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Ecology of a Rocky Shore Community

Ecology of a Rocky Shore Community. Understanding the Influence of Tides. Tides have a powerful influence on how and when we play at New England beaches. During low tide on Cape Cod Bay, it's often possible to walk 1/2 mile out onto the flats in ankle-deep water.

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Ecology of a Rocky Shore Community

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  1. Ecology of a Rocky Shore Community

  2. Understanding the Influence of Tides • Tides have a powerful influence on how and when we play at New England beaches. • During low tide on Cape Cod Bay, it's often possible to walk 1/2 mile out onto the flats in ankle-deep water. • Six hours later, the water is suddenly too deep to stand in. • Tides cause currents that greatly affect fishing, kayaking, swimming and surfing

  3. Cause and Affects of Tides • The ebb and flow of tides are caused by the gravitational effect of the Sun and Moon on the Earth. • Because the Moon is much closer to Earth than the Sun, its influence is much greater. • When the Moon is up, it pulls water beneath it outwards into a bulge. On the opposite side of the Earth, a similar bulge is also formed by water being moved outward from the planet's rotation. • These two bulges travel around the globe, producing (in most places) two high tides every day.

  4. The water Bulge makes Tides

  5. Wave Action Tides directly affect wave height Waves are a powerful force Tidal currents change direction twice a day and can run at speeds of up to 5 knots around points and at harbor entrances

  6. The Angry Sea

  7. Zones of Life along a Rocky Shore

  8. Rock Intertidal Zones • C is the splash zone: not submerged except in storm tides • D is the high tide zone: covered during high tide • A is the mid tide zone: covered much of every day • B is the low tide zone: covered most of the time, only exposed during high tide.

  9. Why are some animals and plants located in special zones and not all over?

  10. Adaptations for life on a high energy rocky shoreline • High energy waves • Low tide exposure

  11. Animals on a typical New England rocky shore

  12. Asian Shore Crab (Hemigrapsussanguineus) • Periwinkle snails(Littorinalittorea) • Blue Mussels(Mytilusedulis) • Purple Sea Urchin(Strongylocentrotuspurpuratus ) • Rock Barnacles (Chthamalusfragilis) • Common Sea Star(Asteriasforbesi)

  13. Algae on a typical New England rocky shore • Fucus (Fucusgardneri ) • Knotted Wrack (Ascophyllumnodosum) • Kelp (Laminaria)

  14. More Algae Types Ulvalobata (Sea Lettuce) Chondrus (Chondruschrispus)

  15. Adaptations to life on a rocky shore lineAdapting to Wave Shock • Barnacles • Cements shell to rock • Snails • Use a suction cup like foot

  16. Adaptations to Wave Shock • Sea Stars and Urchins • Tube feet with suction cup ends

  17. Adaptations to Wave Shock • Blue Mussels • Byssel Threads ( strong cables)

  18. Adaptations to Wave Shock • Crabs and Lobsters • Wedge into rock spaces • Hide under rocks

  19. Adaptations to Wave Shock • Sea Weeds (macroalgae) • Hold fasts attach to rocks

  20. Rocky shore animal feeding adaptations • Barnacles • Filter food with feathery legs (filter feeder) • Snails • Scrape food with a radula - tongue with teeth (grazers and carnivores) • Sea stars • Use tube feet and stomach

  21. Reproduction adaptations • Barnacles are hermaphrodites • Each barnacle has both male and female reproductive organs

  22. Sea star and Urchin Reproduction • Sea stars and Urchins broad cast eggs and sperm into the water

  23. Marine Snails • Marine snails mate and deposit egg cases

  24. Marine Arthropods like crabs and lobsters mate. • Female attracts male using pheromones. • After the female molts and mates with the male, eggs will later be deposited on underside of her abdomen and carried until they hatch.

  25. Lobster with eggs • Green crab with eggs

  26. Off Shore In the Bay! The Harbor Seal (Phoca vitulina)

  27. Eastern Atlantic Harbor Seals • Live along the western coast of Europe and along the New England shoreline • They like to haul out on flats that are uncovered at low tide. • These seals are also seen in estuaries.(Narragansett Bay!) • They spend about 80 percent of their lives in the water.

  28. Harbor Seals Appearance • Have a fat body and a narrow-pinched head. The nostrils are narrow and show a typical V-shape. The eyes are quite big and close set to each other. • The seals' belly is always lighter than its back. • It is difficult to distinguish males from females. • The seals' back usually shows varied spots.

  29. The Eastern Atlantic Harbor seals' fur color varies from grey to brown. The animals have black spots on their body.

  30. Seal Life-cycle The females reach sexual maturity in 3 of 4 years of age. Males reach sexual maturity at six years of age. These seals eat a variety of fish: squid, sole, whiting, herring, shrimp, and mussels.

  31. Life-Cycle • Unlike most other pinnipeds harbor seals are generally solitary. • They are not highly communicative, but when feel threatened they may respond by lunging, scratching, snorting, growling or other aggressive communications. • Although they are solitary they haul out in small groups for protection from predators. • They haul out on rocky shores, sand beaches, reefs, piers or ice, to breed, moult and rest. • Moult takes place in July and August. During this time the seals' metabolism is reduced. They eat very little so conserve the energy usually expelled finding food.

  32. A Male Display

  33. Haul Out

  34. Pups are weaned after 4 up to 6 weeks. • Due to the high percentage of fat in the mother's milk (45%) the pups double their weight by the time they are weaned. • From birth on the pups immediately can swim and dive. After 2 days the pups can remain submerged for about 2 minutes.

  35. Mating • During the summer time the seals come together to give birth and nurse their young. • Mating takes place right after weaning. • Unlike other mammalians the ovum becomes implanted in the wall of the uterus approximately three months after breeding. • This makes it possible to both nurse pups and breed in the short period the seals are together. • During the mating season male seals can become very aggressive. • They may fight when competing for a female. • The males also display aquatic performances and vocalizations to attract a female.

  36. Threats to the Harbor Seal • Natural predators: killer whales, sharks and polar bears. • They usually remain in the vicinity of their traditional breeding area year round. • Due to this restricted range the viability of harbor seal populations can be at risk. • the population in Lake Ontario disappeared in the early 1980's. • In some areas (Norway, Iceland) people still hunt them • In other countries (e.g. the United Kingdom) fishermen may shoot those that became entangled in fishing nets. • Fishing nets, plastic wrapping bands and marine debris are also threats • Hunting and water pollution has drastically decreased the population of Eastern Atlantic harbor seals in the waters of The Netherlands. • Down to less 500 in 1975, out of aprox 3000 seals. • the population recovered slowly, In 1987 about 1,000 seals • Pollutants decrease the productivity and may cause premature births. • Some seals have been killed by being trapped in the intake pipes of power plants.

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