Biotic and Abiotic Structure in the Pelagic Environment: Importance to Small Fishes

Abstract

The importance of biotic structures of a wide size range (eg marine snow, jellyfish, drift algae) and interactions between biotic and abiotic (oceanographic features) structures in the pelagic environment are discussed. Fish representing 73 families are associated with structures as larvae or pelagic juveniles. There is, however, a good body of evidence for only 16 families. A consequence of the presence of structures may include the redistribution of food and a change in the behaviour of predators. -from Author

Full text

BULLETIN OF MARINE SCIENCE,
S3(2):
393-41
S, 1993
BIOTIC AND ABIOTIC STRUCTURE IN THE PELAGIC
ENVIRONMENT: IMPORTANCE TO SMALL FISHES
M. J. Kingsford
ABSTRACT
Investigations on ichthyoplankton have traditionally focused on three broad areas of re-
search; the larval fish themselves, their prey, and their predators. Little attention, however,
has been given to the nature of the environment in which larvae are found; specifically, how
differences in the structure of pelagic habitats influence the behaviour, distribution, and
survivorship ofichthyoplankton. In addition to single structures (e.g., jellyfish) in the pelagic
environment, aggregates (e.g., marine snow) and flotsam can provide shelter and a substratum
on which ichthyoplankton may feed. The importance of biotic structures ofa wide size range
(e.g., marine snow, jellyfish, drift algae) and interactions between biotic and abiotic (ocean-
ographic features) structures in the pelagic environment are discussed. Fish representing 73
families have been demonstrated to associate with structures as larvae or pelagic juveniles.
There is, however, a good body of evidence for only 16 families. Existing research suggests
that some fish associated with structures are preflexion forms, but most are postflexion or
juvenile fish. I argue that association with structures is not the only criterion for importance.
A consequence of the presence of structures (i.e., variation in the nature of pelagic habitats)
may include the redistribution offood and a change in the behaviour of predators. Temporal
variation in the occurrence of biotic structures may alter pelagic habitats, for example, abun-
dances of some species of gelatinous zooplankton and drift algae may change according to
season. The accumulation of biotic structures in oceanographic features, such as fronts, can
confound assessments of oceanography. Research on relationships between small fish and
biotic structures rarely includes open water controls in sampling designs. Historically, the
influence that structures in the pelagic environment have on small fish has been treated as a
curiosity. Changes in concentrations of biotic structures may alter the composition oflarval
fish assemblages. Researchers need to seriously consider how different pelagic habitats influ-
ence the distribution and survivorship of small fish.
Investigations on ichthyoplankton have traditionally focused on three broad
areas of research, the larval fish themselves, their prey, and their predators. The
nature ofthe pelagic habitat in which larvae are found is rarely considered. Studies
on larval fishes are broad in scope, they encompass: systematics (Fahay, 1983;
Leis and Trnski, 1989; Matarese et aI., 1989); evolutionary relationships (Moser
et ai., 1984); fine to coarse scale
«
10 km; e.g., Marliave, 1986; Leis, 1986;
Kobayashi, 1989; Kingsford et aI., 1991) or coarse to mesoscale (10 to 1,000 km;
e.g., Ahlstrom et aI., 1976; Sherman et aI., 1984) distribution patterns, which are
often related to physical oceanography (Legendre and Demers, 1984; Kingsford,
1990); aging (Jones, 1986); sensory abilities (Blaxter, 1986; Blaxter and Fuiman,
1990); health or condition oflarvae (Theilacker and Watanabe, 1989); estimates
of the size of a fish stock (Saville, 1964; Lasker, 1985) and aquaculture (Jones,
1981). Moreover, since Hjort's (1914) suggestion that abundant planktonic food
is critical for fish larvae if they are to avoid starvation, investigations on the diet
of fish larvae, the importance of food for survival, and the distribution of prey
have been the focus of considerable attention (Lasker, 1974; Cushing, 1975; Houde
and Lovdal, 1984). In the last 2 decades, predation has been implicated as im-
portant for determining the number offish that survive early life. This has become
increasingly linked with studies on the health and feeding of larvae, as larvae are
clearly more vulnerable to predation when in a poor state of health (see reviews
by Hunter, 1981; Purcell, 1985; Bailey and Houde, 1989).
393

394
BULLETIN OF MARINE SCIENCE. VOL. 53, NO.2, 1993
Detailed studies have been made on the influence of habitat structure on the
distribution and survivorship of adult fish in a variety of marine environments
(e.g., Choat and Ayling, 1987; Sainsbury, 1988; Holbrook et al., 1990). Little
attention, however, has been given to the nature of the environment in which fish
larvae and pelagic juveniles are found. Specifically, how differences in the structure
of pelagic habitats influence the behaviour, distribution and survivorship ofichth-
yoplankton. There is a well recognized size hierarchy of planktonic organisms
(i.e., bacteria to schyphomedusae; Fenchel, 1988). In addition to single structures
in the pelagic environment, aggregates (e.g., phytoplankton and marine snow) and
flotsam can provide shelter and a substratum on which ichthyoplankton may feed.
The purpose of this paper is to discuss the importance of biotic (e.g., marine
snow, jellyfish, drift algae) and abiotic (oceanographic features) structure in the
pelagic environment to small fishes. The literature is reviewed and new data are
presented. Biotic structures clearly have a great influence on the nature of the
pelagic habitat in which small fishes are found, and the sampling of them may
give increased resolution to descriptions oflarval fish assemblages (e.g., Richard-
son et al., 1980). Furthermore, the concentrations of biotic structures are often
intensified by oceanographic features and can strongly influence the composition
of assemblages ofsmall fishes. Types of biotic structures and their abundance are
discussed as well as ontogenetic changes in the use of them by small fishes. I
consider temporal and spatial variability in the occurrence of drifting objects and
slow moving gelatinous zooplankton. Temporal variation in concentrations of
objects in the pelagic environment may be responsible for dynamic change in the
composition of assemblages of small fishes. Emphasis is also given to interactions
between oceanographic features and the concentrations of biotic structures and
problems relating to sampling.
METHODS
Counting Drift Algae and Scyphomedusae. - Estimates of the abundance and species composition of
drift algae were obtained at nine stations (l through 9) around the northeastern coast of New Zealand
1982-1984 (Fig. I). Seasonal patterns in the abundance of drift algae were examined at four sampling
stations (A through D) on a transect that extended 18 km in a northeastern direction from Leigh (Fig.
I). At all stations, sampling was carried out within a 2-km zone of each station point. Distance from
shore was: Station A,
<
100 m; Station B, 400 to 800 m; Station C, 10 km; Station D, 18 km. Clumps
of algae were counted and their weight estimated on a number of occasions over a period of 2.5 years
(1981 to 1984). The number of sampling times at each station were: Station A, 30; Station B, 24;
Station C, 27; Station D, 16. Algae were counted within five floating transects, each 200 x 400 m.
Floating transects were laid out on random bearings, by dropping II small drogues spaced at 20-m
intervals in a straight line. Exact spacing was achieved by towing a 20-m rope behind the boat and
dropping each consecutive drogue as the rope passed the previous one. The boat then traveled down
one side of the transect and back up the other. Clumps of algae were counted and weighed with a
spring balance. The weight of some clumps was estimated visually when considerable experience had
been gained. From October 1983 a different sampling procedure was adopted; 21 transects were used,
each 50 x 40 m, as described by Kingsford and Choat (1986). All results for locations off the
northeastern coast of New Zealand and seasonal patterns near Leigh were expressed as units per 0.8 ha.
Counts of the abundance of the scyphozoan Catostylus mosaicus (Order Rhizostomae), were made
in aggregations that were found in Botany Bay, New South Wales, Australia (December 1990 through
March 1991). An area of approximately 3 km2was searched for aggregations of C. mosaicus, which
were counted in six replicate transects, each 3 x 10 m, to a depth of I m; data are presented as number
per 30 m3. An observer sat on the bow of an inflatable boat with a 3-m pole mounted perpendicular
to the long axis of the boat. The boat travelled at speeds under 2 kn. (for ease of counting medusae)
and towed a lOom rope. Counts commenced when the boat entered an aggregation, a small drogue
was dropped overboard, and medusae were counted until the drogue passed the end of the 10-m rope.
Most medusae had a bell diameter of 100 to 150 mm.
The developmental forms of fishes that associate with scyphozoans were described by capturing
fishes around Desmonema chierchianum (Order Semaeostomae; 4 medusae, 223 fishes) off the north·

KlNGSFORD: FISHES, STRUcrURE AND PELAGIC ENVIRONMENT
395
l.---J
10km
ff!I.~,.
......
"'i'.:·
D
B
/56
.00· /
and Chicken Is
.,
Poor Knights Is
1 .•.•.••.•.\:-- 23
/:
4
~'
.
.
",
Figure 1. Map of the northeastern coast of New Zealand showing locations where drift algae were
sampled.
eastern coast of New Zealand and Catosty/us mosaicus (1 medusa, SO fishes) off the coast of New
South Wales, Australia for measurements of fish size. Fishes were captured using a diver controlled
net for Desmonema (0.2S-mm mesh) and a towed net for Catosty/us (0.5-mm mesh).
Drift algae were taken as a by-catch in neuston samples taken in waters of an estuarine front, plume,
and ocean on 12 d from 6 November to 19 December 1990, in Botany Bay, New South Wales,
Australia (project ofIGngsford and I. Suthers). Three replicate samples were taken in each water mass
on the same day. On average the net sampled 40 m' of water in a 3-min tow. The quantity of algae
was expressed as weight of algae (g) per 40 m'.
RESULTS AND DISCUSSION
Biotic Structures in the Pelagic Environment.-Historically, investigators have
perceived the pelagic environment as a size hierarchy of planktonic organisms

