Seagrass meadows in a globally changing environment

Seagrass meadows are valuable ecosystem service providers that are now being lost globally at an unprecedented rate, with water quality and other localised stressors putting their future viability in doubt. It is therefore critical that we learn more about the interactions between seagrass meadows and future environmental change in the anthropocene. This needs to be with particular reference to the consequences of poor water quality on ecosystem resilience and the effects of change on trophic interactions within the food web. Understanding and predicting the response of seagrass meadows to future environmental change requires an understanding of the natural long-term drivers of change and how these are currently influenced by anthropogenic stress. Conservation management of coastal and marine ecosystems now and in the future requires increased knowledge of how seagrass meadows respond to environmental change, and how they can be managed to be resilient to these changes. Finding solutions to such issues also requires recognising people as part of the social-ecological system. This special issue aims to further enhance this knowledge by bringing together global expertise across this field. The special issues considers issues such as ecosystem service delivery of seagrass meadows, the drivers of long-term seagrass change and the socio-economic consequences of environmental change to seagrass

Port of Karumba long term seagrass monitoring: October 2008

Seagrass habitats are valuable fisheries resources that provide critical ecological functions within the coastal zone. The wide distribution of seagrasses in Queensland and their capacity to show measurable, short-term responses to changes in water quality, make them ideal candidates for monitoring the health of marine and coastal environments.\ud \ud A network of long term seagrass monitoring sites has been established at various port locations throughout Queensland to assist port managers in the planning and development of port operations to achieve minimal impacts on the marine environment and fish habitats. The programs are also used as an indicator of the overall marine environmental health of ports and are an example of international best practice in the management of port environments.\ud \ud This report details the latest findings of the Port of Karumba long-term seagrass monitoring program incorporating data from the most recent survey conducted in October 2008. The Karumba monitoring program aims to ensure port activities have a minimal impact on seagrasses. It is also used to provide a measure of the marine environmental health of the port.\ud \ud Results of the 2008 monitoring find seagrass in Karumba to be in a healthy state, supporting dugong populations and providing a fisheries resource. Inter-annual variation in seagrass meadow area and density (i.e. biomass) continues to be large. Here we report strong evidence to suggest that throughout 15 years of monitoring seagrass variability has not been caused by local anthropogenic factors. Inter-tidal seagrass meadows in Karumba are thought to be principally driven by atmospheric temperature, tidal exposure and catchment rainfall.\ud \ud In conclusion, this survey indicates that human activities in Karumba, including dredging and other port and urban activities were unlikely to have had a significant impact on seagrasses in the area, and that the marine environment of the port was in a healthy condition

Long term seagrass monitoring in the Port of Thursday Island: March 2008

Seagrass habitats are valuable fisheries resources that show measurable responses to changes in water quality. These attributes make seagrass meadows ideal candidates for monitoring the long term health of marine environments. A network of long term seagrass monitoring sites has been established at various port locations throughout Queensland to assist port managers in the planning and development of port operations to achieve minimal impacts on the marine environment and fish habitats. The programs are also used as an indicator of the overall marine environmental health of ports and are an example of international best practise in the management of port environments. This report details the latest findings from the Port of Thursday Island long term seagrass monitoring program from the most recent survey conducted in March 2008.\ud \ud A baseline survey of seagrass habitat at the Port of Thursday Island in March 2002 identified some of the best examples of intertidal and subtidal seagrass habitat that have been found in Queensland. Nine seagrass meadows were selected for long term monitoring from the original baseline survey. The monitoring meadows were representative of the range of seagrass communities identified and encompassed those meadows located in areas likely to be vulnerable to impacts from port operations and developments. This current survey is the third of planned biennial long-term seagrass monitoring, with previous surveys conducted in March 2004 and 2006. The monitoring program assesses seagrass above ground biomass, individual meadow area and species composition (community types) and compares changes with previous surveys.\ud \ud The results of the March 2008 monitoring survey found that seagrasses in the Port of Thursday Island were generally in good condition. Seagrass meadow area was similar to that detected during previous monitoring while coastal meadows dominated by Halodule and Halophila were at similar densities to previous surveys. However, meadows dominated by the large growing species Enhalus acoroides appear to have been under greater stress in recent years resulting in a decline in density. These declines in Enhalus meadows are thought to be in response to a combination of natural climate and exposure related drivers but their continuing decline may be cause for concern in the future. As monitoring is only conducted every two years, the exact cause of these declines is difficult to interpret. However these changes were consistent with changes that had occurred for the same species in other nearby monitoring locations and were unlikely to be due to human or port activities

