Exploring the Fascinating Intertidal Rocky Shores Ecosystem

INTERTIDAL ZONE

LITTORAL ZONES Characterized by highly dynamic, well marked zonation of organism s, maximum stress on life Tides are the periodic rise and fall of sea level over time Supralittoral Beach zone to the edge of the sea. Sublittoral continental shelf Intertidal Between High tide and low tide mark Spring tides - Neap tides (Twice each day) Diurnel tides Semidiurnal tides (One tide each day)

Types of Intertidal habitat Sandy shore Muddy shore Rocky shore

INTERTIDAL ROCKY SHORE Rocky shores are areas of bedrock exposed between the extreme high and extreme low tide levels on the seashore Vertical Distribution Pattern for Animals and Algae

ECOSYSTEM The ecosystem is complex, as it has interaction between terrestrial and aquatic systems Energy supply - primary production by seaweeds and phytoplankton; organic detritus derived from adjacent land and other intertidal habitats The problem prevailed are evaporation, waves, gradients of temperature and salinity

Living community - hardy plants and animals, specially adapted for coping with the harsh environment Rocky area support a preponderance of epifaune rich and diverse communities of marine plants and invertebrates as well as birds and fishes.

PHYSICAL CHARACTERISTICS Bedrock: resistant bedrock, such as granite, slate and quartzite, erodes slowly and produces steep gradients Wave action: exposure to wave action, related to dominant wind direction, storms, controls plant and animal attachment. Tidal regime: tide range determines the area of shore exposed to the air. Climatic conditions: weather conditions include summer and winter temperature extremes, humidity, precipitation and wind exposure.

Environmental problems Animals encounter wide fluctuations in temperature and salinity Rainfall and land run off lower the salinity Animals exposed to heavy wave action and current motion Desiccation during low tide

ZONATIONS OF ROCKY SHORES Feature - Vertical zonation according to geographical location, tidal range, exposure to wave action/protected etc Zonation is largely based on sessile species such as lichens, algae, barnacle s, mussels etc. Vertical zonation of rocky shore

Vertical zonation of rocky shore Super littoral Zones Encrusting black lichens (algae and fungi) (Black Zone) and blue green algae. Certain species, littorina periwinkles and Large isopods (Ligia) and primitive insects (Machilis) Below the super littoral Periwinkles Littorina sp- dense 10,000/m2, Barnacle Zone white Zone, Mussel Zone Green Zone Attached algae & sessile animals

Adaptation is an alteration or adjustment in structure or habits, often hereditary, by which a species or individual improves its condition in relationship to its environment Common limpets Green Sea Anemone

FOOD WEB ROCKY SHORE There are so many connections between food chains that we can think of every organism (plant or animal) as part of a complicated FOOD WEB rather than as a link in a straight chain

ADAPTATION OF ROCKY SHORE ORGANISMS Bivalve molluscs and barnacles over come desiccation by closing their shells tightly snails retreat into their shells and sealing the shell aperture. Marine algae have strong attachment to rocks by special hold fast. Barnacles, oysters, tunicate cementing on to the substratum Mussels attached by byssal threads Limpets, chitons have suction like attachment Sea urchins and clams boring into the hard surfaces Crabs, isopods live in rock crevices

Productivity of intertidal rocky area is about 100g C/m2/Y average annual productivity May go upto 1000g C/m2 /yr in some favorable area Limpets, chitin, Sea urchin, littorie - grazers herbivores Mussels, barnacles clams tunicates politic filter feeders Starfish, snails, birds, - Scavengers predators isopods, crabs etc.

INTERTIDAL SANDY SHORE Sandy beaches - exposed to sever wave action; makes the transition from land to sea Support high proportion of in faunal species Beaches serve as buffer zones or shock absorbers that protect the coastline, sea cliffs or dunes from direct wave action It is an extremely dynamic environment where sand, water and air are always in motion

FORMATION Formed through the deposition of sand resulting from the erosion of glacial till and bedrock in the area of occurrence Sandy beaches are soft shores that are formed by deposition of particles that have been carried by water currents from other areas The two main types of beach material are quartz (=silica) sands of terrestrial origin and carbonate sands of marine origin The carbonate sand is weathered from mollusk shells and skeletons of other animals Other material includes heavy minerals, basalt (=volcanic origin) and feldspar.

PHYSICAL CHARECTERSTICS Substrate: includes particle sizes ranging from fine gravel to sandy mud Wave action: exposure to wave action, related to dominant wind direction, storm and ocean-swell conditions, and influence of tidal and alongshore currents affects the mobility of the sand Tidal regime: tidal range determines the area of shore that is exposed to the air Water land interaction: water conditions include summer and winter temperature extremes, turbidity and salinity Climatic conditions: air conditions include summer and winter temperature extremes, humidity, precipitation and wind.

ECOSYSTEM PROPERTIES There is no significant primary production, except by blue-green algae and diatoms that occur on the surface of sandy mud in sheltered conditions Energy input -from the phytoplankton and from particulate organic matter (detritus) derived from the land and adjacent intertidal habitats Herbivorous and detritus feeding and carnivorous animals are included in the sand infauna

Environmental characteristics Sand grains are quartz particles mixed with shell fragments Sand particle size varies from < 0.1 to 2 mm. Sandy beaches typically have a gradual slope means, sediments drains and dries slowly Oxygen decreases with depth of soil Anaerobic conditions are due to sulphide layers. Substrate is unstable due to tidal water

Continual shifting of the surface layer Sand contain relatively low organic matter Organisms burrow into sand dig low tide No large attached plants The dominant printing producers diatoms, dinoflgellates and blue green algae Primary productivity is very low <15g Cm2/yr

BIOLOGICAL DIVERSITY Plants Due to the mobility of the substrate, plant life is very limited in both diversity and abundance Seaweeds are mostly absent, but diatoms and bluegreen algae may be common in sheltered, sandy, mud conditions Ulva and Enteromorpha develop in summer on many sandy-mud flats.

