Dynamic aquaria: building and restoring living ecosystems

166 Pages·2007·9.65 MB·English

by  Walter H Adey, Karen Loveland

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Preface
By the mid-20th century, widespread concerns were being top priority of all human society. It seems highly
expressed for the way in which modern human popula- unlikely, no matter what our scientific and technical
tions and their industrial endeavors and products were prowess, that humans can survive on this planet, with
affecting both the environment in which they lived and our few domesticated species, in the midst of a radi-
the planet’s wild populations and their ecosystems. Some cally altered atmosphere and hydrosphere and a dys-
predictions for the future were dire, and enough environ- functional biosphere. It is most discomforting to hear
mental activism developed so that some of the more of new plans to purposefully inject pollutants into the
conspicuous problems (e.g. raw sewage, oil spills, DDT, stratosphere, to act like a volcanic eruption, or to spray
PCBs, chlorofluorocarbons, and atomic power radioac- iron dust on the oceans, hopefully to increase photo-
tive materials) were subsequently ameliorated or at least synthesis, and thereby, at least temporarily, reduce
subject to management (though never fully corrected). global warming effects. Why is it that so much of our
However, the larger, more widespread, and chronic efflu- educated humanity cannot conceive of working with
ent problems of human society (e.g. nutrients, CO2, and our biosphere, using processes that we know well, to
moderately toxic hydrocarbons) have continued to expand solve multiple environmental problems?
their reach into every corner of the biosphere, atmosphere, Ranging from the domestication of a few wild
and hydrosphere. The ever-growing global human popu- species by chance beginning 10 000 years or more ago
lation, the continuing process of habitat destruction, and to that by design in the last few centuries, human
the ever-expanding desire of that population for a western efforts to extend utilization of our biosphere beyond
lifestyle, rich in fossil energy use and synthesized products, hunter-gathering have almost always been at the level
using abundant raw materials, suggest that these prob- of an individual species. Limited polyculture, as farm
lems, already built up over a century or more, and now ponds, is practiced in some countries, and in the latter
growing geometrically with population expansion, are not half of the 20th century “permaculture,” following
going to be so easily ameliorated. some ancient practices on land, advocated polyculture;
Atmospheric CO2 increase, with its concomitant however, by and large, our domesticates remain mono-
global warming, already seems beyond correction to a cultures. Compared to the global biodiversity (even the
large percentage of scientists, engineers, and educated already greatly reduced biodiversity of today), the
public. Yet, the degradation of our natural waters, and numbers of domesticated species remain vanishingly
especially our oceans, the latter being of considerably small. The intensive management of farms and aqua-
greater mass than the atmosphere, is slower to be rec- cultures provides one of the most extensive elements
ognized; and orders of magnitude more difficult to cor- of coastal and oceanic pollution and wild ecosystem
rect. In many coastal waters, decades of environmental loss. Unfortunately, especially in western cultures, it
effort backed by large financial expenditures have remains deeply ingrained that only by optimizing all
failed to prevent a continuing and serious reduction in aspects of single species culture, often at great environ-
water quality. Although, in many countries, regula- mental cost, can we hope to support current human
tions to contain the widespread pollution of the atmos- populations. It also does not help that most economic
phere and natural waters have been initiated, habitat models call for ever-continuing growth, when this is
destruction continues and increasing population and clearly the root of our failure to meet environmental
advancing prosperity have overcome most efforts to problems.
