For those of an academic or scientific disposition, following this brief look at my research into using fish as a down loadable record of the environmental conditions they find themselves in, there is formal paper on the subject. But for those who want to know what its about without all the heavy stuff, here's a layman's guide into Fluctuating Asymmetry (FA) and it's value as a biological monitoring tool. Also included on this web site is my full thesis which brings in other areas of research around the same subject. Having spent several years working on the project, I can say in all honesty that I am one of the few people in the country who I actually spent years doing FA at university and still came out of it with a PhD.

Most animals, including fish, are classed as being bilaterally symmetrical. In other words, both halves of their body either side of an imaginary dividing line running from the head to the feet are identical. A couple of good examples of animals that do not have bilateral symmetry are the fiddler crab which has a very much bigger claw on one side of its body than the other, and flatfish such as dabs and plaice which have both eyes on one side of the body positioned on one side or the other of the mouth. But even animals which supposedly have bilateral symmetry will to some extent stray away from the perfect mirror image. In that respect, absolute perfection is rare.

Bilateral symmetry is very tightly controlled by an animals genetic blueprint. It is not in most animals best interests to have bits on one side of its body develop differently to those on the other. This would lead to all sorts of problems, and in the wild animals could find it difficult either to hunt or to escape. As you would expect, some aspects of symmetry are more important to an animals well being than others. Having paired fins of significantly different lengths or surface areas would be a major problem. But having fin ray thicknesses differing marginally across a pair of anal fins is hardly going to be life threatening. So control over minor paired traits which are not going to cause problems if they do stray a little from perfect symmetry is less rigidly enforced than in traits where it really does matter.

In a perfect world, even fin rays would remain identical. Introduce stress into the life of that animal, and genetic control over the development of some of these less important traits starts to suffer. For wild animals, stress invariably comes from their environment and includes such things as predation, temperature variation, food availability, and for my particular area of research, pollution. The two most common threats to the fish we as anglers like to catch are over fishing and pollution. Over fishing is straight forward enough. Taking too many fish can be measured in all sorts of ways. The most important factor so far as we are concerned is that when they are gone, thats it. Presence or absence is a straight forward easy parameter to measure. When pollution wipes out fish it is exactly the same. The problem is that not all pollution is immediately lethal. Its effects can be much more subtle leading to population crashes of a less readily attributable nature.

Fishery scientists when they survey a river, a lake, or even a stretch on the coast, normally base their results on two aspects of monitoring. They can either take samples of water, sediments and even animal or plant tissue for chemical analysis, or they look at the species make up of whole ecosystem. By this I mean a survey of all the animals living on that patch and scoring them according to their pollution tolerance. A river for example, might be chemically sampled once a month, and biologically surveyed once in each season. From the resulting data, a classification level will be determined. Classification of rivers falls into 5 categories or levels with level 1, which includes pristine at the top end of scoring being the best, and level 5, which can include grossly polluted or even biologically dead as a worst case scenario at the other extremity.

The problem with surveying and classifying aquatic environments in this way are as follows. If a sampler turns up 5 minutes before a lethal slug of pollution travels down a river killing everything in its wake, it will be missed, and the sample will show good water quality. Similarly, if he or she turns up 5 minutes after it has finished passing through, despite the total carnage this particular pollutant might have caused it will have been missed, and again analysis will show the usual standard of water quality as the polluted water is replaced by clean water coming from upstream. Dipping a can into a river and filling a bottle takes a couple of minutes at most. So with a sampling frequency of once a month, the chance of some pollution problems not being detected chemically is extremely high.

Complimenting chemical sampling in painting a more accurate picture is the use of biological indices which involve macro-invertebrate sampling and scoring. But once again, depending on the sampling frequency, problems can be missed. What happens here is that the sampler will wade into the water at a predetermined representative spot with a fine mesh net and using the feet, disturb the river bed substrate on the upstream side of the net. This dislodges invertebrates living under the stones or in the bed material which are then carried by the flow into the net. Anything and everything can show in the net from small fish through to molluscs and worms. But of primary interest are macro-invertebrates such as insect larvae which are put into a tray of water and identified down to family level.

Different families of animals in a river have different degrees of tolerance to organic pollution. Mayfly and stonefly larvae are the highest scorers in all of this because they need clean well oxygenated water. What happens when a farmer looses slurry or silage liquor into the water is that the bacteria which feed on it in order to break it down suddenly multiply to take advantage of the feast. One bacteria can divide into 2 in 28 minutes, both of which divide again 28 minutes later, and so on. After 9.3 hours, 1 bacteria can become 1,048,576 as can the many others present at the time, all of which require oxygen to survive which is stripped from the water suffocating fish and invertebrates as a result. Occasionally fish kills are caused by toxic spillages. But the most common cause of pollution in freshwater is organic material from farms, sewage works and industry

At the low scoring end of the invertebrate list are animals like tubificid worms and blood worms, the later being the larvae of midges. These have no problem surviving in oxygen starved environments. Both are red in colour resulting from haemoglobin concentrations which allows them to store oxygen and survive. And of course there is a whole range of other animals between these two extremes which also have scores determined by their pollution tolerance. These numbers are then totted up to derive the waters BMWP (Biological Monitoring Working Party) score, plus what many feel is an even better index known as ASPT (Average Score Per Taxon) derived by dividing the BMWP score by the number of scoring families producing it. This evens out any blips caused by rogue animals drifting through at the time.

