Depletion, Degradation, and Recovery Potential of Estuaries and Coastal Seas

Biology Department, Dalhousie University, 1355 Oxford Street, Halifax, NS, Canada B3H 4J1.
Science (Impact Factor: 33.61). 07/2006; 312(5781):1806-9. DOI: 10.1126/science.1128035
Source: PubMed


Estuarine and coastal transformation is as old as civilization yet has dramatically accelerated over the past 150 to 300 years.
Reconstructed time lines, causes, and consequences of change in 12 once diverse and productive estuaries and coastal seas
worldwide show similar patterns: Human impacts have depleted >90% of formerly important species, destroyed >65% of seagrass
and wetland habitat, degraded water quality, and accelerated species invasions. Twentieth-century conservation efforts achieved
partial recovery of upper trophic levels but have so far failed to restore former ecosystem structure and function. Our results
provide detailed historical baselines and quantitative targets for ecosystem-based management and marine conservation.

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    • "c o m / l o c a t e / s c i t o t e n v exploitable resources have encouraged the extensive development of urban, agricultural and industrial areas which threaten their ecosystems (Elliott and Whitfield, 2011; Halpern et al., 2007; Lotze, 2010). Over the last century, the estuarine structure and functioning had dramatically changed because of anthropogenic stressors, such as resource overexploitation , habitat fragmentation or pollution (Aubry and Elliott, 2006; Lotze et al., 2006). The expanding degradation of estuarine conditions worldwide has pushed the environmental authorities to develop platforms aiming at assessing the ecological status of transitional waters (i.e. "
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    ABSTRACT: Estuaries are subjected to multiple anthropogenic stressors, which have additive, antagonistic or synergistic effects. Current challenges include the use of large databases of biological monitoring surveys (e.g. the European Water Framework Directive) to help environmental managers prioritizing restoration measures. This study investigated the impact of nine stressor categories on the fish ecological status derived from 90 estuaries of the North East Atlantic countries. We used a random forest model to: 1) detect the dominant stressors and their non-linear effects; 2) evaluate the ecological benefits expected from reducing pressure from stressors; and 3) investigate the interactions among stressors. Results showed that largest restoration benefits were expected when mitigating water pollution and oxygen depletion. Non-additive effects represented half of pairwise interactions among stressors, and antagonisms were the most common. Dredged sediments, flow changes and oxygen depletion were predominantly implicated in non-additive interactions, whereas the remainder stressors often showed additive impacts. The prevalence of interactive impacts reflects a complex scenario for estuaries management; hence, we proposed a step-by-step restoration scheme focusing on the mitigation of stressors providing the maximum of restoration benefits under a multi-stress context.
    Science of The Total Environment 01/2016; 542(Pt A):383-393. DOI:10.1016/j.scitotenv.2015.10.068 · 4.10 Impact Factor
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    • "Changes in marine resources and ecosystems have been documented worldwide (Butchart et al., 2010; Lotze et al., 2006) and multiple anthropogenic and climate-related drivers of change have been identified (Halpern et al., 2008). These drivers can alter ecosystem structure and functioning (Christensen et al., 2003; Frank et al., 2005) and can affect the ecosystem services that humans obtain from healthy oceans (Worm et al., 2006). "
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    ABSTRACT: IndiSeas (“Indicators for the Seas”) is a collaborative international working group that was established in 2005 to evaluate the status of exploited marine ecosystems using a suite of indicators in a comparative framework. An initial shortlist of seven ecological indicators was selected to quantify the effects of fishing on the broader ecosystem using several criteria (i.e., ecological meaning, sensitivity to fishing, data availability, management objectives and public awareness). The suite comprised: (i) the inverse coefficient of variation of total biomass of surveyed species, (ii) mean fish length in the surveyed community, (iii) mean maximum life span of surveyed fish species, (iv) proportion of predatory fish in the surveyed community, (v) proportion of under and moderately exploited stocks, (vi) total biomass of surveyed species, and (vii) mean trophic level of the landed catch. In line with the Nagoya Strategic Plan of the Convention on Biological Diversity (2011–2020), we extended this suite to emphasize the broader biodiversity and conservation risks in exploited marine ecosystems. We selected a subset of indicators from a list of empirically based candidate biodiversity indicators initially established based on ecological significance to complement the original IndiSeas indicators. The additional selected indicators were: (viii) mean intrinsic vulnerability index of the fish landed catch, (ix) proportion of non-declining exploited species in the surveyed community, (x) catch-based marine trophic index, and (xi) mean trophic level of the surveyed community. Despite the lack of data in some ecosystems, we also selected (xii) mean trophic level of the modelled community, and (xiii) proportion of discards in the fishery as extra indicators. These additional indicators were examined, along with the initial set of IndiSeas ecological indicators, to evaluate whether adding new biodiversity indicators provided useful additional information to refine our understanding of the status evaluation of 29 exploited marine ecosystems. We used state and trend analyses, and we performed correlation, redundancy and multivariate tests. Existing developments in ecosystem-based fisheries management have largely focused on exploited species. Our study, using mostly fisheries independent survey-based indicators, highlights that biodiversity and conservation-based indicators are complementary to ecological indicators of fishing pressure. Thus, they should be used to provide additional information to evaluate the overall impact of fishing on exploited marine ecosystems.
    Ecological Indicators 01/2016; 60:947-962. DOI:10.1016/j.ecolind.2015.08.048 · 3.44 Impact Factor
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    ABSTRACT: Marine protected areas (MPAs) have been widely recognized as a tool to achieve both fisheries management and conservation goals. Simultaneously achieving these multiple goals is difficult due to conflicts between conservation (often long-term) and economic (often short-term) objectives. MPA implementation often includes additional control measures on fisheries (e.g. vessel size restrictions, gear exclusion, catch controls) that in the short-term may have impacts on local fishers’ communities. Thus, monitoring fisheries catches before, during and after MPA implementation is essential to document changes in fisheries activities and to evaluate the impact of MPAs in fishers' communities. Remarkably, in contrast with standard fisheries-independent biological surveys, these data are rarely measured at appropriate spatial scales following MPA implementation. Here, the effects of MPA implementation on local fisheries are assessed in a temperate MPA (Arrábida Marine Park, Portugal), using fisheries monitoring methods combining spatial distribution of fishing effort, on-board observations and official landings statistics at scales appropriate to the Marine Park. Fisheries spatial distribution, fishing effort, on-board data collection and official landings registered for the same vessels over time were analysed between 2004 and 2010. The applicability and reliability of using landings statistics alone was tested (i.e. when no sampling data are available) and we conclude that landings data alone only allow the identification of general patterns. The combination of landings information (which is known to be unreliable in many coastal communities) with other methods, provides an effective tool to evaluate fisheries dynamics in response to MPA implementation. As resources for monitoring socio-ecological responses to MPAs are frequently scarce, the use of landings data calibrated with fisheries information (from vessels, gear distribution and on-board data) is a valuable tool applicable to many worldwide coastal small-scale fisheries.
    Fisheries Research 12/2015; 172:197-208. DOI:10.1016/j.fishres.2015.07.020 · 1.90 Impact Factor
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