EVSC20004 Lecture Notes - Lecture 10: Oceanic Basin, Decapoda, Biogeography
18 May 2018
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LECTURE 10: OPEN COASTS – BIOGEOGRAPHY
Biogeography: the study of where organisms exist and why
• Biogeographic province: define regions with similar sets of species - correlate different regions
o Coastal region: characterised by a relatively distinct and homogenous flora and fauna, with only a
small percentage of species common to adjacent regions
• Qualitative studies - often based on specific taxa/habitats
o Marine bioregions: gov't report, 24 provinces and transitional bioregions
• Why do gov'ts get involved: to provide frameworks for management
• O'Hara & Poore (2000): Echinoderms and Decapods in southern coast of Australia
o Patterns in species composition, species richness and endemism
o Shows species composition is majorly structured geographically
o Some individual species give detailed information about biogeography - find divide between east
and west coast
Factors which Drive Patterns of Biodiversity
External
Organism
Historical
Geological events
Evolution
Dispersal
Ocean currents
Species traits
Habitat
Habitat availability
Species traits
• Historical: breakup of Gondwana = 90Ma, by 30ma Australia separated from Antarctica
o Diff flora/fauna develop on E/W coast during isolation - separate evolution
• Dispersal:
o Large southern coastline of Aus - accounts for rich and abundant flora/fauna
o Unusual to have warm current flowing poleward on east side of ocean basin in southern
hemisphere
o Ability of species to disperse: many benthic species have planktonic stage in life history, giving
them the potential for currents to aid dispersal
• Larvae:
▪ Lecithotrophic larvae: Non-feeding, rely on energy reserves, relatively large and few in
number, short time in plankton (less time dispersing) (mins to hrs)
▪ Planktontrophic larvae: Obtain own food, relatively small & numerous, longer time in
plankton
o More time in water - more potential for dispersal
o Larval Settlement: when to stop dispersing affected by: chemical, light intensity, surface texture,
presence of biofilm
• Habitat suitability
o Temperature: gradient from tropic to poles, varies spatially over smaller scales, has fluctuated
through geological time - SST
o Microhabitat: coastline Aus 36,000km, 50% sandy beaches, 40% rocky shores
