Globally increasing sea surface temperatures threaten coral reefs, both directly and through interactions with local stressors. More resilient reefs have a higher likelihood of returning to a coral-dominated state following a disturbance, such as a mass bleaching event. To advance practical approaches to reef resilience assessments and aid resilience-based management of coral reefs, we conducted a resilience assessment for Puerto Rico’s coral reefs, modified from methods used in other U.S. jurisdictions. We calculated relative resilience scores for 103 sites from an existing commonwealth-wide survey using eight resilience indicators—such as coral diversity, macroalgae percent cover, and herbivorous fish biomass—and assessed which indicators most drove resilience. We found that sites of very different relative resilience were generally highly spatially intermixed, underscoring the importance and necessity of decision making and management at fine scales. In combination with information on levels of two localized stressors (fishing pressure and pollution exposure), we used the resilience indicators to assess which of seven potential management actions could be used at each site to maintain or improve resilience. Fishery management was the management action that applied to the most sites. Furthermore, we combined sites’ resilience scores with projected ocean warming to assign sites to vulnerability categories. Island-wide or community-level managers can use the actions and vulnerability information as a starting point for resilience-based management of their reefs. This assessment differs from many previous ones because we tested how much information could be yielded by a “desktop” assessment using freely-available, existing data rather than from a customized, resilience-focused field survey. The available data still permitted analyses comparable to previous assessments, demonstrating that desktop resilience assessments can substitute for assessments with field components under some circumstances.
Incorporating coastal ecosystems in climate adaptation planning is needed to maintain the well-being of both natural and human systems. Our vulnerability study uses a multidisciplinary approach to evaluate climate change vulnerability of an urbanized coastal community that could serve as a model approach for communities worldwide, particularly in similar Mediterranean climates. We synthesize projected changes in climate, coastal erosion and flooding, watershed runoff and impacts to two important coastal ecosystems, sandy beaches and coastal salt marshes. Using downscaled climate models along with other regional models, we find that temperature, extreme heat events, and sea level are expected to increase in the future, along with more intense rainfall events, despite a negligible change in annual rainfall. Consequently, more droughts are expected but the magnitude of larger flood events will increase. Associated with the continuing rise of mean sea level, extreme coastal water levels will occur with increasingly greater magnitudes and frequency. Severe flooding will occur for both natural (wetlands, beaches) and built environments (airport, harbor, freeway, and residential areas). Adaptation actions can reduce the impact of rising sea level, which will cause losses of sandy beach zones and salt marsh habitats that support the highest biodiversity in these ecosystems, including regionally rare and endangered species, with substantial impacts occurring by 2050. Providing for inland transgression of coastal habitats, effective sediment management, reduced beach grooming and removal of shoreline armoring are adaptations that would help maintain coastal ecosystems and the beneficial services they provide.
This study examines the occurrence of humpback whale (Megaptera novaeangliae) song in the northeast Pacific from three years of continuous recordings off central California (36.713°N, 122.186°W). Song is prevalent in this feeding and migratory habitat, spanning nine months of the year (September–May), peaking in winter (November–January), and reaching a maximum of 86% temporal coverage (during November 2017). From the rise of song in fall through the end of peak occurrence in winter, song length increases significantly from month to month. The seasonal peak in song coincides with the seasonal trough in day length and sighting-based evidence of whales leaving Monterey Bay, consistent with seasonal migration. During the seasonal song peak, diel variation shows maximum occurrence at night (69% of the time), decreasing during dawn and dusk (52%), and further decreasing with increasing solar elevation during the day, reaching a minimum near solar noon (30%). Song occurrence increased 44% and 55% between successive years. Sighting data within the acoustic detection range of the hydrophone indicate that variation in local population density was an unlikely cause of this large interannual variation. Hydrographic data and modeling of acoustic transmission indicate that changes in neither habitat occupancy nor acoustic transmission were probable causes. Conversely, the positive interannual trend in song paralleled major ecosystem variations, including similarly large positive trends in wind-driven upwelling, primary productivity, and krill abundance. Further, the lowest song occurrence during the first year coincided with anomalously warm ocean temperatures and an extremely toxic harmful algal bloom that affected whales and other marine mammals in the region. These major ecosystem variations may have influenced the health and behavior of humpback whales during the study period.
