Regier, H.A., Kay, J.J., 1996 "An Heuristic Model of Transformations of the Aquatic Ecosystems of the Great Lakes-St. Lawrence River Basin", Journal of Aquatic Ecosystem Health, Vol. 5: pp.3-21
Many aspects of the degradation and partial recovery of Great Lakes Basin ecosystems are well-known. By the 1960s, major parts, especially in the southerly third of the Basin, were so severely degraded that political decisions were taken to do something about it. Following some quarter century of corrective activities, with a total cost of many billions of dollars, reductions in levels of several kinds of abuse, and partial transformation to ecosystem states with more desirable features, are apparent. Reports on the degradation and recovery processes - both with respect to cultural and natural features of the Basin - are still quite fragmented. It is our hope that the descriptive, heuristic model proposed here, with further development, will provide a useful framework for understanding many of the structures and processes of the degradation and recovery phenomena.
An ecosystem may be perceived to be self-organizing, holarchic and open, in a way consistent with what Koestler (1978) termed a SOHO system. A SOHO ecosystem may exist in many different variations of one type or it may perhaps appear, through major transformation, in more than one type or manifestation. A classic two-dimensional diagram by Vollenweider (1968) relates a set of types of manifestation of aquatic ecosystems - whether oligotrophic, mesotrophic, or eutrophic - to two functions of external factors. This diagram may be perceived as a phase diagram, a projection in two dimensions of a three dimensional catastrophe model. Two attractors that could generate such a catastrophe model and phase diagram might be a benthic attractor and a pelagic attractor, with the benthic attractor usually the more powerful of the two in pristine nature, according to Margalef (1968). Cultural interventions have often impaired the benthic and fostered the pelagic attractor, sometimes causing a transformation. This complex notion is explored here as a descriptive, heuristic model for rivers and lakes in the Great Lakes-St. Lawrence River Basin and various well-known partial generalizations of relevant phenomena are summarized briefly and related to it.
Our paper is an attempt to develop a more general integrative model, of the ecological features of the degradation and recovery sequence of these ecosystems, than is yet available. It may prove useful in attempts to relate regional, systemic phenomena to biosphere transformations related to climate warming and ozone depletion. At the present stage of its development it is a descriptive, heuristic notion for general visioning, learning, and planning purposes (Westley, 1995) rather than an operational tool for making practical plans and decisions. However this model is firmly rooted in the emerging notions of complex systems theory and post-normal science. (Kay and Schneider 1994, Schneider and Kay, 1994b)
We start with a series of published generalizations that we take to be interrelated with, and relevant to, our more comprehensive, if not more comprehensible, notion. We then present our descriptive model and relate it to these generalizations.
Though the Great Lakes are sometimes called "inland seas", in their pristine states they were not much like marine seas ecologically. In some ways, they did resemble the pristine north-easterly half of the Baltic Sea quite closely (Harris et al., 1988; Regier et al., 1988). It happens that the geological and evolutionary histories of the Great Lakes and the North-East Baltic regions are very similar. With major transformations due to human interventions, the Great Lakes came to resemble some coastal shelf seas of similar latitudes more closely, as sketched below.
The aquatic part of the Great Lakes-St. Lawrence River Basin may be termed "The Great Laurentian River", with the lakes taken as natural reservoirs or giant eddies in the River. The River Continuum Concept of Vannote et al. (1980) and Minshall et al. (1985) has been expanded into a land-stream-bay-lake-river continuum by Regier et al. (1989) and Sedell et al. (1991). Though lakes and rivers are often treated as qualitatively different types of waters (e.g. Randall et al., 1995), these types may perhaps be reduced to a single continuum for some purposes by using the concept of "water residence time" as a continuous variable to encompass both types. Further, one of the Great Lakes is like a large one-sided river, flowing predominantly in a counter-clockwise direction as a giant complex eddy.
Incidentally, as a coincidence of geography, hydrology and political history, this generalized flow regime causes much of the pollution generated on the U.S. side of these waters to hug the American shore downstream from its sources, and vice versa. This is also the case with downstream effects - good and bad - of shore alterations of various kinds, as reflected, say, in sediment transport. Regional ecological features, that relate closely to large-scale atmospheric phenomena, such as vertical stratification of deeper waters seasonally and to the seasonal migration of fish and birds, are influenced strongly, but not constrained fully, by such a generalized flow regime.
In freshwaters, the nearshore littoral biotic association generally exhibits more species than the offshore open-water, lentic. In pristine freshwaters, lakes and rivers as in the Great Lakes Basin historically, insects that dwell on or in the bottom and on macrophytes are an important trophic link between plants and fish, as compared to zooplankton that provides a major link between phytoplankton and fish in deep old lakes and in open marine systems.
The generalizations above are summarized from review papers by Fernando and Holcik (1991) and Fernando (1994), with sources that include Hickling (1961), Frey (1990), and Wetzel (1990).
The benthic association as such may be perceived to exploit, or harvest, the production of accessible parts of the pelagic association, with a reverse flow of trophic products,which is usually comparatively small except at times of moderate disturbance of the benthic associations. The harvesting by the benthic association may be both active and passive. The latter because the living things of freshwaters have a density greater than water and thus tend to settle out, especially following death. The benthic association usually gains asymmetrically in terms of mass, energy, and embodied information with a net transport from the pelagic to the benthic with respect to each of the three kinds of "resources".
(The "information" resource, as discussed below, consists in part of particular kinds of organic molecules, e.g. lipids, proteins and vitamins, that are assimilated by the benthic organisms from their pelagic food; in other words, the food selected contains not only mass and energy of appropriate types, but also information of appropriate types. For example, phosphorus is an information resource in that it contributes to adenosine triphosphate, or ATP, which possesses the technique of transporting energy efficiently, i.e. with minimal loss of exergy, within an organism. Here information is understood to be as "real" as are mass and energy.)
Because of the greater organizational "power", in a thermodynamic sense (Schneider and Kay, 1994a, 1994b), of the benthic over the pelagic, except in places and times of violent perturbations, oligotrophy is the usual state of freshwater ecosystems. A eutrophic state exists naturally where the benthic association is comparatively weak for some reason, or nutrients enter the lake at loading levels high enough to swamp the assimilative capacity of a normal benthic association. This dominance of the benthic over the pelagic can be argued to follow from the constraints of the second law of thermodynamics (see e.g. Schneider and Kay, 1994a).
Natural aging of a water body through infilling with sediment,or with partly decomposed organic matter, need not lead to its "eutrophication", and eutrophication need not resemble natural aging of the waters. The confusion on this issue, especially in interpretive scientific writing, has been widespread; e.g., rhetorically, if cultural eutrophication resembles the inevitable natural aging of a lake, what's so bad about cultural eutrophication? A resemblance, in cases where there appears to be a resemblance, is superficial.
The above summary is based partly on work by Margalef (1968, 1990).