396
BULLETIN OF MARINE SCIENCE, VOL 53, NO.2, 1993
o
E
I I
o
c
10
2
B
10
4
105
A
10
7}.1m
--- BACTERIA
----- FLAGELLATES
----------- DIATOMS
------- TINTINNIDS
-------- MEROPLANKTONIC LARVAE
------ COPEPODS
------- FISH LARVAE
MEDUSAE ----------
----------- SINGLE CELLS PHYTOPLANKTON
------------------- .•., AGGREGATED
CELLS
MARINE SNOW-----------
CTENOPHORES--------
MEDUSAE-----------
SALPS---------
DRIFT ALGAE •. FLOTSAM
0.01 0.1
lmm lcm 10cm
1m
10m
Figure 2. Hierarchy of sizes of plankton and structures found in the pelagic environment. A, macro-
plankton
(>
2 cm); B, mesoplankton (0.2 to 20 mm); C, microplankton (20 to 200 ILm); D, nanoplankton
(2 to 20 ILm); E, picoplankton (0.2 to 2 ILm). Aggregated cells are often considered as marine snow
(Silver et aL, 1978), but are considered separately in this figure due to the extreme size of some
aggregations.
which are important as food for larger nekton (Fenchel, 1988; Fig. 2 "plankton").
There are, however, a wide variety of structures in the pelagic environment to
which fish larvae have been demonstrated to respond (Fig. 2). Structures that may
influence fishes are many and varied in size and shape and can provide fishes
with the following: an object to which they can orient; shelter; enhanced visibility
of prey (Damant, 1921; Helfman, 1981); a source of food, or a surface on which
to feed (Gooding and Magnuson, 1967; Phillips et al., 1969; Kingsford and Mil-
icich, 1987). Moreover, prey and predators may be redistributed due to changes
in the nature of pelagic habitats.
Evidence for Associations of Fishes with Structures. -It is well known that the
distribution of small and adult fishes is influenced by gelatinous zooplankters (Fig.
3), drift algae, and flotsam (e.g. Hunter and Mitchell, 1967; Dooley, 1972; Safran
and Omori, 1990). With the exception of work on gadids and scyphozoans (Hay
et al., 1990), however, ichthyoplankto10gists have treated associations of small

KINGSFORD: FISHES, STRUCTURE AND PELAGIC ENVIRONMENT 397
Figure 3. Large numbers of small Trachurus spp. associated with Desmonema chierchianum (Cy-
aneidae) off the northeastern coast of New Zealand.
fishes with structures as a curiosity rather than considering these relationships
seriously. Gelatinous zooplankters and flotsam are generally treated as a nuisance
in ichthyoplankton tows rather than considering that large numbers of small fishes
may be found in samples because these structures were present. Moreover, for
gelatinous zooplankters, there is a preoccupation with the deleterious effects of
these animals (e.g. Moller, 1984; Van der Veer and Oorthuysen, 1985) rather than
how they characterize local pelagic habitats and influence fishes in ways other
than predation.
A review of the literature on the association of small fishes with drift algae,
gelatinous zooplankton, and flotsam indicated that fish representing 72 families
have been found associated with structures in the pelagic environment as larvae
(sensu Leis and Trnski, 1989) or pelagic juveniles. This is probably an underes-
timate, since most of the work on fish attraction devices has concentrated on
adult fishes, as indicated by a recent symposium on the subject [Bull. Mar. Sci.
1989,44(2)]. It is very hard to determine from the literature whether small fishes
of some groups associate with structures or were caught in a volume of water that
included a structure. Open water controls are required to compare abundance of
fishes around objects with that in open water (e.g., Kingsford and Choat, 1985).
Nevertheless, a convincing body of evidence for associations exists for 16 of the
73 families (marked with an asterisk in Table 1). Where open water controls have
been done, the abundance of some fish around objects is an order of magnitude,
or more, than in comparative volumes of open water (Kingsford, 1992). Carangids
and members of the order Tetraodontiformes (monacanthids and balistids) are
caught in most studies, regardless of latitude. Other groups such as gadids, scor-
paenids, syngnathids, arripids, emmelichthyids, mullids, pomacentrids, kyphos-

398
BULLETIN OF MARINE SCIENCE, VOL. 53, NO.2, 1993
Table I. Families of fishes associated with gelatinous zooplankton, drift algae, and flotsam. Gelatinous
zooplankton includes medusae and salps; flotsam includes drift logs, rafts, and fish attraction devices.
Families with good evidence of association with structures in the pelagic environment are marked
with an asterisk. This decision was based on number of studies, numbers of fishes caught, and the
use of open water controls
Geographical
Family
Structure
location References
Chanidae flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubI.
tralia obs.)
Clupeidae flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubI.
tralia obs.)
Galaxiidae Drift algae Temperate New Zealand Kingsford (1992)
Engraulididae Drift algae Temperate Japan Safran and Omori (1990)
Gonostomatidae flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubI.
tralia obs.)
Myctophidae flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubI.
tralia obs.)
Antennariidae Drift algae Tropical Caribbean; Dooley
(1972);
Safran and
Temperate Japan; Omori (1990); Druce and
Temperate east coast, Kingsford (unpubl. obs.);
Australia; Great Barri- Choat and Kerrigan (unpubl.
er Reef, Australia obs.)
Gobiesocidae Drift algae, Temperate California Mitchell and Hunter (1970)
flotsam
Moridae Drift algae, Ge- Temperate New Zealand Kingsford (1992); M. J. Kings-
latinous zoo- ford (unpubI. obs.)
plankton
Bregmacerotidae flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubI.
tralia obs.)
Gadidae* Gelatinous zoo- Worldwide; Temperate Mansueti (1963); Hay et aI.
plankton
&
Subarctic east At- (1990); Davenport and Rees
lantic; temperate (1993)
Wales
Pholididae Drift algae Temperate Japan Safran and Omori (1990)
Zaproridae Gelatinous zoo- Worldwide Mansueti (1963)
plankton
Scorpaenidae* Drift algae, Temperate California; Mitchell and Hunter (1970);
flotsam Temperate Japan; Safran and Omori (1990);
Great Barrier Reef, Choat and Kerrigan (un pub I.
Australia obs.); Boehlert (1977)
Cyclopteridae Drift algae Temperate Wales Davenport and Rees (1993)
Anoplopomatidae Drift algae, Temperate California; Mitchell and Hunter (1970);
flotsam Temperate Japan Safran and Omori (1990)
Hexagrammidae Drift algae Temperate Japan Safran and Omori (1990)
Cottidae Drift algae, Temperate California Mitchell and Hunter (1970)
flotsam
Oplegnathidae Drift algae Temperate Japan Safran and Omori (1990)
Embiotocidae Drift algae, Temperate California Mitchell and Hunter (1970)
flotsam
Plotosidae Drift algae Temperate western Aus- Lenanton et aI. (1982)
tralia
Belonidae flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubl.
tralia obs,)
Scorn berosocidae Drift algae Temperate Japan Safran and Omori (1990)
Atherinidae flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubl.
tralia obs,)

KINGSFORD: ASHES, STRUcrURE AND PELAGIC ENVIRONMENT
399
Table I. Continued
Geographical
References
Family
Structure location
Exocoetidae Drift algae Tropical Caribbean; Dooley (1972); Choat and Ker-
Great Barrier Reef, rigan (unpubl. obs.)
Australia
Syngnathidae* Drift algae, Tropical Caribbean; Dooley (1972); Safran and
Aotsam Temperate Japan; Omori (1990); Mitchell and
Temperate California; Hunter (1970); Kingsford and
Temperate New Zea- Choat (1985, 1986); Kings-
land ford (1992)
Serranidae Aotsam Temperate east coast, Rountree (1990)
U.S.
Grammistidae Aotsam Temperate east coast, Rountree (1990)
U.S.
Lobotidae Drift algae, Tropical Caribbean; Dooley (1972); Hunter and
Aotsam Temperate California Mitchell (1970)
Priacanthidae Aotsam Temperate east coast, Rountree (1990)
U.S.
Teraponidae Aotsam Temperate east coast, Druce and Kingsford (unpubl.
Australia obs.)
Apogonidae Aotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubl.
tralia obs.)
Sillaginidae Drift algae Temperate western Aus- Lenanton et al. (1982); Druce
tralia; Temperate east and Kingsford (unpubl. obs.)
coast, Australia
Carangidae* Drift algae, Ge- Temperate Japan; Tropi- Yabe and Mori (1950); Dooley
latinous zoo- cal Caribbean; Sub- (1972); Gooding and Magnu-
plankton, tropical Hawaii; Tem- son (1967); Safran and Omori
Aotsam perate Japan; (1990); Kingsford (1992);
Temperate New Zea- Druce and Kingsford (unpubl.
land; Temperate east obs.); Mansueti (1963); Hun-
coast, Australia; ter and Mitchell (1967, 1968),
Worldwide; Temperate Mitchell and Hunter (1970);
California; Mississippi Phillips et al. (1969); Janssen
Sound, U.S.; Temper- and Harbison (1981); Roun-
ate Atlantic; Temper- tree (1990); Choat and Kerri-
ate east coast, U.S,; gan (unpubl. obs.)
Great Barrier Reef,
Australia
Lutjanidae Aotsam Temperate east coast, Rountree (1990); Choat and
U.S.; Great Barrier Kerrigan (unpubl. obs.)
Reef, Australia
Nemipteridae Aotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubl.
tralia obs.)
Haemulidae Aotsam Temperate east coast, Rountree (1990)
U.S.
Sparidae Gelatinous zoo- Temperate Atlantic; Janssen and Harbison (1981);
plankton Temperate east coast, Druce and Kingsford (unpubl.
Australia obs.)
Sciaenidae Aotsam Temperate east coast, Rountree (1990)
U.S.
Gerreidae Aotsam Temperate east coast, Druce and Kingsford (unpubl.
Australia obs.)
Arripidae* Drift algae Temperate western Aus- Lenanton et al. (1982); Kings-
tralia; Temperate New ford (1992)
Zealand

