Long Island's estuaries, including the Great South Bay and Peconic Bay, are where freshwater rivers meet the Atlantic Ocean. These brackish environments create incredibly productive ecosystems that serve as nurseries for countless marine species. The salt marshes along the South Shore act as natural filters and storm buffers, while supporting unique communities of cordgrass, fiddler crabs, and diamondback terrapins.
Key Species
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Blue Crab
Callinectes sapidus
A commercially important species that thrives in the brackish waters of Long Island's bays. They can tolerate a wide range of salinities.
Adaptations: Special gills that can regulate salt intake; paddle-shaped rear legs for swimming
Role: Both predator and prey; important in nutrient cycling
Local importance: Supports recreational and commercial fisheries in Great South Bay
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Striped Bass
Morone saxatilis
An anadromous fish that migrates between fresh and salt water. Long Island's waters are critical to their Atlantic migration.
Adaptations: Can adjust kidney function to handle salinity changes; lateral line system detects prey
Role: Apex predator controlling populations of smaller fish
Local importance: Iconic sport fish; Long Beach and Montauk are famous striper destinations
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Spartina (Cordgrass)
Spartina alterniflora
The dominant plant of salt marshes, its roots stabilize sediments and its decomposing matter feeds the detrital food web.
Adaptations: Salt glands excrete excess salt; aerenchyma tissue allows oxygen to reach roots in waterlogged soil
Role: Foundation species; creates habitat structure and processes nutrients
Local importance: Critical for shoreline protection against storms and erosion
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Diamondback Terrapin
Malaclemys terrapin
The only turtle species in North America that lives exclusively in brackish water. Found in Jamaica Bay and along the South Shore.
Adaptations: Specialized salt glands near eyes; can drink brackish water that would dehydrate other reptiles
Role: Controls snail and crab populations; prey for raccoons and birds
Local importance: Species of special concern in NY; nesting habitat is threatened
🔬 Key Ecological Concepts
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Salinity Gradient: Estuaries create a continuum from fresh to salt water. Different species occupy different zones based on their osmoregulatory abilities. This stratification creates distinct microhabitats.
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Detrital Food Web: Unlike ocean food webs based on phytoplankton, estuarine food webs largely depend on decomposing marsh plants. Bacteria and fungi break down cordgrass, which is then consumed by small invertebrates.
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Nursery Function: Over 75% of commercially important fish and shellfish species use estuaries at some point in their life cycle, often as juveniles seeking shelter and abundant food.
Sandy Beaches & Dunes
Long Island's South Shore barrier beaches, including Jones Beach, Fire Island, and Long Beach, represent a dynamic environment constantly shaped by waves, wind, and storms. Despite appearing barren, these beaches host a surprising diversity of life adapted to shifting sands, salt spray, and extreme temperature changes. The dune systems behind the beaches provide critical habitat for nesting shorebirds and unique plant communities.
Key Species
🐚
Atlantic Surf Clam
Spisula solidissima
Burrows in the surf zone, filter feeding on phytoplankton. One of the largest clams on the Atlantic coast.
Adaptations: Powerful muscular foot for rapid burrowing; siphons extend to surface to feed and breathe
Role: Filter feeders that improve water quality; food source for gulls and rays
Local importance: Commercial harvesting occurs offshore; shells wash up on beaches
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Mole Crab (Sand Flea)
Emerita talpoida
These small crustaceans live right in the swash zone, burrowing backward into sand as each wave recedes.
Adaptations: Egg-shaped body perfect for burrowing; feathery antennae filter food from receding waves
Role: Key food source for shorebirds and fish; indicator species for beach health
Local importance: Abundant on Long Beach and Jones Beach; excellent fishing bait
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Piping Plover
Charadrius melodus
A threatened shorebird that nests directly on sandy beaches. Fire Island and other barrier beaches are critical nesting habitat.
Adaptations: Cryptic coloration matches sand; "broken wing" display to distract predators from nest
Role: Indicator of beach ecosystem health; controls invertebrate populations
Local importance: Beach sections are closed during nesting season to protect this federally threatened species
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Horseshoe Crab
Limulus polyphemus
A living fossil that spawns on Long Island beaches in late spring. Not actually a crab—more closely related to spiders.
Adaptations: Book gills for breathing; compound eyes with 1,000 receptors; blue copper-based blood
Role: Eggs are critical food for migrating shorebirds; predators include loggerhead turtles
Local importance: Their blood contains LAL, used to test medical equipment for bacteria; spawning monitored at local beaches
🔬 Key Ecological Concepts
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Zonation: Sandy beaches are divided into distinct zones: the dune, high beach (wrack line), mid-beach, and swash zone. Each zone has different moisture, temperature, and disturbance levels that support different species.