stem the tide of environmental degradation. As some This book focuses on efforts to interact with and
writers have so succinctly stated, we are slowly begin- effectively “domesticate” at the ecosystem level, to
ning to stew in our own toxic brew. build experimental ecosystems to learn, and to under-
We are hardly alone in expressing our grave concern take ecological engineering, as interaction with “wild”
for the future of the human race if the full understand- ecosystems. Ultimately, we propose to optimize bio-
ing and correction of these issues does not become the geochemical function and biodiversity, and to reform
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xii Preface
our relationship to our biosphere. As we explain in this degradation, and the waters of the Baltic Sea and
book, symbiosis has been a critical part of organic evolu- Chesapeake Bay are considerably more altered than
tion. Likewise, humans have formed a number of sym- those around Tierra Del Fuego. However, as we shall
bioses with plant and animal domesticates. Some very point out in our following text, numerous studies and
influential and critical scientists have recognized that reports declare a global scale alteration of species
the human symbioses collectively called farming have and community function that is likely to continue and
been a mixed blessing for the human race. Nevertheless, deepen. We have written this 3rd edition on the basic
current human populations are demanding an ever- premise that most aquatic ecosystems are no longer
expanding intensive global scale farming that typically “wild,” being subject to significant and negative
uses monocultures to optimize a single return; usually unplanned and uncontrolled human effects. We now
this return is biomass for food, materials, and, more must treat wild ecosystems as controlled systems that
recently, energy. However, the human race also requires must be managed, and human effects ameliorated, just
ecosystem/biosphere level atmospheric and hydros- as in our “captive” ecosystems. We have expanded our
pheric cleaning, soil structuring services, and general earlier treatment of “Building Living Ecosystems” to
biogeochemical stabilization that our farming sym- “Building and Restoring Living Ecosystems,” applying
bioses do not and probably cannot provide. Global much of the original methodology, where appropriate,
warming is only one example of human overpowering to “wild” systems management. We show that large-
of those global ecosystem services. As we describe in scale ecosystem cleaning of human pollution, using
depth in this book, the experimental study of living solar/algal techniques, can also provide considerable
ecosystems can lead to “domesticated” ecosystems that usable energy to replace the fossil fuel use that is
are far more efficient at solar energy capture than farm responsible for much of the global environmental
monocultures, without providing the inevitable envi- degradation. Just as we have organized in the past to
ronmental degradation of those monocultures. We industrialize, we must now re-organize to more fully
demonstrate that use of such systems can clean up much integrate with the Earth’s biosphere while switching to
of the damage already visited on our planet. renewable energy sources.
Significantly increased energy and materials conser- It has been 15 years since the 1st edition of Dynamic
vation is essential to current and future generations. Aquaria was completed; it has gone through several
While this has been locally necessary in the past, as printings, and the response, especially in the academic
many communities and even civilizations have found and professional world, has been quite favorable.
out to their detriment, our great numbers and increasing Some of the model or controlled ecosystems described
individual requirements have now expanded the con- in the 1st edition are still in operation. One system,
servation requirement to a global level. Unfortunately, with its mechanical–electrical systems re-built, has
we are unlikely to achieve the level of conservation now been in operation for over 25 years. A few have
needed to stop the global warming “steamroller,” and been extensively researched, and we can now report
ultimately coastal and oceanic depletion, unless we in depth on their function. Those long-term systems
expand the scale and depth of our photosynthetic sym- that have been carefully studied have shown complex
bioses to both the landscape and the ecosystem level. community and trophic structuring and extraordinary
Some environmentalists will find the thought of domes- biotic diversities based on reproductively maintained
ticating high-diversity, high-efficiency ecosystems as populations.
undesirable, perhaps even encouraging human society The scientific context in which our approach to living
to neglect conservation and population reduction. systems modeling has developed has changed signifi-
Indeed, this is a potential dilemma. However, even if a cantly. In the year Dynamic Aquaria was first published
broad spectrum of human society could be brought into (1991), the journal Ecological Engineering also appeared.
an extensive conservation mode, the inertia of global It has now completed its 15th year and has published
population and degradation provides environmental over 500 articles. Several scientific studies describing the
problems that are realistically beyond a simple conser- approaches of other scientists to living systems model-
vation solution. ing have also appeared during the same time frame, and
In the earlier editions of this book, we presented a more peripherally, but of considerable interest, the
methodology for re-creating functioning wild aquatic Society and journal Restoration Ecology have matured.
ecosystems for research and education. The underlying In the public display/education arena, the
philosophy centered on the notion that many of those Smithsonian exhibit conveying the principles of
ecosystems remained in the “wild state” and that it ecosystem operation to the public at large has now
was possible to re-create or model them experimen- moved to and become the “Smithsonian Marine
tally. Clearly, there is a broad gradient of ecosystem Ecosystems Exhibit” at Fort Pierce, Florida. However,
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Preface xiii
very few large public aquaria built during the past 20 the many millions of species in the world, most have
years, unless adjacent to a good and abundant source evolved chemical/ mechanical systems that are of
of high-quality water, have chosen to take an ecological potential use to the human race. Yet, we are forcing
route – for most, the graphic design and artistic back- them into extinction at ever-increasing rates, every day
drop may be ecologically oriented, but the organisms losing forever invaluable information.
