Coastal Marine Environment
The Manuels River flows into the east side of Conception Bay; which is a significant recreation area for residents of the northern Avalon Peninsula having attractions such as boating, sailing, SCUBA diving, wind-sailing, and deep sea fishing for such species as cod, tuna and mackeral. Conception Bay also offers opportunities to view the conduct of inshore fisheries for lobster, salmon and capelin which all contribute to the experiential charm of the region. From the beach berm which isolates the coastal marine environment of Conception Bay from the estuary located at the mouth of the Manuels River, the seasonal migrations of three major groups of species are seasonally observable.
In early summer, whales, predominately the Humpbacked whale and the Finback whale pursues the abundant schools of spawning capelin into the coastal waters of Conception Bay.
Later in the summer and early autumn, the Pilot or "pothead", whale chases the squid into coastal waters in years when the squid populations are numerous and do migrate inshore.
A variety of other marine mammals may occasionally or rarely be seen from the Manuels River beach depending on the occurrence of appropriate environmental conditions. In late winter, the breeding populations of harp and hooded seals are occasionally observable on southward drifting ice floes in Conception Bay.
During the early winter, prior to the arrival of coastal and drift ice, varieties of sea birds such as eider ducks, guillemots, murres, etc. may be seen from Manuels River beach. Other common coastal species which frequent the area are the species of gulls and terns which nest on islands in Conception Bay just off the coast in this area.
Manuels River Estuary
Between the river mouth and the beach barrier berm is an area known as an estuary. This area is interesting due to the gradient of salinity encountered as one gets closer to the sea and its tidal influences. Consequently, the species which are able to live within this fluctuating salinity environment are tolerant to a variety of environmental conditions. These tolerant species do, however, have the opportunity of taking advantage of the higher nutrient value characteristic of estuaries and constitute a diverse variety of species which inhabit the estuary.
The Manuels River estuary area collects a considerable quantity of nutrients from natural and man-made sources which are flushed down the river. In addition, the estuary receives some nutrient input through the tidal waters which invade it; particularly in the lower (seaward) reaches of the estuary. This increased nutrient input results in higher primary productivity in phytoplankton and bottom-attached abundant aquatic algal growth. The abundance of this planktonic and attached algae fosters the growth of a large population of small invertebrates, most obvious of which are brackish and freshwater shrimp or amphipods, which are primarily scavengers. These small shrimp-like creatures are potential prey items for trout species found in the river, which seem to congregate in the pools down near the river mouth. The estuary is also home to a variety of interstitial or sub-bottom dwelling animals which are highly tolerant to salinity fluctuations, such as annelid, polychaete and nematode worms. Occasionally, marine animal species such as capelin or lobster may invade the estuary on high-rising tides.
The slow-moving, deeper river water in this estuary harbours a luxuriant growth of various water weeds (e.g. potomogeton and myriphyllum). This protective habitat supports a large number of three-spine and four-spine sticklebacks. Male stickleback may be observed in their breeding colours (bright blue body, deep orange-red eyes) in early to midsummer indicating that there is suitable habitat for these fish to build and maintain the nests in which the fertilized eggs are laid and defended. These fish spawn generally in July, with the males defending a nest site and guarding the eggs. Some young-of-the-year sticklebacks may be observed further up the river in fresh water environments.
Manuels River Delta Islands
The mouth of the river flows into the estuary and upstream through the region where the river is broad and flat. In this area, siltation has caused deposits to form a classic delta which comprise a group of delta islands and the sinuous meandering of the flowing river through these islands. These islands constitute a very fertile natural garden which contains an abundance of wild flowers such as blue flag iris, wild rose, common vetch, ox-eye daisy and buttercup, as well as luxuriant summer growth of rushes and grasses. The delta islands are therefore special in their plant diversity and the sheer magnitude of flowering foliage which covers them. This habitat also provides sheltered homes for a variety of small birds including white-throated sparrows and hermit thrush which serenade the area from the undergrowth along the river. The fertile beaches of the delta island and nearby river banks are good feeding grounds for spotted sandpipers. Gulls are also present. Water lilies grow in the quieter pools and the ectoskeletons of emergent mayflies can be observed on the lily pads.
Inland of the Conception Bay Highway Bridge
The bridge over the Manuels River at the Conception Bay Highway marks the beginning of a different habitat composition for aquatic biota as a consequence of the change from the geologically later formed sedimentary and metamorphosed rock formations below the bridge to the harder granitic and igneous rock found above the bridge. Consequently, the erosive forces of the river have not penetrated these harder rock formations as successfully as in the region below the bridge. Consequently, the physical environment available to biota above the bridge is dramatically different that below the bridge. This causes some shifts in plant species assemblages and faunal composition; all contributing to the diversity of topography and life forms which may be observed on the Manuels River system.
The shallow pools and riffles in this location are home to an abundance of aquatic invertebrates and two stickleback species. Mayfly and stonefly larvae are found hiding under rocks in the faster-flowing and more oxygenated riffle areas. Two major types of case-building caddisfly larvae may be observed those which build their cases out of pebbles and which live secured beneath rocks in the flowing waters of the river, and those that make their cases out of twigs and which can be observed crawling over rocks in quieter pools, grazing on algae. Chironomid larvae, which can live in less-oxygenated water, are found in the muddy areas. In this section of the river are leeches and their gelatinous egg cases hidden under rocks. Flatworms, a major prey item of the leeches, are found in great abundance under the rocks and in pools formed in the hard bedrock formations of the river. Numerous dragonflies and damselflies may be observed flying about over the river from mid-July and indicate that the aquatic larval forms of these insect species would be found in the river earlier in the summer. A variety of wild flowers such as asters and shrubs such as bog laurel, common shrubs such as the alder are present along the banks of the river in this area.