Another Exotic animal that eats the exotic invasive plants is the Nutria (Myocastor coypus), which is a beaver-sized rodent that is native to South America. In the 1930's, nutria were brought to Louisiana for a fur-farming operation and subsequently were liberated in substantial numbers by hurricanes and accidental escapes. They quickly colonized and spread through-out the Louisiana marshes.
Nutria were not reported as exotics in Florida, until the 1950's, when the first of these animals were found in the Panhandle, the Apalachicol & Choctawhatchee river basins, and in Hillsborough River drainage near Tampa Bay.
In 1972, the Game & Fresh Water Fish Commission, found nutria living in ponds and along canals at several large dairy farms. These farms had several series of pollution polishing ponds and canals to trap and settle out organic waste and for the run-off from the dairy's 1,000-3,000 head of cows.
Exceedly high numbers of nutria were thriving and living there with no apparent ill-effects in these manure sewage lagoons. It was noted that these animals were capable of living and thriving, and breeding in high numbers in these areas.
The fertilizing effect of dairy runoff produces a growth of shoreline vegetation which the nutria utilize heavily on a year round basis. And in addition these lagoons and canals are normally chocked and blocked by dense carpets of water hyacinths. Farmers use the water hyacinths to help cleanse the pollution from the sewage run-off and the nutria feed on the young tender shoots of the hyacinth plants.
In Florida, the adult female nutria breed on a year round basis. All the females collected during a 12 month period were pregnant or lactating. This contrasted with the breeding cycle in Louisana, marshes where there is a single main breeding cycle season in December & January, and a smaller one in June & July. The average litter size at the dairy farms was found to be 5-7 embryos, and a littler size of 3-10 young. The pregnancy lasts about 129-139 days.
With the length of gestation it suggests that a continious breeding cycle under unlimiting environmental conditions produces 2.7 littlers born per adult female every single year. In Florida, the nutria the conditions would represent a total maxinum breeding potential which would average about 15 young per adult female per year. And it was noted that the young mortality rates were very small.
In repect this means that nutria are an exotic species that thrives well in the Florida wilds. Perhapes the exotic pythons rodent feeding will make a dent in the nutria colonies.
This topic has mainly been about aquatic weeds and their over-growth, and about the types that become invasive and take over large bodies of water in fresh water lakes and rivers, streams and canals.
I am now going to talk about "Water Fertility" which is important if you, like I, like to fish. You don't have to be a biologist to catch fish, but it helps to know the areas that fish like to be in and why. Also the following information will explain what causes fish to die off or to live happily in ponds or lakes, or river areas.
This term of water fertility refers to the amount of nutrients, such as nitrogen and phosphorus, dissolved in the water. a body of water with high fertility is said to be "eutrophic"; moderate fertility, "mesotrophic", and low fertility, "oligotrophic."
Fertility, in its self, has very little effect on the daily life of fish. If all other habitat requirements are met, they can easily live in water at any of the fertility levels. But fertility does play a role in how many fish a body of water can produce. As in the levels of dissolved nutrients in the water determines how much phytoplankton is produced and this determines how much food is available to the fish.
Fertility has yet another indirect influence on fish, as it is the primary factor in determining the level of dissolved oxygen in the water so it controls where fish can live and where they cannot.
Examples:
Eutrophic lakes, are shallow and weedy, with highly fertile water. Heavy algae blooms develop in the summer months.
Mesotrophic lakes, usually have a moderate depth with good water clarity and water fertility and some weed growth.
Oligotrophic lakes, are generally deep and clear, and infertile with sparse weed growth.
04-10-2013, 12:14 PM, (This post was last modified: 04-10-2013, 12:32 PM by 4sweed.)
All fish vary in their dissolved oxygen needs. Oxygen levels are measured in parts per million (ppm). When water is fully saturated with oxygen, dissolved oxygen level is about 10ppm, depending of course on water temperature. It may be noted that fish are much easier to keep in your pond when the water is cold. Fish in cold water require less oxygen and the water can hold more oxygen.
Oxygen gets into water through the contact of air and photosynthesis by aquatic plants. It is then consumed by respiration of aquatic organisms like bacteria and fish.