400
BULLETIN OF MARINE SCIENCE, VOL. 53, NO.2, 1993
Table I. Continued
Geographical
Family Structure
location
References
Emmelichthyidae* Drift algae Temperate New Zealand Kingsford (1992)
Coryphaenidae Drift algae, Temperate Japan; Sub- Yabe and Mori (1950); Gooding
flotsam tropical Hawaii; Trop- and Magnuson (1967); Dooley
ical Caribbean; Tem- (1972); Druce and Kerrigan
perate east coast, (unpubl. obs.); Hunter and
Australia; Temperate Mitchell (1967, 1968); Choat
California; Great Bar- and Kerrigan (unpubl. obs.)
rier Reef, Australia
Ambassidae flotsam Temperate east coast, Druce and Kingsford (unpubl.
Australia obs.)
Holocentridae flotsam Subtropical Hawaii; Gooding and Magnuson (1967);
Great Barrier Reef, Choat and Kerrigan (unpubl.
Australia obs.)
Mullidae* Drift algae, Subtropical Hawaii; Gooding and Magnuson (1967);
Flotsam Temperate New Zea- Kingsford
(J
992);
Kingsford
land; Temperate Cali- and Choat (1985, 1986); Hun-
fornia; Temperate east ter and Mitchell (1967, 1968);
coast, Australia; Great Druce and Kingsford (unpubl.
Barrier Reef, Australia obs.); Choat and Kerrigan
(unpubl. obs.)
Pomacentridae* Drift algae, Subtropical Hawaii; Gooding and Magnuson (1967);
flotsam Tropical Caribbean; Dooley (1972); Safran and
Temperate Japan; Omori (1990); Mansueti
Worldwide; Temperate (1963); Mitchell and Hunter
California; Temperate (1970); Hunter and Mitchell
east coast, Australia; (1967,1968); Druce and
Great Barrier Reef, Kingsford (unpubl. obs.);
Australia Choat and Kerrigan (unpubl.
obs.)
Pomacanthidae flotsam Temperate east coast, Rountree (1990)
U.S.
Girellidae Drift algae, Worldwide; Temperate Mansueti (1963); Kingsford and
flotsam, Ge- New Zealand; Tem- Choat (1985, 1986); Kings-
latinous zoo- perate California ford (1992); Mitchell and
plankton Hunter (1970)
Kyphosidae* Drift algae, Subtropical Hawaii; Gooding and Magnuson (1967);
flotsam Tropical Caribbean; Dooley (1972); Mitchell and
Temperate California; Hunter (1970); Hunter and
Temperate New Zea- Mitchell (1967, 1968); Kings-
land; Great Barrier ford (1992); Choat and Kerri-
Reef, Australia gan (unpubl. obs.)
Mugilidae* Drift algae, Temperate western Aus- Lenanton et al. (1982); Kings-
flotsam tralia; Temperate New ford (1992); Safran and Omo-
Zealand; Temperate ri (1990); Hunter and Mitchell
Japan; Temperate Cal- (1967, 1968); Kingsford and
ifornia; Temperate Choat (1985, 1986); Druce
New Zealand; Tem- and Kingsford (unpubl. obs.)
perate east coast, Aus-
tralia
Sphyraenidae flotsam Temperate east coast, Druce and Kingsford (unpubl.
Australia; Great Barri- obs.); Choat and Kerrigan
er Reef, Australia (unpubl. obs.)
Polynemidae Drift algae, Temperate California Hunter and Mitchell (1967,
flotsam 1968); Mitchell and Hunter
(1970)
Labridae Drift algae, Temperate New Zealand; Kingsford (1992); Rountree

KINGSFORD: ASHES, STRUCTURE AND PELAGIC ENVIRONMENT 401
Table 1, Continued
Geographical
Family
Structure
location
References
Flotsam Temperate east coast (1990); Choat and Kerrigan
U.S.; Great Barrier (unpubl. obs.)
Reef, Australia
Pinguipedidae Flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubl.
tralia obs.)
Blenniidae* Drift algae, Temperate California; Hunter and Mitchell (1967,
Flotsam Temperate New Zea- 1968), Mitchell and Hunter
land; Temperate east (1970); Kingsford (1992);
coast, Australia; Tem- Druce and Kingsford (unpubl.
perate east coast, U.S.; obs.); Rountree (1990); Choat
Great Barrier Reef, and Kerrigan (unpubl. obs.)
Australia
Tripterygiidae* Drift algae Temperate New Zealand; Kingsford (1992); Kingsford and
Great Barrier Reef, Choat (1985, 1986); Choat
Australia and Kerrigan (unpubl. obs.)
Clinidae Drift algae Temperate California; Mitchell and Hunter (1970);
Temperate New Zea- Kingsford and Choat (1985,
land 1986); Kingsford (1992)
Callionymidae Flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubl.
tralia obs.)
Gobiidae Flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubl.
tralia obs.)
Microdesmidae Flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubl.
tralia obs.)
Scombridae Drift algae, Temperate Japan; Sub- Yabe and Mori (1950); Gooding
Flotsam tropical Hawaii; Tem- and Magnuson (1967); Hunter
perate California; and Mitchell (1967,1968);
Temperate New Zea- Mitchell and Hunter (1970);
land; Great Barrier Kingsford (1992); Choat and
Reef, Australia Kerrigan (unpubl. obs.)
Istiophoridae Flotsam Great Barrier Reef, Aus- Choat and Kerrigan (unpubl.
tralia obs.)
Ammodytidae Flotsam Temperate California Hunter and Mitchell (1967,
1968)
Centrolophidae Drift algae, Ge- Temperate Japan; Safran and Omori (1990); Man-
latinous zoo- Worldwide sueti (1963)
plankton
Nomeidae* Gelatinous zoo- Subtropical Hawaii; Gooding and Magnuson (1967);
plankton, Worldwide; Temperate Mansueti (1963); Janssen and
Flotsam Drift Atlantic; Temperate Harbison (1981); Hunter and
algae California; Tropical Mitchell (1967, 1968); Dooley
Caribbean; Great Bar- (1972); Choat and Kerrigan
rier Reef, Australia (unpubl. obs.)
Stromateidae* Drift algae, Ge- Worldwide; Mississippi Mansueti (1963); Phillips et al.
latinous zoo- Sound, U.S.; Temper- (1969); Hunter and Mitchell
plankton, ate California; Tem- (1967, 1968); Janssen and
Flotsam perate Atlantic Harbison (1981)
Tetragonuridae Gelatinous zoo- Worldwide; Temperate Mansueti (1963); Janssen and
plankton Atlantic Harbison (1981)
Balistidae* Drift algae, Temperate Japan; Sub- Yabe and Mori (1950); Gooding
Flotsam tropical Hawaii; Trop- and Magnuson (1967); Dooley
ica! Caribbean; Tem- (1972); Hunter and Mitchell
perate California; (1967,1968); Choat and Ker-
Great Barrier Reef, rigan (unpubl. obs.)
Australia
Monacanthidae* Drift algae, Tropical Caribbean; Dooley (1972); Hunter and

