Aquatic Invertebrate Survey at Greylake RSPB Reserve, Somerset

Aquatic invertebrate survey at Greylake RSPB Reserve, Somerset

C. Martin Drake 2008

Dr C. M. Drake Orchid House Burridge Axminster Devon EX13 7DF

Summary In July 2008, 35 pond-net samples were taken from old and new ditches, new gutters and new ponds on RSPB’s Greylake Reserve. A total of 137 aquatic species and 47 wetland insects were found, of which 60 species were water beetles 20 were molluscs and 14 were bugs. There were 25 nationally scarce and three Red Data Book species (including beetles that are likely to be given lower status in future).

There were pronounced differences in the assemblages of the found in the various types of channel, with notably more beetles in new channels and more molluscs and leeches in old ditches. New ditches and gutters were as rich in all species and had similarly high Species Quality Index to old ditches. Blind and connected gutters appeared to support slightly different assemblages but there was no discernible difference in the species-richness of the major groups or in SQI. Ponds were usually the poorest water bodies in all respects but their fauna was also more variable than that of channels.

Comparison of results of a recent survey of molluscs suggests that this group is slowly increasing in importance within the reserve, probably as a result of benign management.

The diversity of new water bodies clearly increased the range of species and gave many more opportunities for species with clear preferences for different water depths and vegetation structure.

Introduction A narrow block of arable and improved grassland at Greylake was bought by the RSPB who began work in 2003 on improving the site to benefit breeding waders. The site links old pasture of Moorlinch SSSI and Kings Sedgemoor SSSI to form a large continuous block with high conservation interest. Twenty square 5 hectare fields are divided by old ditches managed by the RSPB. Boundary ditches are managed by the Environment Agency and IDB. Between 2003 and 2007, RSPB dug a variety of channels which include new ditches deep enough to remain permanently wet, and shallow gutters that dry out in late summer. The gutters are either connected to permanent ditches or isolated. There are also new pools varying in size and connectivity to ditches.

The site was surveyed principally for aquatic molluscs in October 2003 and September 2004 before the new ditches and pools had become established (Hill-Cottingham & Smith, 2004). Several rare and scarce species were found then, including the RDB2 snail Valvata macrostoma in the boundary ditches, the soldierfly Odontomyia ornata, and the beetles Hydaticus transversalis and Hydrophilus piceus (Great Silver water beetle).

The present survey was designed to give a broader baseline for future monitoring. This will enable the development of invertebrate fauna in response to management of the site, including the proposal to link the site to flood events in the neighbouring floodplain, to be tracked. This survey also aims to indicate the conservation value of the different types of new channels and pools.

Methods Samples were collected using the protocol developed by Buglife for grazing marsh ditches (Palmer et al., 2007). The sample is taken using a standard pond-net with 35cm-deep bag and the animals are sorted on the bank on a polythene sheet. Each sample consists of four net-hauls, each of which is sorted for 7.5minutes so that the effort is a standard ½ hour search. Netting is done to catch as much as possible, and is not standardised in any way. Most effort is spent in densely vegetated shallow water and least in open water as experience had shown that this is how most species can be found. Very shallow water and saturated soil with no visible water were sampled by gently trampling to form a pool that could be netted.

Species that could be confidently identified in the field were noted on a form. Others were preserved in alcohol. Abundance of recognisable taxa was estimated on the logarithmic scale 1- 9, 10-99, ≥100.

Environmental variables were collected following the Buglife ditch protocol and form (Appendix 3); results for selected variables are given in Appendix 5. Each sampling point was photographed.

The following types of channel were sampled:

Field Established New ditch Connected Blind Pond (‘Old’) ditch gutter gutter 2 + 3 + + 5 + + ++ 6 + + + + 7 + 9 + + + 10 + + 11 + + + + 12 + + + 13 + + + 16 + + + + 17 + + 20 + + Total 10 10 5 5 5

The channels were chosen to ensure a spread across the reserve but different types were chosen from the same field where possible so that variation due to grazing management was reduced. Thus 25 of the 35 samples came from just seven fields (Figure 1). New channels varied in age and some had been cleaned since they were dug so, to reduce variation due to these influences, the selection included only the older ‘new’ ditches and gutters dug in 2003 or 2004 and, with the exception of one gutter, none that had been cleaned since dug. Samples were taken close to water sampling points in three old ditches and one new ditch in fields 5, 6 and 20. No samples were taken from the boundary ditches. The position of gutters in Figure 1 is indicated since it was sometimes difficult to be sure which was which in the tall vegetation in midsummer, and

2 there was slight discrepancy between the base map or ditches that were marked as cleaned and the actual position of gutters in fields 3, 12 and 13. The position of symbols in Figure 1 is the actual sampling point. Appendix 1 gives the grid reference of each sampling point.

Sampling took place on five days between 17 and 23 July 2008. While midsummer may not be the ideal time for ditch sampling, it was decided that the survey would be better done earlier than later in the season in case the gutters dried out.

Most macro-invertebrate groups were identified to species, and only groups that could be identified to species level were collected since no useful information about conservation status of sites can be gleaned from higher taxa. Flatworms, most fly larvae and mites were therefore ignored. Pea mussels (Pisidium) were not identified to species. Dragonfly larvae were taken as far as practicable but current keys do not reliably separate some species that may have been present. Some wetland species not included in the traditionally recognised ‘aquatic’ groups were collected, such as leaf beetles (Chrysomelidae), some rove beetles (Staphylinidae) and marsh beetles (Scirtidae).

The numbers of each species were counted. Estimates of abundance made in the field for taxa that were not collected in large numbers (e.g. hoglice) were converted to the numerical values 2, 20 and 110 for the purpose of ordination.

Figure 1. Sampling points at Greylake Reserve. O – old ditch, N – new ditch, G – gutter, P – pond. The position of gutters is marked by a black line to avoid confusion on the ground.

Analysis Non-parametric statistics were used when analysing the results since the sample points were not randomly selected. Medians were compared using the Kruskall-Wallis statistic. DCA and CCA ordinations were done on abundance data with downweighting of species that were scarce in the dataset, using software by Pisces (2002, 2004). Species Quality Score was calculated for all aquatic grazing marsh species listed in Palmer et al. (2007); this excludes wetland species such as donacine reed beetles. The individual scores allocated to each species are shown with the raw data in Appendix 4. Rarity statuses are those used in Recorder 3 (DOS version) and in the JNCC website of species of conservation concern (definitions given in Appendix 2). Proposed IUCN statuses are those of Foster (in prep.) which have been in circulation for many years but not formally published.

Taxa such as immature individuals or females that could not be identified to species were included in counts of species and in ordination only if they did not duplicate species-level identifications.

