Biota of Tropical Aquatic Biota of Tropical Aquatic EnvironmentsEnvironments

An OverviewAn Overview

Taxonomic ClassificationTaxonomic Classification

• ProkaryotesProkaryotes- Bacteria- Bacteria- Archaea- Archaea

• EukaryotesEukaryotes- Protista- Protista- Fungi- Fungi- Plantae- Plantae- Animalia- Animalia

Functional ClassificationFunctional Classification

Energy SourceEnergy Source

• PhototrophsPhototrophs

• ChemotrophsChemotrophs

Carbon SourceCarbon Source

• AutotrophsAutotrophs

• HeterotrophsHeterotrophs

HerbivoresHerbivores

DecomposersDecomposers

1st Carnivores1st Carnivores

Top CarnivoresTop Carnivores

ProducersProducers

Ecological ClassificationEcological Classification

Producer EfficiencyProducer Efficiency

• Gross 1o Production (GPP)– GPP/Solar flux

• 0.5 – 4.0 % efficiency.

• Net 1o Production (NPP)– GPP - Respiration

– NPP/GPP• 30 - 80 % efficiency.

10,000 cal9,500 cal

500

cal

150 cal

Consumer EfficiencyConsumer Efficiency

100 cal

200

cal

100 cal50

cal

Heat

10 calGrowth/Reproduction

40 calWasteNot Eaten

Classification According to Life FormClassification According to Life Form

PhytoplanktonPhytoplankton

ZooplanktonZooplankton

Benthic invertebratesBenthic invertebrates

NektonNekton

PlanktonPlankton• Small organisms suspended in the water column, with no or Small organisms suspended in the water column, with no or

limited powers of locomotion. Plankton ranges in size from < 2 µm limited powers of locomotion. Plankton ranges in size from < 2 µm (picoplankton), 2-20 µm (ultra or nanoplankton), to >20 µm (picoplankton), 2-20 µm (ultra or nanoplankton), to >20 µm (microplankton).(microplankton).

• Phytoplankton refers to small plant plankton.Phytoplankton refers to small plant plankton.

• Zooplankton refers to small animal plankton.Zooplankton refers to small animal plankton.

PeriphytonPeriphyton

• Community of algae growing attached to substrates Community of algae growing attached to substrates (rock, plant, animal, sand).(rock, plant, animal, sand).

• The entire community of microscopic organisms The entire community of microscopic organisms (bacteria, algae, protozoa, small metazoa) is referred to (bacteria, algae, protozoa, small metazoa) is referred to as as biofilmbiofilm (‘aufwuchs’) (‘aufwuchs’)

Benthic InvertebratesBenthic Invertebrates

• Non-planktonic animals associated with substrate at Non-planktonic animals associated with substrate at the sediment-water.the sediment-water.

– Epibenthos live and move about on the lake bottom.

– Infauna are organisms that burrow beneath the mud surface.

NektonNekton• Actively swimming organismsActively swimming organisms

Neuston (‘Pleuston’)Neuston (‘Pleuston’)

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

Osborne 2000

ProkaryotesProkaryotes• Archaebacteria (archaea)Archaebacteria (archaea)

• Eubacteria (bacteria)Eubacteria (bacteria)

• DensityDensity• 1,000,000,000 / g sediment (less in water)1,000,000,000 / g sediment (less in water)

• Diversity: cDiversity: ca. 5,000 species known (millions a. 5,000 species known (millions may exist)may exist)

• Surface area : volume ratio highSurface area : volume ratio high

• 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)

• Numbers, biomass and productivity of bacterio- plankton generally increase with increasing trophic state and temperature.

Tropical aquatic systems

BacteriaBacteria

• Autotrophs (examples)Autotrophs (examples)

* Purple sulfur bacteria* Purple sulfur bacteria (anaerobic:CO2 + H2S CH2O + S)

* Green sulfur bacteria* Green sulfur bacteria (anaerobic: ditto but different light wavelength)

* Cyanobacteria * Cyanobacteria (‘blue-green algae’)

• HeterotrophsHeterotrophs. Decomposition of particulate and . Decomposition of particulate and dissolved organic matter.dissolved organic matter.