402
Table I. Continued
BULLETIN OF MARINE SCIENCE, VOL. 53, NO.2, 1993
Family
Ostraciidae
Diodontidae
Molidae
Structure
Flotsam, Ge-
latinous zoo-
plankton
Flotsam
Drift algae
Drift algae,
Flotsam
Geographical
location
Temperate California;
Mississippi Sound,
U.S.; Temperate Ja-
pan; Temperate New
Zealand; Temperate
east coast, U.S.; Great
Barrier Reef, Australia
Great Barrier Reef, Aus-
tralia
Tropical Caribbean
Temperate California
References
Mitchell (1967,1968); Phil-
lips et al. (1969); Safran and
Omori (1990); Kingsford and
Choat (1985, 1986); Kings-
ford (1992); Rountree (1990);
Choat and Kerrigan (unpubl.
obs.); M. J. Kingsford (pers.
obs.)
Choat and Kerrigan (unpubl.
obs.)
Dooley (1972)
Mitchell and Hunter (1970)
[Adult only}
ids, mugilids, blenniids, tripterygiids, stromateids, and nomeids are caught around
objects in high abundance in some parts of the world.
Although many species of carangids, gadids, and monacanthids associate with
pelagic structures, this is unusual for most families. For example, of the species-
rich family Pomacentridae, most records of individuals around objects are for
members of the genus Abudefduf Similarly, for the family Tripterygiidae some
genera (e.g., Gilloblennius spp.) have a strong association with objects, whilst other
members of the genus Tripterygion are generally found in highest abundance in
open water (Kingsford, 1992). It needs to be reiterated, however, that our knowl-
edge of associations between small fishes and objects is poor and the list I have
given here is by no means definitive.
Gelatinous Zooplankters. -Medusae are abundant in many parts of the world and
potentially have a significant influence on the nature of the pelagic habitat for
fishes and other zooplankters (Mansueti, 1963; Dahl, 1961). For example, the
scyphozoan Catostylus mosaicus (Order Rhizostomeae) regularly reaches densities
of2 to 7 per 30 m
3
in aggregations and on occasions up to 68 per 30 m
3
in sheltered
waters of New South Wales, Australia (Table 2). Aside from direct effects of
preying on small fish larvae (Bailey and Houde, 1989), medusae may influence
the fate of fishes by providing shelter or food; they may move associated fishes
to areas of high food abundance or cause local reductions in the abundance of
planktonic food. Large ctenophores may also influence the distribution and be-
haviour of small fishes. For example, presettlement monacanthids will eat cteno-
phores (Kingsford and Milicich, 1987).
Little information is available on the positive aspects of medusae in the pelagic
environment and how they relate to fish. A notable exception is the work of Hay
et al. (1990) on the abundance ofScyphozoans (Cyanea spp.) and "O-group" gadoid
Table 2. Abundance (mean
±
SE) of scyphomedusae Catostylus mosaicus in separate aggregations
found in Botany Bay, New South Wales, Australia; number per 30m
3
20 December 1990
68
±
14
5.3
±
2.5
15 February 1991
3
±
0.7
19 March 1991
6.6 ±0.7
3.6
±
1.0
1.4
±
0.7
3.6
±
0.3

KINGSFORD: FISHES, STRUcrURE AND PELAGIC ENVIRONMENT
403
fishes. Positive correlations between the abundance of Cyanea capillata and four
species of gadoids were regularly found over a period of 10 years. The authors
argued that fishes unable to associate with Cyanea may have poorer prospects of
survival. They also note that Cyanea may provide a substratum on which to feed.
Drift Algae and Flotsam. -Drifting algae are found in sufficient quantities to
influence the nature of pelagic habitats. Sargassum is typically the main species
of drift in tropical waters (Dooley, 1972), while extensive mats of laminarian
algae particularly Macrocystis pyrifera (Mitchell and Hunter, 1970) are found in
cold temperate waters. Other species of macroalgae which commonly drift, include
the laminarians Nereocystis and Pelagophycus and the fucoids Durvillea, Cysto-
seira, and Ascophyllum (Foster and Schiel, 1985). In temperate to subtropical
waters of the world fucoid algae abound as drift near the mainland and offshore
islands. Sargassum spp. and Phyllospora comosa are the common species found
drifting off the coast of New South Wales, Australia (pers. obs.). Off the coast of
northeastern New Zealand, the three species of Carpophyllum, C. maschalocarpum,
C. j/exuosum, and C. plumosum, as well as Sargassum spp. and Cystophora, are
the most abundant types of drift algae at locations separated by up to 110 km
(Table 3). Maximum densities in this study reached 8,026 g per 0.8 hectares.
Similar to the study of Kingsford (1992), most clumps of algae were under 500
g. Clumps of algae as small as 5 g can influence the distribution of fishes (Kingsford
and Choat, 1985, 1986). The large standard errors for data in Table 3 indicate
the patchy distribution patterns of drift algae. Algae were often concentrated in
three transects or less, rather than being evenly distributed among all transects.
It should be noted that unlike the static distribution patterns of many habitats in
environments such as soft sediments or reefs, structures in the pelagic environment
move around and influence fish over a broad area. Furthermore, fish generally
found offshore may be transported onshore in some conditions (Kingsford and
Choat, 1986).
In other parts of the world where riverine influences on coastal environments
are intense, flotsam, such as logs, may have a great effect on the types of structures
in the pelagic environment. Limbs, and in some cases whole trees, are washed
down large rivers (Hunter and Mitchell, 1967). In polar regions icebergs may
influence the distribution of small fishes, as Hamner et aI. found (1989) for eu-
phausids.
Aggregates and Their Relevance to Fishes. - There are many structures in the
pelagic environment whose relevance to fishes is poorly known. Large phyto-
plankton cells are as large as small larvae (Fig. 2), while aggregates of cells of a
variety of sizes can significantly alter the nature of the pelagic environment.
Phytoplankton often aggregates (Ki0rboe et aI., 1990) or forms rafts of a range of
sizes (3 to 10.6 cm; Alldredge and Silver, 1982). Blue-green algae, such as Osci/-
latoria erthraeus along the coast of eastern Australia, can form extensive patches
or slicks kilometers in length (Oliver and Willis, 1987; Kingsford et aI., 1991).
Although copepods have been demonstrated to use Oscillatoria spp. as a sub-
stratum (Bottger-Schnack and Schnack, 1989), there is little information on how
it affects small fishes. Aggregates of coral spawn, that form over very short time
periods on coral reefs (e.g., Oliver and Willis, 1987), may also alter the nature of
the pelagic habitat and influence the distribution and behaviour of fishes.
The abundance and size of marine snow can have an enormous influence on
the pelagic habitat (see review by Alldredge and Silver, 1988). Abundance of
marine snow can range from 0 to 500 aggregates per liter. Although aggregates as
small as 50 ~m have been recorded, marine snow typically ranges in size from
500 ~m to lcm (A. L. Alldredge, pers. comm.). In extreme cases, larvacean houses,

404
BULLETIN OF MARINE SCIENCE, VOL. 53, NO.2, 1993
'"
=
0
0~0 0
t::
0""":
""~
.!l! ill) NOOoo N ONO N 0-
_r--t"'\N
-"" Mo--v-.oO
NNNtn-
N
"8
~l
+1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +10 +1 +1 +1 +1 +1 +1
'"
·s
.~
~
NNl.I')lI)
N"" ""Ovv"'OO
NN-V"IN
0-
I"-MVo- -0 • 0- . MMI"- V
~NN
---
0M
~
=
OIl
li:
.5 0-
""M 1"--0- M-.ol"-
~
1:.-
v N.
""
O-NOv -.OOv ••.• 0
r
v--N v
--f1"')-- Q()r')N--
""
0
:s
+1 +1 +1 +1 +10 +1 +1 +1 +1 +10 +1 +1 +1 +1 +10 +1
~[<>~
~
~'i:;
VNMN I"- I"--ov-.o
f'I""lt--OOf'-
N
-.0 00 . 0-
tnMV- ......
-("I"')OV\N
00
<.s
0...1'...-
NVM vv-
'"
.!:l
.::
"iii
0
d-
o
'0
t::
E
N~
•....
~O~f'l'ieg-
0
<.s
~§
-
.
N
\I"'lr---v
f'!
N
"iii
""-
""
N
V"If'I""l-t"--f"I"'.IV 0"'1
V r---'VM
00
~
..,<l
+1 +10 +1 +10 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1+1 +1
§ol:
~
eo.:!
0-0 N N
V("f")MVN\oVl.l')--\'oV\
M
0
.. a'"
M -.0 0-
r-.i •......
'll:t-O\v-,.....OOO
00
Z
.c
M"l.
""
.....• --'o:::t
N
-
QO
-d
0
t::
8-
<.s
:2 ~
t:
0
01
"0 "0
...
t::
Z
0
t::
I:
<.s
••.•0- I"- .!l! "0 I"-
•....
e
<il
0
:§E VNI"-""
'"
-.0 OM M
s:::
00
e
"'"""l
NOONv
-
""
NV 0'> NM.!l!
-
'"
~~ ~ +1 +1 +1 +1
"0 "0+10 ~ +1 +10 0 +10 0 +1 0 0 0 +1 ~+1
s:::
§OR
s:::
.!l!
~"
._ ('f1l.1')t"-M
'§
M
:5
N~ 0NV
=
M
.~
a'<;
~ lI"'lanM-
010
""
<.s
v
"" v. I"- 0
-
~M
~
•..
0.
~
000.
..c:'":'
00
~Q,
~
u
o~
"O~
t::
Cl
0
~~
I:§
",-.0 v -.o~~I"-~ N
~~
~e.
OO.VO 00 1"--.00'>0'>"" 0'>
0 •..•
~"
Q'l,NV")-
00 -
N-MO'\V"l("'l'1---00f'l""lM
-
o~
~j
+1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1+1 +1 +1
]U
g~
ONooO 000 MNOONt""lf'l""l-NN-r----OO v
-"0
a~
-.ol"-I"-N 00 -
O\~~N:;;
o-MNvM M
OIlS:::
0-
'"
-
-
t:: <.s
N·....;
0
"iiiS
",'-
.~~
.~
~
ca~
v"" 00
g ~
tr'lt'--_oo
""
MOO N 1"-1"-0'> -.0
::8
"'.0'>._ v
0""
voo""o"".-~ool"-VNI"-
<.s:::::
3
-~-M
NN-.oo--vV""N-.oVM M
o '-
+1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1
gbC
0
_ ::l
f-
M-.oO'>-.o 0"" 0-.0""-.0""0001"--.0 v 0'>0- N
<.sq
ooN""N 0- I"-N '" ""I"-""N """"""1"-0 0-
4::.
NO--
•...
""oo"'NO'>. 1"-""0'>
-
-.0
'1:: .-
"";r¥:i
N·
"0]
••..• s:::
o ~
~~
f
t:: ~
<.s'-
-NM"':::t"
""-.0 I"- 00
"OCl
s::: l::
= ...
~~
.Ui
~NMM""M~N ••.•MM ••.• M
MO ••.•MVV
•...
0"0
"
00000000 00
>orr~Clrf~O?>~o-p~~O?
"?
-=
..
.!.~~.b ~
•..
.0-
Cl
o~t::~<.sao~t::~<.sa <.s
<.s
0000.
0
f-; .5 oo<:~
<.s
ZQ~~~<:ZQ~~~<
~
....•

