Patterns in the Marine Environment

Marine ecology - study of interactions between organisms and biotic/abiotic environments and effects of interactions on patterns of distribution and abundance

• Temperature - thermoclines, seasons, latitude
• Light - depth, particulate number
• Salinity - estuarine/rock pool gradients
• Water depth - pressure
• Tides - daily/spring-neap cycles
• Waves - movement and pressure
• Currents - carry particles and cause erosion
• Viscocity - temperature related
• Density - salinity and temperature related
• Substratum
• pH
• Nutrients

• + = Positive
• - = Negative
• 0 = No effect

• Predation (+/-)
• Parasitism (+/-)
• Competition (+/- or -/-)
• Territoriality (+/- or -/-)
• Commensalism - one lives on, in or with another (+/0)
• Mutalisim (+/+)
• Facilitation (+/0 or +/+)
• Succession - change in organisms over time

Studies how organisms survive under varying physico-chemical conditions - how find mates, shelter, food 

Ecological niches - range of environmental parameters over which species lives

Examples -

• Cleaner wrasse picking off parasites from marine fish
• Giant owl limpet as secondary substrate for chitins

How populations of same species distributed and how they persist in current conditions and changing environment

Involve numerical descriptions of populations e.g. abundance, biomass, production, growth rates

Population change over time dependent on species characteristics e.g. life history, growth, survival, immigration/emigration

Limiting resources affect population growth and dispersal potential

Genetic characteristics of species affect ability to adapt to changing environments

Life history - series of changes in organism during its' lifetime e.g. growth, mating, mortality

Example - bloom studies of E. huxleyi off coast of Cornwall

Studies how different populations interact

Distribution and abundance of populations of species determined by combo of:

• Larval/adult dispersal
• Inter-specific competition
• Grazing/predation 
• Parasitism/disease
• Disturbance (physical/biological)
• Facilitation/succession

Examples:

• Sponges and encrusting invertebrates competing for mangrove root space
• Predation by startfish lowering mussel distribution

Studies how whole ecological communities affected by physical environment

Ecosystems influenced by wide range of physical variables:

• Spatial/seasonal abiotic factor patterns
• Geological forces
• Historical factors
• Cyclical/sporadic climate processes
• Anthropogenic impacts

Examples -

• Coral bleaching
• Exposed and sheltered rocky shores
• Overfishing effects

Paleoecology - deals with relations and interactions between ancient life and their environments

Studies ecology over deep time

Look backwards -  inform ourselves about present and future ecology e.g. past climate events

Examine patterns of marine diversity over time - mass extinction events, evolutionary relations and global climate/geological processes

Nature and type of organisms changes over 10s/cm in shallow sea = zonation apparent

Causes of zonation in littoral zone:

• Vertical tidal height gradient
• Horizontal gradient of wave action exposure
• Particle size gradient
• Marine-freshwater salinity gradient

Higher variability in the higher shore as opposed to lower shore - variation in heat and light causes stresses

Exposed shores have more biotic benefits e.g. larval supply, upwelling, oxygen but organisms are under more stresses from exposure

Larger scale - water column has strong patterns of zonation occur across full depth range

Vertical stratification in oceans affects ecological processes:

• Light - euphotic, twilight, midnight
• Temperature - thermocline
• Salinity - halocline
• Oxygen - oxycline
• Nutrients - nitracline

Major surface ocean currents produces horizontal variation in sea surface temperature and depth of mixing

Differences in sea surface temperature (SST) highlighted by Gulf Stream and warm/cold core rings - affect geographical range limits

Variation changing due to climate effects - rising sea, increased CO2 etc

Biogeography - identifies and characterizes geographical distribution of plants and animals, how communites form ecosystems and geographic limits

Under experimental conditions, species tolerate environmental conditions in excess of naturally found conditions

At edge of geographical range, species susceptible to local extinctions

If species distribution has abundant centre = most common in areas in centre of geographical range

Macro-ecology - relationship between organisms and environment at large spatial-scales

Strong positive relationship between local and regional diversity - lower latitudes have higher species richness

Small regions may have high diversity = skewed relationship

Terrestrial environment - predict 'community types' using set of factors

Done in marine environment w/ high-resolution CZCS images of phytoplankton 'greenness' (biomass)

Based on algal growth, environmental forcing agents and fauna at other trophic levels - Longhurst identified 4 primary biomes, based on agents determining mixing layer

• Trades
• Westerlies
• Polar
• Costal

Biomes subdivided into provinces, based on climatology of mixed layer depth, water transpanency and surface nutrients

Biodiversity - diversity among living organisms (+ those ever lived), including diversity within a species, between species and of ecosystems. 3 components:

• Ecological - biomes/provinces, ecosystems, habitats
• Organism - kingdom, phyla, species
• Genetic - populations, individuals, molecular

Species richness common method of quantifying diversity

• Morpho-species - observable structural differences
• Cryptic-species - molecular differences (genetics used to distinguish)

Biodiversity can vary with space, both along latitudinal and longitudinal gradients

• Latitudinal gradients - greatest diversity in equator/sub-tropics region
• Longitudinal gradients - greatest number of species in Indo-West Pacific region - to do with islands creating costal shelf seas with warm waters = faster evolution

Not just about species richness but encompasses morphological richness and measured as disparity (difference)

Species assigned different functional groups based on niche

Positive relationship between functional diversity of ecosystem and number of functional groups

Functional diversity - measure of number of different functionally distinct species in given area e.g. grazers, producers, filter feeders

Keystone species - play a significant role in ecosystem function (if removed = major consequences for ecosystem)