Papers by Michael Rasheed
Port of Townsville Seagrass Monitoring Program: 2019
Long term ambient water quality monitoring to support port management in the Great Barrier Reef World Heritage Area
The condition of the Great Barrier Reef World Heritage Area (GBRWHA) is important to the Australi... more The condition of the Great Barrier Reef World Heritage Area (GBRWHA) is important to the Australian and international community as a multiuse national park. North Queensland Bulk Ports Corporation (NQBP) is responsible for three major port facilities adjacent to the GBRWHA. NQBP partnered with TropWATER (James Cook University) to commence a long-term environmental monitoring and research program in the Ports of Mackay and Hay Point. The first year of continuous monitoring provided an excellent platform to understand water quality characteristics within and surrounding both ports. This period of work coincided with an El Nino period and allowed the collection of scientifically "lucrative" data, collection of continuous water quality data un-influenced by rainfall and catchment flows are rare. High frequency loggers positioned on the seafloor showed peak suspended sediment concentrations and light attenuation every 2 weeks coinciding with local climate conditions. Interestingly, during these times, suspended solid concentrations exceeded Government water quality guidelines even in the absence of any acute anthropogenic activities. The use of satellite images were not particularly useful in mapping surface turbidity during low flow conditions, but could improve when normal rainfall patterns return again, but was not particularly useful in determining water quality more generally in the region. This monitoring program demonstrates how short-term programs could generate misleading conclusions, and how long term strategic investment in environmental monitoring and stewardship is critical in supporting ongoing port management decisions. Having long-term, rigorous environmental information is key to managing, minimising, and contextualising marine and coastal environmental change.
Light thresholds for seagrasses of the GBR: a synthesis and guiding document. Including knowledge... more Light thresholds for seagrasses of the GBR: a synthesis and guiding document. Including knowledge gaps and future priorities. Report to the National Environmental Science Programme. Reef and Rainforest Research Centre Limited, Cairns (41pp.).
The effects of climate on seagrasses in the Torres Strait: 2011-2014
The Seagrass Ecology Group from James Cook University’s Centre for Tropical Water & Aquatic E... more The Seagrass Ecology Group from James Cook University’s Centre for Tropical Water & Aquatic Ecosystem Research (JCU TropWATER),in collaboration with the Torres Strait Regional Authority Land and Sea Management Unit (TSRA LSMU), established a research program from 2011 to 2014 to develop critical information for the management of dugong and turtle in the Torres Strait by understanding how their key food resource, seagrass, is affected by environmental change. An intertidal seagrass monitoring site was established at Mabuiag Island where information on seagrass biomass and species composition, and environmental data including irradiance (light), global solar exposure, daytime tidal air exposure, mean and maximum daily water temperature, rainfall, wind speed and salinity, were collected. Seagrasses at Mabuiag Island undergo distinct seasonal changes in biomass and species composition during summer, while biomass and species composition remain relatively stable between autumn and spring. Changes in biomass were driven by changes in total hours of daytime tidal exposure, maximum daily water temperature, mean daily irradiance and total rainfall in the 30 days prior to when biomass estimates were made. Changes in species composition were driven by total hours of daytime tidal air exposure, global solar exposure, and maximum daily water temperature. The negative effect of periods of peak maximum daily water temperature on seagrass growth indicates that Mabuiag Island’s intertidal seagrasses already live at the upper limit of their thermal tolerance. Projected future increases in sea temperature are likely to have negative consequences for these shallow coastal meadows, which in turn may have profound implications for local dugong, turtle and commercial fisheries species. Management of seagrass resources in the Torres Strait should be focused on minimising any anthropogenic impacts to seagrass to ensure resilience to cumulative stressors of local seagrass populations remain high. Results from this study highlight the importance of environmental drivers of seagrass change, and the benefits of monitoring over longer time periods to gain a more accurate understanding of seagrass dynamics. We recommend: 1. Commence a monitoring program of subtidal seagrass meadows for a similar time frame (3-4 years) to assess the relationship between subtidal seagrass biomass and species composition with environmental variables. 2. Commence manipulative experimental research to establish how Torres Strait seagrasses respond to some of the predicted effects of climate change, particularly to determine the thermal tolerance of different seagrass species found in Torres Strait. 3. Incorporate information collected from the present study and (1) and (2) to model the consequences of climate change on Torres Strait intertidal and subtidal seagrass to develop appropriate dugong and turtle management strategies that account for predicted changes in seagrass meadows.
