Author Archives: Dr. Pedro M Pereyra

About Dr. Pedro M Pereyra

I am an organic chemist and neurobiologist by training, and a naturalist by passion. My experience in these areas forms the foundation for my present research in ecosystem function. My scientific interest also informs my work and approach as a chemistry and environmental sciences high school teacher. My research and teaching is also guided by my interest in history and the arts. In my work I use photography both, as a documenting medium, as well as, an eastetic form complemented by poetry and short stories,

Notes on future updates and posts

It was November 2014 since my last note.  Too long ago. And much needs updating and publishing

Already prior to 2014 I have been monitoring vernal pools and herpetofauna in a number of sites other than Neyagawa-NHS and the 14 Mile Creek (both in Oakville). All monitoring results and community , water chemistry and plankton observations in this area are going to be organized as webpages by site under the general heading of “Vernal Pools & Herpetofauna“. I hope all the results up to December 2015 will up in the next few weeks.

In my surveys, many times, I find changes in the state of habitats and communities due to anthropogenic or natural events which are important to log as part of the history of the sites affected. These entries will be collected under the general heading “Site Survey Notes“.

Exiting blog entries will be expanded or copied into these new webpages. Blogs will be used for brief updates before they form part of the main website stream.

Areas of Concern at the Neyagawa NHS site applicable to other NHS areas

On August 2014 I was able to meet with Frank Laconte and Kristina Parker at the Town of Oakville. The meeting was facilitated by Mark Chris -. Director of the Parks and Recreations Dept. of the Town of Oakville.

In that meeting I submitted the following presentation. Note that the Google images used in the presentation  can not be printed or further distributed. Anyone interested in the details can request the .kmz files for further analysis (For security reasons .kmz files can not be downloaded to WordPress).

Conservation and Enhancement of NHS Hydrological Features locked

The mapped overlays, as far as the extent of the specifically designated vegetation/tree boundaries are concerned, are close to mapped and measured locations, but nonetheless approximations.

The areas of concern are summarized over the boundary map of the Neyagawa Site of the NHS submitted in the North Oakville Subwatershed Study that forms the basis of the boundaries and alignments of the development sites with the NHS.

Scanned from Conservation Halton with comments

 The boundaries in the zone closer to 6th line (right side of the map) have certainly not been properly implemented, perhaps there is the chance of some enhancement of the boundaries around the central area of concern where they missed to identify a MAM containing the fire bush  that connects the SWD at the time this boundaries were laid out. Plus, this is the area where the vernal-autumnal pond is located. One can hope to negotiate for the trail to be on the outside of the treeline to safeguard these features. (edited excerpt of correspondence with Conservation Halton).

 We will have to wait to see what Conservation Halton, the developers and the Town will eventually produce and if it  will have any resemblance to the promises made during  the North Oakville Trail Plan consultations.


Pond # 1… Spring 2013 visit of the amphibian breeding pond

Vernal Pool Spring 2012

Vernal Pool Spring 2012

This year’s visit to this amphibian breeding pond helped consolidate the presence of several invertebrate species, as well as, serve as an indication of the variability of the number and kind of species making use of the spring conditions of this vernal pool.

Pond characteristics and surrounding vegetation


Figure 1. Vernal pool dimensions

The longest axis of the vernal pool has a west-east alignment measuring 28m. it is pear-shaped with a maximum width of 15m to the west and 12.7m to the east; and about 12m in its shortest width (see Figure 1, north upwards ). Water depth at maximum fill reaches about 60 to 80cm deep about 1 to 1.5m off its southern edge (see Figure 2, image rotated counter-clock wise). On may 11, depths measured were only around the 60cm to 40cm. The muck and leaf detritus layer is in the range of 25cm on the western edge to 17cm on the eastern edge. The underlying mineral soil layer below the muck is made of a heavy glay clay (Glay1 8/N) containing only a very small proportion of sand and gravel and less than 1% clay mottles. Also shown in Figure 2. is the few location of submerged grass.

Figure 2. Sketch of contour of the pool along the cut in the picture including measurements of water and muck depth to clay layer. Notice in the picture the location of submerged vegetation in the pool.

Figure 2. Sketch of contour of the pool along the cut in the picture including measurements of water and muck depth to clay layer. Notice in the picture the location of submerged vegetation in the pool.

Figure 3 (north is up). maps the location and characteristics of trees, shrubs and forbs within 5m of the vernal pool. Of significance is the presence of two elms(probably Rock Elms Ulmus thomasii) with bdh of 40 to 50cm and 16 to 20m high. Elms this tall are very unusual. A cluster of young Rock elms – with bdh in the range of 10 to 15 cm, are growing in the proximity of these two older elms. Why these group of elms has remained unaffected by Dutch-elm disease is unclear, when just less than 100 meters to the west, clusters of dead elms attest to the effect of the elm disease. Notice the encroachment by ash and maple on the south-eastern bank of the pool.


