Ecological Baseline Research Articles

Reconstruction of Atlantic herring (Clupea harengus) recruitment in the North Sea for the past 455 years based on the δ13C from annual shell increments of the ocean quahog (Arctica islandica)

AbstractUnderstanding the recruitment variability of the Atlantic herring North Sea stock remains a key objective of stock assessment and management. Although many efforts have been undertaken linking climatic and stock dynamic factors to herring recruitment, no major attempt has been made to estimate recruitment levels before the 20th century. Here, we present a novel annually resolved, absolutely dated herring recruitment reconstruction, derived from stable carbon isotope geochemistry (δ13C), from ocean quahog shells from the Fladen Ground (northern North Sea). Our age model is based on a growth increment chronology obtained from fourteen shells. Ten of these were micromilled at annual resolution for δ13C analysis. Our results indicate that the anthropogenically driven relative depletion of 13C, the oceanic Suess effect (oSE), became evident in the northern North Sea in the 1850s. We calculated a regression line between the oSE‐detrended δ13C results (δ13CṠ) and diatom abundance in the North Sea, the regression being mediated by the effect of phytoplankton on the δ13C of the ambient dissolved inorganic carbon. We used this regression to build an equation mediated by a nutritional link to reconstruct herring recruitment using δ13CṠ. The reconstruction suggests that there were five extended episodes of low‐recruitment levels before the 20th century. These results are supported by measured recruitment estimates and historical fish catch and export documentation. This work demonstrates that molluscan sclerochronological records can contribute to the investigation of ecological baselines and ecosystem functioning impacted by anthropogenic activity with implications for conservation and stock management.

TRACING ORIGIN AND COLLAPSE OF HOLOCENE BENTHIC BASELINE COMMUNITIES IN THE NORTHERN ADRIATIC SEA

The shallow northern Adriatic Sea has a long history of anthropogenic impacts that reaches back many centuries. While the effects of eutrophication, overfishing, pollution, and trawling over recent decades have been extensively studied, the major ecological turnovers during the Holocene as a whole remain poorly explored. In this study, we reconstruct ecological baselines defining benthic ecosystem composition prior to major anthropogenic changes at four stations characterized by low sedimentation and millennial-scale time averaging of molluscan assemblages. We discriminate between natural and anthropogenic drivers based on (1) stratigraphic changes in the composition of molluscan communities observed in sediment cores and (2) changes in concentrations of heavy metals, pollutants, and organic enrichment. The four 1.5-m long sediment cores reach back to the Pleistocene–Holocene boundary, allowing for a stratigraphic distinction of the major sea-level phases of the Holocene. During the transgressive phase and maximum flooding, sea-level and establishment of the modern circulation pattern determined the development of benthic communities in shallow-water, vegetated habitats with epifaunal biostromes and, in deeper waters, with bryozoan meadows. After sea-level stabilization, the composition of these baseline communities remained relatively uniform and started to change markedly only with the intensification of human impacts in the late highstand, leading to a dominance of infauna and a decline of epifauna at all sites. This profound ecological change reduced species richness, increased the abundance of infaunal suspension feeders, and led to a decline of grazers and deposit feeders. We suggest that modern soft-bottom benthic communities in the northern Adriatic Sea today do not show the high geographic heterogeneity in composition characteristic of benthos prior to anthropogenic influences.

ESA Historical Records Committee Newsletter January 2019

ESA Historical Records Committee Newsletter January 2019

Report of the workshop Evaluating the nature of midwater mining plumes and their potential effects on midwater ecosystems

Report of the workshop Evaluating the nature of midwater mining plumes and their potential effects on midwater ecosystems

