Threats to biodiversity in Australia’s Burdekin River Basin

[Extract] The Murray-Darling basin in Australia (Figure 1) is a prime example of a whole river basin suffering from environmental degradation from historical, haphazard developments without integrated planning [1]. A similar scenario is developing for the Burdekin River basin in North Queensland. The average flow of the Burdekin River is over 40% that of the Murray-Darling. The only existing large dam on the river is the Burdekin Falls Dam, constructed in 1987; it traps 88% of the watershed. It provides irrigation water for irrigated sugar farms in the lower Burdekin. For the environment and biodiversity, the key issues from dams are the impact on the river, the coast, and the Great Barrier Reef of the dams interfering with the sediment loads and the runoff from fertilized irrigated farms. There are currently business case studies for raising by 2m the Burdekin Falls Dam, and for three new dams (Figure 1): Hells Gates Dam, Urannah Dam, and the Big Rocks Weir. The Hells Gates and the Urannah dams would double the existing extraction of water for irrigation

Damming the Mekong and Ord River estuaries

Cambridge Gulf, tropical Western Australia, is a macro-tidal estuary with 8 m tides. The West arm is largely untouched by human activities. The East arm is the estuary of the Ord River affected by two river dams constructed 30 years ago. The West arm appears to be at equilibrium since there has been no net loss or gain of sediment for the last 111 years. Tidal dynamics and occasional river floods appear responsible for self-scouring this channel. The East arm has measurably silted the last 30 years, the stream cross-sectional area being halved. Field and numerical studies suggest that this is due to the dam-induced suppression of large river floods, this has increased tidal pumping of sediment. The Ord River estuary is now geomorphologically unstable. Can this also occur in the Mekong delta? The estuary is shallow with a mean maximum tidal range of 3.2 m. The freshwater discharge varies seasonally between 40,000 and 1,700m³s⁻¹. The delta is heavily populated with about 32 million people, mostly rice farmers and fishermen. The estuary is their main transport route, which is hindered by siltation at the mouth. Irrigation for rice is hindered by salinity intrusion and acid sulfate soils in the low flow season. A water-sediment dynamics model was applied to the Mekong River, calibrated against the (sparse) oceanographic data and used to predict qualitatively the effects of the 100 proposed dams and the water diversion schemes in the Mekong River catchment. The model predicts that the salinity intrusion in the estuary may increase for several months a year, coastal erosion may increase, siltation in the estuary may increase by up to 7 x 105 tonnes per year, and the wet-season flushing of acid sulfates will decrease. Detailed investigations are warranted

Estuarine ecohydrology

Throughout the world, estuaries and coastal waters have experienced environmental degradation. Present proposed remedial measures based on engineering and technological fix have been unable to restore the ecological processes of a healthy, robust estuary and, as such, will not reinstate the full beneficial functions of the estuary ecosystem

Oceanographic Processes of Coral Reefs: physical and biological links in the Great Barrier Reef

Demonstrating the relevance and need of science in planning the future of the Great Barrier Reef and coral reefs worldwide, Oceanographic Processes of Coral Reefs: Physical and Biological Links in the Great Barrier Reef emphasizes multi-disciplinary processes - physical and biological links - that have emerged as the dominant forces shaping and controlling the ecosystem. The book draws heavily on data from coral reefs in Australia, Indonesia, Thailand, and the Philippines

Tidal period upwelling within Raine Island Entrance Great Barrier Reef

Temperature and current measurements collected from November 1981 to May 1982 at the head of Raine Island Entrance reveal tidally-induced upwelling of cold continental slope water onto the continental shelf. Daily tidal motions account for approximately 80% of the total cross-shelf eddy heat flux of 0.79 ± 1.01 cal cm−2 s−1. Although temperature and current fluctuations are principally of semidiurnal period, the heat flux is principally at diurnal period. Based on empirical nutrient-temperature relations we estimate the onshore inorganic nutrient fluxes to be 0.9 (±1.2) × 10−2 mmol m−2 s−1 for nitrate, 0.6 (±0.8) × 10−2 mmol m−2 s−1 for silicate and 0.7 (±0.9) × 10−3 mmol m−2 s−1 for phosphate.The upwelling is explained in terms of fluid withdrawal-type mechanisms in which nutrient-rich thermocline water below 100 m depth is drawn onto the shallow (40 m) shelf during the flood. We suggest that this tidal period inundation of the outer reefs is an important mechanism for effectively upgrading nominally low nutrient levels. Reef growth is expected to be most prolific near the shelf break where the time-integrated contribution of the upwelling is greatest

The Role of Physical Processes in Mangrove Environments: manual for the preservation and utilization of mangrove ecosystems

Being a scientific society with a vested interest in the protection and restoration of mangroves and other coastal environments, it is with great pride that The International Society for Mangrove Ecosystems (ISME) provides the foreword to this important new work. In recognising the economic and ecological importance of mangrove forests and ecosystems, we have a responsibility to provide the means to sustainably manage and protect this vital coastal resource for future generations. Edited by three outstanding mangrove experts—Prof. Y. Mazda, Dr. E. Wolanski and Dr. P.V. Ridd—this book targets members of the scientific community who are interested in the preservation and sustainable utilisation of mangrove forests. The book has set itself five principal objectives: 1) To instruct mangrove researchers and engineers in developing countries on the physical processes taking place in the mangrove environment; 2) To encourage students to undertake studies of physical processes in mangrove areas; 3) To make coastal physical researchers recognise the peculiarity of mangrove physics; 4) To show the physical mechanisms that have been solved and need to be solved; and 5) To save research time by providing ready access to scientific articles and papers that appear in diverse media in different countries. As reliable information is fundamental to the long-term health of mangrove ecosystems, ISME believes that this book will provide and contribute to the strengthening of scientific understanding, as well as the development and exchange of essential data and information required for the conservation, restoration and management of mangrove forests. The information developed and provided in the book constitutes a vital new resource for effective decision-making and policy formulation in the sustainable management of all mangrove ecosystems