The emergence of a self-organizing pelagic association in an aquatic system under appropriate conditions has no counterpart on land. The atmosphere can support only slight manifestations of a self-organizing atmospheric association compared to that of the hydrosphere. Enrichment with plant nutrients does not lead to eutrophication of the atmosphere, perhaps because various preconditions for photosynthesis cannot be met. In effect, the properties of water - including its density, solubility, and transparency - permit development of a kind of self-organizing ecosystem phenomenon, the pelagic association, that has no organized counterpart on land.
In an oligotrophic aquatic ecosystem, with only a fragmentary and seasonally intermittent pelagic association, that follows a dimictic pattern with the vertical mixing of the water that is associated with the equinoctial storms of spring and fall, the benthic biotic association is organized generally in a way similar to the association of terrestrial ecosystems. Fish and diving ducks of the types that forage in open waters are aquatic counterparts of birds that forage "in the open air" over land. At the land-water ecotone semi-aquatic birds, mammals, amphibians and reptiles can function opportunistically both on land and in the water.
This general sketch is based in part on Regier and Henderson (1973), Francis et al. (1985), Sedell et al. (1991) and others.
The biotic association of the sub-dominant domain may organize defensively by minimizing its "surface area" say by forming into circular or spherical patches, and by behavioral movements to limit its direct contact with the "surface area", whether continuous or episodic, of the dominant system.
In relatively oligotrophic, pristine, aquatic ecosystems, whether lakes or rivers, external "feeding" of the water body may occur predominantly in seasons when the benthic association is suppressed because of destructive storms, low temperatures, water fluctuations, etc. If the feeding involves soluble phosphates and nitrates, then the pelagic has a temporary advantage over the benthic, but this advantage may be lost when the aquatic system settles down again. A pelagic association tends to be relatively more successful following spates and vertical turnover, which both involve transport of nutrients, associated with the disruptive equinoctial storms of spring and fall, than in summer and winter. Thus the two-dimensional size of the effective boundary layer between the benthic and pelagic association may expand and contract, with two cycles a year in the Great Laurentian River Basin.
With respect to the boundary between land and water, whether at or below the surface of the water, the more complex the firm physical boundary the more complex the benthic association is likely to be; at least where the hydrological regime is not violently turbulent (Regier and Henderson, 1973). Such complexity will contribute to the dominance of the benthic over an adjoining pelagic system. The complexity of the pelagic system may depend in part on any relatively stereotyped, hydrological complexity of the water body as such. Up to a level of moderate hydrological complexity, the pelagic biotic complexity may reflect that of the hydrological complexity (Brandt et al., 1980).
The magnitude and seasonal timing of nutrient loading into shallow waters appears to influence whether macrophytes play a major role. The Aufwuchs, the biotic association directly on the surface of the macrophytes, may then exploit the plankton thus clarifying the water and the macrophytes may structurally prevent the currents and waves from stirring up the bottom to cloud the water (Harris, 1994).
In an eutrophic/pelagic association a quasi-linear trophic chain with several major links may serve as an appropriate heuristic model. In an oligotrophic/benthic association a dimensionally more complex network with a number of nodes and non-linearities is a usual model. In waters of transitional or mesotrophic state, chain-like trophodynamics may appear in spring and fall, and web-like trophodynamics may appear in winter and especially in summer. Presumably, within equal time intervals, the higher temperature of summer would permit a more complex system to evolve than would the lower temperature of winter. Associations between species that thrive in spring and fall pelagic conditions, and in eutrophic conditions, may thus be described trophodynamically with linear models. Associations between species, which thrive in summer benthic and oligotrophic conditions, require more complex models. Some flexible taxa such as yellow perch and walleye can succeed, through adaptive modifications of life history and behavioural features, both in relatively linear and relatively complex trophic systems of seasonally fluctuating mesotrophic conditions, but do not thrive in abundance in strongly eutrophic linear systems or in strongly oligotrophic complex systems.
It should be emphasized that the types of lakes addressed in this section are all deeper than several meters, - the type discussed in section 6 above. There appears to have been no relatively comprehensive comparative study of the generalized type of shallow lakes that grade into wetlands.
Individual (deeper) lakes that have undergone eutrophication and subsequent partial oligotrophication, due to changes in phosphate loading, have been tracked through time as a vertical line at the particular relevant value of the mean depth/residence time constraint ratio in a standard Vollenweider schema. It has been noted that transitions from an oligotrophic state to a mesotrophic and then to an eutrophic state occur at levels of external phosphorus loading with higher numerical values than the transitions in the opposite direction following remediative interventions to reduce phosphate loading. This appears to imply some hysteresis, i.e. some resistant organizational mechanisms which cause a lag in response in one direction different from that in another direction.
Figure 1: A tentative catastrophe model for aquatic ecosystems: One attractor, associated with high loading of phosphates into relatively shallow waters with high residence time, relates to an eutrophic state. The other attractor associated with low loadings into deep waters of low residence time, is associated with an oligotrophic state. The narrow zone of mesotrophic conditions may be related to the unstable overlapping part of the catastrophe fold. The horizontal projection of the surface (control space) is the so called "Vollenweider chart". The vertical projection gives a fold catastrophe surface similar to that presented in Scheffer et al. (1993). The axis labeled P, the phosphorous loading in the lake (or other nutrient loading), corresponds to the Y axis is the Vollenweider chart and Scheffer fold catastrophe diagram. Depth is the mean depth of the lake as in the X axis in the Vollenweider chart. Turbidity is the z-axis and corresponds to the x-axis in the Scheffer fold catastrophe diagram. (Other indicators of water clarity could be used).
General observations such as these can perhaps be summarized in the form of a three dimensional Riemann-Hugoniot catastrophe model (See Figure 1) (Huseyin 1978; Kay, 1984, 1991, Jørgensen, 1992). (Kay 1991, appendix and Jørgensen, 1992 chapter nine are introductions to catastrophe theory in ecology.) One attractor, associated with high loading of phosphates into relatively shallow waters with high residence time, relates to an eutrophic state. The other attractor associated with low loadings into deep waters of low residence time, is associated with an oligotrophic state. The narrow zone of mesotrophic conditions may be related to the unstable overlapping part of the catastrophe fold, consistent with observations of marked instability in this zone. The horizontal projection of the surface (control space) is the so called "Vollenweider chart". The vertical projection gives a fold catastrophe surface similar to that presented in Scheffer et al. (1993).
Under an appropriate set of climatic, physiographic, hydrological, and bioregional conditions, a water body may remain permanently stratified in a vertical dimension, - a condition termed meromixis. Localized exceptions may involve upwelling of water from the deeper layer into the shallower layer. Such stratification, with episodic local surface or subsurface upwellings at the boundary of a water mass, is the usual case in the open ocean and in a few lakes, e.g. Lake Tanganyika.
Human influences may cause a lake to change from a dimictic regime, in which top to bottom mixing occurs twice a year at spring and fall overturn, to a meromictic regime where complete turnover does not occur; though some mixing may occur seasonally at the boundary between the layers. A phase diagram and a complementary catastrophe model could perhaps be sketched for such a dimictic to meromictic transformation and its reverse. The benthic and pelagic associations would play roles, with the meromictic association in some ways, perhaps, being a more extreme version of that in the seasonally-isolated, hypolimnatic waters in a dimictic case. There is evidence that this type of transformation to meromixis might occur in some waters with a particular kind of climate change regime (McCormick, 1990).
