Species Description: The chain pipefish, Syngnathus louisianae, is a member of the family Syngnathidae. The IRL contains a few members of this group, including five other pipefishes and three seahorse species.
Syngnathids are characterized by a body divided into tail and trunk portions, and a head with a prominent snout (Robins & Ray 1986). The length of this snout is one of the main factors used to cluster pipefishes into three groups.
The chain pipefish is a long-snout species, with a head-to-snout ratio of less than 1.9 (Robins & Ray 1986). The common name of the species is derived from the long row of chainlike diamond-shaped marks along the lower side. The dorsal fin of syngnathids is usually aligned with tail and trunk rings. In S. louisianae, the fin is located between the 2nd and 3rd trunk ring, extending up to the 6th tail ring some individuals (Dawson 1972). Other fin ray and meristic counts are as follows: dorsal fin rays = 33-36; trunk rings = 19-21; and tail rings = 36-37 (Robins & Ray 1986).
Potentially Misidentified Species: As mentioned previously, five other pipefishes are found in the IRL. Of these, one is a long-snout species like S. louisianae. The dusky pipefish, S. floridae, is generally smaller than S. louisianae, at a maximum length of 25 cm (Robins & Ray 1986). The body is olive-brown and variably mottled without distinct bands. The dorsal fin is usually located from the 2nd trunk ring to the 4th or 5th tail ring. Other fin ray and meristic counts are as follows: dorsal fin rays = 26-34; trunk rings = 17-18; and tail rings = 30-38 (Robins & Ray 1986). The commonly seen gulf pipefish, S. scovelli, is a short-snout species only reaching 7.5 cm in length.
Regional Occurrence & Habitat Preference: The range of the chain pipefish extends from Virginia to the Caribbean coast of Mexico, Jamaica, Bermuda, and the Gulf of Mexico. However, this species is reported to be absent from the Bahamas (Robins & Ray 1986). Most populations of S. louisianae inhabit seagrass beds, marsh areas (Kanouse et al. 2006) and floating mats of the brown algae Sargassum natans and S. fluitans (Wells & Rooker 2004).
IRL Distribution: The chain pipefish can be found throughout the IRL, usually in association with seagrass beds and drift algae.
Age, Size, Lifespan: Little information exists on the maximum age and average lifespan of S. louisianae. The maximum reported length for the chain pipefish is 38 cm (Monteiro et al. 2005, Robins & Ray 1986), but most specimens collected in the field measure between 2.8 and 10 cm (Dawson 1972).
Abundance: The highest abundance for the chain pipefish occurs in Florida during the summer months of May to July (Dawson 1972, Kanouse et al. 2006, Wells & Rooker 2004). Few density estimates exist for S. louisianae, but the total catch for populations inhabiting Sargassum mats in the northern Gulf of Mexico was approximately 2,000 individuals (Wells & Rooker 2004).
Reproduction: Like most other syngnathids, S. louisianae males give birth to live young from eggs transferred from the female to a specialized marsupium called a brood pouch. Unlike most seahorses, pipefishes of the genus Syngnathus incubate eggs in an inverted pouch (Monteiro et al. 2005). Fertilization occurs after the female transfers the eggs, and incubation lasts until embryos develop into juveniles. Studies suggest that reproduction peaks in late spring and early summer for populations in Florida, with a large abundance of juveniles found in the waters of the Gulf of Mexico in August (Wells & Rooker 2004). Information on maturation age and size is scarce, but the largest reported length for the chain pipefish (38 cm) was for a pregnant male (Monteiro et al. 2005).
Embryology: Compared to other syngnathids, the embryology and development of S. louisianae is poorly documented. The maximum number of eggs reported for a single male was 900, each measuring approximately 0.8 mm in diameter (Monteiro et al. 2005).
Temperature & Salinity: The habitat and distribution of the chain pipefish suggests that it has large salinity and temperature tolerances, although most individuals are found in warm coastal waters. Salinity and temperature ranges for populations in the Gulf of Mexico off the Mississippi coast range from 13.1 to 36.5 ppt and 12.4 to 30.8°C (Dawson 1972).
Trophic Mode: Like other syngnathids, chain pipefish prey mostly on small crustaceans such as shrimps, amphipods and crabs.
Predators: Little information exists about predators of the chain pipefish, but the ability of the species to camouflage itself between seagrass blades and among clumps of algae reduces predation. Still, individuals are likely preyed upon by other fishes and birds.
Associated Species: No known obligate associations exist for S. louisianae. However, chain pipefish are associated with several organisms common to seagrass beds and drift algae communities. In Sargassum mats, S. louisianae can be found alongside a variety of other invertebrates and fishes, including: sargassumfish, Histrio histrio; sergeant majors, Abudefduf saxatilis; blue runners, Caranx crysos; gray triggerfish, Balistes capriscus; planehead filefish, Monacanthus hispidus; and greater amberjack, Seriola dumerili (Wells & Rooker 2004).
References: Dawson, CE. 1972. Nektonic pipefishes (Syngnathidae) from the Gulf of Mexico off Mississippi. Copeia. 1972: 844-848.
Herald, ES. 1942. Three new pipefishes from the Atlantic coast of North and South America with a key to the Atlantic American species. Stanford Ichthyol. Bull. 2: 125-134.
Hildebrand, HH. 1954. A study of the brown shrimp (Penaeus aztecus Ives) grounds in the western Gulf of Mexico. Publ. Ist. Mar. Sci. Univ. Texas. 3: 233-366.
Hildebrand, HH. 1955. A study of the fauna of the pink shrimp (Penaeus duorarum Burkenroad) grounds in the Gulf of Campeche. Publ. Ist. Mar. Sci. Univ. Texas. 4: 169-232.
Joseph, EB & RW Yerger. 1956. The fishes of Alligator Harbor, Florida, with notes on their natural history. Florida State Univ. Stud. 22: 111-156.
Kanouse, S, La Peyre, MK & JA Nyman. 2006. Nekton use of Ruppia maritima and non-vegetated bottom habitat types within brackish marsh ponds. Mar. Ecol. Prog. Ser. 327: 61-69.
Monteiro, NM, Almada, VC & MN Vieira. 2005. Implications of different brood pouch structures in syngnathid reproduction. J. Mar. Biol. Ass. UK. 85: 1235-1241.
Robins, CR & GC Ray. 1986. A field guide to Atlantic coast fishes of North America. Houghton Mifflin Co. New York. USA. 354 pp.
Wells, RJD & JR Rooker. 2004. Spatial and temporal patterns of habitat use by fishes associated with Sargassum mats in the northwestern Gulf of Mexico. Bull. Mar. Sci. 74: 81-99.