According to the U.S. Global Change Research Program S Draft National Climate Assessment (2013)

1. Global concentrations of green house gases (GHG) due to human activities are on the increase. Atmospheric concentrations of carbon dioxide, methane, and nitrous oxide, all have increased to much higher levels than those present during pre-industrial times (Moore et al. 2008). Between 1970 and 2004, GHG increased by 70% and the IPCC (Intergovernmental Panel on Climate Change) Special Report on Emissions Scenarios projects a further increase of global GHG emissions by 25 to 90% between the years 2000 to 2030 (IPCC 2007).

Moore SK, Trainer VL, Mantua NJ et al (2008) Impacts of climate variability and future climate change on harmful algal blooms and human health. Environ Health 7:S4. doi:10.1186/1476-069X-7-S2-S4

According to the U.S. Global Change Research Program’s Draft National Climate Assessment (2013):

“Average US temperature has increased by about 1.5°F since 1895; more than 80% of this increase has occurred since 1980. The most recent decade was the nation’s hottest on record. Though most regions of the U.S. are experiencing warming, the changes in temperature are not uniform. In general, temperatures are rising more quickly at higher latitudes, but there is considerable observed variability across the regions of the U.S.”

2.Since 1970, average annual air temperatures in the southeastern region of the United States have increased by more than 1oC (Global Climate Change Impacts in the United States 2009).

Global Climate Change Impacts in the United States (2009) Karl TR, Melillo JM, and Peterson TC (eds). Cambridge University Press, Cambridge, UK

3.Throughout the year, large amounts of African dust are carried by wind to the western Atlantic (including Florida’s coast) and the Caribbean. The amount of dust being transported is highly correlated with amounts of rainfall in Africa (Prospero and Lamb 2003). The deposition of Saharan minerals from this dust are thought to be used by diazotrophic or nitrogen fixing bacteria to fuel the nitrogen economy of red tides (Walsh and Steidinger 2001), triggering large blooms. Dust particles are known to affect a number of other processes as well, including cloud formation, precipitation, propagation of drought, solar radiation, pollution scavenging, ozone concentrations. There even appears to be a link between Atlantic tropical cyclone activity and Saharan dust (Prospero and Lamb 2003; Evans et al.2006). The IPCC (2007) has concluded that dust could play an important role in climate change. Prospero and Lamb (2003) stated that “because of the sensitivity of dust emissions to climate, future changes in climate could result in large changes in emissions from African and other arid regions that, in turn, could lead to impacts on climate over large areas.”

Evans AT, Dunion J, Foley JA, Heidinger AK, Velden CS (2006) New evidence for a relationship between Atlantic tropical cyclones activity and African dust outbreaks. Geophysical Res Lett 33

Prospero JM, Lamb PJ (2003) African drought and dust transport to Caribbean: climate change implications. Science 302:1024-1027

Walsh JJ, Steidinger KA (2001) Saharan dust and Florida red tides: the

cyanophyte connection. Journal of Geophysical Research—Oceans 106,11,597–11,612

4.Mortality due to storm events and tidal stranding has also been documented for other sirenian species (dugongs; Heinsohn and Spain 1974; Marsh 1989).

Heinsohn GE, Spain AV (1974) Effects of tropical cyclone on littoral and sub-littoral biotic communities and on a population of dugongs (Dugong dugong [Müller]). BiolConserv 9:21-23

Marsh H (1989) Mass strandings of dugongs by a tropical cyclone in northern Australia. Mar MammSci 5:78-8

5.The number of calves sighted on surveys declined over the next few years (from 22% in 1988 to 1.5% in 1994; Marsh and Corkeron 1997) suggesting that the impact of habitat loss may last several years.

Marsh H, Corkeron P (1997) The status of the dugong in the Great Barrier Reef Marine Park. In State of the Great Barrier Reef World Heritage Area. Proceedings of a technical workshop held in Townsville, Queensland, Australia, 27–29 November 1995. Workshop Series 23, D. Wachenfeld, J. Oliver and J. Davis (Eds), Great Barrier Marine Park Authority, 17 pp. Available at <

The negative impact on dugong life history from the loss of coastal seagrass associated with exceptionally high rainfall and other extreme weather events is of major concern to scientists given the potential effects of climate change on dugongs (Sobtzick et al. 2012).