Further, a water body that is loaded, either naturally or more likely culturally, with putrescible organic matter may be described with a phase diagram and a catastrophe model of some type. More attention has been focused on this general phenomenon as it relates to streams, e.g. in the Saprobian System approach (Cairns et al., 1972), than in lakes.
It may be feasible to sketch a combined, multi-dimensional phase diagram and catastrophe model for interactions between the benthic and pelagic associations for the three examples above, and for other types (Steedman & Regier, 1987 and Jørgensen,1992) and for each of the various segments of the land-stream-bay-lake-river continuum sketched earlier, or for some integrated continuum state variable.
In waters like the Great Laurentian River, the normal succession leads not only to the relative dominance of the benthic association over the pelagic but also, within the benthic association, a shift from an earlier abundance of r opportunists to larger organisms with some K properties. (Here r and K are as defined by Ricklefs (1973).) In what is sometimes termed a "late successional stage" in pristine waters, the benthic association contains numerous large organisms of long-lived species. It bears resemblance to the "old growth forest" characterization of terrestrial ecosystems but there is no botanical counterpart of large trees in these waters except, perhaps, in kelp beds in some coastal seas and in the zoological coral skeletal material of tropical reefs. Perhaps an "old growth plains" association with short deciduous and herbaceous vegetation and large migratory mammals and birds may be a better analogue of "old growth waters" as in the Great Laurentian River Basin.
The usual maturation sequence with self-organizing, holarchic, open systems has been described (e.g. by Bertalanffy, see Davidson, 1983) as involving four progressive interactive processes; here interpreted with respect to aquatic ecosystems (Regier & Henderson, 1973; Francis et al., 1985):
The information system balances a tendency toward internal efficiency within the ecosystem and external effectiveness in interacting - competitively and/or mutualistically - with adjoining ecosystems. In situations where external conditions are generally benign for an extended period of time an ecosystem may "mature" to a state that renders it quite brittle to an unusual external disturbance. Internally it may be thermodynamically effective, but externally its potential flexibility and effectiveness may be constrained strongly. The emergent tendency toward maturity has been termed "ascendency" by (Ulanowicz 1986, 1989; Ulanowicz & Tuttle 1992) and extends the earlier summary inferences of Bertalanffy and others (see Davidson, 1983).
Naturally-occurring, disintegrative events followed by successional re-integration have been sketched heuristically by Holling (1986) as a convoluted cycle,that is a figure 8 lying on its side. The ascending sigmoid arm of this cycle corresponds to "Bertalanffyian maturation" as sketched above. The reverse inverted sigmoid arm corresponds to the natural disintegration sequence following a major natural disturbance. How this "rejuvenation", or re-set process, is organized has not attracted nearly as much attention, from ecologists and systems scientists, as has the maturation sequence. Presumably, the "system disassembly process" of the reverse arrows of Holling's figure 8 are organized sequentially to a degree comparable to that of the "assembly process" (usually termed "maturation") in ecosystems, where a particular figure 8 sequence is a "normal" repeated phenomenon. In such cases, the whole figure 8 phenomenon may evolve to meet a criterion of a balance of internal efficiency and external effectiveness, see above.
A mistaken notion, that ecosystemic transformation and disintegration due to interventions by technologically-careless humans closely resembles that associated with natural disturbances, is common. The potential for rapid recovery to a desirable ecosystem state is usually strong with natural disturbances but may not be so following disintegration to a degraded state due to various kinds of human interventions. The "reverse arrows" part of the figure 8, in natural situations, may involve processes to conserve types of mass, energy and information that are locally in short supply, and this does not generally happen with careless human interventions.
A cultural stress may resemble a "beneficial" natural process and then be perceived as a "eustress", or it may be "harmful" and thus a "distress". The emphasis here is on "distresses".
When starting with a pristine, aquatic ecosystem, especially if it happens to be in an old growth phase of a cyclic manifestation, most kinds of cultural interventions in the past were followed by consequences that bear some resemblance to those that follow partial ecosystemic disintegration of a pristine ecosystem due to unusual natural disturbances. Thus the role of pristine centres of organization, with the related associations of K species, is impaired. Decentralization of effective organization occurs, the habitat niches of species pre-adapted by chance to the particular stress broaden, the relative abundance of sensitive K species decline, with an increase in abundance of tolerant r species, interactions between species become less stereotypical and mutualistic, and more opportunistic and predatory, and the complex trophic network simplifies into one or several, relatively independent, linear chains.
By analogy with a general inference by Selye (1974), with respect to the physiology of mammals, Rapport et al. (1985) termed the above generalization on ecosystem disintegration a "general adaptive syndrome".
It is important to emphasize that the above generalization may not apply to all kinds of human interventions, but rather to most kinds that have occurred in the past in the aquatic parts of the Great Laurentian River Basin. Massive acidification with H2SOx and HNOx may result in a quite different kind of transformation, with an acid-tolerant, "pathologic", benthic association replacing the pristine benthic or pelagic association. Also the generalization includes only part of the ecosystemic effects from any relevant stress, other parts of such effects may be unique to a particular stress. The unique consequences must be used in any attempt to diagnose the cause of an ecosystem disintegration. This obvious guideline has often been ignored in attempts to find causes for particular ecosystemic changes.
With respect to the heuristic notion of a water body containing both a benthic and a pelagic association, at least potentially, a general adaptive syndrome as sketched above may be reflected largely within the benthic association at early stages of human interventions in a water body. Initially, human activities in all the four major classes sketched above - removal of abiotic things, removal of biotic things, addition of abiotic things and addition of biotic things - were focused mostly in the nearshore benthic part of the aquatic ecosystem in the mouths of rivers and adjoining bays. As harmful interventions extend further in space, and intensify in any locale through time, the relative power or self-organizing capability of the benthic association becomes progressively more impaired. If the cultural interventions, separately or jointly, become sufficiently intense, the pelagic association may organize with an offshore, positive-feedback process which may then "empower" the pelagic to suppress what is left of the benthic association, which then becomes sub-dominant (Steedman & Regier, 1987; Regier et al., 1989).
In pristine conditions, natural disturbances may seldom have consequences sufficiently great to invert the relative dominance of the benthic over the pelagic parts of the association in water bodies that are naturally oligotrophic. But, this may occur occasionally in nature in circumstances which render the water body vulnerable to such a transformation; the Central Basin of Lake Erie with its hypolimnion of large area, but thin depth, may be a case in point (Reynoldson & Hamilton, 1993).
Positive feedback loops have been inferred with both the bottom-up and top-down kinds of mechanisms. For example, Ulanowicz & Tuttle (1992) used a complicated model of carbon flows in a mesohaline Chesapeake Bay ecosystem to demonstrate a positive feed-back role for oyster in complementing the effect of reduction of nutrient loadings in attempts to reverse the eutrophication processes in the Bay. Something similar may be occurring in the Great Lakes following introduction of the zebra and quagga mussels.
