World Aquaculture September 2018

WWW.WA S.ORG • WORLD AQUACULTURE • SEP TEMBER 2018 29 A quaculture and fisheries scientists would no doubt agree unanimously that the well-being of aquatic animals is strongly affected by the condition of the water in which they live. Nevertheless, university-level students of aquaculture and fisheries receive surprisingly little training in water quality and other aspects of water science. Most aquaculture and fisheries students take a course in limnology that provides a general coverage of physical, chemical, and biological processes in lakes. Although they also take courses about aquaculture or fisheries management that touch on selected aspects of water quality in a cursory way, this exposure to water quality hardly serves as a well-rounded introduction to the subject. Soil rather than water is the milieu for most crop plant production. It is interesting to contrast the curricula in aquaculture and fisheries programs with those in agronomy and soils. Agronomy and soils students are required to take a basic soil science course that usually is quite thorough. They also must take some combination of courses such as soil morphology, soil chemistry, soil physics, soil microbiology, soil fertility and soil conservation. Auburn University has trained many aquaculture and fisheries students at undergraduate and graduate levels. I had the opportunity at this institution to teach a course focusing on general water quality for upper-level undergraduate and graduate students and to develop and teach a graduate course in aquaculture water quality management. I have taught the general water quality course since 1971 and the other course since 1974. The purpose of this article is to give some suggestions on what should be taught in a general water quality course and to provide some opinions about the status of water quality education for aquaculture and fisheries students. Suggested Content for a General Water Quality Course A general course in water quality should provide students an opportunity to learn the fundamental aspects of the subject. The goal is for students to learn enough to understand howmajor water quality variables effect fish and other aquatic life. The course also should prepare aquaculture students for further study about water quality management. The contents of the course provided here is offered as a possible guideline to anyone desiring to initiate a course on general water quality for aquaculture and fisheries students. The different course divisions are presented as narrative rather than as an outline. This was done to point out why certain topics should be included. Different water quality variables tend to be strongly interrelated as a change in the concentration of one variable usually is associated with changes in other variables. Moreover, water quality conditions affect biological processes and vice versa . There is no ideal or completely logical starting point, so the order of the class topics can be arranged according to the instructor’s preference. The number of 50-min lecture periods devoted to a Water Quality for Aquaculture and Fisheries Students Claude E. Boyd section is given at the end of each. There are 40 lectures and three additional 50-min periods for tests. Of course, a final examination is given at an assigned time. Introduction to course. The importance of water in natural ecosystems and for human use is summarized, water quality is defined and the importance of water quality to beneficial uses of water is explained, with particular emphasis on aquaculture and fisheries. A few comments are made related to the urgency for better water conservation and water quality protection as a result of global population growth and looming water shortages in many regions. A 20-min test to assess the general water quality knowledge of students entering the course is given. (2 lectures) Physical properties ofwater. Physical properties of water include molecular structure, hydrogen bonding, thermal characteristics, vapor pressure, density, surface phenomena, viscosity, elasticity and com- pressibility, water pressure, dialectic constant, conductivity, and trans- parency. Several examples of how these properties influence water’s behavior are given, e.g., hydrogen bonding and phase changes, how cohesion and adhesion cause capillarity, the water temperature-density relationship allowing thermal stratification of lakes and ponds, and the effect of high dielectric constant of water on solvent action. (2 lectures) An overviewof hydrology andwater supply. This section begins with a presentation on the amounts of water and renewal times of water in the different compartments of the hydrosphere and a description of the hydrological cycle. The world presently has as much water as it ever did and ever will, and the main reasons for water shortages are mentioned. Emphasis is given to the fact that aquaculture facilities should be sited, designed, constructed, and operated in harmony with local hydrologic conditions. Other topics include basic methods of measuring precipitation, evaporation, evapotranspiration, and runoff (including streamflow) and use of hydrological data to make water budgets for watershed ponds, embankment ponds and lakes. The section ends with a brief discussion of world water balance, water availability, the water footprint and global water use. (3 lectures) Dissolved solids. This section is introduced by identifying the dissolved solids (major anions and cations, trace elements, and dissolved organic matter) and pointing out which dissolved substances are plant nutrients. The distinction between dissolved and suspended matter is made and methods for determining total dissolved solids, salinity, electrical conductivity, the various fractions of the solids, and calculation of charge balance (anion-cation balance) are presented. It is useful to show data on concentrations of major ions and total dissolved solids from different types of water bodies (streams, lakes, ponds and groundwater aquifers) in regions with different geological characteristics and climatic regimes. These data may be used to illustrate how characteristics of soils and other geological formations, temperature, rainfall, evaporation, contact time between water and minerals and certain characteristics of groundwater interact to govern ( C O N T I N U E D O N P A G E 3 0 )