A perceived recent increase in global jellyfish abundance has been portrayed as a symptom of degraded oceans. This perception is based primarily on a few case studies and anecdotal evidence, but a formal analysis of global temporal trends in jellyfish populations has been missing. Here, we analyze all available long-term datasets on changes in jellyfish abundance across multiple coastal stations, using linear and logistic mixed models and effect-size analysis to show that there is no robust evidence for a global increase in jellyfish. Although there has been a small linear increase in jellyfish since the 1970s, this trend was unsubstantiated by effect-size analysis that showed no difference in the proportion of increasing vs. decreasing jellyfish populations over all time periods examined. Rather, the strongest nonrandom trend indicated jellyfish populations undergo larger, worldwide oscillations with an approximate 20-y periodicity, including a rising phase during the 1990s that contributed to the perception of a global increase in jellyfish abundance. Sustained monitoring is required over the next decade to elucidate with statistical confidence whether the weak increasing linear trend in jellyfish after 1970 is an actual shift in the baseline or part of an oscillation. Irrespective of the nature of increase, given the potential damage posed by jellyfish blooms to fisheries, tourism, and other human industries, our findings foretell recurrent phases of rise and fall in jellyfish populations that society should be prepared to face.

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miCHael n daWson, maRy betH deCKeR, Claudia e. mills, JennifeR e. PuRCell, alenKa maleJ, HeRmes mianzan, sHin-iCHi uye, stefan GelCiCH, and lauRenCe P. madin During the past several decades, high numbers of gelatinous zooplankton species have been reported in many estuarine and coastal ecosystems. Coupled with media-driven public perception, a paradigm has evolved in which the global ocean ecosystems are thought to be heading toward being dominated by "nuisance" jellyfish. We question this current paradigm by presenting a broad overview of gelatinous zooplankton in a historical context to develop the hypothesis that population changes reflect the human-mediated alteration of global ocean ecosystems. To this end, we synthesize information related to the evolutionary context of contemporary gelatinous zooplankton blooms, the human frame of reference for changes in gelatinous zooplankton populations, and whether sufficient data are available to have established the paradigm. We conclude that the current paradigm in which it is believed that there has been a global increase in gelatinous zooplankton is unsubstantiated, and we develop a strategy for addressing the critical questions about long-term, human-related changes in the sea as they relate to gelatinous zooplankton blooms.

jellyfish (Cnidaria, Scyphozoa) blooms appear to be increasing in both intensity and frequency in many coastal areas worldwide, due to multiple hypothesized anthropogenic stressors. Here, we propose that the proliferation of artificial structures-associated with (1) the exponential growth in shipping, aquaculture, and other coastal industries, and (2) coastal protection (collectively, "ocean sprawl")-provides habitat for jellyfish polyps and may be an important driver of the global increase in jellyfish blooms. However, the habitat of the benthic polyps that commonly result in coastal jellyfish blooms has remained elusive, limiting our understanding of the drivers of these blooms. Support for the hypothesized role of ocean sprawl in promoting jellyfish blooms is provided by observations and experimental evidence demonstrating that jellyfish larvae settle in large numbers on artificial structures in coastal waters and develop into dense concentrations of jellyfish-producing polyps.

The mesohaline region of Chesapeake Bay had high densities of the scyphomedusan Chrysaora quinquecirrha and low densities of the ctenophore

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In the vicinity of the Pribilof Islands in the Bering Sea, abundance of food available to surface-foraging seabirds was greater during the chick-rearing period in 1988 than in 1987, whereas abundance of food available to pursuit-diving seabirds was greater in 1987. Here we examine how breeding success and resource allocation of surface-foraging black-legged kittiwakes Rissa tridactyla (BLKI) and pursuit-diving thick-billed murres Uria lomvia (TBMU) varied with the fluctuations in their food supply. We also examine a difference in resource allocation among parents raising chicks at the large colony on St. George Island and those at the nearby small colony on St. Paul Island. We studied breeding success (BS), field metabolic rates (FMR, assessed by using doubly labeled water), foraging distribution, and nest attendance of parents and growth rate (GR) of chicks. The BS of BLKIs was lower in 1987 (a season of less abundant food for kittiwakes) than in 1988 (a season of more abundant food), and parents had higher FMRs in 1987 than in 1988. At-sea distributions and nest attendance suggested that in 1987 BLKIs foraged farther from the colonies, which could have resulted in the higher FMR of the parents. GR of BLKI chicks did not vary between 1987 and 1988. The BS of TBMUs was not significantly different between 1987 (a season of more abundant food for TBMUs) and 1988 (a season of less abundant food). Parent TBMUs had similar FMRs between the seasons. Densities of foraging TBMUs were higher within 20 km around colonies in 1987 than in 1988. Although the total time parent TBMUs spent foraging did not vary inter-seasonally, they performed more foraging trips of a shorter duration in 1987 than in 1988, and the GR of TBMU chicks was higher in 1987 than in 1988. Inter-colony comparisons do not suggest that parents reproducing at the large colony work harder to raise their young compared to parents breeding at the small colony. In 1987 parent BLKIs failed in raising young at the large colony, whereas one-third of BLKIs fledged their chicks at the small colony. In 1988, however, RS and FMRs of parent BLKIs were not significantly different between the colonies. Also, TBMUs at the large colony had higher BS than those at the small colony in both 1987 and 1988. Furthermore, in both years parent TBMUs feeding young at the small colony foraged farther from the colony and had significantly higher FMRs than at the large colony. These results suggest that fluctuations in food supply affect resource allocation in seabirds. However, a decrease in food abundance is likely to cause an increase in energy expenditures of parent BLKIs, whereas growth rates of their chicks are less affected. For the TBMUs, food shortages are likely to cause a decrease in growth of the chicks, but not an increase in energy expenditures of the parents. KEY WORDS: Doubly labeled water · Field metabolic rates · Food abundance · Kittiwakes · MurresResale or republication not permitted without written consent of the publisher

We investigated the foraging distribution of 2 species of murres (Uria lomvia and U. aalge) in relation to Acoustically Determined Biomass (ADB) and hydrographic structure surrounding the Pribilof Islands, Bering Sea, Alaska, USA. The distribution and abundance of both murre species were similar; therefore, we combined data for thick-billed and common murres in the analysis. We found that murre densities were higher in frontal regions than in non-frontal regions. Maximum ADB was also found to be elevated in the frontal zone. Within frontal regions, high densities of rnurres were associated with regions containing relatively high levels of ADB. In contrast, we did not find significant correlations between murre density and ADB in the study area as a whole. We postulate that rnurres restrict their foraging to the frontal region because prey can be located more predictably within this zone than in other areas in the vicinity of the Pribilof Islands.