பயோடைவர்சிட்டி & அழிந்து வரும் உயிரினங்களின் இதழ்

Bangladesh is traversed by numerous rivers and it comprises most of the delta of three great rivers- the Ganges, the Brahmaputra and the Meghna. Specifically, the greater part of northeast region is taken up by the wetland basin and is characterized by the presence of numerous large, deeply flooded depressions, known as haors, between the rivers where Hakaluki haor is one of them. A study was conducted using the soil and landform information of 1985 and 2003 of Hakaluki haor wetland ecosystem. Areas of soil boundaries between 1985 and 2003 were estimated using polygon attribute tables (PAT) files which revealed that this wetland ecosystem has been decreasing at an alarming rate due to sedimentation from the surrounding hilly areas. These estimates were verified using the land type information because soil boundaries and land types are the inter-related issues. Besides, a soil profile study also revealed that a buried horizon formed beneath the plow layer which signifies the sedimentation. Thus, the wetland ecosystem degradation seriously affects the bio-resources of the study sites. A sustainable technology should be adopted to prevent the degradation of hilly lands and conservation and caring of soil resources in the basins.

Dugongs (Dugong dugon) and most sea turtles are threatened by gill nets and other human activities worldwide. In the Red Sea these animals are potentially isolated from populations in other areas of the world. This isolation would make recovery following major population decline in the Red Sea unlikely. Protected areas are promoted as a management tool to safeguard these animals from human activities. Elba National Park, Egypt, supports populations of dugongs and sea turtles, as well as a growing fishing industry. We undertook a survey of fishers to determine if dugongs and sea turtles formed bycatch in Elba National Park. Specifically, we quantified the proportion of fishers operating in Elba National Park who had caught these animals as bycatch in fishing nets and the proportion of fishers who perceived that sea turtle eggs were still collected. This study indicates that at least one protected area in the Red Sea is not achieving conservation objectives relating to these animals. Nine and eighty percent of fishers reported having caught dugongs and sea turtles in nets, respectively. Seven percent of fishers perceived that people still collected turtle eggs. Elba National Park is failing to protect these animals for reasons including: it is managed solely as an IUCN Category VI Protected Area; fishers lack awareness of laws pertaining to these animals; and fishers are highly resource dependent. Potential management strategies to reduce bycatch include the establishment of IUCN Category 1a Protected Areas in important dugong and sea turtle habitat, encouraging fishers to adopt fishing gear that poses less risk to megafauna and raising awareness among fishers of the protected status of dugongs and sea turtles.

The presence of the external sacs on parasitic barnacles is the most unusual characteristic found in these genera. This barnacle belongs to genus rhizocephala that parasitizes crabs. Parasitization by sacculinids induces severe modifications in morphology, behavior and reproduction of their host (Brachyuran crabs: Portunus sanquinolentus). The present field study was carried out two landing center from Annankoil and Mudasalodai during January 2011– December 2011. It was found that total catch of infected crab was 12.4% from Annankoil and Mudasalodai landing center. The frequently infected male and female crab ratio was 66.3% and 33.7%. External parasites were found on crabs ranging from 56 mm to 88 mm in carapace width.