Supply-side Ecology

Nota:

• whay study supply side ecology
• to understand population fluctuations  changes to adult population interactions  developing marine protected areas  fisherie stock assessments  better understanding of how humans will effect the population 

1. Lewin 1986

   Nota:

   • argued that supply side ecology effects the population size - however this is not a new concept 
2. the dynamics of a population are highly effected by recruitment = defined as when new individuals enter the population
   1. Production of larvae

      Nota:

      • this is effected by the number  and distribution  of breeding adults  Fecundity - number of viable eggs  sperm dilution and successful fertilisation 
   2. Dispersal

      Nota:

      • most adults are benthic and habitat the shore but have pelagic larvea which go of shore the grow 
      • this means that they need a way to get back to the shore to be recruited into the actual population 
      1. duration of the planktonic stage
         1. pechenik 1999

            Nota:

            • 55-85% produced long lived planktotrophic larvae,  5% produced short lived larvae  10% produced Lecithtrophic larvae
         2. short lived larvae mostly like to be retain in local popopulation
         3. the longer the planktonic period the higher dispersal distant
         4. however long lived plankton can be kept local by oceanic features or larval behaviour
      2. Transport processes
         1. Oceanic processes

            Nota:

            • Large scale currents  mesoscale eddies  fronts  upwelling  wind driven currents  internal waves / bores 
            1. sotka et al 2004 , roughgarden 1988

               Nota:

               • oregon vs california  due to ekman transport 
         2. larvae behaviour
            1. Passive or not?

               Nota:

               • it has long been thought that plankton are passive swimmers and let the current take them, traveling at <1 mm sec-1. 
               • the diffferece between the position of crustaceans and brozoa larvae disproves this - j. Pineda 
            2. Tankersley 1988

               Nota:

               • noted that females used ebbi-currents to travel seawar to spawn and flood-tide to re-enter the estuary the larvae remain near the surface for the whole of thier development 
            3. Olmi 1994

               Nota:

               • ebb flow means that larvae should be pushed to the bottom and flood should cause and increase in the water column 
               • this was shown to be true but instead of the travel time being 6.5 days it was inly 3 so behaviour must cut this down 
      3. larvae mortality
         1. morgan 1995

            Nota:

            • predation  food resources  physiological stress  sinking and avection 
         2. mismatch hypothesis

            Nota:

            • phenology is the life cycle events in an oragnims life, this are normally set to environmental cues. 
            • prey and predator life cycles normally peak within the same time as to keep the predator levels high 
            • however a time lag can occur to due changges in the environment, meaning there are lower number of prey to feed on = different levels of starvation and survival for the predators 
            • this means less will survive to become adults effecting the population numbers and survival ratings. 
            • this misatch is mostly caused by an increase in temprature such caused by global warming. 
         3. food supply and survival

            Nota:

            • planktotrophic species relie on food to survive in the water column  there are two main stragies to overcome this 
            1. synchronised spawning

               Nota:

               • this is where enviromnetal cues and levels of prey induce spawning
               • seen in the northern boreal species  there larvea are released in links with storm events or when thier is a high phytoplankton bloom,  mismatch in bloom can lead to lower recruite ment 
            2. physical adapatations and tolerance

               Nota:

               • some plankton have developed a adaptations for low food levels to prevent stravation many of these are frequent spawners 
               • Elminius modestus  these are frequent spawners, producing many yearly broods no environemntal cue is needed for this to occur 
   3. Settlement

      Nota:

      • s= N/Ta  n = number of individuals  t= time  a= area 
      • dispersal is a key factor that effects settlement 
      1. choosing

         Nota:

         • those animals that do choose where to settle have a presettle pahse where they test the area such as semibalanus baliniods 
         • a switch from positive to negative phototaxis 
         • water-bourne cues  - conspecifics  - food species - good habitat indicator species 
         • colour and texture cues 
         • exploratory phases - such as semibalanus - where they dont fully attach. 
         • passive interception is where they dont actually chose where they stay just that they attach to the first bit of land that they find, basically the first that they intercept - examples needed 
      2. negative factors
         1. preemtive competition for space
         2. Natural anti-fouling coumpounds
         3. chemical cue of predators
         4. physical disturbance

            Nota:

            • wave  whiplach from algae fronds  bulldozing ie limphets 
   4. metamophisis

      Nota:

      • this indicates the time between presettlement and actual settlement, for different animals this can be from 24 hours to 3 to 4 days this has effects on sampling 
      1. effects on sampling

         Nota:

         • there is a a gretaer chance of being dislogdes and resuspended after being counted 
         • this leads to an overestimation of actual settlement rates which can lead to a difference in biodiversity counts and the strength of a population 
3. is the production of larvea or presettle adults more of a control for settlement
   1. read jenkins 2005 - chthalmus species study
4. how does it effected and interact post setllement
   1. is predetation a controling factor

      Nota:

      • Fairwether 1987  basically if there are laods of prey the predators might get swamp and different compepting species will do better then prefered prey 
   2. is competition a controling factor

      Nota:

      • high variation in the adult population due to competition can lead to a lower settlement 
      • see Gains and Roughgarden 1985  balanus gladula 
      1. type and intensity

         Nota:

         • Intra-specific  juveniles will be present but with smaller bodies  adults maybe effected and suffer fatality  lower food resources can lead to stunted growth and lowered fecundity 
         • interspecific  high larval supply of dominanent species will lead to a competitive exclusive population  low larval supply can lead to co-existence
   3. is there a actual link between settlement and population size