Primary Productivity and Biomass Determination in a Phytoplankton Community

(c) Mr. Jeoffrey Sanga - Delos Reyes, UPLB 1

EXERCISE 5B: PRIMARY PRODUCTIVITY
AND BIOMASS DETERMINATION IN A
PHYTOPLANKTON COMMUNITY
Acos, Roy Luister Autor, Jovel
Marie
Caballes, Denisse Abbie Cadiente, Lordan
Delos Reyes, Jeoffrey Sanga Lagajino, Stephen
Samaniego, Kate

Group 1 Biocoenosis BIO 150 U-2L
2nd Semester A.Y 2011-12

Outline
2 I. Introduction
I. Definition
II. Objectives
III. Materials
IV. Study Site Description
V. Methodology
II. Analysis and Discussion
I. Light – and – Dark Bottle method
II. Algal biomass
III. Computations
I. Dissolved Oxygen Concentration
II. Carbon Fixed
III. Optical Densities
IV. Chlorophyll a Computed Amounts
III. Guide Questions
IV. Question and Answer Sanga - Delos Reyes, UPLB
(c) Mr. Jeoffrey

Primary Productivity (def.)
3

 The rate at which primary producers
assimilate solar energy in a community
(Exploring Ecology Manual)
 The rate at which biomass is produced per
unit area by plants, the primary producers. It
can be expressed either in units of energy
(e.g. J m−2 day−1) or dry organic matter (e.g.
kg ha−1 year−1) or carbon (e.g. g C m−2
year−1) (Begon, 2006).

(c) Mr. Jeoffrey Sanga - Delos Reyes, UPLB

Light – and – Dark Bottle
4
Method
 Common Ecological tool of measuring
Photosynthesis is aquatic community.
 According to Colinvaux (1986), the Original
method is devised by Gaarder and Gran
in1927 and the determination process of
Dissolved Oxygen content is measured by
titration using Potassium permanganate (or
Wrinkler Method).


Net Primary Productivity (NPP)
5

 Colinvaux (1986) defined NPP as the energy
input less respiration
 Energy left after removal of R or respiratory
heat
 Mathematically defined as NPP = GPP - R


Gross Primary Productivity
6

 Total amount of Energy fixed by
photosynthesis
 Synonymous to Energy Input (Colinvaux,
1986)


Net Amount of Oxygen Fixed
7

 Difference between Initial Amount of Dissolved
Oxygen and the Final Amount of Dissolved
Oxygen (Exercise 5A, Exploring Ecology
Manual).

Photosynthesis
 The process of conversion of Light Energy to
Chemical Energy that is being stored in the
form of Glucose or other Sugars on different
parts of the plant (Campbell, 2009).

Chlorophyll a
8

 p ho to s y nthe tic p ig m e nt tha t participates directly in
the light reactions, which convert solar energy to
chemical energy (Campbell, 2009).

Biomass
 Mass of organisms per unit area per unit of time
(Exer 5A)
 The total mass of organic matter comprising a
group of organisms in a particular habitat
(Campbell, 2009).

Objectives of the Experiment
9

 Determine net primary productivity, community
respiration and gross primary productivity in
the aquatic environment
 Perform the method of using chlorophyll a to
estimate algal biomass in a body of water
 Explain the differences between the two
microsites based on the amount of algal
biomass observed
 Explain the relationship between
phytoplankton primary productivity and algal
biomass

Materials Used:
10

 90% Acetone
 12 DO bottles (light)
 6 DO bottles (dark)
 3 – 1 L bottles
 Spectrophotometer
 Stopwatch
 Glass Grinder or mortar and pestle


Materials Used:
11

 Centrifuge
 Improvised Black Box
 15 – mL centrifuge tubes


12 Site Location and Description
Molawin Creek Location (According to Exercise 4A): 14°9.9’ N 121° 14.3’
East, UPLB
Origin: Mount Makiling
Drainage: Laguna de Bay

Aerial View
13


Aerial View
14


SHADE AREA

STUDY SITE:
MOLAWIN CREEK

15 SUNNY AREA

Area where the bottles are
16
submerged for 30 minutes.


Methodology (LDB Technique)
17


Methodology(Algal Biomass
18
Technique)


MTD. (Spectro – photometric
19
det. )


20 Computations


Table 5B.1 Dissolved Oxygen Concentration.

Dissolved Oxygen (mg/L)

Stations IB LB DBB

R1 R2 R3 MEAN R1 R2 R3 MEAN R1 R2 R3 MEAN

1 9.4 9 9.1 9.2 13.4 13 10.8 12.4 11.9 9.9 10 10.6

2 9.1 9.9 8.3 9.1 11 14.6 11.8 12.5 9 12.8 11 10.9

Table 5B.2 Computed amount of Carbon Fixed.