In fertile ponds or lakes, organic matter is so plentiful that oxygen is consumed faster than it is replaced. In the summer time often the pond or lake, stratifies, and the layers of decaying organic ooze on the bottom rapidly consumes oxygen and with no circulation to replace it, oxygen levels wane, forcing the fish into shallower areas of water.
The fall weather replenishes oxygen levels, but they will dip again in winter. If the snow and ice covers the pond or lake enough to prevent sunlight penetration, plants cannot produce oxygen through the process of photosynthesis, so the amount of oxygen plummets, and if it plummets to far, the fish will begin to die. Dissolved oxygen is replenished in the water by oxygens contact with air. Wind circulates the water, carrying oxygen to the fish in the depths. In the summer months the lower layer does not circulate, so no oxygen is added. However, when the leaves of plants are exposed to sunlight, oxygen is produced through photosynthesis. Again though when the sunlight cannot reach the plants, no oxygen is produced.
Although, all fish are cold-blooded, the different species prefer different water-temperatures. Examples: coldwater fish like trout or salmon like water temperatures in the fifty degree range. Other fish like pike and perch, like sixty degree temperature, and warmwater fish like bass and sunfish, and catfish like water temperature in the seventy to eightly, degree range. However, all of these types of fish, as well as, many others need food and will leave their temperature ranges to find food.
So in summer when the oxygen levels drop in deep water, fish go into shallow water where oxygen levels are higher. Most warm water fish can tolerate very cold water. I have seen this in my brother's fish pond where due to a leak his pond water level dropped and his koi were swimming in much shallower water than normal. In fact there fins were sticking up out of the water. But in this shallow water they remained healthy. Luckly, he was able to repair the leak and bring the water levels up to normal levels. In Florida, we had a very large pond and our koi preferred the deepest areas of the pond during the summer, and could only be brought to the surface by feeding them.
04-11-2013, 02:25 AM, (This post was last modified: 04-11-2013, 03:03 AM by 4sweed.)
Water is densest at the temperature of 39.2 degrees. When it becomes warmer or colder it becomes less dense. This density is the difference that causes most ponds or lakes to stratify into 3 temperature layers. The deepest and coldest, densest layer is called the "Hypolimnion"; and the shallowest and warmest, lighter layer is called the "Epilimnion." Between these two layers is a layer called the "Thermocline" where temperatures change rapidly.
The epilimnion which is warmer and lighter water, floats on top of the cooler, heavier water in the dephs. And because this water is lighter it is easily circulated by the wind. The layer called thermocline may have some water circulation, but the water below it circulates very little.
When a pond stratifies in early summer the stagnation process begins, as decaying organic matter on the pond bottom, along with the living organisms in the water consume dissolved oxygen. With no circulation to restore it and no aquatic plants to produce it, the oxygen levels in the hypolimnion layer begin declining. Just how fast they decline depends on the water fertility.
The temperature layers remain constant through the summer, as long as the weather stays warm enough to keep the surface water several degrees warmer than the water that is in the deepest layer. But when the fall cool weather comes and the shallowest water reaches the same temperature as the depths, the fall turnover begins. Since all the water in the pond is now the same temperature and density, the wind can now circulate the entire water mass. As the surface of the water continues to cool down, the water becomes denser then it is in the deepest part, so it sinks, which helps the mixing process.
The mixing of the layers from the surface to the bottom continues through the fall. and in the northern areas the surface water freezes, but the water on the bottom stays several degrees above the freezing temperature. If water did not have this unique property of being densest at a temperature just above freezing, ponds and lakes, would freeze up completely to the bottom.
Note: In the fall the pond is still stratified into three different temperature layers. Fish stay in the upper two layers, because the oxygen levels are two low in the hypolimnion layer. In the mid-fall the upper layer cools down, and surface water starts to sink, thus starting the turnover process that scatters fish to all depths. In late fall the surface water is cooler than the water on the bottom, as practically all of the pond fish are in the hypolimnion layer, the deepest part of the pond.
If you have a small or medium, or large pond in your backyard, this information should help you to understand how fish live throughout the different seasons and how to prevent fish losses from overgrowth of aquatic weeds or from lack of the proper aquatic plants. even if you feed your fish daily. Having some aquatic plant-life in your pond can insure that oxygen will be produced naturally in your pond.
