Jimena Samper-Villarreal

Anticipative management for coral reef ecosystem services in the 21st century

Under projections of global climate change and other stressors, significant changes in the ecology, structure and function of coral reefs are predicted. Current management strategies tend to look to the past to set goals, focusing on halting declines and restoring baseline conditions. Here, we explore a complementary approach to decision making that is based on the anticipation of future changes in ecosystem state, function and services. Reviewing the existing literature and utilizing a scenario planning approach, we explore how the structure of coral reef communities might change in the future in response to global climate change and overfishing. We incorporate uncertainties in our predictions by considering heterogeneity in reef types in relation to structural complexity and primary productivity. We examine 14 ecosystem services provided by reefs, and rate their sensitivity to a range of future scenarios and management options. Our predictions suggest that the efficacy of management is highly dependent on biophysical characteristics and reef state. Reserves are currently widely used and are predicted to remain effective for reefs with high structural complexity. However, when complexity is lost, maximizing service provision requires a broader portfolio of management approaches, including the provision of artificial complexity, coral restoration, fish aggregation devices and herbivore management. Increased use of such management tools will require capacity building and technique refinement and we therefore conclude that diversification of our management toolbox should be considered urgently to prepare for the challenges of managing reefs into the 21st century.

Caribbean-wide, long-term study of seagrass beds reveals local variations, shifts in community structure and occasional collapse.

The CARICOMP monitoring network gathered standardized data from 52 seagrass sampling stations at 22 sites (mostly Thalassia testudinum-dominated beds in reef systems) across the Wider Caribbean twice a year over the period 1993 to 2007 (and in some cases up to 2012). Wide variations in community total biomass (285 to >2000 g dry m−2) and annual foliar productivity of the dominant seagrass T. testudinum (<200 and >2000 g dry m−2) were found among sites. Solar-cycle related intra-annual variations in T. testudinum leaf productivity were detected at latitudes > 16°N. Hurricanes had little to no long-term effects on these well-developed seagrass communities, except for 1 station, where the vegetation was lost by burial below ∼1 m sand. At two sites (5 stations), the seagrass beds collapsed due to excessive grazing by turtles or sea-urchins (the latter in combination with human impact and storms). The low-cost methods of this regional-scale monitoring program were sufficient to detect long-term shifts in the communities, and fifteen (43%) out of 35 long-term monitoring stations (at 17 sites) showed trends in seagrass communities consistent with expected changes under environmental deterioration.

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.

Seagrass ecosystem trajectory depends on the relative timescales of resistance, recovery and disturbance

Seagrass ecosystems are inherently dynamic, responding to environmental change across a range of scales. Habitat requirements of seagrass are well defined, but less is known about their ability to resist disturbance. Specific means of recovery after loss are particularly difficult to quantify. Here we assess the resistance and recovery capacity of 12 seagrass genera. We document four classic trajectories of degradation and recovery for seagrass ecosystems, illustrated with examples from around the world. Recovery can be rapid once conditions improve, but seagrass absence at landscape scales may persist for many decades, perpetuated by feedbacks and/or lack of seed or plant propagules to initiate recovery. It can be difficult to distinguish between slow recovery, recalcitrant degradation, and the need for a window of opportunity to trigger recovery. We propose a framework synthesizing how the spatial and temporal scales of both disturbance and seagrass response affect ecosystem trajectory and hence resilience.

Spatial and temporal variability of seagrass at Lizard Island, Great Barrier Reef

Abstract Increasing threats to natural ecosystems from local and global stressors are reinforcing the need for baseline data on the distribution and abundance of organisms. We quantified spatial and/or temporal patterns of seagrass distribution, shoot density, leaf area index, biomass, productivity, and sediment carbon content in shallow water (0–5 m) at Lizard Island, Great Barrier Reef, Australia, in field surveys conducted in December 2011 and October 2012. Seagrass meadows were mapped using satellite imagery and field validation. A total of 18.3 ha of seagrass, composed primarily of Thalassia hemprichii and Halodule uninervis, was mapped in shallow water. This was 46% less than the area of seagrass in the same region reported in 1995, although variations in mapping methods may have influenced the magnitude of change detected. There was inter-annual variability in shoot density and length, with values for both higher in 2011 than in 2012. Seagrass properties and sediment carbon content were representative of shallow-water seagrass meadows on a mid-shelf Great Barrier Reef island. The data can be used to evaluate change, to parameterize models of the impact of anthropogenic or environmental variability on seagrass distribution and abundance, and to assess the success of management actions.

Habitat characteristics provide insights of carbon storage in seagrass meadows

Seagrass meadows provide multiple ecosystem services, yet they are among the most threatened ecosystems on earth. Because of their role as carbon sinks, protection and restoration of seagrass meadows contribute to climate change mitigation. Blue Carbon strategies aim to enhance CO2 sequestration and avoid greenhouse gasses emissions through the management of coastal vegetated ecosystems, including seagrass meadows. The implementation of Blue Carbon strategies requires a good understanding of the habitat characteristics that influence Corg sequestration. Here, we review the existing knowledge on Blue Carbon research in seagrass meadows to identify the key habitat characteristics that influence Corg sequestration in seagrass meadows, those factors that threaten this function and those with unclear effects. We demonstrate that not all seagrass habitats have the same potential, identify research priorities and describe the implications of the results found for the implementation and development of efficient Blue Carbon strategies based on seagrass meadows.

