160 



Invtrlchiaies — Our Liviiifi Ki'Xdiiives 



Leaf miner moth {Acniceivaits 

 urlmhlla). 



Citophilus mealybug 

 (Pseiidococciis calceolariae). 



tVoiii agricultural lands, and contamination of 

 aquatic habitats by toxic substances and acids, 

 invertebrate populations can be severely dam- 

 aged. Airborne toxicants like acid rain are 

 harmful to the long-term well-being of insects. 

 If disturbances are sufficient, natural fauna may 

 be extirpated (removed or lost) and replaced by 

 more tolerant kinds. This "unbalanced" situa- 

 tion usually results in a population explosion of 

 a few species (e.g., Tubiflcidae: Oligochaeta 

 and red-blooded Chironomidae: Diptera). Such 

 a biological reaction makes these aquatic inver- 

 tebrates excellent bioindicalors of overall envi- 

 ronmental conditions (Bartsch and Ingram 

 1959). The use of aquatic invertebrates for 

 bioassay (testing the toxicity of substances to 

 "standard" test organisms) has greatly helped to 

 minimize adverse effects of contaminants on 

 aquatic life. 



Butterllies and moths are particularly sus- 

 ceptible to environmental disturbances (Opler, 

 this section), although their responses to mild 

 disturbances and changes may be slow, lasting 

 decades (Otte, Swengel, and Swengel and 

 Swengel, this section). McCabe (this section) 

 concludes that some of the tlux in biodiversity 

 is likely due to the "edge effect" at the interface 

 from one habitat to another, and not necessarily 

 to anthropogenic (human-caused) disturbances. 



In the aquatic realm, organic chemicals and 

 other toxic substances, acids and alkalis, and 

 mine drainage can quickly decimate popula- 

 tions of mussels, mayflies, and stonetlies. 

 whereas reduced water flow and introduction of 

 pollutants like silt and excessive nutrients 

 (Mason el al.. Webb, this section) cause a slow, 

 relentless destruction of the indigenous fauna. 



In the past 50 years, nearly 72% of the 

 United States' 297 native mussel species have 

 become endangered, threatened, or of special 

 concern (Williams and Neves, this section). 

 Their populations have been damaged because 

 of siltation, point and nonpoint source pollu- 

 tion, and outright habitat destruction. 



The zebra mussel (Dreissemi polynwrpha) 

 and some other nonindigenous species repre- 

 sent "biological pollution" (Schloesser and 

 Nalepa. this section), and should be considered 

 much like toxic pollution for control and treat- 

 ment. Non-native zebra mussels lack predators 

 and have invaded nearly the full length of the 

 Mississippi River and its major tributaries, 

 threatening the native mussel fauna of the east- 

 ern United States (Williams and Neves, this sec- 

 tion). The impact of the zebra mussel and other 

 nonindigenous species is covered in greater 

 detail in the "Non-native Species" section of 

 this report. 



Historical data bases (e.g., Otte, this section) 

 have traditionally focused on commercially 

 important invertebrate species such as clams 



and oysters. In contrast, little infonnation exists 

 on the status and trends of nonconsumptive, 

 indigenous invertebrate life, and existing data 

 are often not in formats for use in modem deci- 

 sion-making tools (Messer et al. 1991 ). 



An important, often-overlooked problem 

 with providing scientifically credible data 

 involves the taxonomy and systematics (identi- 

 fication and classification) of organisms. Today, 

 our museum collections of invertebrates are 

 often old and worn out, and there are few 

 trained taxonomists to renew archival materials. 

 In fact, many "type" specimens used for origi- 

 nal species" descriptions in the early I900's are 

 unusable, making comparisons of recently col- 

 lected specimens impossible. 



Canada has been doing continuous biomoni- 

 toring for several decades, which has now 

 resulted in status and trends analyses of subtle 

 perturbations like acidification (Chmielewski 

 and Hall 1993). It is clear that the success of 

 future assessments in the United States will 

 greatly depend on availability of and access to 

 high-quality data; stop-gap measures are unlike- 

 ly to prove successful because of inconsisten- 

 cies caused by differing collection methods, 

 taxonomy, and reporting units. 



This section is organized by general articles 

 on inveilebrates and followed by terrestrial and 

 aquatic case studies. The authors drew on orig- 

 inal data, often unpublished, and therefore, 

 although some of the studies may appear out- 

 dated, this does not detract from the usefulness 

 of the examples. 



Basic research on the taxonomy and ecology 

 of species and communities is urgently needed 

 as groundwork for future status and trend 

 assessments. Complex ecological relationships 

 are poorly understood. Only a few working 

 ecosystem models (e.g., Chesapeake Bay) are 

 sufficiently developed to allow semi-quantita- 

 tive predictions about cause-effect relationships 

 between some biologic components (e.g., 

 plankton) and abiotic conditions. Other biolog- 

 ical components need to be added to the model- 

 ing framework, especially as related to food 

 web interactions. Future status and trends 

 information gathering should be supportive of 

 ecosystem model development wherever possi- 

 ble. 



References 



Bartscti. A.F.. and W.M. Ingram. 19.'i9. Stream life and the 

 pollution environment. Public Works 90:104-1 10. 



Chmielewski. CM., and R.J. Hall. 1993. Changes in the 

 emergence of blackflies (Diptera: Simuliidae) over 50 

 years from Algonquin Park streams: is acidification the 

 cause' Canadian Journal of Fisheries and Aquatic 

 Sciences 50:1517-1529. 



Messer, J.J., R.A. Linthurst, and W.S. Overton. 1991. An 

 EPA program for monitoring ecological status and 

 trends. Environmental Monitoring and Assessment 

 17:67-78. 