I mentioned fishing in one of my above posts, because several friends of mine raise trout and bass, along with their koi, in backyard ponds. Though they may fish once in a while from their pond, their children have given the fish pet names. I think "Charley" and "Sam", are the two biggest koi in their pond. I have handfed the koi, but leave the bass to those who don't mind getting nipped by a hungry bass after a frog.
Just in case your wondering what I mean't by warm-water fish and cold-water fish, here are some examples: Flathead Catfish, Channel Catfish, Bullhead, White Bass, Bluegill, Largemouth Bass, Striped Bass, and Crappies are considered warm-water fish. (epilmnion layer warmest)
Bottom depth cold-water fish: Brown Trout, Cutthroat Trout, Chinook Salmon, Rainbow Trout, Coho Salmon, Brook Trout, and Lake Trout (hypolimnion layer coldest)
Fish Habitat
This is very important for keeping your pond fish healthy and happy. You want to provide your fish with the right kind of cover and proper range of water temperature, adequate dissolved oxygen and a reliable supply of food. If you skip any one of these important elements long-term survival of your pet pond fish would be almost impossible.
04-11-2013, 07:38 AM, (This post was last modified: 04-11-2013, 08:14 AM by 4sweed.)
Within fish habitat the needs of the type of fish kept must be met. In backyard ponds, ways to keep the circulation of the water moving is done by means of waterfalls or constantly flowing underground springs. Sometimes depending on your landscaping and surrounding area, you might be able to have the advantage of using both fresh water underground water streams and manmade waterfalls. This constantly adds fresh moving water to your pond which helps keep the oxygen levels at higher levels year round.
Many of the backyard pools I have seen are totally manmade. The areas for the pool are hand dug and crafted in a fashion that creates a natural looking environment with mostly manmade supplies. The bottom of the pools are covered with black rubber tarps and the edges are layered with different types of flat rock to create attractive borders and waterfalls. Certain plants are added in the pools, usually in pots to prevent the roots from spreading, and placed deep underwater or along the shallow edges of the pool. Bridges that span over the deepest pools are sometimes added to provide an overview of the fish below. Rocks are placed in such a fashion to provide shaded areas, as well as, hiding places from predators. From simple designs to massive ponds, each has its own charm and brings enchantment in the way of a quiet peaceful area for people, to enjoy their fish.
If you have lots of talent or money this fish pond is one to consider.
If you live in the country and have a pond such as this one in your backyard you might consider having some gamefish, as well as, koi or goldfish, in your pond. This video shows how to add fish to a natural pond setting.
All fiish species have a set of senses that enable them to survive in their aquatic settings. When the pond water is clear fish rely on their vision to find food and avoid predators. When the pond is muddy from heavy rainstorms, they rely on their hearing and lateral-line system. Even though every fish has each of the senses, it varies from species to species.
Vision:
In all fish, the retina of the eyes is equipped with rods and cones. Fish who are found in shallow water have better color vision then those that are deep-water species. Good color vision would be meaningless to fish in deep water because in the depths water acts as a color filter. Red disappears at 10 feet and yellow at about 20 feet. While blue may be visable at 50 feet or more if there is adequate light penetration. And fish that have color vision might not have night vision, because they lack enough rods in their retinas. Just how far a fish can see depends more on the clarity of the water, then their visual acuity.
Lateral Line System:
This type of sense enables fish to pick up vibrations from the water to help them detect predators. The lateral line is a row of pores along the sides of each fish, extending from the gill to the base of the tail. These pores are connected to a series of nerve endings that can sense even the slightest vibrations and transmit them to receptors in their inner ear. Using this lateral line, the fish can figure out if predators or prey are present and how big they are and how fast they are moving and in what direction they are going. This lateral line also helps fish who like to swim in unison to stay together.
Hearing:
Fish have inner ears which are made up of tiny bones that pick up sound and semi-circular canals that help maintain their equilibrium. They do not have an ear drum, but instead vibrations are sent to their ears through their body tissues.
Smell and Taste:
Most fish have acute sense of smell and can detect odors of nearby predators and prey, if the current alouds it. But some fish rely on scent more than smell. In some fish this sense of taste helps them find food in muddy water or on the bottom of the pond. Some fish like catfish have taste buds in their whiskers and on their skin to aid in the finding of food.
