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Dayton, PK, Kim S, Jarrell SC, Oliver JS, Hammerstrom K, Fisher JL, O'Connor K, Barber JS, Robilliard G, Barry J, Thurber AR, Conlan K.  2013.  Recruitment, Growth and Mortality of an Antarctic Hexactinellid Sponge, Anoxycalyx joubini. PLOS One. 8   10.1371/journal.pone.0056939   AbstractWebsite

Polar ecosystems are sensitive to climate forcing, and we often lack baselines to evaluate changes. Here we report a nearly 50-year study in which a sudden shift in the population dynamics of an ecologically important, structure-forming hexactinellid sponge, Anoxycalyx joubini was observed. This is the largest Antarctic sponge, with individuals growing over two meters tall. In order to investigate life history characteristics of Antarctic marine invertebrates, artificial substrata were deployed at a number of sites in the southern portion of the Ross Sea between 1967 and 1975. Over a 22-year period, no growth or settlement was recorded for A. joubini on these substrata; however, in 2004 and 2010, A. joubini was observed to have settled and grown to large sizes on some but not all artificial substrata. This single settlement and growth event correlates with a region-wide shift in phytoplankton productivity driven by the calving of a massive iceberg. We also report almost complete mortality of large sponges followed over 40 years. Given our warming global climate, similar system-wide changes are expected in the future.

Done, TJ, Dayton PK, Dayton AE, Steger R.  1991.  Regional and local variability in recovery of shallow coral communities: Moorea, French Polynesia and the central Great Barrier Reef. Coral Reefs. 9:183-192.   10.1007/bf00290420   AbstractWebsite

Coral communities at Moorea, French Polynesia, and on the Great Barrier Reef (GBR), Australia, were severely depleted by disturbances early in the 1980s. Corals were killed by the predatory starfish Acanthaster planci, by cyclones, and/or by depressed sea level. This study compares benthic community structure and coral population structures on three disturbed reefs (Vaipahu - Moorea; Rib and John Brewer Reefs - GBR) and one undisturbed reef (Davies Reef - GBR) in 1987-89. Moorea barrier reefs had been invaded by tall macrophytes Turbinaria ornata and Sargassum sp., whereas the damaged GBR reefs were colonised by a diverse mixture of short macrophytes, turfs and coralline algae. The disturbed areas had broadly similar patterns of living and dead standing coral, and similar progress in recolonisation, which suggests their structure may converge towards that of undisturbed Davies Reef. Corals occupying denuded areas at Vaipahu, Rib and John Brewer were small (median diameter 5 cm in each case) and sparse (means 4-8 m-2) compared to longer established corals at Davies Reef (median diameter 9 cm; mean 18 m-2). At Moorea, damselfish and sea urchins interacted with corals in ways not observed in the GBR reefs. Territories of the damselfish Stegastes nigricans covered much of Moorea's shallow reef top. They had significantly higher diversity and density of post-disturbance corals than areas outside of territories, suggesting that the damselfish exerts some influences on coral community dynamics. Sea urchins on Moorea (Diadema setosum, Echinometra mathaei, Echinotrix calamaris) were causing widespread destruction of dead standing coral skeletons. Overall, it appears that the future direction and speed of change in the communities will be explicable more in terms of local than regional processes.

Parnell, PE, Miller EF, Lennert-Cody CE, Dayton PK, Carter ML, Stebbins TD.  2010.  The response of giant kelp (Macrocystis pyrifera) in southern California to low-frequency climate forcing. Limnology and Oceanography. 55:2686-2702.   10.4319/lo.2010.55.6.2686   AbstractWebsite

The nutrient climate on the inner shelf off southern California changed markedly across the 1976-1977 North Pacific climate regime shift. With respect to giant kelp (Macrocystis pyrifera) canopies off southern California, the nitrate climate shifted from relatively replete conditions prior to the regime shift to depleted conditions afterward, and the dynamics of 14 giant kelp forests appeared to change as a result. The response of giant kelp to nutrient-replete years before the regime shift was dampened compared to their response afterward. The sensitivity of these kelp-forest canopies to nutrient limitation appears to have increased since the regime shift. This intensification of physical control after 1977 is evident in the strong correlation of seawater density (sigma(t)) and M. pyrifera density. The linear fit of the percent of time the 25.1 sigma(t) isopycnal bathes the inner shelf, accounted for similar to 71% of the variability in kelp density off Point Loma, and the median depth of this isopycnal has deepened similar to 5 m since the regime shift. The wave climate also intensified beginning in the early 1970s. The dampened kelp response prior to the regime shift was likely due to greater biological control of kelp canopies via consumer and competitive processes (i.e., biological modulation) or decreased physical control at possibly many trophic levels. Our results suggest that the response of kelp forests to El Nino Southern Oscillation events is mediated by lower frequency climate modes that may modulate the regulatory importance of biological and physical processes on giant kelp.

Christian, C, Ainley D, Bailey M, Dayton P, Hocevar J, Levine M, Nikoloyuk J, Nouvian C, Velarde E, Werner R, Jacquet J.  2013.  A review of formal objections to Marine Stewardship Council fisheries certifications. Biological Conservation. 161:10-17.   10.1016/j.biocon.2013.01.002   AbstractWebsite

The Marine Stewardship Council (MSC) was created as a conservation tool - intended to provide "the best environmental choice in seafood" to consumers and to create positive incentives that would improve the status and management of fisheries. During its 15 years, the MSC, which has an annual budget of close to US$20 million, has attached its logo to more than 170 fisheries. These certifications have not occurred without protest. Despite high costs and difficult procedures, conservation organizations and other groups have filed and paid for 19 formal objections to MSC fisheries certifications. Only one objection has been upheld such that the fishery was not certified. Here, we collate and summarize these objections and the major concerns as they relate to the MSC's three main principles: sustainability of the target fish stock, low impacts on the ecosystem, and effective, responsive management. An analysis of the formal objections indicates that the MSC's principles for sustainable fishing are too lenient and discretionary, and allow for overly generous interpretation by third-party certifiers and adjudicators, which means that the MSC label may be misleading both consumers and conservation funders. (C) 2013 Elsevier Ltd. All rights reserved.

Witman, JD, Dayton PK.  2001.  Rocky Subtidal Communities. Marine community ecology. ( Bertness MD, Gaines SD, Hay ME, Eds.).:339-366., Sunderland, Mass.: Sinauer Associates Abstract
Dayton, PK, Hessler RR.  1972.  Role of biological disturbance in maintaining diversity in the deep sea. Deep-Sea Research. 19:199-208.   10.1016/0011-7471(72)90031-9   AbstractWebsite

This paper presents the hypothesis that the maintenance of high species diversity in the deep sea is more a result of continued biological disturbance than of highly specialized competitive niche diversification. Detrital food is the primary resource for most of the deep-sea species, but we suggest that in deposit feeding, most animals would consume available living particles as well as dead. We call this dominant life-style ‘cropping’. Predictable cropping pressure on smaller animals reduces the probability of their competitive exclusion and allows a high overlap in the utilization of food resources. Since cropping pressure is in part proportional to the abundance of the prey, proliferations of individual species are unlikely.Through time many species have accumulated in the deep sea because of speciation and immigration. Extinction rate is low because the biological and physical predictability of the environment has suppressed the possibility of population oscillations. Predictability in food supply for smaller deposit feeders is enhanced by the larger, mobile scavengers which consume and disperse large particles of food which fall to the ocean floor.