Archive for Aquatic Life
This is an excellent film! A must see!
Become a Local Expert
Because of their constant filtering, Unionids are the heavy-duty in-stream providers of “water quality,” and unlike fish, they can’t get out of the way and then quickly swim back to recolonize a site. Stream projects should avoid disturbing the streambed where they’re abundant, since the mussels mature slowly, and mature individuals can keep providing improved water quality for several decades. Water level fluctuations in impoundments can make
vast areas of the bottom behind dams uninhabitable.
To become the local unionid expert, search shores & bottoms of streams, and shores & shallows of lakes, concentrating on clear-water habitats and on riffles, and especially on streams right below lake outlets, where phytoplanktonic food from the still water flows like a perpetual buffet. Some species are wedged into the mucky banks of streams. Muskrats accumulate shell piles beside stumps and rocks on the bank, which you’ll find easily once you begin to think like a Muskrat. Flood waters concentrate shells at the foot of bars, or in eddies. It’s important to examine lots of animals and collect lots of shells, because many species are superficially hard to tell apart and many are rare. Since you can collect dead shells without harming the populations, it’s possible to gather material documentation of the occurrence of species, and their variation.
Kerr, S. J., M. J. Davison and E. Funnell. 2010. A review of lake sturgeon habitat requirements and strategies to protect and enhance sturgeon habitat. Fisheries Policy Section, Biodiversity Branch. Ontario Ministry of Natural Resources. Peterborough, Ontario. 58 p. + appendices.
Pages 4 to 8:
The decline in lake sturgeon across much of North America has been attributed initially to unregulated fisheries and, more recently, to habitat alteration and destruction notably by pollution, dredging and channelization, and the construction of dams and hydroelectric facilities. Dredging and channelization can alter lake sturgeon spawning grounds. Sturgeon have been impacted by many forms of pollution which can disrupt olfactory feeding behaviour. Dams and hydroelectric stations can have a negative impact on lake sturgeon by fragmenting their habitat, impeding migrations to spawning grounds and, depending on the type of operation, having a negative impact on egg survival and recruitment. Downstream migrants may also be impinged or entrained at hydroelectric plants.
Attempts to resolve some of these habitat impacts have included construction of fish passes at dams, establishing base flows or “run-or-river” regimes at hydroelectric facilities, creation or enhancement of spawning areas, use of downstream guidance and diversion structures, and improvements to water quality. There has been some success with constructing artificial spawning grounds for lake sturgeon. Sturgeon have also been shown to display a positive response to improvements in water quality and “run-of-river” hydrologic regimes at dams and power stations. The ability to design a fish pass suitable for fish with the body size/shape and swimming capabilities of lake sturgeon has proven difficult, however, and further research is required in this area. Many sturgeon populations are also impacted by “peaking” operations at hydroelectric facilities and the issue of facilitating downstream passage over artificial barriers also needs to be resolved. Read More→
Author: MacGregor, R., J. Casselman, L. Greig, W. A. Allen, L. McDermott, and T. Haxton. 2010. DRAFT Recovery Strategy for the American Eel (Anguilla rostrata) in Ontario. Ontario Recovery Strategy Series. Prepared for Ontario Ministry of Natural Resources, Peterborough, Ontario. vii+ 78 pp.
Pages 23 to 24:
Barriers to Migration
Dams can severely impede upstream dispersal of juvenile eels in freshwater if no passage way is provided (Haro et al. 2000). It has been estimated that 85 percent of freshwater habitat for migratory fish in the United States has been lost due to barriers (Lary et al. 1998). In a 1998 study, the U.S. Fish and Wildlife Service determined that eels may have been eliminated from 81 percent of their historic habitat between Connecticut and Maine due to the construction of a large number of dams (ASMFC 2000). Barriers reduced eel densities by at least a factor of 10 on the Hudson River, and eel condition was significantly poorer above barriers (Machut et al. 2007). The situation appears similar in Ontario where at least 953 dams exist within the eel’s historic range (Figure 7). Hydroelectric dams generally pose the most significant barrier to upstream migration due their height. However, with the exception of one eel ladder at the Moses-Saunders facility on the St. Lawrence River, as of 2008 no provisions for upstream fish passage for any species have been made at any of the approximately 200 hydroelectric stations in Ontario. Negotiations with a few facilities are now underway to correct this situation for upstream eel passage.
