Figu

re 1

. Lo

catio

n of

regi

ons w

ithin

no

rther

n an

d so

uthe

rn N

aple

s Bay

whe

re

side

-sca

n so

nar t

rack

s was

com

plet

ed.

20

Figu

re 2

. Lo

catio

n of

7 C

HIR

P pr

ofile

s lin

es w

ithin

nor

ther

n N

aple

s Bay

. Th

ese

prof

iles

over

lap

with

the

regi

on c

over

ed b

y th

e si

de-s

can

sona

r sur

vey.

21

Figu

re 3

. O

ne lo

ng C

HIR

P pr

ofile

(lin

e 9)

was

com

plet

ed in

sout

hern

Nap

les B

ay a

nd ru

ns

dow

n th

e ce

nter

of t

he si

de-s

can

sona

r sw

ath.

22

Figu

re 4

. A

eria

l vie

w o

f the

Ten

Tho

usan

d Is

land

s sho

win

g th

e 4

subr

egio

ns in

clud

ed in

this

st

udy:

Bla

ckw

ater

Bay

, Fak

a U

nion

Bay

, the

out

er c

oast

al m

argi

n of

Bla

ckw

ater

est

uary

, and

th

e ou

ter c

oast

al m

argi

n of

Fak

a U

nion

est

uary

.

23

Figu

re 5

. Lo

catio

ns o

f sid

e-sc

an so

nar

surv

eyed

regi

ons i

n th

e B

lack

wat

er

estu

ary

of th

e Te

n Th

ousa

nd Is

land

s: th

e in

ner r

egio

n of

Bla

ckw

ater

Bay

, whe

re

oyst

er re

ef d

evel

opm

ent p

redo

min

ates

, an

d th

e ou

ter c

oast

al m

argi

n, w

here

ve

rmet

iform

gas

tropo

d re

efs o

ccur

. Th

e lo

ng sh

allo

w st

ruct

ure

runn

ing

para

llel

and

east

of t

he o

uter

coa

stal

side

-sca

n so

nar s

wat

h (w

hich

cov

ers a

reef

s) is

a

seco

nd g

astro

pod

reef

.

24

Figu

re 6

. Th

ree

CH

IRP

lines

pro

filed

in B

lack

wat

er B

ay.

25

Figu

re 7

. Lo

catio

ns o

f si

de-s

can

sona

r sur

veye

d re

gion

s in

the

Faka

Uni

on

estu

ary

of th

e Te

n Th

ousa

nd Is

land

s: th

e in

ner r

egio

n of

Fak

a U

nion

Bay

, whe

re o

yste

r re

ef d

evel

opm

ent

pred

omin

ates

aro

und

its

perim

eter

, and

the

oute

r co

asta

l mar

gin,

whe

re

verm

etifo

rm g

astro

pod

reef

s occ

ur.

26

Figu

re 8

. Si

x C

HIR

P lin

es p

rofil

ed a

cros

s Fak

a U

nion

Bay

.

27

Figu

re 9

. Si

de-s

can

sona

r res

ults

for F

aka

Uni

on B

ay sh

owin

g 4

subs

trate

type

s: sa

ndy

mud

m

atrix

, SA

V-c

over

ed b

otto

m, i

sola

ted

oyst

er re

efs,

and

frin

ging

oys

ter r

eefs

.

28

Figu

re 1

0. S

ide-

scan

sona

r res

ults

for B

lack

wat

er B

ay sh

owin

g 2

subs

trate

type

s:

frin

ging

oys

ter r

eefs

and

sand

y m

ud b

otto

ms (

porti

ons o

f sw

aths

not

hig

hlig

hted

in

gree

n).

29

Figu

re 1

1. S

ide-

scan

sona

r res

ults

for t

he o

uter

coa

stal

mar

gin

of th

e B

lack

wat

er e

stua

ry

of v

erm

etifo

rm g

astro

pod

reef

subs

trate

. Th

e re

ef su

rfac

e is

com

pose

d of

pat

ches

of h

igh

subs

trate

with

shal

low

relie

f, in

ters

pers

ed w

ith sa

nd-a

nd g

rave

l-ric

h ar

eas.

