Fosberg and M.- H. Sachet

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ATOLL RESEARCH BULLETIN No. 257

TEN YEARS OF CHANGE O N THE GLOVER'S REEF CAYS by

D. R. Stoddart, F.

R.

Fosberg and M.- H. Sachet

Issued by

THE SMITHSON I A N INSTITUTION Washington, D. C., U.S.A.

April 1982

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L i s t of Figures

Location and submarine topography of G l o v e r ' s Reef. A f t e r Dillon and Vedder (1973).

Topography of G l o v e r ' s Reef. From S t o d d a r t (1962, f i g . 37)

.

Legend t o t h e d e t a i l e d p h y s i c a l and v e g e t a t i o n maps of t h e cays.

Northeast Cay 1961 and 1971: topography.

Northeast Cay 1961 and 1971: v e g e t a t i o n . Long Cay North 1961 and 1971: topography.

Long Cay North 1961 and 1971: v e g e t a t i o n . Long Cay 1961 and 1971: topography.

Long Cay 1961 and 1971: v e g e t a t i o n . Middle Cay 1961 and 1971: topography.

Middle Cay 1961 and 1971: v e g e t a t i o n . Southwest Cay I 1961 and 1971: topography.

Southwest Cay I 1961 and 1971: v e g e t a t i o n . Southwest Cay I1 1961 and 1971: topography.

Southwest Cay I1 1961 and 1971: v e g e t a t i o n .

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L i s t of P l a t e s

N o r t h e a s t Cay: a e r i a l view from t h e e a s t 1962

N o r t h e a s t Cay: s t o r m b l o c k and s h o r e e r o s i o n on t h e e a s t s i d e 1961

Long Cay North: S u r i a n a s c r u b on t h e n o r t h s h o r e 1961 Long Cay North: t h e s o u t h s h o r e i n 1 9 7 1

Long Cay from t h e s o u t h e a s t 1962

Southwest Cay I1 : a e r i a l view from t h e s o u t h e a s t 1962 Long Cay: T o u r n e f o r t i a on t h e n o r t h e a s t s p i t 1961

Long Cay: upper s u r f a c e of t h e windward s h i n g l e r i d g e 1961 Long Cay: sandy i s l a n d s u r f a c e w i t h b a c k s l o p e o f t h e windward s h i n g l e r i d g e 1971

Long Cay: mud h o l e and s t a n d i n g w a t e r a t t h e e a s t e n d , s e e n from t h e windward s h i n g l e r i d g e 1961

Middle Cay: windward s h i n g l e r i d g e w i t h hedge o f T o u r n e f o r t i a 1971

Middle Cay: low lagoon s h o r e w i t h Conocarpus 1971

Middle Cay: R h i z o p h o r a a t t h e e a s t end o f t h e lagoon s h o r e 1971 Southwest Cay I : seaward r u b b l e s h o r e 1971

Southwest Cay I : mangrove p o o l a t t h e s o u t h e r n e n d o f t h e i s l a n d 1 9 6 1

S o u t h w e s t Cay 11: exposed r o o t r o c k ' on t h e r e t r e a t i n g lagoon s h o r e 1971

Southwest Cay I : open mangrove 1961

Southwest Cay 11: beachrock w i t h landward d i p on t h e seaward s h o r e 1961

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TEN YEARS OF CHANGE O N THE GLOVER'S REEF CAYS

by D. R. S t o d d a r t , ' F. R. F'osberg2 and M..-H. s a c h e t 2

I ABSTRACT

S c i e n t i f i c s t u d i e s on t h e a t o l l o f G l o v e r ' s Reef, B e l i z e , s i n c e an i n i t i a l survey i n 1961 a r e reviewed. Comparative maps a r e p r e s e n t e d o f each of t h e s i x i s l a n d s on t h e a t o l l , showing morphology and

v e g e t a t i o n , between t h e 1961 survey and a re-survey i n 1971. Most of t h e i s l a n d s show s h o r e l i n e e r o s i o n and remodelling o f windward s h i n g l e r i d g e s a s a r e s u l t of h u r r i c a n e a c t i v i t y . The recorded t e r r e s t r i a l p l a n t s a r e catalogued f o r each of t h e i s l a n d s , and some e x t i n c t i o n s a r e noted. Species-numbers on t h e cays a r e r e l a t e d t o a r e a , and a r e much h i g h e r t h a n t h o s e f o r o t h e r Caribbean and Gulf o f Mexico c o r a l i s l a n d s , presumably because o f h i g h e r r a i n f a l l .

INTRODUCTION

G l o v e r ' s Reef (16O45'NI 870501W) i s one of t h r e e a t o l l s o f f t h e mainland c o a s t o f B e l i z e ( B r i t i s h H o n d u r a s ) , c e n t r a l America. When v i s i t e d i n 1961 i t was one o f t h e least-known r e e f s i n t h e Caribbean, i n s p i t e of i t s t y p i c a l a t o l l f e a t u r e s . I t was d e l i n e a t e d on c h a r t s

(Admiralty Chart 1797 o f 1929) i n t h e most rudimentary manner, and p u b l i s h e d s c i e n t i f i c l i t e r a t u r e about it was l i m i t e d t o b r i e f r e p o r t s on v i s i t s by t h e o r n i t h o l o g i s t S a l v i n i n 1862, by t h e Pawnee Expedition i n 1925, and by t h e Mandel Caribbean Expedition i n 1940. The account o f t h e a t o l l p u b l i s h e d by S t o d d a r t (1962, pp. 17-30, 83-98) was t h u s n e c e s s a r i l y of a p r e l i m i n a r y n a t u r e .

' ~ e ~ a r t m e n t o f Geography, Cambridge U n i v e r s i t y , England 2 ~ m i t h s o n i a n I n s t i t u t i o n , Washington, D.C., U .S .A.

Manuscript r e c e i v e d January 1981

--

Eds.

IMSWE ( I n v e s t i g a t i o n s o f Marine Shallow Water Ecosystems) C o n t r i b u t i o n No. 75

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Since t h e n , however, t h e r e has been a g r e a t d e a l of s c i e n t i f i c i n v e s t i g a t i o n on Glover' s Reef. The CITRE p r o j e c t (Comparative

I n v e s t i g a t i o n s of Tropical Reef Ecosystems) included t h e a t o l l a s one of i t s p o t e n t i a l study s i t e s , and reconnaissance v i s i t s were made t o i t i n January and June 1971, followed i n November 1971 by a planning workshop f o r 40 s c i e n t i s t s h e l d a t Long Cay (Smith, i n Sachet and Dahl (1974), l i s t s p a r t i c i p a n t s )

.

Descriptions of t h e r e e f s r e s u l t i n g from CITRE s t u d i e s were given by Dahl e t a 1

.

(1974, pp. 55-58)

,

and marine algae and sea-grasses c o l l e c t e d during t h e p r o j e c t were reported by Tsuda and Dawes (1974). In 1972 N. James, R. N. Ginsburg and a s s o c i a t e s c a r r i e d o u t s t u d i e s of the deep r e e f s using t h e deep-diving submersible N e k t o n

HISTORY

The e a r l y h i s t o r y of t h e a t o l l i s obscure, a s indeed i s t h a t of most of the r e e f s i n t h e western Caribbean. I t can p o s s i b l y be

i d e n t i f i e d a s t h e "Ilbob" o r "Ylbob" of maps by Herrera d a t e d 1601-1615 and of De Laet i n 1625, and d e r i v a t i v e c h a r t s (Vindel 1955). I t

appears a s "Longorif" i n t h e P l a n o d e l a C o s t a d e Honduras of 1756; a s

"Arrecife de Guaneros" i n a map by J. J. de C a s t i l l o , dated 1753 (reproduced by Craig 1966, p. 38) ; and a s Glover's Reef by Speer (1771) and A r r e c i f e Largo, Glover's Reef o r Long Reef by J e f f e r y s (1775)

.

