INTERTIDAL ADAPTATION: Vertical Zonation Highest zones:a) black lichen on myxophycean zone b) periwinkle zone (gastropods) c) barnacle-dominated zone d) zone dominated by different spp. (i.e. mussels in N. America) Zone correlates with tidal levels (i.e. upper limit of seaweed) Laminaria - extreme low water in sheltered areas
Wave splash can extend zones Maintenance of zone: 1) selective larval settlement 2) behavioral patterns 3) physical tolerance of org. 4) wave action and tidal range 5) intra- and interspecies competition 6) predation and algal grazing that’s tidal range dependent
Territoriality: many limpets remain at one spot at time of low tide and graze on algae at high in this vicinity Scars develop on substrate Pacific Owl Limpet - Lottia gigatea - defends region
Most animals show positive photoaxis -Macoma balthica -Littorina littorea after a few hours, then negative Littorina eye permits orientation to polarized light
Temperature Stress and Desiccation: Seaweeds and mussel beds retain moisture and harbor invertebrates In winter Ilyanassa obsoleta moves to subtidal regions to avoid danger of freezing Different fauna live on light and dark surfaces (volcanic vs. sandstones and limestones)
Water Loss: Barnacles, mussels, limpets - can seal off loss more effectively than soft-bodied animals - polychaetes, anemones, ascidians Ulva - can dominate mud flats in Flax Pond, N.Y. in winter but die off in summer Ascophyllum nodosum, Fucus vesiculosus very tolerant - when >5% water loss photosynthesis is affected
Dissolved Oxygen and Gas Exchange: Mytilus calif. - ga??? under moist conditions Guekenzia demissus - takes air in at low tide Anaerobic metabolism when oxygen reserve is depleted Also respiratory pigments - Hemoglobin, hemocyanin, chlorocruorin - many polychaetes have these compounds.
Reduced feeding times - time spent feeding reduced in upper zone; these animals tend to be smaller Wave action - Spisula solidissima Emerita Donax denticulatis Ensis
Competition: Acorn barnacle Cthamatus stellatus and Balanus balanoides (better competition in lower zone) Barnacle vs. barnacle (Connell, 1961) Transplanted rocks with newly settled C. stell. to all levels in the intertidal Some rocks were caged to avoid predation by Thais lapillus C. stell. - survivorship was greater in upper but not so in lower (fig. 16-1)
Algae vs. algae Chondrus crispus - lower - resistant to grazing Gastropods - dessication restricts upper F. vesiculosus restricted by gastropods in lower Mussel vs. Algae Caging Exp. (Lubchenco, 1980) In headlands wave exposed coasts removal of Asterias forbesi and vulgaris and T. lapillus results in Mytilus domination. Lubchenco and Menge, 1978
Mussel vs. mussel (Hager, 1968, 1970, 1972) M. edulis vs. M. calif. M. eculis - more mobile, active, in bays M calif. - thick shell, on wave-exposed coast
Mussel - Barnacle Paine, Mukkan Bay (outer Wash. Coast) removed individuals of Pisaster ochraceus capable of devastating both mussel and barnacle following removal % of space occupied by barnacle next year in fall by summer, Mytilus competition dominant and Mitella spp.
Similarly in New Zealand - Stichaster australis were removed for 9 months, which resulted in the extension of the mussel Perna canaliculus (Paine, 1971) Fugitive spp. (Hutchinson, 1957) - spp. adapted to colonizing newly opened ecological space Palm seaweed Postelsia palmaeformis occupy space of Mytilus