great Barrier Reef (GBR) (Queensland, Australia). This framework comprises several steps: (i) light attenuation (Kd(PAR)) profiles and OAC measurements, including coloured dissolved organic matter (CDOM), chlorophyll-a (Chl-a) and suspended particulate matter (SPM) concentrations collected in flood waters; (ii) empirical light attenuation models used to define the contribution of CDOM, Chl-a and SPM to the light attenuation, and; (iii) translation of empirical models into manageable OAC target concentrations specific for wet season conditions. Results showed that (i) Kd(PAR) variability in the Wet Tropics flood waters is driven primarily by SPM and CDOM, with a lower contribution from Chl-a (r2â¯=â¯0.5, pâ¯<â¯0.01), (ii) the relative contributions of each OAC varies across the different water bodies existing along flood waters and strongest Kd(PAR) predictions were achieved when the in-situ data were clustered into water bodies with similar satellite-derived colour characteristics ('brownish flood waters', r2â¯=â¯0.8, pâ¯<â¯0.01, 'greenish flood waters', r2â¯=â¯0.5, pâ¯<â¯0.01), and (iii) that Kd(PAR) simulations are sensitive to the angular distribution of the light field in the clearest flood water bodies. Empirical models developed were used to translate regional light guidelines (established for the GBR) into manageable OAC target concentrations. Preliminary results suggested that a 90th percentile SPM concentration of 11.4â¯mgâ¯L-1 should be maintained during the wet season to sustain favourable light levels for Wet Tropics coral reefs and seagrass ecosystems exposed to 'brownish' flood waters. Additional data will be collected to validate the light attenuation models and the wet season target concentration which in future will be incorporated into wider catchment modelling efforts to improve coastal water quality in the Wet Tropics and the GBR.
Subject(s)
Coral Reefs , Ecosystem , Water Quality , Australia , Environmental Monitoring , Queensland , SeasonsABSTRACT
Reduced water quality, in particular increases in suspended sediments, has been linked to declines in fish abundance on coral reefs. Changes in gill structure induced by suspended sediments have been hypothesized to impair gill function and may provide a mechanistic basis for the observed declines; yet, evidence for this is lacking. We exposed juveniles of three reef fish species (Amphiprion melanopus, Amphiprion percula and Acanthochromis polyacanthus) to suspended sediments (0-180 mg l-1) for 7 days and examined changes in gill structure and metabolic performance (i.e. oxygen consumption). Exposure to suspended sediments led to shorter gill lamellae in A. melanopus and A. polyacanthus and reduced oxygen diffusion distances in all three species. While A. melanopus exhibited impaired oxygen uptake after suspended sediment exposure, i.e. decreased maximum and increased resting oxygen consumption rates resulting in decreased aerobic scope, the oxygen consumption rates of the other two species remained unaffected. These findings imply that species sensitive to changes in gill structure such as A. melanopus may decline in abundance as reefs become more turbid, whereas species that are able to maintain metabolic performance despite suspended sediment exposure, such as A. polyacanthus or A. percula, may be able to persist or gain a competitive advantage.
Subject(s)
Coral Reefs , Geologic Sediments/analysis , Gills/physiopathology , Perciformes/metabolism , Animals , Environmental Monitoring , Random Allocation , Species SpecificityABSTRACT
Coastal ecosystems can be degraded by poor water quality. Tracing the causes of poor water quality back to land-use change is necessary to target catchment management for coastal zone management. However, existing models for tracing the sources of pollution require extensive data-sets which are not available for many of the world's coral reef regions that may have severe water quality issues. Here we develop a hierarchical Bayesian model that uses freely available satellite data to infer the connection between land-uses in catchments and water clarity in coastal oceans. We apply the model to estimate the influence of land-use change on water clarity in Fiji. We tested the model's predictions against underwater surveys, finding that predictions of poor water quality are consistent with observations of high siltation and low coverage of sediment-sensitive coral genera. The model thus provides a means to link land-use change to declines in coastal water quality.