displayed are specimens isolated from a real ecology. Maybe one day we will know so much about genetic
This is most unfortunate, because it is only with codes and cellular and organism development that we
broader public understanding that the massive loss of can create de novo any organic possibility; and, on the
diversity, so characteristic of today’s biosphere, can be other hand, maybe that day will be as far away as
halted. This must be accomplished through steward- atomic fusion and artificial photosynthesis. In the
ship of the environment and the ecosystems in which meantime, it behoves the human race to develop as
organisms live by most of our population. The concept many symbioses with species and their ecosystems as
that species can be saved one by one at best applies we can manage. We are an integral part of organic evo-
only to mammals and a few birds and fish, if at all. lution and organic complexity. If we try to escape that
Finally, the hobby world of aquaria remains in fer- fact, a fact as deeply and broadly based as any of our
ment with ideas that still exceed the funding capability scientific and engineering knowledge, and a narrow
of scientific and information systems to test and convey parasitism of a few species, the rest be damned, we
reality. Unquestionably, many new “hobby” techniques, are likely to commit ourselves to early extinction.
both those tested in the garage and those provided by Multimillions of species in the past have failed to adapt
enterprising businesses, are increasingly capable of and traveled that well-worn route. Sooner or later, an
culturing many species under optimum conditions of astronomical event may well cause our extinction.
growth and sometimes reproduction. The recent Reef However, we will just as likely survive a few more mil-
Aquarium “bible” by Delbeek and Sprung is a shining lion years if we will use our intellect to adapt to the
example of progress in the hobby. However, hobby sys- reality of our base in organic evolution.
tems mostly remain polycultures, and real ecosystems, This edition is divided into five broad sections,
consisting of diverse communities of organisms in an each containing two to seven chapters. Most chapters
environment approaching that of a wild analog and begin with a review of the subject matter relative to the
processing energy and nutrients through food webs, larger picture of ecology, ecosystems, and the Earth’s
are rare. biosphere as a whole. Part of our appreciation of
In this edition, we greatly expand on the use of the complexities of smaller ecosystems comes from
ecosystem modeling techniques to clean natural waters understanding the more universal context in which all
and the atmosphere. We also show how large rivers, ecosystems operate. Where appropriate, the remainder
bays, and even the ocean and atmosphere can be man- of each chapter deals with the building of microcosms
aged in a far healthier state, and kept that way, if and mesocosms of ecosystems for research and also
we will only adapt a more conservation-minded and gives examples of the unique aspects of small home
ecosystem-centered approach to the human future. aquarium systems. Finally, where appropriate, we dis-
We briefly discuss a critical area of aquatic ecosys- cuss how the information presented relates to the
tem modeling that is especially ripe and far overdue larger concern of environmental restoration.
for development, namely systems for identification Part I discusses the physical environment, elements
and extraction of pharmaceutical drugs already devel- of which at the ecosystem level have often been mis-
oped by a host of wild species. In our anthropocentric understood by environmental scientists and ignored
arrogance, humans tend to conclude that with our by aquarists and hobbyists. We discuss our further
brains, tool use, and language we are far beyond other understanding of the shapes, material, and construc-
organisms. Humans have long thought of harnessing a tion of the envelope that will hold various size aquaria;
few animal species to “work” for us, and have tried to the temperature, water composition, and motion; solar
co-opt the energy storage of a number of plant species; energy; and the substrate, or rock, mud, and sand, that
however, for many, most life is thought of as useful makes up the floor of the system and in part provides
only to “tree-huggers” and in the way of our for all critical geological storage. We also examine the
“progress.” We tend to forget the story of penicillin, critical role of suspended particulates, inorganic and
and the parallel stories of many lesser known drugs. organic, in aquatic ecosystems. Since it is based in the
Up to a half century ago, serious bacterial infections physical factors discussed in this section, we also pres-
often meant death or dismemberment. Then we ent a biogeographic model for the world’s ocean
learned of and eventually co-opted the chemical coasts. Much ecosystem modeling is likely to be carried
“invention” of penicillin by the fungus Penicillium. Of out within the framework of this model.
