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

Much has been written about theory and practice in the law, and the tension between practitioners and theorists. Judges do not cite theoretical articles often; they rarely "apply" theories to particular cases. These arguments are not revisited. Instead the Essay explores the working and interaction of theory and practice, practitioners and theorists. The Essay starts with a story about solving a legal issue using our intellectual tools - theory, practice, and their progenies: experience and "gut." Next the Essay elaborates on the nature of theory, practice, experience and "gut." The third part of the Essay discusses theories that are helpful to practitioners and those that are less helpful. The Essay concludes that practitioners theorize, and theorists practice. They use these intellectual tools differently because the goals and orientations of theorists and practitioners, and the constraints under which they act, differ. Theory, practice, experience and "gut" help us think, remember, decide and create. They complement each other like the two sides of the same coin: distinct but inseparable.

Of Theory and Practice

Predation is a central feature of ecological communities. Most theoretical and empirical studies of predation focus on the consequences of predators consuming their prey. Predators reduce prey population densities through direct consumption (a density- mediated interaction, DMI), a process that may indirectly affect the prey's resources, com- petitors, and other predators. However, predators can also affect prey population density by stimulating costly defensive strategies. The costs of these defensive strategies can include reduced energy income, energetic investment in defensive structures, lower mating success, increased vulnerability to other predators, or emigration. Theoretical and empirical studies confirm the existence of these induced costs (trait-mediated interactions, TMIs); however, the relative importance of intimidation (TMI) and consumption (DMI) effects remains an open question. We conducted a meta-analysis assessing the magnitude of both TMIs and DMIs in predator-prey interactions. On average, the impact of intimidation on prey de- mographics was at least as strong as direct consumption (63% and 51% the size of the total predator effect, respectively). This contrast is even more pronounced when we consider the cascading effects of predators on their prey's resources: density effects attenuated through food chains, while TMIs remained strong, rising to 85% of the total predator effect. Predators can thus strongly influence resource density even if they consume few prey items. Finally, intimidation was more important in aquatic than terrestrial ecosystems. Our results suggest that the costs of intimidation, traditionally ignored in predator-prey ecology, may actually be the dominant facet of trophic interactions.

Scared to death? the effects of intimidation and consumption in predator–prey interactions

Recent studies document unprecedented declines in marine top predators that can initiate trophic cascades. Predicting the wider ecological consequences of these declines requires understanding how predators influence communities by inflicting mortality on prey and inducing behavioral modifications (risk effects). Both mechanisms are important in marine communities, and a sole focus on the effects of predator-inflicted mortality might severely underestimate the importance of predators. We outline direct and indirect consequences of marine predator declines and propose an integrated predictive framework that includes risk effects, which appear to be strongest for long-lived prey species and when resources are abundant. We conclude that marine predators should be managed for the maintenance of both density- and risk-driven ecological processes, and not demographic persistence alone.

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Predicting ecological consequences of marine top predator declines

Cet article analyse les relations conceptuelles (imprecises) de la vulnerabilite, de la resilience et de la capacite d’adaptation aux changements climatiques selon le systeme socio-ecologique (socio-ecologigal systems – SES) afin de comprendre et anticiper le comportement des composantes sociales et ecologiques du systeme. Une serie de questions est proposee par l’auteur sur la specification de ces termes afin de developper une structure conceptuelle qui inclut les dimensions naturelles et so...

Linkages between vulnerability, resilience, and adaptive capacity

Factors affecting recruitment, growth and survival of the eastern oyster Crassostrea virginica across an intertidal elevation gradient in southern New England

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Growth of juvenile American lobster Homarus americanus in a changing environment

The warming of the world’s oceans has resulted in the redistribution of many marine species globally. As species undergo range shifts, the expanding edge of the population often experiences novel environmental and demographic conditions that may result in the emergence of variation in life-history strategies. The northern stock of black sea bass, Centropristis striata, has recently expanded its distribution poleward, into the Gulf of Maine. Management has struggled to keep pace with this rapid range shift, in part, because very little is known about the expanding population. We compared life-history traits of black sea bass collected from 2013-2016 from the northern most point of the historic range of the northern stock (southern Massachusetts) to those from two areas in the newly expanded range (northern Massachusetts and Maine). We found significant differences in size, diet, condition, maturity and sex ratio between black sea bass from southern Massachusetts and the Gulf of Maine. Overall, sea bass in the newly expanded range consumed a less diverse diet and their condition was lower, but they reached maturity at a younger age. We also found greater length- and age-at-maturity estimates from all regions combined compared to the most recent black sea bass stock assessment which includes data from Cape Hatteras, NC to southern Massachusetts. This study represents initial observations of life-history traits of sea bass in its newly expanded range in the Gulf of Maine, and suggests that these sea bass exhibit life-history strategies that differ from their southern counterparts within their historic range. Given these findings, the stock assessment for the Northeast U.S. Continental Shelf black sea bass stock may not be adequate for sea bass in the Gulf of Maine. Studies investigating the expanding edge of economically valuable fishery species are needed to aid in ongoing and future efforts to assess and manage their stocks.

