SynopsisMacrobenthic bioturbation and microbial activity can have major ecological effects on present day marine sediments some of which are also seen in the fossil record. The coastal and estuarine sediments in the Clyde Estuary area are described. They contain very high densities of benthic macroorganisms and microorganisms. These organisms have dramatic effects on the physical and chemical properties of sediments, and field and laboratory studies have shown that many geotechnical and geochemical properties of sediments are dictated by them. The effects can be on a microscale of a few millimetres horizontally or vertically (micro-spatial variation), or can have large scale consequences over hundreds of metres (macro-spatial variation).Sediment stability (shear strength and critical erosion velocity), permeability and particle sedimentation are all altered by macro-invertebrate bioturbation or microbial activity, and many chemical properties such as Eh and pH may be influenced in a similar manner.Biological activity may therefore play a major role in modifying sediment geotechnics and early sediment diagenesis. It also has direct relevance to the siting of man-made structures on the sea-bed and to sediment stability and transport in estuaries. In situ seeding experiments may lead to biological control and manipulation of these most important field phenomena.
Sediment cores were set up to study microbial colonisation and interactions on marine sand grains under enrichment conditions. Cores were enriched with photosynthetic media in the light and dark (PL, PD) and heterotrophic media in the light and dark (HL, HD), and were incubated for 25 days. Sediment chlorophylls were then measured by acetone extraction, viable heterotrophic bacteria by plate counts, and numbers of cells mm-2 sand grain surface by s.e.m. Chlorophyll a occurred in all sediments but was highest in the PL sediment. Bacteriochlorophyll a was only observed in the HL sediment. Heterotrophic viable counts were high in the HL and H D sediments. Dense growth of diatoms and blue-green algae, and a marine fungal Thraustochytrid sp. occurred on PL grains. The blue-green alga Schizothrix was often associated with the diatom Amphora on PL grains. Many different bacteria grew on HL and H D grains and some unusual colony and cell morphologies were recorded (Caulobacter, Flexibacter, polymer strands). Characteristic flakey material sometimes occurred in hollows on grains. The results are discussed in relation to microbial communities in low energy sedimentary environments.
Growth of photosynthetic and non-photosynthetic microorganisms attached to intertidal sediment particles was enhanced by enrichment media. Scanning electron microscopy was used to study species interactions. Dense microbial growth was observed on flat and uneven sand grain surfaces. A specific association was observed between an Amphora (diatom) and a Schizothrix (blue-green alga) species. There was evidence of growth inhibition between adjacent microbial colonies. A peculiar microorganism showing stellate microcolonies and an unusual cell morphology is reported.
Problems associated with pollution are becoming more severe as industrialization advances rapidly. Inorganic and organic wastes, both water-soluble and insoluble, are discharged into the aquatic environment, contributing to one of the most critical problems: water pollution. The discharge of waste in water channels allows heavy metal ions, which are toxic to all kinds of life, to enter the food chain. Lead, nickel, sodium, potassium, zinc, copper, iron lithium, cadmium, and chromium (VI) are among the most hazardous metal ions. Because they don't break down, metal ions build up in the environment and move up the food chain. Therefore, higher trophic level animals are more susceptible to their toxicityHeavy metals found in freshwater and sediments have been found to bioaccumulate in fish tissues. Rawal Dam, Mangla Dam, and Zabi Dam were identified as highly contaminated areas of freshwater that had detrimental effects on fish and human health. The Rawal Dam, which received a lot of industrial and sewage drainage from Punjab's metropolitan areas and industry, was significantly contaminated compared to other Pakistani Dams. Changhoz and Ghol Dams, with their massive water flows and relatively few accompanying industrial facilities, have the healthiest ecosystems of all Pakistan's dams. Changhoz Dam's freshwater fish are considered to be safe for human consumption. Heavy metals are accumulated by migratory birds at Rawal Dam from eating fish from freshwater reservoirs. Heavy metal pollution has been linked to a variety of social, ecological, and economic issues. The detrimental effects of heavy metals on aquatic organisms and human well-being can be reduced if wastewater is purified before being released into freshwater.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.