Sobtzick S, Hagihara R, Grech A, Marsh H (2012) Aerial survey of the urban coast of Queensland to evaluate the response of the dugong population to the widespread effects of the extreme weather events of the summer of 2010-11. Final report to the Australian Marine Mammal Centre and the National Environmental Research Program 63 p

6.According to Laist and Reynolds (2005a ,b) coastal water temperatures throughout Florida routinelyfall below 17–18ºC (61–64ºF) for at least short periods in winter. Even in southernmost Florida they can remain below those levels for twoweeks at a time and briefly dip to as low as 10ºC (50ºF) in severe winters. Even in southernmost Florida minimum winter water temperatures of 14°C and 13°C at Miami and Key West were recorded.

Laist DW, Reynolds JE III (2005) Florida manatees, warm-water refuges, and the uncertain future. Coast Manag 33:279-295

Laist DW, Reynolds JE III (2005) Influence of power plants and other warm-water refuges on Florida manatees. Mar MamSci 21:739-764

7.Very cold temperatures were recorded in all parts of Florida, and manatees died of cold exposure in large numbers in the central and southwestern parts of the state. However, deaths occurred as far south as the Florida Keys (Barlas et al. 2011).

Barlas ME, Deutsch CJ, de Wit M, Ward-Geiger LI (eds) (2011) Florida manatee cold-related unusual mortality event, January-April 2010. Final report to USFWS (grant 40181AG037). Florida Fish and Wildlife Conservation Commission, St. Petersburg, FL. 138 p

8.Manatee synoptic surveys are ad hoc censuses, designed to cover areas were manatees are likely to occur during winter. Because counts are neither systematic nor random, and there are no statistical estimates of variance or bias (surveys do not account for incomplete or heterogeneous detection),they do not estimate or index true population size (Edwards et al. 2007, Fonnesbeck et al. 2009). Laist et al. (2013) report synoptic counts as they relate to manatee aggregation sites.

Edwards HH, PollockKH, AckermanBB, Reynolds JE III, JA Powell (2007)Estimation of detection probability in manatee aerial surveys at a winter aggregation site. JWildl Manage 71: 2052-2060

Fonnesbeck CJ, EdwardsHH, Reynolds JE III (2009) A hierarchical covariate model for detection, availability and abundance of Florida manatees at a warm water aggregation site. In Thomson, DL, Cooch, EG, Conroy, MJ (Eds.) Modeling Demographic Processes in Marked Populations Series: Environmental and Ecological Statistics, Vol. 3, Springer, pp 563-578.

Laist DW, Taylor C, Reynolds III JE.2113. Winter Habitat Preferences for Florida Manatees and Vulnerability to Cold. PLoSONE8(3):e58978. doi:10.1371/

journal.pone.0058978

9.Several of the power plants at which manatees aggregate have under-gone, or arein the process of repowering which could extend their lifein their current location for 30 to 40 or more years(if equal to their predecessor’s lifespan). After repowering, these plants continue to discharge water warmer than ambient suitable for manatees in winter. Climate change, particular sea-level rise and increased intensity of storms, could potentially interrupt the operation of these plants, and consequently impact the manatees that depend on them.

10.According to the Southwest Florida Water Management District (SWFWMD), anecdotal reports from the monitoring of several springs over several decades in northwest Florida indicate that spring discharge has decreased in recent years (SWFWMD 2001).Fluctuations in the average annual discharge at monitored springs has occurred seasonal and annually over the last 30 years. Fluctuations may have resulted from variations in rainfall, ground-water withdrawals, or a combination of both (SWFWMD 2001).

SWFWMD (Southwest Florida Water Management District) (2001) Hydrology and water quality of select springs in the Southwest Florida Water Management District. Prepared by the Water Quality Monitoring Program 148 p

11.Fifteen percent of the manatees counted in 2010 used two spring systems, Blue Spring in Volusia County and Crystal River, Citrus County

12.Spring flow in Wakulla Spring, a location currently used by manatees in winter, has ncreased in part due to changes in sea level, and as a result of an increase in groundwater withdrawal (Chelette et al. 2002; Kulakowski 2010).

