MEPS 520:165-173 (2015)  -  DOI: https://doi.org/10.3354/meps11104

Seagrass consumption by native and a tropically associated fish species: potential impacts of the tropicalization of the northern Gulf of Mexico

K. L. Heck Jr.1,2,*, F. J. Fodrie3, S. Madsen4, C. J. Baillie5, D. A. Byron

1Dauphin Island Sea Lab, Dauphin Island, AL 36528, USA
2University of South Alabama, Mobile, AL 36688, USA
3Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC 28557, USA
4Atlantic States Marine Fisheries Commission, Arlington, VA 22201, USA
5Marine Science Center, Northeastern University, Nahant, MA 01908, USA
*Corresponding author:

ABSTRACT: Temperatures are rising in most temperate and polar environments, and a well-documented effect of this change is a poleward range shift by a wide variety of terrestrial and aquatic species. In the northern Gulf of Mexico (GOM), an increasing number of tropical species have recently become established among the extant warm-temperate fauna. These include a diversity of tropical fishes, manatees, green turtles, warm-water corals, and black mangroves. The impact of these species may be profound, primarily because temperate species are restricted from shifting northward by the North American land mass. Thus, as tropical species expand northward in the GOM, they must interact with the extant species and potentially compete for essential resources or become prey for each other. Here we focus on tropical immigrants capable of transforming the vast and highly productive seagrass systems of the northern GOM, emphasizing herbivorous parrotfishes and comparing their impact with endemic seagrass-resident fishes. Increased numbers of these herbivores (plus green turtles and manatees) would likely shift detritus-based food webs in seagrass meadows to webs dominated by direct consumption of seagrasses. We provide estimates of some expected consumption rates and effects of these tropically associated seagrass herbivores and predict that the consequences of the increased tropicalization of northern GOM seagrass meadows will be: substantially reduced standing crops and structural complexity of seagrass meadows; increased energy flux through grazing food webs; and a greatly reduced nursery role that will result in much smaller adult populations of those finfish and shellfish species that rely on seagrasses as nurseries.


KEY WORDS:Nicholsina usta · Lagodon rhomboides · Stephanolepis hispidus · Range shift · Climate change · Thalassia testudinum · Halodule wrightii · Herbivory


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Cite this article as: Heck KL, Jr , Fodrie FJ, Madsen S, Baillie CJ, Byron DA (2015) Seagrass consumption by native and a tropically associated fish species: potential impacts of the tropicalization of the northern Gulf of Mexico. Mar Ecol Prog Ser 520:165-173. https://doi.org/10.3354/meps11104

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