Missing the link: the importance of keeping ecosystems intact and what the Endangered Species Act suggests we do about it.

• Author: Robbins, Kalyani

1. INTRODUCTION II. BACKGROUND A. Listing Species Under the ESA B. Defining "Species" to Include "Distinct Population Segments" C. The DPS Policy III. SPECIES INTERACTIVITY AND ECOSYSTEM FUNCTIONING A. While You Were Sleeping B. Waking Up: Scientists Are Analyzing These Data and Providing Good Food for Policy 1. Keystone Species a. Top Predators b. Ecosystem Engineers c. Competitors and Facilitators 2. Species Interactivity on a Continuum IV. THE DPS POLICY MUST BE CHANGED TO CONSIDER A POPULATION'S SIGNIFICANCE TO ITS ECOSYSTEM A. Individual Ecosystem Survival: Why Should We Care? B. What Needs To Be Changed and How C. Why This is Practicable D. Context, and Why the DPS Policy is the Best One for Applying This Science V. THE LAST WORD I. INTRODUCTION

   The very first goal Congress expressed in the "Purposes" subsection of the Endangered Species Act (1) was "to provide a means whereby the ecosystems upon which threatened and endangered species depend may be conserved." (2) This clear statement, much like the recognition of species' "ecological" value, (3) demonstrates an understanding of the interdependence of species and their ecosystems, as well as a corresponding intent to protect both. Indeed, one cannot be saved without the other.

   In spite of how clearly Congress expressed its intent to conserve ecosystems in the text of the Act, the U.S. Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS), the agencies charged with administering the Act, claim that they have no authority to do so. (4) Granted, most of the Act is focused on direct species protection via the process of listing certain species for special protections. (5) However, in 1978, Congress amended the Act in a manner that had the potential to fill the void in ecosystem protection by allowing one population of a given species to be separately listed while leaving the rest of that species (perhaps healthy in other regions) unprotected. (6) Species can be of varying value to their ecosystems, which should be treated as an important consideration in protecting individual populations.

   The goal of this Article is to combine consideration of the purposes of the Endangered Species Act (ESA) with an understanding of the science of ecosystem functioning in order to promote better policy. Part II of this Article will provide some of the background information needed for a basic understanding of the regulatory framework at issue throughout the Article. Then, in Part III, I will provide a relatively in-depth discussion of the complexities of ecosystem science, in a manner accessible to non-scientists (like myself), in the hope that better understanding will lead to a greater willingness to change policy. Part IV will apply this science to determine how we might best work toward the goals of the ESA, making a case for better protection of ecosystems and suggesting how to go about it. The Article will then conclude with a plea for policy change in light of the previous discussions.

2. BACKGROUND

   1. lasting Species Under the ESA

      The ESA was enacted in 1973 as the first comprehensive U.S. effort to preserve biodiversity. (7) While there are other components to the statute, the one most relevant to this discussion is the process created for listing threatened or endangered species to recieve substantial protections via the various other provisions in the Act. (8) The power to list these species belongs to the Secretary of the Interior and the Secretary of Commerce, who have delegated that power to FWS and NMFS, respectively (collectively "the Services"). (9) Getting on this list is an extremely important achievement because once a species is listed its preservation becomes more important than competing economic interests. (10)

      A species is endangered if it "is in danger of extinction throughout all or a significant portion of its range," (11) and it is threatened if it "is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range." (12) In determining whether a species fits into one of these two categories, the Services must consider five factors:

      (A) the present or threatened destruction, modification, or curtailment of its habitat or range;

      (B) overutilization for commercial, recreational, scientific, or educational purposes;

      (C) disease or predation;

      (D) the inadequacy of existing regulatory mechanisms; or

      (E) other natural or manmade factors affecting its continued existence. (13)

      This, of course, leaves the very important threshold question of what constitutes a "species," which is no simple matter, even among scientists. (14)

