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MARINE ECOLOGY PROGRESS SERIES
_ .
M ar. Ecol. Prog. Ser.
o, .
Vol. 119: 311-314, 199o
„
P ublished M arch 23
!
Total sample area and estimates of species richness
in exposed sandy beaches
Eduardo Jaramillo1, Anton McLachlan2, Jenifer Dugan3
'Instituto de Zoología, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
2Zoology Department, University oí Port Elizabeth, PO Box 1600, Port Elizabeth 6000, South Africa
3Marine Science Institute, University oí California, Santa Barbara, California 93106, USA
ABSTRACT: Recent studies have show n th at m acroinfaunal
species richness of exposed sandy b eaches increases from
reflective to dissipative conditions. To analyse if this tren d is
affected by sam pling strategies (primarily area sam pled), we
com pared results from surveys carried out in different b each
types of South Africa, A ustralia and Chile. Total area sam pled
in those surveys w as 4.5 m 2. The p ercen tag e of species p re ­
dicted for each beach increased in relation to an in crease in
total sam pling area. Only at a total sam ple area of 4 m 2 w ere
most (>95%) of the species p resen t collected. Sam pling areas
of 1 m 2 and 2 m 2 result in av erag e underestim ations of nearly
40% and 20% of the species, respectively. Beaches h a rb o u r­
ing the highest num ber of species (the most dissipative ones)
need to be sam pled m ore extensively to collect most of the
species, as com pared with b eaches having low er species rich­
ness. A bibliographic survey show ed th a t most of th e studies
carried out on sandy beaches have b een b ased upon sam pling
areas considerably sm aller th an 4 to 4.5 m 2, suggesting that in
m any of the studies the sandy beach m acrofauna was undersam pieu.
dynam ic beach types w ere com pared using data from
m acroinfaunal surveys of exposed sandy beaches on
the coasts of south-central Chile, southeastern South
Africa, and southern and n ortheastern A ustralia
(Table 1). The beach state index calculated for each
site shows that the beaches exam ined spanned a w ide
range of m orphodynam ic beach types. T hree replicate
sam ples of sedim ents (each 0.1 m 2 in area and 25 cm
deep) w ere collected at 15 equally spaced levels along
a transect extending from above the drift line to the
low er lhnit of the sw ash zone (the across-shore strat­
egy). Total area sam pled w as 4.5 m 2. The sedim ent was
sieved through 1 mm m esh and the collected anim als
stored in 5 % form alin until sorting. A program based
on probability theory (H artnoil 1983) w as used to con­
struct species-area curves for sam ple areas up to 5 m 2
KEY WORDS:
relationships
Table 1. Beach characteristics for the sandy b eaches studied
at each geographic area. BSI: b each state index in w hich
values <0.5 are for reflective beaches, 0.5 to 1.0 are for in ter­
m ediate beaches, 1.0 to 1.5 for dissipative beaches and 1.5 to
2.0 for fully dissipative beaches (M cLachlan et al. 1993). The
C hilean b eaches w ere sam pled in S eptem ber 1993, th e South
African one in July 1993 an d those of A ustralia in July 1992
Sandy beach m acroinfauna • Species-area
Studies carried out on sandy beaches of the n o rth ­
w est of USA, South Africa, A ustralia and south-central
Chile (McLachlan 1990, Jaram illo & M cLachlan 1993,
M cLachlan et al. 1993) have show n th at b eaches of
different m orphodynam ic types h arbour differences
in m acrofaunal com munity attributes including species
richness, ab u ndance and biomass. Species richness
increases linearly from reflective to dissipative condi­
tions (e.g. M cLachlan et al. 1993). A lthough changes in
beach type ap p ear to result in p redictable changes in
m acrofaunal species richness, it is also possible that
the above general trends m ay be affected by sam pling
strategies, prim arily area sam pled.
Materials and methods. To exam ine the possibility
that estim ates of species richness m ay be affected by
sam pling strategy (specifically, the area sam pled),
species-area relationships from a ran g e of m orpho­
© Inter-R esearch 1995
Resale o f full article not p erm itted
Site
Area
Chile
Los Molinos Temperate
Mehuin
Temperate
South Africa
King Beach Warm
temperate
Australia
Coorong
Goolwa
McKay
Grasstree
Sarina
Cassuarina
Temperate
Temperate
Tropical
Tropical
Tropical
Tropical
BSI
Type of beach
0.50
1.50
Reflective, microtidal
Dissipative, microtidal
0.95
Intermediate, microtidal
1.03
1.28
1.42
1.52
1.43
1.79
Dissipative, microtidal
Dissipative, microtidal
Ultradissipative, macrotidal
Ultradissipative, macrotidal
Ultradissipative, macrotidal
Ultradissipative, macrotidal
for each beach. A second sam pling strategy (the along­
shore strategy) was used on 2 beaches studied in Chile.
