GREATER FUNDY ECOSYSTEM RESEARCH PROJECT

UNB Faculty of Forestry and Environmental Management

State of the Greater Fundy Ecosystem

The State of Aquatic Ecosystems

Douglas Clay
Fundy National Park
P.O. Box 40, Alma, N.B.
E0A 1B0

Aquatic ecosystems are more sensitive than terrestrial systems to short-term climatic effects, particularly precipitation. Small forest streams can disappear completely during periods of drought (see Clay and Butland, this volume). Within Fundy National Park (Fundy NP) the long-term precipitation is seasonally stable with a slightly higher amount falling in the autumn and winter months. However, inter-annual variation can be significant. In the last decade the mean annual precipitation has increased over 10% from the previous 40 years, although the summer rainfall during this same period appears to have declined. How this might affect the aquatic systems is uncertain.

AQUATIC SYSTEMS

In Fundy NP there are two major freshwater aquatic systems, each extending outside the park. The systems are the Point Wolfe River (143.6 km2) and the Upper Salmon River (181.8 km2) and their associated watersheds and tributaries. Within each is a wide range of habitat diversity, however, a serious loss of ecological integrity has occurred within these aquatic ecosystems (Cooper and Clay, this volume). River driving of logs by the lumber industry in the last century has removed large woody debris and other natural obstacles, eroded the river banks, and probably degraded aquatic communities. It has also created areas of unstable banks on the sites of old ‘brows’ that were used for loading the river with logs. Major land slides have occurred in recent years on these sites.

The Point Wolfe River (Photo: A. Skibicki)

Forest harvesting practices employed since the end of the river driving era require extensive road networks to transport logs. These roads, and associated ditching, increase the size of the drainage area for surface runoff that enters natural river systems. Both of Fundy NP’s major river systems have over 1 km of stream per km2 of watershed. The highway and forest road network surrounding the park (within a 15 km buffer) has 0.93 km of roadway per km2 of forest land. This has effectively doubled the total drainage network in the GFE lands surrounding the park. The implications on ground water and stream flow are unknown.

Within these two watersheds there are 21 small, natural lakes (> 0.2 ha), three larger natural lakes (10, 22 and 31 ha) and two small (0.25 and 0.75 ha) reservoirs. The predominant lotic environment is the small forest stream (1st and 2nd order) comprising 80% (290 km) of the total length of the two major Park river systems (Table 6.1). The mature state of the forest within the Park provides canopy closure over most small forest streams, maintaining a stable temperature environment. In contrast, the larger 3rd and 4th order rivers of the Point Wolfe and Upper Salmon systems have wide shallow channels and limited numbers of large diameter trees in the riparian zone. As a consequence this gives them limited canopy closure. This difference in canopy closure provides the greatest habitat variation within the streams of the Park. First and 2nd order forest streams are cooler in summer and have less diurnal temperature variation than the 3rd and 4th order streams which are more exposed to sunlight (Figures 6.1 and 6.2). These shifts in thermal characteristics can be caused by recent forest harvest practices or by past log driving and its effects on the riparian structure. Thermal stress can lead to complete shifts in community structure such as the 1997 natural fish kill in Tracey Lake which resulted from an unusually dry, hot summer.

Table 6.1. Aquatic habitat by area or length for Fundy NP and adjacent lands within
the 'park watersheds' (areas of some of the lakes are from Kerekes et al., 1975).
Ponds for which no names exist on the 1:50,000 topographic maps
are typed in italics.

Figure 6.1. The weekly (approximately) maximum and minimum temperatures
(July to October 1992) in Point Wolfe River, Fundy NP. Sampling site
immediately upstream of confluence with Foster Brook.

Figure 6.2. The weekly (approximately) maximum and minimum temperatures
(July to October 1992) in Foster Brook, Fundy NP. Sampling site
immediately upstream of confluence with the Point Wolfe River.

In addition to the aquatic systems described above, there exists a gradation of wetlands ranging from standing water to areas of poor drainage. Because of the difficulty in defining where ‘wetland’ begins and ‘dry’ land ends, it becomes equally difficult to identify aquatic organisms. Many species can exist in either state and many require both habitats during various life stages.