KINGSFORD: ASHES, STRUcrURE AND PELAGIC ENVIRONMENT
405
a common source of marine snow, can be up to 100 cm in length (Barham, 1979).
Particles of organic material and zooplankters aggregate on marine snow. Cope-
pods such as
Oncaea
spp. use marine snow as a substratum on which to feed
(Hamner et aI., 1975), but it is not known how fish larvae respond to marine
snow. Marine snow may provide shelter for larval fishes and have a great influence
on the distribution of planktonic food. For fish larvae and juveniles with limited
visual abilities (Blaxter and Hunter, 1982), marine snow may provide concentrated
packages of food. The association of some types of fishes with objects does not
reflect the potential importance of structures in the pelagic environment to small
plankters. For example, if small plankters aggregate or stick to marine snow, small
fishes that feed on them may have to respond to structures or starve.
The experimental addition of structures to the pelagic environment can rapidly
change the distribution patterns of some species of fishes. Free floating experi-
mental clumps of algae quickly attracted fishes and some types of invertebrates
in 1 to 6 h (Kingsford and Choat, 1985). Similar results have been found with
rafts and other types of fish accumulation devices (Hunter and Mitchell, 1968).
This suggests that the input of structures to coastal or oceanic waters can quickly
alter the distribution patterns of fishes. More experiments are required on the
colonization of all sizes of structures in the pelagic environment.
Temporal Abundance Patterns of Biotic Structures. -
The influence that some
structures have in the pelagic environment may be relatively predictable at dif-
ferent times of the year and often depends on the demography of the structures
themselves. For example, scyphozoans exhibit large peaks and troughs in abun-
dance at different times of the year according to the release of ephyrae during
strobilation. Most scyphozoans are annuals, ephyrae are released and grow a
medusoid stage quickly. Following a period of a few months in the plankton,
medusae die. In the North Sea, Van derVeer and Oorthuysen (1985) found regular
spring peaks in abundance of
Aurelia
over a period of 2 years. The size of peaks
may, however, vary among years (e.g., Moller, 1984). Similar patterns have been
found for
Cyanea capillata
(Grondahl and Hernroth, 1987) and
Phyllorhiza punc-
tata
(Order Rhizostomae; Garcia, 1990).
Abundance of drift algae may vary according to the demography of some species.
For example, drift
Sargassum
plants were only found off the northeastern coast
of New Zealand between October and February nearshore and at stations up to
18 km from the mainland (Fig. 4). This seasonality matches the time S.
sinclairii
shed most of the thallus during the late stages of reproduction over spring (Schiel,
1985). Although other species of algae in costal waters do not exhibit regular
patterns (Kingsford, 1992),
Sargassum
can be expected to influence the nature
of pelagic habitats in spring and summer. It should be emphasized, however, that
the spatial distribution patterns of drift algae are heterogeneous and dynamic even
during seasonal peaks in abundance of some species (Kingsford and Choat, 1986).
I have found little information on temporal variation in the abundance of
smaller structures in the pelagic environment, but anecdotal accounts suggest that
large patches of blue-green algae,
Oscillatoria erthraeus,
are most common off the
eastern coast of Australia during late spring and summer. Seasonal variation in
the formation of diatom aggregates and regular or irregular upwelling events
influence the production of marine snow (Prezelin and Alldredge, 1983; Alldredge
and Gotschalk, 1989). Moreover, from my own observations in coastal waters of
New Zealand and Australia and those of Alldredge (pers. comm.) off the west
coast ofthe U.S., marine snow may peak in abundance toward the end of seasonal
plankton blooms. Clearly, these changes in the abundance of structures have a
great influence on the nature of pelagic habitats.

406
BULLETIN OF MARINE SCIENCE, VOL. 53, NO.2, 1993
Ontogenetic Changes in the Use of Biotic Structures by Fishes. -Preflexion, post-
flexion, and presettlement juvenile blennies (Gilloblennius, Tripterygiidae) have
been found to associate with drift algae (Kingsford, in press). Most species of
fishes, however, appear to associate with structures for a part of their early life
history. Moreover, the majority of forms that have been found to associate with
structures, to date, are postflexion or juvenile fishes. For example, small mona-
canthids only associate with drifting algae once rays and spines of the fins are well
developed (Kingsford and Milicich, 1987). Carangids usually only associate with
structures as postlarvae and juveniles. I compared the developmental forms of
Trachurus found in association with scyphozoans in New Zealand and Australia.
Although Trachurus spp. hatch at 2 to 3 mm notochord length (Fahay, 1983), the
smallest individuals I found around scyphozoans were 9 mm (SL) and the largest
fish were over 30 mm SL (Fig. 5). It should be noted that more information is
required on the developmental forms of fishes around medusae, in case size
frequencies vary among medusae, locations, and times. Gadids also associate with
medusae, especially Cyanea capillata, as postlarvae and juveniles (Hay et a1.,
1990). Kingsford (1992) found that
Trachurus
were quickly attracted to ex-
perimental algae (I-kg clumps) suspended at a depth of 15 m. After 6.5 to 8 h,
51
±
7.1 (SE) fish were observed near each clump. Although counts were made
visually, all individuals were clearly postlarvae or larger.
Some reef fishes associate with structures in the pelagic environment as postlar-
vae and juveniles (Hunter and Mitchell, 1967; Safran and Omori, 1990; Kingsford,
1992). The occurrence and movement of structures (via winds and oceano-
graphic features) is of considerable interest for investigating the causes ofvariation
in patterns of recruitment on reefs (Kingsford and Choat, 1986). Areas in which
drifting objects regularly wash ashore may receive greatest numbers of settlers.
Interactions Between Biotic and Abiotic Structures. -Concentrations of biotic
structures are often intensified by oceanographic features. A consequence of this
is that the nature of the pelagic habitat changes considerably. Kingsford and Choat
(1986) found that drift algae were concentrated in the slicks of internal waves
under conditions with <15 knots of wind. Neuston samples taken in estuarine
fronts off the coast of New South Wales detected significant quantities of drift
algae (mainly Sargassum) on some occasions. Drift algae were present in ichthy-
oplankton samples on 9 of the 12 d that samples were taken from estuarine fronts,
waters of the plume, and on the ocean side. On 7 of these 9 d algae were found
primarily in fronts. When the mean quantity of algae in any water mass exceeded
50 g, the largest quantities were always found in fronts (Fig. 6). This makes it
more difficult to resolve whether fish were in the front because biotic structures
were present or because oceanographic features influenced them.
Pollutants such as rafts of oil and associated leachates may have a deleterious
effect on fish. Shanks (1987) found tar balls accumulated in the slicks of internal
waves. Although he did not study fishes, this anthropogenic source of structures
is another type that may influence fishes and alter the way in which they respond
to oceanographic features.
Scyphozoans in surface convergence zones have been reported for their potential
predatory influence on small fishes (Turner et al., 1985), but their role as a habitat
for fishes may be particularly important. Carangids were most abundant in Lang-
muir circulations that contained scyphozoans in a study by Kingsford et a1.(1991).
Those authors warned, however, that data should be treated with caution due to
heterogeneous variances. Hamner and Schneider (1986) also found high densities
of medusae (Aequorea. Staurophora, Aurelia, Chrysaora, and Cyanea) in Lang-

KINGSFORD: FISHES, STRUcrURE AND PELAGIC ENVIRONMENT
407
JFMA
w
«
C)
....J
«
u.
o
en
~
«
c:
C)
500
o
2000
•••, -, •••••••••••••••,"""'T,"""'T,"""'T,_, _, .." •••••••••••••••,_, ••••• , ••.•••••, _, _, ••••,••••••••,_, ••••••••••••••, _, _, •••,_ ••••••• _.
NDJFMAMJJASONDJFMAMJJASONDJ
C)
•..
,
-,
...•
,
•......•
,
.....
,
.....•.
,
....•.
,
-,
-,
-,
•......•
,
....•
,
.....•.•....•.
,
-,
-,
...•••......••
-,
.....•.
,
.....•..
,
-,
.."
•....••.....•.•....•..
-
...•.
NDJFMAMJJASONDJFMAMJJASONDJ
1981 1982 1983
MONTH
Figure 4. Temporal variation in the abundance (grams per 0.8 ha,
±
I SE) of drift Sargassum sinclairii
off the coast of northeastern New Zealand. a) Station A, < 100 m from shore; b) Station B, 400 to
600 m from shore; c) Station C, 10 km from shore; d) Station D, 18 km from shore.

