Distribution and Captive Breeding of Barnacle: A Potential Live-Feed for Enhancement Blue Economy

Abstract

Barnacles (Cirripedia: Thecostraca) are sessile marine crustaceans with vital ecological and economic significance across global coastal ecosystems, yet their diversity, biology, and aquaculture potential remain unstudied in Bangladesh. The first integrative investigation into the morphological identification, spatial distribution, reproductive biology of acorn barnacles along the seven intertidal zones- Chowfaldandi (CD), Dorianagor (DN), Raju Khal (RJ), Inani (IN), Paturtek (PT), Teknaf (TC), and Sha Porir Dwip (SP) with upper and lower strata along the southeastern coast of Bangladesh was done. Additionally, it reports the first feeding trial comparing barnacle nauplii (BN) and barnacle meat (BM) with polychaetes (PO), Artemia (AN), and commercial feed (CF), tested on both tilapia (Oreochromis mossambicus) fry and shrimp (Litopenaeus vannamei) post-larvae, to evaluate their potential as larval feed for marine fish and crustaceans. Twelve acorn barnacle species from three families and six subfamilies were identified across seven intertidal sites, with distribution patterns strongly influenced by tidal strata, substrate type, and local habitat characteristics. The coastline predominantly comprised sandy habitats. In the upper stratum, the highest mean density in 15×15 cm2 sampling site was recorded at IN (2085.4 ± 1161.8), while the highest mortality occurred at PT (389.1 ± 312). In the lower stratum, IN and SP exhibited the highest barnacle densities, although IN also reported the greatest mortality. Moreover, barnacle attachment was markedly higher on artificial substrates, particularly on concrete (1373.08 ± 1031.6), compared to both natural (stone, mollusk shell and mangrove) and other artificial surfaces (wood, bamboo, and plastic). Species such as Amphibalanus amphitrite and Chthamalus moro were widespread, while others like commercial Austromegabalanus psittacusfrom PT and Tetraclita squamosafrom IN showed localized occurrence, highlighting potential biogeographic and ecological specificity. Moreover, the genera Amphibalanus and Chthamalus were the most dominant. Morphometric analyses of most abundant A. amphitrite revealed a strong relationship between width of basis (WB) and length of basis (LB)(R² = 0.8786, p<0.01). Length–weight regression models indicated highly significant allometric relationships, with xii barnacle weight (WT) basis length (R² = 0.8983) and basis width (R² = 0.8884). The embryo fecundity of A. amphitrite barnacles (basal length: 0.801 ± 0.356 cm) was 6,359 ± 2,160 embryos per individual. This species has a year-round mature gonadal activity and embryo stage-4h (ready to release), with peak development during pre-monsoon to monsoon months. After successful induced breeding of barnacle, nauplii were reared in hatchery conditions using microalgae cultured in cost-effective media. Nauplii containing six planktonic stages (stage-Ⅰ to stage-Ⅵ) prior to settlement, lasted for 13 days. On 30 days feeding trial, Oreochromis mossambicus fry fed with where BN exhibited significantly higher growth across multiple metrics, including final length, final weight, net weight gain, daily weight gain, percent weight gain, and specific growth rate compared to AN fed and CF feed fry. The CF group consistently showed the lowest performance, while Artemia-fed fry showed moderate growth for those growth parameters, with no statistically significant variation in condition factor and survival. The 30-day feeding trial on Litopenaeus vannamei post-larvae, BM diet also showed significantly higher (p<0.001) growth (total length, total weight, muscle weight, head weight, and head length ) and survival than other diets. . Successful induced breeding and hatchery rearing of Amphibalanus naupliiand their demonstrated efficacy as live feed in finfish and shrimp trials highlight barnacles as a promising alternative feed source in aquaculture. This research not only fills a major knowledge gap in Bangladesh’s marine invertebrate biology but also offer insights for advancing sustainable aquaculture, optimizing hatchery inputs, and enhancing blue economy of Bangladesh through underutilized marine invertebrates.