S p e e r ' s map marks t h r e e un-named cays; J e f f e r y s ' s map has f i v e un-named cays i n t h e south and "The Two Spots" a t t h e northern end.

The f i r s t Admiralty survey by Fdchard Owen i n 1830 adopts t h e name of Glover's Reef, which then became s t a n d a r d , and a l s o f o r t h e f i r s t time names Northeast, Long, Middle, and Southwest Cays.

The only e v e n t of any s i g n i f i c a n c e i n t h e recorded h i s t o r y of t h e a t o l l i s t h e wreck of t h e schooner S u s a n , Captain Harry Maury, which s a i l e d from Mobile on 4 December 1858 with emigrants and f i l i b u s t e r s bound f o r Omoa, Republic of Honduras, wrecked 10-12 miles from t h e cays on 16 December (Doubleday 1886 ; Scroggs 1916)

.

The v e s s e l was found by a f i s h i n g b o a t which had taken f i s h , green t u r t l e and coconuts t o t h e Belize market, and t h e passengers and crew were taken t o Middle Cay.

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T a b l e 1. V i s i t o r s t o G l o v e r ' s R e e f

D a t e 1 8 5 8 December 1862 May

1 9 2 5 A p r i l 14-20

1 9 4 0 J a n u a r y 18

1969 March

1 9 7 1 J a n u a r y 17-22

J u n e 20-27

November 1-13

1972 1 9 7 3 J u l y

V i s i t o r Susan, C a p t . Maury Mary Ann, 0. S a l v i n Pawnee, H . P. Bingham

Mandel C a r i b b e a n E x p e d i t i o n

D. R. S t o d d a r t S . P. Murray D. M. Devaney J. Weber A. A n t o n i u s

Work

O r n i t h o l o g y Marine f a u n a

Marine m o l l u s c a R e p t i l e s

Geomorphology V e g e t a t i o n E c h i n o d e r m s CITRE s t u d i e s

A. A n t o n i u s , A. D a h l , K . R u e t z l e r

S . V. S m i t h a n d p a r t y o f 4 0

N. P. J a m e s , R. N. G i n s b u r g , Deep r e e f Nekton

P i p p e n

Y . B. L i n h a r t

F l o r a F l o r a

P u b l i c a t i o n Maury 1 8 5 9

S a l v i n 1 8 6 4 ; Coues 186.4 Boone 1 9 2 7 , 1 9 2 8 a - d l B r e d e r 1 9 2 7

Haas 1 9 4 1 ; S c h m i d t 1 9 4 1

S t o d d a r t 1962 Devaney 1974 Dahl e t a1 1974 T s u d a a n d Dawes 1974 T h i s p a p e r

James a n d G i n s b u r g 1 9 8 0

L i n h a r t 1 9 8 0

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This was s a i d t o be an i s l a n d of 30 a c r e s (12 h a ) , with a "continuous grove of cocoa palms

. . .

[and] e n t i r e freedom from underbrush"

(Doubleday 1886, p. 212)

.

Here they l i v e d on "conch' and g r e e n - t u r t l e soup, f i s h i n g r e a t v a r i e t y , cocoa-nuts, yams, p l a n t a i n s , and bread- f r u i t , a l l i n g r e a t abundance", u n t i l rescued by H.M.S. B a s i l i s k , s e n t from B e l i z e , on Christmas Day 1858. There a r e b r i e f accounts o f t h i s i n c i d e n t i n H a r p e r ' s Weekly, 8 January 1859, p. 22, and 15 January 1859, p. 39, and i n t h e Mobile Mercury a t t h e same time [not s e e n ] , b u t t h e most c i r c u m s t a n t i a l account i s c o n t a i n e d i n l e t t e r s by Captain Maury p u b l i s h e d i n The Mobile Daily R e g i s t e r , v o l . 32 (no. 1329)

,

p . 1 f o r 4 January 1859. We a r e g r a t e f u l t o M r M. M. W e i n s t e i n , L i b r a r y o f Congress, f o r c o p i e s of t h e s e documents.

The p r e s e n t s t u d y began with a v i s i t t o G l o v e r ' s Reef by S t o d d a r t and S. P. Murray i n 1961. This was a b r i e f reconnaissance s u p p o r t e d by t h e O f f i c e o f Naval Research and t h e C o a s t a l S t u d i e s I n s t i t u t e o f Louisiana S t a t e U n i v e r s i t y a s p a r t o f a wider s t u d y o f t h e B r i t i s h Honduras c a y s , and we a r e g r a t e f u l t o t h e l a t e P r o f e s s o r Richard J . R u s s e l l and Miss Evelyn P r u i t t f o r making i t p o s s i b l e . The second v i s i t took p l a c e a s p a r t o f t h e CITRE workshop on 1-13 November 1971.

The i s l a n d s were re-mapped and p l a n t s c o l l e c t e d by S t o d d a r t , Fosberg and S a c h e t , and we a r e g r a t e f u l t o D r Stephen V. Smith, P r i n c i p a l I n v e s t i g a t o r , f o r t h e o p p o r t u n i t y t o p a r t i c i p a t e i n t h e CITRE p l a n n i n g s e s s i o n s . We a l s o thank M r M. Young and Mr R. Coe, of t h e Department o f Geography a t Cambridge U n i v e r s i t y , f o r much c a r t o g r a p h i c and

photographic work, and M r M. M. Weinstein, L i b r a r y o f Congress, who o b t a i n e d newspaper r e c o r d s r e l a t i n g t o t h e wreck o f t h e Susan.

STRUCTURE AND FORM

The s t r u c t u r e of t h e e a s t c o a s t o f t h e YucatanPeninsula i s c o n t r o l l e d by a s e r i e s o f northeast-southwest t r e n d i n g f a u l t b l o c k s , a r r a n g e d en echelon on t h e northwestern f l a n k of t h e Cayman Trench.

One o f t h e s e lineaments u n d e r l i e s t h e B e l i z e b a r r i e r r e e f s o u t h of Gladden S p i t , G l o v e r ' s Reef, and Lighthouse Reef; a n o t h e r t h e c e n t r a l b a r r i e r r e e f , T u r n e f f e , and Banco Chinchorro; and a t h i r d t h e mainland

c o a s t n o r t h o f Ambergris Cay. Of t h e s e , t h e f i r s t i s b e s t developed, and i n p l a c e s ( a s on t h e e a s t s i d e o f Lighthouse Reef) h a s a seaward- f a c i n g s c a r p n e a r l y 3000 m h i g h . A t G l o v e r ' s Reef i t s e l f , t h e s e a f l o o r f a l l s s h a r p l y t o o v e r 1000 m on t h e e a s t s i d e o f t h e a t o l l , b u t only t o shallow s a d d l e s of 300-400 m between t h e a t o l l and t h e b a r r i e r r e e f and t h e a t o l l and Lighthouse Reef. Wells d r i l l e d through t h e o f f s h o r e r e e f s have reached metamorphic rocks probably e q u i v a l e n t i n age t o t h e mainland S a n t a Rosa Group (Carboniferous-Early Permian) a t between 777 and 959 m on G l o v e r ' s Reef, and e x t r u s i v e v o l c a n i c s o f

s i m i l a r age a t 1692 m on Turneffe.

