BiologicalIntegrity versus Biological Diversity as Policy Directives Protecting biotic resources Paul L. Angermeier and James R. Karr wo phrases-biologicalinteg- advanced on ecological impacts in rity and biological diversity- Resource would these systems (e.g., Allan and Flecker have joined the lexicon of policy 1993, Schindler 1990), and rates of biologists and natural resource man- be most effective if extinction and endangerment for agers during the past two decades. aquatic fauna exceed those for ter- The importance of these phrases is the goal were the restrial fauna. Among North Ameri- demonstrated by their influence on can animals, for example, Master environmental research, regulatory, protection of (1990) reported that 20% of fishes, and policy agendas. The concepts 36% of crayfishes, and 55% of behind the phrases are central to biological integrity mussels were extinct or imperiled, strategies being developed to sus- compared with 7% of mammals and tain global resources (Lubchenco et birds. Similarly, only 4% of the fed- al. 1991). Unfortunately, the phrases Park Act enunciate the explicit goal erally protected aquatic species in are widely used by the media, citi- of protecting biological integrity. the United States with recovery plans zens, policy makers, and some bi- No specific legislative mandate ex- have recovered significantly, com- ologists without adequate attention ists to protect biological diversity in pared with 20% of protected terres- to the concepts they embody. Pre- the United States, but such protec- trial species (Williams and Neves cise use of the terms integrity and tion became a central goal of the 1992). diversity can help set and achieve 1992 Earth Summit and the Global societal for goals sustaining global Biodiversity Protocol endorsed by Defining biological diversity resources; imprecise or inappro- many nations. The focal positions priate use may exacerbate biotic of the two concepts dictate that a The term biological diversity (or impoverishment-the systematic clear understanding of their mean- biodiversity) emerged as species ex- decline in biological resources ings is critical to developing effec- tinction rates began to increase dra- (Woodwell 1990). tive resource policy. matically (Myers 1979). The specter Although the related concepts of Our review of current concep- of mass extinctions, combined with integrity and diversity were devel- tions of integrity and diversity indi- huge gaps in biological knowledge, oped more or less independently (in- cates that resource policy would be has convinced many scientists that a tegrity in the study of aquatic sys- most effective if based on the more global biological crisis exists (Wil- tems, diversity in the study of comprehensive goal of protecting son 1985). Moreover, because bio- terrestrial systems), both apply to biological integrity. Specific policy logical diversity provides important all biotic systems. The US Clean shifts related to that goal include a aesthetic, cultural, ecological, sci- Water Act and Canada's National reliance on preventive rather than entific, and utilitarian benefits to reactive management and a focus on human society, the crisis is every- Paul L. Angermeieris an assistant unit landscapes rather than populations. one's concern (Ehrlich and Wilson leader at the National Sur- Biological We draw heavily from our experi- 1991). vey, Cooperative Fish and Wildlife Re- ence with but our One of the first formal defini- search of Fisheries aquatic systems, Unit, Department conclusions to terres- tions of termed and Wildlife apply equally biological diversity Sciences, Virginia Poly- trial it "the and technic Institute and State University, systems. variety variability among are and the Blacksburg,VA 24061-0321. James R. Aquatic systems appropriate living organisms ecological Karr is director of the Institute for En- models for illustrating general eco- complexes in which they occur" vironmental Studies, University of logical consequences of anthropo- (OTA 1987, p. 3). In addition, be- Washington, Seattle, WA 98195. genic impacts, because research is cause "items are organized at many 690 BioScience Vol. 44 No. 10 [biological] levels," biodiversity "en- Table 1. Levels of organization in three hierarchies used to characterize biological compasses different ecosystems, spe- diversity. These hierarchies are linked at the species-genome-population levels (see cies, genes, and their relative abun- text for details) but not precisely at any other levels. dance" (OTA 1987, p. 3). Other Taxonomic Genetic Ecological thorough discussions of biodiver- that Biota Genome Biosphere sity confirm multiple organiza- Chromosome set Biome and Kingdom tional levels (e.g., genes, species, Division/Phylum Chromosome Landscape