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xiv Preface
In Part II, on the biochemical environment, we dis- commensurate with the many years of extensive moni-
cuss the mechanisms of gas and nutrient exchange, as toring data now available. Calcification and biodiver-
well as the management of animal wastes in small sity investigations of the latter, 130-gallon coral reef
models. We particularly examine “ecosystem metabo- system, are covered in Chapter 20.
lism” contrasting the interlocking functions of plants Efforts are now under way to apply the concepts pre-
with animals needed for the successful operation of sented in this book to commercial-scale culture of organ-
these dynamic ecosystems. We continue to describe our isms and the production of human food. Both concepts
primary means of controlling the biochemical environ- will assist in protecting endangered wild communities
ment by using managed communities of algae, and to by greatly reducing wild harvest. Both concepts will cir-
thereby achieve the simulation of larger volumes of cumvent the increasing tendency for wild harvests to
open water and where appropriate export to other com- lose their economic viability. Equally important, the
munities or geological storage. Because biomineraliza- basic water quality control methodologies described in
tion, especially calcification, represents an internal sink this book are applicable to relatively inexpensive and
and needs special treatment in semi-closed ecosystem high-quality treatment of a broad spectrum of both
models, we provide a chapter reviewing what is known human wastewaters and the streams, rivers and bays, as
about this complex subject, and we relate this to the well as coastal waters that are impacted by those waste-
management of controlled ecologies. One of our longer- waters. In Part V, we describe some of the ongoing
lived coral reef models was used to extensively research efforts to make these endeavors commercially viable
this subject. Much of this has been published in scientific and environmentally successful at large scale.
journals, and the basics are presented in Chapter 10. HydroMentia, Inc. of Ocala, Florida, provides the princi-
The ecosystem concept remains a subject of ani- pal commercial effort to expand these methodologies to
mated scientific debate. However, most scientists landscape scale. Some of HydroMentia’s engineering
™
would accept for a definition something approaching processes are proprietary, including the use of ATS for
“diverse communities of organisms, supported and phosphorus and heavy metal removal. Commercial
constrained by a given physical–chemical environment, endeavors should examine the HydroMentia organiza-
interacting to capture and process energy and nutrients tion website and contact their representatives for further
in food webs.” In Part III, we deal with the organisms, information.
their diverse communities, and their food webs. It has Finally, in Part VI, we present a series of principles
been clearly and repeatedly demonstrated that given a for establishing and operating living ecosystems. This
reasonable facsimile of the wild environment, with is where the real scientific learning process begins, in
appropriate imports and exports, and a diverse mix of reducing our endeavors to core concepts, each of which
introduced species of the wild biota, the species of we strive to better understand in the framework of the
ecosystem models will self-organize communities and ecological function of the natural world. Most impor-
food webs to process energy and nutrients. Finally, in tant, we come to understand that the key element to
Chapter 19 of Part III, we introduce symbiosis, and dis- success lies in boundaries, the open end of the defini-
cuss the considerable role that this process has played tion of an ecosystem. No ecosystem stands alone.
in organic evolution. As humans continue to push other Understanding the conditions at the boundaries, the
species “out of our way” and drive ever more of them imports and exports, knowing which species must be
into extinction, it is essential to remember that a sym- simulated by human action because scaling factors
biosis or joining together of organisms has often pro- effectively place them across the boundaries, and,
vided a highly successful evolutionary strategy. finally knowing where to draw the boundaries to make
In Part IV, we present case studies of numerous the modeling effort practical, will determine the mag-
microcosms, mesocosms, and aquaria. Treatment of nitude of success. Restoration of human-impacted wild
the Florida Everglades Mesocosm and the authors’ ecosystems differs primarily in scale; the concepts are
14-year-old 130-gallon coral reef is greatly expanded quite similar.