According to the inferences of W.D. Taylor (1995, University of Waterloo, personal communication), top-down predators in lakes help to maintain an oligotrophic, planktonic environment by preying on visual planktivores which permits more small plankton to die uneaten and to drop into deeper waters. Here it serves as food for a heterotrophic benthic association including insects (see section 2.2 above). In the pristine Great Lakes, the large top-down predatory fish preyed on the relatively scarce, small, planktivorous fish, on large planktivorous zooplankton or larger insects, and on smaller benthivorous fish.
Positive feedback processes may appear both in the eutrophication process, which leads to dominance by the pelagic system, and in the oligotrophication process which leads to dominance by the benthic system. Systemic negative-feedback processes may compensate for relatively small distresses and contribute to hysteresis in the transition between the two attractors.
Koestler's symbol of a holarchy as a tree may imply a greater rigidity than he had intended. A complementary concept of a "polyarchy", as in an electoral democracy with its actor groups and vertically nested governance institutions, both formal and informal, may be appropriate. The "polyarchy" concept as sketched by John Dryzek (see Murphy, 1994) may be distinguished from "poliarchy", or egalitarian, communitarian governance at a level of a small community or polis together with vertical anarchy with respect to any higher levels of organization. Such a concept is attributed to Murray Bookchin (see Murphy, 1994).
Koestler combined two perceptions about living entities in the General System Theory of Bertalanffy (1952) - holarchic organization and open system behaviour - "to get a Self-regulating Open [Holarchic] Order, or SOHO for short". This synthesis was intended, in part, to transcend the gridlocked conflict between:
A holon (etymologically a combination of elements meaning "whole" and "part") is an element of a holarchy and may often be a sub-holarchy within a larger holarchy. What is a holon, as opposed to a holarchy, or text and context, depends on the perspective and interests of the observer. "The term holon may be applied to any [relatively] stable sub-whole in an organismic, cognitive, [ecological] or social [holarchy] which displays rule-governed behaviour and/or Gestalt constancy" (Koestler, 1978). The holon's set of rules may be called its canon; it is apparently within the capabilities of a holon to participate in modifying pre-existing, or adding new rules to its canon, in an emergent evolutionary way.
The holon acts so as to persist as a semi-autonomous whole and it is the canon of information that persists more or less intact through continuing restorative processes to compensate for recurring losses. Mass cycles and energy cascades incessantly through the holon in the relevant domain of space and time. Its canon is composed of information of many kinds that is apparently holarchically harmonized, but not fully unified. In order to persist, the holon must adaptively "manage" semi-autonomous holons within itself (perhaps through something like a facilitated multi-stakeholder process as in a polyarchy) and must risk involvements of many types, with and within other holons. Hence its Janus-faced behaviour of balancing inward looking and outward looking. The holon uses matter, energy and pre-existing packaged information (e.g. "food", exocrines, the services of mutualistic symbionts) continuously as "resources". The canon of information is the primary focus of the science of holons and holarchies, as in ecoscience as a field of biology.
It is unlikely that a holon will exist in static state for any length of time, though something like this may be approached by some kinds of holon in a "resting state". If and when transient, quasi-steady state occurs, it may be as a result of a complex balance of internal and external influences, some of which are holarchic. A scientific characterization of the holon, while temporarily in steady state, would be like an instantaneous photograph of a living thing with a Gestalt that one would not expect to recur again in all its details. As with all scientific concepts, homeostasis and homeorhesis are abstractions, - but often practically useful abstractions if their limits are explicitly noted.
Something like a birth-maturation-senescence-death-disintegration-fertilization-germination-gestaion-rebirth... branched sequence occurs and recurs "normally" with many kinds of holons in different parts of holarchies (Holling, 1986; Kay, 1984). Different ecoscientific observers have tended to focus on different parts of such a cycle.
Ovoids refer to three multi-dimensional ecosystemic domains; left ovoid reflects the fully natural state; central slanting ovoid reflects different levels of ecosystemic degradation due to cultural abuse; right ovoid reflects a healthy natural/cultural ecosystem or landscape mosaic. The state of healthy self-integration is high at the top of the figure and low at the bottom. Earlier discussions of this schema may be found in Regier & Bronson (1992) and Regier (1993a).
Suppose that our initial focus of attention relates to the measure of system organization, MSO, which may be "ascendancy" as defined by Ulanowicz (1986), at points a year apart, - say in late summer. An ecosystemic cycle of the type sketched by Holling (1986) may take years, decades, or centuries to run its course. Superimposed on the stylized cycle will be year-to-year jiggles and wobbles, and occasional reversals or forward spurts, depending upon annual differences within the holon's environment, inter alia.
Secondly, focus iteratively on both the long-term trajectory and, for a particular year, the day-to-day deviations from it related to the seasonal sequence. Here a standard time of day, say 10 a.m., may be chosen for the daily MSO or integrative state variable. The seasonal trajectory includes seasonal phenomena and may in turn be perceived as a cycle, - linear back and forth, roughly circular, convoluted as a figure eight, etc. Such a cycle would link the two points that are a year apart on the large trajectory.
At a third level there may be a daily cycle of points an hour apart. Day and night differences may be quite pronounced, with a daily cycle of some form.
The combined trajectory would show a line which traces three cycles of different scales as nested one within the other. As sketched here the holarchy of MSO cycles might suggest some of the diagrams of fractals generated by B. Mandlebrot. The measure of system organization, MSO, to be used to characterize such a trajectory would presumably relate to the holon's canon, i.e. it would relate to "information" that is persisting more or less intact. If the canon were to change, the shape of the bounding ovoid, and of the various cycle trajectories, would also change. And we expect such changes that are usually gradual, but with some rapid episodic events.
The generalization above about the complicated trajectory appears to apply to a variety of different holons, e.g. the ecosystem as holon, the population of a species in a locale, and the individuals within the population. This all may be perceived as a rather laboured general characterization of what any ecological field worker already knows directly and takes into account routinely, if mostly implicitly. It may be time now to treat these phenological phenomena as important and not just as inconvenient noise.
Parts of the Great Laurentian River's aquatic system that were severely altered appeared to self-organize "pathologically" and became stabilized and trapped in new domains that humans found undesirable and often offensive. A degraded ecosystem's emergent canon apparently had adaptively incorporated new information that created positive feedback processes that accentuated and stabilized undesirable features. An analogy might be an algorithmic "virus" in a computer that disassembles the computer's existing program and re-assembles another kind of program that could still accommodate some of the inputs for the first program. Such an ecosystem, or other "adapted holon", may not be pathological when perceived from a biosphere or Gaian perspective in that it may be offering appropriate services, such as exergy dissipation (Kay, 1991), but somewhat differently, and less effectively, than in its earlier state. Certain stresses - e.g. phosphate loading that triggered eutrophication, phosphate combined with heavy metal loading that triggered methylation of heavy metal ions to the disadvantage of large organisms, overfishing of piscivores combined with exotic introductions of planktivores appear to have caused the ecosystem to self-organize into relatively simple, but robust, self-reinforcing "pathological" states (Steedman & Regier, 1987).