Parks for sharks: human exclusion areas outperform no‐take marine reserves

We collected reef shark population data from a large network of no‐take and no‐entry reserves (ie human exclusion areas), as well as from fished reefs, in one of the world's most intensively managed marine parks – the Great Barrier Reef of Australia. The sampled reserves have been protected for varying lengths of time, making it possible to use space‐for‐time chronosequences to infer recovery trajectories of reef shark populations after extractive use is banned, and to compare the effectiveness of shark population recovery in no‐take and no‐entry reserves. After 20–40 years of protection, density and biomass of sharks in no‐entry reserves approached asymptotes (ie plateaus) that were more than double and triple, respectively, those in no‐take reserves. These results not only indicate that restoration of near‐natural shark populations requires multidecadal time frames, but also clearly demonstrate the superior performance of no‐entry reserves in terms of rebuilding shark populations. Ongoing poaching in no‐take reserves, which are more difficult for law enforcement to police than no‐entry reserves, is the probable cause of the disparity. Given the ubiquitous use of no‐take reserves as ecological baselines and the potentially pervasive trophic effects of removing large predators, we argue that current perceptions of the structure and function of natural reef ecosystems may be skewed, which has broad implications for science and management of marine ecosystems

Whale Shark Tourism: Impacts on Coral Reefs in the Philippines.

Reef-based tourism has been developing rapidly in recent decades yet its impacts on reef ecosystems are often overlooked. In Tan-awan, Oslob, Philippines, whale sharks are attracted to the shallow reefs where they are provisioned up to 50 tons y-1 of feed and this phenomenon in turn attracts >300,000 y-1 visitors. Given the intensive provisioning and concentrating tourism activities, we hypothesized that the whale shark tourism-impacted site (IS) will have greater impacts on reef degradation and higher anthropogenic nitrogen pollution level compared to its reference site (RS). Ecological surveys revealed that relative to the RS, the IS had 36% higher relative abundance of Pocillopora and Porites coral over other genera, >2.5-fold lower coral density, and 20% higher macroalgal cover, which we concluded are signs of reef degradation. Also, we conducted stable nitrogen isotope analysis on gorgonian skeletons to trace nitrogen sources at both sites through time. Although an average 1‰ isotope enrichment found in the IS relative to the RS could indicate anthropogenic nitrogen inputs in the IS, this enrichment was consistent over time and existed before the tourism developed. Despite that, we cautioned against the imminent threat of local eutrophication caused by the continued inputs of nitrogen derived from provisioning and tourism activities. In summary, this study provided the first documentation of the impacts of provisioned whale shark tourism on the local reefs in Tan-awan and established an ecological baseline for future comparisons. Such assessments can offer important information on reef health, coastal development, and tourism management.

Long-term trends in the foraging ecology and habitat use of an endangered species: an isotopic perspective.

Evaluating long-term drivers of foraging ecology and population productivity is crucial for providing ecological baselines and forecasting species responses to future environmental conditions. Here, we examine the trophic ecology and habitat use of North Atlantic leatherback turtles (St. Croix nesting population) and investigate the effects of large-scale oceanographic conditions on leatherback foraging dynamics. We used bulk and compound-specific nitrogen isotope analysis of amino acids (CSIA-AA) to estimate leatherback trophic position (TP) over an 18-year period, compare these estimates with TP estimates from a Pacific leatherback population, and elucidate the pre-nesting habitat use patterns of leatherbacks. Our secondary objective was to use oceanographic indices and nesting information from St. Croix leatherbacks to evaluate relationships between trophic ecology, nesting parameters, and regional environmental conditions measured by the North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation. We found no change in leatherback TP over time and no difference in TP between Atlantic and Pacific leatherbacks, indicating that differences in trophic ecology between populations are an unlikely driver of the population dichotomy between Pacific and Atlantic leatherbacks. Isotope data suggested that St. Croix leatherbacks inhabit multiple oceanic regions prior to nesting, although, like their conspecifics in the Pacific, individuals exhibit fidelity to specific foraging regions. Leatherback nesting parameters were weakly related to the NAO, which may suggest that positive NAO phases benefit St. Croix leatherbacks, potentially through increases in resource availability in their foraging areas. Our data contribute to the understanding of leatherback turtle ecology and potential mechanistic drivers of the dichotomy between populations of this protected species.

