WENTLOOGE LEVEL INVERTEBRATE SURVEY, 2019 David Boyce

DC Boyce Ecologist October 2019

1. INTRODUCTION

This report details the findings of an invertebrate survey carried out under contract to Green Ecology. The survey aims to assess the importance for invertebrates of the area of Wentlooge Level shown on Figure 2.1 below. The site is in Wales, on the Gwent Levels; an extensive area of grazing marsh on the north-western side of the Bristol Channel. Wentlooge Level lies in the western part of this area, between the cities of Cardiff to the west and Newport to the east. A central grid reference for the site approximates to ST276817.

The grazing marsh ditches of the Gwent Levels support a nationally important assemblage of aquatic plants and invertebrates. It also has one of the last remaining UK populations of the threatened shrill carder bumblebee Bombus sylvarum. For these reasons, much of the area is notified as a series of Sites of Special Scientific Interest (SSSI). The whole of the Wentlooge Level site lies within the Gwent Levels – St. Brides SSSI. Both the shrill carder bumblebee and the brown-banded carder bumblebee Bombus humilis, which also has a strong population on the Gwent Levels, are additionally listed in Section 7 of the Environment (Wales) Act 2016 as Species of Principal Importance for the conservation of biodiversity in Wales.

2. METHODS

The first phase of survey work was undertaken in two blocks of two days, the first session being carried out on the 1st and 2nd of May 2019 and the second on the 22nd and 23rd May. The first session primarily involved sampling the aquatic invertebrate fauna of the ditches (known on the Gwent Level as reens) and the second on survey of the terrestrial fauna. Two further visits were made to the site; on the 8th and 20th of August; the main objective of which was to survey populations of shrill carder bumblebee and brown-banded carder bumblebee. A second aim of the August session was to undertake general invertebrate survey work on an additional area of land at the north-eastern edge of the site (compartment F). This was not included in the initial project specification but was added to the proposed development area subsequent to completion of the May surveys.

Both B. humilis and B. sylvarum are rapidly declining species that have nationally important populations on the Gwent Levels. The latter is now only known from a few places in southern Britain, with grazing marsh levels being one of its most important habitats. For the bumblebee surveys, all Bombus species recorded in each survey unit/sub-unit were noted, with the number of shrill and brown-banded carder bees being counted, along with the flower species at which they were seen foraging. Where possible, bumblebees were identified in the field to species level, with any ‘difficult’ specimens netted for examination in a tube with a hand lens. Fortunately, the shrill carder bumblebee is easily distinguished in the field. Workers of the white-tailed and buff-tailed bumblebees (Bombus lucorum and B. terrestris respectively) are indistinguishable without microscopic examination. As these are both very common and widely distributed, they were recorded as B. lucorum/terrestris workers. Males and queens of these two can be easily identified and were recorded to species level. Note also that B. lucorum is a complex of three very similar sibling species, which are only reliably distinguished by DNA analysis. For the purposes of this study, all records of this taxon refer to the B. lucorum aggregate.

Because it was a relatively large site, it was not feasible in the time available to survey the whole area in detail for invertebrates. The main emphasis for more detailed invertebrate surveys was on those habitats likely to have the greatest invertebrate interest (eg. ditches with shallow margins and a diverse flora; stands of relatively unimproved species-rich grassland; short ruderal vegetation). Other less promising habitat types (eg. shaded and/or dried-out ditches; improved/semi-improved species-poor grassland; species-poor tall ruderal vegetation) were also surveyed, but in less detail, with the aim being to ensure coverage of the range of main invertebrate habitats represented at Wentlooge Level.

In addition to general spot-searching techniques, some more specialised sampling methods were employed to ensure all potentially important habitat features were sampled effectively. The aquatic invertebrate survey was carried out using a simplified version of the standard methods developed for a national survey of the ecology of ditch systems by Buglife (Palmer et al., 2010). Seven ditch lengths were sampled in May 2019. At each of these, three sample points were established that contained habitat thought likely to support rich aquatic invertebrate assemblages. These three samples were considered collectively to constitute a single sample station. Each aquatic sample has been allocated a survey number (ie. AQ1-7) and the location of the sample stations is shown on Figure 2.1.

