Feeding and reproductive biology of Saurida undosquamis (Richardson, 1848) from Parangipettai coast, Southeast coast of India.
The feeding biology, spawning season, size at first maturity, sex ratio and fecundity of the commercially important lizardfish (Saurida undosquamis) were studied in Parangipettai waters of the southeast coast of India. Fishes formed the predominant food item. Diversity of the prey items showed maximum value (H'log 2-3.61 +/- 0.11) during the postmonsoon season and minimum during the monsoon season (2.89 +/- 0.17). The richness (1-lambda') also showed a similar trend and varied from 0.81 +/- 0.13 (monsoon) to 0.91 +/- 0.01 (postmonsoon). The size at first maturity (50% incidence of mature fish) was 195 mm. But when the size at first maturity was calculated by adjusting the proportion of maturity percentages, the maturity size was found to be 140 mm. This method is advantageous from the point of view of fisheries management as this species can be exploited above 140 mm rather than above 195 mm. The gastrosomatic index was found maximum during postmonsoon and minimum during the monsoon season showing the inverse relationship between feeding and spawning. This species was found to spawn from August to January with a peak in November. The fecundity ranged from 19, 856 in a fish measuring from 20.1 cm in length (97 g) to 79,282 in a fish of 29 cm (290 g). The overall sex ratio (1:1.19) was found to deviate significantly from the expected 1:1 ratio. (chi2 = 19.1, p < 0.005). Month- wise, it conformed to the expected 1:1 ratio during most of the months except January, June, September, November and December. Higher gonado-somatic index values observed during October-December suggested spawning activity during this period. This species is found to a total spawner in the Parangipettai waters.
Parasitic fauna of the marine greater lizard fish Saurida undosquamis (Richardson, 1848)
Through examination of 125 specimens of the marine greater lizard fish Saurida undosquamis (Richardson, 1848) obtained from Zagazig fish market and its source from Gulf of Suez, the overall prevalence was 44.8%. The parasitic fauna was composed of Acanthocephala; Serrasentis sagittifer (prevalence: 12.8%), Cestoda; Oncodiscus sauridae (prevalence: 5.6%), Nematoda; Echinocephalus species larvae (prevalence: 4%), female of Philometra species (prevalence: 13.6%) and Trematoda; Lecithochirium grandiporum (prevalence: 16%) and juvenile didymozoid; Neotorticaecum (prevalence: 2.4%). The most prevalent parasitic fauna was nematodes followed by trematodes then acanthocephala and cestodes. The detected parasitic fauna was morphologically described by light microscope.
Palaeomicrobiology: current issues and perspectives
Palaeomicrobiology is an emerging field that is devoted to the detection, identification and characterization of microorganisms in ancient remains. Data indicate that host-associated microbial DNA can survive for almost 20,000 years, and environmental bacterial DNA preserved in permafrost samples has been dated to 400,000–600,000 years. In addition to frozen and mummified soft tissues, bone and dental pulp can also be used to search for microbial pathogens. Various techniques, including microscopy and immunodetection, can be used in palaeomicrobiology, but most data have been obtained using PCR-based molecular techniques. Infections caused by bacteria, viruses and parasites have all been diagnosed using palaeomicrobiological techniques. Additionally, molecular typing of ancient pathogens could help to reconstruct the epidemiology of past epidemics and could feed into current models of emerging infections, therefore contributing to the development of appropriate preventative measures.