Emma L. Jackson

Use of a seagrass residency index to apportion commercial fishery landing values and recreation fisheries expenditure to seagrass habitat service.

Where they dominate coastlines, seagrass beds are thought to have a fundamental role in maintaining populations of exploited species. Thus, Mediterranean seagrass beds are afforded protection, yet no attempt to determine the contribution of these areas to both commercial fisheries landings and recreational fisheries expenditure has been made. There is evidence that seagrass extent continues to decline, but there is little understanding of the potential impacts of this decline. We used a seagrass residency index, that was trait and evidence based, to estimate the proportion of Mediterranean commercial fishery landings values and recreation fisheries total expenditure that can be attributed to seagrass during different life stages. The index was calculated as a weighted sum of the averages of the estimated residence time in seagrass (compared with other habitats) at each life stage of the fishery species found in seagrass. Seagrass-associated species were estimated to contribute 30%-40% to the value of commercial fisheries landings and approximately 29% to recreational fisheries expenditure. These species predominantly rely on seagrass to survive juvenile stages. Seagrass beds had an estimated direct annual contribution during residency of €58-91 million (4% of commercial landing values) and €112 million (6% of recreation expenditure) to commercial and recreational fisheries, respectively, despite covering <2% of the area. These results suggest there is a clear cost of seagrass degradation associated with ineffective management of seagrass beds and that policy to manage both fisheries and seagrass beds should take into account the socioeconomic implications of seagrass loss to recreational and commercial fisheries.

Identifying knowledge gaps in seagrass research and management: an Australian perspective

Seagrass species form important marine and estuarine habitats providing valuable ecosystem services and functions. Coastal zones that are increasingly impacted by anthropogenic development have experienced substantial declines in seagrass abundance around the world. Australia, which has some of the worlds largest seagrass meadows and is home to over half of the known species, is not immune to these losses. In 1999 a review of seagrass ecosystems knowledge was conducted in Australia and strategic research priorities were developed to provide research direction for future studies and management. Subsequent rapid evolution of seagrass research and scientific methods has led to more than 70% of peer reviewed seagrass literature being produced since that time. A workshop was held as part of the Australian Marine Sciences Association conference in July 2015 in Geelong, Victoria, to update and redefine strategic priorities in seagrass research. Participants identified 40 research questions from 10 research fields (taxonomy and systematics, physiology, population biology, sediment biogeochemistry and microbiology, ecosystem function, faunal habitats, threats, rehabilitation and restoration, mapping and monitoring, management tools) as priorities for future research on Australian seagrasses. Progress in research will rely on advances in areas such as remote sensing, genomic tools, microsensors, computer modeling, and statistical analyses. A more interdisciplinary approach will be needed to facilitate greater understanding of the complex interactions among seagrasses and their environment.

A Review of the Factors Influencing Spawning, Early Life Stage Survival and Recruitment Variability in the Common Cuttlefish (Sepia officinalis)

Global landings of cephalopods (cuttlefish, squid and octopus) have increased dramatically over the past 50 years and now constitute almost 5% of the total worlds fisheries production. At a time when landings of many traditional fin-fish stocks are continuing to experience a global decline as a result of over-exploitation, it is expected that fishing pressure on cephalopod stocks will continue to rise as the fishing industry switch their focus onto these non-quota species. However, long-term trends indicate that landings may have begun to plateau or even decrease. In European waters, cuttlefish are among the most important commercial cephalopod resource and are currently the highest yielding cephalopod group harvested in the north-east Atlantic, with the English Channel supporting the main fishery for this species. Recruitment variability in this short-lived species drives large fluctuations in landings. In order to provide sustainable management for Sepia officinalis populations, it is essential that we first have a thorough understanding of the ecology and life history of this species, in particular, the factors affecting spawning, early life stage (ELS) survival and recruitment variability. This review explores how and why such variability exists, starting with the impact of maternal effects (e.g. navigation, migration and egg laying), moving onto the direct impact of environmental variation on embryonic and ELSs and culminating on the impacts that these variations (maternal and environmental) have at a population level on annual recruitment success. Understanding these factors is critical to the effective management of expanding fisheries for this species.