The oblique ovoid, with the bottom as the state that follows severe disintegration of natural ecosystem organization, is meant to symbolize the adaptive pathological state caused by careless and abusive human interventions in a Great Laurentian River ecosystem. Many of the Areas of Concern, in severely degraded parts around the edges of our waters, had transformed into such a pathological state (Hartig & Vallentyne, 1989).
Remediative reduction in the levels of the various stresses has not led to an immediate, commensurate, rehabilitative ecosystemic response, and some form of systemic hysteresis has been apparent. This in itself implies self-perpetuating capabilities of holons, even in such pathological states, and these have been studied to some extent (see below).
After strong and protracted remediative efforts of the appropriate type, it may be that the pathological ecosystemic traps may all be sprung and all parts of the Basin's aquatic ecosystems will enter, separately and jointly, a self-reinforcing rehabilitative process toward some more desirable "normal" state (see horizontal ovoid to the right of Figure 2). This appears to be underway now, in a kind of haphazard and very slow remediation process. Through the Lakewide Management Plan process, some attention is beginning to be directed to the ways in which the various sub-systems are breaking out of the self-organizing pathological domains. If desirable "normal" self-organizing ecosystemic states emerge in the currently degraded parts of the Great Lakes they will not likely come together to resemble closely the pristine state phenomenologically, except perhaps in the northerly parts of the Basin. The emergent "optimal points" to which ecosystems in the southerly waters will tend is not predictable, except perhaps with respect to some general systemic properties (see below).
Perhaps inevitably, the "normal rehabilitated state" of most Great Laurentian River ecosystems will reflect some features of the pristine state: some which have been purposefully designed by humans, and some that arose "accidentally and unpredictably" under the influence of the joint natural and cultural influences acting in, and upon, the particular ecosystems. Some unique indigenous species with their canons have been extinguished and exotic species have become "naturalized". The rehabilitative design of degraded systems is gradually coming to be addressed in the context of lake-wide Fish Community Objectives, Remedial Action Plans, and Lakewide Management Plans. These systems can be "managed" by humans to an extent implicit in that connotation of "management" which relates to the achievement of some desirable ecosystemic consequences as a result of "managed" cultural influences that will remain relatively small, regardless of their economic cost.
In summary of this section on macrodynamics of ecosystemic holons, with the help of R.E. Munn (University of Toronto, 1993, personal communication), we propose some light-hearted (or is it light-headed?) jargon to denote the various kinds of transformations in Figure 2.
In a cultural/natural ecosystem that exhibits "integrity" the FLIPs will likely be constrained to a smaller scale than was the case with the natural state. Humans are too insensitive to permit a high level of natural self-organization and will intervene to prevent most of the major disorganizational FLOPs. Major catastrophes - wars, floods, fires, earthquakes and hurricanes - are quite uncommon in the Basin of the Great Laurentian River.
It may be noted that the jargon sketched above is appropriate for a reductionistic analysis of the dynamics of aquatic ecosystems as holarchies. Obligate reductionists should be able to work happily and to continue the analyses to lower levels of the holarchy, with the above as a start. For example, physiological and genetic processes are involved in the mini-FLAPPING and FLAPPING.
Most parts of the Great Laurentian River ecosystem may be perceived to consist of two major holarchic subsystems or holons:
Margalef (1968) noted that, in generally benign locales, biotic parts of ecosystems that relate to relatively firm substrates tend to self-organize (e.g. as in a Bertalanffyian sequence, see above) to a more "mature state" than do biotic parts of an ecosystem that exist in fluid space. Others (Sedell et al., 1991) infer that the more intricate and firm the solid surface to which biota relate, the more complex the biotic system is likely to be. This is also the case with hydrological structure within pelagic spaces (Brandt et al., 1980), but the degree of constancy, intricacy and firmness of hydrologic "structures" within a pelagic zone is usually much lower than within a relatively benign riparian-littoral-benthic zone. An intense storm can severely disturb both the benthic and pelagic spatial structures, causing a temporary retrogression or re-set.
Margalef (1968) noted that the more highly organized biotic associations of a benthic holon successfully competed with, and preyed upon, the less organized biotic association of the pelagic holon, in generally benign locales. The benthic holon tended to have K-properties (Ricklefs, 1973), defined appropriately at an ecosystem level of organization, and the pelagic holon tended to have r-properties. Thus the benthic holon was generally more effectively, and more fully self-regulatory than was the pelagic holon. Following disturbances of a particular holon, r species would thrive comparatively well until the recovery or maturational process again suppressed them partially.
Through comparative limnology studies of lakes it has long been noted that the association of benthic biota appears to be dominant over the pelagic association in strongly oligotrophic, clear lakes. The reverse appears to be true in strongly eutrophic and hypertrophic, turbid lakes. Consistent with such inferences the natural tendencies within lakes, in benign environments, like the Great Laurentian River, is toward oligotrophication. That is unless it is driven through external stresses to a "pathological" self-reinforcing state, which is effectively a disorganized state resembling that of a laboratory chemostat, in which the benthic holon is severely depressed, in part by the "blanketing" effect of the burgeoning pelagic holon (see below).
Other factors than nutrient loading can have an effect that may superficially resemble eutrophication through phosphate loading. These include the other variables in the model of eutrophication by Vollenweider (1968, 1990), e.g. decreasing the depth of water, especially if these kinds of changes occur more rapidly than the adaptive processes can accommodate. Still other factors may include the entry of new exotic r-type pelagic fish species in a lake which previously had few fish species that were effective and efficient in a pelagic role.
In conventional limnology, deeper waters which stratify vertically due to temperature-related phenomena in summer and in winter are usually perceived to have two subsystems during periods of stratification: the epilimnetic and the hypolimnetic. Such an annual cycle may be perceived to have two "bifurcation points", in late spring and in late fall, with two "coalescing points" in early spring and in early fall. So the cycle consists of one vertically-mixed holon in spring and again in fall, and of two vertically-stacked holons in summer and in winter. This additional complexity is scientifically and practically important, but is not addressed in what follows here.
With the above as a selective review of an earlier section, some effects of various major cultural stresses on this two-holon ecosystem, i.e. benthic and pelagic, will now be sketched.
Two hundred years ago, almost all parts of the Great Laurentian River were dominated by a largely pristine version of the benthic holon. Small parts still possess "heritage areas" that have not been radically transformed (e.g. Long Point, Francis et al., 1985) and now provide a basis for imagining what other ecosystems were like in a pristine state. No one has attempted to reconstruct a comprehensive account of all of the pristine Great Laurentian River, but many partial characterizations have been published.
Many kinds of cultural stresses, of increasing geographic scale and intrusive intensity, were applied deliberately or carelessly in these waters. These stresses were mostly applied immediately into the physical space of the benthic holon - into the "shell of the bowl" itself - or quickly settled into it, i.e. in the lower tributaries, coastal zone, riparian edge, littoral benthic and profundal benthic zones. For decades, the growing stresses, which were technologically unsophisticated and thus were not excessively unnatural, were partly "accommodated" by the benthic holon. With increasing strain, deformity and incapacitation, the "adaptive capacity" of the benthic holon was progressively impaired, and apparently became gradually less effective in absolute terms. The progressive suppression of the benthic holon permitted the expansion of the pelagic holon, into parts of the bowl-shaped space that were once the "spatial property" of the benthic holon.