Results Species richness A total of 184 species of invertebrates was recorded, of which 137 were conventionally recognised aquatic species and the other 47 were wetland insects (Appendix 4). Both freshwater sticklebacks were frequent, and smooth newt (Triturus vulgaris) was also recorded. Water beetles formed the most speciose group (60 species), followed by molluscs (20 species) and bugs (14 species).

Nationally rare and scarce species were well represented (Table 1). There were 25 scarce species, including four wetland beetles not in the usually recognised water beetle families, and three Red Data Book species (or provisionally RDB). These are the old JNCC statuses, and seven or eight of the beetles are likely to be given a lower status using the IUCN statues (Foster, in prep.). Those thought to be no longer of conservation concern are Hydroglyphus pusillus, Rhantus suturalis, Helophorus griseus, Anacaena bipustulata, Cercyon convexiusculus, Cercyon tristis and Helochares lividus which all occur in more than 100 hectads (the threshold for inclusion as nationally scarce). The single specimen of the tiny beetle Chaetarthria was a female which cannot be identified to species, but the commoner of the two British species is scarce.

Some of the nationally rare or scarce species were clearly frequent at Greylake, including the three rarest species, the Great Silver water beetle (Hydrophilus piceus), the diving beetle Hydaticus transversalis and the large soldierfly Odontomyia ornata. These are ‘flagship’ species of grazing marsh where they are common, but are scarce in other habitats. Scarce species, other than those due for downgrading, that were particularly frequent at Greylake were the diving beetles Hydaticus seminiger and Rhantus grapii, the crawling water beetle Limnoxenus niger and the soldierfly Odontomyia tigrina; these are all moderately large species. The records of Hydaticus seminiger are probably the most interesting as this beetle has been infrequently recorded in Somerset before (Foster, 1985).

The scarce wetland species included the semi-aquatic ground beetle Oodes helopioides which spends much time submerged, the ground beetle Odacantha melanura associated with reeds and water margins, the jumping marsh beetle Scirtes orbiculare which has aquatic larvae, and the large cranefly Phalacrocera replicata whose aquatic larvae eat mosses.

Table 1. Rare and scarce species in each type of channel at Greylake. † - wetland beetles not included as ‘water’ beetles * - proposed IUCN status is ‘Lower Risk, least concern’

Order, Family Species Status Type of channel Total gutter ditch pond blind connected connected new old cleaned COLEOPTERA Carabidae† Odacantha melanura Nb 0 0 0 0 1 0 1 Oodes helopioides Nb 0 1 0 0 0 0 1 Dytiscidae Hydaticus seminiger Nb 5 1 0 3 2 1 12 Hydaticus transversalis pRDB3 3 4 0 2 7 1 17 Hydroglyphus pusillus Nb* 0 0 0 0 0 1 1 Hygrotus parallelogrammus Nb 2 1 0 0 0 0 3 Rhantus frontalis Nb 0 0 0 1 1 0 2 Rhantus grapii Nb 3 0 0 4 5 0 12 Rhantus suturalis Nb* 5 4 0 7 6 2 24 Haliplidae Peltodytes caesus Nb 0 0 1 2 4 0 7 Helophoridae Helophorus griseus Nb* 0 0 0 0 0 1 1 Hydrophilidae Anacaena bipustulata Nb* 0 0 0 0 5 0 5 Berosus affinis Nb 0 0 0 0 0 1 1 Cercyon convexiusculus Nb* 0 0 0 0 1 0 1 Cercyon sternalis Nb 0 2 0 1 0 0 3 Cercyon tristis Nb* 4 3 0 5 3 1 16 Chaetarthria (female) Nb 0 0 0 0 1 0 1 Enochrus ochropterus Nb 0 1 0 1 0 0 2 Helochares lividus Nb* 2 1 0 4 3 0 10 Hydrophilus piceus RDB3 1 3 0 8 8 2 22 Limnoxenus niger Nb 3 2 1 5 3 2 16 Scirtidae† Scirtes orbicularis Na 0 0 0 2 6 2 10 Staphylinidae† Stenus fornicatus Nb 0 0 0 3 4 3 10 DIPTERA Cylindrotomidae Phalacrocera replicata Nb 0 0 0 1 0 0 1 Stratiomyidae Odontomyia ornata RDB2 4 4 0 10 7 4 29 Odontomyia tigrina Nb 3 4 0 7 1 2 17 Stratiomys singularior Nb 1 2 0 2 0 0 5 ODONATA Aeshnidae Brachytron pratense Nb 0 0 0 1 0 0 1 total species 12 14 2 19 18 13

Two non-native species were widespread. The freshwater shrimp Crangonyx pseudogracilis is a common species of still water; it was in nearly every channel and pond at Greylake although abundant in only two places. It is now ubiquitous in grazing marshes in Somerset but was far less common in 1983 when the first large survey was undertaken (Drake et al., 1984). The snail Physella ?acuta was also widespread at Greylake. It was present in every channel type, showed no obvious preference, was in 22 of the 35 samples and was often frequent and sometimes numerous. Hill-Cottingham & Smith also found it widely at Greylake in 2003-4 but it was not recorded in the 1983 Somerset Levels survey. The fauna of different channel types DCA ordination showed that different assemblages were associated with each channel type (Figure 2). Eigenvalues for axes 1 and 2 were moderately large (0.347 and 0.237, respectively) which suggested that there were real differences between assemblages on both these axes. Old ditches clustered well together and were separated from new ditches. Assemblages of gutters were more variable and overlapped with those of new ditches although clearly separated from those of old ditches. Some blind gutters did appear to be different from connected gutters. Pond assemblages were also variable but most showed greater similarity with those of ditches than of gutters. The single sample from a recently cleaned gutter was a distinct outlier that showed no similarity with any other ditch type.

250

200

150

100 Axis 2 Axis scores blind gutter connected gutter cleaned gutter 50 new ditch o ld ditch po nd 0 0 50 100 150 200 250 300 Axis 1 scores

Figure 2. DCA of all aquatic species in different channel types at Greylake.