Seagrass ecosystem services – What's next?

Seagrasses, marine flowering plants, provide a wide range of ecosystem services, defined here as natural processes and components that directly or indirectly benefit human needs. Recent research has shown that there are still many gaps in our comprehension of seagrass ecosystem service provision. Furthermore, there seems to be little public knowledge of seagrasses in general and the benefits they provide. This begs the questions: how do we move forward with the information we have? What other information do we need and what actions do we need to take in order to improve the situation and appreciation for seagrass? Based on the outcomes from an international expert knowledge eliciting workshop, three key areas to advance seagrass ecosystem service research were identified: 1) Variability of ecosystem services within seagrass meadows and among different meadows; 2) Seagrass ecosystem services in relation to, and their connection with, other coastal habitats; and 3) Improvement in the communication of seagrass ecosystem services to the public. Here we present ways forward to advance seagrass ecosystem service research in order to raise the profile of seagrass globally, as a means to establish more effective conservation and restoration of these important coastal habitats around the world.

Linking Ecosystem Services of Marine Protected Areas to Benefits in Human Wellbeing

This chapter examines the potential relationship between ecosystem services provided by coastal ecosystems and the design and management of Marine Protected Areas (MPAs). While all coastal and marine habitats provide a range of ecosystem services, the implementation and management of an MPA may result in improvements in the quality or supply of an ecosystem service as pressures upon protected features are minimised. This chapter focuses on the United Kingdom (UK) and examines the contrasting approaches to MPA designation applied in England, Scotland, Wales and Northern Ireland. We argue that MPAs are able to influence ecosystem services and this is dependent on design concepts such as the scale of the site, the listed features, and management measures. Understanding the portfolio of services derived from features within MPAs will improve planning and management, particularly in the context of making site specific or regional trade-offs over designation, or in understanding the benefits and impacts of setting conservation objectives and introducing measures to achieve them.

Fractal measures of spatial pattern as a heuristic for return rate in vegetative systems

Measurement of population persistence is a long-standing problem in ecology; in particular, whether it is possible to gain insights into persistence without long time-series. Fractal measurements of spatial patterns, such as the Korcak exponent or boundary dimension, have been proposed as indicators of the persistence of underlying dynamics. Here we explore under what conditions a predictive relationship between fractal measures and persistence exists. We combine theoretical arguments with an aerial snapshot and time series from a long-term study of seagrass. For this form of vegetative growth, we find that the expected relationship between the Korcak exponent and persistence is evident at survey sites where the population return rate can be measured. This highlights a limitation of the use of power-law patch-size distributions and other indicators based on spatial snapshots. Moreover, our numeric simulations show that for a single species and a range of environmental conditions that the Korcak–persistence relationship provides a link between temporal dynamics and spatial pattern; however, this relationship is specific to demographic factors, so we cannot use this methodology to compare between species.

Seagrass Dynamics and Resilience

The vulnerability of seagrass ecosystems, and the services they provide, to damage and loss from anthropogenic stressors has led to a surge of interest in understanding their resilience. This chapter examines patterns of change in tropical and temperate Australian seagrasses to identify underlying causes of the observed patterns. It then relates seagrass dynamics to ecosystem resilience, and examines how resilience can be measured, managed and enhanced. Seagrasses in tropical waters show strong seasonal patterns in many places, with seagrass extent and cover increasing during the winter dry season and decreasing during the summer wet season. This seasonality is overlaid by a striking longer term trend of increase during El Nino periods and subsequent loss during wetter, stormier La Nina periods. Seasonality is less evident in temperate waters, where mapping of dynamics has generally been used to show longer term patterns, especially large-scale loss after decades of stability, sometimes with partial recovery. Changes in some places have been linear and in others strongly non-linear, possibly indicative of systems breaching a threshold or tipping point in levels of stressors such as pollutants. Resilience theory has become a powerful tool for understanding the dynamics of seagrass change. Seagrass resilience requires several key traits: genetic and species diversity, good water quality, connected ecosystems and continuous habitats, and balanced trophic interactions. These traits are integrated through ecological feedbacks. In Zostera muelleri meadows, for example, the capacity for seagrass to resist decline during pulses of poor water quality depends on its ability to: (1) efficiently remove excessive nutrients from the water, thereby limiting phytoplankton growth and improving water clarity, (2) suppress resuspension of sediment for improved water clarity, and (3) provide habitat for grazing animals that remove epiphytic algae. The increased understanding of resilience is shifting the focus of seagrass ecosystem management towards the management of stressors to optimise key feedbacks, and thus ultimately to enhance resilience. The chapter culminates in descriptions of practical management actions demonstrated to effectively enhance key traits and overall seagrass resilience.