Rates of decomposition determined by chemical composition of Rates of decomposition determined by chemical composition of organic matter, pH, temperature, availability of electron acceptors.organic matter, pH, temperature, availability of electron acceptors.

• Parasitic.Parasitic. Significant role in the spread of water-borne Significant role in the spread of water-borne diseases (cholera, dysentery, salmonella, etc.)diseases (cholera, dysentery, salmonella, etc.)

Cyanobacteria Bloom Microcystis Anabaena

BacteriaBacteria• AutotrophsAutotrophs

* Purple sulfur bacteria* Purple sulfur bacteria (anaerobic:CO2 + H2S CH2O + S)

* Green sulfur bacteria* Green sulfur bacteria (anaerobic: ditto but different light wavelength)

* Cyanobacteria * Cyanobacteria (‘blue-green algae’)

• HeterotrophsHeterotrophs. Decomposition of particulate and . Decomposition of particulate and dissolved organic matter.dissolved organic matter.

Rates of decomposition determined by chemical composition of Rates of decomposition determined by chemical composition of organic matter, pH, temperature, availability of electron acceptors.organic matter, pH, temperature, availability of electron acceptors.

• Parasitic.Parasitic. Significant role in the spread of water-borne Significant role in the spread of water-borne diseases (cholera, dysentery, salmonella, etc.)diseases (cholera, dysentery, salmonella, etc.)

Surface Area to Volume Ratios

Surface area (s) = 4(pi)r2

Volume (V) = 4/3(pi)r3

r = 1 µm

r = 20µm

s = 12.6 µm2

V = 4.2 µm3

= 3.0

s = 5028 µm2

V = 33520 µm3

= 0.15

Protozoa (1-2 days)

Rotifera (3-5 days)

Cladocera (7-14 days)

Copepoda (3-5 weeks)

NutrientRelease(per unitbody weight)

Body Size

small large

low

high

Turnover Rate

Surface AreaVolume

high

low

Rotifers and protozoans are often “co-blooming” with cyanobacteria in tropical waters

For a given nutrient status, primary production in the (sub)tropics is higher because

• Efficient nutrient cycling

– High density/activity of bacterial decomposers

– Importance of smaller organisms

• Greater stability in solar radiation

• Higher temperatures

– Lowland tropics

Phyto-plankton

Bacteria

CrustaceansCrustaceansA B Rotifers and ProtozoansRotifers and Protozoans

Temperate lakesTemperate lakes

BA

FishFish

Phyto-plankton

Bacteria

Tropical lakesTropical lakes

Source: Nilssen 1984Source: Nilssen 1984

BA

Importanceof grazing

Body sizeof grazer

low

high

small large

bacteria

algae

Systems dominated by bacteria abundant small grazers

Systems dominated by algae (not blue-greens) abundance of larger grazers

Role of Heterotrophic Bacteria in Food WebsRole of Heterotrophic Bacteria in Food Webs

Bacterial DecompositionBacterial Decomposition

ProtozoaProtozoa(Ciliates, Flagellates)(Ciliates, Flagellates)

Particulate organic matter

AlgaeAlgae ZooplanktonZooplankton FishFish

Nutrients

Energy

Soluble organic matter

‘Microbial loop’

Consequences:Consequences:

Protozoa may also consume cyanobacteria

Ciliates, FlagellatesCiliates, Flagellates(Protozoa)(Protozoa)

AlgaeAlgae

BacteriaBacteria

MacrozooplanktonMacrozooplankton FishFish

DOM, POMDOM, POM

Cyanobacteria

(1) Toxins become concentrated in aquatic invertebrates and passed up the food (1) Toxins become concentrated in aquatic invertebrates and passed up the food chainchain(2) Added steps in food chain decrease food transfer efficiency to higher trophic levels(2) Added steps in food chain decrease food transfer efficiency to higher trophic levels

(3) Exceptions to this decrease food transfer efficiency occur when cyanobacteria are (3) Exceptions to this decrease food transfer efficiency occur when cyanobacteria are directly consumed by higher trophic levels such as some cichlids, birds, humans (largely directly consumed by higher trophic levels such as some cichlids, birds, humans (largely restricted to tropics).restricted to tropics).