Synthesis of Environmental Research Knowledge: The Case of Paraguayan Pantanal Tropical Wetlands

The Paraguayan Pantanal offers a valuable case of research regarding natural resource management in tropical wetlands. It is one of the world´s largest wetland of globally important ecological and cultural value that is threatened from environmental exploitations. Paradoxically, this area is rarely scientifically investigated. Therefore, in this paper, this case was chosen to identify literature indirectly related to the area and to highlight the dominant research trends and corresponding gaps. This research was conducted to cluster the available science-based research of Pantanal´s tropical wetlands in order to advocate for more environmental governance focus. Concepts used in the scientific literature of the Paraguayan Pantanal were extrapolated and summarized in category system. A cluster framework of 12 variables of community-based natural resource management (CBNRM) was classified into three main search-categories: community engagement and participatory approach (CEPA), natural resources management (NRM) and framework developed (FD). The frequency of different categories demonstrates the natural science´s perspectives dominate over human sciences and humanities. Most of the Paraguayan Pantanal has been studied with regard to its ecological, biological and physical properties. The development of research interest over time and the primary focus on ecological baseline conditions are related to its designation as a Ramsar Site, an UNESCO tentative World Heritage Site and the orientation of national policies towards either environmental protection or regional economic development. A substantial research gap was identified in the FD as studies tended to link their findings to human activities but disregarded the connection between governance variables, natural resource and environmental developments. It is suggested to expand the natural science´s perspective on Paraguay´s wetlands to account for economic, social and political aspects in order to develop a holistic and environmentally sustainable production of science in and about the area.

Wolves for Yellowstone: dynamics in time and space

The reintroduction of gray wolves (Canis lupus) to Yellowstone National Park is the most celebrated ecological experiment in history. As predicted by population models, the rapid recovery of a wolf population caused both temporal and spatial variability in wolf–ungulate interactions that likewise generated temporal and spatial variation in the expression of trophic cascades. This has amplified spatial variation in vegetation in Yellowstone, particularly with willow (Salix spp.) and cottonwood (Populus spp.) in riparian areas, with associated changes in food webs. Increasing influences of grizzly bears (Ursus arctos), cougars (Puma concolor), and bison (Bisonbison) are making what initially was predominantly an elk–wolf interaction into an increasingly complex system. Outside Yellowstone, however, humans have a dominant influence in western North America that overwhelms trophic cascades resulting in what appear to be bottom-up influences on community structure and function. Complex and unexpected ecosystem responses to wolf recovery in Yellowstone reinforce the value of national parks and other protected areas as ecological baseline reserves.

Complementarity of indigenous and western scientific approaches for monitoring forest state.

Cross-cultural environmental monitoring systems inform on a broad suite of indicators relevant to both scientific and local communities. In this study, we used forest-plot-based survey measures developed by western scientists and a set of community-based survey indicators developed by Māori, the indigenous people of New Zealand (NZ), to compare the current state of two ecologically congruent forests (Whirinaki and Ruatāhuna), as they related to a historic Ruatāhuna forest state (Baseline; 1955-1975) in NZ. Both the plot-based and community-based field surveys indicated that the Whirinaki forest was in a better state than the Ruatāhuna forest. This was supported by a stronger mauri (concept of life essence) rating assigned by Māori elders to the Whirinaki forest compared with the Ruatāhuna forests. However, both the Ruatāhuna and Whirinaki forests were deemed to be in a significantly poorer state than the Baseline forest. A cross-cultural monitoring system provides understanding of forest state that both managers and communities can use for decision-making. Historical baselines of forest state can provide ecological targets for restoration initiatives and also identify where on the restoration continuum current forest indicators lie. The alignment of plot-based measures with community-based indicators offers possibilities for future-proofing a cross-cultural monitoring system and buffering it from intergenerational shifts in ecological baselines. The opportunity for indigenous peoples and local communities to apply their traditional ways of knowing, and interpret and act on information they understand are crucial components of cross-cultural environmental management regimes.