When compared with terrestrial systems, less effort has been expended on identifying aquatic biodiversity and cataloguing its loss (Lydeard and Mayden, 1995). This ignorance of the aquatic ecosystem is evident within national parks as well as in the adjacent jurisdictions. Thus, many of the basic aquatic inventories have yet to be completed within Fundy NP and have been identified as high priority research topics in the 1997 Ecosystem Conservation Plan (Parks Canada, 1997).

It is not difficult to understand how this lack of action can happen. Most life in aquatic systems, in fact most of the aquatic ecosystem itself, is out of sight and therefore ‘out-of-mind’. Aquatic habitat degradation is not always obvious. We are not inhabitants of the aquatic ecosystem, and little direct economic ‘value’ comes from the aquatic system compared to the terrestrial. In addition, the necessary research may require more resources than comparable studies in the terrestrial system, as we lag in our understanding, and do not have the tools to conduct landscape-scale remote sensing of small aquatic ecosystems.

ABIOTIC FACTORS

The Nature Conservancy has adopted a four-level hierarchical classification scheme for aquatic communities (Lammert et al., 1997). These classes are Ecoregional Province, Ecoregional Section, Macrohabitat Type, and Habitat Unit Type. The first two classes place the aquatic ecosystem in the large landscape context, the latter two in the small scale physical context. Two of the aspects that are suggested to place an environment into the small scale context are water quality and quantity. Because of long term monitoring programs in the Park, we have information on these values. Many of the other aspects of classification for the GFE will need to wait for further local study and refinement of The Nature Conservancy’s classification scheme implementation.

Water Quantity

The discharge of small streams and large rivers responds rapidly to local precipitation (Coles et al., this volume) (Figure 6.3), and increases on degraded landscapes. Activities such as poor road building, break-up of soil integrity by heavy equipment, extensive harvesting (especially in riparian zones), and drainage of wetlands increase the range of discharge into a watershed. Most road systems comprise an extension to the existing river drainage network increasing peak flow and sediment transport.

Figure 6.3. Daily discharge for 1970 of Point Wolfe River, immediately
above the head of tide. Data taken from Environment Canada's
gauging station.

The Point Wolfe and the Upper Salmon rivers are in adjacent watersheds and show similar discharge patterns (Figure 6.4). The Upper Salmon River produces 28.6% more water annually than the Point Wolfe River from a land base that is 26.5% larger. A seven day running mean discharge of the Point Wolfe River provides a smoother curve that indicates the seasonal nature of these rivers. High water flows are cyclic, occurring between the period mid-March to mid-June and between October to December (Coles et al., this volume)(Figure 6.5).

Figure 6.4. Mean daily discharge (1970 to 1978, period of common operation)
of Point Wolfe River and the Upper Salmon River, each taken immediately
above head of tide. The upper solid line represents the flow of the Upper
Salmon River, the lower dashed line represents the flow of the Point Wolfe
River. Data taken from Environment Canada's gauging stations.

Figure 6.5. Mean daily discharge (1965 to 1995) of Point Wolfe River. The
data are smoothed on a seven day running mean.

Water Quality

The quality of water is a combination of both its chemical and physical properties, many of which are also related to its quantity. Acidity and silt are two high profile water quality measures that the public see affecting our aquatic systems. Acidity is a landscape scale pollutant that we, in the GFE, can have little direct control over; however, silt/sediment transport is generally a local issue and can be reduced by good management practices such as those recommended by the GFE guidelines (Woodley and Forbes, 1997; see Chapter 7).

Seasonality in the chemical makeup of the aquatic systems is a dominant feature associated with the high flows of the spring thaw. Woodley (1993) found an increase in the transport of Ca++ ions during a period of forest harvesting adjacent to the Point Wolfe River. Monthly water quality monitoring is conducted by Environment Canada at one site on the Point Wolfe River, and Park staff have conducted limited seasonal water quality surveys throughout the two river systems.