The s u r f ace r e e f s , t h e r e f o r e , s t a n d on f a u l t - b l o c k s t r u c t u r e s , a s o r i g i n a l l y i n f e r r e d from topography and f u l l y confirmed by s e i s m i c i n v e s t i g a t i o n s ( D i l l o n and Vedder 1972, 1973; Uchupi 1973)

.

^{The deep}

w e l l on G l o v e r ' s Reef showed 260 m o f c a l c a r e o u s s i l t s t o n e o f Late

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Cretaceous age, o v e r l a i n by 560 m o f T e r t i a r y r e e f f a c i e s ; s i m i l a r l y , on T u r n e f f e , 660 m o f s h a l e w i t h limestone i s o v e r l a i n by 1030 m o f r e e f f a c i e s ( D i l l o n and Vedder 1973, p. 2721)

.

These sequences

i n d i c a t e r e e f upgrowth on s u b s i d i n g f a u l t b l o c k s a t r a t e s (1-2 cm/1000 y r ) and o v e r time p e r i o d s ( c a 6 0 m i l l i o n y r ) comparable t o t h o s e o f upgrowth on open P a c i f i c s u b s i d i n g volcanoes such a s B i k i n i and Enewetak.

G l o v e r ' s Reef i t s e l f i s a n e l o n g a t e r e c t a n g u l a r a t o l l up t o 32 km long and 12 km wide, w i t h an a r e a o f 260 s q km. I t i s surrounded by a shallow r e e f f l a t , g e n e r a l l y about 450-700 m wide b u t which r e a c h e s 1200 m on t h e e a s t e r n (windward) r e e f s . Living r e e f r e a c h e s t h e s u r f a c e a t t h e o u t e r edge o f t h e r e e f f l a t f o r about 150 m on t h e windward r e e f s . There i s no a l g a l r i d g e d i r e c t l y comparable t o t h o s e o f some I n d o - P a c i f i c a t o l l s , b u t r a t h e r an a l g a l pavement with

There a r e no environmental r e c o r d s from Glover's Reef. The a t o l l i s under t h e i n f l u e n c e o f t h e N o r t h e a s t Trades. There i s a marked

r a i n y season from June t o September, and mean annual r a i n f a l l i s probably about 2500 mm. Mean t i d a l range a t s p r i n g s i s probably about 0.2 m.

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The a t o l l i s f r e q u e n t l y a f f e c t e d by h u r r i c a n e s , a n d r e f e r e n c e t o t h e i r e f f e c t s w i l l b e made i n t h e a c c o u n t s o f t h e c a y s .

There a r e s i x s m a l l i s l a n d s on t h e s o u t h e a s t e r n r e e f o f t h e a t o l l . T h e i r combined a r e a i s a b o u t 32 h a , and i t i s w i t h t h e changing

morphology and v e g e t a t i o n o f t h e s e c a y s t h a t t h i s p a p e r i s concerned.

THE CAYS OF GLOVER'S REEF

There a r e a t p r e s e n t s i x c a y s on G l o v e r ' s Reef, a l l on t h e

s o u t h e a s t s i d e . F i v e of t h e s e ( N o r t h e a s t , Long, Middle, Southwest I and Southwest 11) a r e s i z e a b l e i s l a n d s 360-600 m l o n g ; t h e s i x t h (Long Cay North o r Small Cay) i s an i s l e t 1 6 0 m l o n g n o r t h e a s t o f Long Cay.

I n a d d i t i o n t o t h e main i s l a n d s , J e f f e r y s i n h i s 1775 c h a r t marked

"The Two S p o t s ' ' a t t h e n o r t h end of t h e a t o l l : t h e s e were presumably ephemeral s a n d b o r e s and no l o n g e r e x i s t . Admiralty C h a r t 1797 o f 1929 a l s o marks a f u r t h e r c a y l y i n g w i t h i n t h e l a g o o n on t h e w e s t s i d e o f t h e a t o l l , 7 km from t h e n o r t h w e s t c o r n e r ; i t i s d e s c r i b e d a s h a v i n g t r e e s 6 m t a l l ( W e s t I n d i e s P i l o t , 1956, p p . 459-460). T h i s i s l a n d d i d n o t e x i s t i n 1961, though an ephemeral s a n d b o r e n e a r i t s l o c a t i o n was known a s "Bushy S p o t " o r "Bushy Cay". Owen i n h i s 1830 c h a r t

(Admiralty MS c h a r t H57) a l s o shows no c a y a t t h i s l o c a t i o n . Owen i n 1830 a l s o n o t e d two s m a l l s a n d b o r e s between Middle Cay and Southwest Cays. Each o f t h e e x i s t i n g i s l a n d s was mapped i n 1 9 6 1 and 1971; t h e y a r e d e s c r i b e d from n o r t h t o s o u t h .

N o r t h e a s t Cay (l6O45'N, 87O454'w) F i g u r e s 4-5, P l a t e s 1-2 N o r t h e a s t Cay i s s i t u a t e d a t t h e s o u t h e n d o f t h e unbroken e a s t e r n r e e f o f G l o v e r ' s Reef, on t h e n o r t h s i d e o f t h e e n t r a n c e between it and Long Cay. I t i s s e m i c i r c u l a r i n s h a p e , w i t h maximum dimensions o f 360 x 200 m. I t s s o u t h e r n and s o u t h w e s t e r n s h o r e s , f a c i n g t h e r e e f and t h e c h a n n e l , a r e formed by a s h i n g l e r i d g e w i t h a maximum h e i g h t o f a b o u t 2 m. I n 1961 t h e r e was e v i d e n c e o f r e c e n t s h o r e e r o s i o n on t h e e a s t s i d e o f t h e c a y , i n d i c a t e d by s h o r e c l i f f i n g , s u r f a c e s a n d

s t r i p p i n g , and c o r a l b l o c k s on t h e c a y s u r f a c e ; by 1971 t h e s h i n g l e r i d g e had e x t e n d e d northwards t o c o v e r much o f t h i s a r e a . A s m a l l a r e a o f beachrock on t h e s o u t h s h o r e i n 1961 h a d a l s o i n c r e a s e d i n l e n g t h t o a b o u t 9 0 m i n 1971, and a f u r t h e r s m a l l e x p o s u r e had a p p e a r e d , i n d i c a t i n g s l i g h t r e t r e a t o f t h i s s h o r e . The n o r t h e r n s h o r e i s low and s a n d y , and was s t a b l e d u r i n g 1961-1971. The i n t e r i o r o f t h e i s l a n d i s a l s o low and s a n d y , and t h e r e i s a s m a l l mudhole. The a r e a of t h e i s l a n d was 4.73 h a i n 1961 and 4.48 h a i n 1971. The i s l a n d i s c o v e r e d w i t h coconut woodland, which i s most dense and c o n t a i n s t a l l t r e e s o f B u r s e r a s i m a r u b a , Neea c h o r i o p h y l l a and T h r i n a x r a d i a t a n e a r t h e s o u t h s h o r e . There i s a l u x u r i a n t u n d e r c a r p e t ^'o f W e d e l i a , E u p h o r b i a ,

Ambrosia and g r a s s e s . The most e x t e n s i v e s h r u b on t h e seaward s i d e o f t h e i s l a n d i s T o u r n e f o r t i a g n a p h a l o d e s w i t h s c a t t e r e d Conocarpus

,

Coccoloba and C o r d i a . There w e r e e x t e n s i v e mats o f S e s u v i u m a l o n g t h e l a g o o n s h o r e . F o r f u r t h e r d e t a i l s o f t h e i s l a n d i n 1961 s e e S t o d d a r t

(1962, pp. 87-88, f i g s . 38 and 39)

.