Phosphate mining activities on Christmas Island began in the late 1800's providing a unique, long-term case study in which to assess the impacts of mining on coral reef development. Watershed modelling was used to identify potential “hotspots” of mining runoff on to adjacent reefs. Pollution hotspots were also confirmed by analysis of reef sediment. Phosphate rich mining runoff flowed from local watersheds onto nearshore coral reefs with levels of up to 54,000 mg/kg of total phosphate recorded in reef sediment at the Dryers reef site adjacent to the main phosphate storage facility. Using this combination of watershed modelling and in-situ sediment contamination data we identified six coral reef sites along an environmental impact gradient. In-situ benthic transects were paired with a new rubble-encruster method enabling the analysis to combine large scale transect information alongside fine-scale data on epibenthic and encruster assemblages. Results demonstrate that phosphate rich sediment loading negatively impacted coral reef building communities, in particular, branching corals and calcareous encrusting organisms, critical to the future survival of coral reef ecosystems. These findings highlight the importance of curtailing runoff and pollution from catchment based mining activities and protecting reefs for the future.
Coastal habitats (e.g., seagrass beds, shallow mud, and sand flats) strongly influence survival, growth, and reproduction of marine fish and invertebrate species. Many of these species have declined over the past decades, coincident with widespread degradation of coastal habitats, such that an urgent need exists to model the quantitative value of coastal habitats to their population dynamics. For exploited species, demand for habitat considerations will increase as fisheries management contends with habitat issues in stock assessments and management in general moves toward a more ecosystem-based approach. The modeling of habitat function has, to date, been done on a case-by-case basis involving diverse approaches and types of population models, which has made it difficult to generalize about methods for incorporating habitat into population models. In this review, we offer guiding concepts for how habitat effects can be incorporated in population models commonly used to simulate the population dynamics of fish and invertebrate species. Many marine species share a similar life-history strategy as long-lived adults with indeterminate growth, high fecundity, a planktonic larval form, and benthic juveniles and adults using coastal habitats. This suite of life-history traits unites the marine species across the case studies, such that the population models can be adapted for other marine species. We categorize population models based on whether they are static or dynamic representations of population status, and for dynamic, further into unstructured, age/size class structured, and individual-based. We then use examples, with an emphasis on exploited species, to illustrate how habitat has been incorporated, implicitly (correlative) and explicitly (mechanistically), into each of these categories. We describe the methods used and provide details on their implementation and utility to facilitate adaptation of the approaches for other species and systems. We anticipate that our review can serve as a stimulus for more widespread use of population models to quantify the value of coastal habitats, so that their importance can be accurately realized and to facilitate cross-species and cross-system comparisons. Quantitative evaluation of habitat effects in population dynamics will increasingly be needed for traditional stock assessments, ecosystem-based management, conservation of at-risk habitats, and recovery of overexploited stocks that rely on critical coastal habitats during their life cycle.
The coastal and marine environment provides a wide range of ecosystem services, many of which may be impacted through coastal management. Incorporating these values into cost-benefit analysis to support decision making is hampered by the lack of existing appropriate measures. While studies can be undertaken by these agencies to collect the appropriate values, the number of different habitats that may need to be considered is greater than what could reasonably be included in traditional economic approaches. In this paper, we propose combining of a multi-criteria method, namely the Analytic Hierarchy Process (AHP), with choice experiments to develop estimates for a wide range of coastal and marine habitat values that can be used by local planners and coastal managers. We apply the approach to the coastal regions in New South Wales (NSW), Australia. Coastal residents were initially asked to express their preferences for protecting different coastal and marine habitats using AHP, from which a relative index of utility was derived. A choice experiment was also implemented, involving a hypothetical new coastal reserve in their area protecting different combinations of habitats and funded through an increase in their local council rates. We found that nearly 90 per cent of NSW coastal residents were willing to pay to support coastal protection. Relative values derived from the AHP were used to extrapolate the choice experiment results to provide estimates of non-market values for a wide range of coastal and marine habitats.