Before beginning to collect aquatic invertebrates, an eight-figure GPS reading of the location of the sample was recorded. In each sub-sample, a pond net was used to collect material from patches of vegetation that exhibited the greatest small-scale mosaic structure until the net began to fill to the point that it became more difficult to push. This generally took between one to three minutes and the net was usually about a quarter to a third full of plant material (about two to three litres by volume). The sample was then spread out onto a white polythene sheet and invertebrates were recorded/collected for eight to ten minutes as the material was teased apart. Further details of the sampling method can be found in Palmer et al. (2010). Some additional casual aquatic invertebrate sampling was carried out in shallow water margins using a sieve.

The main taxonomic groups to be covered by the aquatic survey were water beetles (Coleoptera), water bugs (Hemiptera), dragonflies/damselflies (Odonata) soldierflies (Diptera: Stratiomyidae) and water snails (Mollusca). Some other invertebrate taxa were also collected where these were easily identified or were in groups familiar to the surveyor (eg. Stenus rove beetles).

For the terrestrial surveys, grassland, wetland and ruderal vegetation was mostly sampled by sweeping with a heavy-duty entomological sweep net or tapping specific invertebrate foodplants over a tray. Ground-active invertebrates in grass tussocks and litter were sampled by shaking them out over a white plastic tray. Catches were collected into tubes with either ethyl acetate or iso-propyl alcohol. The terrestrial invertebrate taxa collected were those that would provide the most useful information on the habitats being surveyed. For example, the ground beetles (Coleoptera: Carabidae) include a number of habitat specialists restricted to eutrophic wetlands such as grazing marsh ditch edges. For the purposes of this survey, a series of six survey units have been identified (survey units A to F on Figure 2.1). These follow the ownership boundaries into which the site is sub- divided. Where there were potentially important invertebrate habitats that warranted more accurate delineation, these ownership units have been further divided into sub-units (eg. A1). These survey units/sub-units are shown on Figure 2.1 below.

Figure 2.1. Location of invertebrate survey units at Wentlooge Level, 2019 3. RESULTS

A full list of all invertebrate species found at Wentlooge Level in 2019 is given in Table 3.1 below, along with their conservation status where applicable, and the survey units in which they were recorded.

Sub-section 3.1 lists all of those species with a formal conservation status that are regarded as key species when assessing the importance of the site for invertebrates. In sub-section 3.2, this provisional list of key species is used to produce a list of key habitat features for invertebrates at Wentlooge Level. Key habitats are defined here as being those that support at least one of the key species identified in sub-section 3.1.

The emboldened status categories given in the table and after the species name in sub- section 3.2 refer to those invertebrates that have a formal rarity/threat status ascribed to them by the UK government conservation agencies. These are defined as follows:

S7 – Species of Principal Importance for the conservation of biodiversity in Wales. These are listed in Section 7 of the Environment (Wales) Act 2016. RDB2 – UK Red Data Book Category 2 – Vulnerable. Taxa which are known from 15 or fewer 10 km squares of the National Grid (hectads) and which are decreasing and will become endangered in the near future if the causal factors continue operating. NT – IUCN Near Threatened. A taxon is Near Threatened when it has been evaluated against the IUCN criteria and does not currently qualify for Critically Endangered, Endangered or Vulnerable status, but is close to qualifying, or is likely to do so soon. Nb. – Nationally Scarce Category B. Taxa thought to occur in between 30 and 100 hectads. This and the Na category have been subsumed into a single NS category in second status reviews. NS. – Nationally Scarce. In second status reviews, the Na and Nb sub-divisions have been subsumed into a single category covering species occurring in 16 to 100 hectads. Unlike the previous ‘N’ category, which covered the same range, this amalgamation does not necessarily result from inadequate information on the British distribution.

