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Maryland Studies: Geographic and Temporal Patterns
Maryland Studies: Geographic and Temporal Patterns

The Outer Continental Shelf offshore of Maryland provides important habitat for marine wildlife over the course of the year. Each season brings a unique shift in habitat characteristics and with it a new array of species reliant on the specific resources available. Despite seasonal variation, however, nearshore areas showed persistent patterns of high species richness and abundance year-round.

Download Wildlife Studies Offshore of Maryland. This 8-page summary publication represents an overview of results from the final technical report for the Maryland-focused study, and features survey results and case studies on marine mammals, sea turtles, and wintering seabirds. The Executive Summary for the technical report is also available here.

Additional results and case studies can be found in the 32-page synthesis report for the mid-Atlantic regional study, Mid-Atlantic Wildlife Studies: Distribution and Abundance of Wildlife along the Eastern Seaboard, 2012-2014.

 

Persistent Patterns

Several taxa showed persistent hotspots of abundance with the Maryland study area, including Red-Throated Loons, Common Loons, Northern Gannets, storm-petrels, alcids, gulls and terns, rays, sea turtles, and dolphins. In general, many species exhibited a nearshore distribution, concentrated within about 30 km of shore. Species most commonly seen offshore included alcids, sea turtles, and Wilson’s Storm-Petrels.

Areas near the mouths of Chesapeake Bay and Delaware Bay showed high species diversity and relative abundance throughout the year. These areas had high primary productivity relative to the rest of the mid-Atlantic region. Since primary productivity supports the pelagic ecosystem, these locations likely provided important and reliable foraging habitat for many species. Ocean waters off Maryland’s northern coast, within roughly 20-30 km of shore, were also a consistent hotspot for many taxa, which may have been partially driven by the density of nearshore surveys in this area.

 

Persistent Hotspots

These maps highlight areas where the greatest number of species (left) and the greatest number of individuals across all taxa (right) were consistently observed over the course of the study.
These maps highlight areas where the greatest number of species (left) and the greatest number of individuals across all taxa (right) were consistently observed over the course of the study.
These maps highlight areas where the greatest number of species (left) and the greatest number of individuals across all taxa (right) were consistently observed over the course of the study.
 
Temporal changes in relative abundance for major taxonomic groups. Data are from the boat-based surveys (green, left) and high resolution digital video aerial surveys (brown, right) conducted in 2012-2014. Species included in each category are listed in Williams et al. (2015). Labels refer to seasons in the Northern Hemisphere. *Forage fish were counted as schools, not as individuals, unlike the other animal groups.
Temporal changes in relative abundance for major taxonomic groups. Data are from the boat-based surveys (green, left) and high resolution digital video aerial surveys (brown, right) conducted in 2012-2014. Species included in each category are listed in Williams et al. (2015). Labels refer to seasons in the Northern Hemisphere. *Forage fish were counted as schools, not as individuals, unlike the other animal groups.
 

Seasonal Patterns

During spring and fall migration, a variety of taxa use this region. Many of these species are also part-time or year-round residents that use the area for foraging during the breeding season, or for foraging, roosting, and other activities during nonbreeding periods.

Fall: Seabird species composition shifted as summer residents, such as terns, shearwaters, and storm-petrels, migrated south. Winter residents, such as Northern Gannets, Red-throated Loons and Common Loons, and scoters migrated into the study area. Songbirds, shorebirds, Eastern Red Bats, and Peregrine Falcons migrated over the ocean through the study area. Cownose Rays were seen in dense migratory aggregations. Schools of forage fish were seen along the coast, especially off of Maryland. Sea turtles and Bottlenose Dolphins remained through late fall, while Common Dolphins arrived in November. 

Winter: Avian abundance was highest offshore of Maryland during winter. Seabirds occupied habitat throughout the regional study area, with variations in distribution patterns among species. Northern Gannets were broadly distributed across the study area, while scoters were concentrated nearshore especially near the mouths of the bays. Small numbers of alcids and baleen whales were observed across the area. Common Dolphins were most abundant in this season, while most Bottlenose Dolphins and sea turtles left the study area. 

Spring: Wintering seabirds migrated out of the regional study area, while summer resident seabirds arrived. Bottlenose Dolphins and sea turtles also began to arrive in the study area. Songbirds, shorebirds, and raptors migrated over the ocean across the region. 

Summer: Overall abundance of avian species was lowest in the Maryland study area during the summer, though federal and state-listed species were observed in nearshore regions, including Roseate Terns, Least Terns, Common Terns, and Royal Terns. Nonbreeding species, such as storm-petrels, were broadly distributed across the continental shelf. Large numbers of Cownose Rays migrated through the study area early in the season. Sea turtles and Bottlenose Dolphins were most abundant during the summer.

 

For More Information

For more information, see Chapters 2, 5, 7, 9, 11, 12, 13, and 14 in the technical report.
 
Photo Credits: Header photo © Kate Sutherland
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