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F o r t y s p e c i e s o f p l a n t s have b e e n r e c o r d e d from t h e i s l a n d ( 2 1 i n 1961, 32 i n 1 9 7 1 , and 32 by L i n h a r t i n 1973)

.

Of t h e s p e c i e s c o l l e c t e d i n 1 9 6 1 t h e o r c h i d B r a s s a v o l a n o d o s a was n o t found i n 1971 o r by L i n h a r t i n 1 9 7 3 , and t h e s i n g l e s h r u b o f S u r i a n a m a r i t i m a o n t h e s o u t h w e s t

s h o r e h a d d i s a p p e a r e d by 1971. I n t h e f o l l o w i n g s p e c i e s l i s t , C d e n o t e s a c o l l e c t i o n and S a s i g h t r e c o r d ; t h e 1 9 7 3 r e c o r d s a r e t h o s e l i s t e d by L i n h a r t (1980, pp. 62-63)

.

S p e c i e s marked w i t h an a s t e r i s k a r e n o t n a t i v e t o t h e B e l i z e cay f l o r a , b u t t h i s d o e s n o t n e c e s s a r i l y i m p l y t h a t t h e y have b e e n d e l i b e r a t e l y i n t r o d u c e d on a l l t h e i s l a n d s on which t h e y o c c u r .

A c r o s t i c h u m a u r e u m 71C 73 * ~ e r m i n a l i a c a t a p p a 71C 73 C e n c h r u s i n c e r t u s 73 B u m e l i a r e t u s a 71C 73

E r a g r o s t i s p r o l i f e r a 61C 71C 73 P o u t e r i a c a m p e c h i a n a 71C 73 E u s t a c h y s p e t r a e a 71C 73

P a s p a l u m d i s t i c h u m 71C 73 P a s p a l u m l a x u m 61C 73 S p o r o b o l u s v i r g i n i c u s 71C S p o r o b o l u s s p . 6 1 s

C y p e r u s l i g u l a r i s 73

C y p e r u s p l a n i f o l i u s 61C 71C 7 3

F i m b r i s t y l i s cymosa 71C 73

" ~ o c o s n u c i f e r a 6 1 s 71s 73 T h r i n a x r a d i a t a 61C 715 73 C r i n u m a m a b i l e 71C

H y m e n o c a l l i s L i t t o r a l i s 71C B r a s s a v o L a n o d o s a 61C

F i c u s s p . 61C 71C 7 3

C o c c o l o b a u v i f e r a 6 1 s 71C 73 Neea c h o r i o p h y l l a 61C 71C 73 S e s u v i u m p o r t u l a c a s t r u m 61C

71C 73

C h r y s o b a l a n u s i c a c o 71C 73 Mucuna s p . 71s

Long Cay N o r t h (16O45'N, 8 7 O 4 6 ' ~ )

C o r d i a s e b e s t e n a 61C 71C 73 T o u r n e f o r t i a g n a p h a l o d e s 6 1 s

71C 73

S t a c h y t a r p h e t a j a m a i c e n s i s 73 P i thecell obi um k e y e n s e 7 3 S u r i a n a m a r i t i m a 6 1 s

B u r s e r a s i m a r u b a 6 1 s 71C 73 E u p h o r b i a b l o d g e t t i i 61C 71C E u p h o r b i a m e s e m b r i a n t h e m i f o l i a

61C 71C 73

E u p h o r b i a s p . 6 1 s 73

P a s s i f l o r a s u b e r o s a 61C 71C 73 C o n o c a r p u s e r e c t u s 61C 71C 73 L a g u n c u l a r i a r a c e m o s a 73

E r i t h a l i s f r u t i c o s a 61C 71C 73 Ernodea l i t t o r a l i s 71C

A m b r o s i a h i s p i d a 61C 71C 73 B o r r i c h i a a r b o r e s c e n s 71C W e d e l i a t r i l o b a t a 61C 71C 73

F i g u r e s 6-7, P l a t e s 3-4 T h i s i s a s m a l l s h i n g l e c a y on a d e t a c h e d r e e f p a t c h i n t h e main c h a n n e l between N o r t h e a s t Cay and Long Cay; i t w a s s o named by

S t o d d a r t (1962, p p . 88-89, f i g . 40)

,

thougb Dahl e t a l . (1974, p . 56) c a l l i t L i t t l e Cay and F o s b e r g e t a 1 . (1981) S m a l l Cay. I n 1 9 6 1 i t w a s m a i n l y composed o f s a n d w i t h some s h i n g l e i n t h e c e n t r a l p a r t and a l o n g

t h e e a s t s h o r e ; i t formed an i s l a n d 145 m l o n g and up t o 48 m w i d e , w i t h a n a r e a o f 0.44 h a . I t w a s p r o b a b l y n o t more t h a n 1 m above s e a -

l e v e l . I t w a s c o v e r e d w i t h a s c r u b o f S u r i a n a m a r i t i m a 3 m t a l l w i t h

~ o r r i c h i a

,

T o u r n e f o r t i a and C o n o c a r p u s and a ground c o v e r o f S e s u v i urn, E u p h o r b i a and g r a s s e s . T h e r e were a few j u v e n i l e c o c o n u t s . By 1 9 7 1

t h e r e had b e e n some e r o s i o n o n t h e s o u t h s h o r e and c o n s i d e r a b l e

a c c r e t i o n on t h e n o r t h , and t h e g r e a t e r p a r t o f t h e i s l a n d w a s formed o f s h i n g l e . The p o s i t i o n o f t h e g r o u p o f c o c o n u t s on the s o u t h s h o r e e n a b l e s t h e r e l a t i v e l o c a t i o n s t o b e p l o t t e d a c c u r a t e l y . The

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v e g e t a t i o n i s s t i l l dominated by S u r i a n a s c r u b , b u t C o n o c a r p u s and T o u r n e f o r t i a have g r e a t l y i n c r e a s e d . There were s e v e r a l more j u v e n i l e coconuts. The l e n g t h o f t h e i s l a n d remained a t 145 m, b u t t h e maximum width had i n c r e a s e d t o 63 m and t h e a r e a o f 0.53 ha.

22 s p e c i e s o f p l a n t s have been recorded from t h e i s l a n d (9 i n 1961, 16 i n 1971 and 19 by L i n h a r t i n 1 9 7 3 ) . S o p h o r a t o m e n t o s a , which

e x i s t e d a s a s i n g l e p l a n t on t h e s o u t h shore i n 1961, had d i s a p p e a r e d by 1971. The s p e c i e s recorded a r e :

Paspalurn d i s t i c h u r n 71C 73 S p o r o b o l u s v i r g i n i c u s 71C 73 C y p e r u s l i g u l a r i s 73

C y p e r u s p l a n i f o l i u s 71C 73 C y p e r u s s p . 61s

*Cocos n u c i f e r a 61s 71s 73 C r i n u m a m a b i l e 71C

H i p p e a s t r u m p u n i c e u m 73 H y m n o c a l l i s l i t t o r a l i s 73

* C a s u a r i n a e q u i s e t i f o l i a 71s 73 C o c c o l o b a u v i f e r a 73

B a t i s m a r i t i m a 73

P h i l o x e r u s v e r m i c u l a r i s 71C

S e s u v i u m p o r t u l a c a s t r u m 6 1 S 7lC 73 S o p h o r a

t o m n

t o s a 6

1s

S u r i a n a m a r i t i m a 61s 71C 73 E u p h o r b i a b l o d g e t t i i 71C