Figure 3. North is up. Identification of major mature trees visible on the aerial picture and views of marked locations. The vernal pool is essentially framed by three distinct tree populations: Poplars to the northeast and east, Elms to the north-west and west and Silver Maple, White Ash and Sugar Maple mix to the south, The invasive Buckthorn (Rhamnus cathartica) to the north and Barberry (Berberis spp.) o the south are the main shrubs at the banks of the pool.

Account of species detected on April 21 2013 (visual survey)

Amphibian tadpoles: fewer overwintering Green frog tadpoles (~100mml; Lithobates clamitans) were observed this spring compared to last year.


Overwintering green frog (Lithobates clamitans) tadpoles



  • This year, at least two, if not three species of amphibians laid eggs in this pool.


One of the egg masses groups among the submerged plant clusters located on the northern edge of the pool.

Most abundant eggs masses were from, what seems to be, Wood frogs (Lithobates sylvatica).

Characteristic Yellow-spotted salamander egg masses (Ambystoma maculatum, white eggs in the early stages – acquiring symbiotic bacteria later in their development) were also laid close by or mixed with the frog egg masses. [Top picture taken on April 21st, bottom picture taken in May 7. Notice in the bottom image the snail on the lower edge to the right of center (possibly Radix auriculata)].



Small isolated egg mass with only a few large eggs without gelly capsule were also noticed. These egg masses were laid in more shaded areas and apart from all others. They could be blue-spotted salamander eggs (Ambystoma laterale).


Small cluster of large eggs. Possibly from Blue-spotted salamander

  • Like last year, Central Newts (Notophtalmus viridescens lousianensis) were also noticed in the pool.


    Central Newt (Notophtalmus viridescens louisianensis)

  • A predaceous diving beetle (Dysticus spp.) drawn to a cluster of gray velvet springtails of the Poduridae family.

Notice the springtails on the lower right of the image.

  • Only one occurrence of a large aquatic snail (?Radix auriculata) was noticed this year – compared to their relative abundance last year (see the Yellow-spotted salamander image above). Relatively large (about 10 to 20mm in diameter) snail egg sacs were found at the east end of the vernal pool. Last year’s egg sacs were smaller but were more frequently found.

About 1 to 1.3 cm on diameter snail egg sacks.

Account of species detected between May 7 and May 11 2013.

  • One adult Green frog (Lithobates clamitans melanotus) seen on May 7.

Green frog (Lithobates clamitans malanotus)

  • On May 11, a benthos sampling was performed. On surveying the location before and after benthic sampling, the following species were seen in the floating and submerged water layers:

Central Newt larva (see image below) and Central Newt adult (Notophtalmus viridescens louisianensis)


Swimming among the overwintering Green frog tadpoles was a number of smaller dark blackish tadpoles (~40mm; possibly wood frog tadpoles).

A variety of aquatic snails were found foraging on submerged and floating tree trunks and branches. Two kinds were seen: medium size (~1cm long) with pointed conical shells (Stagnicola spp.?), and flat coiled with ridges only a few millimeters in diameter. Also noticed was a large number of small gelly spherules on the mosses (?eggs).


snail activity on the underside of floating or submerged wood

Dobsonfly larva, Hellgrammite (~25 to 30mm) on underside of a submerged branch (Corydalus spp.). An indicator of relatively pure and undisturbed conditions.



  • Benthos Sampling results: Will be reported in an upcoming blog entry

Account of species absent in the 2013 survey compared to the 2012 spring survey.

  • This spring there was no indications of the following species:

Leopard Frogs(Lithobates pipiens)

Midland Painted Turtles (Chrysemis picta marginata)

Water conditions for this spring

DATETEMP ('C)BANK SOIL TEMP ('C)pHCONDUCTIVITY (uS/cm)ORP (mV)Alkalinity (ppm)Phosphate (ppm)Nitrate (ppm)Hardness (ppm)Turbidity (FTU)
21 April 2013857.3245182110>4nd25084.7
11 May 2013148.1340175<1nd5.92?


Pond #1 “… in a drop of water”

The following images represent some of the organisms recorded in a 500mL water sample colleceted on March 25 from the littoral water and leaf litter of Pond #1. It also includes organisms photographed during the survey but not collected.

The pictures are organized Taxonomically:

Hydrozoa: Hydra spp. – 3 to 12mm long

Gastropods – Finger-nail clams (Spheriidae) – 2 to 7mm long






Molluscs: Water snail – 20mm long







Arthropods are represented in this pond by the Crustaceans Orders: Cyclopoda, Ostracoda, and Amphipoda, as well as, the Hexapod Orders: Adephaga, Mixophaga and Polyphaga Coleoptera, Hemiptera, and Ephemeroptera.