Live-Dead Mismatch of Molluscan Assemblages Indicates Disturbance from Anthropogenic Eutrophication in the Barnegat Bay-Little Egg Harbor Estuary

Previous research combining data on the abundance of benthic invertebrates living in the northernmost section of the Barnegat Bay-Little Egg Harbor estuary with data on water quality suggested a community composition consistent with anthropogenic eutrophication. This part of the estuary, however, experiences both high-nutrient and low-salinity environmental conditions, which are both ecologically stressful to sensitive species and favorable to opportunistic species, complicating assessments of the direct effects of anthropogenic eutrophication. Here, geohistorical baselines were derived from molluscan death assemblages from four localities along a north-south gradient in the bay—two northern low-salinity, high-nutrient sites and two southern high-salinity, low-nutrient sites—to disentangle the effects of salinity and nutrient enrichment on the composition of benthic communities. Disturbance in the northern section of the estuary from freshwater input has been relatively consistent for thousands of years, but nutrient enrichment is a more recent stressor, developing only in the past few decades. The cause of the disturbed benthic community is unlikely to be anthropogenic eutrophication, if there is little discordance between the living and the death assemblage in the northern, low-salinity section of the bay. Comparisons of rank-order abundance (Spearman's rho) and taxonomic similarity (Jaccard-Chao index) of the living and death assemblages along the north-south gradient, however, indicate that compositional shifts occur at the northern sites only. A multivariate index analysis, M-AMBI, which integrates the AZTI Marine Biotic Index, a biotic index based on species sensitivity/tolerance to disturbances, with Shannon diversity and species richness, shows a similar pattern: ecological status shifts (from undisturbed to disturbed) in the northern but not southern sites along the north-south salinity gradient. These independent lines of evidence corroborate the inference that it is most likely anthropogenic eutrophication (and not salinity) disturbance driving observed patterns in benthic community composition. Further sampling and incorporation of geohistorical data into ongoing benthic monitoring in the estuary is recommended to establish ecological baselines where none exist, guide restoration planning, and assess the success of restoration efforts.

Watershed Sustainability Index for Langat UNESCO HELP River Basin, Malaysia

The study on Watershed Sustainability Index (WSI) has been conducted to analyst the environmental condition in the area incorporating ecological baseline and socio-economic conditions. WSI is an integrated indicator based on basin Hydrology, Environment, Life and Policy (HELP) state condition. It is suitable to be applied in the Langat River Basin in Malaysia which has similar catchment area (up to 2,350 km2) and is one of the UNESCO HELP River Basin since 2004. The WSI analysis which uses a pressure–state–response function based on basin HELP Indicator was done for Langat River Basin by using relevant available 5 years data for the period of 2009 to 2013. It is found that Langat River Basin is having WSI value of 0.68 which falls under the category of medium sustainability (between 0.5-0.8). Based on the maximum value (i.e. 1) or high sustainability (i.e. WSI value more than 0.8) it can be said that Langat is in the good side in term of sustainability. Few management aspects need to be improved and maintained well to be more sustainable. The assessment provides Langat River Basin with more information that is crucial in managing the basin through the adoption of UNESCO’s HELP Framework.

Diverse Ecological Pathways of Salmon Nutrients Through an Intact Marine-terrestrial Interface

Based on five years of field studies (1992, 1993, 1994, 1998, 2000), I quantified bi-directional movement of salmon nutrients through an estuary, stream, and old growth forest in a large protected reserve on Haida Gwaii, British Columbia. In 1993, when most data were collected, about 6000 Chum Salmon (Oncorhynchus keta) entered the river of which 22% of the total biomass of senescent carcasses were swept downstream into the estuary and were scavenged by gulls (n = 350) and subtidal invertebrates. Of the 3700 salmon (10 000 kg) transferred by American Black Bear (Ursus americanus) to the riparian zone and partially consumed along the 800 m of stream channel, 5070 kg of salmon tissues abandoned by the bears were scavenged by Northwestern Crows (Corvus caurinus; n = 200) but mostly (4100 kg) by calliphorid blowfly larvae resulting in larval densities averaging 240/m2 throughout the riparian zone. Total nitrogen input to the soils from the combined effects of bear and scavenger activity as well as carcass input was 18 g/m2 within 10 m of the stream channel. δ15N of foliar tissues of Lanky Moss (Rhytidiadelphus loreus), Red Huckleberry (Vaccinium parvifolium), Salal (Gaultheria shallon), and Western Hemlock (Tsuga heterophylla) ranged about 15‰ to 20‰ among adjacent microsites in each species, with higher values occurring in salmon carcass zones. Total nitrogen in foliar tissues ranged from 1% to 2.4% among microsites and was best predicted by positive correlations with foliar 15N values and secondarily by presence/absence of salmon carcasses. This is the first study to integrate estuarine to riparian ecological processes in the cycling of salmonid nutrients and identifies a range of ecological baselines that can inform the multiple restoration programs underway in degraded watersheds in the North Pacific.

