The following identification charts gives the reader a general idea on the aquatic life that can be found in freshwater aquaculture ponds.
Rotifers:
Anterodorsal margin with semicircular notch
Lengths: dorsal plate 200 - 270 µm, ventral plate 170 - 250 µm, toes 50 - 75 µm.
Widths: dorsal plate 90 - 189 µm, ventral plate 80 - 105 µm.
Ecology:
Occurs most frequently in eutrophic environments. Has been observed attached to colonies of Chlorella and Chlamydomonas reinhardti. Bacteria, green algae, and diatoms are part of the diet.
Gastropus hyptopus:
Well-defined, usually wavy foot opening, much larger opening than Gastropus stylifer.
Synchaeta oblonga:
Molluscs:
Snails in the family Physidae have shells that are sinistral, which means that if the shell is held with the aperture facing the observer and the spire pointing up, then the aperture is on the left-hand side.
The shells of Physella species have a long and large aperture, a pointed spire, and no operculum. The shells are thin and corneous and rather transparent.
Crustacea:
Amphipoda :
The body of an amphipod is divided into 13 segments, which can be grouped into a head, a thorax and an abdomen.
The head is fused to the thorax, and bears two pairs of antennae and one pair of sessile compound eyes. It also carries the mouthparts, but these are mostly concealed.
The thorax and abdomen are usually quite distinct and bear different kinds of legs; they are typically laterally compressed, and there is no carapace.
The thorax bears eight pairs of uniramous appendages, the first of which are used as accessory mouthparts; the next four pairs are directed forwards, and the last three pairs are directed backwards.
Gills are present on the thoracic segments, and there is an open circulatory system with a heart, using haemocyanin to carry oxygen in the haemolymph to the tissues. The uptake and excretion of salts is controlled by special glands on the antennae.
The abdomen is divided into two parts: the pleosome which bears swimming legs; and the urosome, which comprises a telson and three pairs of uropods which do not form a tail fan as they do in animals such as true shrimp.
Branchinella sp. (Anostraca) :
Branchinella is a crustacean genus in the family Thamnocephalidae. This fairy shrimp genus is found across many parts of the world, but especially western Australia and southern Africa.
Several species are threatened by habitat destruction, and B. latzi might be extinct. The latter species was formerly found in waterholes at Uluru, but these have become polluted with urine and faeces of hikers, and the shrimp was absent in a recent survey.
Daphnia carinata:
The properties of Daphnia carinata King as a grazer for use in biomanipulation trials were investigated. Mesocosm experiments suggested that in water from a lake where D. carinata was scarce, phytoplankton was nutrient-limited and the manipulated biomass of zooplankton had no effect on total chlorophyll a, whereas in water from a lake where D. carinata was dominant, nutrients were not limiting and total chlorophyll a was negatively correlated with the manipulated biomass of zooplankton.
When offered lake phytoplankton in feeding trials, D. carinata consumed all items present, including colonies of cyanobacteria and long filaments of diatoms. In large outdoor tanks with natural plankton, the biovolume of prokaryotic ultraplankton (possible predecessors of cyanobacterial blooms) was consistently reduced in the presence of D. carinata.
There was no evidence of an adverse effect of single-celled Microcystis aeruginosa containing the peptide toxin microcystin-LR on D. carinata grazing rates or survival.
Different concentrations of microcystin-LR in solution covering the range of toxicities observed during M. aeruginosa blooms (5-500 nM) had no effect on D. carinata grazing. The suppression of phytoplankton biomass by D. carinata grazing is one of several possible mechanisms that might be considered for biomanipulation in Australia.
Boeckella sp. Calanoida copepod:
The calanoid copepod, Boeckella gracilipes, is the dominant crustacean zooplankton in South Andean deep ultra-oligotrophic lakes.
Eucyclops sp. Cyclopoida copepod:
Copepods (play ; meaning “oar-feet”) are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic (drifting in sea waters), some are benthic (living on the ocean floor), and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests, bogs, springs, ephemeral ponds and puddles, damp moss, or water-filled recesses (phytotelmata) of plants such as bromeliads and pitcher plants.
Many live underground in marine and freshwater caves, sinkholes, or stream beds. Copepods are sometimes used as bioindicators .
Canthocamptus sp. Harpacticoida copepod:
Freshwater copepods live in habitats characterized by a high degree of instability. To survive occasional deterioration of their environment copepods have evolved adaptive mechanisms like dormancy or migration in order to avoid lethal conditions and to synchronize growth and reproduction with favourable abiotic and biotic conditions.
Typical life cycles of harpacticoid, calanoid and cyclopoid copepods are presented to show strategies that have evolved to survive threatening environmental conditions.
Newnhamia sp. Ostracoda:
-
bivalved carapace, jointed in dorsal region, encloses whole animal
- carapace surface smooth, sculptured, grooved, pitted or setose, growth lines not present indistinct body segmentation
- 7 pairs of appendages, respectively, antennules, antennae, mandibles, maxillules, maxillae, thoracopods (2 pairs)
- antennules and antennae uniramous, bearing several long setae, exopodites reduced
- single or double eye spot at base of antennules, or absent
- each mandible with 3-segmented palp and branchial plate
- conspicuous branchial plate at proximal end of each maxilla
- abdomen greatly reduced terminating in 2 or more, less developed caudal rami, articulated to the posterior of the trunk
Paratya australiensis Freshwater shrimp:
The widespread distribution of the freshwater shrimp Paratya australiensis in eastern Australia suggests that populations of this species have been connected in the past. Amphidromy is ancestral in these shrimps, although many extant populations are known to be restricted to freshwater habitats.
In this study, we used a fragment of the cytochrome c oxidase I mitochondrial DNA (mtDNA) gene to examine diversity within P. australiensis and to assess the relative importance of amphidromy in its evolutionary history.
We hypothesized that if transitions from an amphidromous to a freshwater life history were important, then we would find a number of divergent lineages restricted to single or groups of nearby drainages. Alternatively, if amphidromy was maintained within the species historically, we expected to find lineages distributed over many drainages.
We assumed that the only way for divergence to occur within amphidromous lineages was if dispersal was limited to between nearby estuaries, which, during arid periods in the earth’s history, became isolated from one another. We found nine highly divergent mtDNA lineages, estimated to have diverged from one another in the late Miocene/early Pliocene, when the climate was more arid than at present. Despite this, the geographic distribution of lineages and haplotypes within lineages did not support the notion of a stepping-stone model of dispersal between estuaries.
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