Seagrass mapping synthesis: a resource for coastal management in the Great Barrier Reef World Heritage Area
Spatial data as a baseline for managing coastal seagrasses in Queensland, Australia
Collation of spatial seagrass data from 1984 - 2014 for the Great Barrier Reef World Heritage Area
Light thresholds for seagrasses of the GBR: a synthesis and guiding document. Including knowledge... more Light thresholds for seagrasses of the GBR: a synthesis and guiding document. Including knowledge gaps and future priorities. Report to the National Environmental Science Programme. Reef and Rainforest Research Centre Limited, Cairns (41pp.).
Port of Mackay and Hay Point Ambient Marine Water Quality Monitoring Program (July 2014 to July 2015)
[Summary] Background. 1. North Queensland Bulk Ports commissioned an ambient marine water quality... more [Summary] Background. 1. North Queensland Bulk Ports commissioned an ambient marine water quality monitoring program for the region surrounding the Ports of Mackay and Hay Point. The primary objective of this program has been to develop a long term understanding of the marine water quality characteristics for the region. 2. This program has included a combination of spot field measurements and high frequency continuous data loggers, laboratory analysis for nutrient, herbicides and heavy metals, and satellite image to examine the influence of river plumes on regional water quality. 3. Thirteen sites make up this program, extending approximately 60km along the Mackay coastline from Slade Point to Freshwater Point, and offshore to Keswick Island. Sites in the network align with either key sensitive receptor habitats (e.g., corals or seagrass), or with key features in the study region (e.g., river flow points). 4. The program commenced July 2014, and this report presents the first 12 months of monitoring.
Ecological Indicators, Feb 1, 2021
Seagrass condition, resilience and ecosystem services are affected by the below-ground tissues (B... more Seagrass condition, resilience and ecosystem services are affected by the below-ground tissues (BGr) but these are rarely monitored. In this study we compiled historical data across northern Australia to investigate biomass allocation strategies in 13 tropical seagrass species. There was sufficient data to undertake statistical analysis for five species: Cymodocea serrulata, Halophila ovalis, Halodule uninervis, Thalassia hemprichii, and Zostera muelleri. The response of below-ground biomass (BGr) to above-ground biomass (AGr) and other environmental and seagrass community composition predictor variables were assessed using Generalized Linear Models. Environmental data included: region, season, sediment type, water depth, proximity to land-based sources of pollution, and a light stress index. Seagrass community data included: species diversity and dominant species class (colonising, opportunistic or persistant) based on biomass. The predictor variables explained 84-97% of variance in BGr on the log-scale depending on the species. Multi-species meadows showed a greater investment into BGr than mono-specific meadows and when dominated by opportunistic or persistent seagrass species. This greater investment into BGr is likely to enhance their resistance to disturbances if carbohydrate storage reserves also increase with biomass. Region was very important for the estimation of BGr from AGr in four species (not in C. serrulata). No temporally changing environmental features were included in the models, therefore, they cannot be used to predict local-scale responses of BGr to environmental change. We used a case study for Cairns Harbour to predict BGr by applying the models to AGr measured at 362 sites in 2017. This case study demonstrates how the model can be used to estimate BGr when only AGr is measured. However, the general approach can be applied broadly with suitable calibration data for model development providing a more complete assessment of seagrass resources and their potential to provide ecosystem services.
