Effects of Macrofaunal Recolonization on Biogeochemical Processes and Microbiota—A Mesocosm Study

Macroinvertebrates are widespread in lake sediments and alter sedimentary properties through their activity (bioturbation). Understanding the interactions between bioturbation and sediment properties is important given that lakes are important sinks and sources of carbon and nutrients. We studied the biogeochemical impact of macrofauna on surface sediments in 3-month-long mesocosm experiments conducted using sediment cores from a hypoxic, macrofauna-free lake basin. Experimental units consisted of hypoxic controls, oxic treatments, and oxic treatments that were experimentally colonized with chironomid larvae or tubificid worms. Overall, the presence of O2 in bottom water had the strongest geochemical effect and led to oxidation of sediments down to 2 cm depth. Relative to macrofauna-free oxic treatments, chironomid larvae increased sediment pore water concentrations of nitrate and sulfate and lowered porewater concentrations of reduced metals (Fe2+, Mn2+), presumably by burrow ventilation, whereas tubificid worms increased the redox potential, possibly through sediment reworking. Microbial communities were very similar across oxic treatments; however, the fractions of α-, β-, and γ-Proteobacteria and Sphingobacteriia increased, whereas those of Actinobacteria, Planctomycetes, and Omnitrophica decreased compared to hypoxic controls. Sediment microbial communities were, moreover, distinct from those of macrofaunal tubes or feces. We suggest that, under the conditions studied, bottom water oxygenation has a stronger biogeochemical impact on lacustrine surface sediments than macrofaunal bioturbation.

Effects of Wetting Media Cattle Blood, Rice Gruel and Water on the Yield and Amino Acid Composition of Tubificid Worms

The effects of three wetting media (cattle blood, rice gruel and subsurface clean water) of the culture media ingredients (a mixture of mustard oil cake, soybean meal and mud) on the yield and amino acid composition of tubificid worms cultured on a pilot scale in a fish farm for 42 days were evaluated. The worm yields were in the order: cattle blood wetted media (683.68 ± 3.86 mg/cm2), rice gruel (615.63 ± 3.66 mg/cm2), water (584. 38 ± 1.41 mg/cm2). Lysine, arginine and leucine were the most prevalent of the eight essential amino acids in worms cultured in the media wetted in cattle blood medium. The results suggested that a mixture of 40% mustard oil cake, 30% soybean meal and 30% mud can be used for the commercial culture of tubificid worms as live fish food. The tubificid worms showed high level of amino acids suitable for fish that require a high content of dietary amino acids. Asiat. Soc. Bangladesh, Sci. 45(2): 229-239, December 2019

Impact of live tubificid worms on the growth and survival of Heteropneustes fossilis (Bloch, 1794) reared in tanks

An experiment was conducted on growth, survival and flesh quality of fingerlings of stinging catfish, Heteropneustes fossilis (Bloch, 1794) were evaluated using three types of feeds namely live tubificid worm, tubificid powder and commercial pellet feed. Three feeds were used in three treatments where Treatment-T1with pellet feed (control), Treatment-T2 with tubificid powder and Treatment-T3 having live tubificid worms. Twenty fingerlings (8.04 ± 0.01 g) were released in each 50 L tank for 45 days rearing. The fishes were fed twice a day at 10% of body weight for first 15 days and that of 8% per day for the next 30 days. Sampling was conducted fortnightly. Significant higher mean weight 48.53 ± 1.13 g was observed in stinging catfish at the 45th day fed with live tubificid worms than those of others (P<0.05). The highest survival rate was 83.33±4.41%, average daily gain 0.90 ± 0.03 g day-1, specific growth rate 3.99 ± 0.05%, food conversion ratio 1.65 ± 0.10 and protein content 17.48 ± 0.28% were found at the 45th day of treatment T3 when live tubificid worms were used as feed. Live tubificid worms can be used as a good alternative to commercial feed in rearing of stinging catfish.Bangladesh J. Sci. Ind. Res. 51(3), 175-182, 2016

Identification of genera of tubificid worms in Bangladesh through morphological study

Tubificids are aquatic oligochaete worms (F- Naididae, O- Haplotaxida, P- Annelida) distributed all over the world. The worms are very important as they are used as live food for fish and other aquatic invertebrates. A step was taken to identify the genera of tubicifid worms that exist in Mymensingh district, Bangladesh on the basis of some external features including the shape of their anterior (prostomium) and posterior end, number of body segment and arrangement of setae. The study result indicated the existence of three genera among the tubificid worms. These were Tubifex, Limnodrilus and Aulodrilus. All these three genera possessed a cylindrical body with a bilateral symmetry formed by a series of metameres. The number of body segments ranged from 34 to 120 in Tubifex, 50 to 87 in Limnodrilus, and 35 to 100 in Aulodrilus. In Tubifex, the first segment, with the prostomium, was round or triangular bearing appendages, whereas, in Limnodrilus and Aulodrilus, the prostomium without appendages was triangular and conical, respectively. Three types of setae i.e., hair setae, pectinate setae and bifid setae of various sizes were found in Tubifex, whereas, Limnodrilus possessed pectinate setae and bifid setae of more or less similar size and shape; and Aulodrilus possessed only hair setae and bifid setae of different size.Asian J. Med. Biol. Res. March 2016, 2(1): 27-32

Checklist of Aquatic Oligochaetes Species in Tigris–Euphrates River basin

A total of 60 species of aquatic oligochaetes were identified in different sites within Tigris-Euphrates basin / Iraq, including River Tigris, River Euphrates, Southern marshes ( Al-Haweiza , Al-Hammar and Al-Chebaiesh ) , Shutt Al-Germa, and Shatt Al-Arab. In River Euphrates 39 species were identified, 40 species from River Tigris and 32 species from Shatt-Al-Arab and southern marshes.The identified species were classified as four species of Family Aeolosomatidae, 54 species of Naididae ( 31 Naidinae , 8 Pristininae and 15 Tubificid worms), one species of each of Lumbriculidae ( Lumbriculus variegates ) and Lumbricidae ( Eiseiella tetraedra). Among Aeolosomatidae , Aelosoma aquaternarium, A. Liedyi, A. variegatum and A. hemprichi, in which, A. variegatum was the most frequent species, found in Euphrates river. Naidinae community were represented by five species of genus Chaetogaster, two species of each of Paranais, Slavina, & Stylaria, four species of Allonais , and seven species of each of Dero and Nais, in addition to Stephensoniana trivandrana, Specaria josinae and Ophidonais serpentina. Nais variabilis was the most abundant and frequent species in River Tigris while Stylaria lacustris & Ophidonais serpentina are abundant in River Euphrates . Species of Pristininae were representative by four species of genus Pristina and three species of genus pristinella, among them Priatina longiseta is the most abundant species.Tubificid worms, Branchuira sowerbyi and Limnodrilus hoffmeisteri were the most frequent and abundant species in the surface sediments of Iraqi waters. Beside L. hoffmeisteri , other five species of Limnodrilus, two species of Potomothrix, and a single species of Tubifex tubifex , Embolocephalus velutinus, Aulodrilus piguetia, Psammoryctides moravicus and Rhyacodrilus coccineus were recorded.