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Interstitial Community: Between sand grains lives a microscopic world of bacteria, protists, and tiny invertebrates called meiofauna. This community processes nutrients and forms the base of the beach food web.
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Barrier Island Dynamics: Long Island's barrier beaches migrate and change constantly. Overwash during storms moves sand landward, while longshore drift moves sand along the coast. Human structures often disrupt these natural processes.
Rocky Intertidal Zone
While less common than sandy shores, rocky intertidal habitats exist along Long Island's North Shore and at locations like Montauk Point. These areas are characterized by dramatic zonation patterns, where organisms sort themselves by their tolerance to exposure during low tide. The rocks provide hard substrate for attachment, creating three-dimensional habitat structure that supports diverse communities of algae, invertebrates, and fish.
Key Species
🐌
Common Periwinkle
Littorina littorea
A marine snail that grazes on algae. Can survive extended exposure by sealing itself inside its shell with a trapdoor-like operculum.
Adaptations: Operculum seals in moisture; can go dormant for weeks; thick shell resists wave action
Role: Controls algae growth on rocks; important food for crabs and shorebirds
Local importance: Actually an invasive species from Europe, now dominant on Northeast rocky shores
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Acorn Barnacle
Semibalanus balanoides
These crustaceans cement themselves to rocks and filter feed using feathery appendages called cirri when submerged.
Adaptations: Calcium carbonate plates protect soft body; can close plates to retain water at low tide
Role: Creates microhabitat for other species; food for snails and fish
Local importance: Forms distinct white band in high intertidal zone; key zonation indicator
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Forbes Sea Star
Asterias forbesi
A common sea star that preys on mussels and barnacles. Can regenerate lost arms and even grow a new body from a single arm.
Adaptations: Tube feet create suction to pry open shellfish; everts stomach to digest prey externally
Role: Keystone predator that controls mussel populations and maintains biodiversity
Local importance: Common in tide pools at Montauk and North Shore; indicator of ecosystem health
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Blue Mussel
Mytilus edulis
Forms dense beds attached to rocks by strong protein threads called byssal threads. Important filter feeders.
Adaptations: Byssal threads stronger than steel by weight; can filter 1-2 liters of water per hour
Role: Foundation species creating habitat; filters water; food for sea stars, crabs, and birds
Local importance: Both wild harvested and aquacultured in Long Island waters
🔬 Key Ecological Concepts
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Intertidal Zonation: The rocky shore is divided into splash zone (lichens), high intertidal (barnacles, periwinkles), mid intertidal (mussels, seaweeds), and low intertidal (sea stars, sea urchins). Each band represents different tolerances to desiccation and heat.
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Keystone Species: Sea stars are a classic keystone species—their removal causes mussel populations to explode and outcompete other species, reducing biodiversity. This concept was first described studying Pacific rocky shores.
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Tide Pool Ecosystems: Tide pools are isolated miniature ecosystems during low tide, where temperature, salinity, and oxygen can fluctuate dramatically. Species living here must tolerate extreme conditions.
Open Ocean (Pelagic Zone)
The waters off Long Island's coast connect to some of the most productive fishing grounds in the world. The continental shelf extends about 100 miles offshore before dropping into the deep Atlantic. Warm Gulf Stream waters periodically push northward, bringing tropical species, while nutrient-rich cold water upwellings support massive schools of forage fish that attract whales, sharks, and tuna. Montauk is renowned as one of the sport fishing capitals of the world.
Key Species
🦈
Blue Shark
Prionace glauca
The most abundant pelagic shark in Long Island waters. These sleek predators follow the Gulf Stream and prey on squid and fish.
Adaptations: Counter-shaded coloration; large pectoral fins for gliding efficiency; electroreception to detect prey
Role: Apex predator maintaining fish population balance; scavenger removing weak individuals
Local importance: Common catch for Montauk shark fishermen; population has declined due to overfishing
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Humpback Whale
Megaptera novaeangliae
Increasingly common in New York Bight waters, drawn by abundant menhaden. Often spotted from Long Island beaches.
Adaptations: Baleen plates filter small fish; bubble-net feeding behavior; long migrations between feeding and breeding grounds
Role: Whale feces fertilize surface waters with iron; carcasses support deep-sea communities
Local importance: Recovery success story; whale watching has become popular from NYC and Montauk
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Atlantic Bluefin Tuna
Thunnus thynnus
One of the ocean's most powerful predators, capable of speeds over 40 mph. Highly prized in sushi markets.
