Seagrass seed bank spatial structure and function following a large-scale decline

2021 ◽  
Vol 665 ◽  
pp. 75-87
Author(s):  
JC Jarvis ◽  
SA McKenna ◽  
MA Rahseed
Keyword(s):  
Spatial Structure ◽  
Water Depth ◽  
Seed Bank ◽  
Large Scale ◽  
Halophila Ovalis ◽  
World Heritage Area ◽  
Species Specific ◽  
And Function ◽  
Heritage Area

We examined the spatial structure (distribution, density) and function (viability) of the seagrass sediment seed bank, the storage of viable propagules (e.g. seeds, tubers, diaspores) in the sediment over time,in the northern Great Barrier Reef World Heritage Area in Cairns, Queensland, following a large-scale decline in seagrass area. A spatially explicit seagrass seed bank analysis was paired with a long-term annual assessment of seagrass distribution to assess seed bank spatial patterns and their relationship with the recovery and presence of seagrass, and water depth. Four years post-decline, the seed bank contained Zostera muelleri, Halodule uninervis, Halophila ovalis and Cymodocea serrulata seeds. Seed banks reflected adjacent meadow community composition; however, the density of seeds for all recorded species was significantly lower than analogous seagrass populations, indicating a reduction in the capacity for recovery from the seed bank. A spatial structure existed in both the total (viable + non-viable) and viable seed bank, and distance between seed clusters ranged from 50-550 m depending on species and seed type. Observed patterns in clustering may be explained by variation in water depth and the past distribution of seagrass in these meadows. These results demonstrate that the distribution of seagrass seeds within the seed bank, which directly influences the natural recovery of seagrass communities, is not uniform across species and may result in patchy recovery of the meadows. Therefore, the resilience provided by the seed bank in seagrass communities should not be viewed as a static level of insurance for the entire meadow, but rather as dynamic and species-specific, with variability over both space and time.

Depauperate seed banks in urban tropical seagrass meadows

2020 ◽  
Vol 71 (8) ◽  
pp. 935
Author(s):  
Glendon Hong Ming Ong ◽  
Samantha Lai ◽  
Siti Maryam Yaakub ◽  
Peter Todd
Keyword(s):  
Seed Bank ◽  
Large Scale ◽  
Seed Viability ◽  
Seed Banks ◽  
Dormant Seed ◽  
Seagrass Meadows ◽  
Halophila Ovalis ◽  
The Status ◽  
Cymodocea Rotundata

Seagrasses need to be resilient if they are to persist in the long term. Being able to build up a dormant seed bank in sediments is a key strategy that some species employ to regenerate from large-scale degradation. Much of the research on seed banks has focussed on temperate species, and little is known regarding the status of seed banks in tropical meadows. In the present study, we examined the seed bank status of three common seagrass species at six sites in Singapore and attempted to identify potential drivers of seed abundance. Our results indicated depauperate seed banks with few species setting viable seed and low seed densities. Halophila ovalis seeds were found at four sites and Halodule uninervis seeds at two sites, but Cymodocea rotundata seeds were absent from all six sites. Whereas H. ovalis seed viability ranged from 20% to 68.8%, none of the H. uninervis seeds was viable. Halophila ovalis seed densities (33–334m–2) were much higher than those of H. uninervis (9–21m–2). Of the variables examined, only H. ovalis cover was positively correlated with the number of seeds. Our study has highlighted the vulnerability of seagrass meadows in Singapore’s urban waters to future disturbances.

Tourism and Natural World Heritage: A Complicated Relationship

2017 ◽  
Vol 57 (5) ◽  
pp. 563-578 ◽  
Author(s):  
Ralf Buckley
Keyword(s):  
Private Equity ◽  
Large Scale ◽  
World Heritage ◽  
Natural World ◽  
Small Scale ◽  
Legal Structure ◽  
World Heritage Area ◽  
Political Economic ◽  
Heritage Area

There are legal, political, economic, social, and environmental links between tourism and World Heritage Areas, some straightforward but others controversial. These are examined here as aspects of a long-term, stable, but complicated, relationship. Management of small-scale mobile tourism operations is well established. It includes activities, equipment, timing, numbers, group size, marketing, fees, and permit latency. Management of large-scale fixed-site tourism infrastructure and accommodation involving private equity or operational control is more controversial. It includes legal structure of partnership arrangements, and allocation of revenues, costs, and risks. The relationship framework shows the importance of picking partners carefully and establishing mechanisms for external counseling. Research opportunities include: the marketing value of World Heritage Area (WHA) controversies; the tourism effects of In Danger declarations; funding models; and impact assessment, stakeholder roles, and co-management mechanisms, in different jurisdictions. Quantifying these effects needs large-scale compilation and comparison of case studies.

scholarly journals Common species link global ecosystems to climate change: dynamical evidence in the planktonic fossil record

