Major Emergent Patterns in the Matrix

The first emergent point is that the manifold of human interactions with freshwater habitats can have positive and negative effects. Second, clines in extent and severity of these impacts span across the table, from incidental recreative visits to a lake in sparsely inhabited boreal zones, via subsistence fisheries and littoral reed harvesting to depletive fisheries and wholesale reclamation. Thus, a simple question on the effect of recreation and navigation in inland waters will require further specification. The presented matrix is only a broad-brushed effort to do so.

The prime service of inland waters to human society worldwide is the provision of clean fresh water. This too has been recognized early in human history, as witnessed by the impressive waterworks still remaining from ancient cultures. High density lakeside development and intensive navigation are both a consequence of increased population density, economic development and affluence. Both may severely affect this ecosystem service in the competitive struggle for water as a resource and a geographic feature. A range of other services (i.e., flood control and storm buffering, water supply, water quality improvement, habitat and nursery for commercial interesting species, recreational hunting and fishing, raw materials, amenity and biodiversity) has been identified for wetlands and inland waters alike. The overall economic value connected to these services is still the subject of methodological and conceptual study and debate. Generally, these values were found to be a positive function of national GDP and population density, and covary negatively with total wetland area. Hence in more affluent societies, these services are valued higher, although the remaining area of unaffected habitat is declining and remaining fragments have received a protection status.

w to

Table 1 Breakdown of the effects of human use in four different categories of inland water bodies

Type of human use

Larger lakes

Wetlands,

Rivers

Artificial

Explanatory remarks

and lake

marshes,

and

water

districts

and ponds

streams

ways

1. Recreative trekking, canoeing

0

0

0

0

Low intensity recreation is generally not considered to have negative effects (1)

and swimming

2. Recreative hunting and

-/0

-/0

-/0

-/0

Recreative fishing may alter the composition of fish stocks and can be accompanied by

fishing

artificial stocking with target species

3. Recreative sailing and

-/0

-/0

-/0

-/0

Littoral fringes, reed beds and submerged vegetation may be affected by intense boat traffic

boating

(2-5)

4. Commercial and subsistence

-/0

-/0

-/0

-/0

Commercial fisheries as well as trapping and hunting have greatly altered densities of target

vertebrate species (6, 7)

fisheries, trapping, and hunting

5. Planned or unplanned food-web manipulation; introduction of new species, biological invasions

6. Exploitation of other natural resources

7. Commercial shipping

8. Shoreline development with cottages, mooring piers, and boat houses

9. Permanent settlement: trading posts, villages, and towns

10. Irrigation and drainage, flow diversion, flow regulation, damming for hydropower or navigation

vertebrate species (6, 7)

-/0 -/0 -/0/+ Fish stock manipulation may be considered positive and negative. Released large herbivores

(e.g., muskrat) may affect wetland vegetation. Altered balances of planktivorous and piscivorous fish will affect zoo- and phytoplankton. Classical examples: the nile perch in Lake Victoria for introduction of nonnative fish and filtering zebra mussels into the North American Great Lakes as unplanned biological invasion. (6, 8-10) -/0/+ -/0/+ 0/+ Managed exploitation may have beneficial effects on biodiversity of semi-natural wetlands, such as reed-cutting to maintain reed bed flora and fauna. Exploitation of sand and gravel in unregulated river beds is an alteration of habitat and may affect spawning grounds of fish. Regular dredging and clearing of ditches maintains the aquatic habitat (11)

- - -/0 Enhanced shipping intensity may increase biological invasions; the North American Great

Lakes and the Danube-Rhine canal are examples. Artificial waterways may serve in connecting previously isolated lake systems. Otherwise see 3 above (12-14)

- -/0 0/+ With growing affluence, recreative settlements develop along lake shores. These generally affect littoral wetland vegetation first, but all littoral habitats follow suit and fish communities change (15, 16)

- - -/0/+ The consequence of economic development of society along rivers and other navigation networks. Effects generally aggravate those mentioned under 8. Deposition of human solid waste and disposal of domestic and industrial sewage are a consequence of the development of human settlements. Since these water bodies are created by man's activities, urban settlement is a primary cause of their existence, and hence should be judged positively when judged in isolation

- - + Upstream irrigation schemes may cause massive degradation in downstream lakes, wetlands and rivers. Classical examples are the drying-up of the Aral Sea and the reduction of freshwater flows and sediments to coastal wetlands and mangroves (14, 17-21). Flood regulation along river corridors will affect habitat prevalence and cause reduced biodiversity (22-24). Otherwise, like the previous entry, human activity is the root cause of the mere existence of these water bodies, and hence positive a>

11. Reclamation

Reclamation of wetlands generally involves the creation of artificial waterways such as drainage ditches as new aquatic habitat, but overall the balance is negative (20, 21, 25)

Key references are given in parentheses. Effects are judged negative, neutral, or positive (—, 0, +). Often, two or even three options are possible; the most probable is given in bold. The perspective is the provision of services to human society, including their mere existence.

