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Fishery Bulletin 11 6(1) 
gested that pelagic Sargassurn macroalgae bloomed in 
the NERR, where they may have recirculated over an 
extended period of time, before being picked up by the 
North Brazil Current and transported to the eastern 
Caribbean region. In waters with elevated nutrients 
(Lapointe et ah, 2014), high salinities, high light inten¬ 
sities (low cloud cover), and sea-surface temperatures 
(SSTs) between 18°C and 30°C (Hanisak and Samuel, 
1987), pelagic species of Sargassurn are capable of rap¬ 
id growth (Lapointe, 1986; Hanisak and Samuel, 1987). 
Climate plays a major role in setting the physical 
hydrographic processes (Karnauskas et al., 2015) that 
act to transport, aggregate, or scatter pelagic Sargas- 
sum species, and it affects algal productivity through 
its influence on the position of the Intertropical Con¬ 
vergence Zone (ITCZ) (Franks et ah, 2011; Schneider et 
al., 2014; Franks et al., 2016). Climate in the Northern 
Hemisphere is influenced by oceanic and atmospheric 
modes of variability from the Atlantic Ocean (Mehta et 
al., 2000; Sutton and Hodson, 2005) and Pacific Ocean 
(Wang and Fu, 2000). The Atlantic Multidecadal Os¬ 
cillation (AMO) represents below (cold AMO [AMOc]) 
and above (warm AMO [AMOw]) normal SST across 
the North Atlantic Ocean from 0°N to 70°N latitude 
(Enfield et al., 2001) and has a characteristic period¬ 
icity of around 65-80 years (Kerr, 2000; Gray et al., 
2004). The North Atlantic Oscillation (NAO) is associ¬ 
ated with an oscillation in the sea-level air-pressure 
gradient between Iceland and the Azores (Hurrell and 
Van Loon, 1997). The NAO displays negative (NAOn) 
and positive (NAOp) phases and responds to the effects 
of different physical processes on seasonal to multi¬ 
decadal time scales (Hurrell et al., 2003). The El Nino- 
Southern Oscillation (ENSO) is the quasiperiodic (2-7 
years) warming or cooling of the eastern equatorial 
Pacific Ocean (Walker, 1924; Bjerknes, 1969; Lighthill, 
1969; Godfrey, 1975; McCreary, 1976) with the shift 
of southeast trade winds over the central and west¬ 
ern Pacific Ocean (Krueger and Winston, 1975; Wyrtki, 
1975; McPhaden, 1999). The warm phase of the ENSO 
(ENSOw) is referred to as El Nino and the cool phase 
(ENSOc) is referred to as La Nina. The phase between 
ENSOc and ENSOw is referred to as neutral (ENSOn). 
The ENSO phases are identified by the SST anomaly 
from the Nino 3.4 region (5°S-5°N and 120°W-170°W) 
in the equatorial Pacific Ocean. 
Phases of the NAO (Seager et al., 2000) and ENSO 
(Giannini et al., 2001) contribute to the annual vari¬ 
ability of SST and winds in the tropical Atlantic Ocean 
that is measured with an index called the Atlantic Me¬ 
ridional Mode (AMM). These weather-related hydro- 
graphic characteristics in the tropical Atlantic Ocean 
affect the position and strength of the thermal equator 
and hence the position and strength of the ITCZ with 
its heated, rising air. The ITCZ is an area where the 
northeast and southeast trade wind systems meet cre¬ 
ating a rain band in the tropical North Atlantic Ocean 
(Vimont and Kossin, 2007). The position of the ITCZ 
directly affects hydrographic characteristics in neritic 
waters of West Africa, northeast Brazil, and Central 
America and has been associated with variability in 
rainfall over West Africa (Lamb, 1978; Janicot et al., 
1998; Sultan and Janicot, 2000), northeast Brazil (Has- 
tenrath and Heller, 1977; Uvo et al., 1998; Robertson et 
al., 2004), and Central America (Giannini et al., 2000; 
Taylor et al., 2002). The ITCZ is important because it 
affects the cross-equatorial transport of heat and salin¬ 
ity by upper-level ocean currents (Berger and Wefer, 
1996; Maslin et al., 1997; Vink et al., 2002) and the 
strength of the Loop Current (LC), a northward flow¬ 
ing current that enters the Gulf of Mexico (GOM) from 
the Caribbean Sea (Niirnberg et al., 2008). The LC 
connects the Yucatan Channel and Straits of Florida 
(Hurlburt and Thompson, 1980; Oey et al., 2005) and 
there is a significant link between the intrusion of the 
LC into the GOM and the estimated transport of the 
Florida Current (Lin et al., 2010) at low frequencies 
(time scales longer than 120 days; Lin et al., 2010). 
The northward intrusion of the LC can extend as far as 
the Mississippi River Delta and the Florida continental 
shelf (Huh et al., 1981; Wiseman and Dinnel, 1988). 
This intrusion deflects Mississippi River discharge 
westward with hydrographic conditions in surface wa¬ 
ters of the northeastern GOM approaching those of the 
Caribbean Sea (high salinity and SST) (Niirnberg et 
al., 2008). 
Phases of the AMO and NAO affect moist-air-related 
wind patterns in the GOM. In the summer, under the 
AMOc phase, the Bermuda High is strengthened and 
its associated easterly and southeasterly low-level jets 
can extend well over the warm waters of the Caribbean 
region. These jets, transport moist air westward along 
the GOM (Wang et al., 2006; Hu and Feng, 2007). Dur¬ 
ing the NAOp phases, low geopotential heights and 
high SST levels are set along the GOM, bringing south¬ 
erly winds in winter over south Florida, and in spring 
over south Florida and the Florida panhandle (Hurrell 
and Deser, 2009). 
Pelagic species of Sargassurn often accumulate 
in mats and windrows (lines of floating Sargassurn 
caused by wind, tide or currents) to form a structured 
habitat and a source of food and refuge for a rich and 
diverse assemblage of fish and invertebrates (Dooley, 
1972; Bortone et al., 1977; Butler et al., 1983; Coston- 
Clements et al., 1991; Comyns et al., 2002; Wells and 
Rooker, 2004; Hoffmayer et al., 2005). Habitat of Sar- 
gassum species was declared essential fish habitat in 
the U.S. South Atlantic region in 2002 (SAFMC, 2002), 
and management measures were implemented by the 
National Marine Fisheries Service (NMFS) in 2003. 
Seasonal and yearly differences in the abundance and 
distribution of pelagic Sargassurn could contribute to 
the variation observed in recruitment of marine fishes 
and other marine organisms (Butler et al., 1983). In 
spite of the importance of Sargassurn as habitat, few 
studies have examined the effect of climate regimes 
on the occurrence of species of pelagic Sargassurn over 
decadal and interannual time scales. 
The Southeast Area Monitoring and Assessment 
Program (SEAMAP) is a federal and state cooperative 