2017 ◽  
Vol 284 (1858) ◽  
pp. 20170722 ◽  
Author(s):  
Bjarte Hannisdal ◽  
Kristian Agasøster Haaga ◽  
Trond Reitan ◽  
David Diego ◽  
Lee Hsiang Liow
Keyword(s):  
Large Scale ◽  
Planktonic Foraminifera ◽  
Deep Ocean ◽  
Common Species ◽  
Ecosystem Structure ◽  
Environmental Forcing ◽  
Widespread Species ◽  
Quantitative Evidence ◽  
And Function

Common species shape the world around us, and changes in their commonness signify large-scale shifts in ecosystem structure and function. However, our understanding of long-term ecosystem response to environmental forcing in the deep past is centred on species richness, neglecting the disproportional impact of common species. Here, we use common and widespread species of planktonic foraminifera in deep-sea sediments to track changes in observed global occupancy (proportion of sampled sites at which a species is present and observed) through the turbulent climatic history of the last 65 Myr. Our approach is sensitive to relative changes in global abundance of the species set and robust to factors that bias richness estimators. Using three independent methods for detecting causality, we show that the observed global occupancy of planktonic foraminifera has been dynamically coupled to past oceanographic changes captured in deep-ocean temperature reconstructions. The causal inference does not imply a direct mechanism, but is consistent with an indirect, time-delayed causal linkage. Given the strong quantitative evidence that a dynamical coupling exists, we hypothesize that mixotrophy (symbiont hosting) may be an ecological factor linking the global abundance of planktonic foraminifera to long-term climate changes via the relative extent of oligotrophic oceans.

Ecological restoration for biodiversity conservation triggers response of bark beetle pests and their natural predators

2020 ◽  
Author(s):  
Anne-Maarit Hekkala ◽  
Simon Kärvemo ◽  
Martijn Versluijs ◽  
Jan Weslien ◽  
Christer Björkman ◽  
...  
Keyword(s):  
Ecological Restoration ◽  
Bark Beetle ◽  
Boreal Forests ◽  
Bark Beetles ◽  
Large Scale ◽  
Prescribed Burning ◽  
Gap Cutting ◽  
Population Sizes ◽  
And Function

Abstract The restoration of forest structure and function is increasingly being used in boreal forests in order to halt the loss of biodiversity. Often ecological restoration is aimed at increasing the volume of dead and dying trees to enhance the biodiversity of deadwood-dependent organisms, but it may also increase population sizes of pest bark beetle species, even several years following restoration. Herein, we used a large-scale restoration experiment in Northern Sweden to assess the 5 years post-restoration effects of restorative gap cutting and prescribed burning on the populations of a set of economically harmful pest bark beetles (Ips typographus, Polygraphus poligraphus, Tomicus piniperda and Pityogenes chalcographus) and the most important predators of bark beetles, Thanasimus spp. In addition, we assessed the effects of forest stand characteristics at stand and landscape scale on the abundance of I. typographus. Five years post-restoration, gap-cut stands supported the highest abundances of P. poligraphus and contained the highest count of spruce trees newly attacked by bark beetles. By contrast, prescribed burning generally sustained the lowest abundances of pest bark beetles, especially I. typographus and P. poligraphus, and the highest abundance of their natural predators Thanasimus spp. The population abundance of I. typographus was also positively affected by the area of clear cuts within a 500 m radius from the stand. In conclusion, prescribed burning appears to be a safer method for ecological restoration than gap cutting in the long-term. According to our results, a risk of a local bark beetle outbreak still remains 5 years following the initiation of ecological restoration treatments on spruce-dominated mature gap-cut stands.

scholarly journals Effects of Waves and Sediment Disturbance on Seed Bank Persistence at Tidal Flats

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhenchang Zhu ◽  
Tjeerd J. Bouma ◽  
Qin Zhu ◽  
Yanpeng Cai ◽  
Zhifeng Yang
Keyword(s):  
Climate Change ◽  
Seed Bank ◽  
Large Scale ◽  
Environmental Changes ◽  
Tidal Flats ◽  
Coastal Vegetation ◽  
Climate Change Effects ◽  
Sediment Disturbance ◽  
Seed Bank Dynamics

Coastal wetlands such as salt marshes have been increasingly valued for their capacity to buffer global climate change effects, yet their long-term persistence is threatened by environmental changes. Whereas, previous studies largely focused on lateral erosion risk induced by stressors like sea level rise, it remains poorly understood of the response of lateral expansion to changing environments. Seedling establishment is a key process governing lateral marsh expansion as seen in many coastal regions such as Europe and East Asia. Here, we evaluate mechanistically the response of seed bank dynamics to changing physical disturbance at tidal flats, using the globally common coastal foundation plant, cordgrass as a model. We conducted a large-scale field study in an estuary in Northwest Europe, where seed bank dynamics of cordgrass in the tidal flats was determined and linked to in situ hydrodynamics and sediment dynamics. The results revealed that wave disturbance reduced the persistence of seeds on the surface, whereas amplified sediment disturbance lowered the persistence of both surface and buried seeds. Overall, this indicates that increasing storminess and associated sediment variability under climate change threatens seed bank persistence in tidal flats, and hence need urgently be incorporated into models for long-term bio-geomorphological development of vegetated coastal ecosystems. The knowledge gained here provides a basis for more accurate predictions on how climatically driven environmental changes may alter the fitness, resilience and persistence of coastal foundation plants, with significant implications for nature-based solutions with coastal vegetation to mitigate climate change effects.