Some stresses appear to have triggered positive feedback or self-organizational processes within the pelagic holon.
The general inference from all of the above is that a variety of cultural stresses acted progressively to suppress the pristine, benthic holon and to foster an artificial, pelagic holon, and that a variety of self-organizational phenomena emerged to exert positive feedback, or to interact synergistically, to consolidate ecosystemic dominance of the pelagic holon over the benthic holon. Parts of the Basin's aquatic ecosystem underwent degrading FLOPs (see previous section), with the emergence of a relatively undesirable, pelagic holon to dominate a debased benthic holon at some time in the 1940s and 1950s. Attempts to date these FLOPs have apparently not yet been made.
Some cultural practices may have acted to limit the degree of dominance by the pelagic holon, prior to explicitly rehabilitative or mitigative measures, such as the introduction and annual stocking of Pacific Salmon which preyed on the small exotic pelagics that had become pests for several reasons. Commercial fishing for rainbow smelt and the alewife may have had mitigative effects of this type, coincidentally.
Incidentally, a FLOP may have developed over a period of years in which increasing symptoms, or partial FLOPs or FLUTTERs, appeared episodically, with a final consummation a decade or so after the appearance of the first strong symptoms. Something similar may occur with FLUPs.
Some rehabilitative practices got underway slowly in the 1950s, i.e. sea lamprey control, reduction in loadings of heavy metal toxics by industries, and of biodegradable organics from sewage outfalls. More followed in the 1960s - reduction in loadings of persistent pesticides, reduction in the intensity of commercial fishing, and the introduction of predatory pelagic salmonines. These were only effective in reducing the rate of expansion and intensification of the emergent pelagic holon. Other stresses kept building, such as loading of hazardous contaminants, loading by phosphates from newly-invented detergents, and destruction of coastal wetlands. With gradual implementation of remediation and rehabilitation plans, a reversal in the relative status of the two holons may become clearly apparent in the 1990s. FLUPs may already have happened in several southerly parts of the Great Laurentian River, e.g. in the Bay of Quinte and Western Lake Erie. The exotic zebra and quagga mussels may contribute to ecosystemic transformations, but whether the unprecedented type of ecosystem that then emerges will be considered an improvement over a degraded eutrophic ecosystem remains to be discovered.
Most of the major cultural stresses are diminishing in intensity, according to many kinds of monitoring data. Exceptions may include temperature increases, due to climate warming caused by a build-up of heat-trap gases in the atmosphere, and increases in ultraviolet irradiation, due to reductions in the stratosphere's ozone concentration caused by a build-up of chlorofluorocarbons. Little attention has been directed to the question of whether these will affect the benthic and pelagic holons differentially with respect to the relative dominance of one over the other. In any case, direct effects on the aquatic ecosystem of increases in basin-wide temperature and ultraviolet irradiation have not been reported, so only forecasts from environmental effects assessments are yet available. It has been suggested that climate warming will on balance act synergistically with other cultural stresses, and thus benefit the pelagic over the benthic holon (Regier, 1993b), but increased ultraviolet irradiation may have an opposite effect due to harm to phytoplankton. On the whole, the set of earlier cultural stresses that led to the dominance of the pelagic over the benthic, especially in the more southerly parts of the Basin, are waning, but at a decreasing rate as levels considered to be acceptable are being approached. Whether the new cultural stresses will interact synergistically to cause a major new type of ecosystem degradation is unknown.
The artificial, pelagic associations of fish, (i.e. exotic salmonids-clupeids-osmerids in erstwhile oligotrophic systems and percids-clupeids-osmerids-percichthyids (of which the percids and one percichthyid were native) in the more eutrophic systems), are waning in absolute and relative abundance. Benthic associations of fish, and benthic life styles within the adaptable species, are becoming more abundant and expanding their domains of dominance. Water is getting clearer. Aquatic macrophytes are more abundant in shallow waters that have become clearer.
The introduction of certain exotic species may be acting synergistically with the general rehabilitative process, with respect to the relative dominance of the benthic and pelagic holons. The zebra and quagga mussels appear to be suppressing biota of both holons, but may on balance affect adversely the pelagic more than the benthic holon. The exotic ruffe, a small benthic species, may prey more intensely on the eggs of pelagic fish species than of benthic species and thus help to limit the pelagic holon. Meanwhile efforts to rehabilitate marshes and wetlands in various shallow areas are expressly directed to fostering the benthic holon and to suppressing the pelagic holon.
As is clear to the experts responsible for planning and implementing remedial action plans and lakewide management plans, the desired rehabilitative/restorative FLUPs will not lead to ecosystems that closely resemble the pristine ecosystems that once thrived there. Apparently no-one now has sufficient expertise to forecast the outcome of any rehabilitative process to any degree of detail. Some ecosystemic self-organizing capabilities - both natural and cultural - will emerge de novo as a result of a FLUP and these will influence strongly the outcome of the rehabilitative efforts. The canon for such a rehabilitated holon cannot be pre-programmed fully or predicted closely, - ambitious attempts to do so would involve pointless expenses. As rehabilitated states emerge in different parts of the Great Laurentian River, separate and comparative studies will provide an understanding of important parts of these canons.
We then sketched Koestler's version of General Systems Theory, GST, which is generally compatible with the versions by Bertalanffy (1952), Rapoport (1986) and others, and involves a degree of complexity for beyond the earlier systems work in cybernetics. Recent developments in ecology by Allen & Starr (1982), O'Neill et al. (1986), Allen & Hoekstra (1992), tend to be detailed elaborations and further developments of the work of Koestler, Rapoport, Bertalanffy and the other early students of open versions of GST, as related to the field of ecology, in which none of the earlier GST leaders were expert.
The concept of a two-holon catastrophe model with benthic and pelagic attractors was then developed. This model appears to us to be implicit in the work of Margalef (1968), Vollenweider (1968), Regier & Henderson (1973) and is explicit with respect to a certain type of shallow water in Scheffer et al. (1993). This model was applied here to describe relatively rare phenomena in nature, and rather more common phenomena with respect to effects of human cultural practices on aquatic ecosystems. The two-attractor model was then used as a perspective on major ecosystemic changes in parts of the Great Laurentian River through two centuries of time.
The relatively simple catastrophe model appears to relate about equally well to the more river-like and the more lake-like parts of the Basin's aquatic system. The tentative inferences of the present sketch could be developed further in a careful manner with respect to the partial generalizations sketched above and then tested with available data. It can readily be made more complex by incorporating an annual dimixis cycle with partial separation seasonally between epilimnetic and hypolimnetic holons, each with some self-organizing capabilities.
It may be that this general approach would provide a way to summarize in a coherent way much information that is now treated as relatively unrelated. Syntheses like this need to be undertaken soon, or much relevant information already collected and partially explained will slip into disuse and be lost to science and practice.