BacteriaBacteria• AutotrophsAutotrophs

* Purple sulfur bacteria* Purple sulfur bacteria (anaerobic:CO2 + H2S CH2O + S)

* Green sulfur bacteria* Green sulfur bacteria (anaerobic: ditto but different light wavelength)

* Cyanobacteria * Cyanobacteria (‘blue-green algae’)

• HeterotrophsHeterotrophs. Decomposition of particulate and dissolved . Decomposition of particulate and dissolved organic matter.organic matter.

Rates of decomposition determined by chemical composition of organic Rates of decomposition determined by chemical composition of organic matter, pH, temperature, availability of electron acceptors.matter, pH, temperature, availability of electron acceptors.

• Heterotroph Parasitic.Heterotroph Parasitic. Significant role in the spread of Significant role in the spread of water-borne diseases (cholera, dysentery, salmonella, etc.)water-borne diseases (cholera, dysentery, salmonella, etc.)

Vibrio cholerae

Tropics and the Transmission ofTropics and the Transmission ofInfectious DiseasesInfectious Diseases

• Cultural factorsCultural factors– Lower standards of hygiene and health careLower standards of hygiene and health care– Lower standard of living (e.g., refrigeration, water supply & wastewater Lower standard of living (e.g., refrigeration, water supply & wastewater

treatment)treatment)– Higher incidence of nutritional deficiencies (lower resistance)Higher incidence of nutritional deficiencies (lower resistance)– Active control of vectors in non-tropical regions (spraying, draining of Active control of vectors in non-tropical regions (spraying, draining of

wetlands, etc.)wetlands, etc.)

• Ecological factorsEcological factors– High temperatures, high humidity: Disease vectors (e.g., mosquitos, flies) High temperatures, high humidity: Disease vectors (e.g., mosquitos, flies)

are more abundant (particularly during the wet season)are more abundant (particularly during the wet season)– Increased exposure to contaminated water and soil (particularly during Increased exposure to contaminated water and soil (particularly during

the wet season)the wet season)– Vectors survive year roundVectors survive year round

Source: Sattenspiel 2000Source: Sattenspiel 2000

Bacterial Waterborne DiseasesBacterial Waterborne Diseases • Clinical FeaturesClinical Features

– Acute dehydrating diarrhea (cholera), prolonged febrile illness Acute dehydrating diarrhea (cholera), prolonged febrile illness with abdominal symptoms and malaise (typhoid fever), acute with abdominal symptoms and malaise (typhoid fever), acute bloody diarrhea (dysentery), etc.bloody diarrhea (dysentery), etc.

• Common agentsCommon agents– Vibrio choleraeVibrio cholerae, , Campylobacter Campylobacter sppspp.., , Salmonella typhi, Shigella Salmonella typhi, Shigella

spp.spp.,, and the diarrheogenic and the diarrheogenic Escherichia coliEscherichia coli..

• IncidenceIncidence– Each year, an estimated 3 million deaths (mostly among Each year, an estimated 3 million deaths (mostly among

children) result from diarrhea. Waterborne bacterial children) result from diarrhea. Waterborne bacterial infections may account for as many as half of these deaths.infections may account for as many as half of these deaths.

[More information:[More information:Centers for Disease Control, World Health Organization]Centers for Disease Control, World Health Organization]

Bacterial Waterborne DiseasesBacterial Waterborne Diseases • SequelaeSequelae

– Many deaths among infants and young children are due to Many deaths among infants and young children are due to dehydration, malnutrition, or other complications.dehydration, malnutrition, or other complications.

• TransmissionTransmission– Contaminated surface water and poorly-functioning water Contaminated surface water and poorly-functioning water

distribution systems contribute to transmission of waterborne distribution systems contribute to transmission of waterborne bacterial diseases. Chlorination, safe water handling, and bacterial diseases. Chlorination, safe water handling, and water treatment can reduce the risks of transmission. water treatment can reduce the risks of transmission.

• TrendsTrends– Improvements in water and sanitation infrastructure have Improvements in water and sanitation infrastructure have

barely kept pace with population increases and migrations in barely kept pace with population increases and migrations in the developing world. the developing world.

[More information:[More information:Centers for Disease Control, World Health Organization]Centers for Disease Control, World Health Organization]

Source: WHO

Cases of cholera reported to WHOby continent and by year, 1989-2009

Source: WHO 2010