BULLETIN OF MARINE SCIENCE, 69(3): 1089–1094, 2001
ALGAL COLONIZATION OF CARIBBEAN SCORPIONFISHES
David L. Ballantine, J. Nelson Navarro and Dannie A. Hensley
ABSTRACT
Forty algal species (four Cyanophyta, 20 Rhodophyta, three Chlorophyta, three
Phaeophyceae and 10 Bacillariophyceae) are reported as growing on Scorpaena
grandicornis Cuvier and Scorpaena plumieri Bloch from Puerto Rico. A third scorpionfish
species, Scorpaenodes tredecimspinosus (Metzelaar), did not support algal growth. Algae were principally associated with the region of the head and dorsal cirri. Presence of
algae undoubtedly enhances the cryptic camouflage of these fishes.
The phenomenon of algae growing on fish tissue, while unusual, is not rare. Occurrences of algae growing on some freshwater fishes are apparently mostly associated with
superficial wounding. Published accounts of these incidences include that of Nigrelli et
al. (1958) who indicated presence of microscopic algal filaments below the epidermis of
the kissing gourami, Helostoma temmincki Cuvier (ex Kuhl and van Hasselt). The green
filamentous alga Cladophora has also been shown to occur on two Oklahoma freshwater
fish species, Micropterus salmoides (Lacépède) and Ictiobus bubalus (Rafinesque)
(Vinyard, 1953); on carp, Cyprinus carpio Linnaeus (Edwards, 1978), and on the operculum of rainbow trout, Oncorhynchus mykiss (Walbaum) (=Salmo gairdneri Richardson)
(Hoffman, 1967). These occurrences were all considered infections. Growth of two filamentous algal species on lesions over opercular bones in seawater-cultured Tilapia aurea
(Steindachner) have also been seen (Miller and Ballantine, 1972).
Millstein (1998) showed that sloughed skin of the sculpin, Blepsias bilobus Cuvier in
Cuvier and Valenciennes contained large numbers of diatoms. However, most known
occurrences of algae growing on marine fishes are limited to growth on teeth of parrotfishes.
Winn and Bardach (1960) reported conspicuous growths of algae on teeth of large specimens of Scarus guacamaia Cuvier and S. vetula Bloch and Schneider (ex Parra) from
Bermuda. Other records of presence of algae on teeth of Pacific parrotfishes include
those of Isokawa (1956) and Tsuda et al. (1972). The latter identified twelve algal species
on beaks of parrotfishes from Guam.
Scorpionfishes are venomous bottom fishes which exhibit a cryptic mode of life (Böhlke
and Chaplin, 1968). Their coloration and fleshy skin outgrowths mimic the surrounding
habitat in such a way that they are difficult to see (Cott, 1957). Fishelson (1973: 498)
stated that various stonefishes (Synanceiidae) and scorpionfishes (Scorpaenidae) are covered by a “sheet of algae, hydrozoans, diatomeans and other organisms ....” and speculated that this promotes the ability of the fish to blend with its surroundings. Grobecker
(1983) also speculated that in addition to camouflage on stonefish,” Synanceia verrucosa
Bloch and Schneider, presence of algae might serve as an attractant to herbivorous prey.
Beyond indication of presence of filamentous algae and diatoms (Fishelson, 1973), the
fouling organisms were not further identified in these studies. Nagelkerken (1980: 71)
figured an individual of Scorpaena plumieri Bloch that possessed obvious algal growth;
however, he did not further discuss the phenomenon. We report here species of algae
colonizing three species of scorpionfishes in Caribbean western Puerto Rico.
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METHODS AND MATERIALS
Scorpionfishes were collected from coastal waters in western Puerto Rico. Specimens were either collected with a multiprong spear or were coaxed into a diver’s collecting bag. Specimens
were fixed in 10% Formalin/seawater on return to the lab. Lengths of fish specimens were measured as standard lengths (SL) (Hubbs and Lagler, 1949) to the nearest mm using dial calipers.
Pieces of skin were observed with a compound microscope. Diatoms were identified from two of
the S. plumieri specimens. Algal voucher specimens are deposited in the algal herbarium (MSM)
and fish voucher specimens are deposited in the fish museum (UPRM), both of the Department of
Marine Sciences, University of Puerto Rico, Mayagüez, Puerto Rico. Authority designations of
algal taxa are according to Brummitt and Powell (1992).