A comparative assessment of approaches and outcomes for seagrass revegetation in Shark Bay and Florida Bay

2012 ◽  
Vol 63 (11) ◽  
pp. 984 ◽  
Author(s):  
John Statton ◽  
Kingsley W. Dixon ◽  
Renae K. Hovey ◽  
Gary A. Kendrick
Keyword(s):  
Florida Bay ◽  
Cost Effective ◽  
Shark Bay ◽  
Commercial Activities ◽  
History Of ◽  
World Heritage Area ◽  
Short Time ◽  
Time Frames ◽  
Heritage Area

Here, we review the literature to evaluate seagrass revegetation projects focussed on Posidonia australis and Amphibolis antarctica, the main affected species in Shark Bay in the World Heritage Area in Western Australia, together with projects from Florida Bay, an analogous system with a long history of seagrass revegetation. We assessed the effectiveness of anchoring planting units, plant-unit density and size on planting-unit survival. We found no positive trends in our assessment, suggesting that there is no discrete technique, approach or technology that could be used with confidence to deliver cost-effective, scalable revegetation. Of concern was that revegetation success was evaluated over comparatively short time frames (1–3 years), driven by the strict time frames or deadlines of governing grant funding and commercial activities, leading to concerns that long-term revegetation outcomes may be difficult to assess with confidence. Several factors influenced revegetation outcomes which were grouped into three ‘filter’ categories; abiotic, biotic and socioeconomic. We recommend that future revegetation programs involving seagrass have greater emphasis on understanding how these filters act independently or collectively to drive successful revegetation as well as developing cost-effective, proven and scalable technology supported by longer-term monitoring to ensure revegetation programs do achieve the desired ecological outcomes.

scholarly journals Aboriginal marine subsistence foraging flexibility in a dynamic estuarine environment: The late development of Tin Can Inlet (southeast Queensland) middens revisited

2019 ◽  
Vol 22 ◽  
pp. 1-38 ◽  
Author(s):  
Tam Smith ◽  
Ian J. McNiven
Keyword(s):  
Sea Level ◽  
Historical Ecology ◽  
Sea Level Changes ◽  
The Past ◽  
Past 2000 Years ◽  
Regional Sea Level ◽  
World Heritage Area ◽  
Species Specific ◽  
Heritage Area ◽  
Southeast Queensland

Although the sea arrived in southeast Queensland around 8000 years ago, most estuarine middens date to the past 1000 years. An example is midden deposits dating to the past 400 years forming the upper levels of Sites 62 and 75b from Tin Can Inlet located immediately south of the Fraser Island (K’gari) World Heritage Area. Both sites were excavated and analysed in the 1980s. This paper revisits these results following a detailed re-analysis of midden materials and new insights on regional sea level changes. Taking an historical ecology approach, species-specific habitat requirements and associated substrate sediment dynamics help explain similarities and differences between the two midden shell assemblages. Environmental factors and the location of both sites on landforms that formed following sea level fall over the past 2000 years help explain why the basal levels of both sites are probably <1000–1500 years old. Documenting pre-2000-year-old Aboriginal use of Tin Can Inlet will need to target more elevated inland dune deposits (>5m ASL) fronting the mid-Holocene sea level highstand palaeoshoreline.

scholarly journals Lahars of Ruapehu Volcano, New Zealand: risk mitigation

2007 ◽  
Vol 45 ◽  
pp. 155-162 ◽  
Author(s):  
Harry J.R. Keys
Keyword(s):  
Risk Mitigation ◽  
Public Consultation ◽  
Warning Systems ◽  
Active Response ◽  
World Heritage Area ◽  
High Level ◽  
Heritage Area ◽  
Political Decision Making ◽  
Ruapehu Volcano

AbstractA dam-break lahar resulting from the last eruption of Ruapehu is expected when Crater Lake reaches a critical high level, probably within the next 1–5 summers. A high level of public consultation, political decision-making and ongoing scientific input has occurred to address the risks. Decisions about managing lahar risk have taken into account the fact that lahars are common on the active Ruapehu Volcano (2797 m) and in valleys draining the mountain and that most lahars are generated by eruptions, about half of which have no useful precursors. Lahars threaten New Zealand’s largest ski area and nationally important infrastructure. Public safety has been the main consideration but the need for long-term risk mitigation and reducing impacts on Tongariro National Park World Heritage Area have also been important. Lahar mitigation on Ruapehu now includes six lahar warning systems, each with active response plans, and some infrastructure isolated from or hardened against lahars.

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