Intertidal and subtidal macroinfauna in the Queule River Estuary, South of Chile
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Revista Chilena de Historia Natural
58:127-137,1985
Intertidal and subtidal macroinfauna in the Queule
River Estuary, South of Chile
Macroinfauna intermareal y submareal en el
Estuario del Rio Queule, Sur de Chile
EDUARDO JARAMILLO, SANDOR MULSOW and RENE NAVARRO
Instituto de Zoologta, Facultad de Ciencias, Universidad Austral de Chile.
Casilla 56 7, Valdivia, Chile
ABSTRACT
An intertidal and subtidal survey of the soft bottom macroinfauna was conducted in the Queule River Estuary (South
of Chile) during January 1981. Samples of 0.0225 m2 were taken from two transects, one located outside the mouth
of the estuary (transect A), the other one in the upper part of the estuary (transect B). The sedimentological analyses
showed sandy bottoms at both transects, with the content of organic matter being higher in transect B. One way
analyses of variance showed that the values of most of the sedimentary parameters (sorting and sand, mud and organic
matter percentages) were not significantly different between the intertidal and subtidal zones of transect A. At transect
B, significant differences were shown for the values of all the parameters, except for the organic matter content. The
ordination of stations by Principal Component Analysis showed results consistent with those obtained by one way
analysis of variance.
A total of 23 and 21 taxa were obtained from transects A and B, respectively. In both, peracarid crustacea were
the most diverse group. At transect A, density and diversity (Shannon-Weaver Index) increased significantly from
intertidal to subtidal levels, but not at transect B. At transect A, low tide level separates an intertidal from a subtidal
assemblage, while in B separate assemblages were not detected. These results are discussed in relation to feeding types
and sedimentological conditions prevalent at both transects. The zonation schemes obtained in this study are compared
with those mentioned for other estuarine or sheltered marine beaches adjacent to the Queule River Estuary.
Key words: transects, sediments, zonation, benthic fauna.
RESUMEN
En enero de 1981 se muestreo Ia macroinfauna intermareal y submareal del Estuario del Rio Queule (Sur de Chile).
Las muestras (0,0225 m 2 ) se obtuvieron en dos transecciones, una localizada al exterior de Ia boca del estuario (transec-
ciyn A), Ia otra en Ia parte superior del mismo (transeccion B). Los analisis granulometricos muestran que am bas ireas
estin constituidas por sedimentos arenosos, siendo mayor el contenido de materia orginica en B. Los resultados de los
aniOisis de varianza de una via muestran que los valores de Ia mayoria de los parimetrRs sedimentologicos (sorteo y
porcentajes de arena, fango y contenido de materia orginica) no fueron significativamente diferentes entre Ia zona in-
termareal y submareal de Ia transeccion A. En B, tales analisis muestran diferencias significativas en los valores de todos
los parimetrRs, con excepcion del contenido de materia orginica. La ordenacion de las estaciones producida por el
Analisis de Componentes Principales muestra resultados consistentes con los obtenidos en los analisis de varianza.
En total se colectaron 23 y 21 taxa respectivamente (transecciones A y B). En ambas transecciones, Peracarida
(Crustacea) fue el grupo mis diverso. En Ia transeccion A Ia densidad y diversidad (lndice de Shannon-Weaver) aumen-
tan significativamente desde Ia zona intermareal a submareal, pero no en B. En Ia transeccion A el nivel de marea baja
separa un conjunto faunistico intermareal de otro submareal, a Ia vez que en B nose detectaron conjuntos separados.
Estos resultados se discuten en relacion a modalidades alimentarias y condiciones sedimentologicas prevalentes en am-
bas transecciones. Los esquemas de zonacion obtenidos en este estudio se comparan con aquellos mencionados para
otras playas estuariales o marinas protegidas adyacentes a! Estuario del Rio Queule.
Palabras claves: transecciones, sedimentos, zonacion, fauna bentonica.