Biological indices are much more reliable than chemical sampling. When the high scoring species are deterred from colonising a stretch of water because oxygen levels are not high enough to sustain them, they will not usually be encountered along that stretch for many months after the pollution problem goes away. It takes time to recolonise through egg laying and down stream drift. So you don't necessarily have to be right on the case the day a problem occurs. Biological sampling can also identify offending inputs from pipes or ditches delivering the pollutants to the main river. When you suddenly find high scoring animals back on the scene at a given point, you know the problem must start down stream of there.

The big drawback with biological indices is that they rely solely on presence or absence. In short, life or death. But what if the problem isn't lethal. What if animals living there are experiencing a highly stressed sub lethal environment. And more to the point, what if those animals are fish. As with the invertebrates, some fish species won't be able to tolerate as much pollution as others and may well be absent as a result. On other occasions they might be just about hanging on in there in poor physical condition and stunted through lack of food because the invertebrates many rely on as the mainstay of their diet are also having a hard time of it. This type of problem won't show up in a presence of absence sampling regime. This is where fluctuating asymmetry (FA) comes in.

As I have already said, animals are known to loose control of certain aspects of their bilateral symmetry when they are stressed. The questions I set out to answer were does that loss of control increase on a pro-rata basis with increased levels of stress, and would it be possible to 'down load' the information recorded in the bodies of these animals - in this case fish, in a format that would allow scientists not only to identify sub-lethal pollution events, but measure their severity and maybe even suggest an approximate start or end period. To do this I needed to find an animal that was prepared to live in the wild at any levels of pollution from pristine through to grossly polluted. That animal tuned out to be the three spined stickleback.

Sticklebacks are amongst the hardiest fish on the planet. Besides living in rivers, canals and ponds, they are also found in estuaries and rock pools, and on occasions many miles out to sea. Not only are they capable of surviving where virtually nothing else will in terms of organic pollution loading, they are doing it all over the country right now. When you find dead sticklebacks in a fish kill resulting from organic pollution, you know its a bad one. Equally important from a research point of view, sticklebacks are widely distributed, abundant, easy to work with, and readily caught with a small hand net.

The next thing I had to do was get hold of some historical biological survey data for the whole of the North West and select from it 50 sites representing all 5 levels of water quality. I then visited each and took away 30 mature fish, later measuring the 9 paired traits I had selected and calculated an average FA value for each site. From the biological survey data I also calculated the average water quality value for the 3 years preceding catching the fish as sticklebacks have an average life span of around 3 years. By feeding the data into a statistical analysis package known as Minitab allowed me to produce a regression analysis which in essence is a straight line graph plotting water quality from the biological surveys against FA. From this I was able to make certain statements about the quality of other stretches of water by marking their FA results on the map and reading off the corresponding BMWP or ASPT value.

It goes without saying that when you undertake a research project of this type, all sorts of statistical hoops have got to be successfully jumped through before anyone will give any credibility to your work. All of those criteria were met. Now anyone catching 30 sticklebacks from any stretch of water and determining their FA in the way I did will be able to put their results onto the graph and come away with valuable water quality predictions from waters with no previous historical data. In addition to this, by selecting different age groups, in this case based on size, it might even be possible to estimate how long a problem has been going on for up to a maximum of 3 years. Older fish affected when the younger ones are not suggests a one time problem that has now gone. Young fish affected and older fish not would be due to a more recent event.

The reason why I can say this with such certainty is because I carried out two other interesting support experiments. The first was to establish whether FA is reversible once the stress source has been removed. If fish were able to recover my project would have been in serious difficulty. By placing fish of known FA status from a highly stressed environment in a purpose built fish free pond and leaving them for a year, I was able to compare before and after FA results. During that year FA increased by around 19% which matched exactly the average size increase of the fish. So FA is not reversible. When the stress is removed, the FA stops accumulating, but as both traits in the pair then continue to grow at the same rate, the size difference between them also grows at that rate too.

The other question I also had to answer was could FA be passed forward across generations. If it could, then the FA measured in a population of fish might have nothing to do with water quality. If the parents had been stressed then the problem had been rectified prior to the birth of their offspring, if FA was then passed forward at the same rate to fish born and brought up in the now stress free environment it would be worthless as a biological monitoring tool. Fortunately, the fish from the grossly polluted stream put into the pond spawned during their year of freedom and their offspring had very low FA values, comparable with those from other populations taken from similarly pollution free waters.

So, it is possible to 'down load' environmental data from fish, whether they live in clean or polluted environments. Whats more, it is also possible to do this with any species of fish (or invertebrate or plant). You would of course need to construct a new regression plot using data from that particular species. And with some fish known to live far longer than sticklebacks, it should be possible to make more subtle statements. Bass for example which can live for more than 20 years would in some ways be ideal. The downside to using bass would be that it involves destructive sampling and they are probably too thin on the ground anyway to generate the right levels of data, which is why a small, abundant, territorial marine species would be required. But it can be done, and indeed it should be done in controversial situations such as around questionable sewage and trade effluent discharges.

To see an FA Paper Example in full, CLICK HERE to open up the document