Population structure of the lancelet Branchiostoma caribaeum (Cephalochordata: Branchiostomidae) in the Baía de Guanabara, Rio de Janeiro, southeastern Brazil

Abstract

Population structure of the lancelet Branchiostoma caribaeum Sandevall, 1853 was studied in four surveys, corresponding to austral seasons, in a tropical bay, southeast of Brazil. Abundance was higher in the spring and was positively correlated to coarse sediments, limiting its occurrence to some sectors of the sampling area. Body length and biomass differed seasonally but not between sexes. Sexually mature individuals occurred in all seasons, suggesting continuous breeding that is typical of tropical species. Variation in the frequency of small specimens indicates temporal differences in the intensity of breeding. The body length of recruits differed from other population of lancelets and the small length which B. caribaeum attained sexual maturity in Guanabara Bay may be related to local environmental stress or the great availability of food.

On Branchiostoma californiense (Cephalochordata)from the Gulf of Nicoya estuary, Costa Rica

“…For B. nigeriense, Webb & Hill (1958) found experimentaly that a salinity of 13‰ was the lowest tolerated by larvae and also mention previous work on B. belcheri that lives on a salinity range of 19 to 29‰. The presence of high densities of B. caribaeum in an eutrophic bay, receiving discharges from industrial and domestic sources, has been reported by Da Silva et al (2008). The Gulf of Nicoya estuary receives agricultural, industrial and domestic discharges (Vargas & Mata 2004), mainly by the Tempisque and Tárcoles rivers (Fig.…”

“…In these sediments the organisms usually show a patchy distribution, being abundant at one spot and absent from another a few centimeters away (Webb 1975). Although often viewed as occurring in clean coarse sediments, lancelets have also been reported from anthropologically impacted sediments (Da Silva et al 2008). According to Ruppert et al (2000), these organisms feed on particles smaller than 100 microns (microbial and phytoplankton production), and transfer this production to higher trophic levels.…”

“…Their larval phase may last for several months, allowing the organisms to be transported by currents to distant habitats (Webb 1975). Length at recruitment is known for several species, ranging from 3.3 to 7.0mm (Da Silva et al 2008). The Pacific species, B. belcheri reaches sexual maturity at a length greater than 20mm, and most individuals mature after their second year (Yamaguchi & Henmi 2003).…”

Population dynamics of the amphioxus Branchiostoma elongatum from northern Chile

“…About 30 species widely distributed in coastal waters all around the world have been described, comprising two families and three genera (Chen, 2007; Anaya, 2010). However, studies dealing with population ecology are restricted to a few species within the genus Branchiostoma , including B. belcheri and B. malayanum in China, Japan and Hong Kong (Henmi & Yamaguchi, 2003; Chen et al , 2008), B. lanceolatum in the North Sea and the Mediterranean (Courtney, 1975), B. senegalense and B. nigeriense in north-west Africa (Webb, 1958; Gosselck & Spittler, 1979), B. floridae in the USA (Stokes & Holland, 1996) and B. caribaeum in Jamaica and southern Brasil (McShine, 1971; da Silva et al , 2008). Lancelets inhabit a variety of coastal habitats including estuaries, coastal lagoons, open coasts and river deltas, with population abundances displaying huge differences, ranging between 10 and 9000 ind m −2 (Gosselck, 1975; Chen, 2007; Laudien et al , 2007), but little is known about their role in these habitats.…”

First Record of Amphioxus Branchiostoma californiense (Amphioxiformes: Branchiostomatidae) Adjacent to a Shallow Submarine Hydrothermal System at Banderas Bay (Mexico)

“…The cephalochordates are cosmopolitan and usually inhabit the shallow marine waters near the coasts [1,7], although some species can inhabit depths greater than 200 m. The work of Kon, et al [8] established that they can spend most of their lives forming part of the plankton [4,9,10]. They are mainly associated with thick sediments, such as sand, gravel, or shells' remains [9,11]. These animals are dioecious and without apparent sexual dimorphism [1], and their larvae can be benthic or planktonic [3,6,12].…”