INTRODUCTION Chilean littoral (37-41 S). Studies on the
estuarine geological setting and sedimento-
Until recently, very little was known of logical facies were reported by Pino and
the estuarine soft bottom environment, Mulsow (1983). The intertidal estuarine
representing one of the most typical fea- macroinfauna was studied by Bertran
tures of the central south area of the (1983) in the Lingue River Estuary and
(Recibido el 7 de octubre de 1984. Aceptado el16 de septiembre de 1985 .)128 JARAMILLO ET AL.
by Turner (1984) in the Queule River Es- The Study Area
tuary. More recently, the subtidal macro- The Queule River Estuary is located
infauna has been analyzed by Jaramillo in the south part of Queule Bay (39°24'S,
et al. (1984, in press) and Bravo (1984). 73013'W) (Fig. 1). Transect areas chosen
Bravo (1984) has also described the subtid- for this study were located on the south
al community from shallow waters of side of the estuary. One of them (A) was
Queule Bay, close to the outlet of the located outside the mouth of the estuary,
Queule River Estuary. Until now however, the other (B) in the upper part of the
there has been no attempt to describe estuary (Fig. 1). Unpublished data, indicate
coincidentally a broad or general scheme that the bottom water temperature ranged
of community structure for both the from 1oo to 14.50C in the area adjacent
intertidal and subtidal zones. to transect A, while the values of salinity
This study was planned for the Queule varied between 25.4 and 35.2°/oo (October
River Estuary to find answers to the 1980 to April 1981). No significant diffe-
following main questions: (1) Are there rences were detected between high and
tidal patterns of density and diversity low tides. In the upper part of the estuary,
in different intertidal and subtidal areas the bottom water temperature ranged
of the estuary? (2) Can distinct intertidal from 10.0 to 16.80C at high tide (mean =
and subtidal assemblages be detected? 12.50C) and between 9.4 and 21.ooc
To answer these questions, the intertidal at low tide (mean = 14.6°C). Bottom
and subtidal zones were sampled in two water salinity ranged from 0.1 to 31.6/oo
transects located in areas sufficiently at high tide (mean = 23 .0Å) and between
separated so as to cover the widest possible 0.1 to 18.0Å at low tide (mean = 6.2/oo)
range of environmental conditions. March 1980 to February 1982).
Fig. 1: Queule River Estuary. Location of transects A and B in the area of study.
Estuario del Rio Queule. Ubicaci6n de las transecciones A y Ben el irea de estudio.
MATERIAL AND METHODS 5 em. The same number of replicates was
obtained in the subtidal zone by using an
The intertidal and subtidal macroinfauna Emery grab. A sixth sample for sedimento-
was sampled during January 1981. Stations logical analyses (percentage of gravel,
were ordered on a perpendicular transect sand, mud, organic matter content, mean
in relation to low tide line, 5 meters apart size and sorting) was obtained at each
in the intertidal and 1 meter depth apart station. For mean size and sorting McBri-
in the subtidal zone. de's ( 1971) method of moments was used.
Five replicates of 0.0225 m 2 area were The organic matter content was calculated
obtained at each of the intertidal stations as the loss in weight of dried sediment
using a brass bucket buried to a depth of (60C, 96h) after combustion (550°C,MACROINFAUNA IN A CHILEAN ESTUARY 129
6h). Comparison of sedimentological va- and subtidal zone were carried out with
riables between intertidal (including low the Wilcoxon Test (Wilcoxon U test,
tide level) and subtidal zones at each Sokal & Rohlf 1979). The biocenotic
transect was accomplished by using a similarity between pairs of stations was
one-way analysis of variance (Sokal & calculated with Winer's Index (Saiz 1980).
Rohlf 1979). The values of sedimentologic- The similarity values were used for Cluster
al variables from each station were used Analysis. A dendrogram was obtained
for Principal Component Analysis to group after the Weighed Pair Group Method
samples with similar bottom characteristics. (Sokal & Sneath 1973). The program
For this purpose, the program 4M-BMDP- ACOM, elaborated in Basic Language
79 (University of California Press, Ber- by Navarro ( 1984 ), was used for the di-
keley) was used. versity and similarity indices. The former
Samples for macroinfauna were sieved analyses, beside the Principal Component
(0.5 mm net), preserved with I , buffered Analysis were perfomed on a DECSYS-
formalin, identified and counted. Compa- TEM-2020 computer at the Centro de
risons of the total density per m 2 between Informatica y Computaci6n, Universidad
the intertidal and subtidal zones of each Austral de Chile.
transect were made by using a one-way
analysis of variance. The mean data of RESULTS
specific abundance were used for calcula-
tions of indices of diversity and similarity. The bottom
Diversity was analyzed by using the Shan- The sedimentological analyses indicate that
non-Wearer Index according to Brower sand was the dominant fraction in both
& Zar ( 1977). Comparisons of the mean transects, intertidal and subtidal zones
diversity values between the intertidal (Table I). Mean size values were in the
TABLE 1
Queule River Estuary. Sedimentary parameters from the stations at transects A and B.
