Phosphorus and eutrophication in the Pamlico River Estuary: A summary

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THE UNIVERSITY

OF

NORTH

CAROLINA

W A T E R R E S O U R C E S R E S E A R C H

INSTITUTE

Office of the Director 124 Riddick Building

North Carolina State University Raleigh, North Carolina, 27607 Telephone: 919:755-2815

May 15, 1972

TO WHOM

I T IUY CONCERN

-

SUBJECT: P r o j e c t B-004-NC

"Phosphorus and E u t r o p h i c a t i o n i n t h e Pam1 i c o River E s t u a r y

-

A Summary Reportt'

The a t t a c h e d r e p o r t summarizes f i n d i n g s of a t h r e e - y e a r s t u d y of t h e e f f e c t s of phosphorus on t h e ecology of t h e Pamlico R i v e r E s t u a r y by

Dr.

B. J, Copeland and

Dr.

John

E,

Hobbie, Department of Zoology, North C a r o l i n a S t a t e U n i v e r s i t y , E a r l i e r r e p o r t s f o r t h e p r o j e c t were:

No, 33: "Phosphorus C o n c e n t r a t i o n s

i n

t h e Pamlico S i v e r E s t u a r y of North Caaroll.na"

No. 39: "f2ydragxaphy af

I&Ee

PaaZbc~

Rivex Ea@wary,

North C a r o l i n a "

No, 56: "Phytoplankton S p e c i e s and P o p u l a t i o n s i n t h e Pamlico R i v e r ' E s t u a r y o f North Carolina"

Your a t t e n t i o n i s c a l l e d t o t h e Summary, C o n c l u s i o n s , and Recommendations on pages 1-4, 'We t h i n k you w i l l f i n d t h i s informa- t i o n of c o n s i d e r a b l e i n r e r e s t r e l a t i v e t a p l a n n i n g and management of t h e Pamlico R i v e r Estuary and similar b o d i e s of e s t u a r i n e w a t e r s i n t h e C o a s t a l Zone of North C a r o l i n a .

David

M,

Howells D i r e c t o r

DIIH

: p Attachment

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PHOSPHORUS AND EUTROPHICATION

I N THE PAMLICB RIVER ESTUARY, N. C,

,

1966-1969

-

A SUMMARY

B e J . Copeland & John E . Hobbie Department of Zoology North C a r o l i n a S t a t e U n i v e r s i t y

R a l e i g h , N. 6 .

The work upon which t h i s p u b l i c a t i o n i s based was s u p p o r t e d i n p a r t by f u n d s provided by t h e O f f i c e of Water Resources R e s e a r c h , Department of I n t e r i o r , t h r o u g h t h e Water Resources Research I n s t i t u t e , The U n i v e r s i t y of North C a r o l i n a , a s a u t h o r i z e d under

t h e Water Resources Research Act of 1964. Matching f u n d s and o t h e r s u p p o r t were pro- vided by t h e Texas Gulf Sulphur Company. A d d i t i o n a l f u n d s and f a c i l i t i e s were

p r o v i d e d by t h e F e d e r a l Water P o l l u t i o n C o n t r o l A d m i n i s t r a t i o n and t h e N , 6 . S t a t e U n i v e r s i t y A g r i c u l t u r a l Experiment S t a t i o n .

OWRR P r o j e c t No. B-004-NC

Agreement No. 14-01-0001-1038, PY 1969

C o n t r i b u t i o n No. 23, Pamlico Marine L a b o r a t o r y , N. C. S t a t e U n i v e r s i t y , R a l e i g h .

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TABLE OF CONTENTS

ABSTRACT

LIST

OF

FIGURES

LIST OF TABLES

I. SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

I. A. Summary and Conclusions

I.

B, Recommendations

11, INTRODUCTION

11. A, Objectives

11, C, The Pamlics River Estuary

111, SUMMARY OF WORK

111, A, Hydrography

111, A.

P *

Procedures

111, A. 2, Salinity

111,

A.

3 * Temperature

111, A,

4,

m o l v e d Oxygen

111, A,

5,

Conclusions

111, B , Phosphorus

111, B. l o Procedures

111, B , 2. Phosphorus in the Water

111. B. 3. Phosphorus in the Sediments

111. B,

4,

Conciusiona

111, C, Phytoplankton

111, C.

1,

Procedures

111. C , 2, Summary of Phytoplankton

111. C,

3,

GoncEusions

111, D. Phosphorus Exchange and Sediments

111. D, 1, Procedures

111. D, 2,

i

.-

Page

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111. D. 3 , Phosphorus Effects onMortality and Growth

of Rangia Clams - , c

-

- : 6 7 ,

111. D, 4 , Accumulation of Phosphorus by Rangia Clams 49

111, D. 5 . Conclusions 50

111. E. Phytoplankton Response to Phosphorus Additions 5 3

111. E. 1, Procedures 5 3

111. E . 2. Primary Productivity in the Pamlico River Estuary

58

111.

E.

3 , Exparimenfa1 resGlts of Slime Pond Waste Additions

62

111, E.

4.

Nutrient Addition Studies

7

1

111. E.

5.

Conclusions 74

IV, DISCUSSION 7 6

IV. A. Changes in Phosphorus Concentrations

IV, B e Phytoplankton Response

IV. C, Comparison with Other Estuaries

IV.

D.

Management Problems

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ABSTRACT

A project was initiated in 1966 to measure the effects of phosphorus

on the ecology of the Pamlico River Estuary, N. C. Field surveys were

conducted to determine hydrography, phosphorus concentrations in the water

and sediment, and phytoplankton speciation and biomass in relation to

inputs from the Tar River Basin and phosphorus mining activities, Laboratory

and experimental studies were designed to determine phytoplankton response

to phosphorus additions, phosphorus exchange with sediment, phosphorus

utiliiatfcin, by Rangia clams, and phosphorus uptake by phytoplankton,

The Pamlico River Estuary is typicallyoligo- to mesohaline; tidal

influence is minimal and the estuary occasionally stratifies. This stratifi-

cation is easily destroyed by winds. During summer stratification, anaerobic

conditions develop near the bottom muds, The estuary is already rich in

phoephorus, and concentrations are increasing via land runoff and mining

wastes. Much d f the incoming phosphorus is aceunulated in the bottom sediments.

The dinoflagellate, Peridinium triquetrum, dominates a large phytoplankton

bloom that develops during the winter, apparently in response to nitrogen buildups.

The annual cycle of phyropiankton numbers and biomass in the PamPico River

Estuary is similar to that found in other similar east-coast estuaries.

Experimentation revealed that mud would remove significant afnounts sf dissolved

reactive phosphorus from the water column. There was a release of phosphorus from

the mud under low oxygen conditions, High concentrationst of phosphorus in clay-silt

sediments increased the unfavorableness of that substrate for growth and survival

of Rangia clams. The clams utilized organic matter and phosphorus from the sediments.

Limiting nutrient experiments revealed that phosphorus additions did not cause

increased carbon uptake; whereas, nitrogen additions resulted in significant

increases. Nitrogen, therefore, is the limiting major nutrient in the Pamlico

River Estuary. Although no direct effects of slime pond wastes on the estuary could

be detected, luxury uptake of phosphorus by phytoplankton and changes in phytophankton

speciation (increased blue-green algae? were experimentally observed.

i i i

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L I S T OF FIGURES

1, L o c a t i o n o f p h o s p h a t e m i n i n g o p e r a t i o n s and l o c a t i o n i n r e l a t i o n t o

N.

C. c o a s t a l zone.

2. P a m l i c o R i v e r E s t u a r y , showing series o f s t a t i o n s f o r e a r l y s t u d i e s o f p h o s p h o r u s e f f e c t s ( l e t t e r s ) and h y d r o g r a p h i c s a m p l e s ( n u m b e r s ) ,

3 . Diagram of e s t u a r y , showing s t a t i o n s f o r Mar 1967-Feb 1968, 8

4 ,

Diagram of e s t u a r y , showing s t a t i o n s f o r J u n e 1968-July 1969. 8

5, Water f l o w ( c u b i c f e e t p e r s e c o n d ) i n t h e T a r R i v e r a t T a r b o r o ,

N.

C , and i n Durham C r e a k n e a r Edward,

N.

C. Arrows i n d i c a t e

s a m p l i n g d a t e s . 14

6. Wind s p e e d and d i r e c t i o n a t t h e Texas Gulf S u l f u r Company n e a r A u r o r a ,

N.

6 .

7. S u r f a c e p r o f i l e s ( i n p p t ) i n t h e P a m l i c o R i v e r E s t u a r y : a . 29 J a n u a r y 1968

b , 1 3 J u l y 1967

c, 14 November 196%

8 , D i s s o l v e d oxygen c o n c e n t r a t i o n s ( m l / l i t e r ) i n t h e P a m l i c o R i v e r E s t u a r y ;

a . s u r f a c e , 26 F e b r u a r y 1969 b e s u r f a c e , 4 J u l y 1969 c. b o t t o m ,

4

J u l y 1969

9, The means a n d r a n g e s f o r t h e t o t a l u n f i l t e r e d p h o s p h o r u s

( u g - a t ~ B l i t e r ) i n three straga o f the P a m l i c o R i v e r , 1967-1969. The u p p e r s e c t i o n ( c l o s e s t t o W a s h i n g t o n ,

N.

C,) c o n t a i n s S t a t i o n s 1-6 (1967-1968) and H9, 10, 11, 1 6 , 1 7 , (1968-1969). The m i d d l e s t r a t u m c o n t a i n s t a t i o n s 11-35 (1967-1968) and H4-7 (1968-1969). The l o w e r s t r a t u m c o n t a i n s t a t i o n s 36-39 (1967-1968) and

K1-3 (1968-19693. 27

10. A v e r a g e b i o m a s s and numbers o f p h y t o p l a n k t o n i n t h e P a m l i c o R i v e r E s t u a r y . Sampling s t a t i o n s f o r 1966-1967 i n F i g u r e 2 and f o r 1967-1968 i n F i g u r e 3 ,

11. Flow d i a g r a m of t h e e x p e r i m e n t a l a r r a n g e m e n t f o r s t u d y i n g p h o s p h o r u s e x c h a n g e w i t h t h e s e d i m e n t s ( 5 ) .

