Changes and drivers of freshwater mussel diversity and distribution in northern Borneo

Human activities are threatening Borneo's unique biodiversity, but little is known on the status of freshwater invertebrates. We assessed changes in diversity and distribution of freshwater mussels (Bivalvia: Unionida) in northern Borneo, and identified drivers of present distribution and threats. Past distribution data were collected from literature and museum resources. Present distribution data were collected from 21 river basins, and 47 water quality, climatic, landscape and human variables explored as potential predictors of species presence/absence. Species delimitations were identified by morphology and COI barcoding, and haplotype networks generated. Our data indicate that over the past 50 years, four of originally five native species have become very rare or possibly locally extirpated. Since these four species are endemic to Borneo, other Bornean river basins should urgently be surveyed to identify any remaining populations. In the same time span, the non-native Sinanodonta woodiana has become the most widespread freshwater mussel in northern Borneo. The fifth native species was identified as Rectidens sumatrensis and found in four Sarawakian river basins, thus contradicting previous assumptions of an endemic Bornean Rectidens species. Although a number of stable R. sumatrensis populations are retained across Sarawak, the species' strong spatial contraction in mainland Sundaland and apparent low tolerance to eutrophication suggest that it is vulnerable to further habitat alteration. Our results indicate that Borneo's (endemic) freshwater invertebrate biodiversity is declining rapidly. Comprehensive surveys targeting an array of invertebrate and vertebrate taxa are needed to identify Borneo's freshwater biodiversity hotspots, where conservation efforts should be concentrated

Comparison of avifauna diversity between forested area and different plots of oil palm plantation area in Bau, Sarawak

Avifauna surveys were carried out in the forest within the SALCRA Jagoi oil palm estate, Bau, Sarawak in April 2015. The main objective of the study was to compare the species diversity between the forested area with the 5-year and 15-year plots in oil palm plantation area. Ten mist nets were deployed within the forest starting from 0600 hours to 1800 hours daily. A total of 25 individuals of birds representing seven species from five families were recorded in the forested area; while there were 30 individuals of birds representing 12 species from nine families documented in the different plots of oil palm plantation area. The most dominant species netted in the forested area was Little Spiderhunter or Arachnothera longirostra with 44% relative abundance. The result showed that there was a significant difference between the diversity of birds in forested area and the 5-year plot, but not between forested area and the 15-year plot. The diversity in the forested area was higher than the 15-year plot, however was lower than the 5-year plot

Development of Bacillus strain B12 and B45 as putative probiotics to improve growth and survival of Epinephelus fuscoguttatus (Forsskal, 1775) juvenile challenged with vibrio alginolyticus

Occurrences of bacterial diseases and the overexploitation to overcome it have resulted to the emergence of antibiotic resistant microorganisms. In relation to this matter,experiments were performed in this study by identifying putative probionts, screening of putative probionts against selected pathogenic strains based on their in vitro antagonism activities, in vivo safety test, feeding trial of E. fuscoguttatus juveniles and challenge with V. alginolyticus. Gram’s method had classified 44 bacterial strains as rod, gram positive cells while biochemical test (BBL CrystalTM identification system) had identified 44 bacterial strains to species level. From 44 bacterial strains, 22 were non-haemolytic isolates. Agar well diffusion assay have demonstrated two bacilli strains; B12 and B45 elucidating intermediate (++; 11 mm – 15 mm) to highest level (+++; >16 mm) of inhibition zones against Vibrio alginolyticus, V. parahaemolyticus,V. harveyi and Aeromonas hydrophila. The broth culture assay in this study observed a complete inhibitory activity of Bacillusstrain B12 towards V. alginolyticus at preincubation cell density of 105 and 107 cfu/mL while Bacillus strain B45 have displayed no inhibitory activity. 16S rRNA gene sequencing have identified Bacillus strain B12 as Bacillus amyloliquafaciens (94% similarity) and Bacillusstrain B45 as Bacillus subtilis (95% similarity). Pathogenicity test of Bacillus strain B12 and B45 by intraperitoneal (IP) injection have revealed no sort of abnormalities or mortalities on E. fuscoguttatus juveniles. Supplementation of Bacillus strain B12 into feed of E.fuscoguttatus juveniles showed an efficient feed conversion ratio (FCR) of 1.17 + 0.07, increased specific growth rate (2.66 + 0.23) and survival (98 + 1.73%). Application of Bacillus strain B12 into daily feed had significantly increased survival (P<0.05) to 71.65% when E. fuscoguttatus juveniles were challenged with V. alginolyticus. To summarize, experimental findings in this study showed that Bacillus strain B12 at cell density of 107 cfu/mL have the potential to be used as feed additive to improve growth and survival of E. fuscoguttatus juveniles

Development and evaluation of hotshot protocols for cost-and time-effective extraction of PCR-ready DNA from single freshwater mussel larvae (Bivalvia: Unionida)

Freshwater mussels (Unionida) are unique in that their larvae (glochidium, haustorium or lasidium) parasitize vertebrate hosts, with a given mussel species metamorphosing only on a limited array of host species (Wächtler, Mansur & Richter, 2001). Collecting data on host fish identities is important for both conservation and commercial applications, but requires identification of single larvae to species level. This is most efficiently achieved by molecular species identification (White, McPheron & Stauffer, 1996; Kneeland & Rhymer, 2007, 2008; Boyer et al., 2011; Zieritz et al., 2012; Vannarattanarat et al., 2014), because morphological identification of larval mussels is time-consuming and sometimes unreliable (Wiles, 1975; O’brien, Williams & Hoggarth, 2003)