Non-Linearity in Ecosystem Services: Temporal and Spatial Variability in Coastal Protection

Natural processes tend to vary over time and space, as well as between species. The ecosystem services these natural processes provide are therefore also highly variable. It is often assumed that ecosystem services are provided linearly (unvaryingly, at a steady rate), but natural processes are characterized by thresholds and limiting functions. In this paper, we describe the variability observed in wave attenuation provided by marshes, mangroves, seagrasses, and coral reefs and therefore also in coastal protection. We calculate the economic consequences of assuming coastal protection to be linear. We suggest that, in order to refine ecosystem-based management practices, it is essential that natural variability and cumulative effects be considered in the valuation of ecosystem services

Attached Bacterial Populations Shared by Four Species of Aquatic Angiosperms▿

Symbiotic relationships between microbes and plants are common and well studied in terrestrial ecosystems, but little is known about such relationships in aquatic environments. We compared the phylogenetic diversities of leaf- and root-attached bacteria from four species of aquatic angiosperms using denaturing gradient gel electrophoresis (DGGE) and DNA sequencing of PCR-amplified 16S rRNA genes. Plants were collected from three beds in Chesapeake Bay at sites characterized as freshwater (Vallisneria americana), brackish (Potomogeton perfoliatus and Stuckenia pectinata), and marine (Zostera marina). DGGE analyses showed that bacterial communities were very similar for replicate samples of leaves from canopy-forming plants S. pectinata and P. perfoliatus and less similar for replicate samples of leaves from meadow-forming plants Z. marina and V. americana and of roots of all species. In contrast, bacterial communities differed greatly among plant species and between leaves and roots. DNA sequencing identified 154 bacterial phylotypes, most of which were restricted to single plant species. However, 12 phylotypes were found on more than one plant species, and several of these phylotypes were abundant in clone libraries and represented the darkest bands in DGGE banding patterns. Root-attached phylotypes included relatives of sulfur-oxidizing Gammaproteobacteria and sulfate-reducing Deltaproteobacteria. Leaf-attached phylotypes included relatives of polymer-degrading Bacteroidetes and phototrophic Alphaproteobacteria. Also, leaves and roots of three plant species hosted relatives of methylotrophic Betaproteobacteria belonging to the family Methylophilaceae. These results suggest that aquatic angiosperms host specialized communities of bacteria on their surfaces, including several broadly distributed and potentially mutualistic bacterial populations

Correction: Seagrass Ecosystem Services and Their Variability across Genera and Geographical Regions.

[This corrects the article DOI: 10.1371/journal.pone.0163091.]

SeagrassNet monitoring across the Americas: case studies of seagrass decline

Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land–sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world\u27s oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1–2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action

Perceived provision of seagrass ecosystem services.

<p>Global A) mean frequency, B) mean frequency per genus, of perceived provision of different ecosystem services of seagrasses. The higher mean the more frequently that service is provided. Data are across bioregion and genera means ± SE. Horizontal bars represent homogenous subsets (Tukey test).</p

Seagrass meadow exposed during low tide.

<p>Patchy seagrass meadow dominated by <i>Thalassodendron ciliatum</i> during low tide in Zanzibar, Tanzania. Photo credit: Lina Mtwana Nordlund.</p

Ecosystem services (ES) provided by seagrass—expert eliciting.

<p>Colours represent consensus view of experts’ in each bioregional group. Red represents service not present; grey unknown and green service present. A sum of present, unknown, not present services scores can be seen in the table to the far right per ES and at the bottom for each genus in every bioregion. Bioregions according to Short et al., 2007 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163091#pone.0163091.ref002" target="_blank">2</a>]:I = Temperate North Atlantic, II = Tropical Atlantic, III = Mediterranean, IV = Temperate North Pacific, V = Tropical Indo-Pacific, VI = Temperate Southern Oceans. At the far left # indicates a number that corresponds to the same ecosystem service in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163091#pone.0163091.t001" target="_blank">Table 1</a> facilitate comparisons, and has no prioritization.</p