AIM 2 - Biological Survey

Bacteria

• -          Autotrophic & heterotrophic marine bacteria
• -          < 2 um, Microscopic, unicellular
• -          Removed from water by 0.45 μm/0.2 μm

Plankton

-          Phytoplankton

o   Abundant, widely distributed

o   Microscopic floating plant, < 100 m from surface

o   2 – 200 μm

o   Plankton net tow 60 μm (count & biomass determination)

-          Collecting phytoplankton

o   Standard conical net = fine mesh & 1m ø mouth

o   Towed behind ship at set distance

o   Number of organisms present / species diversity = organism count & filtered volume of water

o   Primary productivity determination = chlorophyll-a determination

-          Zooplankton

o   Small herbivorous / carnivorous animals

o   Feed on phytoplankton / zooplankton

o   20 – 5000 μm

o   Bongo net of 333 μm / 500 μm (estimate count, sp. diversity, biomass determination)

o   Limited to upper sunlit zone, but deeper

-          Benthos

o   Trawling technique: beam trawl (burrows)

o   Infaunal (sometimes sedimentary) & epifaunal benthos, size distribution, sampling

o   All depth sediment has epi- & infaunal of different density

o   Size division:

§  Megafaunal >20cm

§  Macrofaunal 20cm – 0.5mm

§  Meiofaunal 0.5mm – 50μm

§  Microfaunal 50μm – 0.5μm

Diversity & Stability

• -          Community diversity = species number @ a time (mathematically documented)
• -          High density à High species; few individuals/species
• -          Diversity indices (quantifies community diversity all environment)

o   Simpson index

     

o   Shannon function 

N = total individuals of all species     

ni = number of individuals in ith species

*Common logarithm bases are 1, 10, & e

• -          Community stability depends on time & less defined. If diversity, sp. composition changed little, then community is stable.
• -          Diversity Index esp. used in transects to examine impact of pollutants (land pollution on coastal water & oily water from oil field)

Coral reef

• -          Occupies 1% of oceans
• -          Shallow warm subtropical & tropical water, >3000 species
• -          From coral skeleton, <20m
• -          Zooxanthellae, symbiotics photosynthetic algae (dinoflagellates) live in endoderm cells of coral

Great Barrier Reef

• -          Stretches 2600km, area 344,400km², > 2900 individual reefs
• -          Off Queensland coast

Nekton

• -          Highest-trophic-level organisms in estuaries/oceans sustains locomotion for prey
• -          Fish, crustaceans, cephalopods, seabirds, marine reptiles & mammals