Suitability Evaluation of Urban Construction Land Based on an Approach of Vertical-Horizontal Processes

Suitability evaluation of urban construction land is critical for both urban master planning and the proper utilization of land resources. Using the Beihu New District of Jining City, China, as a case study, this paper introduces a novel research approach for comprehensive suitability evaluation based on vertical-horizontal processes. First, by considering both the land development potential and ecological constraint resistance, the potential-resistance (PR) model was developed and used to analyze the suitability for urban construction of vertical processes. Then, given the results of the vertical suitability analysis, the current urban built-up areas were selected as the sources of urban expansion, and the minimum cumulative resistance (MCR) model was applied to evaluate the suitability for urban development in terms of horizontal processes. The study area was regionalized into four categories—priority, suitable, restricted, and prohibited areas—which were defined based on the development threshold. The results showed that restricted and prohibited areas for urban construction occupied most of the study area. Totally, 648.51 km2 was categorized as restricted or prohibited, accounting for 12.89% and 54.75% of the total area, respectively. Priority and suitable areas for urban construction covered a total area of 310.37 km2, accounting for 16.55% and 15.81% of the total area, respectively. These areas were mainly distributed around urban centers and urban built-up areas. These findings reflect the substantial potential for future urban development and construction in the study area. The newly developed principles and methods of suitability evaluation for urban construction land presented in this paper provide more appropriate scales and spatial location for urban development and an ecological baseline for future urban growth.

Identifying management challenges and implementation shortcomings of a new fishing refuge: Akumal reef, Mexico

No-take marine reserves (fish refuges -FR-in Mexico) eliminate fishing pressure for long periods in delimited areas, promoting fish reproduction and recruitment, recovery of fish community abundance and biomass, augment resistance and resilience in coral reef-associated marine ecosystems, and support local fishing-based economies. A FR was implemented on Akumal reef in 2015 limiting fishing for six years with the specific aim of increasing the biomass of commercial and sport-recreational interest fish species. However, no previous reference data were considered to establish an ecological baseline to quantify progress towards this aim, or to implement any other policy necessary to ensure compliance with this objective. To fill this gap, Akumal FR's current level of potential success was assessed (relating reef fish community characteristics and habitat components characteristics). FR's potential success was quantified as low due to the absence of 50% of listed commercial-sport fish species, critical biomass values for recorded species on the list, and generally low reef fish abundance and biomass values. In addition, current habitat condition is critical because of coral-algal phase shift, changes in coral community structure, and loss of reef structure and the associated reef's refuge function for fish species. Considering the performance of existing no-take marine reserves, Akumal low FR's potential success implies that a much longer no-take period (than the established six years), will be necessary to allow reef fish populations to recover biomass and attain functional levels within the ecosystem that could support on-going fishing impact. Based on this, a number of recommendations were established in order to strengthen the management provisions to allow the reef to attain a better condition, including an extension of the no-take period, enforcement of non-extractive uses, and simultaneous implementation of coastal management strategies.