BIOTIC FACTORS

Biological communities are distinct assemblages of species that occur under similar habitat conditions and ecological processes. The classification of aquatic communities lags behind that of the terrestrial systems (Lammert et al., 1997).

Aquatic Vertebrates

Brook Trout and American Eel appear to be the only fish remaining in the Point Wolfe River and Upper Salmon River from pre-European settlement. Atlantic Salmon has either been reintroduced (Point Wolfe River) or has immigrated (Upper Salmon River) to the system after extirpation. American Shad, Gaspereau (Alewife), and American Smelt have been extirpated. Other less known minnow species such as Northern Redbelly Dace, Slimy Sculpin, Black Nose Dace and Chub are found in neighbouring watersheds, but not in those of the Park. Thus at least 66%, and possibly 80%, of fish species have been extirpated from the Park and surrounding lands.

The highest profile aquatic species in the GFE is the Atlantic Salmon. Inner Bay of Fundy Salmon are thought to exhibit a different life history from most other stocks of the northwest Atlantic. The adults are believed to have a more localized migration within the Gulf of Maine than other Atlantic stocks, which move to feeding grounds off Greenland. Due to the local nature of their migration, there is a higher percentage of returning grilse (one year at sea) compared to other stocks. The shallow nature of the rivers precludes the black Salmon (spawned fish) from overwintering in fresh or brackish water as is done in some larger rivers such as the Miramichi and Saint John Rivers. Adults returning to spawn in late autumn (October/ November) have been monitored by swim-through counts and, in recent years, by shore-walk counts. These counts, though imprecise, indicate a definite decline of stocks in both the Point Wolfe and Upper Salmon rivers (Figure 6.6). This may be related to the construction of the Moncton causeway in 1967 and 1968 which resulted in the subsequent decline of the Petitcodiac stock of the Atlantic Salmon.

Figure 6.6. The numbers of returning adults (multisea winter and grilse) observed
during the autumn spawning run in the Point Wolfe River and the Upper
Salmon River. The 1996 values were zero.

Juvenile Atlantic Salmon remain for two or three years in freshwater, until they smoltify and move out to sea in the spring of the year. The juvenile populations are monitored in the Park rivers by late summer electrofishing surveys. These surveys indicated that the individual growth and relative year class strengths were within expected ranges (Figure 6.7). In the Point Wolfe River, where most surveying has occurred, the distribution was not uniform throughout the river. Densities were low near the mouth of the Point Wolfe River (4.75 fish / 100 m2) and higher upstream (8.75 / 100 m2 at Foster Brook and 21.5 / 100 m2 at Bennett Brook).

Figure 6.7. The numbers of juveniles (ages 0+, 1+ and 2+) caught in late summer
electrofishing surveys of the Point Wolfe River.

The fisheries for the inner Bay of Fundy stocks, which includes those rivers found in the GFE, have been closed to all anglers for several years and show no promising signs of recovery (Anonymous, 1997). Within Fundy NP, three research studies are investigating possible stressors that may influence survival. These include: a comparison of the genetics of the remaining juveniles with the original stocked fish to determine whether our fish are returning to the same river, a study of over-winter habitat availability for juveniles, and a project on the hydrology of the Point Wolfe River to determine the depth of scour and deposition of the bed sediments (Coles et al., this volume).

The most common salmonid throughout the GFE is the Brook Trout. This fish should be considered a forest dwelling species, as it is limited by the high summer temperatures found in streams with low percentage canopy cover. Forest shade is a prerequisite for Brook Trout habitat in southern Canada. The small (1st and 2nd order) streams that provide much of this habitat contain relatively high populations of small trout. In a 1 km stretch of headwater stream within the park, the population was about 2,000 fish >8 cm length (Clay and Butland, this volume). The density was lowest in the upper 250 m, where the stream was often intermittent, and increased in the lower reaches as the flow increased and became more stable. The mean size of trout was 8.5 ± 2.4 cm (n=1445) in such forest streams.

