The contribution of man-made ditches to the regional stream biodiversity of the new river watershed in the Florida panhandle

Abstract

The role of ditches as reservoirs for or contributors to regional diversity has rarely been assessed. In this study, we aimed (1) to assess the effect of ditches on aquatic faunal assemblages of first order streams and (2) to assess the extent to which the animal communities in altered streams that are crossed by ditches resembled those found in nearby natural streams. We examined the fauna of four different aquatic habitats of the New River watershed in the Florida Panhandle: (1) natural streams, (2) altered streams, (3) ditches that cross the altered streams, and (4) ditches that do not cross the altered streams, sampling these habitats in three geographically distinct sites and visiting each location three times during a summer. Ditches did not have the same environmental features as streams and as a result their faunal community did not completely mimic those of natural streams. Streams contained 50% less aquatic vegetation and more canopy cover, while natural streams were more acidic than any other habitat. The connected altered stream and ditch habitats contained the highest biodiversity, while natural streams contained the lowest. Our ordination of taxonomic composition did not reveal any significant differences between habitats. However, natural streams were more likely to contain Hyalella spp., Oligochaetes, and Palaemonetes spp. than other sites, yet did not contain Baetidae spp., Naucorida spp., Trepobate spp., Dolomedes okefinokensis, Leptolucania ommata, or any Centrarcids. These results indicate the importance of ditches within this system as a reservoir for and contributor to regional stream biodiversity and this finding should be taken into consideration by managers for the conservation of the regional freshwater biodiversity.

Managing ditches for agroecological engineering of landscape. A review

“…Wetland plants in ditches are most likely residual marsh plant species that were present before the area has been drained (Herzon and Helenius 2008). Furthermore, in drainage ditches that are characterized by a rather perennial base flow, the invertebrate diversity has been reported to be higher than in small lakes and streams (Simon and Travis 2011;Verdonschot et al 2011;Williams et al 2004). The number of bird species can also double if ditches are present in cropped areas (Arnold 1983;Herzon and Helenius 2008;Marja and Herzon 2012).…”

“…The ditch ecosystem, including beds, sidewalls, and margins, provides a stratification of microhabitats ranging from aquatic to wetland and terrestrial types (Marja and Herzon 2012). This stratification of habitat type depends on the vegetation cover (permanence and type) and on the water level fluctuations (Bellavance and Brisson 2010;Simon and Travis 2011;Twisk et al 2003;Verdonschot et al 2011;Williams et al 2004).…”

An Irrigation Canal as a Lotic Mesocosm: Examining the Relationship between Macroinvertebrate Benthos and Drift

“…In the United States, canals have been understudied and their effects on aquatic and terrestrial organisms and nonagriculture services (e.g., uptake/release of nutrients, decomposition of organic matter) are largely unknown (Herzon and Helenius 2008, Roach et al 2008, Simon and Travis 2011. In addition, irrigation canals have become a dominant aquatic feature in the arid West and now provide new habitat and increased habitat heterogeneity for fish (Mueller andListon 1994, Cowley et al 2007) and invertebrates (Marsh andStinemetz 1983, Simon andTravis 2011).…”

“…Some canals can resemble small stream ecosystems, complete with sand/pebble/cobble substrate, small pools, and riparian/emergent vegetation (Herzon and Helenius 2008). Ditches can provide habitat for aquatic invertebrates not found in larger, perennial bodies of water (Williams et al 2004) and may increase taxonomic invertebrate richness in stream networks by increasing habitat heterogeneity (Simon and Travis 2011).…”

“…These systems may resemble small natural streams (Simon andTravis 2011, Leslie et al 2012); they are accessible and easily sampled, may have fairly low species richness (usually species prone to drift), and have stable and constant discharge throughout the irrigation season. Their "fill history" is obtainable either from irrigation districts or by direct observation.…”