A number of environmental variables were significantly correlated with the scores for either axis 1 or axis 2, using Spearman’s rank correlation statistic (Table 2). These indicated that the assemblages were influenced by: - physical structure of the channels influenced the assemblages (ditch profile under the water, water depth, open water surface) - vegetation structure (submerged plants, grassy margin, floating duckweeds and other plants and the amount of emergents in the channel) - chemistry (pH and conductivity)

Several of these variables are related to one another, for instance, well grazed fields led to better developed grassy margins and less tall herb, and wider deeper ditches tended to have more submerged plants and more open water. These relationships are illustrated in a CCA plot that included just these apparently key variables (Figure 3). As the ordination constrained by the variables will arrange the samples differently, depending on which variables are included, the distribution of samples only superficially resembles that of the DCA plot (Figure 4). For example, the outlying old ditch point in the CCA plot was from the inflow ditch with had several species restricted to flowing water, and which had a stronger influence on the CCA scores than on the DCA scores. However, both ordinations show that old and new ditches tend to separate from gutters, and the direction and strength of the CCA vectors tend to confirm the rank correlation analysis of DCA scores with variables. Table 2. Significant Spearman’s rank correlation rs statistic of the first two DCA axes with environmental variables, in order of the 2-tailed probability of it occurring by chance. Variable rs p Axis 1 Submerged plants 0.58 0.0003 Conductivity 0.53 0.001 Open water surface 0.53 0.001 Emergents/floating mat in channel -0.43 0.0105 Tall herbs 0.39 0.0223 Profile under water 0.37 0.0271 Grassy margin -0.36 0.0344 pH 0.34 0.0476 grazed -0.34 0.049 Axis 2 Profile under water -0.56 0.0004 Conductivity -0.55 0.0005 Shelf formation -0.49 0.0027 pH -0.48 0.0037 Scrub -0.46 0.0055 Water depth -0.4 0.0162 Emergents/floating mat in channel 0.4 0.0168 Water width -0.4 0.0169 Floating Lemna/Azolla -0.39 0.0189 Other floating aquatics -0.39 0.0223 Submerged plants -0.38 0.0232

Figure 3. CCA vectors for selected environmental variables.

0 -2 -1 0 1 2 3 4 5 6

-1 Axis 2 scores

blind gutter

-2 connected gutter cleaned gutter new ditch

-3 old ditch pond

-4 Axis 1 scores

Figure 4. CCA plot of samples, corresponding to the vectors in Figure 3.

Total species richness did not differ greatly between the different types of channel, although pond was among the least species-rich (Figure 5). The single sample of a cleaned gutter, which was devoid of vegetation, supported particularly few species. Although total species-richness did not vary widely between the types of channel, there were some marked differences in the species richness of the three main invertebrate groups. Beetles were more speciose in gutters and new ditches, slightly less so in old ditches, and notably species-poor in ponds. Bugs showed the opposite trend, with fewer species in many gutters and more in ditches and ponds. Molluscs were mostly poor in all channels except old ditches which were clearly far richer than any other channel type.

Species Quality Score differed slightly between channel types (Figure 6). When the single cleaned gutter sample was removed, the difference between the five types was significant (Kruskall-Wallis statistic = 11.05, p>0.05). The range of values in Figure 4 suggests that gutters (except for the recently cleaned one) had a greater SQI than the ditches and ponds.

The difference between new channels (gutters and ditches) and old ditches was marked for some species (Table 3). In general, water beetles preferred the new ditches, and molluscs and leeches preferred the old ditches.

A few of the rare or scarce species appeared to show preferences for certain channel types although the number of occurrences were small, so some variation is likely to be due to chance (Table 1). Peltodytes caesus and the wetland beetles Scirtes orbicularis and Stenus fornicatus clearly favoured new and old ditches, and Hydrophilus piceus, Rhantus grapii and Odontomyia ornata showed a similar tendency. The soldierfly Odontomyia tigrina was slightly more frequent in the any newer type of channel compared to old ditches and ponds. Hydaticus seminiger and Cercyon tristis favoured gutters.

Table 3. Species showing preferences for new channels (gutters and new ditches) or old ditches.

Species Family Status gutter new old pond ditch ditch Number of samples 10 10 10 5 Preference for gutters and new ditches Agabus bipustulatus Col., Dytiscidae common 9 8 5 3 Colymbetes fuscus Col., Dytiscidae common 6 6 1 1 Hydaticus seminiger Col., Dytiscidae scarce 6 3 2 1 Hydroporus planus Col., Dytiscidae common 7 8 2 3 Ilybius ater Col., Dytiscidae common 4 2 0 1 Rhantus suturalis Col., Dytiscidae scarce 9 7 6 2 Helophorus brevipalpis Col., Helophoridae common 9 9 2 3 Helophorus minutus Col., Helophoridae common 8 8 4 3 Ochthebius minimus Col., Hydraenidae common 5 3 0 1 Cercyon marinus Col., Hydrophilidae local 9 7 1 2 Cercyon tristis Col., Hydrophilidae scarce 7 5 3 1 Cymbiodyta marginellus Col., Hydrophilidae local 4 2 0 1 Limnoxenus niger Col., Hydrophilidae scarce 6 5 3 2 Dixella autumnalis Dipt., Dixidae local 7 8 3 1 Odontomyia ornata Dipt., Stratiomyidae RDB2 8 10 7 4 Odontomyia tigrina Dipt., Stratiomyidae scarce 7 7 1 2 Stratiomys singularior Dipt., Stratiomyidae scarce 3 2 0 0 Preference for old ditches Tanysphyrus lemnae Col., Curculionidae local 3 5 8 3 Hyphydrus ovatus Col., Dytiscidae common 0 0 8 0 Scirtes orbicularis Col., Scirtidae scarce 0 2 6 2 Bithynia tentaculata Moll., Bithyniidae common 0 0 4 0 Lymnaea palustris Moll., Lymnaeidae common 4 5 8 2 Lymnaea stagnalis Moll., Lymnaeidae common 1 5 9 3 Anisus vortex Moll., Planorbidae common 3 4 10 2 Planorbis planorbis Moll., Planorbidae common 2 3 7 2 Musculinum lacustre Moll., Sphaeriidae common 0 1 5 0 Sphaerium corneum Moll., Sphaeriidae common 0 1 5 0 Sialis lutaria Megaloptera, Sialidae common 1 1 4 2 Ischnura elegans Odonata, Coenagriidae common 2 5 9 0 Erpobdella octoculata Hirudinea, Erpobdellidae common 0 3 7 2 Theromyzon tessulatum Hirudinea, Glossiphoniidae common 3 4 10 5

All Taxa Coleoptera

70 35

60 30

50 25

40 20

30 15

Numbertaxaof Numberspeciesof 20 10

10 5

0 0

pond

oldditch

newditch

blindgutter

cleanedgutter

connectedgutter connectedgutter

Hemiptera Mollusca

10 14

12 8 10

6 8

Numberspeciesof Numberspeciesof 4 2 2

0 0

pond

oldditch

newditch

blindgutter

cleanedgutter

connectedgutter connectedgutter

Figure 5. Median with upper and lower quartiles for all taxa and the three main groups in each channel type. Cleaned gutter was represented by just one sample and the top of its column is the median value.

SQI 3

2 SQI

pond

old ditch

new ditch

blind gutter

cleaned gutter connected gutter

Figure 6. Median Species Quality Score with upper and lower quartiles in each channel type.

Discussion Greylake supports a good fauna typical of Somerset grazing marsh with permanent pasture. The total of 60 species of water beetles exceeds the suggested threshold for a candidate site for SSSI notification (Nature Conservancy Council, 1989). The complement of scarce and rare species is as expected from the SSSIs in the Somerset Levels, and several of them are clearly thriving in both the recently created channels as well as in the old ditches. Despite their recent age, the new channels were as well populated with scarce and rare species as the older ones, and these species were as well represented in the shallow gutters as in older or deeper ditches. Ponds tended to be the least interesting water bodies.