The following specimens were examined:
Scorpaena grandicornis Cuvier: UPRM 3768, 12.5 cm SL, Lajas, La Parguera, 1.5 km seaward
Media Luna Reef, 17 m; 2.x.1980.
Scorpaena plumieri Bloch: UPRM 3774, 12.0 cm SL, Lajas, La Parguera, inshore cay seaward
of Cueva Island, 1.0 m; 27.xi.1980. UPRM 3770, 13.3 cm SL, Guanica, Ballena Bay, 2.0 m,
30.xii.1980. UPRM 3769, 12.1 cm SL, ibid. 18.v.1981. UPRM 3766, 28.5 cm SL, Lajas, La Parguera,
1.5 km seaward Media Luna Reef, 17 m, 13.v.1981. UPRM 3771, 9.6 cm SL, ibid., 18.viii.1981.
UPRM 3765, 16.0 cm SL, ibid.; 9.ix.1981. UPRM 3775, 24.4 cm SL, Aguadilla, Crash Boat Beach,
9.1 m, 16.iii.1981. UPRM 3767, 13.8 cm SL, Desecho Island, 9.1 m 17.x.1980.
Scorpaenodes tredecimspinosus (Metzelaar): UPRM 3772, 2.7 cm SL, Lajas, La Parguera, edge
of insular shelf, 21 m; 2.iv.1982. UPRM 3773, four specimens (2.2, 2.3, 2.4, 3.0 cm SL), ibid.;
16.iv.1982.
RESULTS
Algal species were most commonly located in the region of the head (Fig. 1) and on
dorsal cirri (Fig. 2); they were less commonly found on sides of the body. Of the five
individuals of S. tredecimspinosus examined, only one specimen bore detectable algae, a
minute amount of the cyanophyte Microcoleus lyngbyaceus. The single specimen of S.
grandicornis bore 14 species of macro algae and seven diatom species. Eight specimens
of S. plumieri were examined. Of these, seven bore substantial amounts of algae, and 33
species were identified on a single specimen.
ALGAL SPECIES IDENTIFIED
CYANOPHYTA
Calothrix crustacea Schousb. & Thur.
Microcoleus lyngbyaceus (Kütz.) P. Crouan & H. Crouan
Oscillatoria lutea C.Agardh
Schizothrix mexicana Gomont
RHODOPHYTA
Aglaothamnion boergesenii (Aponte & D. L. Ballant.) L’Hardy-Halos & Rueness in
Aponte, D. L. Ballant. & J. N. Norris
Aglaothamnion sp.
Acrochaetium sp.
Antithamnionella breviramosa (E. Y. Dawson) E.M.Woll. in Womersley & A. Bailey
BALLENTINE ET AL.: ALGAL COLONIZATION OF CARIBBEAN SCORPIONFISHES
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Figure 1. Epizoic algal growth on head region of Scorpaena plumieri. Algae appear as localized
fuzzy areas (arrowheads). Scale bar = 1.0 cm.
Antithamnionella sp.
Asparagopsis taxiformis (Delile) Trevisan
[Falkenbergia stage]
Centroceras clavulatum (C. Agardh) Mont.
Ceramium fastigiatum Harv. forma flaccidum H. E. Peterson in Børgesen
[C. flaccidum (Kütz.) Ardiss.]
Ceramium sp.
Champia parvula (C. Agardh) Harv.
Chondria sp.
Chroodactylon ornatum (C. Agardh) Basson
Crouania attenuata (C. Agardh) J.Agardh
Diplothamnion jolyi C. Hoek
Erythrotrichia carnea (Dillwyn) J. Agardh
Griffithsia globulifera Harv. ex Kütz.
Herposiphonia secunda (C. Agardh) Ambronn
Heterosiphonia crispella (C. Agardh) M. J. Wynne
Polysiphonia havanensis Mont.
Polysiphonia sp.