Chelette A, Pratt TR, Katz BG (2002) Nitrate loading as an indicator of nonpoint source pollution in the lower St. Marks-Wakulla Rivers watershed. Northwest FloridaWater Management District.Water Resources Special Report 02-1.

Kulakowski ZP (2010) Chromophoric dissolved organic carbon loading of five intermittent streams recharging Wakulla Springs, Florida. M.S. Thesis, Florida State University, Tallahassee, Florida

13.According to Florida’s Office of Economic and Demographic Research (2012) Florida’s human population is projected to grow by nearly 4.5 million by 2030. Many of those people will live along the coasts.

Office of Economic and Demographic Research (2012) Demographic Estimating Conference, Florida Demographic Forecast.

14.Depending on their size and the time of year, a manatee can consume about 7% (adults) to 16% (juveniles) of its body weight per day (~45 kg of forage/day; Etheridge et al. 1985). Gut-content analysis of 84 manatees recovered from different areas of Florida found that they consumed 23 different species of plants; however, 77% of the vegetation analyzed represented only eight species (Ledder 1986).

Etheridge K, Rathbun GB, Powell JA, Kochman HI (1985) Consumption of aquatic plants by the West Indian Manatee. J Aquat Plant Manage 23:21-25

Ledder DA (1986) Food habits of the West Indian manatee, Trichechusmanatuslatirostris, in South Florida. MS thesis, University of Miami, FL

15.Unlike temperate terrestrial plant species, there are no other, more adaptive seagrass species, waiting to fill open niches or expand their ranges to replace those affected by climate change. Florida’s seagrass composition is very similar to that found in the Caribbean and other tropical regions, with Halodulewrightii and Thalassiatestudinum (which comprise a large part of manatee diets) dominating pioneer and climax vegetation communities respectively. The climax species Thalassia is slow growing, long lived, and requires high light levels.

Green EP, Short FT (2003) World Atlas of Seagrasses. Prepared by the UIMEP World ConservationMonitoring Centre. U of CA Press, Berkeley, USA

16.Increases in temperature and salinity also could have direct effects on seagrass flowering and germination time (de Cock 1981; McMillan 1982; Durako and Moffler 1987), which are especially important for species that require specific temperature and salinity regimes for reproduction. Increases in water temperature as a result of GCC are expected to increase the frequency of eutrophication in estuarine ecosystems. Under eutrophic conditions, algal species often out-compete local seagrasses, and the magnitude and extent of algal competition may strongly depend on water temperature (Neckles et al. 1993). For example, algal epiphytes are known to affect the productivity of seagrasses by limiting the amount of light and carbon available to the plant. High water temperatures can exacerbate the effects of algal epiphytes on the seagrasses and could potentially eliminate some species of grass from local communities (Sand-Jensen, 1977; Sand-Jensen and Revsbech 1987).

de Cock, AWAM (1981) Influence of temperature and variation in temperature on flowering in Zostera marina under laboratory conditions. AquatBot 10:125-132

McMillan C (1982) Reproductive physiology of tropical seagrasses. AquatBot 14:245-258

Durako MJ, Moffler MD (1987) Factors affecting the reproductive ecology of Thalassiatestudinumhydrocharitaceae. AquatBot 27:79-96

Neckles HA, Wetzel RL, Orth RJ (1993) Relative effects of nutrient enrichment and grazing on epiphytemacrophyte (Zostera marina L.) dynamics.Oecologia 93:285-295

Sand-Jensen, K (1977) Effects of epiphytes on eelgrass photosynthesis.AqutBot 3:55-63

Sand-Jensen, K, Revsbech NP (1987) Photosynthesis and light adaptation in epiphyte-macrophyte associations measured by oxygen microelectrodes.LmnolOceanogr 32:452

17.UV-B exposure is known to have a negative impact on the photosynthetic capacity of seagrass (Trocine et al. 1982), inhibiting its growth. Its effects will be greatest on shallow water plants that are more readily exposed to radiation (Short and Neckles 1999).

