Differential growth of the barnacle Notobalanus flosculus (Archaeobalanidae) onto artificial and live substrates in the Beagle Channel, Argentina.

LEONARDO VENERUS,; JAVIER CALCAGNO,; GUSTAVO ALEJANDRO LOVRICH; DANIEL NAHABEDIAN,

Helgoland Marine Research

Año: 2005 vol. 59 p. 196 - 205

Abstract In the Beagle Channel, southern SouthAmerica (ca. 55S 67W), about 20% of false king crabs(Paralomis granulosa) >80 mm carapace length are fouledwith the barnacle Notobalanus flosculus. To evaluatedifferences in growth rates of barnacles attached toartificial and live substrates, clay tiles were anchored ascollectors to the bottom at two different sites in theBeagle Channel in September 1996: in Ushuaia harbour(low currents and high levels of suspended matter) andaround the Bridges Islands (strong currents and low levelof suspended matter). Another set of collectors wasdeployed at the same sites in October 1998 to collectbarnacles for histological studies. Tiles were removedfrom each place, approximately, on a monthly basis.Carapaces of P. granulosa with the epizoic N. flosculuswere sampled between November 1996 and 1997, andbetween March 1998 and September 1999, to studysexual maturation of barnacles. Growth of barnacleswas compared between the collectors and P. granulosacarapaces following a qualitative approach. A sexualmaturity scale was defined, based on the stage ofdevelopment of the female reproductive apparatus ofN. flosculus. Growth rate of barnacles was highest in theharbour, intermediate on P. granulosa, and lowestaround the Bridges Islands. Presence of oocytes wasregistered only in epizoic barnacles, suggesting that atleast a proportion of these individuals is able to spawnon the carapaces. The potential advantages of settling ona living substrate, namely increased availability of foodparticles and decreased predation risks are discussed.