Limnology and oceanography letters, May 10, 2021
Seagrass meadows occupy shallow coastal waters of all continents except Antarctica. Their proximi... more Seagrass meadows occupy shallow coastal waters of all continents except Antarctica. Their proximity to coastal processes exposes them to anthropogenic impacts and the loss of well documented ecological services. We surveyed seagrass meadows over a 35-year period, including along 2500 km of coastline within the Great Barrier Reef World Heritage Area (GBRWHA). Included are data from intertidal to 123 m deep with seagrass found as deep as 76 m. There are few spatial data sets available that can be used by the global research community that follow long-term changes in seagrass meadow characteristics, and no validated long-term data sets for the Indo-Pacific that we know of. We provide this data on historical seagrass occurrence across the GBRWHA so that past and future changes can be assessed.
Great Barrier Reef Marine Park Authority, 2019
The Great Barrier Reef Marine Park Authority acknowledges the continuing sea country management a... more The Great Barrier Reef Marine Park Authority acknowledges the continuing sea country management and custodianship of the Great Barrier Reef by Aboriginal and Torres Strait Islander Traditional Owners whose rich cultures, heritage values, enduring connections and shared efforts protect the Reef for future generations.
Global seagrass research and assessment efforts have focused on shallow coastal and estuarine sea... more Global seagrass research and assessment efforts have focused on shallow coastal and estuarine seagrass populations. Comparatively little is known about the dynamics of deep-water (>10m) seagrasses despite evidence they form extensive meadows in some parts of the world and may be highly productive compared with their shallow counterparts. Deep-water seagrasses are subject to a similar range of anthropogenic threats as shallow meadows particularly along the Great Barrier Reef (GBR) in Queensland, where they occur close to major population centres and adjacent to the coast. We examine the dynamics of deep-water seagrass populations in the GBR through a range of research studies including long term (>8 years) assessments of change; impacts of major dredging programs; resilience and recovery from severe tropical storms and; targeted research investigating the drivers, thresholds and tolerances behind seasonal and inter-annual change. Collectively these re- search programs have prov...
Development of a molecular biology tool kit to monitor dredging-related light stress in the seagrass Zostera muelleri ssp. capricorni in Port Curtis
Key outcomes: This report provides a summary of field and laboratory studies conducted in the cou... more Key outcomes: This report provides a summary of field and laboratory studies conducted in the course of the development and validation of a set of molecular markers to monitor low light stress in the intertidal seagrass species Zostera muellerissp. capricorni. This is the first molecular study to establish and validate stress markers in an Australian seagrass species. The report also details how these markers can be used as a rapid assessment tool of seagrass health and be applied in active management of activities that impact on the light environment such as dredging. The key outcomes of these studies are: •We have successfully developed a seagrass health molecular tool kit based on real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) technology. This molecular tool kit was established by screening a total of 28 genes and includes a set of 10 reference genes and seven target genes (four early and three late sublethal markers of low light stress). •The mo...
Seagrass Habitat of Mourilyan Harbour: annual monitoring report: 2015
[Key Findings] 1. Overall seagrasses in Mourilyan Harbour remained in a very poor state with the ... more [Key Findings] 1. Overall seagrasses in Mourilyan Harbour remained in a very poor state with the continued absence of seagrass in all the intertidal monitoring meadows. 2. The subtidal channel meadow reduced in size and mean biomass from the previous year but remained in a good condition by historical standards. 3. Only one species (Halophila decipiens) was present in the monitoring meadows, however the first study of the broader harbour environment since 2000 recorded small meadows and isolated patches of Halodule uninervis, Enhalus acoroides and Halophila ovalis elsewhere in the harbour. 4. The foundation species (Zostera muelleri and Ha lodule uninervis) that had been continually present since monitoring began in 1993 until 2009 were absent for the sixth consecutive year. 5. The lack of recovery in foundation species despite improved growing conditions from 2012 may be due to a lack of seagrass propagules. Seedbank surveys over the last four years have found very low densities of Z. muelleri seeds, and in 2015 seeds were entirely absent. 6. In a regional context, seagrass at all long-term monitoring sites in the wet and dry tropics regions und erwent severe declines from 2009-11. Meadows to the north (Cairns Harbour) and south (Townsville) have now shown substantial recovery. Mourilyan Harbour remains the only location where no recovery of the key high biomass foundation species has occurred. 7. It is likely that assisted restoration will be required to re-establish viable Zostera muelleri in Mourilyan Harbour, given the lack of a seedbank and the areas isolation from any healthy nearby populations from which seeds or propagules could disperse.