1
For the intertidal zone the reference is according to methodology of Emery (1961). ð = -log2
of particle diameter in mm. +low tide level.
Estuario del Rio Queule. Parimetros sedimentologicos en las estaciones de las transecciones A y B.
1 Para Ia zona intermarealla referenda es seg~n metodologia de Emery (1961).
= -log2 del diimetro de Ia particula en mm. + nivel de marea baja.
st. tidal reference mean phi phi of sorting gravel sand mud organic matter
incm
A 1 184 2.13 99.99 1.48
2 146 2.13 99.99
3 2.12 99.99
4 1.95 99.97
5 34 1.88 99.98
+6 1.73 99.98
7 1.73 99.99
8 1.53 99.75
9 1.57 99.93
1.83 99.99 1.89
11 1.95 99.78
B 1 1.33 99.99 3.62
2 62 99.99
3 45 1.68 99.97 4.71
4 25 1.77 99.98 1.91
+5 1.25 99.96 1.64
6 1.98 1.29 85.52 14.44
7 1.77 1.52 91.35 8.11 2.55
8 94.29 5.57 7.71
9 1.73 1.25 92.69 6.49 2.29
1.75 1.31 4.54 89.98 5.48 1.48130 JARAMILLO ET AL.
range of medium sand (1-2 or 250-500 significant differences were detected in
microns), except for some upper intertidal values of mean size, sorting and percentages
levels of transect A and one subtidal level of sand and mud, but not in the organic
from B, corresponding to fine sand (2-3 matter content.
or 125-250 microns) (after Folk 1974 ). In the Principal Component Analysis,
In general, stations of transect A were the first two components accounted
in the range of well sorted (0.35-0.50 ) for (I:60.3; II:20.3) of the total
or moderately well sorted sediments variance in the correlation matrix obtained
(0.50-0.70 while stations of B were for transect A. In component I, percentages
moderately sorted (0.70-1.0 or poorly of sand and mud have the major load,
sorted (1.0-2.0 (after Folk, 1974). while in component II, the organic matter
Only in subtidal levels of transect B (poorly content has the major load. Ordination
sorted) were detected particles larger of stations as projections on the first two
than 2,000 microns, which were represent- components (Fig. 2) shows no clear sepa-
ing broken shells of the barnacle Elminius ration between intertidal and subtidal
kingii, an inhabitant of intertidal and sub- levels. In transect B, the first two compo-
tidal hard bottoms (sandstone) of the nents accounted for (I: 53.2, II:
upper part of the estuary. 28.3) of the total variance. As in transect
One way analysis of variance test indi- A, sand and mud percentages have the ma-
cates that mean size was significantly jor load in component I and the organic
different (P < 0.05) between intertidal matter content in component II. Ordina-
and subtidal zones in transect A, but not tion of stations over these two components
sorting or percentages of sand, mud and (Fig. 3) show a clear gap between intertidal
organic matter content. In transect B, and subtidal levels.
1
11
2 8
2
3
9
4
6
7
5 intertidal stations
subtidal stations
Fig. 2: Queule River Estuary. Principal component ordination of sedimentological samples from transect
A. I. first Principal Component. II. second Principal Component.
Estuario del Rio Queule. Ordenaciyn de las muestras sedimentologicas de Ia transecci6n A, seg~n el aniOisis de Compo-
nentes Principales. 1: primer Componente Principal, II: segundo Componente Principal.MACROINFAUNA IN A CHILEAN ESTUARY 131
®
6
3
. . I
1
7
2
9
5
-
intertidal stations
subtidal stations
Fig. 3: Queule River Estuary. Principal Compo- Estuario del Rio Queule. Ordenaciyn de las muestras
nent ordination of sedimentological samples from sedimentologicas de Ia transeccion B, seg~n el aniOLsis de
Componentes Principales. I: primer Componente Prin-
transect B. 1: first Principal Component. II: second cipal, II: segundo Componente Principal.