Five sam ples of sedim ent (0.03 m 2 each) w ere collected
at 5 equally spaced levels along 30 transects (1 m
apart) extending from above the drift line to the low er
limit of the sw ash zone. Since the five 0.03 m2 sam ples
of each of the 30 transects w ere pooled (0.15 m 2 for
each transect), the total area sam pled u n d er both
strategies was 4.5 m 2. The 2 sam pling strategies used
in Chile allow ed analysis of the effect of num ber of
b each levels sam pled on estim ates of species richness.
Results. Table 2 shows the results for the acrossshore strategy. The p ercen tag e of species predicted for
each beach increased in relation to an increase in total
sam pling area. The n um ber of species at 5 m 2 sam pling
area was arbitrarily tak en to be 100 %, recognizing that
the curves never flatten out com pletely and thus never
reach 100% in absolute term s. Only at a total sam ple
area of 4 m 2 w ere most (>95% ) of th e species p resen t
collected. Sam pling areas of 1 m 2 an d 2 m 2 resulted in
average underestim ations of nearly 40 and 20% of the
species, respectively (Table 2). The curves w hich re p ­
resen t the situation for each b each (15 beach levels
sam pled) are show n in Fig. 1. The highest species rich­
ness w as found tow ards m ore dissipative conditions
(cf. Fig. 1 and Table 1). B eaches h arbouring the h ig h ­
est nu m b er of species (C assuarina and Serina in A us­
tralia) n eed to be sam pled m ore extensively to collect
m ost of the species, as com pared w ith beaches having
low er species richness (Fig. 1). As n u m b er of species
p resen t increases, total sam pling area needs to be
Fig. 2 shows the results of the com parison of sam ­
pling strategies for the C hilean beaches. N um ber of
Table 2. Total num ber of species reco rd ed as a function of
sam pling area on sandy beaches: total nu m b er of species col­
lected (n) and predicted p e rcen tag e of species w ith increase
in sam pling area
Sites
n
1 m2
2 m2
3 m2
4 m2
5 m2
Chile
Los Molinos
M ehuin
6
9
76.8
73.7
90.3
86.3
96.0
93.2
98.8
97.7
100
100
South Africa
King Beach
11
48.5
72.9
86.7
95.4
100
Australia
Coorong
Goolwa
McKay
G rasstree
Serina
C assuarina
11
13
13
19
20
28
61.4
56.9
60.8
49.4
64.0
63.1
78.3
77.3
79.7
70.7
81.2
81.5
89.0
89.0
90.2
84.9
90.7
91.3
96.8
96.7
96.9
95.6
96.9
97.2
100
100
100
100
100
100
Average %:
61.6
79.8
90.1
96.9
100
C asuarina
2824S e rin a
20•
G rasstree
16McKav
Coorong
Mehuin
"O
a>
Los Molinos
King Beach
4-
2
3
5
4
Fig. 1. P redicted n u m b er of species in relation to an increase
in sam pling area (15 levels sam pled at each beach)
Mehui n
Q.
-Q
8
-
6
-
Los M o lin o s
2-
2
3
4
5
acro ss-shore s t r a t e g y
a lo n g -s h o re s t r a t e g y
Fig. 2. P redicted n u m b er of species in relation to an increase
in sam pling a rea w ith the 2 sam pling strategies used on the
2 b eaches studied in Chile (see text)
beach levels sam pled does not affect the estim ates of
species richness, since both strategies p ro duced a sim ­
ilar trend; i.e. a larg er area of the dissipative beach of
M ehuin needs to be sam pled to collect m ost of the
species, as com pared w ith the reflective beach of Los
Molinos w hich h ad a low er species richness.
