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() Environmental Health BioMed Central Proceedings Impacts of climate variability and future climate change on harmful algal blooms and human health Stephanie K Moore* 1,2, Vera LTrainer2, Nathan J Mantua3, Micaela S Parker4, Edward A Laws5, Lorraine C Backer6 and Lora E Fleming7 1 2 Address: School of Oceanography, University of Washington, Box 355351, Seattle, Washington 98195-5351, USA, NOAA, Northwest Fisheries 3 Science Center, West Coast Center for Oceans and Human Health, 2725 Montlake Blvd. E., Seattle, Washington 98112-2013, USA, Climate 4 Impacts Group and School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, Washington 98195-5020, USA, Pacific 5 Northwest Center for Human Health and Ocean Studies, University of Washington, Box 357940, Seattle, Washington 98195-7940, USA, School of the Coast and Environment, 1002 K Energy, Coast and Environment Building, Louisiana State University, Baton Rouge, Louisiana 70803-4110, 6 USA, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway NE MS F-46, Chamblee, 7 Georgia 30341-3717, USA and Department of Epidemiology and Public Health and Department of Marine Biology and Fisheries, University of Miami School of Medicine and Rosenstiel School of Marine and Atmospheric Sciences, 1120 NW 14th Street, Miami; Florida 33136-2107, USA Email: Stephanie K Moore - [email protected]; Vera LTrainer - [email protected]; Nathan J Mantua - [email protected]; Micaela S Parker - [email protected]; Edward A Laws - [email protected]; Lorraine C Backer - [email protected]; Lora E Fleming - [email protected] • Corresponding author from Centers for Oceans and Human Health Investigators Meeting Woods Hole, MA. USA. 24-27 April 2007 Published: 7 November 200B Environmental Health 2008, 7(Suppl 2):S4 doi:10.1186/1476·069X·7·S2·S4 This article is available from: http://www.ehjournal.net/content/7/S2/S4 © 2008 Moore et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution. and reproduction in any medium. provided the original work is properly cited. Abstract Anthropogenically-derived increases in atmospheric greenhouse gas concentrations have been implicated in recent climate change, and are projected to substantially impact the climate on a global scale in the future. For marine and freshwater systems, increasing concentrations of greenhouse gases are expected to increase surface temperatures, lower pH, and cause changes to vertical mixing, upwelling, precipitation, and evaporation patterns. The potential consequences of these changes for harmful algal blooms (HABs) have received relatively little attention and are not well understood. Given the apparent increase in HABs around the world and the potential for greater problems as a result of climate change and ocean acidification, substantial research is needed to evaluate the direct and indirect associations between HABs, climate change, ocean acidification, and human health. This research will require a multidisciplinary approach utilizing expertise in climatology, oceanography, biology, epidemiology, and other disciplines. We review the interactions between selected patterns of large-scale climate variability and climate change, oceanic conditions, and harmful algae. Introduction result of human activities since 1750, and now far exceed Global atmospheric concentrations of carbon dioxide, pre-industrial values determined from ice cores spanning methane, and nitrous oxides have increased markedly as a many hundreds of thousands of years. Carbon dioxide Page 1 of 12 (page number not for citation purposes) Environmental Health 2008, 7(Suppl 2):S4 http://www.ehjournal.netcontent/7/S2/S4 (CO2) concentrations have increased from roughly 280 has been said of infectious disease that climate constrains ppmv in pre-industrial times to present day levels of ~380 the range and weather determines the timing and inten- ppmv, mostly due to fossil fuel burning and deforestation sity of outbreaks [14]. This is also likely applicable to [1]. The direct and indirect impacts of these increases in HABs. In this review, we summarize established climate greenhouse gas concentrations on the oceans will include impacts on the oceans and toxin-producing HA species, increasing temperatures, acidification, changes to the den- and discuss the implications for human health. Finally, sity structure of the upper ocean which will alter vertical directions for future research are provided. mixing of waters, intensification/weakening of upwelling winds, and changes to the timing and volume of freshwa- This paper does not aim to prove that anthropogenic cli- ter runoff into coastal marine waters, to