Principal Component.132 JARAMILLO ET AL.
The macroinfauna low tide level (Table 2). In transect B,
Twenty-three and 21 taxa were counted high values of density were found in both
from transects A and B, respectively. zones, with the low tide level station show-
In both transects, Peracarid crustaceans ing the highest value (Table 2). One-way
(isopods, amphipods, cumaceans) were the analysis of variance indicates significant
most diverse group with 13 and 11 species differences (P < 0.05) between the inter-
respectively. Macroinfauna density increas- tidal and subtidal zones of A (excluding
ed in transect A from intertidal to subtidal low tide level from the analysis because
stations, with the highest value found at of its high density), but not in B.
TABLE 2
Queule River Estuary. Macroinfaunal density, number of species and diversity per station at
transects A and B.+ low tide level.
Estuario del Rio Queule. Densidad de la macroinfauna, numero de especies y diversidad en cada estacion
de las transecciones A y B. +nivel de marea baja.
transect A 2 3 4 5 +6 7 8 9 11
density per m2 32 96 16 128 296 6,368 424 944 952 752 528
number of species 2 1 1 3 8 9 13 14 11
diversity index 1.2 2.4 2.8 3.2 2.4 2.3
transect B 2 3 4 +5 6 7 8 9
density per m2 16 288 37,472 11,584
number of species 7 9 8 8 9 9 7 7 9
diversity index 2.6 1.6 1.1 1.5 1.8 1.8 1.9 1.7
In transect A, there was a tendency of species (12 out of 21 taxa), while poly-
increasing number of species and diversity chaetes (Hemipodus sp., Glyceridae) were
from low intertidal to subtidal levels, while the most abundant organisms in the subtid-
in transect B . the number of species and al faunal assemblage. This distinct break
values of diversity were similar in both between intertidal and subtidal assemblages
levels (Table 2). Significant differences is also shown by the dendrogram produced
of diversity on both levels < with Winer's Index (Fig. 6). Intertidal and
Wilcoxon test) were found only in subtidal stations are arranged in two
transect A. In this transect, intertidal distinct groups linked at a very low value
stations 2, 3 and 4 have a 0 diversity of similarity (0.08). Station 6 (the low
value, due to the presence of only one tide level) is not included in any of the
species, the isopod Excirolana hirsuticau- two groups because of its high abundance
da (Fig. 4 ). A similar situation was detected (given by Euzonus sp. and the bivalve
in the high intertidal of transect B (station Mesodesma donacium) in relation to the
1) where a single species was collected, the other intertidal or subtidal stations.
dipterous Limonia sp.
In transect A, the low tide level clearly In transect B (Fig. 5), on the other
separated an intertidal faunal assemblage hand, there is no marked faunal break
from a subtidal one (Fig. 4). Cirolanid between the intertidal and subtidal zones.
isopods (Excirolana hirsuticauda and Exci- Three of the most abundant species (Mi-
rolana monodi) were the most characte- nuspio chilensis, Spionidae; Perinereis gual-
ristic taxa of upper and middle intertidal, pensis, Nereidae (Polychaeta) and Paraco-
while the polychaete Euzonus sp. (Ophe- rophium chilensis Corophiidae (Amphi-
liidae) was the most abundant species at poda)) inhabited both zones and showed
the lower intertidal. Peracarids were the their highest abundance in the upper levels
organisms with the highest number of of their distribution (Fig. 5). Other taxa,MACROINFAUNA IN A CHILEAN ESTUARY 133
A Excirolana hirsuticauda (I)
Excirolana monodi (I)
Euzonus s p. ( P)
donacium ( 8)
- - ChHXV sp. (A)
Macrochiridothea mehuinensis (I)
Polychaeta A ( P)
EdoWea dahli ( I )
Phoxocephalopsis mehuinensis (A)
magellanicus (A)
Mulinia (B)
sp. ( P )
NephWys impressa ( P)
lsopoda sp. (I )
ChaetiOia paucidens (I )
Sera/is gaudichaudii (I J
Polychaeta 8 ( P)
Polychaeta C ( P)
Oedicerotidae sp. (A)
Diaslylis s p. ( C )
Boccardia sp. ( P)
Gammaridae A (A)
Gammaridae 8 (A)
LT
l l
2 3 4 5 6 7 8 9 10 11
stat ions
Fig. 4: Queule River Estuary. Transversal distri- Estuario del Rto Queule. Distribucion transversal de Ia
bution of the macroinfauna at transect A: (I) macroinfauna en Ia transeccion A: (I) lsopoda, (A)
Anfipoda, (C) Cumacea, (B) Bivalvia y (P) Polichaeta.