Jaram illo et al.: Species richness m exposed sandy beach es
D iscussion. The overall results of these analyses
have profound im plications for sandy b each ecology
and biodiversity of sandy b each m acrofauna. M ost of
the surveys carried out on sandy b eaches have b een
b ased upon sam pling areas considerably sm aller than
4.5 m 2. This assertion is b ased upon a survey we car­
ried out about sam pling m ethodologies rep o rted in 31
p ublished studies from w hich clear inform ation on
sam pling areas could be collected (Table 3). We do not
claim that this survey is a com plete one; how ever, it
clearly shows th at in m any of th e studies the sandy
b each m acrofauna was undersam pled; i.e. the areas
sam pled w ere <1 m 2. Only in 2 of these studies, the
authors sam pled a total area of 4 to 4.5 m 2 (or more)
(Bally 1983, Donn & Cockcroft 1989), the area that our
analysis dem onstrated as necessary to obtain >95%
of the m acrofaunal species living on exposed sandy
beaches of a variety of m orphodynam ic types. In 4 of
the studies, the authors sam pled as m uch as 4 m 2 (or
more), but only in 1 or some of the studied sites (Gauld
Table 3. Total area sam pled (m2) in sandy beach surveys
around the world. R anges are given w hen different total areas
w ere sam pled in the sam e study
Source
G auld & B uchanan (1956)
Wood (1968)
Seed & Lowry (1973)
D exter (1974)
Location
G hana
N ew Z ealand
Ireland
Costa Rica,
Colombia
C roker et al. (1975)
USA
D auer & Simon (1975j
USA
D exter (1976)
Mexico
C roker (1977)
USA
M cLachlan (1977)
South Africa
Jaram illo (1978)
Chile
D exter (1979)
P anam a
W ooldridge et al. (1981)
South Africa
Koop & Griffiths (1982)
South Africa
! Sánchez et al. (1982)
Chile
Bally (1983)
South Africa
Knott et al. (1983)
USA
D exter (1984)
Australia
W endt & M cLachlan (1985)
South Africa
Ismail (1986)
Red Sea
D exter (1986/1987)
Israel, Egypt
Jaram illo (1987)
Chile
Jaram illo et al. (1987)
USA
C larke & Peña (1988)
Chile
D exter (1989)
Egypt
Donn & Cockcroft (1989)
N am ibia
D exter (1990)
Portugal
USA
Larsen & D oggett (1990)
Jaram illo & González (1991)
Chile
Perez E drosa & Junoy (1991) Spain
Defeo et al. (1992)
U ruguay
Jaram illo & M cLachlan (1993) Chile
A rea
sam pled
3.50-5.00
2.00
1.88-2.50
1.20-4.80
0.60-0.72
2.40
2.00-4.00
0.60-0.72
3.00
0.90-1.44
3.00
2.00-3.25
2.50
1.70-2.50
4.00
1.35
1.20
2.00-2.50
0.15
0.30-0.40
0.60-1.30
0.48-0.60
0.72
0.64
6.00-8.40
0.16
0.50
0.54-0.60
1.92-2.08
1.65-4.29
1.20
& B uchanan 1956, D exter '1974, 1976, Defeo et al.
1992).
The total area n ee d e d to be sam pled in m acrofauna
surveys ta rg e ted to find out estim ates of species rich­
ness depends on beach type and tide range. The slope
of curves p resen ted in Fig. 1 suggests th a t for m icro­
tidal beaches (Los Molinos, M ehuin, King Beach,
Coorong, Goolwa) a sam ple area of 3 to 4 m 2 reaches
the point w here the curves start flattening. However,
for the m acrotidal beaches g re ater sam pling effort is
required, probably at least 5 m 2.
A ckn o w led g em ents. T he w ork in Chile w as m ade possible by
financial support from CONICYT (Chile) th rough FONDECYT research project 92/191 and U niversidad A ustral de
Chile (DID project S92/36) to E.J.; th at in A ustralia and South
Africa w as su pported by South Africa FRD Core G rant to A.M.
We th an k the following p eople who assisted us in the field: in
Chile, Pedro Quijón, M arcia G onzález, Jacq u elin e M uñoz,
M aria Avellanal, H eraldo C ontreras, R obert Brumer, R obert
Stead, and Victor Poblete; in Australia, An de Ruyck; in South
Africa, An de Ruyck, M ariano Lastra, A lexandre Soares,
A ndrew Bentley, Ted Donn, an d David Schoem an. We also
than k 3 anonym ous referees for com m ents on an earlier
manuscript.
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This note was su bm itted to the editor
M anuscript first received: Ju ly 14, 1994
R evised version accepted: D ecem b er 27, 1994