Amphibians are the other major group of vertebrates commonly associated with aquatic systems. They have not suffered as critically from human interaction as the fish, probably due to their mobility and their reduced dependence on the aquatic environment. Many species or communities can be used as indicators, including both terrestrial and aquatic amphibians. Amphibians have several key traits often looked for in an indicator species: long life, high survivorship, low fecundity, often high abundance in forest ecosystems, vulnerability to both air and water pollutants, and many species are threatened or endangered. Within Fundy NP, we have monitored aquatic amphibians (Clay and Brownlie, 1997) and have, in recent years, modified our techniques in an attempt to be more sensitive in assessing change. Studies of amphibians in aquatic habitats (Waldick, 1994; this volume), terrestrial habitats (Adams et al., this volume), and ongoing trials on the use of automated call recorders for calling amphibians (Oseen and Wassersug, this volume) will lead eventually to an integrated amphibian monitoring program within the GFE that may identify long-term risk of loss of forest and wetland integrity.

Many species of birds and mammals are not normally considered ‘aquatic’, but depend upon or in some way utilise resources of the aquatic system, e.g. Common Loons, Grebes (Podicipedidae), Mergansers (Mergus sp.), Cormorants, Ducks and Geese (Anatidae), Belted Kingfishers, Waders (Scolopacidae), Herons, Otter, Beaver, Muskrat, Mink, Moose, and Shrew (Sorex sp.).

Aquatic Invertebrates

Aquatic invertebrates comprise the major biotic component of the aquatic systems of the Park and surrounding lands. Despite the importance of the invertebrate community, little work, aside from O’Brien (1995), has been completed on this group, although a preliminary inventory is nearly completed.. Leeches, worms, snails, and clams, in addition to insects, contribute to the macroinvertebrate community.

The most common use of aquatic macroinvertebrates in monitoring is as indicators for surveillance studies (Rosenberg and Resh, 1992). Benthic macroinvertebrates are the most widely used invertebrates for monitoring, as they offer the following traits: they are ubiquitous, they comprise a large number of species from which to select a wide spectrum of response, their relatively sedentary nature allows spatial analysis of disturbance, and they have relatively long life cycles compared to other invertebrates, allowing temporal studies of disturbance. Loss of habitat from log driving in the 1800’s is indicated by the long-lived Eastern River Pearl Mussel. No mussels were found in a recent survey below “Top Dam”, the driving dam furthest upstream on the Point Wolfe River. However, above the dam a population of “older” individuals was present. No reproduction appears to have occurred during the log driving era. In the GFE, much work remains to be done to permit an assessment of the usefulness of these organisms for monitoring.

Aquatic Plants

Two surveys of aquatic plants of lakes and rivers were conducted in 1994 and 1996 following the protocols laid out in Clay and Richard (1993 and 1995). Thirty-six species of aquatic plants were found in riverine environments and a total of 66 species have been identified for the Park (Clay and Richard, 1995 and 1996). Work to date has only involved inventory and no community analysis or comparison with sites outside the Park has been attempted.

LOSS OF INTEGRITY

Management at the landscape scale requires identification and understanding of the linkages between habitat and populations. To understand the functions that control these linkages in an undisturbed ecosystem and how these functions may be affected by land use practices, local scientific information is required to develop and guide local management planning. Hirvonen and Madill (1978) and Woodley (1985) documented the natural history of the park after three decades of protection. To complete our understanding of the GFE, we require a vision of what Fundy NP was like before the 'industrial forest'.

To visually recreate the ecosystems of 100 years ago, Cooper and Clay (1997; this volume) documented the history of logging within Fundy NP and the adjacent high plateau lands along the north shore of the Bay of Fundy. The objective of this review was to develop an understanding of how the logging industry may have influenced and degraded the riverine systems. Much of the human history that has shaped Fundy NP is recent enough that many participants are still alive. Local residents were able to provide much of the information missing from written records and, in addition, they were able to clarify incomplete written documents.