ecosystems) are fundamental to the Class Gene Ecosystem/Community concept (Noss 1990, OTA 1987, Order Allele Population Reid and Miller 1989), thereby dis- Family it from the much sim- Genus tinguishing Species pler concept of species diversity. Hierarchies The dynamics of oak populations in tional level at issue in any discus- a savannah landscape or of fungus sion. In estimating biodiversity in a Organizational hierarchies are use- populations in a stream-channel study area (e.g., a pond or conti- ful tools for understanding complex landscape, for example, may oper- nent), a researcher might count all biological phenomena. Several dis- ate at vastly different spatial scales. the taxonomic elements present, all tinct hierarchies-taxonomic, ge- The appropriateness of a spatiotem- the genetic elements present, or all netic, and ecological (Table 1)-are poral scale for studying a given ele- the ecological elements present. Even relevant to biological diversity. We ment depends on the organisms and in the unlikely event that all the follow Reid and Miller (1989) in questions at issue (Levin 1992). elements present are known, no ac- referring to biotic units at any level At ecological levels of organiza- cepted calculus permits integration within a hierarchy as elements. Thus, tion above population (see Table 1), of counts of elements across levels species and classes are taxonomic spatiotemporal bounds are often within a hierarchy (e.g., phyla and elements, genes and chromosomes arbitrary, integration is often loose, species) or across hierarchies (e.g., are genetic elements, and popula- and composition may be dynamic. species and genes). Arguably, no such tions and biomes are ecological ele- However, these elements are not calculus should be sought. ments. Levels are nested within each random assemblages, and they can Furthermore, the number of ele- hierarchy: a phylum comprises be defined on the basis of ecological ments at different organizational classes, a chromosome comprises attributes and societal benefits. For levels need not be correlated. For genes, and a landscape comprises example, the biota of the Chesa- example, there are more than twice communities. The hierarchies in peake Bay basin is a legitimate ele- as many marine phyla as terrestrial Table 1 are linked at the species- ment of biodiversity because it has phyla, but fewer marine species (Ray genome-population levels; any popu- objectively definable boundaries and and Grassle 1991). Similarly, lation of organisms has a taxonomic confers societal benefits (e.g., fish- Hoover and Parker (1991) found identity (species), which is charac- eries) that would not exist if the that species diversity and commu- terized by a distinct genome. How- component populations had not co- nity diversity of overstory plants ever, taxa may share genetic ele- evolved. were inversely correlated among sev- ments, and ecological elements may We do not distinguish commu- eral Georgia landscapes. In neither share taxa. nity and ecosystem as different hier- example is it unequivocal which sys- Specifying levels within hierar- archical levels but rather as comple- tem has more biodiversity. chies and elements within levels may mentary ways of viewing the same Failure to conceptually integrate be arbitrary. For example, ecolo- system (Karr 1994, King 1993). the multiple aspects of biodiversity gists may add an ecological level for Community perspectives are results in narrowly conceived com- guilds, or taxonomists may debate grounded in evolutionary biology parisons. For example, Vane-Wright the number of families within an and focus on the dynamics of organ- et al. (1991) measured biodiversity order. Because each level and ele- ism distribution and abundance; with an index of taxonomic diver- ment contributes to biotic variety ecosystem perspectives are grounded sity based on cladistics, which as- and value, all are appropriate tar- in thermodynamics and focus on the sesses distinctness of taxa. Similarly, gets of conservation. To focus as- dynamics of energy and materials Mares (1992) used a comparison of sessment or conservation on a single through and around organisms. Ei- mammal diversity (at several taxo- hierarchy or level (e.g., species) is to ther perspective can be applied at nomic levels) among South Ameri- arbitrarily ignore most biodiversity. any level in the ecological hierar- can biomes to infer that biodiversity Spatiotemporal scale is not pre- chy. is greater in drylands than in low- cisely defined by hierarchical level. land Amazon forest. These analyses elements are are Ecological typically Misconceptions valuable, but they cannot be defined by spatial extent (e.g., a interpreted as comprehensive (or pond community or a desert land- Because biological diversity