Crustaceans- Cyclopoda – Cyclops spp. – 0.1 to 0.5 mm

Amphipoda – Scud – Hyallela azteca complex – 5 – 7mm

Ostracoda – Podocopidae – 0.2mm long







Several egg masses were found attached to the leaf litter in the pond. These egg masses varied in appearance and texture as well as, in the size of the eggs it contained. The eggs in the water sample were observed from the day they were collected on March 25 until April 27. The water sample was kept at 13C to 16C and exposed to daylight through a window located two meters away from the sample.

1) Two translucent ochre single layered plastic cartouches with egg chambers about 1mm in diameter were found attached only to oak leaves. These eggs were the first ones to develop into recognizable morulae by April 4. Species unknown.

cartouche illuminated from the top (25.iii.2012)







Morulae after 20 days (04.iv.2012)


recognizable snail embryos two days later (16.iv.2012)





well-developed snail before hatching (21,iv,2012). By April 24 all snails had hatched.

Neyagawa Forest System Species Inventory

The attached Acrobat pdf file (Table of Species), contains a list of Trees, Shrubs, Forbs, Ferns, Grasses, Sages and Fungi identified at the Neyagawa Forest System between 2010 and 2012.

The identification of some shrubs is tentative, the sage and grass species are incomplete, and that of Fungi needs to be verified.

Polygons refers to the way the forest system was subdivided for study purposes. These polygons partially correlate with specific forest types and post disturbance stages.

Amphibians & Reptiles of Neyagawa


Survey 2012 to 2013


Spring Peepers Pseuacris crucifer





Leopard Frog Lithobates pipiens




Tadpoles (approximate 70 to 75mm long); very possibly overwintering L. pipiens tadpoles.








Red-spotted Newt  Notophtalmus viridescens viridescens






Red-spotted Newt  Notophtalmus viridescens viridescens




Midland Painted Turtle Chrysemis picta marginata




Midland Painted Turtle Chrysemis picta marginata





Eastern Garter Snake – Thamnophis sirtalis sirtalis

Water quality measurements

The water quality factors measured were pH, alkalinity (ppm, indicates buffering capacity), hardness (ppm, indicates content of polyvalent cathions), TDS (ppm total dissolved solids, indicates ions in solution)

POLYGON & LOCATIONpHAlkalinity (ppm)Hardness (ppm)TDS (ppm)Water Temperature (C)
Polygon I, WP 68b (Main stream) MARCH 25680200615nd
POLYGON I, WP 52 (VERNAL) MARCH 14520100ndnd
POLYGON I, WP 12 (VERNAL) MARCH 14520100253 TO 6
POLYGON I, WP 38a (VERNAL) MARCH 144.520100255
POLYGON 1, WP 47 (POND#1) MARCH 14540100775
POLYGON 1, WP 47 (POND#1, rain fed only) MARCH 256802501567
POLYGON I, WP 72 (FEN, central sage swamp) MARCH 145402001427
POLYGON III, WP P2 (POND#2) MARCH 2561008080nd
POLYGON III, WP P3 (POND#3/MARSH)620<50130nd
POLYGON V, WP 72 (BROOK, marsh draining stream) MARCH 235<20<5038nd


Spring 2012 faunal survey

Observations made during Jefferson Salamander breeding period in a very early spring with unusually high temperatures and after a very mild winter with rain rather than snow fall.

14, 23 & 25 March 2012 observations:


  1. Vernal Pools:
    1. No evidence of salamander egg masses in any of the vernal pools.
    2. Noticed the presence of a finger-nail clam species (Spehariidae) in vernal pools close to Neyagawa Road west of the Neyagawa Forest stream (broadly flooded by stream and road runoff). No evidence of clams was noticed in all other vernal pools (that doesn’t mean they are not there). These clams were present in ponds – see below.
  2. Rain fed only ponds
    1. Pond #1 – Located  in the forest close to the eastern edge of the forest at WP 47,
      1. March 14: the presence of at least 30 or more relatively large tadpoles at a prehind leg stage.
      2. March 25: two tadpole captured and measured. 70 – 75mm long, 27 – 30mm body length, 42 – 43mm tail length, 15 – 18mm body width, and 10 – 12mm body hight.
        1. The tad poles might be hibernating Green frog tadpoles (Lithobates clamitans) (too small to be bull frog tadpoles at the same stage?).
      3. March 25: Basking single individua of
        1.  Leopard frog (L. pipiens) and
        2. Spotted turtle (Clemmys guttata; endengered)
      4. March 25: Water snails (not yet identified), Water-striders (Gerridae), Backswimmer bug (Notonectidae), Predaceous Diving beetles (Dysticidae), and a few Whirling beetles (Gyrinidae).
    2. Pond water sample including leaf litter taken from the southern edge of the pond ~500mL.
      1. Examination of the sample between March 25 and April 5 revealed the  presence of :
        1. Finger-nail clams (Spehariidae)
          1. three specimens ranging from 2mm to 7mm in length.
          2. by April 2nd/3, 3 more small clams have been observed, probably buried in the muck now large enough to become evident (1.5 to 3mm)
          3. April 5, all clams collected and stored in 70% Isoporopanol.
            1. 7 small calms (2.1 to 2.4mm)
            2. 2  larger clams (5.8 and 7.4mm)
        2. Active Podocopid Ostracoda (one or two possible species, 0.2mm long)
          1. by April 3rd, specimens detected rangefrom about .5mm to 2mm.
          2. evidence of empty shells keeps increasing with the passing of days
          3. April 3rd, observed one less then a tenth of a mm specimen.
          4. April 4, pictures of a shell showing the muscle scar pattern consistent with the specimen belonging to the Cypridacea superfamily and possibly of the genus Paracypris spp.
          5. April 5, two specimens collected (~1mm)
        3. Small-Minnow-Mayfly larvae (Callibaetis spp.)
          1. 6.5mm long; two such larvae in the sample
          2. by April 2nd, both have molted once and are reaching 7 to 8mm
        4. Freshwater shrimp (Amphipoda, Hyallela azteca complex)
          1. one light ochre specimen in the sample ~5 to 6mm (has a characteristic black rings in the base of the last antennal segment of the anterior pair).
          2. by April 2nd, the specimen has molted once and has become of a darker grayish colour.
          3. a second specimen found by April 3; same size as the first one.
        5. Hydra (Hydrozoa, Hydra spp.)
          1. green specimens with 5 tentacles, a total of 3 specimens observed
          2. by April 2nd, one specimen has a younger budding one on its side.
          3. by April 3rd, this specimen has moved about 6cm to a new location
        6. Green spheroid “cysts” unidentified
          1. 5 to 6 such globules
          2. by April 2nd, only 3 are left
          3. by April 3rd, only one left
        7. Jelly masses (two, a few cm long) consisting of ~1 mm transparent eggs with a white aggregate in the centre.
          1. no appreciable change in the eggs by April 2nd
          2. by April 3rd, one of the egg masses contains an active prodding translucent plychaete about 2 to 2.5mm long with pairs of long seate. (Bristleworm)
          3. no rotating motion was noted in the egg’s central aggregate
        8. Hard translucent moulded amber casing containing a layer of eggs ~ 1mm transparent eggs with a white aggregate in the centre.
          1. no appreciable change in the eggs by April 2nd
          2. by April 3rd, the center was filmed showing slow rotations that were consistent with a blastula
        9. One golden Pigmy Backswimmer (Pleidae, Neoplea striola)
          1. April 3rd, a highly conves golden coloured 2mm backswimmer. Its silvery abdomen consistent with air trapped in its abdominal surface.
          2. Identity confirmed April 5.
        10. Cyclopoids. Abundant in the sample. Possible two to three different species.
          1. A cycle of abundance and diminishment noticed for these small crustaceans.
        11. Protozoans. Abundant in the sample
        12. Blue-green Algae. Closteriaceae, Closterium spp. First specimen observed April5.
  3. Runoff and rain fed ponds
    1. Pond #2 (in the open pond located close to the eastern edge of Polygon III at WP P2).
      1. March 25: the presence of at least 20 or more relatively large tadpoles at a pre hind leg stage.
      2. March 25: No egg masses detected in the pond. March 25: Presences of at least 2 newts (Red transforming or Central newt; Notophthalmus viridescens).
      3. March 25: Water snails (not yet identified), Water-striders (Gerridae), Backswimmer bug (Notonectidae), and a large colony of Whirling beetles (Gyrinidae).
  4. Marshes with open water fed by runoff and rain
    1. Central Fen/Marsh in Polygon I at WP 72.
      1. March 14: Except for bacterial “clouds” there was no evidence of amphibian activity.
      2. March 25: Identification of an ant hill within the swamp.
      3. March 25: still no evidence of any amphibian activity.
    2. Polygon V. Marsh complex
      1. WP 74.  Slow draining brook off the marsh in Polygon V.  Mud chimneys. Non was taller than 2 to 3 inches. Central tube diameter ranges from 15 to 25mm. Two species are possible the Devil Crayfish (Camburus diogenes) or the Digger Crayfish (Fallicambarus fodiens). The habitat of both these species is threatened.
      2. WP 75 3 to 5 Chorus frogs (Psuedacris triseriata) heard in the marsh. WP 76 (boundary of the marsh with the open field to the south east). Evidence of a crayfish chimney.
      3. WP 79 (south edge of the marsh boundary with remnant tree line. Evidence of Spring Peeper (Pseudacris cruciifer).