Shifting baselines in a changing world: Identifying management targets in endangered heathlands of the Cape Floristic Region, South Africa

Abstract Ecological baselines are important in informing conservation management targets. Baselines can shift, however, depending on the timescale of observation. Using observations from the past few years or decades can give a misleading impression of the normal range of variability of an ecosystem, and the extent of recent human transformation. Palaeoecological techniques can track interacting effects of climate change and land-use on vegetation composition and fire regimes over decadal–millennial timescales, thereby informing ecologically possible management options. In the Cape Floristic Region, South Africa, European settlement and subsequent land transformation led to dramatic changes in land-cover. Ninety-six percent of Renosterveld, a highly diverse indigenous shrubland, has been transformed. Thus, appropriate management of remaining Renosterveld fragments is critical to biodiversity conservation in this endangered habitat. However, we know little of the Renosterveld landscapes before colonial settlement from the mid-17th century. This study used fossil pollen, coprophilous fungal spores and charcoal to track vegetation, herbivory and fire at centennial timescales in one of the few remaining Renosterveld fragments. Results showed that the current landscape at the study site is atypical compared with the long-term history of the site, with higher abundance of Renosterbos (Elytropappus rhinocerotis) and local fires and herbivory that reflect intensive utilisation beginning in the mid-20th century. Managing the integrity and composition of Renosterveld at this site according to a pre-colonial baseline will require lower levels of herbivory and less frequent fire. This study illustrates how palaeoecological techniques can inform conservation management and restoration targets. To accommodate uncertainties in future environmental change, we recommend an adaptive management approach, which incorporates palaeoecological analyses, burning and grazing experiments and long-term monitoring.

Multi-dimensional eco-land classification and management for implementing the ecological redline policy in China

The ecological civilization characterized by the ecological redline policy (ERP) has been a new long-term national development strategy in China. The ERP emphasizes the need to define ecological baseline areas to provide ecosystem services and guarantee the national ecological safety. Eco-land units delineated by the individual spatial boundaries of ecosystems may facilitate an understanding of ecosystem patterns and the associated ecological processes at the landscape level. An eco-land classification system may help to identify and manage ecological baseline areas. In this study, a multi-dimensional eco-land classification system was designed to show how eco-land types could provide a reliable work platform for implementing the ERP and land management. Based on previous studies of eco-land types, we extracted three characteristics comprising the scale dependence, functional dominance, and adaptability of management. These three features were then integrated with the existing land use classification to develop a hierarchical eco-land classification system with four primary classes (fundamental eco-land, auxiliary eco-land, productive eco-land, and daily-life eco-land), 11 secondary classes, and 21 sub-secondary classes. Using a performance index based on spatial overlay analysis, we found that the fundamental eco-land covered up to 65% of the ecological redlining areas at the national scale, but not in some physical geographical regions. Thus, productive eco-land, auxiliary eco-land, and daily-life eco-land were also classified to fill the national level gaps among fundamental eco-lands, where the percentage cover of eco-land types at both the regional and urban scales could exceed 65% of the ecological redlining areas at the corresponding scale. Therefore, the disconnected fundamental eco-lands within ecological redlining areas at the national scale might be linked together as a conterminous green infrastructure if productive, auxiliary, and daily-life eco-land types located in strategic gap sites can be identified and protected at regional and urban scales. The eco-land classification system developed in this study may provide a useful land management framework for implementing the new ERP in China.

Unrecognized loss of seagrass communities based on molluscan death assemblages: historic baseline shift in tropical Gulf of Aqaba, Red Sea