E u p h o r b i a m s e m b r i a n themi f o l i a 71C 73

E u p h o r b i a s p . 61s 73

C o n o c a r p u s e r e c t u s 61s 71C 73 I p o m e a m a c r a n t h a 71C 73 I p o m e a p e s - c a p r a e 71C 73

T o u r n e f o r t i a g n a p h a l o d e s 61s 71C 73 B o r r i c h i a a r b o r e s c e n s 61s 71C 73 Long Cay (16045'N1 87O46'W) F i g u r e s 8-9, P l a t e s 5 , 7, 8 , 9 and 10

Long Cay i s s i t u a t e d a t t h e n o r t h e a s t e r n e x t r e m i t y o f t h e

continuous s o u t h e a s t r e e f of t h e a t o l l . ,When f i r s t mapped i n 1961 i t was 620 m long and v a r i e d i n width from 70 m i n t h e c e n t r e t o 150 m a t each end; i t s e a s t e r n end was prolonged lagoonward by a low sandy

p e n i n s u l a . The a r e a of t h e cay was 6.69 ha. The seaward s i d e o f t h e i s l a n d was formed by a massive double s h i n g l e r i d g e . The o u t e r r i d g e reached up t o 2 m above s e a l e v e l and t h e i n n e r r i d g e 3 m; t h e s h i n g l e complex was 30-40 m along t h e whole seaward s h o r e . The i n n e r r i d g e was formed of o l d e r and c o a r s e r m a t e r i a l , w i t h b l o c k s up t o 0.6 m i n

diameter. There was an a b r u p t j u n c t i o n between t h e i n n e r margin of t h e s h i n g l e and t h e low-lying sandy s u r f a c e o f t h e r e s t of t h e c a y , e s p e c i a l l y a t t h e e a s t e r n end where t h e r e was a d e p r e s s i o n w i t h

s t a n d i n g w a t e r . The n o r t h s h o r e i s low and sandy and f a c e s a shallow bay c a r p e t e d w i t h s e a - g r a s s e s . The morphology o f t h e cay had changed q u i t e c o n s i d e r a b l y by 1971. The seaward s h i n g l e r i d g e had been

reworked, e s p e c i a l l y a t i t s western end where i t had been pushed back o v e r t h e sand s u r f a c e and had become a t r i p l e r i d g e . R e t r e a t o f a few metres had o c c u r r e d along much o f t h e seaward s h o r e , i n c r e a s i n g t h e l e n g t h o f a beachrock r i d g e exposed from 180 t o 360 m. The g r e a t e s t change, however, had taken p l a c e a t t h e e a s t e r n end o f t h e c a y , where t h e s h o r e l i n e had r e t r e a t e d from 15 t o 25 m along i t s e n t i r e l e n g t h . The n o r t h e a s t e r n p e n i n s u l a had a l s o narrowed and moved westwards. A s a r e s u l t t h e t o t a l l e n g t h o f t h e i s l a n d had decreased t o 600 m , and t h e width now v a r i e d from 65-130 m; t h e a r e a i n 1971 was 5.85 h a .

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I n 1961 Long Cay was covered w i t h a coconut p l a n t a t i o n . The i s l a n d was i n h a b i t e d , and t h e ground beneath the coconuts was k e p t c l e a r e d . Most of t h e seaward s h i n g l e r i d g e s were b a r e , except f o r s c a t t e r e d T o u r n e f o r t i a and C o c c o l o b a , and an extensive a r e a a t t h e e a s t e r n end of H y m n o c a l l i s with Conocarpus. The n o r t h e a s t e r n peninsula was covered with a low scrub of S u r i a n a , Conocarpus, T o u r n e f o r t i a and L a g u n c u l a r i a

,

and indeed resembled Long Cay North.

The g e n e r a l a s p e c t of t h e cay was much t h e same i n 1971. The extensive r i d g e - c r e s t a r e a of H y m n o c a l l i s remained,. b u t a l l t h e Coccoloba and T o u r n e f o r t i a of the seaward c o a s t had disappeared. The n o r t h e a s t e r n peninsula was covered with T o u r n e f o r t i a , L a g u n c u l a r i a , Conocarpus and S e s u v i urn.

In 1971 t h e mudhole a r e a was found t o be p a r t l y surrounded by a s u r f a c e outcrop of phosphate rock, previously overlooked. This has a P205 c o n t e n t of 21.7% ( S c o f f i n and S t o d d a r t , i n p r e p . ) . Long Cay i s no longer a b i r d i s l a n d . S a l v i n , who v i s i t e d i t on 1 2 May 1862, found a few t e r n s and some p e l i c a n s (Salvin 1864, p. 384; Coues 1864)

.

^The

date of formation of t h e phosphate rock i s n o t known. The physiographic changes between 1961 and 1971 must be a t t r i b u t e d t o hurricanes.

Possibly much of the c o a s t a l change r e s u l t e d from Hurricane H a t t i e i n 1961. Antonius (1972) was on Long Cay a t t h e time of Hurricane Laura on 20 November 1971. This had winds of 35 m/sec, f o r a time reaching more than 50 m/sec, b u t although some coconut palms were f e l l e d the e f f e c t s were n e g l i g i b l e . Long Cay was occupied by a l o c a l family i n

1961 t o look a f t e r t h e p l a n t a t i o n . By 1971 an American-owned t o u r i s t r e s o r t had opened on the cay, with a s e r i e s of holiday c h a l e t s a t t h e e a s t end. These were damaged i n Hurricane Laura.

28 p l a n t s p e c i e s have been recorded from t h e cay (10 i n 1961, 2 1 i n 1971, and 22 by Linhart i n 1973) ; i n a d d i t i o n t h e r e a r e some

c o l l e c t i o n s made by Pippen i n 1972. One s p e c i e s found i n 1961 (Sophora t o m n t o s a ) has n o t been seen s i n c e . I n a d d i t i o n t o t h e s p e c i e s l i s t e d below, t h e sea-grasses T h a l a s s i a t e s t u d i n u m and S y r i n g o d i urn f i l i f o r m e occur i n shallow water on t h e lagoonward s i d e of the cay. I n t h e following l i s t s p e c i e s marked 72 were c o l l e c t e d by Pippen i n t h a t year.

For f u r t h e r n o t e s on t h i s i s l a n d , s e e Stoddart (1962, pp. 89-91, f i g s . 41, 42 and 44)

.

P s i l o t u r n nudurn 72 A c r o s t i c h u m aureum 7 3 S p a r t i n a p a t e n s 71C

S p o r o b o l u s v i r g i n i c u s 71C 72 7 3

C y p e r u s p l a n i f o l i u s 71C 72 C y p e r u s sp. 61s

F i m b r i s t y l i s cymosa 71C 72 73

* ~ o c o s n u c i f e r a 61s 71s 73 T h r i n a x r a d i a t a 71C 73 H y m e n o c a l l i s l i t t o r a l i s 61s

71C 73

F i c u s sp. 73

Coccoloba u v i f e r a 61s 71C 73 S e s u v i u m p o r t u l a c a s t r u m 71C 73 Mucuna sp. 71C

Sophora tomen t o s a 6

1s

S u r i a n a m a r i t i m a 61s 71C 73 Euphorbia b l o d g e t t i i 73

Euphorbia m e s e m b r i a n t h e m i f o l i a 71C 73

Euphorbia sp. 61s 73 R h i z o p h o r a mangle 73

Conocarpus e r e c t u s 61s 71C 72 73 Burnelia r e t u s a 71C 72 73

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C o r d i a s e b e s t e n a

71C 73

Ageratum l i t t o r a l e

61C 71C 73

T o u r n e f o r t i a g n a p h a l o d e s

61s

Ageratum

(abnormal)

l i t t o r a l e

71C 73 71C

E r i t h a l i s f r u t i c o s a

71C 73

B o r r i c h i a a r b o r e s c e n s

71C 72 73

M e l a n t h e r a n i v e a

71C

Middle Cay (16044'NI 87O48'W) F i g u r e s 10-11, P l a t e s '11-13 Middle Cay i s l o c a t e d n e a r t h e c e n t r e o f t h e unbroken s o u t h e a s t r e e f o f G l o v e r ' s Reef. I t i s a l i g n e d n o r t h e a s t - s o u t h w e s t , p a r a l l e l t o t h e t r e n d o f t h e r e e f . When mapped i n 1961 i t was about 415 m long and up t o 175 m wide, w i t h an a r e a o f 6.03 ha. I n 1971 e r o s i o n a t t h e southwest p o i n t had been c o u n t e r b a l a n c e d by a g g r a d a t i o n a t t h e n o r t h e a s t s p i t , and t h e o v e r a l l dimensions and a r e a (5.97 h a ) remained t h e same.