12. P h o s p h o r u s c o n c e n t r a t i o n s r e s u l t i n g from t h e r e l e a s e o f

K2HP04 t o t h e i n p u t r e s e r v o i r and e s t i m a t e d a s mean

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F

igure

13. Biomass (wet weight) of phytoplankton in the Pamlico

River on 5 January 1968, The diameter of the circles

is proportional to the cube root of the biomass (mg/l).

Page

14. Carbon-

14 uptake (mg c/m3

/ h r )

under controlled light

and temperature conditions for samples from the

Parnlico River on 8 January 6968. The diameter of the

circles is proportional to the cube root of the mg C fixed.

60

15. Biomass (wet wieght) of phytoplankton in':the Pamliso River

on 31 July &967, The diameter of the circles is proportional

to the cube root of the biomass (mg/l).

6

1

16. Carbon-14 uptake (mg @/m3/hr) under controlled light and

temperature conditions for samples from the Pamlico River

on 29 July 1967. The diameter of the circles is proportional

to the cube root of the mg

C

fixed.

6

1

17. The effect of the additions of NO3 and PO plus NO on the

uptake of carbon-14. Samples were taken from the $limes pit

(A) and from

a

point 3/4 mile away from the pit egfluent

pipe

(B) in the Pamlico River Estuary.

7

3

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LIST OF TABLES

T a b l e s

Exchange r a t i o s and h a l f - l e f e v a l u e s e s t i m a t e d f o r volume segments w i t h i n s e c t i o n s of t h e Pamlico R i v e r E s t u a r y when f r e s h w a t e r i n f l o w averaged 42 x 105 m 3 / t i d a l c y c l e (99.1 m3/sec) ( 3 5 ) .

P e r c e n t s a t u r a t i o n of d i s s o l v e d oxygen a t t h e s u r f a c e (S) and bottom

(B)

of t h e Pamlico R i v e r E s t u a r y

13 December 1968

-

4 J u l y 1969.

Some samples from 1965 d a t a of t h e c o n c e n t r a t i o n of r e a c t i v e

. "

phosphorus ( u g - a t liter) i n t h e Pamlico R i v e r (See F i g u r e : 2 f o r l o c a t i o n of s t a t i o n s ) .

Phosphorus c o n c e n t r a t i o n s i n s u r f a c e sediments of t h e

Pamlico R i v e r E s t u a r y , o f f Texas Gulf Sulphur and o f f s l i m e s pond, 1968. C o n c e n t r a t i o n s a r e r e p o r t e d a t u g - a t ~ / m g d r y w e i g h t

of s e d i m e n t .

Net mass t r a n s p o r t s (ug-at ~ / l i t e r / t r s u g h ) of f o u r phosphorus t y p e s ( D = d i s s o l v e d , P = p a r t i s u l a t e , R = r e a c t i v e , and

U=

u n r e a c t i v e phosphorus) i n l i v i n g - l o w l e v e l (A), l i v i n g - h i g h l e v e l d B ) , and k i l l e d - h i g h l e v e l (6) e n v i r o n m e n t s , f o r t r o u g h s with sediment ( t ) and t r o u g h s w i t h o u t sediment ( b ) ,

P o s i t i v e v a l u e s h d i c a t e d d e c r e a s e of phosphorus and n e g a t i v e v a l u e s increase s f phosphorus i n t h e t r o u g h s . Values were c a l c u l a t e d u s i n g formula developed by Davis ( 5 ) .

S t u d e n t ' s v a l u e s c a l c u l a t e d f o r n e t mass t r a n s p o r t s of

f o u r phosphorus t y p e s ( 3 = d i s s o l v e d , R - r e a c t i v e , P = p a r t i c u l a t e , U = u n r e a c t i v e ) by sand and mud i n l i v i n g - l o w l e v e l ( A ) ,

l i v i n g - h i g h l e v e l

(B),

and k i l l e d - h i g h l e v e l (C)

environments. Hypotheses a c c e p t e d u s i n g the 95 percent c o n f i d e n c e i n t e r v a l ( 5 ) .

P e r c e n t m o r t a l i t y of Rangia e u n e a t a f o r sediment t y p e s and phosphorus c o n c e n t r a t i o n s (Tenore 1967).

Mean meat w e i g h t - s h e l l r a t i o sf Ramgia k u n e a t a f o r sediment t y p e s and p h o s p h o r u s c o n c e n t r a t i o n s (Tenore 1 9 6 % ) .

Average growthik s f Rangia c u n e a t a f o r sediment t y p e s and phosphorus c o n c e n t r a t i o n s ( 3 ) .

Phosphate-32 c o n t e n t of w a t e r samples from e x p e r i m e n t a l t r a y s ( c o u n t s / m i n p e r 3 ml) ( 3 ) .

A comparison of t h e Phosphate-32 c o n t e n t of a d d u c t o r

muscle t i s s u e of Rangia c u n e a t a under d i f f e r e n t t r e a t m e n t s ( T e n s r e 1967J.

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1 2 , Flow of SPW i n t o a r t i f i c i a l e s t u a r i e s and c o n c e n t r a t i o n s f Slaw and sewage i n p l a s t i c p o o l s w i t h t e m p e r a t u r e and s a l i n i t y d a t a d u r i n g t h e e x p e r i m e n t s ( C a r p e n t e r 1969).

P 4

13. I n s i t u p h y t o p l a n k t o n C a s s i m i l a t i o n e s t i m a t e s a t s i x s t a t i o n s ( F i g u r e 2) i n Pamlico R i v e r , August 1966- August 1967.

2

14. P h y t o p l a n k t o n i c primary p r o d u c t i v i t y ( i n s i t u ) i n mg/m / d a y , and a n a l y s i s of v a r i a n c e from s l i m e w a s t e a d d i t i o n s t o

e x p e r i m e n t a l e s t u a r i e s ( C a r p e n t e r 1969). 63

1%. P h y t o p l a n k t o n biomass i n a n g / l i t e r , and a n a l y s i s of v a r i a n c e from slime w a s t e a d d i t i o n s t o e x p e r i m e n t a l e s t u a r i e s ( C a r p e n t e r 1969).

5

16. C e l l numbers x 10 / l i t e r of Anabaena s p . and S p i r u l i n a s p . i n t h e a r t i f i c i a l e s t u a r i e s , w i t h a n a n a l y s i s of v a r i a n c e

and I s d t e s t among t h e t r e a t m e n t means ( C a r p e n t e r 1969). 66

2

17. A l g a l primary p r o d u c t i v i t y ( i n s i t u ) i n mg ~ / ' m /day i n t h e p l a s t i c p o o l s w i t h a n a n a l y s i s s f v a r i a n c e of

t r e a t m e n t s and a 2 x 2 f a c t o r i a l a n a l y s i s of main e f f e c t s and i n t e r a c t i o n ( C a r p e n t e r 1969).

5

18, C e l l numbers x 10 / l i t e r of Anabaena t o r ~ l o s a ~ ~ i n t h e p l a s t i c p s s k s w i t h an a n a l y s i s s f v a r i a n c e of t r e a t m e n t s and a 2 x 2 f a c t o r i a l a n a l y s i s of v a r i a n c e of main

e f f e c t s and i n t e r a c t i o n ( C a r p e n t e r 1969).

19. P h y t o p l a n k t o n biomass i n m g / l i t e r i n t h e p l a s t i c p o o l s w i t h a n a n a l y s i s of v a r i a n c e of t r e a t m e n t s and a 2 x 2

f a c t o r i a l a n a l y s i s of v a r i a n c e of main e f f e c t s and i n t e r a c t i o n ( C a r p e n t e r 1969).

20. Phosphorus u p t a k e i n u g - a t P x P ~ - ' / h r / l i t e r by microorganisms i n t h e p l a s t i c p o o l s w i t h a n a n a l y s i s

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I.

SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

I.

A, Summary and Conclusions

1. The project was designed to measure the effects of phosphorus on the ecology

of: the Pamlico River, Estuary, to predict future effects, and to suggest

alleviation methods. Field surveys were conducted to determine hydrography,

phosphorus concentrations in the water and sediment, and phytoplankton speciation

and biomass. Laboratory and experimental studies were designed to determine

phytoplankton response to phosphorus additions, phosphorus exchange with sediment,

phosphorus utilization by Ramgia clams, and phosphorus uptake by phytoplankton.

S-sme of the work was

do91

for graduate student theses,

2. The estuary is protected from the ocean by the outer banks and the tidal

influence is very small (about

0.5

feet). Water temperatures ranged between near

freezing during

the

winter and 34 C

(93

F)

during the warmest part of the summer.

Salinities are normally low (ranging between

0.5

and 15 to 20 ppt), being mainly

influenced by streamflow. Stratification exists sporadically, set up by

inflowing freshwater and destroyed by strong winds. During stratification in

the summer, anaerobic conditions develop in the middle section of the estuary.

3. The Pamlico River Estuary is naturally rich in p~ssphorus, with increasing

concentrations entering the estuary via the Tar River. These concentrations

exceed the 2.8 ug-at ~ / 1 suggested as an upper limit for unpolluted coastal

waters. The phosphorus added by Texas Gulf Sulphur Co. mining operations are

entering an estuary already rich in phosphorus.

If

nitrogen increases in the

e estuary, eutrophication problems are likely to develop,

4.

The annual cycle of phytoplankton numbers and biomass in the Pamlico River

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A l a r g e bloom of a dinoflageLlate ( P e r i d i n i u m - t r i q u e t r u m ) d e v e l o p s d u r i n g t h e

w i n t e r t i m e , b u t a p p a r e n t l y n o t i n r e s p o n s e t o phosphorus. O v e r a l l , p h y t o p l a n k t o n

d a t a i n d i c a t e t h a t t h e Pamlico R i v e r E s t u a r y i s a r i c h environment, b u t i s

i s

n o t

b e l i e v e d t h a t t h e e s t u a r y should be c o n s i d e r e d p o l l u t e d .