Computed Values from mean IB, LB and DB (mg/L) per hour
Stations GPP as Carbon fixed (mg/m³) per hour

NPP CR GPP

1 6.4 -2.8 3.6 1350

2 6.8 -3.6 3.2 1200

21 (c) Mr. Jeoffrey Sanga - Delos Reyes, UPLB

Computations for NPP, CR and GPP
Site 1 (Sunny): Site 2 (Shade):

Computations for GPP (mg/m³ per hour)
SITE 1


Table 5B.3. Data on the optical densities of replicate samples from two Table 5B.4. Compu
sites

Stations Chlorophyll a (mg/m³)
STATIONS
Site 1
MEAN MEAN MEAN 0.08 1.168
(Sunny)
Site 1 Site 2
0.005 0.006 0.011 0.04 0.576
(Shade) (Shade)
Site 2
0.007 0.002 0.013
(Sunny)

Computations for

SITE 1 SUNNY: SIT


COMPUTATIONS FOR Chl a (mg/ m³)
SIT
SITE 1 SUNNY


GUIDE QUESTIONS
25

 Compare the two sites based on the value of a) NPP,
b) CR and c) GPP. What conclusions can you draw
from the results in each of the three variables?

 Table 5B.2 summarizes the NPP, CR, and GPP values
of the two microsites. Site/Station I has lower NPP and
higher CR while Site2 (shade) has higher NPP value
and lower CR. In the effect, the site 1 (sunny) has the
highest GPP value compared with that of shade area.
Thus, can be accounted with, in sunny area, where the
most phytoplankton reside due to abundant supply of
Oxygen.

GUIDE QUESTIONS
26

 What is the basis of the influence of substrate
composition on the NPP and the CR?
 Phytoplanktons require nutrients to survive aside from gathering
sunlight in order to survive. The more they have nutrients, the
more oxygen they can produce. This can also contribute to the
oxygen availability for the community to respire. These nutrients
are the chemical elements nitrogen and phosphorus. These
nutrients are like fertilizers to plants that enable phytoplankton to
produce proteins, nucleic acids and other parts essential for
survival and reproduction. Some phytoplankton, like diatoms,
require silicon or silicic acid in order to produce siliceous shells
that are part of their outer covering. Phytoplankton also need
trace metals like iron, copper, zinc and cobalt. The substrate is
the main source of these nutrients. Due to the weathering of
rocks, the nutrients are chipped of and are readily used by
phytoplankton. Sandy areas have a fine composition and thus
having ready-to-use nutrients. Unlike to those of the rocky areas,
the nutrients are few because of Reyes, UPLB
(c) Mr. Jeoffrey Sanga - Delos
the minerals that are not yet
weathered.

GUIDE QUESTIONS
27

 What other environmental factors may have influenced the results but were not addressed in
the experiment? Explain why such factors would play a role in the rate of photosynthesis.

 These results were influenced by the following environmental factors,
type and concentration of organisms, age of the community, amount of
nutrients and depth. There are three types of organisms observed in this
study, producers such as phytoplankton which includes microscopic algae
and photosynthetic bacteria; consumers such as zooplankton and
heterotrophic protists and decomposers which feeds on detritus.
In relevance to the type of species, producers are the sole source of
primary productivity in a community while all organisms present in a
community contribute to respiration. As defined by Odum (1971), primary
productivity is the rate at which radiant energy is stored by photosynthetic
and chemosynthetic activity of producers in the form of organic
substances. The concentration of organism also affect the productivity of
a community, a high concentration such as phytoplankton biomass would
increase productivity while an increase in heterotrophic organism would
favor respiration and a decrease in productivity as grazing would be
dominant. Wurts (2001) emphasized that both phytoplankton and
zooplankton have high metabolic rates and respiratory rates as a function
of their size and high surface to volume ratio. The age of the community
is also a determinant factor, a -youngReyes, UPLB would have a higher rate
(c) Mr. Jeoffrey Sanga Delos community
of photosynthesis than an aged one. Thus, the age of the community is

Continuation.
28

 Other factors include nutrient availability and depth. Nutrients are essential
for phytoplankton growth and reproduction. The lack of these essential
macro- and micronutrients would hinder growth, metabolism as well as
productivity. Wurts (2001) noted that phytoplankton growth is stimulated by
concentration of nitrogen and phosphorus. However, excessive amount
could also bring ill-effects to the community because each species of
phytoplankton has a particular response to different concentrations of
limiting nutrients. Ponds such as the ones used in the study, artificial ponds,
are classified according to nutrient concentrations – those with highest
concentrations and productivity are called eutrophic waters, while those
with the lowest concentrations and productivity are oligotrophic and those
that are intermediate are mesotrophic. (Smith and Smith, 1998) Hence,
there is a direct relationship between nutrient availability and productivity.
 Depth also exists as a determinant factor in aquatic system productivity. It
is a fact that light is a vital factor in photosynthesis and light quantity
declines with depth. An inverse relationship exists between depth and light.
Depth α(c) Mr.1 /Primary Productivity UPLB Depth α
Jeoffrey Sanga - Delos Reyes, and 1 /Light

