Jellyfish and Ctenophore Blooms Coincide with Human Proliferations and Environmental Perturbations

Abstract

Human populations have been concentrated along and exploiting the coastal zones for millennia. Ofregions with the highest human impacts on the oceans (Halpern et al. 2008), 6 of the top 10 have recently experienced blooms or problems with jellies. I review the time lines of human population growth and their effects on the coastal environment. I explore evidence suggesting that human activities--specifically, seafood harvest, eutrophication, hard substrate additions, transport ofnonindigenous species, aquaculture, and climate change--may benefit jelly populations. Direct evidence is lacking for most of these factors; however, numerous correlations show abundant jellies in areas with warm temperatures and low forage fish populations. Jelly populations fluctuate in approximately 10- and approximately 20-year cycles in concert with solar and climate cycles. Global warming will provide a rising baseline against which climate cycles will cause fluctuations in jelly populations. The probable acceleration of anthropogenic effects may lead to further problems with jellies.

Human envenomations caused by Portuguese man-of-war (Physalia physalis) in urban beaches of São Luis City, Maranhão State, Northeast Coast of Brazil

“…Such events have been observed annually in specific months, especially during the summer and school holidays. Recent studies have shown a correlation between the presence of cnidarians and global warming 5,12 . In 2008, São Luis registered its highest ever number of envenomations.…”

“…These sophisticated cells feature an apparatus for venom inoculation, the cnidas (especially nematocysts). The venom comprises a complex mix of toxic polypeptides and high-molecular-weight enzymes, including methyl-ammonium hydroxide, serotonin, and histamine 5 .…”

Role of winds and tides in timing of beach strandings, occurrence, and significance of swarms of the jellyfish Crambione mastigophora Mass 1903 (Scyphozoa: Rhizostomeae: Catostylidae) in north-western Australia

“…Details on the occurrence of C. mastigophora swarms in 1976, 2000, 2006, 2007, 2010, 2011, 2012, and 2013 were collated from a series of eye witness accounts by the authors and their associates: JK, TT, DB, JS, LG in 2010, 2012, TT, KO in 2011and TT in 2006 and others as well as reports to the Western Australian Museum (Marsh & Slack-Smith, 2010), the Western Australian Department of the Environment, the Broome Shire Council (Cable Beach life guard logbooks), the Eighty Mile Beach Caravan Park and from news reports. For the period of detailed investigation on Cable Beach (Fig.…”

“…Climate change, overfishing and coastal development have all been suggested as contributing to jellyfish swarms and blooms, although the evidence is often equivocal (Mills, 2001;Purcell et al, 2007;Richardson et al, 2009;Dong et al, 2010;Lilley et al, 2011;Duarte et al, 2012;Purcell, 2012;Gibbons & Richardson, 2013), and the evidence of a world-wide trend in jellyfish swarms and blooms is debated (Condon et al, , 2013). The jellyfish swarms described in this study occurred in the remote northwestern Australia, where anthropogenic impacts are regarded as being very low on a global scale (Halpern et al, 2008) offering an opportunity to examine the drivers of swarms as well as their ecological, social and economic significance.…”

Marine ecology: Attack of the blobs

“…Most of the researchers who have questioned the idea of a jellyfish explosion say they cannot rule out the possibility that blooms are becoming more prevalent or that humans are at least partly responsible 6 . In Japan, for example, longterm records suggest that blooms happened only every 40 years or so before 2000, but have come nearly every year since 7 .…”