There was a marked change in the assemblage occupying the shallow gutters and old ditches, with the new permanent ditches falling between these two extremes. Ponds were less clearly defined as an entity. Factors influencing the assemblages were related to the physical and vegetation structure, with some influences almost certainly due to effect of cattle trampling and grazing and unexpectedly to pH and conductivity. Shallow, densely vegetated gutters and new ditches were dominated by water beetles which were sometimes exceedingly abundant, whereas snails and leeches were notably scarce here. Older ditches supported far smaller numbers of beetles, but the more open character suited bugs and damselflies instead. The diversity of channels therefore contributed markedly to the interest of the site as a whole.

There were indications that several molluscs were moving into the site. Hill-Cottingham & Smith (2004) recorded relatively few molluscs species in the old ditches, comparable to the numbers found in new ditches and lower than in old ditches in the present survey. However, they found more species in the boundary ditches (not sampled in 2008) where several common species were either confined or most frequent (Bithynia leachii, B. tentaculata, Gyraulus albus, Lymnaea stagnalis, Valvata piscinalis and Sphaerium corneum. The scarcity or absence of these normally widespread species within the reserve ditches in 2003-4 is noteworthy, but all were found in the present survey in the internal old ditches, albeit rarely except for L. stagnalis and S. corneum which were now frequent in old ditches, and L. stagnalis also in the new ones. This may not be a spectacular advance, but it does suggest that the disparity between the boundary ditches and ‘internal’ old ditches may be breaking down as a result of more benign management. Slow colonisation of new sites by snails has been previously documented (Hingley, 1979) so a slow start is inevitable.

Acknowledgements

References Drake, C.M., Foster, A. P. & Palmer, M. 1984. A survey of the invertebrates of the Somerset Levels and Moors. Chief Scientist Team Report, Nature Conservancy Council. 354pp.

Foster, G. N. 1985. Atlas of British water beetles preliminary edition – part 4. The Balfour- Browne Club Newsletter No. 35, 1-22.

Foster, G. N. (in prep). A review of the scarce and threatened Coleoptera of Great Britain. Part 3. Aquatic Coleoptera. Joint Nature Conservation Committee, Peterborough.

Hill-Cottingham, P. & Smith, A.G. 2004. A survey of the ditches on Greylake Reserve. Unpublished report to RSPB.

Hingley, M. R. 1979. The colonisation of newly-dredged drainage channels on the Pevensey Levels (East Sussex), with species reference to gastropods. Journal of Conchology 30, 105-122.

Nature Conservancy Council. 1989. Guidelines for selection of biological SSSIs. Nature Conservancy Council, Peterborough.

Palmer, M., Drake, M. & Stewart, N. 2007. A manual for the survey and evaluation of the plant and invertebrate assemblages of ditches. Version 1. Buglife, Peterborough. (available as download from http://www.buglife.org.uk

Pisces Conservation Ltd. 2002. Community Analysis Package v2.1. www.pisces- conservation.com

Pisces Conservation Ltd. 2004. Ecom II. www.pisces-conservation.com

Appendix 1. Grid references of sampling points.

Field Type of ditch Grif ref 2 old ST37853538 3 blind gutter ST38043557 3 old ST37983559 5 connected gutter ST38213538 5 connected gutter (cleaned) ST38233539 5 new ST33263544 5 old ST38223534 6 blind gutter ST38173532 6 new ST38163525 6 old ST38203532 6 pond ST38113530 7 blind gutter ST38483543 9 new ST38673522 9 old ST38693516 9 pond ST38703527 10 new ST38623506 10 pond ST38513505 11 blind gutter ST38943510 11 connected gutter ST38983525 11 new ST38913519 11 old ST39063512 12 blind gutter ST38823499 12 new ST38823503 12 old ST38963495 13 connected gutter ST39073502 13 new ST39183515 13 old ST39283505 16 connected gutter ST39373478 16 new ST39393479 16 old ST39383486 16 pond ST39163477 17 new ST39573486 17 pond ST39723489 20 new ST39603456 20 old ST39873463

Field Code Changed Appendix 2. Invertebrate Status Categories

Red Data Book Category 1. RDB1 - Endangered Species in danger of extinction and whose survival is unlikely if the causal factors continue operating and whose numbers have been reduced to a critical level or whose habitats have dramatically reduced.

Red Data Book Category 2. RDB2 - Vulnerable Species likely to move into the Endangered category in the near future if the causal factors continue operating. Includes species of which most or all of the populations are declining throughout their range and those in vulnerable habitats.

Red Data Book Category 3. RDB3 - Rare Species with small populations that are not at present Endangered or Vulnerable, but are at risk. They are estimated to exist in only fifteen or fewer 10 km squares, and are usually localised within restricted geographical areas or habitats or are thinly scattered over a more extensive range.

Red Data Book Category I. RDBI - Indeterminate Species considered to be Endangered, Vulnerable or Rare, but where there is not enough information to say which of the three categories (RDB1 to 3) is appropriate.

Red Data Book Category K. RDBK - Insufficiently Known Species that are suspected, but not definitely known, to belong to any of the above categories, because of lack of information. They include species recently discovered or recognised in Britain, in poorly recorded or taxonomically difficult or unstable groups, inhabiting inaccessible or infrequently sampled but widespread habitats or of questionable native status.

Provisional Red Data Book pRDB The prefix "p" before any Red Data Book category indicates a provisional grading.

Nationally Scarce (Notable) Category A - Na Species which do not fall within RDB categories but which are uncommon and thought to occur in 30 or fewer 10 km squares of the National Grid or, for less well recorded groups, within seven or fewer Vice Counties.

Nationally Scarce (Notable) Category B - Nb Species which do not fall within RDB categories but which are uncommon and thought to occur in between 31 and 100 10 km squares of the National Grid or, for less well recorded groups, within between eight and twenty Vice Counties.

Nationally Scarce (Notable) Definition. Species which are estimated to occur in 16 to 100 10km squares in Great Britain. The subdividing of this category into Nationally Scarce A and Nationally Scarce B has not been attempted for some species because of either the degree of recording that has been carried out in the group to which the species belongs, or because there is some other reason why it is not sensible to be so exact.