Growth effects of shading and sedimentation in two tropical seagrass species: Implications for port management and impact assessment

Seagrass meadows in many parts of the globe are threatened by a range of processes including port development, dredging and land clearing in coastal catchments, which can reduce water clarity and increase sedimentation pressure. As rates of seagrass loss increase, there is an urgent need to understand the potential impacts of development on these critical species. This research compares the effects of shading and burial by fine sand on two seagrass species Zostera muelleri and Halophila ovalis in Port Curtis Bay, an industrial harbour located on the continental margin adjacent to the Great Barrier Reef Heritage Area, Australia. The research finds that shading in combination with burial causes a significant decline in growth rates in both species, but that burial ≥10mm reduces growth rates to a greater extent than shading. The paper concludes by discussing the implications of these findings for port management and impact assessment.

Decline and Restoration Ecology of Australian Seagrasses

Since the first version of this book almost 30 years ago, significant losses of seagrass meadows have continued to be reported from around Australia as a result of natural and human induced perturbations. Conservative estimates indicate losses over the past two decades have more than doubled that estimated in the late 1990s. Conservation and mitigation of disturbance regimes have typically been the first line of defence, but ecological restoration or intervention is becoming increasingly necessary in a rapidly changing environment, and is potentially a more effective management strategy where seagrass habitat is already lost or heavily degraded. Accordingly, there has been an increase in the number of restoration studies and projects feeding our knowledge-base of restoration practice across Australia. Yet despite this increase, successful restoration has been rare, often uncoordinated, and almost always at a scale that is orders of magnitude lower than the scale of loss. Clearly, our understanding of the ecological mechanisms underlying successful and unsuccessful seagrass restoration is not keeping pace with the rates of loss and societal needs for restoration. Indeed, many orders of magnitude more restoration effort, in terms of science and practice and their interactions, will be required to prevent further seagrass loss. The science of seagrass restoration or restoration ecology is still a young science, but has strong foundations built from several decades of ecological research addressing many aspects of ecological interactions in seagrasses. While restoration has strong scientific underpinnings from ecological theory, it is clear that restoration ecology can also contribute to ecological theory by providing new and novel opportunities to advance our understanding of the mechanisms that promote functional ecosystems. In this chapter, we provide examples of this understanding across the levels of biological hierarchy, from genes to landscapes, and where possible include future strategic research directions.

Assessing spatial variation of seagrass habitat structure in New Caledonia: an integrated approach

Natural habitats can be described using an array of variables, but metrics that distil these multiple parameters into a single readily comparable value (e.g. a score) can prove useful for spatio-temporal comparisons as well as decisions concerning environmental resource management. In the lagoon of south-western New Caledonia, multiple habitat variables sampled from seagrass meadows were integrated into a single score for comparison of habitat structure across two spatial scales. Collectively, seagrass meadows scored at 69/100, indicating a ‘fair-to-good’ habitat structure. Spatial variation was evident, however, being greatest at the scale of ‘site’ (0.5–5 km) relative to ‘location’ (tens of kilometres). Key metrics of seagrass area, percentage cover and species identity appeared to drive spatial patterns in habitat structure scores. Although the causes of observed site-scale variation in seagrass structure are untested, differences in wave exposure among sites appear a likely contributing factor. Overall, integrated sampling techniques such as that used herein can provide a convenient way to rapidly compare seagrass habitats, and could be useful as early warning indicators of habitat change in regions where anthropogenic impacts that cause seagrass decline (e.g. eutrophication, sediment released from mining) are of concern.