Bio-technology Made Simple : Using Craydids as Bio-indicators for Monitoring of pollution in water

 Introduction :

Craydids , also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, mudbugs are freshwater crustaceans resembling small lobsters

Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea.

Habitat:

They breathe through feather-like gills. Some species are found in brooks and streams, where fresh water is running, while others thrive in swamps, ditches, and paddy fields. 

Most crayfish cannot tolerate polluted water, although some species, such as Procambarus clarkii, are hardier. 

Food  & Nutrition :

Crayfish feed on animals and plants, either living or decomposing, and detritus.

Anatomy : 

The body of a decapod crustacean, such as a crab, lobster, or prawn (shrimp), is made up of twenty body segments grouped into two main body parts, the cephalothorax and the abdomen.

Each segment may possess one pair of appendages, although in various groups, these may be reduced or missing.

Geographical distribution and classification

The three families of crayfish

Astacidae: Austropotamobius pallipes

Cambaridae: Procambarus alleni

Parastacidae: Cherax pulcher.

Three families of crayfish are described, two in the Northern Hemisphere and one in the Southern Hemisphere. 

The Southern Hemisphere (Gondwana-distributed) family Parastacidae, with 14 extant genera and two extinct genera, live(d) in South America, Madagascar, and Australasia. 

Uses of Crayfish to humans :

Crayfish as Bioindicators for Monitoring level of pollution and ClO2 :

Monitoring of Pollution :

The Protivin brewery in the Czech Republic uses crayfish outfitted with sensors to detect any changes in their bodies or pulse activity in order to monitor the purity of the water used in their product. 

The creatures are kept in a fish tank that is fed with the same local natural source water used in their brewing. 

If three or more of the crayfish have changes to their pulses, employees know there is a change in the water and examine the parameters.

Scientists also monitor crayfish in the wild in natural bodies of water to study the levels of pollutants there.

Crayfish as Bioindicators for Monitoring ClO2 :

The research was conducted by : 

Research Institute of Fish Culture and Hydrobiology, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, 

Faculty of Fisheries and Protection of Waters, 

University of South Bohemia in České Budejovice, , Czech Republic

The effect of long-term exposure of signal crayfish to different levels of ClO2 were investigated and assessed through the observation of heart rate, diurnal rhythm and mortality.

The study showed the changes in the heart rate of unstimulated spiny lobster and the ClO2 exposed signal crayfish were similar in the premolting period.

The heart rate of an unaffected lobster increased 1–2 h before molting to a peak of 80–120 bpm and declined about 15 min before the beginning of molting. 

Other uses of Cray fish :

Food :

Crayfish are eaten worldwide. Like other edible crustaceans, only a small portion of the body of a crayfish is eaten. In most prepared dishes, such as soups, bisques and étouffées, only the tail portion is served. 

Bait :

Crayfish are preyed upon by a variety of ray-finned fishes,and are commonly used as bait, either live or with only the tail meat. They are a popular bait for catching catfish ,largemouth bass, smallmouth bass, striped bass,perch & pike.

Transporting crayfishes as live bait has also contributed to the spread of zebra mussels in various waterways throughout Europe and North America, as they are known to attach themselves to exoskeleton of crayfishes.

Pets

Crayfish are kept as pets in freshwater aquariums. They prefer foods like shrimp pellets or various vegetables, but will also eat tropical fish food, regular fish food, algae wafers, and small fish that can be captured with their claws.