5. S i g n i f i c a n t mass t r a n s p o r t s of phosphorus were o b t a i n e d f o r mud, wHich

removed d i s s o l v e d r e a c t i v e phosphorus from t h e w a t e r column. T h e r e was, a l s o ,

a r e l e a s e of phosphorus from t h e mud t o t h e w a t e r under low oxygen c o n d i t i o n s .

Sediment samples o f f Texas Gulf Sulphur Co. mining o p e r a t i o n s r e v e a l e d a n

a c c u m u l a t i o n of phosphorus i n t h a t a r e a , i n d i c a t i n g t h a t t h e s e d i m e n t s s e r v e a s

a s i n k f o r incoming phosphorus, I f low oxygen c o n d i t i o n s s h o u l d d e v e l o p on a

widespread b a s i s , s i g n i f i c a n t r e l e a s e t o phosphorus from t h i s a c c u m u l a t i o n c o u l d

t a k e p l a c e ,

6. C l a y - s i l t s e d i m e n t s were found t o be more u n f a b o r a b l e f o r t h e s u r v i v a l of

RangFa clams t h e n sand s e d i m e n t s . T h i s was a t t r i b u t e d t o t h e p h y s i c o c h e m i c a l

environment a s s o c i a t e d w i t h c l a y - s i l t s e d i m e n t s . High c o n c e n t r a t i o n s of phosphorus

i n t h e s e s e d i m e n t s f u r t h e r i n c r e a s e d the a d v e r s e e f f e c t , High phosphorus concen-

t r a t i o n s i n sand s e d i m e n t s had a f a v o r a b l e a f f e c t on t h e growth of t h e clams. The

clams u t i l i z e d o r g a n i c m a t t e r and phosphorus from t h e s e d i m e n t s .

7 . No d i r e c t e f f e c t s of TGS s l i m e p o n d - w a s t e s on t h e p h y t o p l a n k t o n biomass o r

primary p r o d u c t i v i t y i n t h e Pamlico R i v e r E s t u a r y were d e t e c t e d i n o u r e x p e r i m e n t s .

The growth of b l u e - g r e e n a l g a e , however, was d i r e c t l y s t i m u l a t e d by a d d i t i o n of

s l i m e pond w a s t e . When sewage was combined w i t h s l i m e pond w a s t e , t h e r e were

i n c r e a s e d a l g a l biomass and primary p r o d u c t i v i t y .

8 . L i m i t i n g n u t r i e n t i n v e s t i g a t i o n s r e v e a l e d t h a t phosphorus a d d i t i o n s d i d n o t

c a u s e i n c r e a s e d carbotr u p t a k e . When n i t r o g e n was added, however, s i g n i f i c a n t l y

h i g h e r carbon u p t a k e was o b s e r v e d . Thus, i t was concluded t h a t n i t r o g e n r w a s t h e

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9, Luxury u p t a k e of phosphorus was observed i n e x p e r i m e n t s r e c e i v i n g s l i m e pond

w a s t e . T h i s was i n c r e a s e d by adding sewage. Thus, i f n i t r o g e n becomes a v a i l a b l e

t h e l u x u r y u p t a k e c o u l d l e a d t o u n d e s i r a b l e c o n d i t i o n s .

1. I n view of t h e low f l u s h i n g r a t e a l r e a d y p r e s e n t i n t h e e s t u a r y and t h e

low oxygen c h a r a s t e r i s t i s s d u r i n g summer s t r a t i f i c a t i o n c o n d i t i o n s , i t

i s

recornended t h a t c o n s t r u c t i o n of d i k e s o r causesways (which may d e c r e a s e t h e f l u s h i n g

e a p a c t i y o r i n t e r r u p t t h e nnorml w i n d - d r i v e n mixing p r o c e s s e s ) b e d i s c o u r a g e d .

2 . The phosphorus c o n c e n t r a t i o n s corning downstream from t h e T a r R i v e r B a s i n have

s i g n i f i c a n t l y i n c r e a s e d , I f t h i s t r e n d i s n o t r e v e r s e d , coupled w i t h TGS a d d i t i o n s

e u t r o p h i c c o n d i t i o n s saould develop o v e r t h e n e x t few y e a r s . Thus, phosphorus

a d d i t i o n s ( b o t h from upstream and mining w a s t e s ) should b e c o n t r o l l e d .

3 , S i n c e p h s s p h ~ r u s i s accumulated i n t h e s e d i m e n t s and c a n b e r e l e a s e d t o t h e

w a t e r column under low oxygen c o n d i t i o n s , f t i s reeomqended t h a t enrichment of

t h e e s t u a r y h e c o n t r o l l e d t o p r e v e n t development of a n a e r o b i c c o n d i t i o n s which

c o u l d l e a d to r e l e a s e s of s i g n i f i c a n t n u t r i e n t s from t h e sediment t o t h e e s t u a r i n e w a t e r s .

4, A p p a r e n t l y , n i t r o g e n is t h e l i m i t i n g n u t r i e n t i n t h e Pamlico R i v e r E s t u a r y . Thus, l i m i t a t i o n s o f t b e i n p u t of t h i s n u t r i e n t c a n c o n t r o l e u t r o p h i c a t i o n ,

5 , A d d i t i o n a l s t u d i e s a r e needed t o u n d e r s t a n d more c o m p l e t e l y t h e e c o l o g y of

t h e Pamlico R i v e r E s t u a r y , i t s n u t r i e n t c y c l i n g , i t s a n n u a l c y c l e s f p l a n t s and

a n i m a l s , and i t s f u t u r e :

a ) C o n t r o l l e d e x p e r i m e n t s t o d e t e r m i n e t h e n u t r i e n t r e q u i r e m e n t s of Peridinfum

t r i q u e t r u m under w a r i s u s t e m p e r a t u r e and s a l i n i t y regimes;

b ) C o n c e n t r a t i o n s of n i t r o g e n i n r e l a t i o n t o p h y t o p l a n k t o n s p e c i e s and biomass

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c ) Comparison of n u t r i e n t c o n c e n t r a t i o n s and p h y t o p l a n k t o n p o p u l a t i o n s i n t h e

Pamlico R i v e r E s t u a r y w i t h t h o s e i n t h e Neuse and Albemarle E s t u a r i e s ;

d ) I n v e s t i g a t i o n s f t h e r e l a t i o n s h i p between t h e a l g a l bloom and c o n c e n t r a t i o n s

of t r a c e m e t a l s , v i t a m i n s , and o t h e r o r g a n i c compounds;

e) Bpmparison of t h e a l g a l bloom w i t h primary p r o d u c t i v i t y and d i v e r s i t y o f o t h e r s

organisms i n t h e Pamlico R i v e r E s t u a r y ;

f ) D e t e r m i n a t i o n of s e a s o n a l d i f f e r e n c e s i n t h e t r a n s p o r t and f a t e o f n i t r o g e n

compounds t h r o u g h t h e Pamlico R i v e r E s t u a r y ;

a c t e r i z a t i o n of t h e P h y s i o l o g i c a l o p e r a t i o n s of P e r i d i n i u m t r i q u e t r u m

t o d e t e r n i n e t h e changes t o t h e e s t u a r y r e g i m e - t h a t would c r e a t e a n a l g a l

bloom d u r i n g summer; a n d ,

h ) D e s c r i p t i o n of t h e s u c c i e s s i o n a l c h a r a c t e r i s t i c s of t h e p h y t o p l a n k t o n p o p u l a t i o n

i n t h e Pamlico R i v e r E s t u a r y t o - d e t e r m i n e t h e r e l a t i o n s h i p of

-

P. t r i q u e t r u m t o

o t h e r s p e c i e s , pigment c o n c e n t r a t i o n s and r a t i o t o o r g a n i c biomass, and n u t r i e n t

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11. INTRODUCTION

11. A. O b j e c t i v e s

The o b j e c t i v e of t h i s p r o j e c t was t o measure t h e e f f e c t s of phosphorus r e s u l t i n g

from a phosphate mining o p e r a t i o n on t h e e c o l o g y of Pamlico R i v e r E s t u a r y , t o p r e d i c t

f u t u r e e f f e c t s and t o s u g g e s t a l l e v i a t i o n methods, The p r d j e c t was d e s i g n e d ~ t o

s t u d y t h e d i s t r i b u t i o n and c o n c e n t r a t i o n o f phosphorus compounds i n t h e e s t u a r y and

e f f e c t s on t h e p l a n k t o n and bottom organisms.

11. B , Background

The s t u d y was i n i t i a t e d i n 1966, s u p p o r t e d by f u n d s from t h e O f f i c e of Water

Resources Research Matching G r a n t s Program and Texas Gulf S u l f u r Company, t o s t u d y

t h e e f f e c t s of phosphorus i n t h e Pamlico R i v e r E s t u a r y . The p r o j e c t was d i r e c t e d

by D r . Donald B. H o r t o n , P r i n c i p l e I n v e s t i g a t o r . A d d i t i o n a l funds were o b t a i n e d

from t h e F e d e r a l Water P o l l u t i o n C o n t r o l A d m i n i s t r a t i o n t o s u p p o r t r e l a t e d s t u d i e s .

I n 1964, phosphate mining o p e r a t i o n s were i n i t i a t e d on t h e edge of t h e

Pamlico R i v e r E s t u a r y by t h e Texas Gulf S u l f u r Company. I t was f e a r e d t h a t t h e

phosphate mining a c t i v i t i e s would r e s u l t i n phosphorus a d d i t i o n s t o t h e e s t u a r y

and subsequent e u t r o p h i c a t i o n . Slime w a s t e from t h e phosphate p r o c e s s i n g p l a n t

was piped t o a h o l d i n g b a s i n where t h e w a t e r was allowed t o d e c a n t o f f i n t o t h e

e s t u a r y ( F i g u r e 1 ) .