Turbines at Hydroelectric Facilities
Hydroelectric facilities in Ontario pose significant challenges to eels (Larinier and Dartiguelongue 1989; Mitchell and Boubée 1992; Desroches 1995; Normandeau Associates Inc. and Skalski 1998; Haro et al. 2000; Dönni et al. 2001, in ICES 2003; McCleave 2001; Allen 2008 b, c, d), as they impart serious individual and cumulative mortalities at the watershed level to downstream migrants en route to spawn (McCleave 2001; MacGregor et al. 2009). There are 87 hydroelectric facilities within the historic range of eels in Ontario, and 30 within the post-2000 range (Figure 8). As of 2009, many of these facilities continue to cause annual eel mortalities (Community Stewardship Council of Lanark County 2010; A. Bendig, pers. comm. 2009; K. Punt, pers. comm. 2009). With the exception of recent trap and transport efforts at Moses-Saunders, mortalities due to turbines at all hydroelectric facilities in Ontario continue unmitigated on most watersheds. Read More→
Author: Ontario Ministry of Natural Resources. 2009. The lake sturgeon in Ontario. Fish and Wildlife Branch. Peterborough, Ontario. 48 p. + appendices.
The construction of dams, many for hydroelectric power generation, restrict access to spawning, nursery and feeding habitats thereby fragmenting their natural habitat (Figure 12). Hydroelectric development was identified as the greatest problem for
lake sturgeon rehabilitation at 12 of 21 historic Lake Superior spawning sites (Ebener 2007). The blockage of migration routes has been attributed as the cause for decline and a factor preventing recovery of lake sturgeon in many situations (Harkness and Dymond 1961, Haxton and Findlay 2008, Mohr and McClain 2001, Swainson 2001).
Hydroelectric power generation can have strong negative effects on sturgeon spawning downstream. Sturgeon recruitment is believed to be related to the volume of spring water flows. The artificial alteration of water levels and flows disrupts the natural
environmental cues associated with movements, spawning and downstream drift of larval fish. Constant flows allow large fish migratory access and triggers reproduction resulting in less time spent on the spawning grounds (Auer 1996b).
On the Kaministiquia River, Friday and Chase (2005) reported that adult sturgeon did not move to the spawning area at the base of Kakabeka Falls until flows reached 23 m3 sec-1. Water level fluctuations below dams can leave eggs susceptible to dessication (Brousseau and Goodchild 1989, Evans et al. 1993, Rosenberg et al. 1997). In some cases, sturgeon can become entrained and
stranded in pools downstream of hydroelectric facilities (Seyler 1996). Download complete Report.
Author: Golder Associates Ltd. 2011. DRAFT Recovery Strategy for Lake Sturgeon (Acipenser fulvescens) – Northwestern Ontario, Great Lakes-Upper St. Lawrence River and Southern Hudson Bay-James Bay populations in Ontario. Ontario Recovery Strategy Series. Prepared for the Ontario Ministry of Natural Resources, Peterborough, Ontario. v + 74 pp.
About the Ontario Recovery Strategy Series
This series presents the collection of recovery strategies that are prepared or adopted as advice to the Province of Ontario on the recommended approach to recover species at risk. The Province ensures the preparation of recovery strategies to meet its commitments to recover species at risk under the Endangered Species Act (ESA) and the Accord for the Protection of Species at Risk in Canada.
1.6 Threats to Survival and Recovery
A number of factors have contributed to the historical decline of Lake Sturgeon. Current threats include habitat alteration and fragmentation, pollution, illegal harvest, exploitation, species invasions and climate change (Harkness and Dymond 1961;
Rochard et al. 1990; Birstein et al. 1997). These threats must be addressed in order to achieve recovery of Lake Sturgeon in Ontario.
The loss of habitat that occurred beginning early in the twentieth century is considered far less important than overfishing in contributing to their precipitous decline. In fact, many of the populations were reduced to remnant populations prior to major
environmental perturbations affecting Lake Sturgeon habitat, including dam construction in Ontario. The combined impacts of habitat loss, overexploitation, increased industrialization, pollution, and species invasions make it difficult to establish current
cause and effect relationships in Lake Sturgeon populations.
Habitat Alteration and Fragmentation
Lake Sturgeon is a long-lived, migratory species that requires distinct habitat types throughout its life cycle. Habitat suitability may be constrained by the management of water levels, river flows, the creation of dams and by food availability. Where a
particular life history stage occupies or congregates in discrete locations, they become more vulnerable to localized disturbance.