Thi

s cre

ates

th

e pa

tchy

app

eara

nce

of th

e ac

oust

ic re

flect

ors.

30

Figu

re 1

2. S

ame

verm

etifo

rm g

astro

pod

reef

subs

trate

but

from

out

er c

oast

of F

aka

Uni

on

estu

ary.

31

Figu

re 1

3. M

ottle

d pa

ttern

seen

with

in th

e si

de-s

can

sona

r sig

nal i

ndic

ativ

e of

su

bmer

ged

aqua

tic v

eget

atio

n (S

AV

) tha

t cou

ld g

ener

ated

by

sea

gras

ses o

r ben

thic

al

gae.

Als

o pr

esen

t are

boa

t pro

pelle

r sca

rs a

cros

s thi

s hab

itat.

Imag

e m

id-li

ne

repr

esen

ts th

e to

wed

sona

r; th

e le

ft an

d rig

ht h

alve

s of t

he im

age

repr

esen

t the

por

t and

st

arbo

ard

side

s, re

spec

tivel

y, o

f the

sona

r sw

ath.

32

Figu

re 1

4. S

imila

rly fo

rmat

ted

imag

e as

seen

in F

igur

e 13

. St

arbo

ard

pane

l sho

ws

side

-sca

n so

nar i

mag

e of

a su

btid

al o

yste

r ree

f fro

m n

orth

ern

Nap

les B

ay.

33

Figu

re 1

5. C

HIR

P lin

e 4

runn

ing

para

llel t

o an

d th

roug

h B

lack

wat

er R

iver

’s m

outh

. Le

ngth

hig

hlig

hted

in g

reen

trav

erse

s mod

ern

fore

set b

eds o

f the

rive

r’s d

elta

.

34

100m

5ms

3.75

m

Blac

kwat

erLi

ne 4

Rec

ent R

iver

Mou

th D

elta

with

For

eset

Beds

in N

orth

ern

Bla

ckw

ater

Bay

and

mou

th o

f Bla

ckw

ater

Riv

er

Figu

re 1

6. C

HIR

P pr

ofile

vie

w o

f the

subs

urfa

ce u

nder

line

4 in

Bla

ckw

ater

Bay

th

roug

h th

e de

lta’s

fore

set b

eds.

Red

line

s hig

hlig

ht th

e st

ruct

ural

dip

of t

hose

fore

set

beds

. N

ote

that

fore

set d

ip a

ngle

is v

ertic

ally

exa

gger

ated

.

35

Figu

re 1

7. C

HIR

P lin

e 2

runn

ing

thro

ugh

Bla

ckw

ater

Bay

. Li

ne tr

aver

ses a

n an

cien

t riv

er

mou

th’s

del

ta (h

ighl

ight

ed in

red)

. (F

igur

e 18

show

s the

fore

set b

eds o

f thi

s anc

ient

stru

ctur

e in

the

subs

urfa

ce.)

Not

e th

e po

sitio

n an

d te

rmin

atio

n of

the

old,

now

inac

tive,

Bla

ckw

ater

ch

anne

l jus

t nor

th o

f the

red

line

segm

ent.

36

50m

5ms

3.75

m

Anc

ient

Riv

er M

outh

in S

outh

east

ern

Bla

ckw

ater

Bay

Blac

kwat

erLi

ne 2

Figu

re 1

8. C

HIR

P pr

ofile

und

er th

e an

cien

t riv

er m

outh

of l

ine

2. T

he re

d lin

es

depi

ct th

e ol

d fo

rese

t bed

s. A

ngle

is v

ertic

ally

exa

gger

ated

.

37

Figu

re 1

9. C

HIR

P lin

e 4

runn

ing

acro

ss F

aka

Uni

on B

ay.

The

flat s

ubst

rate

of t

he b

ay’s

in

terio

r mim

ics a

feat

urel

ess s

truct

ure

in th

e su

bsur

face

.

