Phytoplankton,
Macroalgae, and
Eutrophication Problems in
the Bays
Subproject # 2—Phytoplankton and Macroalgal
Studies in MD Coastal Bays
Dr. Madhumi Mitra
Associate Professor of Biological and Environmental
Sciences
Coordinator of Biology and Chemistry Education
7/18/12
E-mail: mmitra@umes.edu
ALGAE
Study of Algae--Phycology
 How are algae similar to higher plants?
 How are algae different from higher
plants?
FOSSIL HISTORY OF
ALGAE
 3.5 billion yrs ago
 Cyanobacteria—first algae
 Prokaryotes—lack membrane bound
organelles
 Later eukaryotes evolved—
mitochondria, chloroplasts, and
chromosomes containing DNA.
Similarities
 Presence of cell wall—mostly
cellulosic.
 Autotrophs/Primary producers—
carry out photosynthesis
 Presence of chlorophyll a
Differences
 Algae lack the roots, stems, leaves, and other
structures typical of true plants.
 Algae do not have vascular tissues—non
vascular plants
 Algae do not form embryos within protective
coverings.
 Variations in pigments.
 Variations in cell structure—unicellular, colonial
and multicellular forms.
PROKARYOTIC VS
EUKARYOTIC ALGAE
 Prokaryote algal cell
Prokaryotes
---No nuclear region and
complex organelles—
chloroplasts, mitochondria,
golgi bodies, and
endoplasmic reticula.
-- Cyanobacteria. Chlorophylls
are on internal membranes of
flattened vesicles called
thylakoids-contain
photosynthetic pigments.
Phycobiliproteins occur in
granular structures called
phycobilisomes.
Source: http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/Cyanobacteria.htm
Prokaryotic and
Eukaryotic Algae
 Eukaryotes
---Distinct chloroplast,
nuclear region and
complex organelles.
--- Thylakoids are
grouped into grana
granum with a
Stack of thylakoids
pyrenoid
DIVERSITY IN ALGAE
 BODY OF AN
ALGA=THALLUS
 DIVERSITY IN
MORPHOLOGY
----MICROSCOPIC
Unicellular, Colonial,
and Filamentous
forms.
Source: http://images.google.com/images
CELLULAR
ORGANIZATION
 Flagella=organs of
locomotion.
 Chloroplast=site of
photosynthesis. Thylakoids
are present in the chloroplast.
The pigments are present in
the thylakoids.
 Pyrenoid-structure associated
with chloroplast. Contains
RUBP Carboxylase, proteins,
and carbohydrates.
 Eye-spot=part of chloroplast.
Directs the cell towards light.
Source: A Biology of the Algae
By Philip Sze, third edition, WCB MCGraw-Hill
Variations in the pigment
constitution
 Chlorophylls (green)
 Carotenoids (brown, yellow or red)
 Phycobilins (red pigment-phycoerythrin
blue pigment –phycocyanin)
ECOLOGICAL DIVERSITY
 LAND---WATER
 FRESH WATER---MARINE HABITATS
 FLOATING (PLANKTONIC)—BENTHIC
(BOTTOM DWELLERS)
 EPIPHYTES
PHYTOPLANKTON