Isopoda, (A) Amphipoda, (C) Cumacea, (B) LT: nivel de marea baja. Escala: numero de animales por
Bivalvia and (P) Polychaeta. LT: low tide level. m2.
Scale: number of animals per m2 .134 JARAMILLO ET AL.
B
Anlocha sp.( In l
Staphyllinidae sp. (In l
Limonia (In)
Collembola sp.(ln)
i lsopoda sp. (I)
Exciro/ana hirsulicauda (I)
Paracorophium (A)
sp. (A )
Corophidae sp.(A)
gua/pensis ( P)
Minuspio chi/ensis ( P)
sp.
sp.(P)
Mulinia edu/is ( B)
Kingie/la chilenica (8)
Ostracoda sp
sp. (A)
dicerotidae sp. (A)
Gammaridae C (A)
Gammaridae (A )
Gamm aridae E (A)
LT
!
2 3 4 5 6 7 8 9
stations
FIG. 5: Queule River Estuary. Transversal distri- Estuario del Rio Queule. Distribucion transversal de Ia
bution of the macroinfauna at transect B: (I) macroinfauna en Ia transeccion B: (I) Isopoda, (A)
Anfipoda, (C) Cumacea, (B) Bivalvia y (P) Polichaeta.
lsopoda, (A) Amphipoda, (B) LT: nivel de marea baja. Escala: numero de animales
Bivalvia and (P) Polychaeta. LT: low tide level. por m2.
Scale: number of animals perm 2 .MACROINFAUNA IN A CHILEAN ESTUARY 135
such as the bivalve Kingiella chilenica, stations, including both intertidal and
and one species of Capitellidae (Polychae- subtidal levels and linked at a value of
ta), also occupied intertidal and subtidal 0.51. Station 1, with only one species
levels (Fig. 5). The dendrogram for this (Limonia sp.) is separated from the rest
transect (Fig. 6) shows two groups of of the stations.
®
+ +
1 2 3 4 5 7 9 8 11 6 1 3 2 6 7 8 9 5 4
Sw o.5
intertidal stations
+ low tide level
subtidal stations
Fig. 6: Queule River Estuary. Dendrograms of transects A and B and produced by weighed pair group
method with Winer's Similarity Index.
Estuario del Rto Queule. Dendrograma de las transecciones A y B producidos por el pair group
y basado en el Indice de Similitud de Winer.
The distribution and abundance of the
soft bottom macroinfauna has been related
Results show a distinct difference in com- to the quality of the substrate (see reviews
munity structure of intertidal and subtidal from Gray 1974, 1981). In this study,
zones near the mouth of the Queule River the species discontinuity between the
Estuary, while in the upper estuary, many intertidal and subtidal zones of transect
of the numerically dominant species A, was not correlated to sedimentary
(Minuspio chilensis, Perinereis gualpensis parameters whose values did not show
and Paracorophium chilensis) were found significant differences between both zones.
in both zones. Persistent abundances of The latter situation was also reflected in
those species, together with similar di- the results of the Principal Component
versity values through transect B, show Analysis, which did not show a clear se-
that intertidal and subtidal zones of the paration between stations of the intertidal
upper part of the estuary have similar and subtidal zone. An alternative expla-
species composition, as has been shown nation for that discontinuity is submer-
in certain sandy bottoms of the northern gence and its control over the length of
hemisphere (Croker 1977, Croker et al. time available for feeding (Newell 1979).
1975, Fincham 1971, Knott et al. 1983 For example, the upper limit of distri-
and Mc,ntyre & Eleftheriou 1968). bution of suspension feeders on transect136 JARAMILLO ET AL.