Subject(s)
Anthozoa/growth & development , Conservation of Natural Resources/methods , Environmental Monitoring/methods , Water Quality , Animals , Bayes Theorem , Coral Reefs , Ecosystem , Fiji , Oceans and Seas , Satellite Imagery/statistics & numerical dataABSTRACT
Around the globe, islands are the last refuge for many threatened and endemic species. Islands are frequently also important sites for recreation, cultural activities, and industrial development, all of which facilitate the establishment of invasive species. Surveillance is employed on islands to detect the establishment of invasive species after their arrival, leading to decisions about follow-up actions. Unless surveillance is prioritised according to risk of establishment of invasives, it may be infeasible to implement efficiently over large tracts of publicly accessible land, especially in data-deficient areas. The key biosecurity problem for many regions is one of prioritizing sites for surveillance activities and identifying invasive species most likely to disperse to, and establish, and proliferate on those sites. We created a series of Bayesian Belief Networks (BBNs), linked by Java computing code and the freely available GeNIe application to automate the creation and computation of species- and site-specific biosecurity BBNs. The BBNs require data on island attributes, recreational or industrial visitor load, infrastructure, habitat availability, and animal behaviour and dispersal via swimming, flying, human movement, land bridges, or flood plumes. We used this biosecurity BBN to estimate the risk of 11 invasive faunal species arriving and establishing on 600 islands along the Pilbara coastline, Western Australia. Sensitivity analyses were conducted to identify nodes within the BBNs that required refined data inputs. Propagule pressure was the node with the greatest influence over the number of arrivals. Other nodes such as the number of visitors to islands and swimming capabilities of invasive animals greatly influenced the model results. Across the 11 species studied, our models predicted one arrival per 300 visitors. The biosecurity BBN can be used to identify the islands at highest risk from establishment of invasive species within any archipelago/s, and the invasive species most likely to establish on each island.
Subject(s)
Bayes Theorem , Conservation of Natural Resources/methods , Introduced Species , Islands , Animals , Australia , RiskABSTRACT
Coral reefs are increasingly subjected to both local and global stressors, however, there is limited information on how reef organisms respond to their combined effects under natural conditions. This field study examined the growth response of the damselfish Neopomacentrus bankieri to the individual and combined effects of multiple abiotic factors. Turbidity, temperature, tidal movement, and wave action were recorded every 10 minutes for four months, after which the daily otolith growth of N. bankieri was aligned with corresponding abiotic conditions. Temperature was the only significant driver of daily otolith increment width, with increasing temperatures resulting in decreasing width. Although tidal movement was not a significant driver of increment width by itself, the combined effect of tidal movement and temperature had a greater negative effect on growth than temperature alone. Our results indicate that temperature can drive changes in growth even at very fine scales, and demonstrate that the cumulative impact of abiotic factors can be substantially greater than individual effects. As abiotic factors continue to change in intensity and duration, the combined impacts of them will become increasingly important drivers of physiological and ecological change.
Subject(s)
Anthozoa/physiology , Coral Reefs , Ecosystem , Fishes/physiology , Otolithic Membrane/growth & development , Animals , Australia , Conservation of Natural Resources/methods , Geography , Models, Theoretical , Seasons , Temperature , Tidal Waves , Time FactorsABSTRACT
Marine protected areas can prevent over-exploitation, but their effect on marine diseases is less clear. We examined how marine reserves can reduce diseases affecting reef-building corals following acute and chronic disturbances. One year after a severe tropical cyclone, corals inside reserves had sevenfold lower levels of disease than those in non-reserves. Similarly, disease prevalence was threefold lower on reserve reefs following chronic exposure to terrestrial run-off from a degraded river catchment, when exposure duration was below the long-term site average. Examination of 35 predictor variables indicated that lower levels of derelict fishing line and injured corals inside reserves were correlated with lower levels of coral disease in both case studies, signifying that successful disease mitigation occurs when activities that damage reefs are restricted. Conversely, reserves were ineffective in moderating disease when sites were exposed to higher than average levels of run-off, demonstrating that reductions in water quality undermine resilience afforded by reserve protection. In addition to implementing protected areas, we highlight that disease management efforts should also target improving water quality and limiting anthropogenic activities that cause injury.
