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,

R2boot= 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

18 N

(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