Biota of Tropical Aquatic Environments

1
Biota of Tropical Aquatic Environments

• An Overview

2
Taxonomic Classification

• Prokaryotes
• - Bacteria
• - Archaea
• Eukaryotes
• - Protista
• - Fungi
• - Plantae
• - Animalia

3
Functional Classification

• Energy Source
• Phototrophs
• Chemotrophs
• Carbon Source
• Autotrophs
• Heterotrophs

4
Ecological Classification
5
Producer Efficiency

• Gross 1o Production (GPP)
• GPP/Solar flux
• 0.5 4.0 efficiency.
• Net 1o Production (NPP)
• GPP - Respiration
• NPP/GPP
• 30 - 80 efficiency.

6
Primary Consumer Efficiency
50 cal
Heat
10 cal Growth/ Reproduction
100 cal
40 cal Waste
100 cal
Not Eaten
200 cal
7
Classification According to Life Form
8
Plankton

• Small organisms suspended in the water column,
  with no or limited powers of locomotion. Plankton
  ranges in size from lt 2 µm (picoplankton), 2-20
  µm (ultraplankton), to gt20 µm (microplankton).
• Phytoplankton refers to small plant plankton.
• Zooplankton refers to small animal plankton.

9
Periphyton

• Community of microscopic organisms (bacteria,
  algae, protozoa, small metazoa) growing attached
  to substrates (rock, plant, animal, sand)

10
Benthic Invertebrates

• Non-planktonic animals associated with substrate
  at the sediment-water.
• Epibenthos live and move about on the lake
  bottom.
• Infauna are organisms that burrow beneath the mud
  surface.

11
Nekton

• Actively swimming organisms

12
Neuston (Pleuston)

• Organisms (plant or animal) resting or swimming
  on the surface.

13
Prokaryotes

• Archaebacteria (archaea)
• Eubacteria (bacteria)
• Density
• 1,000,000,000 / g sediment (less in water)
• Diversity ca. 5,000 species known (millions may
  exist)
• Surface area volume ratio high

14
(No Transcript)
15
Surface Area to Volume Ratios
r 1 µm
Surface area (s) 4(pi)r2
s 12.6 µm2
3.0
V 4.2 µm3
Volume (V) 4/3(pi)r3
r 20µm
s 5028 µm2
0.15
V 33520 µm3
16
Protozoa (1-2 days)
Rotifera (3-5 days)
Cladocera (7-14 days)
Copepoda (3-5 weeks)
17
Numbers, biomass and productivity of
bacterio- plankton generally increase with
increasing trophic state and temperature.
Tropical aquatic systems

• High bacterial density ( 109/L vs. 108/L in
  temperate systems)
• High bacterial activity
• Rapid decomposition and re-use of inorganic
  compounds (4-9 x faster than in the temperate
  zone)

18
Bacteria

• Autotrophs (examples)
• Purple sulfur bacteria (anaerobicCO2 H2S
  ? CH2O S)
• Green sulfur bacteria (anaerobic ditto
  but different light wavelength)
• Cyanobacteria (blue-green algae)
• Heterotrophs. Decomposition of particulate and
  dissolved organic matter.
• Rates of decomposition determined by
  chemical composition of organic matter, pH,
  temperature, availability of electron acceptors.
• Parasitic. Significant role in the spread of
  water-borne diseases (cholera, dysentery,
  salmonella, etc.)

19

20
Bacteria

• Autotrophs
• Purple sulfur bacteria (anaerobicCO2 H2S
  ? CH2O S)
• Green sulfur bacteria (anaerobic ditto
  but different light wavelength)
• Cyanobacteria (blue-green algae)
• Heterotrophs. Decomposition of particulate and
  dissolved organic matter.
• Rates of decomposition determined by
  chemical composition of organic matter, pH,
  temperature, availability of electron acceptors.
• Parasitic. Significant role in the spread of
  water-borne diseases (cholera, dysentery,
  salmonella, etc.)

21
Role of Heterotrophic Bacteria in Food Webs
Bacterial Decomposition
22
algae
bacteria
23
Protozoa may also consume cyanobacteria
Cyano bacteria
Consequences
(1) Toxins may become concentrated in aquatic
invertebrates and passed up the food chain
(2) Additional steps in the food chain decrease
food transfer efficiency to higher trophic levels
24
Bacteria

• Autotrophs
• Purple sulfur bacteria (anaerobicCO2 H2S
  ? CH2O S)
• Green sulfur bacteria (anaerobic ditto
  but different light wavelength)
• Cyanobacteria (blue-green algae)
• Heterotrophs. Decomposition of particulate and
  dissolved organic matter.
• Rates of decomposition determined by
  chemical composition of organic matter, pH,
  temperature, availability of electron acceptors.
• Heterotroph Parasitic. Significant role in the
  spread of water-borne diseases (cholera,
  dysentery, salmonella, etc.)

25
Tropics and the Transmission ofInfectious
Diseases

• Cultural factors
• Lower standards of hygiene and health care
• Lower standard of living (e.g., refrigeration,
  water supply wastewater treatment)
• Higher incidence of nutritional deficiencies
  (lower resistance)
• Active control of vectors in non-tropical regions
  (spraying, draining of wetlands, etc.)
• Ecological factors
• High temperatures, high humidity Disease vectors
  (e.g., mosquitos, flies) are more abundant
  (particularly during the wet season)
• Increased exposure to contaminated water and soil
  (particularly during the wet season)
• Vectors survive year round

Source Sattenspiel 2000
26
Bacterial Waterborne Diseases

• Clinical Features
• Acute dehydrating diarrhea (cholera), prolonged
  febrile illness with abdominal symptoms and
  malaise (typhoid fever), acute bloody diarrhea
  (dysentery), etc.
• Common agents
• Vibrio cholerae, Campylobacter spp., Salmonella
  typhi, Shigella spp., and the diarrheogenic
  Escherichia coli.
• Incidence
• Each year, an estimated 3 million deaths (mostly
  among children) result from diarrhea. Waterborne
  bacterial infections may account for as many as
  half of these deaths.

More information Centers for Disease Control,
World Health Organization
27
Bacterial Waterborne Diseases

• Sequelae
• Many deaths among infants and young children are
  due to dehydration, malnutrition, or other
  complications.
• Transmission
• Contaminated surface water and poorly-functioning
  water distribution systems contribute to
  transmission of waterborne bacterial diseases.
  Chlorination, safe water handling, and water
  treatment can reduce the risks of transmission.
• Trends
• Improvements in water and sanitation
  infrastructure have barely kept pace with
  population increases and migrations in the
  developing world.

More information Centers for Disease Control,
World Health Organization
28
Source http//www.who.int
29
Cholera number of cases and number of countries
reporting
30
Cases of cholera reported to WHO by continent and
by year, 1990-2000