This review was essential to determine the baseline status that will help identify our target values for the maintenance of aquatic ecosystem integrity. Although there are ecosystem stresses within the park, it is the external threats to ecosystem health that pose some of the greatest challenges. Each individual action taken alone poses only a minor threat and with appropriate mitigation can often be accepted when viewed in isolation. However, when viewed on an ecosystem scale, each individual action is additive, and the cumulative ecosystem change may not be acceptable. It is necessary to assess these cumulative changes on the basis of an historic baseline and not view each on the basis of the current situation. Otherwise we risk incremental deterioration of environmental quality as has happened in our rivers. In order to provide practical advice it is necessary to understand the composition, structure, and function of ecosystems. The lack of understanding of our original local ecosystem limits the management advice we can provide for the aquatic systems of the park and the GFE.

One of the primary aims of national parks policy is the promotion of greater understanding and appreciation of our environment. A secondary objective is to restore degraded park ecosystems, where possible. It is unlikely that we will ever know for certain what the rivers of the Fundy coast were like, or would have been like, had river driving not occurred. Our best estimate of the historic ecosystem structure can only be made after details of the major anthropogenic influences are documented.

Many organisations and agencies in Canada, including Parks Canada, are striving to maintain ecological integrity. In the case of our aquatic ecosystems this has been inadequate and some restoration is warranted.

EXOTICS AND INTRODUCTIONS

Introduction or transfer of exotic species is important in both terrestrial and aquatic ecosystems. There is a world-wide problem of large scale unintentional introductions in aquatic environments due to actions such as dumping ship’s ballast (e.g. Zebra Mussels). Exotics are not a major problem in the Fundy freshwater aquatic systems. However, potential risk does exist with the introduction of new genetic strains and possible disease through stocking and restoration programs. In addition, recreational use of our national parks increases the potential introductions of feral carnivores, seeds and escapements of fish, reptiles, plants and other species.

INDICATORS

Indicators are used to monitor complex functions through the use of a simpler measure. In some cases indicators can be single species that represent a guild or some community group. In other cases it can be a species or community that is being used to integrate the effects of pulse type anthropogenic effects over time. In many aquatic systems understanding is incomplete and it can be difficult to identify a specific indicator. Often the threat is unknown, thus making an indicator impossible to identify. An additional complication is the loss of integrity that the ecosystem may have undergone.

In terrestrial systems, viable population size of the most ‘sensitive’ species is often used as a means of estimating the minimum critical habitat necessary to maintain an ecosystem. In aquatic systems, the physical size of the system or watershed may determine which species are present. Indicator species should be chosen because they exhibit one or more of the following characteristics: keystone, dominant, vulnerable, and integrators. Charismatic megafauna are often selected without reference to these criteria as a research preference. For many lakes, the Common Loon could provide an indicator of wilderness quality. They require a significant quantity of high quality food and a low level of human activity. For many river systems (3rd order and larger), Atlantic Salmon can provide a similar indicator. Unfortunately, many systems have already been degraded to the point where these species are no longer well established.

The most widespread fish in the smaller streams of the GFE is the Brook Trout. This species is a sensitive indicator of habitat effects that result in elevated temperatures and suspended sediments. In many aquatic systems, we will initially require a simplistic suite of indicators. In time, with further work, a more refined system can be established utilising appropriate macro-invertebrates in addition to those vertebrates mentioned above.

SYNOPSIS

From our present paradigm, the aquatic systems within Fundy NP appear near pristine. They have, however, been severely affected by historic forest practices and to a lesser extent by present forest harvest activities.

Some impact is unavoidable and with appropriate mitigative measures, including watershed-scale management, can be tolerated. It is vital that the cumulative impacts of any development within a watershed be documented. There have been many statements about the significance of the aquatic ecosystem by governments, industry, and even the Fundy Model Forest. Despite this acknowledgement, the aquatic ecosystem often gets little attention beyond broad statements. It is important to recognise the significance of the aquatic ecosystem and its relationship to our terrestrial system and to ensure that we fully comprehend and appreciate the effects of our impacts.

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Information provided by:
Dr. Graham Forbes
Faculty of Forestry and Environmental Management at UNB
Last Update: May 7, 1998
This document: http://www.unb.ca/web/forestry/centers/cwru/soe/chapter6.htm