The seaward s h o r e i s formed by a s h i n g l e r i d g e up t o 35 m wide and 2 m h i g h ; beachrock o u t c r o p s a t t h e f o o t o f t h i s r i d g e , more e x t e n s i v e l y i n 1 9 6 1 t h a n i n 1971. Most o f t h e r e s t o f t h e cay i s low-lying and sandy, w i t h a low leeward s a n d b e a c h , b u t a t t h e s o u t h w e s t e r n e n d t h e r e i s an e x t e n s i v e swamp a r e a w i t h s t a n d i n g w a t e r a b o u t 170 m l o n g and 45 m wide. I n 1961 t h i s was s e p a r a t e d from t h e s e a by a b e l t of t a l l

R h i z o p h o r a ,

b u t by 1971 t h i s had been g r e a t l y reduced and t h e s h o r e showed s i g n s o f e r o s i o n . The s a n d s p i t a t t h e n o r t h e a s t end o f t h e cay had expanded lagoonward d u r i n g t h i s i n t e r v a l and i n c r e a s e d i n s i z e .

Most o f t h e i s l a n d i s covered w i t h coconut woodland. I n 1961 t h e seaward s h i n g l e was - l a r g e l y b a r e , e x c e p t f o r e x t e n s i v e

H y m e n o c a l l i s

and

T o u r n e f o r t i a

a t t h e e a s t e r n end. T h i s had almost completely d i s a p p e a r e d by 1971, b u t

T o u r n e f o r t i a

had c o l o n i s e d a f r e s h a l o n g most o f t h e seaward

s h o r e . There had a l s o been much growth of

L a g u n c u l a r i a , Conocarpus ,

R h i z o p h o r a

and

B o r r i c h i a

a l o n g t h e lagoon s h o r e and on t h e n o r t h e a s t s p i t . There i s a l u x u r i a n t ground cover b e n e a t h t h e coconuts. These were t h e dominant v e g e t a t i o n a s e a r l y a s 1858 when Maury found a

" c o n t i n u o u s grove o f cocoa palms" and " e n t i r e freedom from underbush"

(Doubleday 1886, p . 212). That t h e swampy a r e a was a l s o t h e n i n

e x i s t e n c e i s shown by S a l v i n ' s r e c o r d o f

A c r o s t i c h u m aureum

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E u p h o r b i a mesembri an t h e m i f o l i a 71C 73

E u p h o r b i a s p . 61s 73 H i b i s c u s t i l i a c e u s 61C P a s s i f l o r a s u b e r o s a 71C 73 R h i z o p h o r a m a n g l e 61s 71C 73

C o n o c a r p u s e r e c t u s 61s 71C 73 L a g u n c u l a r i a racemosa 71C 73

* T e r m i n a l i a c a t a p p a 71C B u m e l i a r e t u s a 71C 73

P o u t e r i a campechiana 71C 73 C o r d i a s e b e s t e n a 71C 73

There i s i n a d d i t i o n t h e c a s u a l r e c o r d

T o u r n e f o r t i a g n a p h a l o d e s 61s 71C 73

S t a c h y t a r p h e t a j a m a i c e n s i s 61s 71C 73

D i o d i a s e r r u l a t a 71C

E r i t h a l i s f r u t i c o s a 71C 73 Ernodea l i t t o r a l i s 71C 73 A g e r a t u m li t t o r a l e 71C A g e r a t um m a r i t i m u m 7 3

Ambrosia h i s p i d a 61s 71C 73 B o r r i c h i a a r b o r e s c e n s 61s 71C 73 W e d e l i a t r i l o b a t a 71C 73

i n 1858, a l r e a d y mentioned, of D i o s c o r e a s p .

,

Musa s p . , and A r t o c a r p u s a l t i l i s (Doubleday 1886,

?. 2 1 2 ) .

F o r f u r t h e r d e t a i l s o f Middle Cay, s e e S t o d d a r t (1962, p p . 92-93;

f i g s . 43-45)

.

Southwest Cay I (16O42'N, 87O495'W) F i g u r e s 12-13, P l a t e s 1 4 , 15 and 17 Southwest Cays a r e l o c a t e d a t t h e s o u t h w e s t e x t r e m i t y o f t h e

s o u t h e a s t r e e f o f t h e a t o l l , immediately e a s t o f t h e b r o a d s o u t h e r n s n t r a n c e t o t h e lagoon. Southwest Cay I i s t h e e a s t e r l y o f t h e two.

I t i s a t r a p e z o i d a l i s l a n d w i t h maximum dimensions i n 1961 o f

360 x 270 m. The seaward s h o r e i s formed by a low c a r p e t o f r u b b l e and s h i n g l e r a t h e r t h a n by a d i s t i n c t s h i n g l e r i d g e , a s on t h e o t h e r c a y s , though t h e r e was a s e c t o r o f s h i n g l e r i d g e up t o 2 m h i g h a t t h e s o u t h e r n p o i n t o f t h e cay. T h i s seaward r u b b l e zone i s backed by a zone o f

swamp and s t a n d i n g w a t e r measuring some 230 x 130 m a t t h e e a s t e r n end

~ f t h e i s l a n d , w i t h a second s m a l l e r zone a t t h e w e s t e r n end. Only i n t h e l e e o f t h e s h i n g l e r i d g e i s t h e l a n d s u r f a c e c o n t i n u o u s t o t h e l e e s h o r e . The lagoon s h o r e i s low, sandy, and i n 1961 was u n d e r c u t , w i t h a number o f f a l l e n c o c o n u t s . By 1971 t h e r e were o n l y minor

p h y s i o g r a p h i c changes. There was some rearrangement o f r u b b l e on t h e seaward s i d e , and t h e seaward s h i n g l e r i d g e was much s m a l l e r and e r o d e d . The g r o s s dimensions of t h e i s l a n d remained t h e same, and t h e a r e a was o n l y s l i g h t l y s m a l l e r ( 8 . 7 0 h a compared w i t h 9.02 h a )

.

The v e g e t a t i o n of t h e i s l a n d c o n s i s t s o f coconut woodland and mangroves. The w e s t e r n s h o r e h a s a s t a n d o f t a l l R h i z o p h o r a c l o s i n g t h e e n t r a n c e t o t h e w e s t e r n marsh. R h i z o p h o r a was a l s o found a t t h e e a s t e r n marsh e n t r a n c e , t o g e t h e r w i t h A v i c e n n i a , and t h e r e was a l a r g e clump o f A v i c e n n i a on t h e seaward s h o r e . The l a r g e r marsh was f r i n g e d w i t h C o n o c a r p u s and o t h e r s h r u b s , and many c o c o n u t s had r e c e n t l y been

1,

IPlanted i n i t . Changes by 1971 were r e l a t i v e l y minor. Much o f t h e mangrove a t t h e e n t r a n c e t o t h e l a r g e r marsh had d i s a p p e a r e d , a s had {most o f t h e ~ v i c e n n i a on t h e seaward s h o r e . There had, however, been ' e x t e n s i v e c o l o n i s a t i o n o f t h e s h i n g l e r i d g e by C o r d i a a t t h e s o u t h k o i n t

.