A may be determined by that tide level south Chilean coast has been characterized
at which sufficient food can be obtained as dominated by peracarid crustaceans:
for growth and reproduction (Newell cirolanid isopods and talitrid amphipods
1979). On the other hand, variations of (Bertran 1983, Jaramillo 1978, 1982).
physical factors in the intertidal zone In this study, cirolanids were found in the
(e.g. temperature and water content of upper, middle and lower levels of transect
the sediment) may also be important A (Fig. 4) as mentioned by Bertran (1983)
for determining the upper limit at which and by Jaramillo (1978), for the sandy
subtidal species can survive. A search for habitats located in the outlet of the Lingue
the causative mechanisms explaining the River Estuary (6 km south of Queule
restriction of cirolanid isopods (and also River Estuary). The talitrid amphipod
talitrid amphipods) to the intertidal zone Orchestoidea tuberculata, inhabitant of
of transect A (as is typical of Chilean the upper levels of sandy areas adjacent
sandy beaches where they occur, E. J ara- to transect A was not detected in this
millo, personal observation) is more dif- study. Similarly to what was found by
ficult. Biological interactions of intertidal Bertran (1983) at the outlet of the Lingue
species with animals living near the low River Estuary, in the lower levels of tran-
tide level and/or shallow subtidal depths sect A the decapod Emerita analoga charac-
may be involved. teristic of such levels in exposed and semi-
At transect B, significant differences exposed sandy beaches (Jaramillo 1978,
were detected and supported by Principal 1982) was lacking. Concerning the inhabi-
Component Analysis for most of the se- tants of the low tide and subtidal levels,
dimentary parameters (except organic mat- a general coincidence of some amphipods
ter) between intertidal and subtidal zones. present (Cheus sp., Phoxocephalopsis me-
Yet the species composition was similar. huinensis and Bathyporeiapus magellani-
For this area of the estuary, two hypothe- cus ), was found with the schemes of Ber-
ses are suggested to explain the macroin- trin (1983) and Jaramillo (1978, 1982).
faunal continuity between these zones. The intertidal of the upper part of the
The first is related to the amount of estuary (transect B) resembles the protect-
food available for these (primarily) deposit ed beaches studied by Bertran (1983)
feeders. The similar amount of organic in the middle and upper part of the Lingue
matter along the transect would provide River Estuary. Perinereis gualpensis and
enough food to support high populations Paracorophium chilensis stand out among
of such deposit feeders at both zones. the most abundant and characteristic taxa
Therefore, the limit between the intertidal of the intertidal in Bertran' as well as in
and subtidal zone would not present a this study. However, Bertran (1983) did
food barrier in the distribution of the not report the presence of Minuspio chi-
species as suggested for the subtidal animals lensis, the most abundant species in the
living outside the mouth of the estuary. transect B and also present as an abundant
The second hypothesis is related to the taxon in other intertidal areas of the mid-
physical characteristic of the intertidal dle part of the Queule River Estuary
zone. The distribution of the macroinfauna (Turner 1984 ).
would not be affected by the harshness The intertidal zonation schemes discuss-
of the intertidal zone, due to the fact ed here could undergo temporal modifi-
that in this area of the estuary the water- cations related to physical or biological
table is at the surface of the beach. This disturbances. Jaramillo (1982) has found
fact is due to the flat profile of the inter- evidences of variations to the scheme
tidal zone and the amount of organic proposed in 1978 for exposed sandy beach-
detritus which tend to clog the interstices es of southern Chile. Variations were con-
and slow down drainage, a situation which temporaneous with changes in the topo-
graphy of the beach and seasonal fluctua-
is different in the intertidal of transect tions of physical factors, e.g. temperature
A where the water table is deeper. In this and water content of the substrate. Even
way, wide variations in the physical con- though the topographic dynamics in the
ditions of the sediment (e.g. temperature intertidal of transect A is not as strong
and water content) can be avoided. as that observed in the exposed beaches
The intertidal macroinfauna of exposed studied by Jaramillo (1982), sediment
and semiexposed sandy beaches of the erosion and deposition and contempora-MACROINFAUNA IN A CHILEAN ESTUARY 137
neous macroinfaunal changes are obser- EMERY KO (1961) A simple method of measuring
vable. For example, we can mention the beach profiles. Limnology and Oceanography
effect of the sand movement during depo- 6:90-93.
FINCHAM AA (1971) Ecology and population studies
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numbers of the bivalve are stranded and graphy Marine Biology Annual Review 12:223-
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