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Acknowledgments and Dedication
It has been nearly 30 years since we initiated the develop- have been many and their wisdom and effects are
ment of the concepts presented in this book and began always helpful, Pat Kangas has been ever behind the
the long process of R&D that produced the very promis- principles and broader goals. And among our long
ing array of ideas and working systems now in motion. time friends, Susan Bradley has always been ready to
For those who will open their eyes and minds, we speak come to our rescue, whether for a creative design or
of the methods of a new rapprochement with nature. A technical computer problems, while Addie Moray and
generation ago, neither the method of experimenting Mary Ellen McCaffrey gave unselfishly of their time for
with captured ecosystems nor the concept of learning some of the administrative tasks. We say again, a book
from, and then “domesticating” ecosystem processes must teach, and while text is paramount, a picture is
was widely accepted either in the aquarium hobby ever “worth a thousand words.” Again in this edition,
world or in the science and ecological engineering com- photographers Nick Caloyianis and Clarita Berger
munities. As exhilarating as these years have been for us, worked their superb magic to provide what only
they have not been without physical, emotional, and photography can convey.
financial struggles, especially for our far-flung families, The erratic path to knowledge in natural history sci-
students, colleagues, business associates, and financiers. ence is, in the end, ever exciting, and because of the
So many people have helped us, we are losing count, and “ivory tower” environment in which it is carried out,
here we can single out only those who were strikingly we would not wish to lose a moment of it. The applied
important in more recent years. We apologize to the far world, and finding the funding to make it happen, can
more numerous helpers and facilitators that we do not be more brutal. To those engineering colleagues and
specifically mention but without whose assistance the financial and business associates who have not only
accomplishments we present would be far more lim- traveled with us in our efforts to bring the solar energy-
ited. The contributions of many of these individuals are capturing and water and atmosphere cleansing process
mentioned in the earlier editions. of ATS to a very needy world, but also have picked up
To all the members of our families, who have the ball and run up-the-mountain when we have tired,
inevitably lived with Dynamic Aquaria and its precedent we feel a gratitude and comradeship that is inexpress-
research for decades, we thank each of you for your ible. At a time when algae was still a bad word, a cousin
patience (and guidance). Special tribute goes to Nathene to red tide and the failed food promise of the 1950s,
Loveland, Karen’s mother for her encouragement in ini- Don Panoz and Richard Purgason started the ball rolling
tiating the R&D endeavor, and for her enthusiasm and with Aquatic BioEnhancement Systems. We are espe-
multifaceted support, and to Walter Adey Sr., Walter’s cially indebted to the HydroMentia crew, especially
father, for a guide to life that lives on. Whitcomb and Margaret Palmer on the business and
Science and engineering is meant to be questioned, financial side, and Allen Stuart and Mark Zivojnovich
tested and re-tested, but the road of true progress can on the engineering side. The engineering innovations
be long, convoluted and tiresome. To our numerous and managerial devotion of the HydroMentia staff
students and assistants, the energy of youth always to solving these serious environmental problems is
made up for whatever we lacked, and we are deeply extraordinary by any measure; HydroMentia picked
conscious of the gratitude we owe you. We are espe- up the ball when it was slowing and we are now
cially indebted to our longtime friend, colleague, and approaching the goal posts, at least the ones most visi-
student, Sue Lutz; she came to our rescue, to help us ble in the fog of time. Whit especially had the vision,
meet the various deadlines, while we needed to be on interest, and resources to take the chance on this jour-
our research vessel in the Canadian Maritimes; without ney, even when the walls in the fog soared out of sight.
her multifaceted talents we could not have completed We are particularly grateful to both Mark and Allen
this edition. In recent years, Allegra Small and Don who provided their consistent support in supplying
Spoon additionally provided the dedicated support that editing, current data and information for this edition.
was a requirement for success, and while our colleagues Above all, we thank all of you for your friendship and
xv
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xvi Acknowledgments and Dedication
ongoing, stimulating interchanges and discussions. especially Melissa Read, Project Manager, of Elsevier
HydroMentia, this edition of Dynamic Aquaria, is dedi- Book Productions in Oxford, England, Gregory Harris,
cated to you. the Designer for Elsevier, who stuck with us to create a
Organism culture, by sustainable and non-polluting new cover design, and Pat Gonzalez of Academic Press
means, is essential to our future use of organisms from in San Diego, who helped guide us in the initial process
our hydrosphere. However, the “tragedy of the com- of this endeavor.