Adaptations: Warm-blooded (endothermic) for sustained high-speed swimming; retractable fins reduce drag
Role: Apex predator; indicator of ecosystem health and prey availability
Local importance: Montauk is a bluefin hotspot; strict quotas due to past overfishing
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Longfin Squid
Doryteuthis pealeii
A keystone prey species that supports countless predators. Forms massive spawning aggregations in Long Island waters.
Adaptations: Jet propulsion; chromatophores for instant color change; large eyes for low-light vision
Role: Critical link in food web connecting plankton to large predators; highly efficient energy transfer
Local importance: Major commercial fishery; used as bait and for calamari
🔬 Key Ecological Concepts
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The Gulf Stream Effect: This warm current brings tropical species northward along Long Island's coast. Its position shifts seasonally, affecting which species are present. Warm-core eddies that spin off can trap tropical fish far north of their usual range.
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Upwelling: When winds push surface water offshore, cold, nutrient-rich water rises from the deep. This fuels phytoplankton blooms that support the entire food web, making the waters off Montauk exceptionally productive.
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The Forage Fish Connection: Species like menhaden, sand lance, and Atlantic herring are the critical link between plankton and large predators. Their abundance determines whether whales, tuna, and striped bass will be present in an area.
Seagrass Meadows
Eelgrass meadows in the Peconic Bays and other protected waters represent one of Long Island's most valuable yet vulnerable habitats. These underwater meadows provide shelter for juvenile fish, stabilize sediments, improve water clarity, and sequester carbon at rates exceeding terrestrial forests. Historic eelgrass beds were devastated by disease in the 1930s and more recently by declining water quality, but restoration efforts are underway.
Key Species
🌿
Eelgrass
Zostera marina
The only true seagrass native to Long Island waters. Not a seaweed—it's a flowering plant with roots, stems, and leaves.
Adaptations: Underwater pollination; can absorb nutrients through leaves; tolerates brackish conditions
Role: Foundation species providing habitat structure, food, and oxygen; carbon sink
Local importance: Major restoration efforts in Peconic Bays; indicator of water quality
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Bay Scallop
Argopecten irradians
Lives attached to eelgrass blades. Has dozens of blue eyes along its mantle edge and can swim by clapping its shells.
Role: Predator on small invertebrates; indicator of healthy seagrass habitat
Local importance: Rare sightings in Long Island seagrass beds; populations declining
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Green Sea Turtle
Chelonia mydas
Juveniles visit Long Island in summer to graze on eelgrass. One of few marine reptiles that becomes herbivorous as an adult.
Adaptations: Serrated jaw for cutting seagrass; salt glands excrete excess salt; can hold breath for hours
Role: Grazing maintains seagrass health by preventing overgrowth; transports nutrients
Local importance: Endangered species; occasionally strands in fall when waters cool suddenly
🔬 Key Ecological Concepts
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Blue Carbon: Seagrass meadows capture and store carbon dioxide faster than terrestrial forests. Long Island's seagrass restoration is part of climate mitigation strategies, as healthy meadows can sequester carbon in sediments for centuries.
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Water Quality Feedback: Seagrass needs clear water for photosynthesis, but also helps create clear water by trapping sediments and filtering nutrients. This positive feedback means meadows can rapidly expand—or collapse—based on water quality.
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Nursery Habitat: Seagrass meadows provide shelter and food for juvenile stages of commercially important species. An estimated 70% of recreationally caught fish in Long Island depend on seagrass at some life stage.
📝 Marine Environments Quiz
You've explored all 5 environments! Answer 5 questions to unlock Part 2: Waters of Long Island.
You need at least 4 out of 5 correct to proceed.
Score: 0 / 5
Lab Progress
1 of 5 environments explored
🗺️ Waters of Long Island
Long Island is surrounded by a remarkable variety of bodies of water — from the calm, brackish bays of the south shore to the powerful open Atlantic, the tidal Long Island Sound, and the protected harbors between the forks. In this activity, you'll identify 8 key bodies of water and then test your knowledge by matching water characteristics to their locations.
📍 Label the Waters
A marker on the map is highlighted. Select the correct body of water below.
Click "Start" to begin labeling!
🔎 Water ID Challenge
Clue 1 of 8
Complete Phase 1 first, or click "Start Challenge" to begin!
Click on the correct marker on the map above.
🚨 Ecosystem Rescue: Long Island
Environmental threats are hitting Long Island's waters! Read each scenario, choose the best response, and keep the ecosystem healthy. You need to maintain ecosystem health above 0% to save Long Island!
