Abstract

Since the 1970s, benthic macroalgae have increased in abundance on Caribbean coral reefs in response expand-ing human activities and land-based nutrient pollution. Several species of benthic and Sargassum have responded to the increased nutrient subsidies. For example, extensive meadows Sargassum hystrix and Sargassum polyceratium have replaced hermatypic corals on fringing reefs the north coast of Jamaica (Lapointe 1997, Lapointe et al. 2011) and southwest Martinique (Littler et 1992). In 2011, unprecedented high-biomass strandings of pelagic Sargassum began to impact waters throughout the Caribbean, resulting in fish kills, dead zones, human health issues, and impacts to the regional tourist-based economies (Hu et al. Biogeochemical studies along offshore gradients, combined with experimental nutrient enrichment indicate that elevated nitrogen (N) and phosphorus (P) availability from expanding human activities is major factor supporting enhanced productivity, growth and reproduction of both benthic and Sargassum (Lapointe, 1995, Lapointe, 1997, Lapointe et al., 2011, Lapointe et al., 2014). Pelagic could also be responding to nutrient enrichment in upstream waters in the Gulf of Mexico: (C:N:P) data indicate that high N:P discharges from the Mississippi Atchafalaya rivers contributed to blooms of pelagic Sargassum in the Gulf of Mexico that occurred 2011 through 2015 (Lapointe et al., This study compared the tissue nutrient content of three benthic Sargassum species pteropleuron, Sargas-sum polyceratium, and Sargassum filipendula) and two pelagic species fluitans and Sargassum natans) in Florida. We hypothesized that the benthic species would have a tissue nutrient content than the pelagic species due to their closer proximity to land-based pollution. Additionally, the pelagic species would have higher tissue nutrient

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