mons” haunts us, and as long as there are “fish in the The global environment is under siege by an explod-
sea”, the ability to make this shift will be illusory. On ing human populace driven by pre-historic genes.
the ornamental culture side, we have to take our hats However, we can think and reason; we are not the deer,
off to Morgan Lidster for his “green thumb.” However, rabbits, and lemmings who cannot know they are
the financial mountain was overpowering, and we destroying the environment that they depend on and
now put our hopes in SeaQuest of Utah for further are heading for population collapse. We can learn and
motion in this very challenging arena. respond to the challenges. We surely must try, because,
Finally, we thank our publisher Dr. Andy Richford, with our technical prowess and global influence,
Senior Acquisition Editor, Life Sciences Books of humans will hardly be alone in this collapse. We salute
Elsevier and Academic Press in London, for providing all of those who have helped us, and often carried
us the opportunity to expand and broaden our scope in us on our way; we think the ideas expressed herein
this edition, and for the unending enthusiasm and will help in our “coming to terms” with the realities of
encouragement of the Elsevier/Academic Press staff, nature.
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C H A P T E R
21
A Subarctic/Boreal Microcosm
Test of a Biogeographic Model
Including its prototype, a 2600-gallon, 6-square strikingly different biotic character of the western Atlantic
meter microcosm/exhibit of a rocky Maine shore and core Subarctic (northern Gulf of St. Lawrence, NE
marsh was operated successfully for 17 years in the Newfoundland and Labrador) as compared to the mixed
Smithsonian’s National Museum of Natural History in Subarctic/Boreal to the southwest (Nova Scotia and Gulf
Washington, DC. Later in this chapter, that model ecosys- of Maine). This difference we attribute primarily to a
tem is described and compared with the wild ecosystem. geological history that creates lengthy coastlines and a
In 2000, the “Whale Hall,” in which the cold-water Pleistocene long-temperature control of the biota (as
microcosm had resided, was closed for re-development circumscribed by the A/S Model). Thus, the patterns we
of the entire Hall. The coral reef exhibit was moved to the describe are attributed to “bottom-up” factors. Many
Smithsonian’s Laboratory at Fort Pierce, Florida, but other scientists feel that “top-down” factors, or a trophic
unfortunately the Maine shore exhibit was not re-built. cascade created by the intensive fisheries of the region
In the years following the field research that led to the and the role of the green sea urchin (as controlled by
exhibit and the execution of the rocky shore microcosms, those fisheries) are more important (see review, Steneck
Adey and Steneck (2001) published their theoretical and Carlton, 2000). A mesocosm analysis of this basic
biogeographic model of the world’s ocean coasts (a brief problem would provide methodology for understanding
review of that paper and the A/S Model, is given in and perhaps resolving an apparently intractable issue
Chapter 3). The A/S Model has very much changed our (Steneck, 1998); we have developed this presentation
view of the potential application of the cold-water micro- to encourage just such an approach. At the end of the
cosm systems described in this chapter. chapter, we will describe the 17-year-old Maine “living
As we show in Figure 21.1 and Color Plate 33, the model” system. Aminor revision and preferably enlarge-
subtidal biota of the Gulf of Maine would lie not in the ment of this system we feel would provide secure
core Subarctic region of the biogeographic model, but answers to these questions. At the very least, such an
rather in the 50–70% Subarctic transition zone, with endeavor would provide a considerably deeper under-
northeast Atlantic Boreal species providing the remain- standing of the shore ecology of this region.
ing 30–50% of the biota. In this case, the contours shown
are that of crustose coralline cover in the subtidal zones.
As we will demonstrate later, the intertidal and infralit- THE ROCKY, EMBAYED COAST OF THE
toral zones (between spring and neap low tides) of the NORTHWESTERN ATLANTIC
Gulf of Maine (and Nova Scotia) are even more strongly GEOLOGICAL HISTORY
Boreal in their biota.