Autotrophic
Free-floaters
Microscopic
Mostly unicellular although some are
colonial and filamentous
CLASSIFICATION
 Phytoplankton
----Picoplankton-0.2 to 2µm
----Nanoplankton-2.0 to 20µm
----Microplankton-20 to 200µm
Picoplankton are important contributors to primary
productivity of plankton. Biomass in surface waters
range from 40-50Pg C/year (P=peta, and 1 Pg is
equivalent to 10 15 g).
CYANOPHYTA, CHLOROPHYTA, PYRRHOPHYTA,
CRYPTOPHYTA, CHRYSOPHYTA,
BACILLARIOPHYCEAE
LIGHT
Irradiance is inversely proportional to water depth.
COMPENSATION DEPTH --- Different species
have different compensation depths. Rate of
photosynthesis equals rate of respiration. No
production of biomass takes place. Cells below
the compensation depth are unable to grow and
deplete their resources.
NUTRIENTS
Nutrient concentrations vary in different
bodies of water.
EUTROPHY-Nutrient enrichment
OLIGOTROPHY-Low nutrient level
Macroelements-C, H, O, S, K, Ca, Mg, P, and
N.
Microelements-cofactors-Fe, Mn, Cu, Zn, Mb.
Si is required by all diatoms.
Limiting Nutrients for
Growth
 Nitrogen---N2, NH4+, NO3-, NO2-, and
urea.
 Phosphorus---Inorganic phosphate can
occur in a number of forms (HPO42-,PO43;and H2PO4 Sulfur—SO42-,H2S
NITROGEN FIXATION IN
CYANOBACTERIA
Reference:
Biology of Algae
By Sze
NITROGEN
 Nitrate is the primary source of nitrogen
utilized by algae
 Nitrate----(nitrate reductase)Nitrite--(nitrite reductase)--Ammonium.
 Ammonium is utilized in cell metabolism.
PHOSPHORUS
 Phosphate in different forms
 Organic phosphates---broken down by
phosphatases in the membrane of algae.
FLOATING AND SINKING
Photosynthesis goes up
Accumulation of polysaccharides
Buoyancy increases
Cells rise
Gas vesicles collapse
Increased vacuolation
Photosynthesis
decreases
Buoyancy decreases
Cells sink
DIVERSITY IN ALGAE
MACROALGAE
Photos are by Dr. Mitra’s Research Group. These
pictures are not to be used for any purpose without Dr.
Mitra’s approval.
WHAT ARE SEAWEEDS?
 Macroalgae found in estuarine and marine
environments.
 Non-vascular, multicellular, and
photosynthetic plants.
 Chlorophyta, Rhodophyta, and
Phaeophyceae ---wall chemistry, chloroplast
structures and pigmentation, arrangement of
flagella in motile cells, and life cycles.
 Found in polar, tropical, and temperate
waters around the globe.
WHY DO WE CARE ABOUT
SEAWEEDS?
 Primary producers-important
role in the marine trophic
structure
 Calcareous seaweeds –major
contributors to the structure of
coral reefs (they can make up
30% of the reef). Porolithon
and Lithophyllum
 Mangroves and seagrass
beds—seaweeds can provide
a rich source of food for
detritus feeders such as
fiddler crabs. These
seaweeds can also be
important food sources for
amphipods and isopods.
Gracilaria-epiphyte of Zostera marina
Photo: Dr. Mitra
WHY DO WE CARE ABOUT
SEAWEEDS?
 Seaweeds that are edible are called
“seavegetables”
 Health-promoting/medicinal properties
(treatment of cancers, heart diseases,
rheumatism, blood sugar, and flu)
 Effective fertilizers, soil conditioners, and are a
source of livestock feed
 Used in wide range of products from ice cream
to fabric dyes.
WHY DO WE CARE ABOUT
SEAWEEDS?
 Used as “biological scrubbers”—Ulva
 Gels from seaweeds—Agar is derived from red
seaweeds (Gelidium, Gracilaria, Hypnea, and
Pterocladia). It is used in microbiological
growth medium and food industry.
Carrageenans are obtained from Chondrus
and Gigartina. Alginates are found in the cell
walls of many brown seaweeds. Primary
sources are Macrocystis, Ascophyllum, and
Laminaria.
ECOLOGICAL PROBLEM
Nutrient and sediment loads
Eutrophication
Death of
organisms
Water acidification
Water quality deteriorates
Recycling of nutrients
and pollutants in the ecosystem
Anoxia
Increase
in herbivore population
Development of opportunistic and
tolerant micro and macroalgae
Photosynthesis declines
Environmental conditions become
unfavorable and algae die and
decompose
toxicity rises
Large biomass
Courtesy: Dr. Mitra
IMPACTS OF SEAWEED
BLOOMS
 Benthic macroalgae have a low C/N
content (rich in nitrogen and low in
structural carbohydrates). Their
decomposition can stimulate bacterial
activity. This can result in sediment
resuspension and high turbidity.
IMPACTS OF SEAWEED
BLOOMS
 Light availability—incident irradiation was attenuated.
PRIMARY EFFECT
 SECONDARY EFFECTS
---- Increase in ammonium concentrations within
macroalgal mats. These levels may be toxic to
eelgrass (van Katwijk et al. 1997).
----- Increase in sediment sulfide concentrations resulting
from decaying macroalgal layer. Sediment sulfide can
reduce photosynthesis.
----Anoxia. High sulfide and low oxygen concentrations
can reduce growth and production of seagrasses by
decreasing nutrient uptake and plant energy status.
TYPES OF SEAWEEDS
(MORPHOLOGICAL TYPES)






Sheet like
Filamentous group
Coarsely branched group
Thick-leathery group
Jointed calcareous group
Crustose group
SHEET GROUP
 Thin, tubular or
sheetlike.
 Soft
 Photosynthetic
activity-high
 Toughness-low
 Examples: Ulva,
Enteromorpha,
Porphyra.
Photos: Dr. Mitra’s Lab
Ulva lactuca
Enteromorpha intestinalis
FILAMENTOUS GROUP
 Delicate branches
 Texture-Soft
 Photosynthetic
activity-moderate
 Toughness-low
 Chaetomorpha,
Cladophora,
Ceramium
Ceramium rubrum
Photo: Dr. Mitra’s Lab
COARSELY BRANCHED
GROUP
 Coarsely branched
 Pseudoparenchymatous
to parenchymatous
 Texture—fleshy to wiry
 Toughness-low
 Gigartina, Chondrus,
Agardhiella
Gracilaria tikvahiae
Photos: Dr. Mitra’s lab
Agardhiella tenera
THICK LEATHERY GROUP
 Thick blades and
branches
 Texture-leathery
 Photosynthetic rate –
low
 Toughness-high
 Fucus, Laminaria,
Sargassum, Padina
Fucus vesiculosus
Photo: Dr. Mitra’s Lab
JOINTED-CALCAREOUS
TYPE
 Calcareous, upright
 Calcified segments,
flexible joints
 Texture-stony
 Photosynthetic ratevery low
 Toughness-very high
 Corallina, Halimeda
Corallina officinalis
Reference: http://seaweed.ucg.ie/descriptions/Coroff.html
CRUSTOSE GROUP
 Encrusting
 Calcified, some
uncalcified
 Texture-stony, tough
 Photosynthetic
activity-low
 Toughness-very high
 Encrusting corallines,
Ralfsia,Hildenbrandia
Hildenbrandia
Reference: http://www.guiamarina.com/chile/02%20plants/Rhodophyceae/Hildenbrandia%20sp..htm
BENTHIC MARINE ALGAEMORPHOLOGICAL TYPES



1.
2.
3.
4.
5.
6.
Which forms have the least resistance
to herbivores?
Which forms have the highest
resistance to herbivores?
Which ones are late successional
forms?
Sheet like
Filamentous group
Coarsely branched group
Thick-leathery group
Jointed calcareous group
Crustose group
NUISANCE MACROALGAL SPECIES OF THE COASTAL
BAYS
Photos: Dr. Mitra’s Lab
Assignment/Group Activity
 How will you incorporate Algae in your
curriculum?
 How will you incorporate Eutrophication
in your curriculum?