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Does humanity's future lie in the ocean? As demand for resources continues to grow and land-based sources decline, expectations for the ocean as an engine of human development are increasing. Claiming marine resources and space is not new to humanity, but the extent, intensity, and diversity of today's aspirations are unprecedented. We describe this as the blue acceleration—a race among diverse and often competing interests for ocean food, material, and space. Exploring what this new reality means for the global ocean and how to steer it in a sustainable and equitable way represents an urgent challenge.

In a world of increasing interconnections in global trade as well as rapid change in climate and land cover, the accelerating introduction and spread of invasive species is a critical concern due to associated negative social and ecological impacts, both real and perceived. Much of the societal response to invasive species to date has been associated with negative economic consequences of invasions. This response has shaped a war-like approach to addressing invasions, one with an agenda of eradications and intense ecological restoration efforts towards prior or more desirable ecological regimes. This trajectory often ignores the concept of ecological resilience and associated approaches of resilience-based governance. We argue that the relationship between ecological resilience and invasive species has been understudied to the detriment of attempts to govern invasions, and that most management actions fail, primarily because they do not incorporate adaptive, learning-based approaches. Invasive species can decrease resilience by reducing the biodiversity that underpins ecological functions and processes, making ecosystems more prone to regime shifts. However, invasions do not always result in a shift to an alternative regime; invasions can also increase resilience by introducing novelty, replacing lost ecological functions or adding redundancy that strengthens already existing structures and processes in an ecosystem. This paper examines the potential impacts of species invasions on the resilience of ecosystems and suggests that resilience-based approaches can inform policy by linking the governance of biological invasions to the negotiation of tradeoffs between ecosystem services.

The composition and functions of many ecosystems are changing, giving rise to the concept of novel ecosystems. Although some coral reefs are becoming non-coral systems, others are becoming novel coral-dominated ecosystems driven principally by differential species responses to climate change and other drivers, but also due to species range shifts at higher latitudes, and in some cases introduced species. Returning many coral reefs to pristine baselines is unrealistic, whereas embracing novel futures enables more pragmatic approaches to maintaining or re-building the dominance of corals. Coral reefs are changing in unprecedented ways, providing the impetus to improve our understanding of reef compositions that may dominate in the future, explore new management approaches, assess changes in ecosystem services, and investigate how human societies can adapt and respond to novel futures.

Coral reef fish are an important source of food security and income for human coastal populations. They also underpin ecosystem processes vital for the future ability of coral reefs to generate eco ...

Applying a broader landscape perspective to understand spatio-temporal changes in local populations and communities has been increasingly used in terrestrial systems to study effects of human impac ...

Effects of elevated seawater temperature show high spatial heterogeneity and variation within and among coral species. The objective of this study was to investigate how two coral species, Porites lutea and Galaxea fascicularis, from two high latitude reefs differently exposed to chronic disturbance, respond to elevated seawater temperatures. Corals were collected from reefs nearshore (i.e. subjected to high sediment load, higher chlorophyll α concentrations, turbidity etc.) and offshore (i.e. less exposed). The corals were exposed in the lab to gradually increasing temperatures (25.5-33.5 °C) for 72 h after which they were allowed to recover to ambient temperature (25.5 °C) for 24 h. Production and respiration were measured after 24, 48, 72 and 96 h. The results show that P. lutea from nearshore reefs suffered an initial decrease in gross primary production/respiration (GP/R) ratio after 24 h, after only a moderate temperature increase (+2 °C, from 25.5 to 27.5 °C), while there was no difference in GP/R ratio between heat-exposed and controls the other days, indicating that the chronic disturbance in the nearshore reef had no effect on their thermotolerance. Furthermore, P. lutea from the offshore reef showed a decrease in GP/R ratio both after 24 h and 72 h (33.5 °C) of exposure. In comparison, G. fascicularis showed a decrease in GP/R ratio after 48 h, 72 h and 96 h of exposure for the nearshore corals. Also, after 72 h these corals had withdrawn their polyps. There were no differences between heat-treated and controls for the offshore G. fascicularis. This implies that the chronically disturbed G. fascicularis had lower thermotolerance when exposed to a temperature increase. This study, hence, shows that the response of corals to elevated seawater temperature varies with species and environmental background history.

This paper analyzes the middlemen-fishermen link in coastal communities along the coast of southern Kenya and Zanzibar, and explores effects of reciprocal agreements and credit arrangements on soci ...