Appendix 3. Field recording form for ditch invertebrate survey (V.2)

Site Ditch no. Recorder Grid ref. Date Photo

ADJACENT LAND USE A B DITCH FEATURES E/N W/S Water width (m) 0 1 2 3 4 Improved grassland Banktop width (m) 0 2½ 5 7½ 10 Semi-improved grassland Freeboard (cm) 0 20 50 100 200 Unimproved grassland Water depth (cm) Silt depth (cm) Arable -1 Swamp or Fen Conductivity (µScm ) Woodland or Carr pH Other Turbidity Clear Opaq Water colour gin lemon wine tea coffee Cattle/Horse grazed Slope bank A 0 15 30 55 70 Sheep grazed Slope bank B 0 15 30 55 70 Hay/Silage Soil type clay alluv peat sand Stockproof boundary Profile under water 10 30 60 90 Temporary fencing

Spoil on bank

VEGETATION None R O F A D

BANK VEGETATION A B COVER

DAFOR E/N W/S Open water

Tall grass/reed surface Short grass Floating Lemna/Azolla Bare ground Other floating aquatics Tall herbs Floating algae Scrub Submerged plants Fen Submerged algae Woodland ground flora Open substrate Shaded (%) Emergent Floating mat MANAGEMENT Exposed vegetated Years since 1 2-3 4-10 >10 Exposed mud last cleared Litter / detritus Shaded Water relative to cm (+ above normal - below) Emergents/floating mat in channel % Cleared to side A B

Benched profile A B

Cleared by Land IDB EA

manager

GRAZING/ VEG Bank A (E/N) Bank B (W/S) D 70-100% STRUCTURE none low med high none low med high A 30-70% Grazing F 10-30% 0 3-10% Poaching Block formation R <3% Shelf formation Tangled Grassy margin

Appendix 4. Raw data Channel types: O – old ditch, N – new ditch, Gb – blind gutter, Gc – connected gutter, Gcc – cleaned connected gutter Values are abundances

Order / Family Species Status SQI Field and channel type 2 3 5 6 7 9 10 11 12 13 16 17 20 O Gb O Gc Gcc N O Gb N O P Gb N O P N P Gb Gc N O Gb N O Gc N O Gc N O P N P N O AQUATIC SPECIES Amphipoda Crangonyx Crangonycitidae pseudogracilis Alien 0 20 1 20 20 2 20 20 20 20 20 2 2 20 2 20 1 110 110 20 2 20 20 2 2 20 20 2 20 20 2 20 20 20 1 Coleoptera Chrysomelidae Donacia marginata Local 1 1 1 1 1 1 Donacia semicuprea Local 1 Donacia vulgaris Local 1 Curculionidae Tanysphyrus lemnae Local 2 2 4 2 5 1 1 3 1 8 2 2 3 3 2 4 4 1 3 Dryopidae Dryops luridus Common 1 1 1 Dytiscidae Agabus bipustulatus Common 1 2 22 1 10 3 2 1 4 20 3 3 2 7 25 13 3 1 3 10 2 1 1 1 2 9 Agabus sturmii Common 1 1 2 1 1 1 Colymbetes fuscus Common 1 2 2 2 2 2 2 1 2 2 2 2 2 2 2 Dytiscus sp. 1 1 2 1 2 1 1 1 Graptodytes pictus Local 2 1 20 Hydaticus seminiger Nb 4 1 1 1 1 1 2 2 1 2 3 1 Hydaticus transversalis pRDB3 8 2 2 2 3 2 2 2 3 2 2 2 2 2 2 3 Hydroglyphus pusillus Nb 2 2 Hydroporus angustatus Common 1 3 6 1 6 1 4 1 1 3 1 3 1 2 1 Hydroporus palustris Common 1 3 6 9 14 1 1 2 1 6 4 1 1 6 2 3 1 1 28 1 1 8 Hydroporus planus Common 1 2 1 6 9 1 2 1 1 4 2 31 2 1 1 6 8 2 1 2 2 Hydroporus pubescens Common 1 1 11 4 1 1 4 1 1 1 1 2 4 3 4 4 1 1 1 Hydroporus striola Local 2 1 1 3 1 1 Hygrotus impressopunctatus Local 2 1 6 2 12 9 7 1 1 1 6 1 5 1 1 2 Hygrotus inaequalis Common 1 2 20 4 7 3 2 5 2 3 14 12 4 5 6 11 6 9 5 4 7 20 4 15 5 7 9 2 3 Hygrotus parallelogrammus Nb 4 1 1 2 Hygrotus versicolor Local 2 20 Hyphydrus ovatus Common 1 2 2 1 3 3 7 1 20 Ilybius ater Common 1 1 1 2 1 1 1 1

Order / Family Species Status SQI Field and channel type 2 3 5 6 7 9 10 11 12 13 16 17 20 O Gb O Gc Gcc N O Gb N O P Gb N O P N P Gb Gc N O Gb N O Gc N O Gc N O P N P N O Liopterus haemorrhoidalis Local 2 1 1 1 Nebrioporus elegans Common 1 1 Rhantus frontalis Nb 4 1 1 Rhantus grapii Nb 4 5 2 1 1 2 3 1 2 1 1 4 1 Rhantus suturalis Nb 2 9 1 4 31 22 5 2 2 9 16 7 1 4 1 2 7 3 14 3 1 1 1 2 2 Gyrinidae Gyrinus marinus Common 1 1 Gyrinus substriatus Common 1 16 3 1 5 2 20 Haliplidae Haliplus fluviatilis Common 1 3 Haliplus immaculatus Local 2 1 Haliplus lineatocollis Common 1 1 Haliplus ruficollis Common 1 4 1 4 4 1 1 3 25 19 1 1 4 5 2 5 6 6 1 3 1 4 3 1 Haliplus sibiricus Local 2 2 1 3 Haliplus sp. female/larva 2 4 6 6 2 1 1 30 9 2 5 2 10 2 7 7 4 6 1 1 2 1 4 1 21 Peltodytes caesus Nb 4 1 1 1 1 1 3 2 Helophoridae Helophorus aequalis Common 1 2 1 2 Helophorus brevipalpis Common 1 1 4 1 4 2 2 1 6 1 2 1 2 1 7 4 2 5 1 1 6 4 2 2 Helophorus grandis Common 1 1 2 1 1 Helophorus griseus Nb 1 1 Helophorus minutus Common 1 2 1 9 110 12 1 21 3 3 6 8 2 1 1 20 1 3 2 5 28 7 1 1 Heterocerus Heteroceridae fenestratus Common 1 Hydraenidae Ochthebius dilatatus Local 2 1 Ochthebius minimus Common 1 1 4 2 9 3 1 2 4 1 Hydrophilidae Anacaena bipustulata Nb 2 1 1 3 1 2 Anacaena limbata Common 1 1 2 1 5 1 6 1 20 1 4 3 1 6 3 4 3 1 Anacaena lutescens Common 1 110 34 8 110 2 50 31 110 110 43 56 110 42 7 11 40 19 110 110 5 20 3 15 13 45 46 14 15 110 11 20 8 2 10 16 Berosus affinis Nb 4 1 Cercyon convexiusculus Nb 2 1 Cercyon marinus Local 2 2 17 6 1 14 2 34 110 1 110 8 2 4 13 12 1 9 8 8 Cercyon sternalis Nb 4 1 1 2 Cercyon tristis Nb 2 1 1 1 1 1 4 5 8 1 1 3 2 6 1 1 8 Chaetarthria (female) Nb 1 1 Coelostoma orbiculare Common 2 2 2 1 3 1 1 1 1 3 3 1 1 Cymbiodyta marginellus Local 2 6 1 2 1 4 1 10 Enochrus coarctatus Local 2 2 2 2 3 1 4 3 1 2 3 1 12 3 4 3 2 4 1 3 4 5 3 7 1 6 1