In a companion paper to this sketch of empirical generalizations and theoretical concepts, we will explore further the relevance of recent developments in the post-normal science of complexity to such phenomena. We are developing a holarchic ecosystem analysis/synthesis scheme which provides a framework for categorizing the major influences, and the visible responses, of ecosystems through the ecosystem's self-organizing behaviour. The notion of canon, as a description of the thermodynamic and information processes which constitute the ecosystem under study, and in particular how the constraints on these processes, imposed by available mass, energy and information resources and the environmental context, define the canon, will be examined. It is our hope to move from the present stage of development of these ideas, that is a descriptive, heuristic notion for general visioning, learning, and planning purposes, to an operational tool for making practical plans and decisions.
Acknowledgments
For advice, encouragement and assistance we thank J. Barica, C.H. Fernando, J.F. Koonce, C.K. Minns, R.G. Randall, W.D. Taylor and numerous other colleagues. An earlier version of this paper was presented by the first author as the 1993 Richard A. Vollenweider lecture at the Canadian Center for Inland Waters, Burlington, Ontario, Canada.
Allen, T. F. H.; Hoekstra, T. W., 1992. Toward a Unified Ecology. New York: Columbia University Press, 384pp.
Balon, E.K., 1975. Reproductive guilds of fish: a proposal and definition. Journal of the Fisheries Research Board of Canada 32: 821-864.
Balon, E.K., 1981. Additions and amendments to the classification of reproductive styles in fishes. Environmental Biology of Fish 6: 377-389.
von Bertalanffy, L., 1952. Problems of life; an evaluation of modern biological thought.
.London, Watts, 216pp.
Brandt, S.B., J.J. Magnuson & L.B. Crowder, 1980. Thermal habitat partitioning by fishes in Lake Michigan. Canadian Journal of Fisheries and Aquatic Science 37: 1557-1564.
Caddy, J.F., 1993. Toward a comparative evaluation of human impacts on fishery ecosystems of enclosed and semi-enclosed seas. CRC Press, Reviews in Fisheries Science 1(1): 57-95.
Cairns, J., Jr., G.R. Lanza & B.C. Parker, 1972. Pollution-related structural and functional changes in aquatic communities with emphasis on freshwater algae and protozoa. Proceedings of the Academy of Natural Sciences of Philadelphia. 124: 79-127.
Colby, P.J. (ed.), 1977. Proceedings of the 1976 Percid International Symposium (PERCIS). Journal of the Fisheries Research Board of Canada 34(10): 1445-1999.
Davidson, M., 1983. Uncommon Sense: The Life and Thought of Ludwig von Bertalanffy (1901-1972), Father of General Systems Theory. J.P. Tarcher, Los Angeles.
Fernando, C.H., 1994. Zooplankton, fish and fisheries in tropical freshwaters. Hydrobiologia 272: 105-123.
Fernando, C.H. & J. Holcik., 1991. Fish in reservoirs. Internationale Revue gesamte Hydrobiologie 76(2): 149-167.
Francis, G.R., A.P. Grima, H.A. Regier & T.H. Whillans, 1985. A Prospectus for the Management of the Long Point Ecosystem. Technical Report No. 43, Great Lakes Fisheries Commission, Ann Arbor, Michigan, 109 pp.
Frey, D.G., 1990. What is a lake? Verhandlungen internationale Verein der Limnologie 24: 1-5.
Harris, H.J., 1994. The status of restoration science: aquatic ecosystems. In: Proceedings of a Symposium in Ecological Restoration, March 2-4, 1993, Terrene Institute in co-operation with the US EPA. Great Lakes Regional Office, Washington, D.C. pp. 11-19.
Harris, H.J., V.A. Harris, H.A. Regier & D.J. Rapport, 1988. Importance of the nearshore area for sustainable redevelopment in the Great Lakes with observations in the Baltic Sea. Ambio 17: 112-120.
Hartig, J.H. & J.R. Vallentyne, 1989. Use of an ecosystem approach to restore degraded areas of the Great Lakes. Ambio 18: 423-428.
Hickling, C.F., 1961. Tropical Inland Fisheries. Longmans, London, 287 pp.
Holling, C.S., 1986. The resilience of terrestrial ecosystems: local surprise and global change. In: W.C. Clark & R.E. Munn (eds.), Sustainable Development of the Biosphere. pp. 292-317. Cambridge University Press, Cambridge, U.K., vi + 491 pp.
Huseyin, K., 1977. The Multiple-Parameter Stability Theory and Its Relation to Catastrophe Theory. Branin, F. H.; Huseyin, K., Eds. Problem Analysis in Science and Engineering. : Academic Press; pp. 229-255.
Jørgensen, S., 1992. Integration of Ecosystem Theories: A Pattern. London: Kluwer. 383 pp.
Kay, J.J., 1984. Self-organization in living systems. Ph.D. Thesis, Systems Design Engineering, University of Waterloo, Waterloo, Ontario. 458 pp.
Kay, J.J., 1991. A nonequilibrium thermodynamic framework for discussing ecosystem integrity. Environmental Management 15(4): 483-495.
Kay, J.J., 1993, "On the Nature of Ecological Integrity: Some Closing Comments" in S. Woodley, J. Kay, G. Francis (Eds.), Ecological Integrity and the Management of Ecosystems, St. Lucie Press, Delray, Florida. pp.201-212
Kay, J.J. & E. Schneider, 1994. Embracing complexity, the challenge of the ecosystem approach. Alternatives 20(3): 32-39.
Koestler, A., 1978. Janus: A Summing Up. Hutchinson of London, London, vii + 354 pp.
Lee, G.F. & R.A. Jones, 1991. The effects of eutrophication on fisheries. CRC Press, Reviews in Aquatic Sciences 5: 287-305.
Loftus, K.H. & H.A. Regier, 1972. Introduction to the Proceedings of the 1971 Symposium on Salmonid Communities in Oligotrophic Lakes. Journal of the Fisheries Research Board of Canada 29: 613-616.
Margalef, R., 1968. Perspectives in Ecological Theory. University of Chicago Press, Chicago, 111 pp.
Margalef, R., 1990. Limnology: reconsidering ways and goals. In: R. de Bernardi, G. Giussani & L. Barbanti (eds.) Scientific Perspectives in Theoretical and Applied Limnology. pp. 57-76, Memorie dell'Istituto Italiano di Idrobiologia Dott. Marco de Marchi. Verbania Pallanza, Italy, Consiglio Nazionale delle Ricerche Istituto Italiano di Idrobiologia. 378 pp.
McCormick, M.J., 1990. Potential changes in thermal structure and cycle of Lake Michigan due to global warming. Transactions of the American Fisheries Society 119: 183-194.
Minshall, G.W., K.W. Cummins, R.C. Petersen, C.E. Cushing, D.A. Burns, J.R. Sedell & R.L. Vannote, 1985. Developments in stream ecosystem theory. Canadian Journal of Fisheries and Aquatic Sciences 42: 1045-1055.
Murphy, R., 1994. Rationality and Nature: a Sociological Inquiry into a Changing Relationship. Westview Press, Boulder, Colorado, xiii + 294 pp.
O'Neill, R.V., D.L. DeAngelis, J.B. Waide & T.F.H. Allen, 1986. A hierarchic concept of ecosystems. Princeton University Press, Princeton, N.J., 253 pp.