This study investigates the physiological responses in the hermatypic coral Porites lutea when exposed to a combination of reduced salinity (from ambient 30 psu to 20 psu) and two concentrations of copper (CuS04), 10 microg 1(-1) and 30 microg 1(-1). Corals were exposed for 14 h and changes in metabolism in terms of primary production rate per chlorophyll a and respiration per surface area (cm2) were used as measures of stress. The results showed no significant changes in respiration rate in any of the treatments compared with controls, or between treatments. The primary production rate, however, displayed a more complex pattern. Corals exposed to reduced salinity, 30 microg 1(-1) copper, and the combination of the two stressors significantly reduced the production rate, whereas corals exposed to 10 microg 1(-1) only, remained unaffected. However, adding 10 microg 1(-1) copper to reduced salinity did not affect the production rate thus indicating an antagonistic effect.

We welcome the comments made by Scully and Ostrander, which highlight that phase shifts can occur in coral areas that are not under immediate anthropogenic influence, and that they might be a natural ingredient in the dynamics of modern coral reefs. To understand such changes, we do indeed need to address the influence of natural disturbance regimes on coral reef communities, and learn more about the complex interactions between corals and macroalgae. Unfortunately, there might only be few, if any, pristine coral reefs left on which to study phase-shifts and natural disturbance regimes [Refs 1xReefs since Columbus. Jackson, J.B.C. Coral Reefs. 1997; 16: 23–32CrossrefSee all References1,2xVarieties of science for coral reef management. Hatcher, B.G. Coral Reefs. 1999; 18: 305–306Crossref | Scopus (7)See all References2 and see Bryant, D. et al. (1998) Reefs at risk. A map-based indicator of potential threats to the world's coral reefs: http://www.wri.org/wri/indictrs/reefrisk.htm]. A major point in our review3xCoral reef disturbance and resilience in a human-dominated environment. Nystrom, M et al. Trends Ecol. Evol. 2000; 15: 413–417Abstract | Full Text | Full Text PDF | PubMed | Scopus (353)See all References3 was that these shifts seem to have become more frequent and less reversible because of human impacts and that humans might also alter the magnitude, frequency and duration of disturbance regimes.Many of the world's coral reefs assumed to be pristine show signs of overfishing of highly valued predatory fishes4xCoral reef fishing and coral-algal phase shifts: implications for global reef status. McManus, J.W et al. ICES J. Mar. Sci. 2000; 57: 572–578Crossref | Scopus (54)See all References4 and might already have been overfished when intensive scientific investigations began1xReefs since Columbus. Jackson, J.B.C. Coral Reefs. 1997; 16: 23–32CrossrefSee all References1. In addition, reefs with no discernible human influences might suffer from indirect human influence at scales that reach far beyond the border of the individual reef, such as global warming, increased levels of carbon dioxide5xExecutive summary. Wilkinson, C.R. : 7–19See all References5 and dust6xAfrican dust and the demise of Caribbean coral reefs. Shinn, E.A et al. Geophys. Res. Lett. 2000; 27: 3029–3032CrossrefSee all References6. Subtle interactions of a number of factors7xRapid transition in the structure of a coral reef community: The effects of coral bleaching and physical disturbance. Ostrander, G.K et al. Proc. Natl. Acad. Sci. U. S. A. 2000; 97: 5297–5302Crossref | PubMed | Scopus (87)See all References7 can lead to a loss of ecosystem resilience that is difficult to detect until a reef shifts to another stability domain caused by a disturbance that could previously be absorbed8xMacroalgae, nutrients and phase shifts on coral reefs: scientific issues and management consequences for the Great Barrier Reef. McCook, L.J. Coral Reefs. 1999; 18: 357–367Crossref | Scopus (335)See all References8. Thus, what we experience as a fast transition (within months) from one state to another might be the result of a long-term gradual change over years, decades or even centuries.This raises some key questions for future research. How do we detect gradual loss of resilience and how can we qualitatively and quantitatively measure such loss, and incorporate this knowledge in the management of coral reefs? Our understanding of factors that might signal loss of resilience is, however, still in its infancy.In order to secure the ability of coral reefs to provide humans with ecological goods and services9xEcological goods and services of coral reef ecosystems. Moberg, F and Folke, C. Ecol. Econ. 1999; 29: 215–233Crossref | Scopus (430)See all References9, we must understand the properties that enable coral reef ecosystems to maintain their resilience in the face of an increasingly human-dominated world with altered disturbance regimes3xCoral reef disturbance and resilience in a human-dominated environment. Nystrom, M et al. Trends Ecol. Evol. 2000; 15: 413–417Abstract | Full Text | Full Text PDF | PubMed | Scopus (353)See all References3.