Order / Family Species Status SQI Field and channel type 2 3 5 6 7 9 10 11 12 13 16 17 20 O Gb O Gc Gcc N O Gb N O P Gb N O P N P Gb Gc N O Gb N O Gc N O Gc N O P N P N O Enochrus ochropterus Nb 4 1 1 Enochrus testaceus Local 2 1 1 13 2 1 3 2 1 1 1 1 1 1 5 1 1 1 1 Helochares lividus Nb 2 1 2 6 4 1 3 1 1 1 2 Hydrobius fuscipes Common 1 6 14 6 110 2 1 18 20 6 8 20 13 14 3 20 11 2 10 3 20 5 20 21 2 4 12 7 Hydrophilus piceus RDB3 8 2 1 1 6 1 1 2 5 1 1 1 1 8 2 1 2 1 2 1 1 1 1 Laccobius bipunctatus Common 1 3 1 Laccobius minutus Local 2 1 1 1 1 3 2 3 3 1 Limnoxenus niger Nb 4 1 2 1 1 3 8 1 2 3 6 1 1 4 3 4 3 Noteridae Noterus clavicornis Local 2 20 20 20 9 1 7 1 4 4 6 11 2 11 7 12 5 20 14 4 2 12 6 7 4 6 15 7 10 11 Scirtidae Cyphon laevipennis Local 3 2 1 6 3 1 7 Scirtes hemisphaericus Local 1 1 2 2 3 1 1 2 1 1 1 1 1 2 1 1 Scirtes orbicularis Na 1 2 2 2 1 1 1 2 1 1 Diptera Chaoboridae Chaoboridae sp. 2 Chaoborus pallidus 2 1 Culicidae Anopheles claviger Common 1 1 1 3 1 7 1 Anopheles sp. 1 1 Culex sp. 3 9 Culiseta annulata Common 2 5 6 Cylindrotomidae Phalacrocera replicata Nb 2 Dixidae Dixella autumnalis Local 1 6 2 1 4 2 1 1 1 1 1 5 2 1 2 1 3 1 6 Ptychopteridae Ptychoptera 1 1 1 1 1 1 1 Stratiomyidae Odontomyia ornata RDB2 16 2 3 3 13 4 4 7 16 2 3 12 3 23 3 17 19 7 11 2 17 5 3 1 2 5 1 13 2 5 Odontomyia tigrina Nb 4 2 2 4 3 3 4 1 3 1 5 2 1 1 8 4 7 1 Oplodontha viridula Local 2 2 2 4 1 1 3 2 1 6 1 Stratiomys singularior Nb 4 1 1 6 1 2 Syrphidae Eristalini 1 Eristalinus sepulchralis Local 1 1 1 Helophilus sp 1 1 Ephemeroptera Baetidae Cloeon dipterum Common 1 1 6 2 1 4 2 1 3 4 2 1 1 20 1 2 Caenidae Caenis robusta Nr 2 1 1 4 1 1 Hemiptera Corixidae Callicorixa praeusta Common 1 5 Corixa punctata Common 1 1 1 1 1 Corixidae sp. 5 1

Order / Family Species Status SQI Field and channel type 2 3 5 6 7 9 10 11 12 13 16 17 20 O Gb O Gc Gcc N O Gb N O P Gb N O P N P Gb Gc N O Gb N O Gc N O Gc N O P N P N O Hesperocorixa linnaei Common 1 1 4 18 5 110 5 3 1 5 1 60 32 1 13 15 22 19 1 10 4 12 22 17 7 3 3 31 2 22 3 2 Hesperocorixa sahlbergi Common 1 6 1 2 2 3 Sigara dorsalis Common 1 1 22 1 4 8 1 1 2 Sigara semistriata Local 2 24 8 4 3 7 2 1 2 2 1 Gerridae Gerris lacustris Common 1 1 8 Gerris odontogaster Common 1 3 1 1 Gerris sp. 2 1 1 1 2 1 1 2 2 2 1 Naucoridae Ilyocoris cimicoides Common 1 2 2 20 2 20 2 2 2 2 2 20 20 2 2 20 2 1 20 1 20 20 20 2 2 2 2 1 20 2 2 2 Nepidae Nepa cinerea Common 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Ranatra linearis Local 2 2 Notonectidae Notonecta glauca Common 1 1 2 2 2 3 2 1 2 1 1 3 1 2 4 4 3 4 1 1 4 4 2 3 Pleidae Plea minutissima Common 1 1 2 20 2 1 1 Veliidae Microvelia reticulata Common 1 2 4 20 2 2 1 1 20 5 2 2 1 20 20 4 3 4 1 2 2 20 2 15 Hirudinea Erpobdellidae Erpobdella octoculata Common 1 2 2 20 2 2 2 2 2 2 1 2 2 Glossiphonia Glossiphoniidae heteroclita Local 2 2 2 Theromyzon tessulatum Common 1 2 2 2 2 2 2 2 2 20 2 2 2 2 1 2 2 1 1 1 2 2 2 Hirudinidae Haemopis sanguisuga Local 2 2 Isopoda Asellidae Asellus aquaticus Common 1 20 110 110 110 2 20 20 16 20 10 20 20 7 110 2 20 110 110 2 6 20 20 20 20 6 20 20 4 20 20 1 16 Lepidoptera Pyralidae “Cataclysta lemnata” Common 1 2 1 1 1 2 1 1 1 1 1 1 2 1 1 2 1 Mollusca Bithyniidae Bithynia leachii Local 2 1 Bithynia tentaculata Common 1 20 2 20 20 Lymnaeidae Galba truncatula 1 1 Lymnaea palustris Common 1 3 1 1 1 2 4 3 1 1 4 2 3 20 1 1 2 1 20 2 Lymnaea stagnalis Common 1 2 2 2 2 2 2 2 2 2 2 20 2 2 2 20 20 20 20 Radix balthica Common 1 1 2 2 20 2 2 2 2 3 1 2 2 1 2 20 20 2 20 20 2 2 1 2 20 110 110 20 110 2 Physidae Physa not fontinalis Alien 0 20 3 20 20 8 1 110 1 110 3 7 6 1 5 20 20 2 3 3 20 20 20 Planorbidae Anisus leucostoma Common 1 9 Anisus vortex Common 1 20 20 2 7 20 20 20 10 20 2 20 1 2 2 20 2 4 4 12 Bathyomphalus contortus Local 2 20 2 20 110 20 20 20 1 4 4 2 1 1 1 1 2 2 1 2 4 3 Gyraulus albus Local 2 12 1