Sahlingia subintegra (Rosenv.) Kornmann
Spyridia filamentosa (Wulfen) Harv. in Hooker
Stylonema alsidii (Zanardini) K. M. Drew
HETEROKONTOPHYTA (BACILLARIOPHYCEAE)
Amphora sp.
Cocconeis spp.
Isthmia enervis Ehrenb.
Licmophora ehrenbergii (Kütz.) Grunov
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Figure 2. Algal growth, mostly diatoms on dorsal cirrus of Scorpaena plumieri. Licmophora sp.
(arrowhead) and a sporeling of Ceramium sp. (arrow) are indicated. Scale bar = 250 mm
Licmophora flabellata (Carm.) C. Agardh
Licmophora remulus Grunov
Mastogloia binotata (Grunov) Cleve
Mastogloia schmidtii Heiden
Mastogloia splendida (W. Greg.) Cleve
Tabularia fasciculata (C. Agardh) D. M. Williams & Round
HETEROKONTOPHYTA (PHAEOPHYCEAE)
Dictyota sp.
Hincksia sp.
Sphacelaria sp.
CHLOROPHYTA
Cladophora sp.
Phaeophila dendroides (P. Crouan & H. Crouan) Batters
Rhizoclonium sp.
DISCUSSION
A surprisingly high number of species of macroalgae are able to colonize S. plumieri
and S. grandicornis. A total of 40 species of fouling algae (30 spp. macroalgae, with
representatives from all major groups, and 10 spp. diatoms) were found growing on S.
plumieri and S. grandicornis. An unidentified hydroid species was found as well. Not all
of the macroalgal species were unidentifiable to species as they were frequently repre-
BALLENTINE ET AL.: ALGAL COLONIZATION OF CARIBBEAN SCORPIONFISHES
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sented by sporelings. The Cyanophyta species Oscillatoria lutea and M. lyngbyaceus
were present on 44.4 and 55.6% of the S. plumieri examined. Two of the Rhodophyta
species, Stylonema alsidii (55.6%) and Erythrotrichia carnea (66.7%), were also commonly present on scorpionfishes. Acrochaetium sp. and Ceramium spp. were the other
most common algal species present. While cover of algal growth was not quantified, the
amount of algae on the scorpion fishes was inconsistent, varying from a few sparsely
colonizing individuals to a conspicuous cover.
Typical fish epithelial cells produce a mucopolysaccharide layer (Ellis et al., 1989) and
an outer glycoprotein mucous layer (Mittal and Banerjee, 1980). Dawson (1959) stated
that the normal mucous covering of fishes is inhibitory to either the growth or settlement
of invading species. Hence, an injury which disrupts this covering could conceivably
allow the recruitment of algal spores as is seen in the colonization of algae on freshwater
fish species. Few fishes, however, have keratinized epidermal cells (Mittal and Banerjee,
1980). Fishelson (1973) indicated that the keratinized epidermal cells of stonefish were
colonized by fouling organisms including algae. Fishelson (1973) also observed presence
of keratinization in two Red Sea scorpionfishes; however, it was less than in the stonefish.
There is some uncertainty as to whether tropical west Atlantic scorpionfishes possess
keratinized epithelial cells or whether skin sloughing occurs. The possibility that skin
characteristics differ on different body parts is indicated by the fact that algal colonization was extremely limited away from the head region. Skin sloughing, similar to that
reported by Fishelson (1973) and Millstein (1998), may explain why one of the larger S.
plumieri specimens examined was devoid of algal growth altogether. The fact that the
skin of S. plumieri and S. grandicornis is typically colonized by algae undoubtedly abets
the camouflage exhibited by these two species. S. tredecimspinosus may have different
skin characteristics which explains its lack of being colonized by algae.
ACKNOWLEDGMENTS
We thank E. Williams and J. Kimmel who assisted in collecting. We also thank J. Randall for
discussion of fouling on Scorpaenidae.
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DATE RECEIVED: May 12, 2000.
DATE ACCEPTED: June 22, 2001.
ADDRESSES: (D.L.B., D.A.H.) Department of Marine Sciences, P.O. Box 9013, University of Puerto
Rico, Mayagüez, Puerto Rico 00681; (J.N.N.) Biology Department, Pontifical Catholic University of
Puerto Rico, Ponce, Puerto Rico 00731.