Seasonal dynamics, productivity and resilience of seagrass at the Port of Abbot Point: 2008-2010

This report details the results of seagrass baseline assessments, quarterly seagrass monitoring, and experimental research on seagrass resilience and productivity conducted between 2008 and 2010 at the Port of Abbot Point, North Queensland. This program of research and monitoring was commissioned by North Queensland Bulk Port (NQBP) Corporation in order to provide an understanding of the spatial and temporal change of seagrasses in the vicinity of the Port; their ecological and economic value, and their capacity to recover from future port related impacts.\ud \ud Seagrass coverage was extensive, with meadows comprising 42% of the survey area. Seagrass meadows occurred from the shoreline to a distance of approximately 10km offshore and covered an area of up to 21,000ha. The survey area contained a variety of species and meadow types ranging from low biomass coastal Halodule uninervis meadows, to higher biomass deep water Halophila spinulosa meadows. Small meadows comprising the larger leaved species Zostera capricorni and Cymodocea serrulata were also recorded.\ud \ud Seagrasses at Abbot Point were highly dynamic, changing as a function of season, but also influenced by extreme weather events during the life of the study. The productivity and resultant biomass of seagrasses at Abbot Point reached a maximum in the late dry season, a trend consistent with observations of seagrasses throughout Queensland.\ud \ud Seagrass meadows at Abbot Point were highly productive, producing 237 grams of carbon per m² per day. Although this is roughly half the productivity of seagrass meadows on reef platforms in the Torres Strait, this net productivity compares highly with many productive marine and terrestrial ecosystems worldwide. The productivity of these seagrasses supports an abundant and diverse fauna, with many species of economically important Penaeid prawns utilising the seagrass meadows of Abbot Point. This is in addition to the presence of a range of endangered and migratory mega fauna such as Dugong, Turtle and Humpback whale observed in proximity to the port.\ud \ud Seagrasses at Abbot Point were found to have some levels of resilience to stress, however this varied with species and community type and will be dependent in the future upon the continued availability of seed reserves. Species such as Halophila spinulosa were found to have a high capacity for recovery through the use of seed reserves in the sediment, however shallow near- shore species such as Halodule uninervis failed to recover quickly from simulated disturbance, relying on asexual propagation and were more vulnerable to longer term impacts should widespread loss occur.\ud \ud Seagrass meadows at the Port of Abbot Point are highly productive and provide habitat and food for a range of important fauna. These seagrass meadows are dynamic, with some habitats having a higher capacity for recovery from loss than others. They are currently subject to a range of anthropogenic and natural threats potentially reducing their resilience to increased cumulative impact. The available information indicates that future developments that may potentially disturb the local water quality (particularly light availability) at Abbot Point need to be carefully managed to ensure the longer term viability of seagrasses. The program presented here can form the basis of a seagrass assessment and monitoring strategy to aid in the management of dredge related impacts

Port of Weipa Long Term Seagrass Monitoring: September 2010

Seagrass habitats provide important ecological functions in the coastal zone including provision of primary productivity in the marine environment and nursery habitat for key fisheries species. The wide distribution on seagrasses in Queensland, and their capacity to show measurable responses to changes in water quality make them ideal candidates for monitoring the health of the marine environments. A network of long term seagrass monitoring sites has been established at various port locations throughout Queensland to assist Fisheries Queensland and port managers in planning and management to ensure port activities are having a minimal impact on the marine environment and fish habitats. The program is also used to help separate natural from anthropogenic change to seagrass meadows. This report details the results of the September 2010 monitoring program in the Port of Weipa. Seagrasses in the Port of Weipa remained in a reasonable but vulnerable condition. Several meadows that had shown a long term declining trend since monitoring began in 2000 recorded a significant increase for the first time in 2010. The declines were likely associated with natural shifts in tidal exposure and changes in light and temperature associated with local climate conditions. The declines had been particularly concerning for Enhalus acoroides meadows, especially the large intertidal meadow opposite Lorim Point, where biomass reached a record low in 2008. In response to the declines, North Queensland Bulk Ports (NQBP) and Fisheries Queensland conducted an additional survey in both April 2009 and May 2010 to determine whether the large Enhalus meadow was in a healthier state outside of the regular survey period. The additional survey found that biomass was also significantly lower than found in past assessments at a similar time of year. During the regular September 2010 monitoring survey, mean above-ground biomass in the large Enhalus meadow of most concern had increased significantly from the previous year and was significantly higher than the past five years of monitoring. The intertidal Halodule uninervis meadow on the Western bank of the Hey River had also re-established after disappearing in 2009. Changes in biomass for these meadows over the course of the monitoring program are significantly correlated with the amount of daytime tidal exposure in the month prior to the survey as well as the amount of solar radiation in the twelve months prior to monitoring. Seagrasses appear to have been resilient to the impacts associated with regular port maintenance dredging during the life of the current monitoring program. However, despite the positive signs of recovery for Enhalus meadows in the port, they are still in a potentially vulnerable state. An examination of light and temperature conditions at vulnerable seagrass meadows established in the port after the September 2010 survey will significantly enhance the ability of the monitoring program to pinpoint the causes of seagrass change. These data are currently being collected and results will be included the 2011 report