The initial purpose of this chapter is to briefly describe As permanent bodies of water in essentially
the rather similar structural habitat of the northwestern their present configuration, the Gulfs of Maine and
Atlantic rocky coast that results from a common geologi- St. Lawrence are only 10–12 000 years old. However, they
cal history, especially the glaciation of the last several have been basin-like features of the western Atlantic/
million years. However, we will then demonstrate the North American landscape for at least 3–5 million
371
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372 21. A Subarctic/Boreal Microcosm
FIGURE 21.1 Northwestern North Atlantic coast from Cape Cod to Labrador, showing the relative abundance
(bottom cover) of Subarctic crustose coralline algal species. The contours represent greater than 90%, 95%, and 98%
Subarctic cover and define the core Subarctic as we treat it in this book (see Adey and Steneck, 2001). The addi-
tional coralline cover (to reach 100%) consists of Boreal species in the south and Arctic species in the north.
years. When not filled with glacial ice, they have been ecosystem function. Rocky shores dominate much of
basins and sometimes embayments or gulfs similar to this coast, but bays, mud flats, and marshes are con-
their present shape for much of that time. The basic spicuous, and in deeper-water muddy to gravelly/
ecological character of the Gulfs and the open Atlantic shelly bottoms cover very large areas. Here we will
coast is determined in many ways by its geology. The concentrate on the rocky shores.
composition and orientation of its rocks and the sedi- The northwest North Atlantic coast sits astride the
ments derived from those rocks are clearly crucial in Appalachian Mountain chain built mostly by a complex
their effects on communities of organisms and on of plate tectonic motions from 600 to 250 million years
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The Rocky, Embayed Coast of the Northwestern Atlantic Geological History 373
Oceanography
ago (Chapter 3). The primary basement rocks on much
of the coast are granitic or moderately metamorphosed Unlike most coastal basins, in the Gulf of Maine, the
sedimentary rocks, although in Newfoundland uplifted rivers are short and relatively small. The freshwater
and tilted sedimentary rocks provide for spectacular runoff into the Gulf is minimum, and the Gulf of Maine
sea cliffs and an array of island/bay topography. When is not an estuary. Furthermore, a deep, submerged val-
the proto Atlantic Ocean began to split open about 200 ley (Northeast Channel) was created by plumes of gla-
million years ago (see Figure 3.4), dead-end “side cial ice, as shown in Figure 21.2. This allows deeper
splits” or rifts occurred that were filled largely with continental slope water access into the Gulf (Figure
volcanics or terrestrial sands eroded off the sides of the 21.3). The latter is a relatively warm and salty, nutrient-
rift valleys. This is the origin of the Gulf of Maine, and and oxygen-rich water that largely prevents nutrient
although some of the lava layers are resistant to erosion depletion and is ideal for enhancing primary produc-
and in places can be important in present-day shore- tion. The prevailing and often stiff northwest winds of
lines (Bay of Fundy), mostly these softer rocks are more winter repeatedly blow the surface waters out of the
easily weathered-out. The Gulf of St. Lawrence basin Gulf, resulting in overturn of Gulf of Maine waters
similarly formed during an earlier “Atlantic” opening with slope waters about once a year (Figure 21.4). The
(several hundred million years earlier) that later became prevailing westerly winds and coriolus forces then
filled with flat-lying limestones, remnants of which drive a constant counter-clockwise gyre in the Gulf as
remain as the island of Anticosti and as fringes in the deep, nutrient-rich waters work their way up into the
northern and eastern Gulf. water column and are finally driven offshore.