Subject(s)
Anthozoa/microbiology , Conservation of Natural Resources/methods , Animals , Coral Reefs , Host-Pathogen InteractionsABSTRACT
Near-shore marine environments are increasingly subjected to reduced water quality, and their ability to withstand it is critical to their persistence. The potential role marine reserves may play in mitigating the effects of reduced water quality has received little attention. We investigated the spatial and temporal variability in live coral and macro-algal cover and water quality during moderate and major flooding events of the Fitzroy River within the Keppel Bay region of the Great Barrier Reef Marine Park from 2007 to 2013. We used 7 years of remote sensing data on water quality and data from long-term monitoring of coral reefs to quantify exposure of coral reefs to flood plumes. We used a distance linear model to partition the contribution of abiotic and biotic factors, including zoning, as drivers of the observed changes in coral and macro-algae cover. Moderate flood plumes from 2007 to 2009 did not affect coral cover on reefs in the Keppel Islands, suggesting the reef has intrinsic resistance against short-term exposure to reduced water quality. However, from 2009 to 2013, live coral cover declined by â¼ 50% following several weeks of exposure to turbid, low salinity water from major flood plume events in 2011 and subsequent moderate events in 2012 and 2013. Although the flooding events in 2012 and 2013 were smaller than the flooding events between 2007 to 2009, the ability of the reefs to withstand these moderate floods was lost, as evidenced by a â¼ 20% decline in coral cover between 2011 to 2013. Although zoning (no-take reserve or fished) was identified a significant driver of coral cover, we recorded consistently lower coral cover on reserve reefs than on fished reefs throughout the study period and significantly lower cover in 2011. Our findings suggest that even reefs with an inherent resistance to reduced water quality are not able to withstand repeated disturbance events. The limitations of reserves in mitigating the effects of reduced water quality on near-shore coral reefs underscores the importance of integrated management approaches that combine effective land-based management with networks of no-take reserves.
Subject(s)
Conservation of Natural Resources , Coral Reefs , Water Quality , Animal Distribution , Animals , Anthozoa/physiology , Floods , Queensland , Seaweed/physiologyABSTRACT
Worldwide, increasing coastal development has played a major role in shaping coral reef species assemblages, but the mechanisms underpinning distribution patterns remain poorly understood. Recent research demonstrated delayed development in larval fishes exposed to suspended sediment, highlighting the need to further understand the interaction between suspended sediment as a stressor and energetically costly activities such as growth and development that are essential to support biological fitness. We examined the gill morphology and the gill microbiome in clownfish larvae (Amphiprion percula) exposed to suspended sediment concentrations (using Australian bentonite) commonly found on the inshore Great Barrier Reef. The gills of larvae exposed to 45 mg L(-1) of suspended sediment had excessive mucous discharge and growth of protective cell layers, resulting in a 56% thicker gill epithelium compared to fish from the control group. Further, we found a shift from 'healthy' to pathogenic bacterial communities on the gills, which could increase the disease susceptibility of larvae. The impact of suspended sediments on larval gills may represent an underlying mechanism behind the distribution patterns of fish assemblages. Our findings underscore the necessity for future coastal development to consider adverse effects of suspended sediments on fish recruitment, and consequently fish populations and ecosystem health.
Subject(s)
Coral Reefs , Fishes , Geologic Sediments , Animals , Fishes/anatomy & histology , Fishes/microbiology , Gills/anatomy & histology , Gills/microbiology , Larva , MicrobiotaABSTRACT
River plumes are the major transport mechanism for nutrients, sediments and other land-based pollutants into the Great Barrier Reef (GBR, Australia) and are a major threat to coastal and marine ecosystems such as coral reefs and seagrass beds. Understanding the spatial extent, frequency of occurrence, loads and ecological impacts of land-based pollutants discharged through river plumes is essential to drive catchment management actions. In this study, a framework to produce river plume risk maps for seagrass and coral ecosystems, using supervised classification of MODIS Level 2 (L2) satellite products, is presented. Based on relevant L2 thresholds, river plumes are classified into Primary, Secondary, and Tertiary water types, which represent distinct water quality (WQ) parameters concentrations and combinations. Annual water type maps are produced over three wet seasons (2010-2013) as a case of study. These maps provide a synoptic basis to assess the likelihood and magnitude of the risk of reduced coastal WQ associated with the river discharge (river plume risk) and in combination with sound knowledge of the regional ecosystems can serve as the basis to assess potential ecological impacts for coastal and marine GBR ecosystems. The methods described herein provide relevant and easily reproducible large-scale information for river plume risk assessment and management.