Order / Family Species Status SQI Field and channel type 2 3 5 6 7 9 10 11 12 13 16 17 20 O Gb O Gc Gcc N O Gb N O P Gb N O P N P Gb Gc N O Gb N O Gc N O Gc N O P N P N O Gyraulus crista Common 1 5 1 1 1 6 1 2 1 1 1 2 Hippeutis complanatus Local 2 2 1 1 Planorbarius corneus Common 1 20 2 2 2 2 20 20 2 2 2 2 2 2 2 2 2 2 2 20 Planorbis carinatus Common 1 1 Planorbis planorbis Common 1 110 1 7 3 1 20 20 12 1 1 2 2 20 1 Sphaeriidae Musculinum lacustre Common 1 1 20 1 2 20 1 Pisidium sp. 1 5 1 1 7 1 1 1 20 2 1 1 1 2 Sphaerium corneum Common 1 20 20 2 4 1 3 Succineidae Oxyloma elegans Common 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Succinea putris Common 1 2 2 2 2 2 2 2 Valvatidae Valvata piscinalis Local 2 1 Neuroptera Sialidae Sialis lutaria Common 1 2 1 1 2 2 2 20 2 Odonata Aeshnidae Aeshna cyanea Common 1 3 4 2 2 1 2 3 1 2 3 1 4 1 2 3 2 4 1 Aeshnidae 1 Brachytron pratense Nb 4 2 Coenagriidae Coenagrionidae sp. 1 1 1 Ischnura elegans Common 1 2 5 6 4 10 1 5 7 8 1 2 6 8 2 1 4 Pyrrhosoma nymphula Common 1 1 Libellula Libellulidae quadrimaculata Common 1 5 1 2 Sympetrum striolatum Common 1 1 1 1 1 17 4 6 9 2 4 3 6 2 5 1 1 8 7 4 Trichoptera Leptoceridae Triaenodes bicolor Common 1 1 1 1 1 1 3 1 1 1 Limnephilidae Limnephilus sp (case) 1 1 1 1 1 1 1 1 1 Phryganeidae Phryganea sp. 1 WETLAND AND TERRESTRIAL SPECIES Coleoptera Carabidae Agonum piceum Local 1 Odacantha melanura Nb 1 Oodes helopioides Nb 1 Pterostichus nigrita Common 1 1 Stenolophus mixtus Local 1 Chrysomelidae Altica lythri Common 5 Galerucella Local 1 1 22

Order / Family Species Status SQI Field and channel type 2 3 5 6 7 9 10 11 12 13 16 17 20 O Gb O Gc Gcc N O Gb N O P Gb N O P N P Gb Gc N O Gb N O Gc N O Gc N O P N P N O nymphaeae

Gastrophysa viridula Common 1 Hydrothassa marginella Common 2 3 1 3 1 1 2 2 1 3 1 2 1 1 Phaedon cochleariae Common 2 Prasocuris junci Local 1 Prasocuris phellandrii Local 1 2 2 1 Anisosticta Coccinellidae novemdecimpunctata Local 2 2 2 2 1 1 2 2 3 2 2 2 2 2 2 1 1 2 2 Coccidula rufa Common 1 2 4 1 1 2 3 2 1 2 1 1 3 1 1 1 1 2 2 1 1 1 1 Coccidula scutellata Local 1 Subcoccinella vigintiquattuorpunctata Common 1 Tytthaspis sedecimpunctata Local 1 Curculionidae Thryogenes nereis Local 1 Staphylinidae Paederus riparius Local 1 Stenus binotatus Common 1 2 1 5 3 1 1 1 2 2 2 Stenus boops Common 1 1 1 1 1 1 2 3 2 2 Stenus cicindeloides Local 1 3 3 1 3 1 11 5 1 2 1 6 3 Stenus fornicatus Nb 2 1 1 1 1 1 2 1 1 1 Stenus fulvicornis Common 1 Stenus impressus Common 5 1 1 Stenus incrassatus Local 9 3 6 1 1 1 Stenus juno Common 2 1 1 1 1 Stenus latifrons Common 1 3 1 Diptera Gymnopternus Dolichopodidae chalybeus Local 1 Ephydridae Coenia curvicauda 1 Coenia palustris 1 2 1 1 1 1 1 1 Notiphila cinerea Common 1 1 Notiphila maculata 1 Notiphila riparia 1 1 1 1 1 1 1 1 1 1 Parydra pusilla 1 Pelina aenea 1 Pelina similis 1 1 Scatella stagnalis Common 1 Scatella tenuicosta Common 1

Order / Family Species Status SQI Field and channel type 2 3 5 6 7 9 10 11 12 13 16 17 20 O Gb O Gc Gcc N O Gb N O P Gb N O P N P Gb Gc N O Gb N O Gc N O Gc N O P N P N O Lonchopteridae Lonchoptera bifurcata Common 1 Sepsidae Themira putris Common 2 Themira superba Local 1 Tabanidae Chrysops relictus Common 1 Hemiptera Lygaeidae Ischnodemus sabuleti Common 1 1 1 1 2 Miridae Heterotoma planicornis Common 1 Saldidae Chartoscirta cincta Common 1 3 5 4 3 1 4 1 3 2 1 5 1 5 5 9 5 6 1 4 6 1 3 1 1 1 1 1 1 1 Saldula saltatoria Common 1 2 Vertebrates Gasterosteus Gasterosteidae aculeatus Common 2 2 2 2 2 2 2 2 2 Pungitius pungitius Common 2 2 2 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Salamandridae Triturus vulgaris Common 1

Appendix 5. Environmental data Variables that were the same for all samples were excluded. Samples are grouped by channel type. Channel types: B – blind gutter, C – connected gutter N – new ditch, O – old ditch, P - pond