It was f i r s t assumed t h a t t h e e f f l u e n t from t h e s l i m e p i t of t h e mining

o p e r a t i o n would b e a d d i n g l a r g e amounts of phosphorus t o t h e e s t u a r y , s o 6 sampling

s t a t i o n s were s e t up s t a r t i n g upstream from t h e e f f l u e n t and e x t e n d i n g about'-8

-

m i l e s downstream ( F i g u r e 2 ) . The f i r s t p a r t of t h e s t u d y was a s u r v e y , r u n e v e r y

two weeks, of t h e t e m p e r a t u r e , s a l i n i t y , oxygen, p h o s p h a t e ( 3 k i n d s ) , p h y t o p l a n k t o n ,

b

and p h y t o p l a n k t o n p r o d u c t i v i t y (with carbon-14). P a r t s of t h i s e a r l y s t u d y , f o r

example a n e s t i m a t e of t h e p h y t o p l a n k t o n primary p r o d u c t i v i t y a t 6 s t a t i o n s f o r one

complete y e a r , have been p u b l i s h e d by Copeland and Horton ( 1 ) .

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- -

F i g u r e 1: L o c a t i o n of p h o s p h a t e m i n i n g o p e r a t i o n s and l o c a t i o n i n r e l a t i o n t o

N. C . c o a s t a l z o n e .

0

POINT POINT

0

NAUTICAL M l E S

I t , , : , , ' ; I

0 6

0 2 4 G 8 1 0 1 2

I

12 1 8 2 4

K l L O M E T E R S

F i g u r e 2 : P a m l i c o R i v e r E s t u a r y , showing s e r i e s of s t a t i o n s f o r e a r l y s t u d i e s of p h o s p h o r u s e f f e c t s ( l e t t e r ) and h y d r o g r a p h i c s a m p l e s (numbers).

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I t was soon e v i d e n t t h a t t h e r e was a g r e a t d e a l o f v a r i a t i o n w i t h i n t h e r i v e r ,

a n d a l s o t h a t t h e e f f l u e n t from t h e s l i m e p i t o f t h e p h o s p h a t e mine was n o t a d d i n g

a p p r e c i a b l e amounts of p h o s p h a t e s t o t h e r i v e r . I n f a c t , i t was i m p o s s i b l e t o

m e a s u r e h i g h e r t h a n normal p h o s p h a t e l e v e l s more t h a n a few hundred meters away

f r o m t h e e f f l u e n t c a n a l . Some p r e l i m i n a r y s a m p l i n g n e a r t h e p l a n t d i d i n d i c a t e

t h a t p l a n t d i s c h a r g e i n t o Lee C r e e k (which r u n s t h r o u g h t h e m i n i n g a r e a ) was

a d d i n g l a r g e amounts of p h o s p h o r u s . The s a m p l i n g program was t h e r e f o r e expanded

t o 40 s t a t i o n s ( s u r f a c e s a m p l e s o n l y ) i n - s o m e 8 t r a n s e c t s a c r o s s t h e r i v e r b o t h

u p s t r e a m and downstream from t h e p l a n t ( F i g u r e s 3 and 4 ) . Most o f t h e same

measurements w e r e made e x c e p t t h a t t h e 4 0 p r o d ~ c t i v i t y s a m p l e s w e r e r u n u n d e r

c o n t r o l l e d l i g h t and t e m p e r a t u r e c o n d i t i o n s i n t h e l a b o r a t o r y i n s t a a d o f i n s i t u .

From t h e expanded s a m p l i n g , t h e i r r e g u l a r d i s c h a r g e o f l a r g e amounts o f p h o s p h o r u s

from t h e p l a n t c o u l d b e s e e n and t h e l a r g e p a t c h of h i g h p h o s p h a t e w a t e r c o u l d b e

f o l l o w e d a s i t moved downstream f o r n e a r l y 6 weeks. T h e r e was, however, no

c o r r e l a t i o n b e t w e e n t h e h i g h PO and a l g a l b i o m a s s o r p r i m a r y p r o d u c t i v i t y . I t

4

a p p e a r e d a s i f t h e PO4 was a c o n s e r v a t i v e f a c t o r t h a t was n o t b e i n g l o s t t o t h e

o r g a n i s m s o r s e d i m e n t s v e r y r a p i d l y . F o r t l i i s r e a s o n , i t was a good t r a c e r t o u s e

f o r w a t e r movement s t u d i e s , I t s h o u l d b e n o t e d , t h a t t h e c o n c e n t r a t i o n s o f PO 4

found w e r e o n l y r e l a t i v e l y h i g h a s t h e maximum r e a c h e d was o n l y 1 mg PO 4 p e r l i t e r .

Some o f t h e t r a n s e c t d a t a f o r PO4 c o n c e n t r a t i o n s , p h y t o p l a n k t o n b i o m a s s , and

r e l a t i v e p r i m a r y p r o d u c t i v i t y h a s b e e n p u b l i s h e d by Hobbie ( 2 ) .

S e v e r a l g r a d u a t e s t u d e n t s h a v e conducted t h e s i s p r o j e c t s i n t h e P a m l i c o

R i v e r E s t u a r y i n r e l a t i o n t o t h e e f f e c t s of p h o s p h o r u ~ ~ a d d i t i o n s . One s t u d y i n v o l v e d

t h e amount o f o r g a n i c m a t t e r and p h o s p h o r u s i n t h e s e d i m e n t s which w e r e d i r e c t l y

c o r r e l a t e d w i t h t h e g r o w t h o f t h e c l a m , R a n g i a c u n e a t a . Through t h e u s e o f Zn 6 5

t r a c e r t e c h n i q u e s i t was shown t h a t t h e c l a m s c o u l d t a k e up o r g a n i c m a t e r i a l

.

d i r e c t l y from t h e s e d i m e n t . I f t o o much o r g a n i c m a t t e r and p h o s p h a t e w e r e p r e s e n t

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STATION NUMBERS J Y

2 6 ~24 *

MAR. 1967

-

FEB. 1968

F i g u r e 3 : Diagram of e s t u a r y , showing s t a t i o n s f o r Mar 1967-Feb 1968.

S T A T l n N N I I M R F R C S H 5 H i Y

H 3 N

S H 2

- . ..

. .-..

..-

...--,,-

JUNE 1968

-

JULY 1 9 6 6 .

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work, s e a s o n a l s a m p l i n g s w e r e made of t h e whole r i v e r and t h e d i s t r i b u t i o n and

community s t r u c t u r e w e r e c a l c u l a t e d . Most of t h e b e n t h i c a n i m a l s w e r e c o n c e n t r a t e d

a l o n g t h e s h o r e s w h i l e t h e c e n t e r s f t h e e s t u a r y was a l m o s t b a r r e n , which may b e

r e l a t e d t o s e a s o n a l a n a e r o b i c b o t t o m w a t e r ( 4 ) . A n o t h e r s t u d y i n c l u d e d c a l c u l a t i o n s

o f n e t t r a n s p o r t s o f t h e removal of d i s s o l v e d r e a c t i v e p h o s p h o r u s f r o m t h e w a t e r

by mud ( 5 ) .

A p h y t o p l a n k t o n s u r v e y was c o n d u c t e d (6) which i n c l u d e d f o l l o w i n g a p h y t o p l a n k t o n

bloom w i t h d a i l y s a m p l e s f o r two and h a l f months and h o u r l y s a m p l e s f o r 24 h o u r

p e r i o d s . The d i n o f l a g e l l a t e , P e r i d i n i u m t r i q u e t r u m , dominated t h i s bloom and a t

s e v e r a l m i l l i o n p e r l i t e r . E x p e r i m e n t s wepe c o n d u c t e d t o d e t e r m i n e t h e r e l a t i o n s h i p

o f t h e p h y t o p l a n k t o n c e l l numbers and p r i m a r y p r o d u c t i v i t y t o a d d i t i o n s o f p h o s p h o r u s

t o e s t u a r i n e w a t e r s a ( 7 , 8 ) .

T h i s r e p o r t f o l l o w s a s e r i e s of t h r e e r e p o r t s on t h e p h o s p h o r u s c o n c e n t r a t i o n s

( 9 1 , h y d r o g r a p h y ( l o ) , and p h y t o p l a n k t o n s p e c i e s a n d p o p u l a t i o n s (6). A number

o f p e r s o n s h a v e h e l p e d i n t h e p l a n n i n g and d a t a c o l l e c t i o n o f t h i s p r o j e c t .

D r . Donald B . H o r t s n set u p t h e l a b o r a t o r y and was t h e p r i n c i p l e i n v e s t i g a t o r f o r

t h i s p r o j e c t . Kenneth T e n o r e , H. Lee D a v i s , David P e t e r s , Edward J . C a r p e n t e r ,

and A l b e r t S h e r k a s s i s t e d i n c o l l e c t i o n o f d a t a i n r e l a t i o n t o t h e i r t h e s i s

p r o j e c t s . James B e r r y , Henry D a n i e l s , David G o s s e t t , Johnny Pye, L i n d s a y Wood

and N i t a S c o b i e h e l p e d c o l l e c t and r e d u c e t h e d a t a .

11. C. The PamEico R i v e r E s t u a r y

The T a r R i v e r f l o w s t h r o u g h n o r t h e a s t e r n North C a r o l i n a and becomes a n

e s t u a r y a t W a s h i n g t o n , N. C.; a t t h i s p o i n t i t becomes t h e P a m l i c o R i v e r . It

t h e n f l o w s e a s t f o r some 35 miles t o e n t e r Pamlico Sound d i r e c t l y w e s t of Cape

H a t t e r a s . The maximum w i d t h i s a b o u t 8 m i l e s and t h e a v e r a g e d e p t h a b o u t 1 0 f e e t .

