Assessing the response of the Great South Bay plankton community to Hurricane Sandy

Gobler, Christopher; Young, Craig; Goleski, Jennifer; Wallace, Ryan; Koch, Florian; Hattenrath-Lehmann, Theresa; Lusty, Mark; Thickman, Jake; Langlois, Kylie; Litvinenko, Yuriy; Collier, Jackie; Lonsdale, Darcy

The south shore of Long Island is lined by barrier islands that have been breached by ocean waters dozens of times during the past 300 years. On October 29th, 2012, Hurricane Sandy created a new ocean inlet in eastern Great South Bay (GSB) that has had a strong effect on bay circulation and salinity. This provides a description of the changes in GSB and Moriches Bay (an adjacent bay to the east) water quality and plankton communities related to the creation of the New Inlet and the spatial and temporal extent of those changes. Time series sampling was performed at multiple locales within GSB and Moriches Bay from 2013 through 2015 and horizontal mapping of temperature, salinity, dissolved oxygen, and chlorophyll a was performed. Historical comparisons using past water quality monitoring data from academic and municipal sources was also made. The New Inlet provides asymmetrical ocean flushing, exchanging strongly with waters to the east significantly more than with waters to the west. Plankton communities displayed a bifurcated response to the New Inlet. In locales north (Bellport Bay) and east (Narrow Bay, Moriches Bay) of the New Inlet, water residence times within the bay, summer water temperatures, total and dissolved nitrogen, chlorophyll a, diatoms, cryptophytes, and dinoflagellates significantly decreased, while salinity, dissolved oxygen, and water clarity significantly bincreased. In contrast, waters west of the New Inlet within the center of GSB experienced little change in residence times, significantly increased chlorophyll a, pennate diatoms, cryptophytes, heterotrophic bacteria, and pico-phytoplankton, including harmful brown tides (Aureococcus anophagefferens), cyanobacteria, and chlorophytes, and significantly decreased in water clarity and summer dissolved oxygen levels. The formation of the New Inlet created beneficial conditions within the bay regions close to the breach in terms of temperatures, water clarity, and phytoplankton abundance and diversity, which are likely conducive to improved growth and performance of key estuarine resources such as vital resources including zooplankton, bivalves, and seagrasses. Conversely, more frequent occurrences of brown tides and other algal blooms in central GSB may have been be due to the local effect of the breach or larger-scale changes in the ecosystem, and could have negative consequences for estuarine resource species. This information should be considered when determining the fate of current and future breaches along Long Island’s south shore barrier islands.

Assessing the response of the Great South Bay plankton community to Hurricane Sandy

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