Channel type B B B B B C C C C C N N N N N N N N N N O O O O O O O O O O P P P P P Field 3 6 7 11 12 5 5 11 13 16 5 6 9 10 11 12 13 16 17 20 2 3 5 6 9 11 12 13 16 20 6 9 10 16 17 grazed 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 Tall grass/reed 5 3 5 4 5 4 5 4 5 5 5 3 3 5 5 5 5 5 3 5 5 4 5 5 5 5 5 5 5 4 3 5 5 5 5 Short grass 2 5 4 4 4 4 4 4 1 1 4 5 5 4 4 4 1 0 4 3 5 4 2 2 2 3 4 2 0 2 4 0 2 1 4 Bare ground 0 2 0 1 0 2 0 0 0 0 0 0 1 1 2 0 0 0 0 3 0 1 0 1 0 1 0 0 0 0 0 0 0 2 2 Tall herbs 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 3 0 0 3 0 3 0 0 0 0 5 0 0 0 1 0 Scrub 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 0 0 0 4 2 0 0 0 0 0 Shaded 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 5 0 0 0 0 0 Years since last cleared 5 3 5 5 0 5 5 5 5 5 5 4 5 5 5 5 5 5 5 4 10 10 10 10 10 10 10 10 2 10 5 3 5 4 4 Water relative to normal -10 0 0 -10 0 -10 -10 0 -10 0 -10 0 -5 0 -5 -10 0 0 0 0 -10 -10 -5 -10 -10 0 -5 0 0 -10 0 -10 -5 -10 0 Grazing 1 3 0 1 2 1 0 2 0 0 0 3 2 2 2 2 0 0 3 0 3 2 0 2 1 1 3 0 0 0 0 0 0 0 0 Poaching 0 3 0 1 1 0 0 0 0 0 0 1 1 2 1 2 0 0 1 0 2 0 0 1 0 1 1 1 0 0 0 0 0 0 0 Block formation 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 1 1 0 0 0 0 0 0 0 Shelf formation 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 3 0 0 0 0 2 0 0 0 0 0 0 Tangled 1 2 1 2 1 1 1 1 1 1 1 2 1 2 2 2 1 2 1 2 2 2 1 1 1 1 1 1 2 1 0 0 0 0 0 Grassy margin 2 3 0 2 0 0 0 2 1 1 0 1 2 2 2 1 1 3 2 0 1 0 0 0 1 1 1 1 0 0 0 0 0 0 0 Water width 1.5 1 0.5 1 1 1 1 1.5 1 0.5 1.5 0.7 1.5 2 1.5 1.5 1 1.5 1 3 2 3 3 2 3 3 3 5 4 3 0 0 0 0 0 Banktop width 2 2.5 2 2 2 1 2 2 2 1 2 2 2 2 2 2.5 2 2 2 5 5 5 5 2.5 5 4 5 7.5 5 5 0 0 0 0 0 Freeboard 20 20 30 20 40 20 30 20 30 30 30 40 20 20 20 30 20 30 20 0 50 30 20 30 30 20 20 30 20 60 0 0 0 0 0 Water depth 2 5 5 5 20 3 5 25 5 1 5 10 30 55 30 20 30 30 30 70 60 80 90 60 130 110 100 100 130 60 5 5 0 0 0 Silt depth 10 0 10 10 5 0 0 0 5 5 25 0 5 0 5 5 5 5 5 10 40 50 50 100 30 50 50 50 10 20 10 10 0 0 0 Conductivity 0.52 0.33 0.38 0.38 0.51 0.31 0.45 0.35 0.52 0.69 0.3 0.64 0.42 0.44 0.46 0.58 0.34 0.57 0.53 0.76 0.6 0.59 0.69 0.7 0.69 0.69 0.73 0.57 0.77 0.83 0.24 0.58 0.49 0.68 0.55 pH 7.97 8.15 7.23 7.86 7.97 7.87 8.3 8.24 7.86 7.84 8.3 7.85 7.78 8.06 8.34 7.91 8 7.49 8.31 7.96 8.06 7.44 8.54 8.4 8.16 8.22 8.02 7.49 7.983 8.18 7.42 7.82 8.1 8.45 7.93 temperature 25.3 22 27.3 22.3 21 20.7 22.7 19.7 17.9 20.3 18.5 26.5 13.4 18.8 18.8 21.4 16 18.1 17.2 14.8 26 25.5 19.1 20.3 19.7 18.5 19.7 20.2 20.3 18.4 26 19.3 18.9 20.3 16.7 slope on sampled side 2 2 2 2 2 2 2 2 2 2 3 2 2 2 2 2 2 2 2 1 2 2 3 4 3 5 2 2 2 5 1 1 0 0 2 Profile under water 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 2 1 2 3 4 4 4 4 4 4 4 3 2 4 1 1 1 1 1 Open water surface 0 2 2 2 3 2 5 2 1 0 2 1 1 2 2 2 2 1 4 1 4 5 2 5 5 4 5 5 5 3 2 1 1 3 5 Floating Lemna/Azolla 5 0 0 2 1 0 1 5 3 4 3 2 5 4 4 1 5 5 3 5 4 2 5 3 2 3 1 3 3 5 1 5 4 1 3 Other floating aquatics 0 0 0 0 0 0 1 0 0 0 0 2 0 0 0 0 0 0 0 0 2 2 3 1 1 0 1 0 2 1 1 0 0 1 0

Channel type B B B B B C C C C C N N N N N N N N N N O O O O O O O O O O P P P P P Field 3 6 7 11 12 5 5 11 13 16 5 6 9 10 11 12 13 16 17 20 2 3 5 6 9 11 12 13 16 20 6 9 10 16 17 Floating algae 0 0 3 2 3 0 0 3 3 0 2 1 0 0 3 2 0 0 3 1 2 0 0 0 0 0 0 0 0 0 2 3 2 4 0 Submerged plants 0 0 0 0 0 0 1 0 0 0 0 0 0 2 1 0 2 4 4 5 0 0 4 3 1 3 1 2 1 3 1 2 0 5 2 Submerged algae 0 0 3 2 2 0 0 3 0 0 2 0 0 0 3 5 0 0 3 0 0 0 0 0 0 0 0 0 0 0 1 3 0 5 2 Open substrate 0 0 2 2 0 0 5 0 3 4 0 0 0 2 0 0 3 0 0 0 4 4 0 4 4 4 4 4 4 3 3 4 0 0 4 Emergent 3 5 4 2 3 4 0 1 4 1 5 1 2 3 2 3 2 3 1 3 3 3 2 3 1 2 2 3 3 2 5 5 5 2 4 Floating mat 1 5 0 4 0 0 0 2 2 1 0 5 2 3 3 5 2 3 3 2 0 0 0 1 2 0 0 1 0 0 5 0 4 0 0 Exposed vegetated 2 0 0 2 0 0 0 0 3 4 2 3 2 0 2 2 2 2 2 0 0 0 2 0 3 2 2 1 0 0 0 2 0 5 0 Exposed mud 0 2 3 1 0 0 2 0 0 2 0 0 1 0 1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 3 0 4 2 Litter / detritus 1 0 5 1 4 5 0 3 4 4 5 0 1 1 1 3 1 1 0 3 2 1 2 1 1 1 3 1 1 1 2 3 2 0 2 Shaded 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 Emergents/floating mat in channel % 5 0 50 50 5 50 0 0 20 20 95 20 2 10 20 10 5 10 0 5 0 0 0 0 0 0 1 1 0 2 0 80 100 0 0