Most i m p o r t a n t f o r t h e c u r r e n t and t h e s a l i n i t y r e g i m e s i s t h e damping e f f e c t t h e

o u t e r banks h a v e on t h e l u n a r t i d e . A s a r e s u l t , t h i s t i d e i s a b o u t 6 i n c h e s and

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t h e w a t e r i s w e l l s t i r r e d and t h e r e i s l i t t l e o r no s t r a t i f i c a t i o n i n l a r g e p a r t s

s f t h e e s t u a r y . The s t i r r i n g a l s o keeps l a r g e amounts of p a r t i c u l a t e m a t t e r i n

s u s p e n s i o n w i t h t h e r e s u l t t h a t the e s t u a r y i s q u i t e t u r b i d most of t h e time.

The s a l i n i t y r a n g e i n t h i s e s t u a r y , from 0 to 15 p p t , i s v e r y d i f f i c u l t f o r

organisms t o a d a p t t o ; a s a r e s u l t , t h e number of d i f f e r e n t k i n d s of animals i s

s m a l l compared w i t h t h e f r e s h w a t e r s , ocean o r even Pamlico Sound ( s a l i n i t y around

20 p p t ) . The p h y t o p l a n k t o n i s dominated by a n e x t e n s i v e a l g a l bloom t h a t o c c u r s

i n January t o March of every y e a r . The dominant organisms i n t h i s bloom, t h e

d i n o f l a g e l l a t e

-,

a t t a i n s "red t i d e " numbers. The dominant

z o o p l a n k t e r i s t h e cspepod, A c a r t i a t o n s a , which i s f e d upon by l a r v a l f i s h and

by t h e ctenophore ( c o m b - j e l l y f i s h ) , Mnemiopsis l e y d i i (11). The f i s h a r e m o s t l y

s a l t w a t e r forms, a l t h o u g h f r e s h ~ . ~ p a k ~ r forms do s c o u r n e a r Washington, N. 6 . The

permanent r e s i d e n t f i s h i n c l u d e mumichog, t h e r a i n w a t e r k i l l i f i s h , t h e naked

goby, w h i t e p e r c h , t h e s t r i p e d anchbvy, American e e l , and t h e hogchoker. Another

g r o u p of f i s h i s p r e s e n t year-round e x c e p t d u r i n g w i n t e r . These i n c l u d e t h e t i d e w a t e r

s i l v e r s i d e , t h e rough s i l v e r s i d e , the cornon s i l v e r s i d e , s p o t , a t l a n t i c c r o a k e r ,

p i n f i s h , a t l a n t i c menhaden, sunmer f l o u n d e r , and t h e n o r t h e r n p i p e f i s h . O t h e r f i s h

a r e found o n l y d u r i n g t h e i r m i g r a t i o n s through t h e e s t u a r y . These i n c l u d e h i c k o r y

shad, t h e a l e w i f e , g l u t h e r r i n g , American s h a d , g i z z a r d s h a d , s t r i p e d b a s s , and

t h e c o m s n s t u r g e o n .

The b e n t h i c a n i m a l s (bottom d w e l l i n g ) a r e dominated i n t h e f r e s h e r p a r t s of

t h e e s t u a r y by t h e clam, Rangfa c u n e a t a , and i n t h e s a l t i e r p a r t s by t h e b i v a l v e ,

Macoma b a l t h i c a , I n c o n t r a s t t o many e s t u a r i e s , t h e r e i s a pronounced s e a s o n a l

change i n b e n t h i c a n i m a l s p e c i e s i n t h e PamPico R i v e r E s t u a r y ( 4 ) . T h i s i s

p r o b a b l y due t o changes i n oxygen i n t h e d e e p e r w a t e r s ,

The b l u e c r a b , shrimp, clam and o y s t e r a r e c o m e r c i a l l y h a r v e s t e d from t h e

e s t u a r y i n s i z e a b l e q u a n t i t i e s . I n a d d i t i o n , the young of many s a l t w a t e r commercial

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Although t h e r e a r e s a l t marshes i n s e v e r a l p l a c e s a l o n g t h e e s t u a r y , t h e s e

a r e h i g h marsh (Juncus s p , ) a r e a s and do n o t c o n t r i b u t e o r g a n i c m a t e r i a l t o t h e

e s t u a r y . T h i s c o n t r a s t s w i t h o t h e r a r e a s o f North C a r o l i n a c o a s t where t h e

g r e a t e r t i d a l r a n g e a l l o w s

&-

marshes t o grow (low s a l t m a r s h ) . However,

t h i s m i s s i n g o r g a n i c m a t t e r i s compensated f o r i n t h e Pamlico R i v e r by d e n s e beds

of widgeon g r a s s , R u ~ ~ i a m a r i t i m a , and P o t a m o a e x ( r o o t e d a q u a t i c p l a n t s ) . These

a r e e a t e n d i r e c t l y by w i n t e r i n g g e e s e and ducks and a l s o f u r n i s h g r e a t q u a n t i t i e s

of n u t r i t i o u s p a r t i c u l a t e m a t t e r when t h e y b r e a k up and decay i n t h e f a l l .

One of t h e r e a s o n s f o r t h e e s t a b l i s h m e n t of t h e Aurora l a b o r a t o r y was t o

s t u d y t h e expected changes caused by t h e Texas Gulf S u l f u r Company phosphate

mine and f e r t i l i z e r p l a n t . The d a t a on phosphorus c o n c e n t r a t i o n s i n t h e e s t u a r y

a r e g i v e n i n d e t a i l by Hobbie ( 9 ) , B r i e f l y , w h i l e phosphorus does e n t e r t h e

e s t u a r y , i t a p p e a r s t o have l i t t l e e f f e c t on t h e e x p e c t e d t a r g e t s i t e , t h e

p h o t o s y n t h e s i s and growth of t h e a l g a e . T h i s i s undoubtedly caused by t h e low

l e v e l s of n i t r o g e n found i n t h e e s t u a r y , I n f a c t , t h e n i t r o g e n i s p r o b a b l y l i m i t i n g

p h o t o s y n t h e s i s and a l g a e a r e n o t a b l e t o u t i l i z e a l l t h e phosphorus. Another

c o n c l u s i o n of t h e s t u d y was t h a t t h e c o n c e n t r a t i o n of phosphorus e n t e r i n g t h e

e s t u a r y from upstream (above t h e TGS s i t e ) i s i n c r e a s i n g r a p i d l y .

111. S W R Y OF WORK

We a r e summarizing i n t h i s s e c t i o n t h e major f i n d i n g s and c o n c l u s i o n s from

s e v e r a l p o r t i o n s of t h e s t u d y , B a s i c h y d r o g r a p h i c i n f o r m a t i o n h a s been g i v e n by

Hobbie ( l o ) , maps of phosphorus c o n c e n t r a t i o n by Hobbie ( 9 1 and t h e s p e c i e s and

p o p u l a t i o n of p h y t o p l a n k t o n were r e p o r t e d by Hobbie (6); V a r i o u s t h e s e s , c i t e d

e a r l i e r , c o n t a i n t h e e x p e r i m e n t a l f i n d i n g s of s e v e r a l s t u d i e s r e l a t e d t o t h i s

p r o j e c t .

A t l e a s t f o u r d i f f e r e n t s e r i e s of s t a t i o n s have been used d u r i n g t h e s t u d y

Maps showing t h e S t a t i o n numbers p r i o r t o March 1967 i n c l u d i n g t h e l e t t e r s e r i e s

(24)

Station numbers for March 1967 through February 1967 and for June 1968 through

July 1969 are given as Figures 3 and

4.

111. A. Hydrography

Hydrography of an estuary

(lee.,

the temperature, salinity, dissolved oxygen

and river flow rates) are basic to the understanding of the ecology. Along with

phosphorus, phytoplankton and productivity measurements in the Pamlico River

Estuary, routine measurements were made of the temperature, salinity and dissolved

oxygen at all sampling stations during all sampling times.

111. A. 1. Procedures

During the sampling period reported here, hydrographic samples were usually

taken at two-week intervals. A

conductivity

bridge with built-in thermistor

(Beckman RS5-3 Induction Salinometer) was used to measure salinity and temperature

in situ (except for a few times when hydrometers were used to determine salinity).

--

Water

samples for dissolved oxygen were taken with a kemmerer sampler, fixed

in the field and titrated in the laboratory (12). In order to calculate the

saturation value for the oxygen in the waters of various salinities, the equation

developed by Truesdale and Gameson (13) was used. This formula, as modified by

Neal E. Armstrong (personal communication), is:

where CS is the saturation value for oxygen (mg/liter) at the given temperature

and salinity, S is salinity (ppt), and T is tenperature (C). The mg 02/liter

times 0.7 equals the ml/liter used in this and earlier reports,

The only river flow data from the Pamlico River area are those of the

U. S, Geological Survey (Annual Reports of the Water Resource Division, U.S.G.S.,

(25)

u p s t r e a m f r o m W a s h i n g t o n , N. 6. ( t h e w e s t e r n end of t h e e s t u a r y ) . . T h i s h a s a

w a t e r s h e d o f 2 , 1 4 0 s q u a r e m i l e s . The o t h e r s t a t i o n i s o n Durham C r e e k , n e a r Edward,

N . C . , a b o u t 6.7 m i l e s s o u t h o f t h e e s t u a r y . T h i s c r e e k h a s a d r a i n a g e b a s i n of

o n l y 2 1 s q u a r e miles and e n t e r s t h e e s t u a r y j u s t t o t h e w e s t o f t h e Texas Gulf

S u l f u r Company p l a n t .

The wat!er f l o w i n t h e two b o d i e s o f w a t e r was g e n e r a l l y a l i k e i n b a s i c

c h a r a c t e r i s t i c s , b u t d i f f e r e d a t many p a r t i c u l a r p o i n t s ( F i g u r e 5 ) . T h e s e

d i f f e r e n c e s r e s u l t from l o c a l s t o r m s a t t h e s e w i d e l y s e p a r a t e d s t a t i o n s , p l u s

t h e l a g e f f e c t s o f a l a r g e v e r s u s a s m a l l w a t e r s h e d .

