A note on names- For the sake of simplicity and brevity, I will often use the Genus name in what is an academically incorrect way- simply saying Pseudiron for example, rather than the various formal and academic alternatives (e.g. full binomial name including genus and species, or abbreviated genus name along with the species name.
These notes provide details and more information to supplementvideos
Notes #1. ( Notes #1 refer to videosonHome) See mid-page of Home
Pseudiron, Collection and video date, 4 July 2009. Collection location, South Saskatchewan River at Queen Elizabeth Power Station, Saskatoon, Sk. (below).
The collecting trip was made on this date and to this site specifically to collect Pseudiron and Ametropus. (see Ephemeroptera for details on classification and discussion) In past years, e.g. a decade ago, it was possible to collect dozens of Pseudiron and hundreds of Ametropus at this site on this date. This year, after an hour of seaching, and especially sweeping in favoured areas of submerged sandbars, with their dune-like behavour of moving with the current, I was able to collect three small individuals of Pseudiron which ranged in size from about 6 mm to 10 mm in length. These are immature, perhaps 1/3 mature size at most.
As I have indicated elsewhere, (Aquatic Insects page), in the Saskatchwan River, it is my opinion that it is impossible to sample the diversity of aquatic organisms present and to understand the ecology of the system if one does not have knowledge of individual species and their life cycles, behaviours, and habitat preferences. Random sampling with standard samplers, using textbook methods, will collect only the most common and abundant species.
Again, it was hoped that Ametropus would be collected here, but none were found, even though formerly productive areas were well searched. It could be speculated that the fact that Ametropus has a full year larval life would mean that an ecological misfortune at any point in a year could eliminate an entire year's generation. In contrast, Pseudiron apparently spends up to 9 months in the egg stage- larvae being present generally from June to August. They can escape certain types of single event disasters during the 9 months in the egg stage. (see Blackfly Studies for comments on recolonization and recovery of populations and communities. More to follow on this subject).
The insect community on sandbars at this site on 4 July included the interesting mayflies Pseudiron and Siphloplecton, plus many Caenis, but there was an absence of Gomphids; all Plecoptera were absent, there were few Heptageniidae, no Ephemeridae, and no Trichoptera. The community consisted of a small number of Baetids in addition to the three mentioned above.
For results of a thorough sampling of the site, see the Queen Elizabeth Power Station pdf on the River at Saskatoon page.
River at Saskatoon, 4 July 2009
Ripple marks in sand, under 1 foot of clear water.
Collection and photography 4 July 09, location is QEPS, Saskatoon, as above. The specimen in the video is almost certainly C. amica Hagen 1861; compare with the detailed analysis of samples from 2006, see pdf Queen E.P.Station on linked page.
Five of the 12 North American species of Caenis are found in Saskatchewan. They are characterized by large square gills on the abdomen which cover a cluster of delicate respiratory gills underneath. Caenis are found in still ponds and lakes as well as in slow areas of streams and river.
Notes #3 (Notes #3 refer to theVideo page. Ephoron , Hexagenia, Isonychia,and Pteronarcys were collected at Borden Bridge, Siphloplecton was collected at QEPS at Saskatoon).
Borden Bridge, North Saskatchewan River, Saskatchewan.
Substrate of stones, much soft mud.
View upstream, to the southwest.
At Borden Bridge on 5 July 2009, the community consisted of crayfish, large (2-3 inch) clams, Gomphid dragonflies, Pteronarcid and Isoperla stoneflies, Hydropsychid caddisflies , and the mayflies Isonychia, Ephoron, Hexagenia, many different Heptageniidae, and many different Baetidae. Pseudiron, Caenis, and Siphloplecton, found at Saskatoon the day before, were not collected at Borden Bridge.
For results of a thorough sampling of the site, see the Borden Bridge pdf on the River at Saskatoon page.
Some of the larval baetids in the video emerged to the subimago stage while they were in the collecting container. Mayflies have and extra stage in the life cycle, that is, egg, larva, subimago and adult. Other insects do not have the subimago stage. The individual in the picture is dull in color because it will moult one more time, shedding the subimago covering, and emerging as a shiny and bright adult. The individual in the picture is floating on the water caught by surface tension. Normally they fly away as a subimago and rest in trees or vegetation waiting for the final moult to the adult stage..
Notes #3 cont.
The family Baetidae has about a dozen genera and about 40 species in Saskatchewan, making it the largest in the Province. Many are of the "Baetid" type, being small - 5-10 mm- distictively coloured and each with unique features, but also requiring patience and skill to identify to the species level. I have not attempted to identify the specimens in the video at this time, but the purpose is to give an impression of their appearance in the collecting pan. See Ephemeroptera for lists and discussion.