The same basic types of bedrock or basement rock In its general pattern of circulation and yearly over-
that form the Gulfs and Newfoundland and Nova turn, the Gulf of St. Lawrence is similar to the Gulf of
Scotia are abundantly present from the Hudson River Maine (Figure 21.5). However, it differs in four very
southwest to about the Savanna River, between South important ways: (1) the St. Lawrence River is the 16th
Carolina and Georgia. Even the elongate side rift val- largest in the world, by mean yearly volume; however,
leys, filled with volcanics and sands, are scattered its outflow is largely restricted to the south side of the
along the entire east coast. However, beginning 50–150 Gulf of St. Lawrence as the Gaspe Current, and having
miles inland from the coastline to well offshore, these been thoroughly mixed with salty Gulf water in the big
older rocks were gradually buried under what is now tides of the inner estuary, provides a strong, coastal
hundreds to thousands of feet of younger sediments salinity outflow in the southern part of Cabot Strait.
washed off the Appalachian Mountains and accumu- From there it flows as a coastal current along the Nova
lated since the opening of the Atlantic Ocean. These Scotia coast to become the SSV inflow to the Gulf of
Cretaceous and Tertiary sediments, to about 150 mil- Maine shown in Figure 21.3. (2) The deep water flows up
lion years old, are the same kinds of soft “rocks” that the Laurential channel (equivalent to Northeast Channel
originally buried the now rocky coast to the northeast. current in the Gulf of Maine) is similar to the Maine
Northeast of Long Island, Cape Cod, and the array of Bottom Water in salinity, though a little cooler and
larger and smaller islands that make up the huge ridge denser. However, overlying the deep water is a mid-
of glacial boulders, gravel, and sand that provides the layer of fresher and very cold water, near or below 0°C,
dividing line between the southwest Atlantic coast and that is the lower end of the highly chilled winter water
the northeast coast, these sediments are largely missing. mass in the Gulf. (3) Together these cold-water masses
Some tertiary sediment layers can be found as patches upwell in the outer St. Lawrence estuary, in the area of
in the Gulf of Maine (and consolidated, but largely flat- Pt. des Monts, due to tidal effects and internal waves in
lying mid-Paleozoic limestones and sandstones occur the Gulf against the sharp shallowing of the Laurential
in the Gulf of St. Lawrence). However, most of the sedi- channel in that area. (4) While a large tidal range exists
ment washed off the Appalachian Mountains and laid in the innermost estuary that assists in rapidly mixing
down along the coast since the Atlantic Ocean opened, the river fresh water with that of the relatively high-
has been bulldozed off the coast. The sediments were salinity deep and mid-water, it is effective only over a
pushed to the south and east, repeatedly, over 1–3 mil- small area of the Gulf of St. Lawrence. Most of the Gulf
lion years, by huge masses of moving Pleistocene gla- has a microtide, less than 1 meter in range, and like the
cial ice (Figure 21.2). The dynamic interaction of a Gulf of Maine, most of the Gulf of St. Lawrence is an
bedrock geology formed hundreds of millions of years epicontinental sea and not an estuary.
ago with Pleistocene continental glaciation thus pro- In the Gulf of Maine tectonic forces followed by
duced the physical environment that circumscribes the glaciation have done more than just create a swirling
biogeography that we seek to model. basin that is constantly refilled with offshore water.
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374 21. A Subarctic/Boreal Microcosm
FIGURE 21.2 The Laurentide Ice Sheet at its point of maximum extension; note at 18 000–22 000 years BP, the last or Wisconsinian
glaciation, the ice extent may have been a little more limited on the eastern coasts than what is shown here. Preglaciation stream valleys
had focused repeated glacial erosion during the 1–3-million year Pleistocene. The net result was the carving of broad depressions in softer
rocks, ultimately giving rise to the Gulfs of Maine and St. Lawrence. Plumes of the ice sheet carved out the deep channel entrances to both
Gulfs. From Denton and Hughes (1981). Reprinted by permission of John Wiley & Sons, Inc.
The water mass of the Bay of Fundy is just about the northeaster storms may be fearsome, the fetches are
right size to match the oceanic tidal wave and allow short, the Gulf coasts relatively protected, and giant
very large tides (Chapter 2). This, in turn, creates addi- waves are not nearly the stringent ecological factor that
tional tidal mixing that further limits nutrient deplet- they are on many rocky coasts (e.g. the western shores
ion and prevents the extremes of temperature and of the British Isles).
winter sea ice formation that characterize the Gulf of The northern shore of the Gulf of St. Lawrence, with
St. Lawrence and many other continental embayments west-flowing currents, is largely removed from the more
at high latitude. Furthermore, although the winter dynamic mixing of the inner and southern Gulf. In part,