Sources

1. Vermaat JE, Goosen H, and Omtzigt N (2007) A multivariate analysis of biodiversity patterns in Dutch wetland marsh areas: Urbanisation, eutrophication or fragmentation? Biodiversity Conservation 16: 3585-3595.

2. Mosisch TD and Arthington AH (1998) The impacts of power boating and water skiing on lakes and reservoirs. Lakes Reservoir Research Management 3: 1-17.

3. Hilton J and Phillips GL (1982) The effect of boat activity on turbidity in a shallow Broadland river. Journal of Applied Ecology 19: 143-150.

4. Vermaat JE and De Bruyne RJ (1993) Factors limiting the distribution of submerged waterplants in the lowland river Vecht (The Netherlands). Freshwater Biology 30: 147-157.

5. Murphy KJ and Eaton JW (1983) Effects of pleasure boat traffic on macrophyte growth in canals. Journal of Applied Ecology 20: 713-729.

6. Balirwa JS, Chapman CA, Chapman LJ, et al. (2003) Biodiversity and fishery sustainability in the Lake Victoria Basin: An unexpected marriage? Bioscience 53: 703-715.

7. Coble DW, Bruesewitz RE, Fratt TW, et al. (1990) Lake trout, sea lampreys, and overfishing in the upper Great Lakes: a review and reanalysis. Transactions American Fisheries Society 119: 985-995.

8. Andersson G, Berggren H, Cronberg G, et al. (1978) Effects of planktivorous and benthivorous fish on organisms and water chemistry in eutrophic lakes. Hydrobiologia 59: 9-15.

9. Danell K (1979) Reduction of aquatic vegetation following the colonization of a Northern Swedish lake by the muskrat, Ondatra zibethica. Oecologia 38: 101-106.

10. Witte F, Msuku BS, Wanink JH, et al. (2000) Recovery of cichlid species in Lake Victoria: An examination of factors leading to differential extinction. Reviews in Fish Biology and Fisheries 10: 233-241.

11. Guesewell S and Le Nedic C (2004) Effects of winter mowing on vegetation succession in a lakeshore fen. Applied Vegetation Science 7: 41-48.

12. Gutreuter S, Vallazza JM, and Knights BC (2006) Persistent disturbance by commercial navigation alters the relative abundance of channel-dwelling fishes in a large river. Canadian Journal of Fisheries and Aquatic Sciences 63: 2418-2433.

13. Lodge DM, Williams S, Macisaac HJ, et al. (2006) Biological invasions: recommendations for U.S. policy and management. Ecological Applications 16: 2035-2054.

14. Nentwig W (ed.) (2007) Biological Invasions. Ecological Studies, vol. 193. Springer.

15. Scheuerell MD and Schindler DE (2004) Changes in the spatial distribution of fishes in lakes along a residential development gradient. Ecosystems 7: 98-106.

16. Brazner JC (1997) Regional, habitat, and human development influences on coastal wetland and beach fish assemblages in Green Bay, Lake Michigan. Journal of Great Lakes Research 23: 36-51.

17. Aladin NV and Potts TW (1992) Changes in the Aral Sea ecosystems during the period 1960-1990. Hydrobiologia 237: 67-79.

18. De Groot SJ (2002) A review of the past and present status of anadromous fish species in the Netherlands: Is restocking the Rhine feasible? Hydrobiologia 478: 205-218.

19. Thampanya U, Vermaat JE, Sinsakul S, et al. (2006) Coastal erosion and mangrove progradation of Southern Thailand. Estuarine and Coastal Shelf Science 68: 75-85.

20. Brinson MM and Malvarez AI (2002) Temperate freshwater wetlands: types, status, and threats. Environmental Conservation 29: 115-133.

21. Tamisier A and Grillas P (2003) A review of habitat changes in the camargue: An assessment of the effects of the loss of biological diversity on the wintering waterfowl community. Biological Conservation 70: 39-47.

22. Pollock MM, Naiman RJ, and Hanley TA (1998) Plant species richness in riparian wetlands—A test of biodiversity theory. Ecology 79: 94-105.

23. Girel J and Manneville O (1998) Present species richness of plant communities in alpine stream corridors in relation to historical river management. Biological Conservation 85: 21-33.

24. Sabo JL, Sponseller R, Dixon M, et al. (2005) Riparian zones increase regional species richness by harboring different, not more, species. Ecology 86: 56-62.

25. Van Turnhout CAM, Foppen RPB, Leuven RSEW, et al. (2007) Scale-dependent homogenization: Changes in breeding bird diversity in the Netherlands over a 25-year period. Biological Conservation 134: 505-516.

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