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 589:73-83 (2018) - DOI: https://doi.org/10.3354/meps12492 Unrecognized loss of seagrass communities based on molluscan death assemblages: historic baseline shift in tropical Gulf of Aqaba, Red Sea Ehud Gilad1,2, Susan M. Kidwell3, Yehuda Benayahu2, Yael Edelman-Furstenberg1,* 1Geological Survey of Israel, Jerusalem 95501, Israel 2Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel 3Department of Geophysical Sciences, University of Chicago, Chicago, IL 60637, USA *Corresponding author: yael@gsi.gov.il ABSTRACT: Anthropogenic stresses on the naturally oligotrophic Gulf of Aqaba over the last 50 yr are suspected to have had a strong impact on biota, but the status of benthic fauna on the extensive soft-sediment seafloors is unknown. This study represents the first research on possible anthropogenic impacts on benthic marine fauna other than corals in the Gulf of Aqaba, a region of exceptional biodiversity. Comparing the species and functional-group composition of the living bivalve community to dead-shell assemblages from the modern seabed (top 5 cm) at 15 and 30 m water depth, both proximal and distal to historic point sources of nutrients, reveals that the ecological baseline has shifted. Live-dead discordance is strongest in the area of former sewage outfall and fish farm operations where seagrass is now functionally absent, but molluscan trophic structure has changed significantly even at distal sites where seagrass is still moderately abundant. Chemosymbiont-bearing lucinid bivalves specialized to sandy seagrass dominate death assemblages but are scarce to absent in living assemblages, which are dominated instead by facultative deposit-feeding bivalves which prefer muddy sand or muddy seagrass, consistent with organic enrichment. Seagrass habitat has thus changed qualitatively even where it persists, and sites of seagrass loss have not recovered despite cessation of major pollution ≥10 yr ago. Although shells of dead-only species require geological age-dating to definitively establish human drivers, the documentation of significant habitat change and trophic restructuring makes a powerful case for adoption of paleontological analysis by environmental managers and conservation biologists. KEY WORDS: Live-dead analysis · Bivalves · Anthropogenic modification · Paleoecology · Gulf of Aqaba · Eutrophication Full text in pdf format Supplementary material PreviousNextCite this article as: Gilad E, Kidwell SM, Benayahu Y, Edelman-Furstenberg Y (2018) Unrecognized loss of seagrass communities based on molluscan death assemblages: historic baseline shift in tropical Gulf of Aqaba, Red Sea. Mar Ecol Prog Ser 589:73-83. https://doi.org/10.3354/meps12492 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 589. Online publication date: February 23, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

The ecosystem baseline for particle flux in the Northern Gulf of Mexico

Response management and damage assessment during and after environmental disasters such as the Deepwater Horizon (DWH) oil spill require an ecological baseline and a solid understanding of the main drivers of the ecosystem. During the DWH event, a large fraction of the spilled oil was transported to depth via sinking marine snow, a routing of spilled oil unexpected to emergency response planners. Because baseline knowledge of particle export in the Northern Gulf of Mexico and how it varies spatially and temporally was limited, we conducted a detailed assessment of the potential drivers of deep (~1400 m depth) particle fluxes during 2012–2016 using sediment traps at three contrasting sites in the Northern Gulf of Mexico: near the DWH site, at an active natural oil seep site, and at a site considered typical for background conditions. The DWH site, located ~70 km from the Mississippi River Delta, showed flux patterns that were strongly linked to the Mississippi nitrogen discharge and an annual subsequent surface bloom. Fluxes carried clear signals of combustion products, which likely originated from pyrogenic sources that were transported offshore via the Mississippi plume. The seep and reference sites were more strongly influenced by the open Gulf of Mexico, did not show a clear seasonal flux pattern, and their overall sedimentation rates were lower than those at the DWH site. At the seep site, based on polycyclic aromatic hydrocarbon data, we observed indications of three different pathways for “natural” oiled-snow sedimentation: scavenging by sinking particles at depth, weathering at the surface before incorporation into sinking particles, and entry into the food web and subsequent sinking in form of detritus. Overall, sedimentation rates at the three sites were markedly different in quality and quantity owing to varying degrees of riverine and oceanic influences, including natural seepage and contamination by combustion products.

Edenic Views in Wetland Conservation: Nature and Agriculture in the Fogliano Area, Italy

The article explores the genealogy of Edenic narratives about the Pontine Marshes in Agro Pontino, Italy, and the imaginary of the Bonifica Integrale (integral reclamation). This process of reclamation, implemented by the fascist regime throughout the 1930s, drained the Marshes transforming their ecological, economic, and social structure. The dominant reading of Agro Pontino's history is polarised through a dualistic view that sees the Marshes as the realm of an almost pristine nature and the Bonifica Integrale as a life-giving event that transformed that environment, making it cultivable and inhabitable. This view reflects a modernist understanding of time as a series of punctuated events in a linear trajectory that leads to environmental degradation. In conservation, this interpretation produces problematic political effects resulting in a specific approach that positions agriculture and nature on opposite sides. The article presents ethnographic materials that challenge this view and suggests a different approach, an ‘Anthropocene conservation', which looks at the sustainability of the future rather than defining an ecological baseline to restore.