Petersen, G.H. & M.A. Curtis, 1980. Differences in energy flow through major components of subarctic, temperate and tropical marine shelf ecosystems. Dana 1: 53-64.
PLUARG (Pollution from Land Use Activities Reference Group), 1980. Pollution in the Great Lakes Basin from Land Use Activities. International Joint Commission, Ottawa, Ontario and Washington, D.C.
Randall, R.G., J.R.M. Kelso & C.K. Minns, 1995. Fish production in freshwaters: are rivers more productive than lakes? Canadian Journal of Fisheries and Aquatic Sciences 52: 631-643.
Rapoport, A., 1986. General System Theory: Essential Concepts and Applications. Tunbridge Wells, Cambridge, Mass., viii + 270 pp.
Rapport, D.J., H.A. Regier & T.C. Hutchinson, 1985. Ecosystem behavior under stress. American Naturalist, 125: 617-640.
Regier, H.A., 1993a. The notion of natural and cultural integrity. in S. Woodley, J. Kay, G. Francis (Eds.), Ecological Integrity and the Management of Ecosystems, St. Lucie Press, Delray, Florida. pp.3-18.
Regier, H.A., 1993b. Strategies to adopt to climate warming in the Great Lakes-St.Lawrence River Basin with emphasis on fish and fisheries. In: L. Mortsch, G. Kosbida & D. Tavares (eds.), Proceedings of the Great Lakes-St.Lawrence Project Workshop on "Adopting to the Impacts of Climate Change and Variability", Quebec City, February 9-11, 1993. Environment Canada, Atmospheric Environment Service, Downsview, Ontario.
Regier, H.A. & H.F. Henderson, 1973. Towards an ecological model of fish communities and fisheries. Transactions of the American Fisheries Society 102: 56-72.
Regier, H.A., P. Tuunainen, Z. Russek & L.E. Person, 1988. Rehabilitative redevelopment of the fish and fisheries of the Baltic sea and the Great Lakes. Ambio 17: 121-130.
Regier, H.A., R.L. Welcomme, R.J. Steedman & H.F. Henderson, 1989. Rehabilitation of degraded ecosystems. In: D.P. Hodge (ed.) Proceedings of the International Large River Symposium. pp. 86-97, Canadian Special Publication in Fisheries and Aquatic Sciences 106.
Regier, H.A., J.J. Magnuson & C.C. Coutant (convenors), 1990. Proceedings of Symposium on Climate Change and Fish, Toronto, September 1988. Transactions of the American Fisheries Society 119.
Regier, H.A., & E. Bronson,1992. New Perspectives on Sustainable development and barriers to relevant information. Environmental Monitoring and Assessment 20: 111-120.
Reynoldson, T.B. & A.L. Hamilton, 1993. Historic changes in populations of burrowing mayflies (Hexagenia limbata) from Lake Erie based on sediment tusk profiles. Journal of Great Lakes Research 19: 250-257.
Ricklefs, R.E., 1973. Ecology. Chiron Press, Newton, Mass., x + 861 pp.
Rosemarin, A., 1988. Sustainable Redevelopment of Baltic Sea and the Great Lakes. Ambio 17(2).
Ryther, J.H., 1969. Photosynthesis and fish production in the sea. Science 166: 72-76.
Scheffer, M., S.H. Hosper, M-L. Meijer, B. Moss & E. Jeppesen, 1993. Alternative equilibria in shallow lakes. TREE 8(8): 275-279.
Schneider, E.D & J.J. Kay, 1994a. "Life as a Manifestation of the Second Law of Thermodynamics", Mathematical and Computer Modelling, Vol 19, No. 6-8, pp.25-48.
Schneider, E.D. & J.J. Kay, 1994b "Complexity and Thermodynamics: Towards a New Ecology", Futures 24 (6) pp.626-647, August 1995
Sedell, J.R., R.J. Steedman, H.A. Regier & S.V. Gregory, 1991. Restoration of human impacted land-water ecotones. In: M.M. Holland, P.G. Risser & R.J. Naiman (eds.), Ecotones: The Role of Landscape Boundaries in the Management and Restoration of Changing Environments. pp. 110-129, Chapman and Hall, New York, viii + 142 pp.
Selye, H., 1974. Stress without Distress. J.B. Lippincott Co., New York, 171 pp.
Steedman, R.J., 1988. Modification and assessment of an index of biotic integrity to quantify stream quality in southern Ontario. Canadian Journal of Fisheries and Aquatic Science 45: 492-501.
Steedman, R.J. & H.A. Regier, 1987. Ecosystem science for the Great Lakes: perspectives on degradative transformations. Canadian Journal of Fisheries and Aquatic Science. 44 (Suppl.2): 95-103.
Stephenson, T.D., 1990. Fish reproductive utilization of coastal marshes of Lake Ontario near Toronto. Journal of Great Lakes Research 16: 71-81.
Ulanowicz, R.E., 1986. Growth and Development: Ecosystem Phenomenology. Springer Verlag., New York, ix + 203 pp.
Ulanowicz, R.E., 1989. A phenomenology of evolving networks. Systems Research 6: 209-217.
Ulanowicz, R.E. & J.H Tuttle, 1992. The trophic consequences of oyster stock rehabilitation in Chesapeake Bay. Estuaries 15(3): 298-306.
Vallentyne, J.R., 1974. The Algal Bowl: Lakes and the Man. Miscellaneous Special Publication, 22, Canada Department of Environment, Fisheries and Marine Service, Ottawa, 185 pp.
Vannote, R.L., G.W. Minshall, K.W. Cummins, J.R. Sedell & C.E. Cushing, 1980. The river continuum concept. Canadian Journal of Fisheries and Aquatic Sciences 37: 130-137.
Vollenweider, R.A., 1968. Scientific fundamentals of the eutrophication of lakes and flowing waters, with particular reference to nitrogen and phosphorus as factors in eutrophication. Paris, Organization for Economic Cooperation and Development.
Vollenweider, R.A., 1990. Eutrophication: conventional and non-conventional considerations and comments on selected topics. In: R. De Bernardi, G. Giussani & L. Barbanti (eds), Scientific Perspectives in Theoretical and Applied Limnology. pp. 77-134, Memorie dell'Istituto Italiano di Idrobiologia Dott. Marco de Marchi. Verbania Pallanza, Italy, Consiglio Nazionale delle Ricerche Istituto Italiano di Idrobiologia. 378 pp.
Westley, F., 1995. Governing design: the management of social systems and ecosystem management. In: L.H. Gunderson, C.S. Holling & S.S. Light (eds.), Barriers and Bridges to the Renewal of Ecosystems and Institutions. pp. 391-427, Columbia University Press, New York. xii + 593 pp.
Wetzel, R.G., 1990. Land-water interfaces: metabolic and limnologic regulators. Verhandlungen internationale Verein der Limnologie 24: 6-24.
Whillans, T.H., 1979. Historic transformations of fish communities in three Great Lakes bay. Journal of Great Lakes Research 5: 192-215.
Back to JK publication page