Multi-temporal mapping of seagrass cover, species and biomass of the Eastern Banks, Moreton Bay, Australia, with links to shapefiles.

Multi-temporal mapping of seagrass cover, species and biomass of the Eastern Banks, Moreton Bay, Australia, with links to shapefiles.

Seagrass Organic Carbon Stocks Show Minimal Variation Over Short Time Scales in a Heterogeneous Subtropical Seascape

Blue carbon initiatives require accurate monitoring of carbon stocks. We examined sources of variability in seagrass organic carbon (Corg) stocks, contrasting spatial with short temporal scales. Seagrass morphology and sediment Corg stocks were measured from biomass and shallow sediment cores collected in Moreton Bay, Australia. Samples were collected between 2012 and 2013, from a total of 77 sites that spanned a gradient of water turbidity. Environmental measures of water quality between 2000 and 2013 revealed strong seasonal fluctuations from summer to winter, yet seagrass biomass exhibited no temporal variation. There was no temporal variability in Corg stocks, other than below ground biomass stocks were slightly higher in June 2013. Seagrass locations were grouped into riverine, coastal, and seagrass loss locations and short temporal variability of Corg stocks was analysed within these categories to provide clearer insights into temporal patterns. Above ground Corg stocks were similar between coastal and riverine meadows. Below ground Corg stocks were highest in coastal meadows, followed by riverine meadows. Sediment Corg stocks within riverine meadows were much higher than at coastal meadows and areas of seagrass loss, with no difference in sediment Corg stocks between these last two categories. Riverine seagrass meadows, of higher turbidity, had greater total Corg stocks than meadows in offshore areas irrespective of time. We suggest that Corg stock assessment should prioritise sampling over spatial gradients, but repeated monitoring over short time scales is less likely to be warranted if environmental conditions remain stable.

Community Perception and processes of Integrated Coastal Zone Management in the North Pacific of Costa Rica.

Las tendencias en la percepcion sobre el uso y manejo de los recursos marino-costeros en el Pacifico Norte de Costa Rica se investigaron a traves de talleres de consulta en las comunidades de Cuajiniquil, Villarreal, Montezuma y zonas aledanas. En total 112 personas provenientes de ocho comunidades asistieron a la convocatoria. En general se registro una mayor participacion de hombres que de mujeres. Los principales recursos marinos identificados fueron los pesqueros y el de playa/olas; las actividades destacadas, la pesca y el turismo. Se asigno a Incopesca una deficiente participacion en la administracion de los recursos y se otorgo una baja participacion a los sectores de pesca artesanal y turismo. Fue destacada la participacion de lideresas en Montezuma, lo que planteo la necesidad de fomentar la autonomia de la mujer costena para que mas ciudadanas esten en condiciones de contribuir en la toma de decisiones como un actor legitimo. Los principales retos detectados fueron la pesca ilegal en las Areas Marinas Protegidas y la sobreexplotacion pesquera. Como soluciones, las comunidades propusieron elementos de pesca sostenible, ademas de la eliminacion de la pesca de arrastre y de buceo con compresor. El proceso de consulta revela la necesidad de proponer alternativas economicas a la pesca, educar a las comunidades, enfocar la atencion en categorias de manejo que no prohiban la pesca artesanal y promover la participacion de la sociedad civil en la toma de decisiones. Se recomienda aprovechar los mecanismos ya existentes para la inclusion de la sociedad civil y de implementarse procesos participativos, que estos velen por el interes publico del pais aunque el proyecto sea de caracter local. Se evidencia que la gobernanza marina del Pacifico Norte del pais enfrenta retos, entre ellos la falta de una gestion participativa de los recursos marino-costeros, pero a su vez cuenta con propuestas ciudadanas concretas que podrian contribuir con una toma de decisiones mas representativa de los distintos intereses de la region.

Seagrass Resistance to Light Deprivation: Implications for Resilience

Seagrass habitat is strongly constrained by light availability. Decline in benthic light due to anthropogenic activities (e.g. eutrophication, dredging and catchment modification) is a major threat to seagrass ecosystems, both within Australia and internationally. Even in pristine conditions, light available to seagrasses can be highly variable on timescales ranging from seconds to years. This chapter outlines the three primary mechanisms which enable seagrass to adapt to and/or resist temporary light deprivation: (1) consumption of accumulated carbon; (2) reduction in rates of growth and carbon loss; and (3) increased efficiency of radiation capture and usage. The capacity to withstand severe light deprivation ranges from only two weeks for small, colonising seagrass species such as Halophila ovalis , to beyond two years for large, persistent species such as Posidonia sinuosa. This “tolerance time” depends on the magnitude and timing of the light deprivation, current environmental conditions (e.g. temperature and sediment sulphides) as well as preceding conditions. This chapter proposes a simple conceptual model for seagrass resilience to temporary light reduction , combining both resistance (the capacity of seagrass to survive the light deprivation event), and the capacity to recover once the disturbance ends. Data is synthesized for several potential indicators of seagrass resistance to light reduction.