Trocine RP, Rice JD, Wells GN (1982) Photosynthetic response of seagrass to UV-A radiation and the influence of visible light intensity. Plant Physiol 69:341-344

Short FT, Neckles HA (1999) The effects of global climate change on seagrasses. Aqua Bot 63:169-196

18.Climate change is likely to impact all sirenian species in some way. For example the impacts to terrestrial habitatsfrom climate change will most likely be felt by manatees and dugongs world-wide. For example the Amazon rainforest has experienced increases in drought conditions induced by climate change. Extensive droughts in the Amazon could isolate manatees for extended periods, and lead to increases in manatee mortality (Marsh et al. 2011). Hydrologic changes in Africa are also likely to impact habitats used by African manatees, and dugongs are known to be impacted by increases in storms and flooding(Marsh et al. 2011).

Changes towater control structures, or increasing numbers of them due to changes in climate, may inhibit migration or movements of manatees, especially those species that primarily inhabit rivers (Robinson et al. 2005). The water control structures themselves are known to cause direct mortality (Odell and Reynolds 1979).

Increases in subsistence hunting of sirenian species may increase as food resources needed by human populations become limited (Marsh et al. 2011, Würsig et al. 2002).

Manatees and dugongs worldwide may come under ecologicalpressure from competition from other aquatic herbivores for limited food resources (Robinson et al. 2005).

Red tide blooms (like those in the Gulf of Mexico) brought on by warmer and drier climates, dust transport, and eutrophication could because more prevalent, potentially impacting other sirenian species (Marsh et al. 2011).

Other impacts of GCC on sirenian populations are possible (Marsh et al. 2011, Robinson et al. 2005, Würsig et al 2002.

Marsh H, O’Shea TJ, Reynolds RE, III (2011) Ecology and conservation of the sirenia, dugongs and manatees. Cambridge University Press, New York

Odell DK, Reynolds RE, III (1979) Observations of manatee mortality in south Florida. J Wild Mang 43:572-577

Robinson RA, Learmonth JA, Hutson AM et al (2005) Climate Change and Migratory Species. A report for Defra Research Contract CR0302,

Würsig, B. Reeves RR, Ortega-Ortiz JG (2002) Global Climate Change and Marine Mammals. In: Evans PGH and Raga JA (eds) Marine Mammals: Biology and Conservation. Kluwer Academic/Plenum Publishers, NY pp 589-608

19.Pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, and in some cases, these factors can actually facilitate the increase in pathogen development and survival, disease transmission, and host susceptibility (Harvell et al. 2002; Harvell et al. 2009).

Harvell CD, Mitchell CE, Ward JR, et al (2002) Climate change and wildlife disease risks for terrestrial and marine biota. Science 296:2158-2162

Harvell D, Altizer S, Cattadori IM, Harrington L, Weil E (2009) Climate change and wildlife diseases: when does the host matter most? Ecology 90:269-279

20.According to Martin et al. (2009), structured decision making (SDM) provides a rigorous framework that promotes logical and transparent decision making that may help facilitate the adaptation process (Martin et al. 2009, 2011). SDM is a formal method for analyzing a decision by breaking it into components to help identify the optimal decision based on the intended objectives (Clemen and Reilly 2001). Based on decision theory, these methods provide a powerful framework for making decisions concerning complex systems.

According to Martin et al. 2011, SDM would be a useful application for manatee conservation as it relates to climate change since adaptation may proceed through direct management actions to maintain or improve survival and reproduction, or through actions to modify, improve, or maintain critical aquatic habitat expected to be affected by climate change (Martin et al. 2011). Such an approach may help manatees have the best chance of adapting to climate in a changing world. Implementation of SDM is one way for managers to begin to identify the most prudent means of addressing the deleterious impacts of climate change on the Florida manatee population.

Clemen RT, Reilly T (2001) Making hard decisions with decision tools (2001) Duxbury Press, Pacific Grove, California

Martin J, Runge MC, Nichols JD, Lubow BC, Kendall WL (2009) Structured decision making as a conceptual framework to identify thresholds for conservation and management. Ecol Appl 19:1079-1090

Martin J, Fackler PL, Nichols JD et al (2011) Structured decision making as a proactive approach to dealing with sea level rise in Florida.Clim Chang 107:185-202