408
BULLETIN OF MARINE SCIENCE, VOL. 53, NO.2, 1993
muir circulations, but mentioned nothing about fishes. Subsurface oceanographic
discontinuities, such as thermoclines and haloclines, may also form areas of con-
centration. Scypohzoans actively migrate both horizontally and vertically (Malej,
1989), which may be in response to the sun (for photosynthesis, e.g., Mastigias,
Hamner et aI., 1982) or concentrations of food (Haney, 1988). Fishes associated
with medusae may not only receive shelter and food, such as hyperid amphipods
that also associate with them, but may profit from the movement or drift of
medusae into thermoclines or convergences (e.g., Hamner and Schneider, 1986)
where planktonic food often accumulates (Nash et aI., 1987).
The accumulation of objects makes it difficult to establish the influence ocean-
ography has on the distribution of fishes without confounding it with the presence
of structures. Kingsford and Choat (1986) sampled ichthyoplankton with towed
nets as well as estimating the abundances of drift algae in and out of the slicks of
internal waves. In that study, however, no algae were in ichthyoplankton samples
to possibly confound comparisons between waters of slicks and adjacent rippled
water. Kingsford et al. (1991) had a similar dilemma in a study on topographic
fronts around reefs. Blue-green algae were very common in fronts, but not in
rippled waters adjacent to fronts. The authors attempted to resolve the conundrum
by correlations between the quantity of blue-green algae and numbers of fishes.
Numbers of small reef fishes and pelagic fishes showed no significant correlations
with volume of blue-green algae. In addition, no significant results were found
for early stages (preflexion and flexion) or late stages (postflexion and juvenile
fishes). It was concluded that the topographic fronts were responsible for high
concentrations of fishes rather than the presence of blue-green algae. Ideally,
sampling should be done in and out of oceanographic features in the presence
and absence of biotic structures.
The presence of structures in oceanographic features is a multifaceted problem.
Various groups of fishes are attracted to biotic structures in the pelagic environ-
ment regardless of the presence of oceanographic features. A consequence of
advection of structures or active movement of structures (e.g., jellyfish) into con-
vergences at the surface or deeper in the water column is that fishes associated
with structures become concentrated in these areas. Hence, fishes may concentrate
in convergences because they accompany biotic structures. Alternatively, fishes
are attracted to fronts because of high concentrations of structures andlor plank-
tonic food. Characteristic "assemblages" of small fishes may be found at frontal
regions due to the presence of structures. Hence, assessments of the abundance
of biotic structures are required in and near fronts and other oceanographic fea-
tures.
Sampling Fishes Associated with Biotic Structures. -Our lack of understanding
about the importance of structures in the pelagic environment to fishes, is partly
due to the sampling methods we have traditionally used. Certainly for marine
snow and small aggregates of cells, it is well known that the recognition of their
presence and our perception of the importance of these structures progressed
rapidly when alternative methods to plankton nets were used for sampling (Ham-
ner et aI., 1975; Silver et aI., 1978; Alldredge and Silver, 1988). Many aggregates
and delicate gelatinous zooplankters disintegrate and become unrecognizable
structures in nets. Direct visual methods of sampling (with SCUBA or submers-
ibles) were required to examine these structures. Large structures in the pelagic
environment are generally treated as a nuisance by ichthyologists, rather than of
inherent biological interest. Scyphozoans, salps, and drift algae rank highly in the
nightmares of persons towing plankton nets. With the exception of studies on

KINGSFORD: FlSHES, STRUCTURE AND PELAGIC ENVIRONMENT
409
35
30
a)
N
=
223
25
20
15
10
5
>-
0
0
Z
510 15 20 25 30 35
w
::)
0
w
a:
u.
10
b)
N
=
80
8
6
4
2
05 10 15 20 25 30 35
1MM
SIZE CLASSES
Figure 5. Size frequency of Trachurus spp. found in association with scyphomedusae in a) New
Zealand, Desmonema chierachianum and b) Australia, Catostylus mosaicus.
predation, they are usually thrown out of nets with scant regard for the influence
they may have on the numerical abundance and size frequency of fishes in the
catch, as well as variance among replicate tows. Furthermore, users of ichthyo-
plankton nets may actively avoid structures in open water to avoid fouling nets.
For us to assess the importance of structures in the pelagic environment, there

410 BULLETIN OF MARINE SCIENCE, VOL. 53, NO.2, 1993
are a number of considerations for sampling: I) Approaches to sampling, other
than towing nets, are required to adequately sample structures. Methods may
include visual counts (Hamner et a1., 1975), plankton-mesh purse seine nets
(Kingsford and Choat, 1985), and video gear (Alldredge and Silver, 1988). 2)
Structures must be incorporated into sampling designs, rather than just being
taken as a by-catch. 3) The influence of structures in the pelagic environment can
only be determined by including appropriate controls in sampling designs. 4)
Relationships between the size of structures and their influence on fishes needs
to be investigated (Kingsford and Choat, 1985; Safran and Omori, 1990).
Sampling (number 3 above) must be stratified according to the presence and
absence of structures (Green, 1979; Andrew and Mapstone, 1987). Stratified ran-
dom sampling (sensu Andrew and Mapstone, 1987) may be used where strata
include open water controls (Kingsford and Choat, 1985). If investigators have
some knowledge of the area influenced by structures versus open water, propor-
tional stratified sampling may be used where the allocation of samples is made
in proportion to the area of each stratum. However, because of the movements
of pelagic habitats, this procedure can be logistically difficult. Optimal stratified
sampling (sensu McCormick and Choat, 1987) may be used to estimate total
numbers of fishesassociated with structures compared to numbers in open water.
This procedure, however, requires two phases: (i) knowledge of the area of each
stratum and stratified random sampling for information on variation in abundance
and; (ii) allocation of sampling units according to information from (i). However,
the position, quantities, and numbers of fishes associated with structures may
change quickly. Accordingly, the time taken to analyze the results of phase (i) and
calculations for the allocation of sampling units for phase (ii) may no longer be
appropriate.
The use of structures for experiments in the pelagic environment can help with
the interpretation ofthe importance of structures to fishes. The speed with which
the distribution of fishes is influenced by the addition of structures can be measured
(Kingsford and Choat, 1985; Kingsford, 1992). Moreover, experimental treat-
ments can be stratified according to different oceanographic features. Colonization
rates of fishes to structures may be higher in convergences than in adjacent waters.
Experiments need to be done using free drifting structures (Kingsford, 1992),
rather than tethered structures (Hunter and Mitchell, 1968). Natural structures
move freely in the ocean, while tethered structures often encounter problems with
currents that small fishes may be incapable of swimming against for long periods.
Fishes that are difficult to capture using other means can be sampled using
floating objects. Many of the fishes that have been found in association with
objects are postflexion larvae or pelagic juveniles. These forms are notoriously
difficult to sample due to their avoidance of nets. Our knowledge of the early life
history of many species and their distribution patterns may be greatly enhanced
by the use of sampling approaches other than conventional ichthyoplankton nets.
Sampling structures and the use of light traps (Doherty, 1987) offer useful alter-
natives. Small fishes caught around structures are generally in good condition and
may be used for validation of daily aging experiments (Kingsford and Milicich,
1987) and other aquacultural applications. It is particularly important that in-
vestigators accurately describe the developmental phase of fishes associated with,
or influenced by, structures, since conventional classifications of "larvae" do not
encompass the full developmental range (see Kingsford, 1988); many are juveniles
that have not settled into nursery habitats.

KlNGSFORD: FISHES, STRUCTURE AND PELAGIC ENVIRONMENT 411
1000 -
(a)
800 ~
600 ..
400~
200~
0
M
~
o
~
a:
w
a..
w
~
C)
.-J
~
.-
u..
a:
o
u..
o
(J)
~
~
a:
C)
80
60
40
20
o
(b)
400
(c)
300
200
100
0PLUME FRONT OCEAN
WATERMASS
Figure 6. Abundance
(±
I SE) of drift algae in waters of plume, estuarine front, and ocean on three
occasions (a-<:) in a 6-km area around Botany Bay, New South Wales, Australia (6 November 1990
to 19 December 1990).