Studies on the Ottawa River indicate that Lake Sturgeon distribution, especially of juveniles, is positively correlated with unimpounded river habitat (Haxton and Findlay 2008). The Moose River basin is one of the most fragmented river systems in North America. The overall and cumulative impacts on the region’s Lake Sturgeon subpopulations is unknown (Seyler 1997a). However, Lake Sturgeon have been impacted in discrete sections of rivers that have been impounded (Gibson et al. 1984; Nowak and Hortiguela 1986; Payne 1987). In these cases, the effects of habitat alteration due to historical log drives (e.g., bark deposition and scouring) and dam construction (e.g., loss of riverine habitat and fragmentation) as well as overfishing contributed to localized declines in abundance and eventual recruitment failure.
Many hydroelectric dams were historically constructed at natural barriers on rivers (e.g., waterfalls), where the greatest potential to build hydraulic head and to generate power existed. The fast flowing habitat below these features likely represented spawning habitat for fish species such as Lake Sturgeon. Where dam construction has created artificial barriers to upstream migration and disrupted formerly continuous habitat, Lake Sturgeon sub-populations have become fragmented (Wozney et al. 2010; Wilson et al. in prep.). Despite the construction of barriers, Lake Sturgeon will spawn at the base of dams (Auer 1996b; Haxton 2006). In such cases, flow management to provide access to and from spawning habitat, the provision of suitable spawning substrate and suitable flows to facilitate hatching and larval drift is critical. Download complete Report.
Author: Wilton, M.L. 1985. Water drawdown and its effects on lake trout (Salvelinus ncmayaush) reproduction in three south-central Ontario lakes. Ont. Fish. Tech. Rep. Ser. No. 20: iii & 9 p.
Observations and data gathered from Bark Lake indicate that reproduction of lake trout (Salvelinus namaycush) is no longer possible because of water drawdown of as much as 10 m annually. The fishery is now sustained by hatchery plantings. Data and observations from Mary Lake indicate that natural reproduction of lake trout may be severely curtailed at one of two shoals due to winter drawdown of as much as 0.83 m. Bella Lake has no dam or water level drawdown. Spawning occurs in less than 0.3 m but ice thickness lessens toward shore and as a result, there is no egg loss.
The area located between the Ottawa Valley and Georgian Bay, south of the French and Mattawa Rivers and north of the Kawartha Lakes, contains many oligotrophic lakes which provide suitable environments for lake trout (Salve-1-inus namayaush’) • Water control structures at the outlets of many of these lakes regulate water levels for hydroelectric generating stations downstream, as well as for cottage and recreational demands. Water drawdowns in these lakes characteristically occur during late fall and winter and coincide with the incubation period of lake trout eggs. The purpose of this paper is to document observations on lake trout spawning and water drawdown in three of these lakes. Download complete Bark Lake Study, by M.L. Wilton.
Environment Canada. 2001. Threats to Sources of Drinking Water and Aquatic Ecosystem Health in Canada. National Water Research Institute, Burlington, Ontario. NWRI Scientific Assessment Report Series No. 1. 72p. Page 69 – 15. Impacts of Dams/Diversions and Climate Change; T.D. Prowse,1 J.M. Buttle,2 P.J. Dillon, 2 M.C. English, 3 P. Marsh, 1 J.P. Smol4 and F.J. Wrona1; 1Environment Canada, National Water Research Institute, Saskatoon, SK; 2Trent University, Peterborough, ON; 3Wilfrid Laurier University, Waterloo, ON; 4Queen’s University, Kingston, ON. Full document available.
Below is an excerpt:
“Most of our current knowledge of the impacts of water quantity changes on water quality is based on studies of the effects of Canada’s more than 600 dams and 60 large interbasin diversions, which makes the nation the world leader in water diversion (Day and Quinn 1992). Most Canadian dams store water during peak flow periods and release flow to generate power during winter, low-flow periods.
Such changes to water quantity also modify various water quality parameters within the reservoir and downstream, the effects decreasing with distance from the impoundment. Major examples include:
- thermal stratification within the reservoir and modification of downstream water temperatures
- promotion of anoxic conditions in hypolimnetic water and related changes in metal concentrations in outflow;
- increased methylation of mercury;
- sediment retention;
- associated changes in TDS, turbidity and nutrients in the reservoir and discharged water;
- increased erosion/deposition of downstream sediments and associated contaminants.
For impoundments used for drinking water, intra-storage processes also have serious implications for the quality of drinking water.”
Scientists studying lakes in northern (Lake Superior) and tropical latitudes are finding that rising lake water temperatures are affecting the ecosystems of the lakes.
Credit: NBC Learn and the National Science Foundation (NSF)