Diatoms as environmental
indicators in Barnegat Bay
Marina Potapova, Nina Desianti, David Velinsky, Paul Kiry, Linda Zaoudeh, Roger Thomas, Paula Zelanko
Academy of Natural Sciences of Drexel University
Mihaela Enache and Tom Belton
New Jersey Department of Environmental Protection
Microalgae: small in size, big in function
Biomass is relatively low
compared to marsh plants,
seagrass and macroalgae,
but produce up to 50% of all
organic matter in coastal
systems
Attached microalgae:
microphytobenthos + epiphytes
Phytoplankton
Toxic
phytoplankton
blooms
Diatoms: algae with silica skeletons
• The most abundant and diverse algae; 20% of global primary production, up to
75% of algal production in coastal zone
• Coastal benthic diatoms: nutrient dynamics, food source for invertebrates,
sediment stabilization
• Sensitive indicators of environmental conditions
• Mineralized (silica) cell wall (frustule) - preserves in sediments
Diatoms in mudlfats of the
Barnegat Bay
and snails feeding on them
Diatoms are indicators of:
- Rock age
- Salinity
- pH
- Dissolved organic matter
- Nutrients
- Metals
- General pollution
- Temperature
- Habitat
Research areas:
- Biostratigraphy
- Paleoceanography
- Paleolimnology
- Climate change
- Sea level research
- Bioassessment
Diatom
skeleton:
frustule
Goals of our study
– Develop diatom-based indicators of nutrient
enrichment in Barnegat Bay
– Explore the use diatoms as indicators of sediment
contaminants
Photo: Andrew Mills
Approach:
• Determine indicative properties of
diatoms using a calibration dataset of
110 sediment samples collected from
marshes and open water areas
• Determine how diatom assemblages
changed during the last 300-400 years
A rich diatom flora found: many of 603 diatom species
required special taxonomic investigations
-1 4
-23
AMPHalla
AMPHpediAMPHsp2
AMPHsp3
AMPHsp6
ASTAbahu
CHAEspp
COCCdisc
COCCneot
COCCpetd
COCCcfsc
COCCstau
CYCLgrac
CYCLchoc
CYCLstri
DENTsubt
FALLaequ
FALLcryp
FRAGamic
FRAGcass
HALAapon
HALAcoffMINIspp
NAVIcfko
NAVIcfmi
NAVIgreg
NAVIphya
NAVIsaliNAVIsaco
NAVIs001
NAVIs026
NAVIs005
NITZdiss
NITZpale
NITZpusi
OPEPsp2OPEPsp8
PARAsulc
PLANdepe
PLANfreq
PLANrodr
PSAMvigo
PSEUtrai
SKELspp THALnitz
THALpros
Depth
DO
pH
Salinity
Turb Cond
TSS
ChlA
PP
TDP
NH3
NO3
TN
TIN
TP
TKN
Csed
Nsed Psed
Dev
Forest
Grassland
Wetland
Ag
Undev
DevAg
DCA1
DC
A2
Multivariate analyzes to explore major gradients in diatom
assemblage composition and distribution of diatoms along
environmental gradients
• Salinity is a major
driver of diatom
assemblage composition
in coastal setting
• Among nutrient
parameters that were not
correlated with salinity,
nitrogen content of
sediments had the biggest
influence on diatom
assemblage composition
Environmental variable F-ratio P-value
Chlorophyll A, Log mg/L 2.5 0.001
Particulate Phosphorus, Log mg P/L 2.4 0.002
Total Dissolved Phosphorus, Log mg P/L 3.5 0.001
Total Phosphorus, Log mg P/L 3.1 0.001
Ammonia, Log mg N/L 2.0 0.006
Nitrate + Nitrite, Log mg N/L 2.5 0.004
Total Inorganic Nitrogen, mg N/L 2.3 0.002
Carbon sediment, Log mg/g 4.2 0.001
Nitrogen sediment, Log mg/g 4.7 0.001
Phosphorus sediment, Log mg/g 3.3 0.001
“Developed” land-use, sqrt % 2.5 0.001
Strength of the relationships
between diatom assemblage
composition and environmental
variables as measured by the
significance of the first CCA axes
* The effect of salinity is taken out
2
2.5
3
3.5
4
4.5
2 2.5 3 3.5 4 4.5
Weighted-averaging
partial-least square
inference model for
sediment N, 2nd
component:
R2 = 0.87,
R2 boot= 0.55
RMSEP = 0.30
Observed log N(mg/g)In
ferr
red
log
N(m
g/g
)
Indicator species analysis: to identify species indicative of
low or high levels of nitrogen and phosphorus
Reconstructing environmental conditions in the Bay using marsh sediment cores
Four
cores
collected
in 2009
Great Bay
core
collected in
2014
Cs-137 (dpm/g dw)
0.0 0.2 0.4 0.6 0.8 1.0
Dep
th (
cm
)
0
20
40
60
80
100
Total P (wt%)
0.04 0.06 0.08 0.10
Dep
th (
cm
)
1860
1880
1900
1920
1940
1960
1980
2000
2020
Core dating,
chemistry, pollen and diatom analyses
1600
1620
1640
1660
1680
1700
1720
1740
1760
1780
1800
1820
1840
1860
1880
1900
1920
1940
1960
1980
2000
2 6 10 14
Core BB1: diatom-based inference shows strong N enrichment from 1940s
1.4 2.8 5.6 11.2 0 2 4 6 8
Sediment N (mg/g) inferred from diatoms
Diatom-based zones
Zone 1
Zone 2
Zone 3
Zone 4
Sediment N (mg/g)
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
Dept
h(c
m)
-2000
-1980
-1960
-1940
-1920
-1900
-1880
-1860
-1840
-1820
-1800
-1780
-1760
-1740
-1720
-1700
-1680
-1660
-1640
Cale
ndar
years
10 20 30
Org
ani
c C
arb
on (
%)
-20 -10
delta
13C
(0 /0
0)
0 2 4
delta
18N
(0/0
0
20 40 60 80
AP/NAP Tsuga
Pin
us s
trobus
20
Pin
us d
iplo
xyl
on-typ
e
20 40
Querc
us
Ace
r sacc
har
inum
-type
Ace
r sacc
har
um
Cary
aC
ast
anea
Fra
xin
us p
ennsyl
vanic
a-type
Jug
lans
cin
ere
a
Jug
lans
nig
raC
orn
us c
anade
nsis
-type
Pru
nus-
type
Aln
us in
cana-type
Fagus
Ostrya/C
arpin
us
Pla
tanus
Cory
lus
Viti
sM
oru
sE
rica
ceae
Rhodode
ndro
n
Popu
lus
trem
ulo
ides-
type
Salix
Liq
uid
am
bar
Ulm
us
Betu
laFra
xin
us n
igra
-type
Ilex
Cupre
ssa
ceae
Ace
r ru
brum
Myr
ica
Nyss
aC
leth
raA
lnus v
irid
is-t
ype
Vacc
iniu
m-t
ype
Larix
Pic
ea
Apia
cea
e u
ndiff
.