Continuation.
29

 However, light is not always directly related to photosynthetic activity,
because harmful rays such as UV are present in the surface which causes
photoinhibition among surface phytoplankton thus to limit surface
productivity. In relation to depth, surface productivity is limited by light and
low nutrient availability. It gradually increases and declines to a point
called compensation depth, where productivity is equivalent to the rate of
respiration. The compensation depth is also the end of the euphotic zone or
the zone of primary productivity, in which photosynthetic activity is highly
observed.
Significantly, Wurts (2001) noted that in an aquatic system, the
environmental carrying capacity still persist as the biological limit for pond
productivity and the availability of dissolved oxygen is the major
determinant of pond biomass. Wurts also noted that nutrient availability
and light exist as important factors in the productivity of aquatic systems.
However, as phytoplankton density increases too much, light would be
limited in the surface and could cause changes in the total pond
productivity. This would also limit photosynthetic oxygen production even
though respiration continuously increases.

GUIDE QUESTIONS
30

 Compare the algal biomass in the two stations.
 Algal Biomass is higher in sunny area near the riffle / rocky
boulders, shallow area
 Chlorophyll provides an estimate for measuring algal weight and
volume, and acts as an empirical link between nutrient
concentration and other biological phenomena in
aquatic ecosystems. Nutrients and other chemicals in a
watershed, together with factors such as temperature and light,
affect the biomass production of algae in streams and lakes. Algal
production, in turn, affects the entire biological structure of an
ecosystem.
CHL a provides a measure of the amount of active algal biomass
(as periphyton) present per area of stream bottom, or a measure
of
phytoplankton from a volume of water. CHL a is a photosynthetic
pigment present in all green plants and occurs in the chloroplast
of most plant Mr. Jeoffrey Sanga - Delos Reyes, UPLB
(c) cells.
http://water.usgs.gov/owq/FieldManual/Chapter7/7.4.pdf

GUIDE QUESTIONS
31

 Was there any evident parallelism in the results
obtained in the biomass determination and the
NPP and/or GPP? Explain why there were / were
not parallel.

YES, the results obtained show that the amount of
biomass and NPP/GPP value of sunny area has
higher value compared to the shady area because
of the large amount of sunlight that affects the rate
of photosynthesis. Therefore, the higher the
NPP/GPP value, the higher the amount of
biomass.

GUIDE QUESTIONS
32

 Why are the photosynthetic rates and algal
biomass measured from the amount of
chl(orophyll) A considered as functional attributes
of a phytoplankton community?
 Phytoplankton serve as a food source in the aquatic environment.
They undergo photosynthesis in order to be able to produce food.
Photosynthetic rates and algal biomass are important functional
attributes of a phytoplankton community because these factors
help in determining things about food production in the
community. Since they undergo photosynthesis in order to
produce food, knowing the photosynthetic rate would help in
knowing how fast food is produced in the community. Algal
biomass provides a useful measure of the production and use of
resources in the community. It also determines how much of the
food is left for the next level of organism in the aquatic food chain.
(Source, n.d)?
 Algal Biomass measured is a functional attribute since it will determine

So, Why is the sea BLUE?
33

 Two way answer (proven to be valid).

 1. Physicist Answer
 2. Biologist or Ecologist Answer


References/Literature Cited
34

 Berkman Hambrook, J.A. and M.G.Canova (n.d.) A a l lg
Bio m a s s I ic a to rs . Retrieved March 06, 2012 from
nd
http://water.usgs.gov/owq/FieldManual/Chapter7/7.4.pdf
 Campbell, N. A. et. al. 2009. Bio lo g y . 8th ed. San
Francisco, CA: USA. Pearson’s Benjamin Cummings,
Inc.
 Colinvaux. P. 1986. Ec o lo g y . 1st ed. USA: John Wiley
and Sons, Inc.
 Cuevas, V.C. et. al. 2010. Ex p lo ring Ec o lo g y : La bo ra to ry
M nua l. Environmental Biology Division, Institute of
a
Biological Sciences, CAS, UPLB.
 Spokes, L. Phy to p la nkto ns a nd N utrie nts in the O c e a ns .
Retrieved March 7, 2012 from

35
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Primary Productivity and Biomass Determination in a Phytoplankton Community

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