The w a t e r f l o w , r e f l e c t i n g d i r e c t l y t h e r a i n f a l l p a t t e r n , was i r r e g u l a r a t

b o t h s t a t i o n s ; t h e r e w a s , however, more f l o w d u r i n g t h e w i n t e r . High f l o w

p e r i o d s i n t h e T a r R i v e r w e r e : 1967 i n l a t e F e b r u a r y , end o f A u g u s t , e a r l y

S e p t e m b e r , December; and i n 1968 i n J a n u a r y and a t t h e end of March. F o r Durham

C r e e k h i g h f l o w o c c u r r e d i n : 1967 i n m i d - F e b r u a r y , J u l y , A u g u s t , S e p t e m b e r , and

December; and 1968 i n J a n u a r y , mid-March and t h e b e g i n n i n g of J u n e .

The wind speed and d i r e c t i o n f o r t h e p e r i o d 1967-1969 were p r o v i d e d by Texas

Gulf S u l f u r Company o b s e r v a t i o n s . The d a t a a v a i l a b l e i n c l u d e d h o u r l y wind s p e e d

and d i r e c t i o n measurements a s w e l l a s o t h e r s t a n d a r d m e t e o r o l o g i c a l o b s e r v a t i o n s .

F o r t h e p u r p o s e o f t h i s r e p o r t , t h e t o t a l wind movement p e r d a y ( m i l e s ) and t h e

p r e v a i l i n g d i r e c t i o n of t h a t wind h a v e b e e n a b s t r a c t e d ( F i g u r e 6 ) . The d i r e c t i o n

0 0

i s g i v e n i n d e g r e e s , w h e r e 0 i s a wind from t h e N o r t h , 90 i s f r o m t h e E a s t , e t c .

U n f o r t u n a t e l y , t h e wind d i r e c t i o n r e c o r d i n g e q u i p m e n t was n o t o p e r a t i n g d u r i n g t h e

f i r s t f i v e months o f 1967.

The a v e r a g e wind s p e e d , based upon t o t a l e l a p s e d m i l e s p e r d a y , a p p e a r s t o

b e much l e s s t h a n t h e 10 mph s u g g e s t e d a s a n a v e r a g e f o r t h e main c o a s t l i n e

( 1 4 ) . I f t h e a v e r a g e w e r e 10 mph, t h e n t h e t o t a l p e r d a y would b e 240 m i l e s and

t h i s i s c e r t a i n l y much h i g h e r t h a n t h e v a l u e s i n F i g u r e 6. O f c o u r s e , t h e two

(26)

F i g u r e 5: Water f l o w ( c u b i c f e e t p e r s e c o n d ) i n t h e T a r R i v e r a t T a r b o r o , N. C.

and i n Durham Creek n e a r Edward, N. C. Arrows i n d i c a t e s a m p l i n g d a t e s .

(27)
(28)

a l l comparable. F o r t h i s summary, c o n c e r n i s o n l y w i t h t h e s t r o n g winds t h a t

would be c a p a b l e of d i s t u r b i n g t h e s t r a t i f i c a t i o n i n t h e e s t u a r i n e w a t e r s , and

t h e s e would a p p e a r h i g h i n a r e l a t i v e s e n s e even i f t h e r e were e r r o r s , I t i s o b v i o u s ,

however, t h a t t h e p e r i o d s d u r i n g t h e y e a r of h i g h winds were t h e w i n t e r and s p r i n g

months, Only once d u r i n g t h e t e n summer months observed were t h e r e any winds

g r e a t e r t h a n a t o t a l of 190 miles. S t r o n g e r winds began a p p e a r i n g i n November and

December and c o n t i n u e d t h r o u g h May. However, d u r i n g t h i s p e r i o d o f : o b s e r v a t i o n

t h e r e were no s e v e r e summer o r f a l l h u r r i c a n e s , The wind d i r e c t i o n i s much more

d i f f i c u l t t o d e s c r i b e a c c u r a t e l y i n a r e p o r t , b u t i t a p p e a r s t h a t t h e s t r o n g

winds were o u t of t h e NE and

NW.

The p r e v a i l i n g winds f o r t h e whole of Nozth

C a r o l i n a a r e SW, e x c e p t t h a t i n September and O c t o b e r , t h e p r e v a i l i n g winds a r e NE

( 1 4 ) . T h i s change of d i r e c t i o n i n t h e autumn r e s u l t s from p e r s i s t a n t h i g h p r e s s u r e

o v e r t h e n o r t h e r n s t a t e s and a g r e a t e r number of low p r e s s u r e storms p a s s i n g o f f

North C a r o l i n a . The e f f e c t of t h e s e s t r o n g winds w i l l b e d i s c u s s e d l a t e r i n t h e

s e c t i o n on s a l i n i t y changes.

11, A . 2, S a l i n i t y

The e s t u a r y i s p r o t e c t e d by Pamlico Sound and t h e O u t e r Banks s o t h a t t h e

d i u r n a l t i d a l a m p l i t u d e a v e r a g e s l e s s t h a n 0.5 f e e t . The f l u s h i n g r a t e i s

c o r r e s p o n d i n g l y low ( T a b l e 1 ) and i n t r a i n e d p a r t i c l e s t e n d t o remain i n the

e s t u a r y f o r l o n g p e r i o d s of t i m e .

T a b l e 1, Zxchange r a t i o s and h a l f - l i f e v a l u e s e s t i m a t e d f o r volume segments w i t h i n s e c t i o n 5 of t h e Pamlico R i v e r E s t u a r y when f r e s h w a t e r i n f l o w a v e r a g e d 42 x 1 0 r n 3 / t i d a l c y c l e (99.1 m3/sec). ( 1 5 ) .

S e c t i o n Length of Number of Average ~ a l f - l i f e /

S e c t i o n V o lume ,Exchange Segment

( m i l e s ) Seamen t s R a t i o ( t i d e s )

Washington t o Rurnley Marsh

Rumley Marsh t o

I n d i a n I s l a n d 1 0 , 8 2 .082

I n d i a n I s l a n d t o

(29)
(30)

a l l comparable. For t h i s summary, concern i s o n l y w i t h t h e s t r o n g winds t h a t

would be c a p a b l e of d i s t u r b i n g t h e s t r a t i f i c a t i o n i n t h e e s t u a r i n e w a t e r s , and

t h e s e would a p p e a r h i g h i n a r e l a t i v e s e n s e even i f t h e r e were e r r o r s , I t i s o b v i o u s ,

however, t h a t t h e p e r i o d s d u r i n g t h e y e a r of h i g h winds were t h e w i n t e r and s p r i n g

months, Only once d u r i n g t h e t e n summer months observed were t h e r e any winds

g r e a t e r t h a n a t o t a l of 190 m i l e s , S t r o n g e r winds began a p p e a r i n g i n November and

December and c o n t i n u e d through May. However, d u r i n g t h i s p e r i o d b f c o b s e r v a t i o n

t h e r e were no s e v e r e summer o r f a l l h u r r i c a n e s , The wind d i r e c t i o n i s much more

d i f f i c u l t t o d e s c r i b e a c c u r a t e l y i n a r e p o r t , b u t i t a p p e a r s t h a t t h e s t r o n g

winds were o u t of t h e NE and Wd, The p r e v a i l i n g winds f o r t h e whole of NoEth

C a r o l i n a a r e SW, e x c e p t t h a t i n September and O c t o b e r , t h e p r e v a i l i n g winds a r e NE

( 1 4 ) , T h i s change of d i r e c t i o n i n t h e autumn r e s u l t s from p e r s i s t a n t h i g h p r e s s u r e

o v e r t h e n o r t h e r n s t a t e s and a g r e a t e r number of low p r e s s u r e s t o r m s p a s s i n g o f f

North C a r o l i n a . The e f f e c t of t h e s e s t r o n g winds w i l l be d i s c u s s e d l a t e r i n t h e

s e c t i o n on s a l i n i t y changes.

11, A . 2 , S a l i n i t y

The e s t u a r y i s p r o t e c t e d by Pamlico Sound and t h e O u t e r Banks s o t h a t t h e

d i u r n a l t i d a l a m p l i t u d e a v e r a g e s l e s s t h a n 0.5 f e e t . The f l u s h i n g r a t e i s

c o r r e s p o n d i n g l y low (TaSle 1 ) and i n t r a i n e d p a r t i c l e s t e n d t o remain i n t h e

e s t u a r y f o r l o n g p e r i o d s of time.

T a b l e 1, Exchange r a t i o s and h a l f - l i f e v a l u e s e s t i m a t e d f o r volume segments w i t h i n s e c t i o n 3

04

t h e Pamlico R i v e r E s t u a r y when f r e s h w a t e r i n f l o w a v e r a g e d 42 x 10

m

/ t i d a l c y c l e ( 9 9 , l m3/sec). ( 1 5 ) .