Subject(s)
Coral Reefs , Rivers , Satellite Imagery , Animals , Anthozoa , Australia , Ecosystem , Magnoliopsida , Risk , Water , Water Pollutants, Chemical , Water QualityABSTRACT
Increasing sediment input into coastal environments is having a profound influence on shallow marine habitats and associated species. Coral reef ecosystems appear to be particularly sensitive, with increased sediment deposition and re-suspension being associated with declines in the abundance and diversity of coral reef fishes. While recent research has demonstrated that suspended sediment can have negative impacts on post-settlement coral reef fishes, its effect on larval development has not been investigated. In this study, we tested the effects of different levels of suspended sediment on larval growth and development time in Amphiprion percula, a coral reef damselfish. Larvae were subjected to four experimental concentrations of suspended sediment spanning the range found around coastal coral reefs (0-45 mg l(-1)). Larval duration was significantly longer in all sediment treatments (12 days) compared with the average larval duration in the control treatment (11 days). Approximately 75% of the fish in the control had settled by day 11, compared with only 40-46% among the sediment treatments. In the highest sediment treatment, some individuals had a larval duration twice that of the median duration in the control treatment. Unexpectedly, in the low sediment treatment, fish at settlement were significantly longer and heavier compared with fish in the other treatments, suggesting delayed development was independent of individual condition. A sediment-induced extension of the pelagic larval stage could significantly reduce numbers of larvae competent to settle and, in turn, have major effects on adult population dynamics.
Subject(s)
Perciformes/growth & development , Water Pollutants/adverse effects , Age Distribution , Animals , Bentonite , Coral Reefs , Female , Geologic Sediments , Larva/growth & development , Male , Metamorphosis, BiologicalABSTRACT
The otx2 gene encodes a transcription factor (OTX2) essential in the formation of the brain and sensory systems. Specifically, OTX2-positive cells are associated with axons in the olfactory system of mice and otx2 is upregulated in odour-exposed zebrafish, indicating a possible role in olfactory imprinting. In this study, otx2 was used as a candidate gene to investigate the molecular mechanisms of olfactory imprinting to settlement cues in the coral reef anemonefish, Amphiprion percula. The A. percula otx2 (Ap-otx2) gene was elucidated, validated, and its expression tested in settlement-stage A. percula by exposing them to behaviourally relevant olfactory settlement cues in the first 24â hours post-hatching, or daily throughout the larval phase. In-situ hybridisation revealed expression of Ap-otx2 throughout the olfactory epithelium with increased transcript staining in odour-exposed settlement-stage larval fish compared to no-odour controls, in all scenarios. This suggests that Ap-otx2 may be involved in olfactory imprinting to behaviourally relevant settlement odours in A. percula.
ABSTRACT
Increased loads of land-based pollutants are a major threat to coastal-marine ecosystems. Identifying the affected marine areas and the scale of influence on ecosystems is critical to assess the impacts of degraded water quality and to inform planning for catchment management and marine conservation. Studies using remotely-sensed data have contributed to our understanding of the occurrence and influence of river plumes, and to our ability to assess exposure of marine ecosystems to land-based pollutants. However, refinement of plume modeling techniques is required to improve risk assessments. We developed a novel, complementary, approach to model exposure of coastal-marine ecosystems to land-based pollutants. We used supervised classification of MODIS-Aqua true-color satellite imagery to map the extent of plumes and to qualitatively assess the dispersal of pollutants in plumes. We used the Great Barrier Reef (GBR), the world's largest coral reef system, to test our approach. We combined frequency of plume occurrence with spatially distributed loads (based on a cost-distance function) to create maps of exposure to suspended sediment and dissolved inorganic nitrogen. We then compared annual exposure maps (2007-2011) to assess inter-annual variability in the exposure of coral reefs and seagrass beds to these pollutants. We found this method useful to map plumes and qualitatively assess exposure to land-based pollutants. We observed inter-annual variation in exposure of ecosystems to pollutants in the GBR, stressing the need to incorporate a temporal component into plume exposure/risk models. Our study contributes to our understanding of plume spatial-temporal dynamics of the GBR and offers a method that can also be applied to monitor exposure of coastal-marine ecosystems to plumes and explore their ecological influences.