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40 s p e c i e s of p l a n t s a r e recorded from t h e cay, and t h i s t o t a l d o u b t l e s s r e f l e c t s t h e d i v e r s i t y of h a b i t a t on t h e i s l a n d . 16 were recorded i n 1961, 24 i n 1971 and 34 by L i n h a r t i n 1973. Of the s p e c i e s recorded i n 1961 only E u p h o r b i a t r i c h o t o m a has n o t been seen s i n c e , b u t t h i s s u g g e s t s o v e r s i g h t r a t h e r than e x t i n c t i o n . I n p a r t i c u l a r t h e i s l a n d was l e s s thoroughly c o l l e c t e d , except f o r t h e west end, than t h e o t h e r Glover's Reef cays. Species i n t h e following l i s t marked 72 were c o l l e c t e d by Pippen i n 1972. I n t h e following l i s t Ageratum m a r i t i m u m must be considered a dubious r e c o r d , probably a

m i s i d e n t i f i c a t i o n of A. l i t t o r a l e . Andropogon g l o m e r a t u s 7 3 C e n c h r u s i n c e r t u s 71C 73 E r a g r o s t i s p r o l i f e r a 71C 73 E u s t a c h y s p e t r a e a 71C 73 Paspalum d i s t i c h u m 71C 73 Paspalum l a x u m 73

S p a r t i n a p a t e n s 71C S p o r o b o l u s s p

.

^61s

C y p e r u s l i g u l a r i s 73 C y p e r u s p l a n i f o l i u s 73 C y p e r u s sp. 61s

F i m b r i s t y l i s cymosa 73 F i m b r i s t y l i s sp. 61s

"COCOS n u c i f e r a 61s 715 73 H y m e n o c a l l i s l i t t o r a l i s 71s 73 M y r i c a c e r i f e r a 73

C o c c o l o b a u v i f e r a 61s 71s 73 B a t i s m a r i t i m a 71C 73

Iresine d i f f u s a 61C 72 73 P h i l o x e r u s v e r m i c u l a r i s 7 3 P o r t u l a c a o l e r a c e a 71s

S e s u v i u m p o r t u l a c a s t r u m 61s 73 S u r i a n a m a r i t i m a 61s 715 73

Euphorbia b l o d g e t t i i 72

E u p h o r b i a m e s e m b r i a n t h e m i f o l i a 7 3

E u p h o r b i a t r i c h o t o m a 61C E u p h o r b i a s p . 61s 73

P a s s i f l o r a s u b e r o s a 71C 73 R h i z o p h o r a m a n g l e 61s 71s 73 Conocarpus e r e c t u s 61s 71s 73 Laguncul a r i a racemosa 7 1 C Rhabdadenia bi f l o r a 7 3 Ipomoea p e s - c a p r a e 61s 73 C o r d i a s e b e s t e n a 61s 71C 73 T o u r n e f o r t i a g n a p h a l o d e s 61s

71C 73

A v i c e n n i a g e r m i n a n s 61s 71C 73 S t a c h y t a r p h e t a j d m a i c e n s i s

71C 73

C a p r a r i a b i f l o r a 71C 73 E r i t h a l i s f r u t i c o s a 71C 73 Ageratum l i t t o r a l e 71C Ageratum m a r i t i m u m 73

B o r r i c h i a a r b o r e s c e n s 71C 73 E c l i p t a a l b a 73

W e d e l i a t r i l o b a t a 715 73

For f u r t h e r n o t e s on t h i s i s l a n d , s e e S t o d d a r t (1962, pp. 93-95, f i g s . 46-47).

Southwest Cay I1 ( 1 6 ° 4 1 $ ' ~ , 87'50'W) Figures 14-15, P l a t e s 6 , 16 and 1 8 Southwest Cay I1 i s t h e most s o u t h e r l y i s l a n d on G l o v e r ' s Reef.

Although immediately a d j a c e n t t o Southwest Cay I i t i s o f very d i f f e r e n t c h a r a c t e r . I t i s a l i g n e d a t an angle o f 45O t o t h e r e e f edge, and s h i n g l e i s only found along t h e southern shore c l o s e t o t h e r e e f . The r e s t of t h e i s l a n d i s sandy, and t h e r e i s no i n t e r i o r d e p r e s s i o n o r mangrove swamp. When mapped i n 1961 t h e i s l a n d was 560 m long and had a maximum width of 235 m; i t s a r e a was 6.66 ha. The narrow southern s h i n g l e r i d g e reached about 1.5 m above s e a l e v e l . Much o f t h e e a s t e r n shore was low and sandy, with many R h i z o p h o r a s e e d l i n g s , i n s p i t e o f being on t h e seaward s i d e of t h e i s l a n d ; i t faced a broad

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shallow r e e f f l a t connecting with Southwest Cay I. The western shore i s a l s o sandy, b u t narrow and undercut: i n i t s n o r t h e r n p a r t i t was l i n e d with coconut b o l e s and f a l l e n t r u n k s . There were s e v e r a l exposures of r e l i c t beachrock on t h i s western s h o r e , i n d i c a t i n g both beach r e t r e a t and re-alignment a s t h e s h o r e l i n e moved i n a clockwise d i r e c t i o n . There was f u r t h e r evidence of shore e r o s i o n a t t h e southwest p o i n t , though masked i n 1961 by a f r e s h s a n d s p i t . Beach r e t r e a t was likewise e v i d e n t on t h e e a s t s h o r e , a s shown by undercut coconuts and small p a t c h e s of beachrock which unusually showed landward dip. Physiographic changes had been minor by 1971. There had been e r o s i o n round t h e southern p a r t of t h e cay, and t h e southern s h i n g l e r i d g e was more e x t e n s i v e ; t h e r e had a l s o been e r o s i o n a t t h e n o r t h e r n end. A s a r e s u l t t h e o v e r a l l length of t h e cay had decreased t o 540 m and t h e a r e a t o 6.23 ha. The previous beachrock outcrops were s t i l l v i s i b l e , t o g e t h e r with another on t h e south s h o r e .

