Alternate Title

An Aggregation of the Pandalid Shrimp, Heterocarpus ensifer, on Deep Reef Habitats of the West Florida Slope, Eastern Gulf of Mexico

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Heterocarpus ensifer A. Milne—Edwards (1881) (Crustacea: Pandalidae), armed nylon shrimp, is widely distributed in the western and eastern North Atlantic Ocean. In the western Atlantic this shrimp occurs from off North Carolina to Brazil and in the Gulf of Mexico (GOM), western Bahamas, and Caribbean Sea at depths of 170—885 m. Despite its widespread occurrence, ecology or biology information for this species are sparse, and in situ observations of abundance, behavior and habitat preferences are particularly lacking. During extensive submersible and ROV observations on and near deep—reefs in the north—central and eastern GOM, a remarkably large aggregation of H. ensifer was observed on the West Florida Slope (WFS). On one ROV dive it was estimated that thousands of these shrimp occupied an area m2. They were most abundant on transition (near reef) and prime high—profile reef habitats composed of dead and live Desmophyllum pertusum, sponges, rocks, and other coral species. Collected males (n=14) exhibited a broader size range, 17.74—33.72 mm CL, than females (n=12, 23.08— 30.15 mm CL); however, mean carapace length was similar for both sexes at 27.47 mm (females) and 26.40 mm (males). All but 3 collected females were ovigerous with Stage 1 embryos, and ROV video revealed that many of the shrimp were ovigerous females with clearly visible dark blue embryo masses on the abdomen. Evidence supports that the purpose of this aggregation was likely for mating and spawning. Although the frequency and locations of such aggregations are unknown, they are further indication of the importance of deep—sea complex habitats.

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Artificial Intelligence (AI) Use Statement

No artificial intelligence (AI) was used in the preparation of this manuscript