412 BULLET[N OF MAR[NE SCIENCE, VOL. 53, NO.2, [993
CONCLUSIONS
There is an increasing awareness that larval fishes and pelagic juveniles are
more substratum associated than previously thought. Their sensory and locomotor
abilities allow them to respond to and stay near land (Marliave, 1986; Kingsford
and Choat, 1989), stay in oceanographic features (Shanks, 1983; Kingsford and
Choat, 1986), and to associate with structures such as gelatinous zooplankton and
drift algae (Hunter and Mitchell, 1967; Janssen and Harbison, 1981; Safran and
Omori, 1990). Moreover, our perception of the pelagic environment is changing.
The ocean is not simply a bath of plankters of different sizes, but is often char-
acterized by structures of a wide range of sizes to which fishes may respond or
by which they may simply be influenced. Structures range in size from single cells
and aggregates of phytoplankton to patches of drift algae and other large flotsam.
Concentrations of some structures have regular temporal peaks in abundance and
may reach greatest densities in oceanographic convergence zones. Although dom-
inant biotic components are often used to describe habitats in other environments
(e.g., kelp forest; Underwood et aI., 1991), this has not been the case for the pelagic
environment.
It has been emphasized that the association of fishes with objects should not
be considered to be the only criterion for ecological importance. Structures, such
as marine snow, may influence the spatial distribution patterns of planktonic food,
and if fish larvae are incapable of feeding on potential prey that are adhering to
these structures, their growth rate and chances of survival may decrease. Variation
in the concentration of structures, therefore, may cause large changes to the com-
position of assemblages of small fishes. There is a great body of evidence that
oceanographic features have an important influence on the distribution, feeding,
and survivorship of fishes (see reviews by Legendre and Demers, 1984; Kingsford,
1990). The most informative investigations on the influence that abiotic structures
have on fishes have all involved stratified sampling. Investigators have been slow
to apply these principles to biotic structures in the pelagic environment. The
sampling of open water adjacent to structures, as well as the structures themselves,
is critical to increase our understanding. More information is needed on how
structures of all sizes affect fishes at different times of the year and locations.
Methods other than conventional plankton nets are required to explore these
relationships in detail. Finally, for us to determine how important structures are
to fishes, information is also required on the abundance of structures.
ACKNOWLEDGMENTS
I thank H. Choat for discussions on sampling and providing me with unpublished data of Choat
and Kerrigan and A. Alldredge for discussions on marine snow. Thanks to B. Druce, K. Tricklebank,
and B. Gillanders for assistance in the field and laboratory. Funds from the Australian Research
Council supported this research. Helpful comments were provided by M. Atkinson, B. Druce, J.
Govoni, G. Moser, and I. Suthers.
LITERATURE CITED
Ahlstrom, E. H., J. L. Butler and Y. Sumida. 1976. Pelagic stromateoid fishes (Pisces, Perciformes)
of the Eastern Pacific: kinds, distributions, and early life histories and observations on five of
these from the northwest Atlantic. Bull. Mar. Sci. 26: 285-402.
Alldredge, A. L. and C. C. Gotschalk. 1989. Direct observations of the mass flocculations of diatom
blooms: characteristics, settling velocities and formation of diatom aggregates. Deep-Sea Res. 36:
159-171.
-- and M. W. Silver. 1982. Abundance and production rates of floating diatom mats (Rhizo-

KINGSFORD: FISHES, STRUCTURE AND PELAGIC ENVIRONMENT 413
solenia castracanei and R. imbricata var. shrubsolel) in the Eastern Pacific Ocean. Mar. Bot. 66:
83-88.
--- and ---. 1988. Characteristics, dynamics and significance of marine snow. Prog. Oceanog.
20: 41-82.
Andrew, N. L. and B. D. Mapstone. 1987. Sampling and the description of spatial pattern in marine
ecology. Oceanog. Mar. BioI.: Ann. Rev. 25: 39-90.
Bailey, K. M. and E. D. Houde. 1989. Predation on eggs and larvae of marine fishes and the
recruitment problem. Adv. Mar. BioI. 25: 1-83.
Barham, E. G. 1979. Giant 1arvacean houses: observations from deep submersibles. Science 205:
1129-1131.
Blaxter, J. H. S. 1986. Development of sense organs and behaviour of teleost larvae with special
reference to feeding and predator avoidance. Trans. Am. Fish. Soc. 115: 98-114.
--- and L. A. Fuiman. 1990. The role of the sensory systems of herring larvae in evading predatory
fishes. J. Mar. BioI. Assoc. U.K. 70: 413-428.
-- and J. R. Hunter. 1982. The biology of the clupeoid fishes. Adv. Mar. BioI. 20: 1-223.
Boehlert, G. W. 1977. Timing of the surface-to-benthic migrations in juvenile rockfish. Sebastes
diploproa; off southern California. Fish. Bull. U.S. 75: 887-890.
Bottger-Schnack, R. and D. Schnack. 1989. Vertical distribution and population structure of Macrose-
tella gracilis (Copepoda: Harpacticoida) in the Red Sea in relation to the occurrence of Oscillatoria
(Trichodesmium) spp. (Cyanobacteria). Mar. Ecol. Prog. Ser. 52: 17-31.
Choat, J. H. and A. M. Ayling. 1987. The relationship between habitat structure and fish faunas on
New Zealand reefs. J. Exp. Mar. BioI. Ecol. 110: 257-284.
Cushing, D. H. 1975. Marine ecology and fisheries. Cambridge University Press, Oxford. 278 pp.
Dahl, E. 1961. The association between young whiting, Gadus merlangus, and the jelly-fish Cyanea
caillata. Sarsia 3: 47-55.
Damant, G. C. C. 1921. Illumination of plankton. Nature 108: 42-43.
Davenport,
J.
and E. I. S. Rees. 1993. Observations on neuston and floating weed patches in the
Irish Sea. Est. Coast. Shelf Sci. 36: 395-411.
Doherty, P. J. 1987. Light-traps: selective but useful devices for quantifying the distributions and
abundances oflarval fishes. Bull. Mar. Sci. 41: 423-431.
Dooley, J. K. 1972. Fishes associated with the pelagic-Sargassum complex, with a discussion of
the Sargassum community. Contrib. Mar. Sci. 16: 1-32.
Fahay, M. P. 1983. Guide to the early stages of marine fishes occurring in the Western Atlantic
Ocean, Cape Hatteras to the Southern Scoian Shelf.
J.
Northwest Atl. Fish. Sci. 1: 1-423.
Fenchel, T. 1988. Marine plankton food chains. Ann. Rev. Ecol. Syst. 19: 19-38.
Foster, M. S. and D. R. Schiel. 1985. The ecology of giant kelp forests in California: a community
profile. U.S. Fish Wildl. Ser., BioI. Rep. 85 (7.2). 152 pp.
Garcia, J. R. 1990. Population dynamics and production of Phyllorhiza punctata (Cnidaria: Scy-
phozoa) in Laguna Joyuda, Puerto Rico. Mar. EcoI. Prog. Ser. 64: 243-25 I.
Gooding, R. M. and 1. J. Magnuson. 1967. Ecological significance of a drifting object to pelagic
fishes. Pacific Sci. 21: 486-497.
Green, R. H. 1979. Sampling design and statistical methods for environmental biologists. Wiley-
Interscience, New York. 257 pp.
Grondahl, R. and L. Hernroth. 1987. Release and growth of Cyanea caillata (L.) ephyrae in the
Gullmar Fjord, western Sweden. J. Exp. Mar. BioI. Ecol. 106: 91-101.
Hamner, W. M. and D. Schneider. 1986. Regularly spaced rows of medusae in the Bering sea: role
of Langmuir circulation. Limnol. Oceanog. 31: 171-177.
---, R. W. Gilmer and P. P. Hamner. 1982. The physical, chemical and biological characteristics
of stratified, saline, sulphide lake in Palau. Limnol. Oceanog. 27: 896-909.
---, P. P. Hamner and B. S. Obst. 1989. Field observations on the ontogeny of schooling of
Euphausia superba furciliae and its relationship to ice in Antarctic waters. Limnol. Oceanog. 34:
451-456.
--, L. P. Madin, A. L. Alldredge, R. W. Gilmer and P. P. Hamner. 1975. Underwater obser-
vations of gelatinous zooplankton: sampling problems, feeding biology, and behaviour. Limnol.
Oceanogr. 20: 907-91 7.
Haney, J. F. 1988. Die1 patterns of zooplankton behavior. Bull. Mar. Sci. 43: 583-603.
Hay, S.
1.,
J. R. G. Hispol and A. M. Shanks. 1990. North Sea scyphomedusae-summer distribution,
estimated biomass and significance particularly for O-group gadoid fish. Neth. J. Sea Res. 25:
113-130.
Helfman, G. S. 1981. The advantage to fishes of hovering in shade. Copeia 2: 392-400.
Hjort, J. 1914. Fluctuations in the great fisheries of northern Europe viewed in the light of biological
research. Rapp. Reun. Cons. Int. Explor. Mer 20: 1-228.
Holbrook, S. J., R. J. Schmitt and R. F. Ambrose. 1990. Biogenic habitat structure and characteristics
of temperate reef fish assemblages. Aust. J. Ecol. 15: 489-503.