The i s l a n d i s e n t i r e l y covered with coconut woodland. Except i n t h e southern p a r t t h i s h a s an undergrowth of h e r b s and g r a s s e s . Apart fr.om o c c a s i o n a l C o n o c a r p u s and S u r i a n a bushes t h e only c o a s t a l

v e g e t a t i o n i s a narrow b e l t of R h i z o p h o r a on p a r t of t h e e a s t s h o r e . 40 s p e c i e s of p l a n t s a r e recorded from t h e i s l a n d (12 i n 1961, 37 i n 1971, and 31 by L i n h a r t i n 1 9 7 3 ) , a r e f l e c t i o n of t h e d i v e r s i t y o f t h e ground cover under t h e coconut woodland. They a r e :

Andropogon g l o m e r a t u s 61s 71C C e n c h r u s i n c e r t u s 71C 73 E r a g r o s t i s p r o l i £ e r a 71C E u s t a c h y s p e t r a e a 71C 73 P a s p a l um d i s t i chum 71C P a s p a l u m l a x u m 71C S p a r t i n a p a t e n s 71C S p a r t i n a s p a r t i n a e 73

S p o r o b o l u s

vi

r g i n i c u s 71C 7 3 S p o r o b o l u s s p . 61s

C y p e r u s p l a n i f o l i u s 71C 73 F i m b r i s t y l i s cymosa 71C 73

*Cocos n u c i £ e r a 61s 71s 7 3 H y m e n o c a l l i s l i t t o r a l i s 6 1 S 71C C o c c o l o b a u v i £ e r a 71C

B a t i s m a r i t i m a 73

Iresine

d i f f u s a 71C '7 3 R i v i n a h u m i l i s 71C 73 P o r t u l a c a o l e r a c e a 71C 73 S e s u v i u m p o r t u l a c a s t r u m

61s 71C 73

C a k i l e l a n c e o l a t a 61s 71C

C a n a v a l i a r o s e a 71C 73 S u r i i m a m a r i t i m a 71C 73 E u p h o r b i a b l o d g e t t i i 61C 71C E u p h o r b i a mesembri an t h e m i f o l i a

71C 73

E u p h o r b i a s p . 61s 73

P a s s i f l o r a s u b e r o s a 71C 73 R h i z o p h o r a m a n g l e 61s 71C 73 C o n o c a r p u s e r e c t u s 61s 71C 73 T e r m i n a l i a c a t a p p a 71C

Ipomoea m a c r a n t h a 71C 73 Ipomoea p e s - c a p r a e 71C 73 Ipomoea s t o l o n i f e r a 71C 73 Ipomoea sp. 61s

73 T o u r n e f o r t i a g n a p h a l o d e s 71C 73 S t a c h y t a r p h e t a j a m a i c e n s i s

61C 71C 73

C a p r a r i a b i f l o r a 71C 73 E r i t h a l i s f r u t i c o s a 71C 73 E r n o d e a l i t t o r a l i s 71C 73 Morinda c i t r i f o l i a 71C A g e r a t u m l i t t o r a l e 71C 73 W e d e l i a t r i l o b a t a 71C 73 S a l v i n v i s i t e d t h i s i s l a n d on 12 May 1862. H e found "noddies everywhere

. . .

many thousands i n a l l " , and s p e c u l a t e d "what must t h e numbers have been when t h e Sooty Terns f l o c k e d t o t h e same i s l a n d t '

( S a l v i n 1864, p. 383). Coues (1864) l i s t e d A n o u s s t o l i d u s (on coconuts)

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and Anous t e n u i r o s t r i s (on mangroves)

.

The brown noddies s t i l l i n h a b i t the cay b u t i n small numbers; t h e r e are no records of Sooty Terns

breeding t h e r e . For f u r t h e r d e t a i l s , s e e S t o d d a r t (1962, pp. 95-98, f i g . 4 8 ) .

SUMMARY AND CONCLUS IONS

These surveys have e s t a b l i s h e d t h e v a r i a b i l i t y of r e e f i s l a n d s even over s o s h o r t a p e r i o d a s a decade. A l l of t h e l a r g e r i s l a n d s have decreased i n a r e a (Table 2 )

,

with t h e p o s s i b l e exception of Middle Cay, and t h e s e changes have been mainly e f f e c t e d by e r o s i o n and

remodelling of windward c o a s t s during major storms. Change has been most severe a t the e a s t e r n end of Long Cay, b u t can be t r a c e d on a l l the i s l a n d s i n changed shore morphology, d i s t r i b u t i o n of windward s h i n g l e r i d g e s , and exposure of beachrock. Leeward o r lagoon s h o r e s , on t h e o t h e r hand, have been more s t a b l e , and i n some c a s e s leeward

sand s p i t s have i n c r e a s e d i n a r e a (Long Cay, Middle Cay)

.

The i s l e t of Long Cay North i s t h e only one t o have i n c r e a s e d markedly i n s i z e , b u t it i s so small t h a t t h e change could r e a d i l y be reversed.

Our d a t a do not allow i n f e r e n c e s about c o l o n i s a t i o n of the cays by new p l a n t s p e c i e s between the surveys, nor do we wish t o d i s c u s s t h e f l o r i s t i c biogeography of t h e i s l a n d s i n t h i s paper. We can, however, record t h e following l o c a l e x t i n c t i o n s : B r a s s a v o l a n o d o s a and S u r i a n a m a r i t i m a on Northeast Cay; H i b i s c u s t i l i a c e u s on Middle Cay; and

S o p h o r a t o m e n t o s a on Long Cay and Long Cay North. A l l were represented i n 1961 by s i n g l e specimens. B r a s s a v o l a i s an uncommon epiphyte; t h e H i b i s c u s was a s i n g l e lagoon-shore t r e e ; S o p h o r a i s a beach legume

l i a b l e t o s u b s t r a t e d i s t u r b a n c e . This l a s t e f f e c t i s a l s o seen i n t h e widespread disappearance of T o u r n e f o r t i a and C o c c o l o b a on t h e windward s h i n g l e r i d g e s of Long Cay between 1961 and 1971, a s a r e s u l t of topographic change; they d i d not become l o c a l l y e x t i n c t only because they e x i s t e d i n o t h e r h a b i t a t s on t h e cay.

The t o t a l recorded t e r r e s t r i a l f l o r a of Glover's Reef now stands a t 70 s p e c i e s . Of t h e s e , 3 0 p e r c e n t ( 2 1 s p e c i e s ) occur on only one i s l a n d . Taking t h e s p e c i e s recorded from a l l t h e Belizean a t o l l s

(Lighthouse Reef, Turnef f e , Glover's Reef)

,

28 s p e c i e s o r 40 p e r c e n t of t h e Glover's Reef f l o r a a r e recorded only from t h a t a t o l l : t h i s

undoubtedly r e f l e c t s t h e s t a t e of c o l l e c t i n g on t h e o t h e r a t o l l s r a t h e r than any l o c a l p e c u l i a r i t y on Glover's Reef. There i s a simple

r e l a t i o n s h i p between number of p l a n t s p e c i e s and a r e a of t h e cays, though t h e anomalously low f i g u r e of s p e c i e s f o r Long Cay i n d i c a t e s t h e e f f e c t of coconut p l a n t i n g and c l e a r i n g on t h a t i s l a n d . The s p e c i e s d i v e r s i t y f i g u r e s f o r the Glover's Reef cays a r e markedly higher (by a f a c t o r of two) than those of o t h e r Caribbean and Gulf of Mexico r e e f i s l a n d groups, such a s t h e Dry Tortugas, Alacran, t h e Pedro Cays, and t h e Morant Cays. This probably r e s u l t s from t h e much w e t t e r

environment of Glover' s Reef r a t h e r than from d i f f e r i n g proximity of i s l a n d s t o source a r e a s . The f l o r i s t i c biogeography of western A t l a n t i c reef i s l a n d s w i l l form a s e p a r a t e paper; t h a t of t h e Belize cays i n g e n e r a l has been examined by S t o d d a r t and Fosberg ( i n p r e s s ) .

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T a b l e 2. Chanse on t h e c a v s 1961-1971

I s l a n d Area i n h e c t a r e s P e r c e n t a g e

1961 1 9 7 1 change

N o r t h e a s t 4.73

Long North 0.44

Long 6 -69

Middle 6 .03

Southwest I 9.02 Southwest I1 6.66

T o t a l 33.57

S p e c i e s o f l a n d p l a n t s a c c o r d i n g t o L i n h a r t

(1980)

T o t a l number o f s p e c i e s o f l a n d p l a n t s r e c o r d e d

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