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Geographic Variation in Life-History Traits of Black Sea Bass (Centropristis striata) During a Rapid Range Expansion

The rapid growth of the aquaculture industry to meet global seafood demand offers both risks and opportunities for resource management and conservation. In particular, hatcheries hold promise for stock enhancement and restoration, yet cultivation practices may lead to enhanced variation between populations at the expense of variation within populations, with uncertain implications for performance and resilience. To date, few studies have assessed how production techniques impact genetic diversity and population structure, as well as resultant trait variation in and performance of cultivated offspring. We collaborated with a commercial hatchery to produce multiple cohorts of the eastern oyster (Crassostrea virginica) from field-collected broodstock using standard practices. We recorded key characteristics of the broodstock (male : female ratio, effective population size), quantified the genetic diversity of the resulting cohorts, and tested their trait variation and performance across multiple field sites and experimental conditions. Oyster cohorts produced under the same conditions in a single hatchery varied almost twofold in genetic diversity. In addition, cohort genetic diversity was a significant positive predictor of oyster performance traits, including initial size and survival in the field. Oyster cohorts produced in the hatchery had lower within-cohort genetic variation and higher among-cohort genetic structure than adults surveyed from the same source sites. These findings are consistent with "sweepstakes reproduction" in oysters, even when manually spawned. A readily measured characteristic of broodstock, the ratio of males to females, was positively correlated with within-cohort genetic diversity of the resulting offspring. Thus, this metric may offer a tractable way both to meet short-term production goals for seafood demand and to ensure the capacity of hatchery-produced stock to achieve conservation objectives, such as the recovery of self-sustaining wild populations.

Genetic diversity and phenotypic variation within hatchery-produced oyster cohorts predict size and success in the field

Nearshore marine ecosystems are among the most productive areas in the world. Unfortunately, these areas also receive pollutants released into oceanic and riverine waters. Six years following the Deepwater Horizon oil spill, the largest in US history, the complexity of ecological injuries in this system is just now being elucidated. Here, we describe a novel pathway of injury from oil spills by documenting how the loss of oysters near marsh edge as a direct result of shoreline oiling and clean-up activities can double rates of coastal erosion. As part of the natural resource damage assessment, we examined the impact of shoreline oiling on eastern oysters Crassostrea virginica near the marsh edge at 187 sites in Louisiana and Mississippi Sound in 2013. For marshes that experienced heavy oiling, oyster habitat was 77% less abundant than in areas where no oil was observed. Areas near marshes characterized by more moderate levels of oiling had 33% less oyster habitat than areas where no oil was observed. Similarly, the number of sites without any oyster habitat was higher in heavily and persistently oiled areas compared to areas where no oil was observed (56 vs. 24%). The consequences of this loss are substantial and include loss of essential fish habitat, reduced nutrient cycling, and decreased erosion buffering. For a subset of the sites where erosion rate was also measured between 2010 and 2013 (n = 79), shoreline loss was more than twice as high (2.1 vs. 0.9 m yr−1) in areas lacking oyster cover. Our findings provide evidence that loss of nearshore oyster habitat can disrupt the strong facilitation between oysters and marsh vegetation.

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Jonathan H. Grabowski

Papers

Factors affecting recruitment, growth and survival of the eastern oyster Crassostrea virginica across an intertidal elevation gradient in southern New England

Growth of juvenile American lobster Homarus americanus in a changing environment

Geographic Variation in Life-History Traits of Black Sea Bass (Centropristis striata) During a Rapid Range Expansion

Genetic diversity and phenotypic variation within hatchery-produced oyster cohorts predict size and success in the field

Ecosystem services are lost when facilitation between two ecosystem engineers is compromised by oil