Thesis Example: Background on Macrobenthos

By definition, Macrobenthos are invertebrates that live in or on the sediments. For an invertebrate to be termed as a Macrobenthos, it has to be quantitatively sampled by a 0.1 square meter. The sampling device is known as Smith McIntyre grab and purposes to retain the Macrobenthos on an o.1mm or o.5mm sieve. The standard sieve was initially 1.0mm, and it was used before and up to 1979. Afterward, it was replaced by a 0.5 mm sieve (Brey). The technique was and is used to measure the wet weight of biomasses for various species through blot-drying them first. The specimen are collected from the sea and samples placed on a blotting paper for approximately three minutes to dry off the excess water. The SI unit for measuring the biomass is mg. The weight of the biomass measured includes:

Is your time best spent reading someone else’s essay? Get a 100% original essay FROM A CERTIFIED WRITER!

Save 25%

1. The carapaces in crustaceans

2. The tests in echinoderms

3. The shell in mollusks

The Macrobenthos are categorized into four broad categories: crustaceans, polychaetes, mollusks, and other. They occupy different compartments when it comes to location and network (Caracciolo). The other group is composed of nemerteans, tunicates, coelenterates, and echinoderms. The various benthic invertebrates have different feeding mechanisms are unpredictable and uncertain in nature. For instance, the macrobenthos in the class polychaetes have well-developed jaws, and they got eyes that are packed with algae cells. Their guts are also able to digest cellulose. In low flow conditions, the polychaetes are surface deposit feeders and switch to filter feeding upon entering high flow conditions. Their modes of feeding are mainly carnivorous and omnivorous (Cartes). The crustaceans are exclusively carnivorous, and they are the type of macrobenthos you dont want to get close to. They pose a significant risk even to humans. The crustaceans are also scavengers, deposit feeders, and omnivorous. Nemerteans are carnivorous while Tunicates are filter feeders.

There are over 2,000 benthic invertebrates identified and contribute to the total biomass of taxonomic groups. A quantitative approach for biomass estimates is established by obtaining the total net weight for each taxonomic group within a locale and summing the individual grab samples. The value obtained is then divided by a total number of samples taken and the biomass expressed in g per 0.1 square meters (Collie). The effect of wild boar carcasses is that it increases this weight and mighty have the researcher come to the wrong conclusions if they are not careful enough. Good collection techniques should be employed in such research to improve the precision and reduce the percentage error. For instance, cages are necessary to hold the substrate which will, in turn, attract the arthropods for research. The arthropods are drawn to the pen through various senses such as smell and sight. Once the arthropods have been attracted to the substrate, the substrate can be removed without the arthropods escaping, and this is only possible with the use of a mesh bag that acts as a cover. The substrate in the cage is either wood sticks or quartz stones. Quartz stones are chemically stable and inactive with water quality or acidity in the environment. Both types of substrates are difficult to decompose into smaller parts. Thus, the arthropods are presumably attracted by the carrion rather than the decomposition of the substrate.

Works Cited

Brey, T. 1990. Estimating productivity of macrobenthic invertebrates from biomass and mean individual weight. Meeresforsch. 32:329-343.

Brey, T; Jarre-Teichmann, A; Borlich, O. 1996. Artificial neural network versus multiple linear regression: Predicting P/B ratios from empirical data. Mar. Ecol. Prog. Ser. 140 (1-3):251-256.

Caracciolo, JV; Steimle, FW. 1983. An atlas of the distribution and abundance of the dominant benthic invertebrates in the New York Bight Apex with reviews of their life histories. NOAA Tech. Rept. NMFS SSRF-766; 58 p.

Cartes, JE; Brey, T; Sorbe, JC; Maynou, F. 2002. Comparing production-biomass ratios of benthos and suprabenthos in macrofaunal marine crustaceans. Can. J. Fish. Aquat. Sci. 59(10):1616-1625.

Collie, JS. 1985. Life history and production of three amphipod species on Georges Bank. Mar. Ecol. Prog. Ser. 22:229-238.