Rocky shores

Flussdiagrammknoten

• rocky shores extension of the marine environment - interface dynamic environments densely populated and high diversity range of problems 

• tides -caused by gravitational attraction - variation in tidal hieghts - spring and neap - semidirunal tides in the uk - emersion/immersion patterns cause problems for organisms 

• coping 

• behavioural -shelter in crieves, burrows and under boulders - clamps to rocks - close into shells - huddle together - stay in pools 

• physiological produce mucus tolerant to desiccation 

• Morpological- size -shape

• wave exposure wave exposure exerts more influence then anywhere else - destructive mechanical effect - disturbs sediment , circulates water and renews oxygen - extends limits of the intertidal zone - structural damage, moves aniamals 

• coping - fix to substarte -thick shell - live in crevices or under rocks - live sheltered zone - adaptive morphology

• Vertical distribution - not random biota are found in distinct zones at particular hieghts = zonantion they are the same around the world in places with similair conditions 

• zones high shore - littoral zone - small snails, lichens and blue-green algaemid-shore - eulittoral zone - barnacles, limphetrs, mussels and fucoid algae - low shore - sublittoral zone red green algae and kelps 

• causes - Originally assumed related to emersion tolerance - but organisms adapt to number of factors both physical and biological 

• Biological 

• physical 

• desiccation - influenced by tolerance ability - can set upper limits of organisms especially in high shore

• Temperature- sublethal effects on the intertidal organisms - may die from either cooking or freezing ie pelvetia and fucus spiralis

• light - direct exposure to UV waves - unknown if this contols distribution 

• algae - could be a regulator - different algae absorb different wave lengths - diff pigments green - red brown - yellow/ green red - green no experimental evidence that it does this 

• competition - main one is space 

• predation - not only prey but also other 

• grazing herbivore grazing excludes algae

• behaviour movement in relation to tides 

• larval settlement affected by substrate 

• limitations - patterns not always clear - overlapping zones - more then one factor for each zone for each species- visual patterns only picks up main species - can be used to predict genral but not specific patterns 

• tidal height- most are marine in origin - species on upper shore adapted to survive long periods out of the water - lower shore are fully marine almost - correlation between hieght and tolerance - changes for motile and no-motile

• effects on the upper limits of non-motile- upper contorlled by abiotic factors - occasional extremes of temperature - effects of temperature may be subtle - juveniles more vulnerable than adults - biotic factors may also be important in setting upper limits of distribution 

• lower limits most likely controlled by biotic factors - competition between flucoid algae grazing by patella vulgatadrier upper zones inhabitedby more tolerant organisms - can grow anywhere on the shore in optimum conditions most intertidal species will grow offshore - often larger in these favourable conditions 

• effectscommunities comprising zones vary from shore to shore = effects zonantion patterns- sheltered shores covered in dense turf of macroalgae - exposed shores fewer plants and more barnacles - biological exposure scales have been developed 

• sheltered shores - zonation may not be as immediately visible - dense macroalgae - no obvious splash zone - animals abundant under cover - littorina littorea - barnacles are patchy - patella vulgata limited to a few large individuals - Ascophyllum nodosim present

• semi-exposed shore - algae patchy no ascophyllum - fucus in the form with no air bladders barnacles and nucella lapillus widespread - patella widespread-  kelps abundant in sublittoral zone digitata- obvious black littoral fringe due to verrucaria maura 

• very exposed - few brown algae saccharina in sublittoral - fucus absent and replaced by red algae - mostly covered with vulgata, barnacles and nucella lapillus- vesiculosus stunted and in patches 

• extreme exposure - alaria esculenta upto midhsore - crustose coralline algae an open rock to midshore and even upper shore hieghts - vulgata stunted in size and rare ulyssiponensiscommon on open rocks at all heights - lapillus extremely thin shell 

• physical battering on morphology and size attaching species it means risk of destruction increase with size smaller on exposed shores weak clinigin power means easily dislodged = affects distribution - more sheltered shores nucella lapillus - investment in too greater cling of foot = less into anti predator of shell = thinner shell walls 

• salinity open shores - fairly constant - very local change- greatest changes in tide pools and estuaries - dominated by ulva species which have a high tolerance of salinity chnages 

• estuaries - richness decrease as you increase the distant - due to dcreasing or varianle salinity - suspended silt blocking feedind mechanisms or biotic factors - changes in salinity affect sizes and distribution ie spiralis and vesiculoseus replaced by ceranoides 

• effects of temperature 

• low temperature- harsh freezing = frozen cell contents-mollusc are tolerant - as low as -20 -sudden are more deadly then general - freezing of extracellular fluids occurs first and has desiccating effects - intracellure freezing and ice formation damages cell walls 

• high temperatures - high shore especially when uncovered for days - structures that seal them off - gastropod operculum - vulgata - mucus seal gap of shell and subsratum increased problems with desiccation

• plants similiar to animals - can survive at low temps -phtotsythetic recovery depends on temperature and time at certain temperatures - also high shore species are better at withstanding low temperatures 

• grazing - pp - red, green, brown algae - can be substantial but microalgae = main food - diatoms and blue-green algae and macroalgae food for herbivores - size increase = less eaten = enter food chain as ditritus 

• algal-grazer relationship  this is a complex relationship which depends on three main factors which are physical such as wave action, species specific consumers and predator influence. 

• effects of predatiom important structuring communities few but specilised predators so prey is either sessile or motile ,aim = gastropod molluscs - whelk nucella lapillus shore crab moves with tide to crieves and pools fish (gobbies) invade at high tide - birds are low tide predators 

• predators affect vertical distribution depends upon physical = wave action direct effects on density amd distribution effects on density and distribution of prey indirect effect on the balance of competition on the shore 

• recruitment- meroplankton dependent on phytoplankton = relationship with dpring bloom may be crucial for animal larvae losses = huge only few reach maturnity unclear in many cases whether larvea settle passively or not depends on the weather 

• competition inter,intra and aggression important in structuring communties in moderately harsh conditions levels of competition can be affected by recruitment

• high = competition/predation become important in structuring low = competion and predation become unimportant