414
BULLETIN OF MARINE SCIENCE, VOL. 53, NO.2, 1993
Houde, E. D. and J. A. Lovdal. 1984. Seasonality of occurrence, foods and food preferences of
ichthyoplankton in Biscayne Bay, Florida. Estuarine, Coastal Shelf Sci. 18: 403-419.
Hunter, J. R. 1981. Feeding ecology and predation of marine fish larvae. Pages 33-79 in R. Lasker,
ed. Marine fish larvae: morphology, ecology, and relation to fisheries. University of Washington
Press, Seattle.
--- and C. T. Mitchell. 1967. Association of fishes with flotsam in the offshore waters of Central
America. Fish. Bull. U.S. 66: 13-29.
--- and ---. 1968. Field experiments on the attraction of pelagic fish to floating objects. J.
Cons. 31: 427-434.
Janssen, 1. and G. R. Harbison. 1981. Fish in salps: the association of squaretails (Tetragonurus
spp.) with pelagic tunicates. J. Mar. BioI. Assoc. U.K. 61: 917-927.
Jones, A. 1981. Overview: rearing and aquaculture. Rapp. Reun. Cons. Int. Explor. Mer 178: 483-
484.
Jones, C. 1986. Determining age oflarval fish with otolith increment technique. Fish. Bull. U.S. 84:
91-103.
Kingsford, M. J. 1988. The early life history of fish in coastal waters of northern New Zealand: a
review. New Zeal. J. Mar. Freshw. Res. 22: 463-479.
---. 1990. Linear oceanographic features: a focus for research on recruitment processes. Aust. J.
Ecol. 15: 27-37.
---. 1992.
Drift algae and small fish in coastal waters of north eastern New Zealand. Mar. Ecol.
Prog. Ser.
--- and 1. H. Choat. 1985. The fauna associated with drift algae captured with a plankton-mesh
purse seine net. Limnol. Oceanog. 30: 618-630.
--- and ---. 1986. Influence of surface slicks on the distribution and onshore movements of
small fish. Mar. BioI. 91: 161-171.
--- and ---. 1989. Horizontal distribution patterns of presettlement fish: are they influenced
by the proximity of reefs? Mar. BioI. 100: 285-297.
--- and M. J. Milicich. 1987. Presettlement phase of Parika scaber (Pisces: Monacanthidae): a
temperate reef fish. Mar. Ecol. Prog. Ser. 36: 65-79.
---, E. Wolanski and J. H. Choat. 1991. Influence of tidally induced fronts and langmuir cir-
culations on distribution and movements of presettlement fishes around a coral reef. Mar. BioI.
106: 167-180.
Ki0rboe, T., K. P. Anderson and H. G. Dam. 1990. Coagulation efficiency and aggregate formation
in marine phytoplankton. Mar. BioI. 107: 235-245.
Kobayashi, D. R. 1989. Fine-scale distribution of larval fishes: patterns and processes adjacent to
coral reefs in Kaneohe Bay, Hawaii. Mar. BioI. 100: 285-293.
Lasker, R. 1974. Field criteria for survival of anchovy larvae: the relation between inshore chorophyll
maximum layers and successful first feeding. Fish. Bull. U.S. 73: 453-463.
---. 1985. An egg production method of estimating spawning biomass of pelagic fish: application
to the northern anchovy, Engraulis mordax. NOAA Tech. Rep. NMFS 36. 99 p.
Legendre, L. and S. Demers. 1984. Towards dynamic biological oceanography and limnology. Can.
J. Fish. Aquat. Sci. 41: 2-19.
Leis, J. M. 1986. Vertical and horizontal distribution offish larvae near coral reefs at Lizard Island,
Great Barrier Reef. Mar. BioI. 90: 505-516.
--- and T. Trnski. 1989. The larvae of Indo-Pacific shorefishes. New South Wales University
Press, Sydney.
Lenanton, R. C. J., A. I. Robertson and J. A. Hansen. 1982. Nearshore accumulations of detached
macrophytes as nursery areas for fish. Mar. Ecol. Prog. Ser. 9: 51-57.
Malej, A. 1989. Behaviour and trophic ecology of the jellyfish Pelagia noctiluca (Forsskal, 1775). J.
Exp. Mar. BioI. Ecol. 126: 259-270.
Mansueti, R. 1963. Symbiotic behaviour between small fishes and jellyfishes, with new data on that
between the stromateid, Peprilus alepidotus, and the Scyphomedusa, Chrysaora quinquecirrha.
Copeia 1963: 40-80.
Marliave, J. B. 1986. Lack of planktonic dispersal of rocky intertidal fish larvae. Trans. Am. Fish.
Soc. 115: 149-154.
Matarese, A.
c.,
A. W. Kendall, Jr., D. M. Blood and B. M. Vinter. 1989. Laboratory guide to early
life history stages of northeast Pacific fishes. NOAA Tech. Rep. NMFS 80. 652 pp.
McCormick, M. I. and J. H. Choat. 1987. Estimating total abundance ofa large temperate-reef fish
using visual strip transects. Mar. BioI. 96: 469-478.
Mitchell, C. T. and J. R. Hunter. 1970. Fishes associated with drifting kelp, Macrocystis pyrifera,
off the coast of southern California and northern Baja California. Calif. Fish Game 56: 288-297.
Moller, H. 1984. Reduction ofa larval herring population by a jellyfish predator. Science 224: 621-
622.

KINGSFORD:ASHES.STRUcrUREANDPELAGICENVIRONMENT 415
Moser, H. G., W. J. Richards, D. M. Cohen, M. P. Fahay, A. W. Kendall, Jr. and S. Richardson.
1984. Ontogeny and systematics of fishes. Am. Soc. Ichthyol. Herpetol. Spec. Publ. no. I. Allen
Press, Inc., Lawrence, Kansas. 760 pp.
Nash, R. D. M., J. J. Magnuson, C. C. Clay and T. K. Stanton. 1987. A synoptic view of the Gulf
Stream Front with 70 kHz sonar: taking advantage ofa closer look. Can. J. Fish. Aquat. Sci. 44:
2022-2024.
Oliver, J. K. and B. L. Willis. 1987. Coral-spawn slicks in the Great Barrier Reef: preliminary
observations. Mar. BioI. 94: 521-529.
Phillips, P. J., W. D. Burke and E. J. Keener. 1969. Observations on the trophic significance of
jellyfishes in Mississippi Sound with quantitative data on the associative behavior of small fishes
with medusae. Trans. Am. Fish. Soc. 98: 703-712.
Prezelin, B. B. and A. L. Alldredge. 1983. Primary production of marine snow during and after an
upwelling event. Limnol. Oceanog. 28: 1156-1167.
Purcell, J. E. 1985. Predation on fish eggs and larvae by pelagic cnidarians and ctenophores. Bull.
Mar. Sci. 37: 739-755.
Richardson, S. L., J. L. Laroche and M. D. Richardson. 1980. Larval fish assemblages and associations
in the north-east Pacific Ocean along the Oregon coast, winter-spring 1972-1975. Estuarine
Coastal Mar. Sci. II: 671-699.
Rountree, R. A. 1990. Community structure of fishes attracted to shallow water fish aggregation
devices off South Carolina, U.S.A. Environ. BioI. Fish. 29: 241-262.
Safran, P. and M. Omori. 1990. Some ecological observations on fishes associated with drifting
seaweed off Tohoku coast, Japan. Mar. BioI. 105: 395-402.
Sainsbury, K. J. 1988. The ecological basis of multi species fisheries, and management ofa demersal
fishery in tropical Australia. Pages 349-382 in J. A. Gulland, ed. Fish population dynamics, 2nd
ed. Wiley, New York.
Saville, A. 1964. Estimation of the abundance of a fish stock from egg and larval surveys. Rapp.
Reun. Cons. Int. Explor. Mer 155: 164-173.
Schiel, D. R. 1985. Growth, survival and reproduction of two species of marine algae at different
densities in natural stands. J. Ecol. 75: 199-217.
Shanks, A. L. 1983. Surface slicks associated with tidally forced internal waves may transport pelagic
larvae of benthic invertebrates and fishes shoreward. Mar. Ecol. Prog. SeT. 13: 311-315.
---. 1987. The onshore transport of an oil spill by internal waves. Science 235: 1198-1200.
Sherman, K., W. Smith, W. S. Morse, M. Berman, J. Green and L. Ejsymont. 1984. Spawning
strategies of fishes in relation to circulation, phytoplankton production, and pulses in zooplankton
off the northeastern United States. Mar. Ecol. Prog. Ser. 18: 1-19.
Silver, M. W., A. L. Shanks and J. D. Trent. 1978. Marine snow: microplankton habitat and source
of small-scale patchiness in pelagic populations. Science 201: 371-373.
Theilacker, G. H. and Y. Watanabe. 1989. Midgut cell height defines nutritional status oflaboratory
raised larval north em anchovy,
Engraulis mordax.
Fish. Bull. U.S. 87: 457-469.
Turner, J. T., P. A. Tester and W. F. Hettler. 1985. Zooplankton feeding ecology: a laboratory study
of predation on fish eggs and larvae by the copepods Anoma/ocara ornata and Centyropages
typicus. Mar. BioI. 90: 1-8.
Underwood, A. J., M. J. Kingsford and N. L. Andrew. 1991. Patterns in shallow subtidal marine
assemblages along the coast of New South Wales. Aust. J. Ecol. 6: 231-249.
Van der Veer, H. W. and W. Oorthuysen. 1985. Abundance, growth and food demand of the
scyphomedusa Aurelia aurita in the Western Wadden sea. Neth. J. Sea Res. 19: 38-44.
Yabe, H. and T. Mori. 1950. An observation on the habit of bonito, Katsuwonus vagans. and yellow
fin, Neothunnus macropterus, school under the drifting timber on the surface of ocean. Bull. Jap.
Soc. Sci. Fish. 16: 35-39.
DATEACCEPTED: April 28, 1993.
ADDRESS: School of Biological Sciences A08. University of Sydney. New South Wales 2006. Australia.