Ephoron album (Say), Family Polymitarcidae(see also Ephemeroptera and the video) are small, about 1 cm in length, and the species can occur in huge numbers in muddy substrates in the river. At emergence time, adults appear in the millions, so that under the lights at ferry crossings, I have seen crusts and layers of dead adults 1 or 2 cm thick. Adults are attracted to lights, and they live only one day. They are considered by some to be "pests" but obviously they must be very important the ecosystem and food chain. They die after a night of emergence, mating, and laying of eggs. Adults serve the purpose of distribution, reproduction, and mixing of genes. They do not take food nor water, and do not even land on a solid surface. The legs of females are shrivelled and nonfunctional, and only the front legs of males are functional, being used to grasp females in mating. These are extreme examples of adaptation and an unusual life cycle.
The life cycle of larvae of Ephoron album were key to the evidence used in the paper on thermal regime alteration and the impact of dams and reservoirs on the river. Eggs and larvae also are adapted to specific environmental conditions. See Lehmkuhl (1972). They have been eliminated from many parts of the river, especially by dams.
Notes #3, cont
Mayflies of this family have flattened bodies, usually have conspicuous gills on the abodomen, they have legs which extend to the sides, and usually they have three but sometimes two long cerci, or tails. Eyes are on top of the head. These features can be seen in the video. The white individual in the video has recently moulted so that no color pattern is evident. A dozen genera and about two dozen species of Heptegeniids are found in Saskatchewan. I have not attempted to determine the identification of the specimens in the video. The point of the video is to show the habitus of members of the family. See Ephemeroptera for a list of species and discussion.
Members of this Genus (Family Ephemeridae) are the largest of all mayflies - two cm or more in length, and Hexagenia limbata (Serville) 1829, the species in the video, is found throughout North America. There are 5 species in the Genus. Hexagenia are found in lakes as well as rivers, and they are important as the base of the food chain for fish. Larvae burrow into the substrate, cause a water flow through the burrow by means of the wave action of the gills (see video) , and they filter and collect food as it passes through the burrow.
Isonychia campestris McDunnough (Family Isonychiidae, formerly in Family Siphlonuridae) ranges from the southwest US (e.g. Utah) to Saskatchewan. Close relatives extend into Mexico. The genus contains 16 North American species and most are eastern or southeastern. Larvae are large and robust for mayflies and can be found in great numbers in the Saskatchewan River, where they grasp a solid object and face upstream, filtering out organic material, or sometimes insect larvae according to some reports. They do this by means of two rows of long setae or hairs on the front legs, and it is these setae which are characteristic of the Genus and the Family. See the front legs being held forward from the body in the video. Lachlania (Oligoneuriidae, see Rare Species) have similar setae and habits, but the two are not closely related. Isonychia is not present downstream from Gardiner dam.
Siphloplecton, the species is almost certainly S. interlineatum (Walsh), but S. basale (Walker) also is found in Saskatchewan . The two species are separated by the presence of or lack of ventral flaps on gills 1-3. These were not checked in the specimen in the video. Siphloplecton, along with the genus Metretopus, make up the Family Metretopodidae, They are unusual and unique in that the front claw is bifid, split to near the middle, giving the appearance of two blade-like portions of the tip of the claw. The bifid claw separates members of this Family from the superficially similar Siphlonuridae and some Baetidae.
Note the "flickering" of the gills on the Siphloplecton in the video- a sign of oxygen stress most likely. Not all mayfly larvae can move the gills, e. g. the video of Pseudiron.
Also note the speeding Baetid flashing past, indicating the swimming powers of Baetis- type mayflies.
See related discussion, Baetids above
Larvae of most mayflies leave the bottom substrate and rise to the surface to emerge in the the air. This is the Siphloplecton larva in the video. It split the larval skin and the adult attempted to emerge, but was not successful. The right 1/3 is the larval cuticle, and the left2/3s is the partially emerged adult.
Pteronarcys dorsata Say (Family Pteronarcydae) is a large primitive stonefly found throughout North American and throughout Saskatchewan flowing waters. They are detritivores and when kept in an aquarium will skeletonize leaves that are provided as food. They require two or three years to mature as larvae. They are common and striking (see video) members of the river community.
Hydropsyche and Cheumatopsyche are common in the river, being abnormally abundant in nutrient and organically enriched areas. Species can be identified with patience and skill. They produce silk and construct a covering of stones over their bodies, attached to rocks, and they use silk to construct a filtering net outside the pile of stones which is their shelter. When collecting, one finds the exposed larvae in the collecting pan acting in the way that is showin in the video. Note the large number of white or transparent gills on the underside of the abdomen, and the "prolegs", the hooks at the end of the abdomen. The gills are represented by blackened areas in the photo on the Nuturents page.