Animals On exposed beaches, polychaete worms (Nephtys) and molluscs (Tellina, Spisula, Ensis) occur at low-tide level Isopod and amphipod crustaceans also occur at the mid- and low-tide levels At the high-tide mark, amphipods are common, feeding on organic matter in the drift line, and overlap in their occurrence with insects, including the larvae of flies and beetles Ribbon worms (Cerebratulus spp.), polychaetes (Nereis spp. and Nephtys spp.), bivalves (Mya arenaria, Macoma balthica) and mud snails (Nassarius,) are typical

Macrofauna Macrofauna- exceptionally high densities Molluscs, crustaceans and polychaetes are the most important. Low diversity compared to rocky shore. Polycheates, bivalves and crustaceans are dominant forms Amphipods and isopods burrow during day and feed at night on detritus Ghost crab (Ocypoda) dominant scavenger in sandy beats High species diversity of macro fame at mid and lower tidal zones. Fast burrowing Donax Tellina clams present in large numbers

Larger razon clams (Ensis, Siliqua) are common Cockles (Cardium) Arca sp. thick shelled bivalves also common in sandy Snails Olivella, Natica, Polinices predator and abundant in sandy shores Sand dwelling polychaetes (Napthys, Glycera) are predators /scavengers are deposit feeder at Mid / Low tide level Crustaceans - Mole crab (Emerita) present at mid tidal level Prawns (Crangon) Sandy shore crustacean Echimodesms Heart urchins, sand dollers star fish sea cucumber deposit feeds present at lower tidal levels. Sand eels, flatfish are also burrow into good.

Meiofauna The dominant - nematodes and harpacticoid copepod with other important groups including turbellarians, oligochaetes, gastrotrichs, ostracods and tardigdades Meiofauna interstitial fauna present both sand grass Biomass of meiofauna varied between 10 and 2g/m2 Average numbers to be 106/m2

INTERTIDAL MUDDY SHORE Muddy shore habitats are areas of mud and sandy mud exposed between the extreme-high-tide and extreme low-tide marks. FORMATION Mud flats form from the deposition of mud in sheltered tidal water, particularly in estuaries where there is a large sediment supply

PHYSICAL CHARECERSICS Substrate: particles range from fine sand to silt, and are often compacted into clay. drainage is poor, and anaerobic conditions exist just below the sediment surface. Wave action: the surface sediment is mobile in moderate waves due to exposure to wave action related to wind and to a tidal and longshore currents. Tidal regime: tidal range determines the area of shore that is exposed to the air. Water land interaction: water conditions include summer and winter temperature extremes, formation and movement of ice, turbidity and salinity. Climatic conditions: air conditions include summer and winter temperature extremes, humidity, precipitation and wind.

SPECIAL FEATURES Vast numbers of a few species of infauna depend on a diet of organic detritus Ex: Corophium sp with a population density of 15 000/m2 and Macoma balthica 3500/m2 Support large groups of migrating shore birds during the late summer Migratory fish also visit to feed on the benthic (e.g., Corophium) and epibenthic species (e.g., Neomysis, Mysis etc.).

ECOSYSTEM PROPERTIES Primary production is limited to diatoms and other microscopic and filamentous algae and grass Most energy enters the system from the plankton, or as organic detritus derived from the land or adjacent tidal marshes The detritus --------->bivalve molluscs, amphipods and polychaete----------> carnivores, migratory shore birds The crustacean, Corophium volutator occurs in the Bay of Fundy intertidal mud flats and is an important food source for the migratory Semipalmated Sandpiper.

BIOLOGCAL DIVERSITY Plants Limited to microscopic algae (diatoms) and filamentous algae on the sediment surface, and occasionally seaweeds, such as Fucus spp. attached to stones Some Cord Grass is found at the first stage of tidal-marsh succession, and eel grass occurs on the lower shore

Successional sequence In sheltered areas, the deposition of sediment on the shore will eventually raise the level so that seeded or ice-transported cord grass may become established. The cord grass expands from the point of colonization by vegetative means and accelerates the rate of sediment deposition, developing into the low marsh. When the substrate of the marsh rises to the mean-high-water mark through the accumulation of sediment, the cord grass gives way to marsh hay and associated plants, and the high marsh develops. With further sediment deposition, the vegetation becomes mainly freshwater: cattail, rushes and reeds, possibly in association with spruce (swamp).

ANIMALS Animals - detritus-feeding infauna that can tolerate exposure at low tide. Polychaete worms (Spiophanes wigleyi, Clymenella torquata), amphipods (Corophium volutator) and bivalves (Mya arenaria, Macoma balthica) are common Scavengers and carnivores polychaetes (Neanthes virens), crustaceans (Chiridotea caeca, Crangon septemspinosus) and molluscs (Ilyanassa obsoletus, Lunatia heros) Sessile epifauna species, such as barnacles and slipper limpets, occur attached to small stones lying on the mud surface Mud flats are also important feeding areas for migratory shore birds, such as the Semipalmated sandpiper, and land mammals (particularly raccoons)