   2. Defining "Species" to Include "Distinct Population Segments"

      The Act's original definition for the species it set out to protect included "any subspecies of fish or wildlife or plants and any other group of fish or wildlife of the same species or smaller taxa in common spatial arrangement that interbreed when mature." (15) Thus, it did not provide for individual populations to be listed separately from the remainder of their species. There are two obvious flaws with such an arrangement. First, once a species is listed it would generally be protected across the board, regardless of its varying population densities. (16) This would have the inefficient consequence of protecting members of the species that rived in areas well-populated by that species, in the event that it was in trouble in a significant portion of its range. The second flaw was that the focus on each species as a whole ignored the protection of ecosystems upon which many species (including humans) rely.

      Fortunately, or so it might have seemed, it was not long before Congress amended the ESA in a manner which had the potential to resolve both of these problems. (17) The definition of species has since included "any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature." (18) By allowing different populations of the same species to be treated differently for conservation purposes, Congress provided the Services with an effective tool for ecosystem preservation, as some ecosystems may depend far more heavily on a given species than others. (19) Unfortunately, the Services take a far more conservative approach in implementing the 1978 Amendments' addition of the distinct population segment (DPS) concept. (20)

   3. The DPS Policy

      Although Congress amended the ESA to include DPSs in 1978, it was not until 1996 that the Services published a clear policy as to how they would determine whether a population qualified as a DPS. (21) The Policy contains three evaluative steps, each one serving as a prerequisite to consideration of the next.

      First, the Services will consider the "[d]iscreteness of the population segment in relation to the remainder of the species to which it belongs." (22) Discreteness of a population may be based on its being either "markedly separated from other populations of the same taxon as a consequence of physical, physiological, ecological, or behavioral factors;" or "delimited by international governmental boundaries" where there are significantly different regulatory protections. (23)

      Next, and only if the Services have determined a population to be discrete, they will evaluate "[t]he significance of the population segment to the species to which it belongs." (24) Significance, by far the more controversial factor, is determined based upon the following four criteria:

      1. Persistence of the discrete population segment in an ecological setting unusual or unique for the taxon,

      2. Evidence that loss of the discrete population segment would result in a significant gap in the range of a taxon,

      3. Evidence that the discrete population segment represents the only surviving natural occurrence of a taxon that may be more abundant elsewhere as an introduced population outside its historic range, or

      4. Evidence that the discrete population segment differs markedly from other populations of the species in its genetic characteristics. (25)

      It is only then, once a DPS has been found to be both discrete and significant, that the Services move on to the third step and consider the population's conservation status under the ESA, in the same manner as with species in general. (26) In other words, they will next consider the five factors listed at the beginning of this Part.

      Although the wisdom of this Policy will be discussed at greater length in Part IV, it is worth pointing out, before getting into the scientific discussion, that this significance test is extremely narrow, in that it only allows for consideration of the population's value to its own species. This is in spite of the clearly stated purpose of protecting ecosystems. (27) the requirement to use "the best scientific and commercial data available," (28) and the well-established principles of ecosystem function discussed below. The Services defend this narrow view of significance by citing to a comment made by a subsequent Senate committee that the DPS authority should be used "sparingly." (29) However, as one federal court has pointed out, this statement is "subsequent legislative history" that cannot "support[] the argument that a prior Congress intended the Services to use the DPS authority 'sparingly.'" (30) Nor should sparing use require the Services to ignore the most significant needs of ecosystems. As we shall see, the DPS-listing authority could still be used sparingly if based on ecosystem science.

3. SPECIES INTERACTIVITY AND ECOSYSTEM FUNCTIONING

   1. While You Were Sleeping

      My son, a toddler, has a board book called While You Were Sleeping, which takes him all over the world to see what various creatures were up to while he was snug in his bed. (31) It is truly amazing, for young and old alike, to think about how much activity there is around the world at any given moment. The following are just a few of...