The growth, survival and depth penetration of seagrass is directly related to light availability,... more The growth, survival and depth penetration of seagrass is directly related to light availability, which drives photosynthesis. The amount of light reaching seagrass beds is highly variable and can be easily disrupted by human activities, such as dredging. Dredging results in increased turbidity and decreased light penetration to the seagrass beds, invariably influencing overall productivity and seagrass health. To better understand seagrass light requirements and resilience to environmental stressors such as dredging requires knowledge on seagrass photophysiology and the impact air exposure during a tidal cycle has on photosynthesis. Oxygen, fluorescence and bio-optical properties were measured over a tidal cycle in seagrass beds of Zostera capricorni and Halophila ovalis in Gladstone Harbour to provide insight into the variability in carbon production in intertidal seagrass meadows. Both species showed an increase in photosynthetic activity with increased irradiance as the tide rec...
The use of appropriate indicators to evaluate condition is particularly important for habitats li... more The use of appropriate indicators to evaluate condition is particularly important for habitats like seagrass meadows where dramatic changes in distribution and species composition can occur. We used annual long-term monitoring data (2002-2014) to develop a report card of seagrass condition for 15 seagrass meadows at Gladstone as part of the Gladstone Healthy Harbours Partnership. The process used expert opinion to determine the best indicators of seagrass condition (above-ground biomass, meadow area, species composition), trialled four approaches to determine baseline condition of each indicator (a running longterm average, a 10-year fixed average, and two 5-year fixed average periods), and defined five threshold levels (very good, good, fair, poor, very poor) to grade each meadow relative to the baseline. Threshold levels for each condition category were adjusted based on the historical stability (variability) in each meadow's biomass and area. The 10-year fixed average was the...
Proceedings of the National Academy of Sciences, 2020
Significance Consumption transfers energy and materials through food chains and fundamentally inf... more Significance Consumption transfers energy and materials through food chains and fundamentally influences ecosystem productivity. Therefore, mapping the distribution of consumer feeding intensity is key to understanding how environmental changes influence biodiversity, with consequent effects on trophic transfer and top–down impacts through food webs. Our global comparison of standardized bait consumption in shallow coastal habitats finds a peak in feeding intensity away from the equator that is better explained by the presence of particular consumer families than by latitude or temperature. This study complements recent demonstrations that changes in biodiversity can have similar or larger impacts on ecological processes than those of climate.
Global Change Biology, 2021
Australia's Great Barrier Reef (GBR) catchments include some of the world's most intact c... more Australia's Great Barrier Reef (GBR) catchments include some of the world's most intact coastal wetlands comprising diverse mangrove, seagrass and tidal marsh ecosystems. Although these ecosystems are highly efficient at storing carbon in marine sediments, their soil organic carbon (SOC) stocks and the potential changes resulting from climate impacts, including sea level rise are not well understood. For the first time, we estimated SOC stocks and their drivers within the range of coastal wetlands of GBR catchments using boosted regression trees (i.e. a machine learning approach and ensemble method for modelling the relationship between response and explanatory variables) and identified the potential changes in future stocks due to sea level rise. We found levels of SOC stocks of mangrove and seagrass meadows have different drivers, with climatic variables such as temperature, rainfall and solar radiation, showing significant contributions in accounting for variation in SOC ...
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Papers by Michael Rasheed