Ecoengineering with Ecohydrology: Successes and failures in estuarine restoration

© 2016 Elsevier Ltd. Ecological Engineering (or Ecoengineering) is increasingly used in estuaries to re-create and restore ecosystems degraded by human activities, including reduced water flow or land poldered for agricultural use. Here we focus on ecosystem recolonization by the biota and their functioning and we separate Type A Ecoengineering where the physico-chemical structure is modified on the basis that ecological structure and functioning will then follow, and Type B Ecoengineering where the biota are engineered directly such as through restocking or replanting. Modifying the physical system to create and restore natural processes and habitats relies on successfully applying Ecohydrology, where suitable physical conditions, especially hydrography and sedimentology, are created to recover estuarine ecology by natural or human-mediated colonisation of primary producers and consumers, or habitat creation. This successional process then allows wading birds and fish to reoccupy the rehabilitated areas, thus restoring the natural food web and recreating nursery areas for aquatic biota. We describe Ecohydrology principles applied during Ecoengineering restoration projects in Europe, Australia, Asia, South Africa and North America. These show some successful and sustainable approaches but also others that were less than successful and not sustainable despite the best of intentions (and which may even have harmed the ecology). Some schemes may be 'good for the ecologists', as conservationists consider it successful that at least some habitat was created, albeit in the short-term, but arguably did little for the overall ecology of the area in space or time. We indicate the trade-offs between the short- and long-term value of restored and created ecosystems, the success at developing natural structure and functioning in disturbed estuaries, the role of this in estuarine and wetland management, and the costs and benefits of Ecoengineering to the socio-ecological system. These global case studies provide important lessons for both the science and management of estuaries, including that successful estuarine restoration is a complex and often difficult process, and that Ecoengineering with Ecohydrology aims to control and/or simulate natural ecosystem processes

An ecohydrology model of the Guadiana Estuary (South Portugal)

A 1-D ecohydrology model is proposed that integrates physical, chemical and biological processes in the Guadiana Estuary during low flow conditions and that predicts the ecosystem health as determined by the following variables: river discharge, nutrients, suspended particulate matter, phytoplankton, zooplankton, bivalves, zooplanktivorous fish and carnivorous/omnivorous fish. Low flow conditions prevail now that the Alqueva dam has been constructed. The ecological sub-model is based on the non-linear Lotka-Volterra equation. The model is successful in capturing the observations of along-river changes in these variables. It suggests that both bottom-up and top-down ecological processes control the Guadiana Estuary ecosystem health. A number of sensitivity tests show that the model is robust and can be used to predict e within likely error bounds provided by the sensitivity tests e the consequences on the estuary ecosystem health of human activities throughout the river catchment, such as the irrigation farming downstream of the Alqueva dam, reclamation of the salt marshes by urban developments, and flow regulation by the Alqueva dam. The model suggests that the estuarine ecosystem health requires transient river floods and is compromised by flow regulation by the Alqueva dam. Remedial measures are thus necessary

Coasts and Estuaries: the future

Coasts and Estuaries: The Future provides valuable information on how we can protect and maintain natural ecological structures while also allowing estuaries to deliver services that produce societal goods and benefits. These issues are addressed through chapters detailing case studies from estuaries and coastal waters worldwide, presenting a full range of natural variability and human pressures. Following this, a series of chapters written by scientific leaders worldwide synthesizes the problems and offers solutions for specific issues graded within the framework of the socio-economic-environmental mosaic. These include fisheries, climate change, coastal megacities, evolving human-nature interactions, remediation measures, and integrated coastal management. The problems faced by half of the world living near coasts are truly a worldwide challenge as well as an opportunity for scientists to study commonalities and differences and provide solutions. This book is centered around the proposed DAPSI(W)R(M) framework, where drivers of basic human needs requires activities that each produce pressures. The pressures are mechanisms of state change on the natural system and Impacts on societal welfare (including well-being). These problems then require responses, which are the solutions relating to governance, socio-economic and cultural measures (Scharin et al 2016)

Behavioural and oceanographic isolation of an island‑based jellyfish (Copula sivickisi, Class Cubozoa) population

Cubozoan jellyfish are classified as plankton despite the strong swimming and orientation abilities of cubomedusae. How these capabilities could affect cubozoan population structures is poorly understood. Medusae of the cubozoan Copula sivickisi can uniquely attach to surfaces with the sticky pads on their bells. Biophysical modelling was used to investigate the spatial scales of connectivity in a C. sivickisi population. When the medusae were active at night they could maintain their observed distribution on fringing reef if they attached to the reef when the current speed exceeded a moderate threshold. This behaviour facilitated the isolation of a C. sivickisi population on reefs fringing Magnetic Island, Queensland, Australia. Within this distribution, there was considerable within bay retention and medusae rarely travelled > 3 km. The few (< 0.1%) medusae lost from the island habitat were largely advected into open water and away from the mainland coast which lies 8 km from the island. Given that successful emigration is unlikely, the island population probably represents a stock that is ecologically distinct from any mainland populations. The cosmopolitan distribution of C. sivickisi could contain incipient or cryptic species given the small scales of connectivity demonstrated here