38

5ms

3.75

m

100m

Flat

, fea

ture

less

bot

tom

in c

entra

l Fak

aU

nion

Bay

Faka

Uni

on B

ay L

ine

4

Figu

re 2

0. C

HIR

P pr

ofile

vie

w u

nder

line

4 in

Fak

a U

nion

Bay

. N

ote

that

the

subs

urfa

ce la

cks v

isib

le st

ruct

ures

, ind

icat

ing

that

no

shal

low

ly b

urie

d oy

ster

re

efs e

xist

und

er th

is re

gion

of t

he b

ay’s

inte

rior.

39

Figu

re 2

1. C

HIR

P lin

e 5

runn

ing

thro

ugh

Faka

Uni

on B

ay’s

inte

rior.

As t

he fr

ingi

ng re

efs

are

appr

oach

ed a

long

the

north

ern

term

inus

of t

he li

ne, b

urie

d oy

ster

reef

s are

enc

ount

ered

.

40

100m

5ms

3.75

m

Faka

Uni

on B

ay L

ine

5

Pre

sent

Oys

ter R

eefs

Ove

rlyin

g B

urie

d R

eef i

n N

orth

ern

Faka

Uni

on B

ay

Con

trast

in S

edim

ent S

urfa

ce T

ypes

is re

cogn

ized

by

diffe

renc

e in

the

refle

ctan

ce o

f sed

imen

t su

rface

: O

n le

ft th

e se

dim

ent i

s pr

obab

ly s

andy

/mud

–m

uddy

/san

d, w

here

the

right

is h

ard

sand

s,

shel

ls, a

nd o

yste

r ree

fs.

Bel

ow th

e ha

rd s

urfa

ce re

flect

ors

(on

the

right

) you

can

see

bur

ied

reef

.

Pre

sent

Day

oys

ter r

eef

Pas

t Oys

ter r

eef

Figu

re 2

2. C

HIR

P pr

ofile

und

er li

ne 5

of F

aka

Uni

on B

ay.

Yel

low

out

lines

pre

sent

-da

y oy

ster

reef

s; re

d ou

tline

s ree

fs b

urie

d in

the

subs

urfa

ce.

41

Figu

re 2

3. C

lose

-up

imag

e of

th

e si

de-s

can

sona

r res

ults

fr

om th

e no

rther

n su

rvey

are

a of

Nap

les B

ay.

Num

erou

s na

tura

l and

ant

hrop

ogen

ic

subs

trate

feat

ures

are

in

dica

ted.

42

Figu

re 2

4. S

ide-

scan

so

nar r

esul

ts fo

r the

so

uthe

rn a

rea

of

Nap

les B

ay.

A

num

ber o

f sub

stra

te

type

s is i

ndic

ated

.

43

5ms

3.75

m

200m

Nap

les

Bay

Line

3

Ante

cede

nt g

eolo

gy 1

-3m

bel

ow p

rese

nt s

edim

ent

surfa

ce.

Pos

sibl

y ol

d ra

vine

men

tsur

face

dur

ing

a lo

wer

sta

nd in

sea

leve

l.

Figu

re 2

5. C

HIR

P pr

ofile

und

er p

ortio

n of

line

3 in

nor

ther

n N

aple

s Bay

. R

ecen

t se

dim

ents

, tho

se w

ithin

thic

knes

ses o

f 1 m

, are

rela

tivel

y fla

t-lyi

ng.

The

deep

er su

bsur

face

di

spla

ys a

n er

osio

nal r

avin

emen

t sur

face

that

was

pro

babl

y cr

eate

d du

ring

a lo

wer

stan

d in

se

a le

vel.

44

58.5

m

5ms

3.75

m

Sedi

men

t Fill

with

in th

e ch

anne

l run

ning

alo

ng th

e w

este

rn m

argi

n of

Nor

th N

aple

s B

ay

Nap

les

Bay

Line

5

Figu

re 2

6. C

HIR

P pr

ofile

resu

lts fo

r por

tion

of li

ne 5

in n

orth

ern

Nap

les B

ay.

Cha

nnel

runn

ing

alon

g w

este

rn e

dge

of su

rvey

are

a sh

owin

g de

ep c

ut a

nd c

hann

el-

infil

l sed

imen

ts.

45