The assessment of eutrophic conditions is a formal requirement of several European Directives. Typically, these eutrophication assessments use a set of primary indicators which include dissolved inorganic nutrients, chlorophyll, dissolved oxygen and secondary information such as phytoplankton community data. Each directive is characterized by a different geographical or political boundary which defines the area under assessment. Several disparate sources of data from the Thames estuary and Liverpool Bay in the United Kingdom collected from different monitoring programs were combined to generate a fully integrated dataset. Data sources included remote sensing, ecosystem models, moorings, freshwater inputs and traditional ship surveys. Different methods were explored for assigning ecologically relevant assessment areas including delineation of the assessment area based on salinity, extent of the river plume influence and ecohydrodynamic characteristics in addition to the traditional geographically defined typologies associated with the different directives. Individual eutrophication indicators were tested across these revised typologies for the period 2006–2015, and outcomes of the different metrics were compared across the river to marine continuum for the two UK areas. There have been statistically significant decreasing trends in the loads of ammonium, nitrite and dissolved inorganic phosphorous between 1994 and 2016 in both the Thames estuary and Liverpool Bay study areas but no statistically significant trends in loads of nitrate or dissolved inorganic nitrogen. There have been statistically significant increases in riverine nitrogen:phosphorous between 1994 and 2016. Nutrient concentrations exceeded assessment thresholds across nearly all areas other than the large offshore assessment areas, and outcomes of the chlorophyll metric were often below assessment thresholds in the estuarine-based areas and the offshore areas, but exceedances of thresholds occurred in the near coastal areas. However, trait-based indicators of phytoplankton community using functional groups show changes in plankton community structure over the assessment period, indicating that additional metrics that quantify community shifts could be a useful measurement to include in future eutrophication assessments.
Coastal waters provide a wide range of ecosystem services (ES), but are under intensive human use, face fast degradation and are subject to increasing pressures and changes in near future. As consequence, European Union (EU) water policies try to protect, restore and manage coastal and marine systems in a sustainable way. The most important EU directive in this respect is the Water Framework Directive (WFD) (2000/60/EC). Objective is to reach a “good status” in EU waters, following a stepwise and guided process. Our major objective is to test how an ecosystem service assessment can support WFD implementation in practice. We use the Marine Ecosystem Service Assessment Tool (MESAT) that utilizes spatial definitions, reference conditions and the good status according to the WFD as well as data and information gained during the implementation process. The data-based tool allows comparative analyses between different ecological states and an evaluation of relative changes in ES provision. We apply MESAT to two contrasting systems in the German Baltic Sea region, the rural Schlei and the urban/industrialized Warnow Estuary. These data-based assessments show how the ES provision has changed between the historic, pre-industrial state around 1880 (reference conditions with high ecological status), the situation around 1960 (good ecological status), and today. The analysis separates the estuaries into water bodies. A complementary expert-based ES assessment compares the situation today with a future scenario “Warnow 2040” assuming a good ecological status as consequence of a successful WFD implementation. Strengths and weaknesses of the approaches and their utilization in the WFD are discussed. ES assessments can be regarded as suitable to support public relation activities and to increase the acceptance of measures. Further, they are promising tools in participation and stakeholder processes within the planning of measures. However an ES assessment not only supports the WFD implementation, but the WFD provides a frame for ES assessments larger scale assessments in seascapes, increases the acceptance of the ES approach and the readiness of stakeholders to get involved.
Healthy river ecosystems can provide fundamental ecological services for human survival and social development. However, previous studies that have sought to assess river ecosystem health have primarily focused on individual biological communities rather than on all aquatic communities and have been based on a single-index assessment method, thereby leading to large uncertainties in the results. In this study, we developed a new framework for the integrated assessment of aquatic ecosystem health based on the principal communities of fish, zoobenthos, phytoplankton, and zooplankton in rivers. An index of biotic integrity was used to evaluate the health of fish and zoobenthos communities, and a diversity index was used to evaluate the health of zooplankton and phytoplankton communities. To integrate the health assessment results from these four communities, a quantile normalization method was developed, where uncertainties in assessments obtained using the diversity index were well compensated for by the assessments obtained using the biotic integrity index. The framework was then applied to a pilot city, which is being constructed as a civilized freshwater ecological city in China. The results were then compared with those previously obtained based on the single-community method. Using this new framework, we found that the aquatic ecosystem health changed regularly in space and over time. Large differences were detected among the assessments of the four individual communities based on the single-community method, with the health score determined using phytoplankton being the highest, followed by that of zoobenthos, zooplankton, and fish, which made it difficult to reach a definitive conclusion regarding aquatic health status. The integrated assessment framework presented in this study successfully overcame the narrow perspective of the single-community method, thereby reducing uncertainties in the assessments based only on a single diversity index, and instead provides a comprehensive view of the status of aquatic ecosystem health. Thus, this integrated framework could assist river managers and stakeholders in developing comprehensive strategies for ecological restoration and water resource management and could become a key research tool for the health assessment and rehabilitation of aquatic ecosystems globally.