name a few. mate change is responsible for the global outbreak of Indeed, evidence is emerging to suggest that some of these HABs [15]. Few examples in the literature have quantita- changes are already underway [2]. tively demonstrated this potential link; primarily because it is extremely difficult to separate the influence of climate The predicted changes in our oceans are likely to impact change (natural and anthropogenic) from other anthro- both directly and indirectly the interactions between pogenic impacts that are known to contribute to HABs humans and the oceans. Recent studies have reviewed using the limited datasets that are currently available. general oceanic responses to future climate change, while Nevertheless, evidence that climate change has influenced acknowledging the impacts that these changes will have the frequency, duration, and geographical range of HABs on human societies [3-5]. Likewise, over the past decade, is emerging as monitoring data temporally and spatially several studies have suggested possible relationships accumulates. Given the potential impact it is recom- between climate and the magnitude, frequency, and dura- mended that the influence of climate be considered and tion of harmful algal blooms (HABs) [6-11]. incorporated into future HAB research and monitoring efforts. The term "harmful" has been used to describe blooms of algae that can cause a range of deleterious physiological Discussion and environmental effects [12]. Some harmful algae (HA) Climate impacts on HABs produce potent natural toxins that are bioconcentrated by HA species comprise only a small component of the phy- some filter feeding shellfish and finfish, and passed along toplankton community, and their individual responses to the food chain causing illness or death if consumed by climate variation and change can differ from that of the humans or other organisms. Other HA are non-toxic, but phytoplankton community as a whole. In the ocean, the attain high biomass resulting in substantial reductions in most important HA and their poisoning syndromes (in biodiversity of the phytoplankton community structure parentheses) are diatoms from the genus Pseudo-nitzschia and the amount of light reaching the benthos [13]. The (amnesic shellfish poisoning), and species of dinoflagel- decomposition of senescent blooms can lead to serious lates from the genera Alexandrium, Pyrodinium, and Gym- reductions in dissolved oxygen concentrations. Because of nodinium (paralytic shellfish poisoning), Karenia the ecological and physiological diversities among HA (neurotoxic shellfish poisoning, and aerosolized Florida species (discussed below), their responses to the same red tide respiratory syndrome), Dinophysis and Prorocen- changes in climate will vary. trum (diarrhetic shellfish poisoning), and Gambierdiscus (ciguatera fish poisoning). In freshwater, the most impor- Few studies have used comprehensive datasets together tant HABs are caused by certain species of cyanobacteria with rigorous statistical analyses to confirm linkages (blue green algae) from the genera Anabaena, Microcystis, between climate and HABs. Even fewer have attempted to and Aphanizomenon (cyanobacterial poisoning) [16]. In include epidemiological information on HAB-related ill- both marine and freshwater systems, for humans and nesses. The aim of this paper is to provide a synopsis of other animals, exposure to HA toxins results from eating the current state of knowledge of climate impacts on contaminated fish or shellfish, drinking contaminated HABs and their known and potential consequences for water, inhaling contaminated aerosol, or by contacting human health, particularly as it relates to the main contaminated water. research themes of the NSF/NIEHS and NOAA Centers for Oceans and Human Health. It is generally accepted that HABs are increasing in fre- quency, intensity, and duration in all aquatic environ- We use the term "climate" here to refer to large-scale and ments on a global scale [17,18], and some of this may be low frequency patterns of climate variability, such as the due to changes in climate. However, relatively little work El Nino/Southern Oscillation, as well as anthropogenic has been done to characterize this link, and it is poorly climate change. This is opposed to "weather" events that understood [19-21]; primarily due to difficulty in separat- occur over much shorter timescales [i.e., days to weeks). It ing the influence of climate change (natural and anthro- Page 2 of 12 (page number not for citation purposes) Environmental Health 2008, 7(Suppl 2):S4 http://www.ehjournal.net/content/7/S2/S4 pogenic) from other anthropogenic