Port of Weipa Long Term Seagrass Monitoring: September 2010

Seagrass habitats provide important ecological functions in the coastal zone including provision of primary productivity in the marine environment and nursery habitat for key fisheries species. The wide distribution on seagrasses in Queensland, and their capacity to show measurable responses to changes in water quality make them ideal candidates for monitoring the health of the marine environments. A network of long term seagrass monitoring sites has been established at various port locations throughout Queensland to assist Fisheries Queensland and port managers in planning and management to ensure port activities are having a minimal impact on the marine environment and fish habitats. The program is also used to help separate natural from anthropogenic change to seagrass meadows.\ud \ud This report details the results of the September 2010 monitoring program in the Port of Weipa. Seagrasses in the Port of Weipa remained in a reasonable but vulnerable condition. Several meadows that had shown a long term declining trend since monitoring began in 2000 recorded a significant increase for the first time in 2010. The declines were likely associated with natural shifts in tidal exposure and changes in light and temperature associated with local climate conditions. The declines had been particularly concerning for Enhalus acoroides meadows, especially the large intertidal meadow opposite Lorim Point, where biomass reached a record low in 2008. In response to the declines, North Queensland Bulk Ports (NQBP) and Fisheries Queensland conducted an additional survey in both April 2009 and May 2010 to determine whether the large Enhalus meadow was in a healthier state outside of the regular survey period. The additional survey found that biomass was also significantly lower than found in past assessments at a similar time of year.\ud \ud During the regular September 2010 monitoring survey, mean above-ground biomass in the large Enhalus meadow of most concern had increased significantly from the previous year and was significantly higher than the past five years of monitoring. The intertidal Halodule uninervis meadow on the Western bank of the Hey River had also re-established after disappearing in 2009. Changes in biomass for these meadows over the course of the monitoring program are significantly correlated with the amount of daytime tidal exposure in the month prior to the survey as well as the amount of solar radiation in the twelve months prior to monitoring.\ud \ud Seagrasses appear to have been resilient to the impacts associated with regular port maintenance dredging during the life of the current monitoring program. However, despite the positive signs of recovery for Enhalus meadows in the port, they are still in a potentially vulnerable state. An examination of light and temperature conditions at vulnerable seagrass meadows established in the port after the September 2010 survey will significantly enhance the ability of the monitoring program to pinpoint the causes of seagrass change. These data are currently being collected and results will be included the 2011 report

Port of Abbot Point seagrass baseline surveys: wet & dry season 2008

The Port of Abbot Point, approximately 25km north of Bowen, forms part of the State Government’s infrastructure development plan for the Northern Economic Triangle. To complement a planned industrial precinct at Abbot Point, the Ports Corporation of Queensland Limited (PCQ) is investigating options to expand the current port and develop a Multi Cargo Facility (MCF). As part of the planning for this project, PCQ has commissioned the Marine Ecology Group at the Department of Primary Industries and Fisheries (DPI&F) to conduct seagrass baseline assessments and monitoring programs. The seagrass studies will assist in planning for the development so as to minimize impacts on seagrass habitats and to develop appropriate management and mitigation measures. This report describes the baseline seagrass assessments undertaken during 2008. Results detail the seasonal abundance, species composition, and distribution of seagrass communities surrounding Abbot Point including those potentially affected by proposed port developments. It also provides the foundation to establish long-term monitoring and to asses future seagrass changes. Seagrass coverage was extensive with meadows comprising 42% of the survey area covering the inshore region from Branch Creek to Bowen. Seagrass meadows occurred from the shoreline to a distance of approximately 10km offshore. The survey area contained a variety of species and meadow types ranging from low biomass coastal Halodule uninervis meadows, to higher biomass deep water Halophila spinulosa meadows. The meadows identified within the Abbot Point port limits were likely to play a number of important ecological roles, including supporting endangered and threatened species such as dugong and turtles, providing nursery grounds for commercial fisheries species as well as providing a substantial component of the primary productivity for the regions marine ecosystem. Results of the seagrass baselines have already been used to assist with planning and design of port developments in a manner likely to minimise or reduce potential impacts. However the location of seagrass meadows throughout the port means they are likely to face some level of direct and indirect impact from port development. The second phase of the seagrass study is currently under way and aims to better quantify what these impacts are likely to be and includes quarterly monitoring of selected seagrass meadows to: • Assess natural seasonal and interannual variability in seagrass density and abundance; • Determine the value of seagrass meadows in terms of primary and fisheries productivity; • Determine capacity for, and rate of, recovery from disturbance Preliminary results of these ongoing studies are also presented in this report