S e c t i o n Length of Number of Average ~ a l f - l i f e /

S e c t i o n Volume Exchange Segment

( m i l e s ) Segments R a t i o ( t i d e s )

Washington t o R m l e y Marsh

Rumley Marsh t o

I n d i a n I s l a n d 10.8 2 .082

I n d i a n I s la n d t o

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Changes i n s a l i n i t y s e a s o n a l l y s e m t o be a s s o c i a t e d w i t h v a r i a t i o n i n

f r e s h w a t e r r u n o f f ( F i g u r e 5 ) . W i l l i a m s and D e u b l e r (16) i n d i c a t e d t h a t t h i s

g e n e r a l s a l i n i t y c y c l e i s c h a r a c t e r i s t i c of North C a r o l i n a e s t u a r i e s , S a l i n i t y

i s l o w e s t d u r i n g t h e l a t e w i n t e r and e a r l y s p r i n g a s shown i n t h e t y p i c a l s a l i n i t y

map ( F i g u r e 7 a ) . T h i s d e c r e a s e i n s a l i n i t y i s c l o s e l y a s s o c i a t e d w i t h i n c r e a s e s

i n t h e f l o w r a t e i n t h e T a r R i v e r ( F i g u r e 5 ) , The s a l i n i t y i n c r e a s e s t o maximum

v a l u e s d u r i n g t h e summer and f a l l ( F i g u r e s 7b and 7 c , r e s p e c t i v e l y ) . These lower

s a l i n i t y v a l u e s c o r r e s p o n d t o low r i v e r f l o w r a t e s { F i g u r e 5 ) , The s a l i n i t y p r o f i l e s

t h a t a p p e a r t o r u n p a r a l l e l t o t h e e s t u a f i n e a x i s ( F i g u r e 7 c ) a r e t h e r e s u l t of

s t r o n g e a s t e r l y winds d u r i n g t h a t measurement p e r i o d ( F i g u r e 6 ) . T h i s i l l u s t r a t e s

t h e f o r c e of winds i n t h e Pamlico R i v e r E s t u a r y on w a t e r movements r a t h e r t h a n

t i d a l f o r c e s ,

The p l a n k t o n bay s y s t e m of Pamlico Sound r e p l a c e s much of o l i g o h a l i n e system

of t h e Pamlico R i v e r E s t u a r y d u r i n g t h e l a t e summer and f a l l , However, d u r i n g t h e

more p r o d u c t i v e time of t h e y e a r t h e system i s e s s e n t i a l l y o l i g o h a l i n e , p a r t i c u l a r l y

i n t h e s h a l l o w waters where most of t h e s p e c i e s e x i s t . The more o r l e s s permanent

o l i g o h a l i n e system l i e s westward of I n d i a n I s l a n d ( F i g u r e 2).

During t i m e s of a p p r e c i a b l e f r e s h w a t e r f l o w i n t h e Pamlico R i v e r E s t u a r y

s a l i n i t y s t r a t i f i c a t i o n c a n b e o b s e r v e d . T h i s s t r a t i f i c a t i o n , however, can b e

r a p i d l y b r o k e n yp by s t r o n g winds,

111. A . 3 . Temperature

I n c o n t r a s t t o t h e l a r g e changes i n s a l i n i t y , t h e t e m p e r a t u r e changes were

s l i g h t t h r o u g h o u t t h e e s t u a r y ( 1 0 ) . T y p i c a l l y , t h e r i v e r was warmer t h a n t h e e s t u a r y

d u r i n g t h e s p r i n g when t h e r i v e r w a t e r s warm up f a s t e r , I n t h e f a l l , t h e r e i s a

r e v e r s a l of t h i s s i t u a t i o n a s t h e sound w a t e r s c o o l s l o w e r t h a n t h e r i v e r w a t e r s

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PAMLICO RIVER SALINITY (%,)

JULY 13, 1967

F i g u r e 7 . S u r f a c e p r o f i l e s ( i n p p t ) i n t h e P a m l i c o R i v e r E s t u a r y . a . 29 J a n u a r y 1968

(33)

The maxinum t e m p e r a t u r e of 1967 (31,Z C, 8 8 , 2 F) was r e c o r d e d on 23 August b u t

t h e l o w e s t t e m p e r a t u r e r e c o r d e d on t h a t same d a t e was 24.5 C ( 7 6 . 1 F ) . Both of

t h e s e e x t r e m e s were a l o n g t h e s h o r e and i l l u s t r a t e s j u s t how d i f f i c u l t i t i s t o

d e t e r m i n e t h e a v e r a g e t e m p e r a t u r e of t h i s e s t u a r y . F o l l o w i n g t h i s d a t e , t h e

e s t u a r y began t o c o o l and t h e warmer w a t e r of t h e sound o c c a s i o n a l l y i n t r u d e d .

F i n a l l y , t h e e n t i r e e s t u a r y was v i r t u a l l y i s o t h e r m a l a t 3 . 5 t o 3.7 C ( 3 8 . 3 t o 38.5 F )

d u r i n g w i n t e r ,

The summer of 1968 was q u i t e warm and s u r f a c e t e m p e r a t u r e s reached 34 C on

6 August. A t e m p e r a t u r e of 36 C (96.8

F)

was found a t t h e bottom of S t a t i o n H4

on 23 August. T h e r e was s t a t i f i c a t i o n of t h e s a l i n i t y a t t h i s s t a t i o n a l s o , and

s o t h i s i s l i k e l y a pocket of warm, s a l i n e w a t e r t h a t i s h e a t e d by t h e s u n l i g h t .

T h i s r e s e m b l e s t h e g r e e n h o u s e e f f e c t of a t m o s p h e r i c h e a t i n g and h a s been found i n

many a q u a t i c s i t u a t i o n s . Minimum t e m p e r a t u r e s were reached i n J a n u a r y , followed

by a r a p i d r i s e i n t e m p e r a t u r e d u r i n g F e b r u a r y .

111, A ,

4,

D i s s o l v e d Oxygen

D i s s o l v e d oxygen c o n c e n t r a t i o n s i n t h e e s t u a r y a r e a b a l a n c e between t h e

p r o c e s s of e q u i l i b r i u m of oxygen w i t h t h e a i r , t h e p h o t o s y n t h e s i s and t h e

r e s p i r a t i o n . Some g e n e r a l p a t t e r n s f o r s u r f a c e and bottom d i s s o l v e d oxygen

c o n c e n t r a t i o n s i n t h e Pamlico R i v e r E s t u a r y a r e g i v e n i n F i g u r e 8 . While s a t u r a t i o n

v a l u e s of d i s s o l v e d oxygen e x i s t a t t h e s u r f a c e d u r i n g t h e e n t i r e y e a r , d i s s o l v e d

oxygen d e c r e a s e d t o v e r y low c o n c e n t r a t i o n s d u r i n g t h e summer i n t h e middle of t h e

e s t u a r y ( F i g u r e 8 c ) . Low oxygen c o n c e n t r a t i o n s o c c u r r e d a t t h e two s t a t i o n s (H16

and H17) c l o s e s t t o t h e i n f l o w i n g T a r R i v e r . It i s l i k e l y t h a t t h i s i s caused by

sewage from c i t i e s up r i v e r , e s p e c i a l l y Washington,

N,

C . P e r c e n t s a t u r a t i o n of

d i s s o l v e d oxygen a t t h e s u r f a c e and t h e bottom of t h e Pamlico R i v e r E s t u a r y f o r

sampling s t a t i o n s t h r o u g h o u t i t s l e n g t h d u r i n g a p e r i o d between w i n t e r and summer

(34)

PAMLICO RIVER 5 52

T

.-.

~ n n

-.-.

P

JULY 4, 1969

636

0 12

PAMLICO RIVER BOTTOM D.O. JULY 4, 1969

1.61

1.12

F i g u r e 8. D i s s o l v e d oxygen c o n c e n t r a t i o n s ( m l l l i t e r ) i n t h e P a m l i c o R i v e r E s t u a r y . a . s u r f a c e , 26 F e b r u a r y 1969

(35)

T a b l e 2. P e r c e n t S a t u r a t i o n of Dissolved Oxygen a t t h e s u r f a c e (S) and bottom (B) o f t h e Pamlico R i v e r E s t u a r y 1 3 December 1968

-

4 J u l y 1969.

S t a t i o n : H 1 H2 H3 H4 H6 H7 H8 H10 H13 H15 H16 H17

1 3 Dec. 1968 6 J a n . 1968 6 Feb. 1969 26 Feb. 1969

h3

w

1 Apr.. 1969 15 Apr. 1969 2 May 1969 3 J u n e 1969 19 J u n e 1969

100 96 95 98 No Data No Data

98 7 8

95 80

86 93

7 1 100

- -

-

9 1

---

106 9 1 8 5 7 7 76 1 0 1 96

---

---

97 93 105 9 1

(36)

111. A . 5. C o n c l u s i o n s

T h i s s e c t i o n of t h e r e p o r t summarizes s a l i n i t y , t e m p e r a t u r e and d i s s o l v e d

oxygen measurements made i n t h e Pamlico R i v e r E s t u a r y of North C a r o l i n a d u r i n g

1965 t o 1969. The e s t u a r y i s s h a l l o w and n a t u r a l l y p r o d u c t i v e , w i t h a s a l i n i t y

r a n g e of 0.5 t o 15 o r 20 p p t . The l u n a r t i d e i s damped o u t by t h e O u t e r Banks

s o t h a t t h e r e i s o n l y a 6 i n c h change i n w a t e r l e v e l , Wind t i d e s a r e more

i m p o r t a n t and may r a i s e o r lower t h e w a t e r l e v e l more t h a n 3 f t .

Changes i n s a l i n i t y were c l o s e l y r e l a t e d t o t h e amount of i n f l o w i n g f r e s h w a t e r .

T h i s produced changes a t one s t a t i o n , some 10 m i l e s from t h e mouth of t h e e s t u a r y ,

of 13 p p t . Upstream dams on t h e T a r R i v e r would c e r t a i n l y r e d u c e much of t h i s

f l u s h i n g of f r e s h w a t e r and would t h e r e b y change t h e c h a r a c t e r of t h e e s t u a r y . I t

i s recommended t h a t s t u d i e s be made of t h e e f f e c t of t h e s e changes on t h e a n i m a l s

and p l a n t s of t h e e s t u a r y s o t h a t a c c u r a t e p r e d i c t i o n s c a n b e made.

T h e r e were a l s o changes i n t h e s a l i n i t y d i s t r i b u t i o n due t o t h e wind

speed and d i r e c t i o n and a l s o t o t h e C o r i o l i s F o r c e . I n g e n e r a l , t h e e s t u a r y

had lower s a l i n i t i e s a l o n g t h e s o u t h s h o r e a s a r e s u l t of t h e s e f a c t o r s .