Spire
a-type
Ach
ilea-type
Rosa
ceae
undiff.
Artem
isia
Chenopo
diu
m-t
ype
20 40
Poac
eae u
ndiff.
20
Am
brosi
a-typ
e
Cere
alia
Fabace
ae u
ndiff
.
Helia
nth
em
um
Iva x
anth
ifolia
-typ
e
Ranuncu
lus-type
Pla
nta
go
Rum
ex
Cirsi
um
-typ
eS
isyr
inchi
um
Menth
a-t
ype
Am
orpha
Thalic
trum
Impatie
ns
Bid
ens-
type
Iva a
nnua-typ
eA
ster-
type
20 40
Cype
raca
ceae
Equi
set
um
Spha
gnum
Spor
e (trile
te)
Lyc
opodi
um
annotinu
m
20
Monol
ete
fer
n s
pore
Osm
unda
Typha
latif
olia
Spar
gani
um
-typ
e
Alis
ma
Bra
senia
Nym
phaea
Myr
iophyl
lum
Pota
mogeto
n/T
rigl
och
in
Ruppia
maritim
a
Sagi
taria
Pedi
ast
rum
Botryo
cocc
osG
lom
us
Spor
orm
iella
Melio
laTile
tia
Pte
ridiu
m a
quili
num
20 40
Charc
oal
20
Spha
roid
al c
arb
onace
ous
partic
les
(SC
P)
PAZ
BB-1B
BB-1A
Trees and shrubs Upland herbs/forbs Wetland herbaceous AquaticsAlgae
Fungal spores
BARNEGAT BAY
Core BB-1
0.2 0.4 0.6
Total sum of squares
CONISS
Pollen zones
amb
rosi
a
1600
1620
1640
1660
1680
1700
1720
1740
1760
1780
1800
1820
1840
1860
1880
1900
1920
1940
1960
1980
2000
2 6 10 1.6 2.5 4.0 6.3 10
Core BB4: some N increase from 1800s
0 2 4 6 8
Sediment N (mg/g) inferred from diatoms
Diatom-based zones
Sediment N (mg/g)
Zone 1
Zone 2
Zone 3
Zone 4
North - South
DCA 1
DC
A 2
Temporal shift in diatom assemblage composition as revealed by
indirect ordination: increase in species associated with high sediment
nitrogen; similar trends in Barnegat Bay cores, but slightly different in
Great Bay core
The same ordination, but plot showing species and time isolines:
rate of diatom assemblage change in accelerates with time
“Reference” diatoms
-0.6 1.0
-0.4
0.8
ADLAsp3
AMPHalla
AMPHpedi
AMPHsp2
AMPHstau
BERKruti
CHAEspp
COCCdisc
COCCneot
COCCpetd
COCCcfsc
CYCLgrac
CYCLchoc
CYCLstri
DENTsubt
FALLaequ
FALLcrypFALLmarg
FRAGamicFRAGcass
HALAapon
HALAcoff
MINIspp
NAVIgreg
NAVIperm
NAVIsaco
NAVIs026
NITZdiss
NITZpale
NITZpusi
NITZsp20
NITZsp3
OPEPsp2
OPEPsp8
PARAsulc
PLANdepe
PSAMvigo
PSEUtrai
SKELspp
THALnitz
THALpros
OCP
PAH
PCB
Cd
Cu
Pb
Relationships between contaminant concentrations and diatoms are
significant; some species may serve as indicators of relatively clean
sediments or show tolerance to contaminants
Canonical Correspondence
Analysis with salinity and %
sand partialled out
CCA1
CC
A2
Conclusions
1. Coastal diatom assemblages are diverse and sensitive to environmental stressors. We identified diatom species indicative of nutrient enrichment and this information will be used to inform nutrient criteria development.
2. Analysis of the diatom assemblages from sediment cores showed that in the course of the last 400 years they were evolving towards higher abundance of species indicative of high N content.
3. “Reference” diatom assemblages that inhabited Barnegat Bay marshes prior to 1800 are now characterized and this information can be used as an important biological endpoint supporting the development of estuarine nutrient criteria.
4. Diatom assemblages in Barnegat Bay are somewhat affected by sediment contaminants and several diatom species may be used as indicators of high-quality habitats or appear to tolerate elevated contaminant levels
