Rocky Shores Flashcards
Which phyla contain meiofauna?
Arthropods (ostracodes & amphipods), Mollusca (gastropods), Foraminifera (Forams).
What are the three types of seaweed?
Chlorophyta (greens, 7000spp), Rhodophyta (reds), Phaeophyta (browns, fucoids and kelps).
What are the main primary producers?
Seaweeds, microalgae.
What are the two types of microalgae primary producers?
Diatoms and Cyanobacteria.
What are examples of grazers?
Limpets, periwinkles, top shells, urchins.
What are examples of filter feeders?
Barnacles, sponges, sea squirts, mussels.
What are some examples of predators?
Shore crabs, dogwhelks, seastars, oyster catchers.
What is the littoral zone?
The near shore area where sunlight penetrates all the way to sediment.
What are the three parts of the littoral zone?
High intertidal, mid intertidal, low intertidal.
What organisms are found in the high intertidal?
Lichens, periwinkles, barnacles, isopods, etc.
What organisms are found on the mid-intertidal?
Barnacles, limpets, mussels, fucoids, whelks, green macroalgae.
What are the organisms found on the low intertidal?
Seastars, kelps, red and green macroalgae, urchins.
What causes patterns of vertical zonation?
1) Larval settlement & adult preference.
2) Physiological tolerance to environmental variables.
3) Biological interactions: interspecific competition/predation.
How do animals tolerate emersion?
They move into crevices, inhabit rock pools, and adapt their body size for volume rations, limiting water loss, or living in dense groups/under seaweed canopies.
What are meiofauna?
Fauna that are
What are the environment variables on the rocky shore? Where do they increase?
Physical, chemical, biological (plant/animal) variables, + unpredictability. They increase the further away from the low shore you get.
What are physical environmental variables?
Emersion factors: greater light/heat & lower humidity cause dessication in tropical & warm regions & cold/freezing in cold, temperate and polar regions.
What are chemical environment variables?
Osmotic problems: greater variation in surface salinity but particularly in rock pools due to rainfall, runoff (lowering) and evaporation (raising.) In pools, variations in O2, CO2 & pH.
What are biological plant environmental variables?
Photosynthesis: less time for uptake of CO2 and H2O, + poor function of photosynthetic tissue out of water. Less time for nutrient uptake (N, P, Si) for protein synthesis, etc.
What are biological animal environmental variables?
Respiration and feeding: less time for O2 uptake, suspension feeding, tide-in foraging by swimming, crawling or walking more difficult in air?
What is unpredictability in environmental variables?
Fluctuation in all factors, preventing acclimation.
What is the sea in terms of environmental variables?
Highly stable: high and constant salinity, little temperature & pH change, plentiful raw materials for photosynthesis, nutrients, food for suspension feeders, supportive medium for swimming/crawling.
What is the shore in terms of environmental variables?
Highly variable: variation in heat and light leading to extremes of hot and cold, winds interact with sunlight to create low relative humidity and hence desiccation stress, variable salinity due to rainfall & evaporation.
What percentage of benthic invertebrates have planktonic larvae?
Around 70%.
What are the advantages of direct developers?
+Predictable food source
+No water column predators.
+Suitable habitat ready when hatched.
What are the disadvantages of direct developers?
+Large reproductive cost for mothers - egg cost & protection.
+Few eggs.
+Poor dispersal.
+Benthic predators.
What are the advantages of lecithotrophic larvae?
+Own food supply.
+Less time for predation.
+Close to suitable habitat.
What are the disadvantages of lecithotrophic larvae (e.g. limpets)?
+Fewer larvae produced.
+Lower dispersal distances (compared to planktotrophics).
What are the advantages of planktotrophic larvae (e.g. barnacles)?
+Large numbers produced (scattergun approach).
+Capable of long periods in water column (up to 6mon)
+Increased dispersal distance from parents.
What are the disadvantages of planktotrophic larvae?
+Unpredictable food source.
+Long exposure to predators.
+Last development stage must be timed when suitable habitat found - high probability of missing the mark.
Why have many marine fauna evolved pelagic larval phases?
+Different food sources to adults: reduces competition.
+Potentially large dispersal range - facilitating colonisation of new regions + increasing gene flow.
+Possibility of breaking parasite cycles.
+No benthic predators.
Where is competition important? What makes a good competitor?
Where resources are limiting, and large size and rapid growth.
What are the three types of competition?
Exploitative, pre-emptive and interference.
What is exploitative competition?
The ability to harvest limiting food resources.
What is preemptive competition?
Competitor recruits to and dominates space.
What is interference competition?
Competitors physically contest resources.
What determines rocky shore communities (7pt)?
\+Recruitment success. \+Resources - space and food. \+Growth rates and body size/shape. \+Competitive ability. \+Biodiversity. \+Predatory effects. \+Disturbance - physical & biological.
What are the causes of species range limits? (5pt)
Life history, population genetics, abundance distribution, spatial availability of habitat, oceanographic/atmospheric factors (or a combination.)
What is phylogeography?
The study of historical processes influencing the modern distribution of organisms (biogeography) using molecular tools.
How do humans create artificial rocky shore substrates?
By the building of seawalls, jetties, groynes, piers, riprap. The biodiversity is similar to natural substrates.