Temperatures ranged from c l o s e t o f r e e z i n g up t o 93 F , a l t h o u g h t e m p e r a t u r e s

above 8 9 F were u n u s u a l . T h e r e a r e no i n d u s t r i a l e f f l u e n t s a d d i n g h e a t s o

t h e t e m p e r a t u r e s found were t h e n a t u r a l c o n d i t i o n of t h e e s t u a r y . I t i s a l s o

i m p o r t a n t t o n o t e t h a t t h e t e m p e r a t u r e v a r i e d by a s much a s 7 F w i t h i n t h e

e s t u a r y on one d a t e s o t h a t a v e r a g e t e m p e r a t u r e s o r n a t u r a l c o n d i t i o n s of t h e

w a t e r a r e e x t r e m e l y d i f f i c u l t t o d e f i n e . These f a c t s become i m p o r t a n t when s t a n d a r d s

a r e b e i n g s e t f o r t h e r m a l a d d i t i o n s t o e s t u a r i e s , I t i s recommended t h a t 93 F would

b e a l o g i c a l upper l i m i t f o r a n a b s o l u t e s t a n d a r d f o r t h i s e s t u a r y i n s t e a d of t h e

90 F F e d e r a l S t a n d a r d ,

The e s t u a r y s t r a t i f i e s i r r e g u l a r l y , b u t t h e w a t e r s a r e s o r i c h t h a t t h e

bottom w a t e r s l o s e a l l t h e i r d i s s o l v e d oxygen w i t h i n a week o r s o a f t e r s t r a t i f i -

Figure

Figure 2: Pamlico River Estuary, showing s e r i e s  of s t a t i o n s  f o r  e a r l y  s t u d i e s  of phosphorus e f f e c t s  ( l e t t e r )  and hydrographic samples (numbers)

Figure 2:

Pamlico River Estuary, showing s e r i e s of s t a t i o n s f o r e a r l y s t u d i e s of phosphorus e f f e c t s ( l e t t e r ) and hydrographic samples (numbers) p.18
Figure 3: Diagram of estuary, showing s t a t i o n s  f o r  Mar 1967-Feb 1968.

Figure 3:

Diagram of estuary, showing s t a t i o n s f o r Mar 1967-Feb 1968. p.20
Figure 5: Water flow (cubic f e e t  per second) i n  t h e  Tar River a t  Tarboro, N

Figure 5:

Water flow (cubic f e e t per second) i n t h e Tar River a t Tarboro, N p.26
Figure 6: Wind speed and d i r e c t i o n  a t  t h e  Texas Gulf S u l f u r  Company near Aurora, N.C

Figure 6:

Wind speed and d i r e c t i o n a t t h e Texas Gulf S u l f u r Company near Aurora, N.C p.27
Table 1, Zxchange r a t i o s  and h a l f - l i f e  values estimated f o r  volume segments within section5 of the Pamlico River Estuary when freshwater inflow averaged

Table 1,

Zxchange r a t i o s and h a l f - l i f e values estimated f o r volume segments within section5 of the Pamlico River Estuary when freshwater inflow averaged p.28
Figure 6: Wind speed and d i r e c t i o n  a t  t h e  Texas Gulf S u l f u r  Company near Aurora, N.C

Figure 6:

Wind speed and d i r e c t i o n a t t h e Texas Gulf S u l f u r Company near Aurora, N.C p.29
Table 1, Exchange r a t i o s  and h a l f - l i f e  values estimated f o r  volume segments within section3 04 the Pamlico River Estuary when freshwater inflow averaged

Table 1,

Exchange r a t i o s and h a l f - l i f e values estimated f o r volume segments within section3 04 the Pamlico River Estuary when freshwater inflow averaged p.30
Figure 7 .

Figure 7 .

p.32
Table 2. Percent Saturation of Dissolved Oxygen a t  the surface (S) and bottom (B) of the Pamlico River Estuary 13 December 1968 - 4 July 1969

Table 2.

Percent Saturation of Dissolved Oxygen a t the surface (S) and bottom (B) of the Pamlico River Estuary 13 December 1968 - 4 July 1969 p.35
Table 3, Some samples from 1965 data of the concentration of reactive phosphorus (ug-at  liter) i n  the Pamlico River (See Figure 2 f o r  location of s t a t i o n s ) ,

Table 3,

Some samples from 1965 data of the concentration of reactive phosphorus (ug-at liter) i n the Pamlico River (See Figure 2 f o r location of s t a t i o n s ) , p.39
Figure 9; The means and ranges f o r  t h e  t o t a l  u n f i l t e r e d  phosphorus (ug-at i n  t h r e e  s t r a t a  of t h e  Pamlico River, 1967-1969

Figure 9;

The means and ranges f o r t h e t o t a l u n f i l t e r e d phosphorus (ug-at i n t h r e e s t r a t a of t h e Pamlico River, 1967-1969 p.41
Figure 10. Average biomass and numbers of phytoplankton i n  t h e  Pamlico River Jstuary

Figure 10.

Average biomass and numbers of phytoplankton i n t h e Pamlico River Jstuary p.50
Figure 11. Flow diagram of the experimental arrangement for studying phosphorus exchange with the sediments (5)

Figure 11.

Flow diagram of the experimental arrangement for studying phosphorus exchange with the sediments (5) p.54
Figure 12. Phosphorus concentrations resulting from the release of K2HP0 to the input reservoir and estimated as mean differences in dissolve2 reactive

Figure 12.

Phosphorus concentrations resulting from the release of K2HP0 to the input reservoir and estimated as mean differences in dissolve2 reactive p.56
Table 5 (continued).

Table 5

(continued). p.59
Table 6. Student's t values calculated for net mass transports of four phosphorus types (D=dissolved, R=reactive, P=particulate, U=unreactive) by sand and

Table 6.

Student's t values calculated for net mass transports of four phosphorus types (D=dissolved, R=reactive, P=particulate, U=unreactive) by sand and p.60
Table 8. Mean meat weight-shell r a t i o  of Rangia cuneata f o r  sediment types and phospho- r u s  concentrations (Tenore 1967)

Table 8.

Mean meat weight-shell r a t i o of Rangia cuneata f o r sediment types and phospho- r u s concentrations (Tenore 1967) p.62
Figure 14. 3 Carbon-14 uptake (mg ~ / m  / h r )  under c o n t r o l l e d  l i g h t  and temperature c o n d i t i o n s  f o r  samples from t h e  Pamlico River on

Figure 14.

3 Carbon-14 uptake (mg ~ / m / h r ) under c o n t r o l l e d l i g h t and temperature c o n d i t i o n s f o r samples from t h e Pamlico River on p.74
Figure 16. 3 Carbon-14 uptake (mg ~ / m  / h r )  under c o n t r o l l e d  l i g h t  and temperature conditions f o r  samples from t h e  Pamlico River on 29 J u l y  1967

Figure 16.

3 Carbon-14 uptake (mg ~ / m / h r ) under c o n t r o l l e d l i g h t and temperature conditions f o r samples from t h e Pamlico River on 29 J u l y 1967 p.75
Figure 15. Biomass (wet weight) of phytoplankton i n  t h e  Pamlico River on 31 J u l y  1967

Figure 15.

Biomass (wet weight) of phytoplankton i n t h e Pamlico River on 31 J u l y 1967 p.75
Table 14, Phytoplanktonic primary productivity (in situ) in mgfm /day, and analysis 2

Table 14,

Phytoplanktonic primary productivity (in situ) in mgfm /day, and analysis 2 p.77
Table 15, Phytoplankton biomass i n  m g l l i t e r ,  and analysis of variance from slime waste additions t o  experimental estuaries (Carpenter 1969)

Table 15,

Phytoplankton biomass i n m g l l i t e r , and analysis of variance from slime waste additions t o experimental estuaries (Carpenter 1969) p.78
Table 16. Cell numbers x 10 / l i t e r  of Anabaena 3 s p .  and Spirulina sp. i n  t h e  a r t i f i c i a l  e s t u a r i e s ,  with an analysis of varia'nce and 1sd test among

Table 16.

Cell numbers x 10 / l i t e r of Anabaena 3 s p . and Spirulina sp. i n t h e a r t i f i c i a l e s t u a r i e s , with an analysis of varia'nce and 1sd test among p.80
Table 17. Algal primary productivity ( i n  s i t u )  i n  mg ~ / m  L /day i n  the p l a s t i c  pools with an analysis of variance of treatments and a 2

Table 17.

Algal primary productivity ( i n s i t u ) i n mg ~ / m L /day i n the p l a s t i c pools with an analysis of variance of treatments and a 2 p.82
Table 18, 5 Cell numbers x 10 / l i t e r  of Anabaena torulosa i n  the p l a s t i c  pools with a n  analysis of variance of treatments and a 2 x 2 f a c t o r i a l  analysis of variance of main e f f e c t s  and interaction (Carpenter 1969),

Table 18,

5 Cell numbers x 10 / l i t e r of Anabaena torulosa i n the p l a s t i c pools with a n analysis of variance of treatments and a 2 x 2 f a c t o r i a l analysis of variance of main e f f e c t s and interaction (Carpenter 1969), p.83
Table 19, Phytoplankton biomass in mg/liter in the plastic pools with an analysis of variance of treatments and a 2 x 2 factorial analysis of variance

Table 19,

Phytoplankton biomass in mg/liter in the plastic pools with an analysis of variance of treatments and a 2 x 2 factorial analysis of variance p.84
Table 20. -3 Phosphorus uptake i n  ug-at P x 10 / h r / l i t e r  by microorganisms i n  t h e  p l a s t i c  pools with an analysis of variance of treatments, and a 2 x 2 f a c t o r i a l  analysis of variance of main e f f e c t s  and interaction,

Table 20. -

3 Phosphorus uptake i n ug-at P x 10 / h r / l i t e r by microorganisms i n t h e p l a s t i c pools with an analysis of variance of treatments, and a 2 x 2 f a c t o r i a l analysis of variance of main e f f e c t s and interaction, p.86
Figure 17. The e f f e c t  of the additions of NO3 and PO4 plus NO carbon-14. 3 Samples were taken from the slimes p i t

Figure 17.

The e f f e c t of the additions of NO3 and PO4 plus NO carbon-14. 3 Samples were taken from the slimes p i t p.87

References