Port of Abbot Point seagrass baseline surveys: wet & dry season 2008\ud

The Port of Abbot Point, approximately 25km north of Bowen, forms part of the State Government’s infrastructure development plan for the Northern Economic Triangle. To complement a planned industrial precinct at Abbot Point, the Ports Corporation of Queensland Limited (PCQ) is investigating options to expand the current port and develop a Multi Cargo Facility (MCF). As part of the planning for this project, PCQ has commissioned the Marine Ecology Group at the Department of Primary Industries and Fisheries (DPI&F) to conduct seagrass baseline assessments and monitoring programs. The seagrass studies will assist in planning for the development so as to minimize impacts on seagrass habitats and to develop appropriate management and mitigation measures.\ud \ud This report describes the baseline seagrass assessments undertaken during 2008. Results detail the seasonal abundance, species composition, and distribution of seagrass communities surrounding Abbot Point including those potentially affected by proposed port developments. It also provides the foundation to establish long-term monitoring and to asses future seagrass changes.\ud \ud Seagrass coverage was extensive with meadows comprising 42% of the survey area covering the inshore region from Branch Creek to Bowen. Seagrass meadows occurred from the shoreline to a distance of approximately 10km offshore. The survey area contained a variety of species and meadow types ranging from low biomass coastal Halodule uninervis meadows, to higher biomass deep water Halophila spinulosa meadows.\ud \ud The meadows identified within the Abbot Point port limits were likely to play a number of important ecological roles, including supporting endangered and threatened species such as dugong and turtles, providing nursery grounds for commercial fisheries species as well as providing a substantial component of the primary productivity for the regions marine ecosystem.\ud \ud Results of the seagrass baselines have already been used to assist with planning and design of port developments in a manner likely to minimise or reduce potential impacts. However the location of seagrass meadows throughout the port means they are likely to face some level of direct and indirect impact from port development. The second phase of the seagrass study is currently under way and aims to better quantify what these impacts are likely to be and includes quarterly monitoring of selected seagrass meadows to:\ud \ud • Assess natural seasonal and interannual variability in seagrass density and abundance;\ud \ud • Determine the value of seagrass meadows in terms of primary and fisheries productivity;\ud \ud • Determine capacity for, and rate of, recovery from disturbance\ud \ud Preliminary results of these ongoing studies are also presented in this report

Diel trophic structuring of seagrass bed fish assemblages in the Wakatobi Marine National Park, Indonesia

The faunal communities of seagrass beds throughout SE Asia are highly threatened by continued overexploitation, yet their ecology is poorly understood. Developing a greater understanding of the faunal linkages between seagrass beds and associated coastal habitats can facilitate more informed ecosystem level management. The present study used beach seine netting to sample seagrass bed fish assemblages in the Wakatobi Marine National Park, Indonesia, to investigate diel migrations of fish into and out of seagrass beds. These fish assemblages were found to be diverse relative to other studies within the region, with many species being economically important to local subsistence fisheries. The abundance, species richness and trophic structure of these fish assemblages changed with time of day indicating that fish populations are in a dynamic state. Mean fish abundance increased by ?45% from day to night (Day: 8.61 ± 0.13 fish 100 m?2; Night: 15.6 ± 1.4 fish 100 m?2) while mean species richness increased from 6.6 ± 1.9 per seine haul to 11.4 ± 0.2. Increasing abundance and diversity of fish at night suggests migration onto these habitats from nearby habitats such as reefs, mangroves or deep water; and/or increased activity of those fish resident within seagrass habitats. Division of species into trophic categories enabled the trophic structure of changing fish assemblages to be examined. Assemblages were dominated during both the day and night by invertebrate and fish feeders; however, a major diel change in trophic structure occurred in the abundance of omnivores. During the day omnivores were abundant, but they were replaced at night by exclusive invertebrate feeders. We therefore propose that diel changes in seagrass fish assemblages are predominantly structured by food availability, although other factors such as increased night-time shelter provision were also found to be important albeit to a much lesser extent. <br/