Table 3.1. Checklist of invertebrates recorded at Wentlooge Level, 2019 Species scientific name Species English name Status Survey units Bithynia tentaculata Common Bithynia AQ1,3,4,5,7 Valvata piscinalis Common valve snail AQ4 Valvata cristata Flat valve snail AQ4 Deroceras laeve Marsh slug AQ4 Arion ater Large black slug C2 Arion subfuscus agg. Dusky slug C2 Arion intermedius Hedgehog slug C2 Zonitoides nitidus Shiny glass snail D2 Arianta arbustorum Copse snail D3 Cornu asperum Garden snail D2,3 Monacha cantiana Kentish snail D2 Trochulus hispidus Hairy snail D2 Galba truncatula Dwarf pond snail AQ1,4,7; D2 Lymnaea stagnalis Great pond snail AQ1,3,4,7 Lymnaea palustris agg. Marsh pond snail AQ1,3,4,6,7 Radix balthica Wandering pond snail AQ1,3,4 Oxychilus alliarius Garlic snail B3 Aplexa hypnorum Moss bladder snail AQ6,7 Physa fontinalis Common bladder snail AQ1,3,4,5; C1 Anisus leucostoma agg. Button ram’s-horn snail AQ5 Anisus vortex Whirlpool ram’s-horn snail AQ1,3,4,6,7 Planorbarius corneus Great ram’s-horn snail AQ1,4,6,7 Planorbis planorbis Margined ram’s-horn snail AQ1,3,4,7 Oxyloma pfeifferi Pfeiffer’s amber snail A2; AQ1,4,5,6; D2 Succinea putris Large amber snail AQ3 Musculium lacustre Lake orb mussel AQ1,3 Pisidium casertanum Caserta pea mussel AQ1 Sphaerium corneum Horny orb mussel AQ1,3,4 Theromyzon tessulatum A leech AQ4 Glossiphonia complanata A leech AQ1,3 Erpobdella octoculata A leech AQ3,4 Erythromma viridulum Small red-eyed damselfly C1 Coenagrion puella Azure damselfly AQ3; D4 Coenagrion pulchellum Variable damselfy NT. AQ3 Enallagma cyathigerum Common blue damselfly C1 Ischnura elegans Blue-tailed damselfly AQ1; D2 Brachytron pratense Hairy dragonfly A2; AQ1,5; D4 Anax imperator Emperor dragonfly C3 Libellula quadrimaculata Four-spotted chaser AQ3; D2 Orthetrum cancellatum Black-tailed skimmer C3 Sympetrum striolatum Common darter dragonfly A2 Pholidoptera griseoaptera Dark bush-cricket B1 Metrioptera roeselii Roesel’s bush-cricket D3; F1 Conocephalus discolor Long-winged conehead C2,3; F1 Tetrix subulata Slender groundhopper F1 Chorthippus parallelus Meadow grasshopper D2; F1 Chorthippus albomarginatus Lesser marsh grasshopper C2; D3; F1 Tingis ampliata Creeping thistle lacebug F1 Hydrometra stagnorum Water measurer AQ4,7 Microvelia reticulata A Microveliid water bug AQ1,3,7 Nepa cinerea Water scorpion AQ4,6 Ilyocoris cimicoides Saucer bug AQ3,4,5 Notonecta glauca A backswimmer AQ1,3,4 Plea minutissima A Pleid water bug AQ1,3,4 Hespercorixa linnaei A water boatman AQ1,3,4 Hespercorixa sahlbergi A water boatman AQ5,7 Philaenus spumarius Common froghopper C2 Peltodytes caesus A Haliplid water beetle NS. AQ1 Haliplus ruficollis A Haliplid water beetle AQ4,6 Haliplus sibiricus A Haliplid water beetle AQ1,4 Haliplus lineatocollis A Haliplid water beetle AQ3,4 Noterus clavicornis A diving beetle AQ1,3,4,7 Hygrobia hermanni Screech beetle AQ4 Agabus bipustulatus A diving beetle AQ4,5 Ilybius quadriguttatus A diving beetle C1 Colymbetes fuscus A diving beetle AQ5 Nartus grapii A diving beetle AQ1,4,7 Liopterus haemorrhoidalis A diving beetle AQ6,7 Laccophilus minutus A diving beetle AQ3,4 Dytiscus marginalis A great diving beetle AQ3 Hydroporus angustatus A diving beetle AQ1,4,6,7 Hydroporus figuratus A diving beetle AQ6,7 Hydroporus palustris A diving beetle AQ1,3,4,7 Hydroporus planus A diving beetle AQ3,4,6,7 Hydroporus pubescens A diving beetle AQ4,6 Hydroporus tessellatus A diving beetle AQ4,5,6,7 Graptodytes pictus A diving beetle AQ1,4,5 Hygrotus inaequalis A diving beetle AQ4,5 Hyphydrus ovatus A diving beetle AQ3,4,7 Hydroglyphus geminus A diving beetle AQ7 Carabus granulatus A ground beetle D2 Clivina fossor A ground beetle B3 Bembidion assimile A ground beetle D2 Bembidion biguttatum A ground beetle C2 Bembidion articulatum A ground beetle AQ2 Pedius longicollis A ground beetle NS. C2 Pterostichus vernalis A ground beetle D3 Pterostichus strenuus A ground beetle C2 Pterostichus anthracinus A ground beetle NS. AQ4; C2; D2 Pterostichus nigrita ss. A ground beetle AQ6 Amara aenea A ground beetle C2 Amara similata A ground beetle D3 Harpalus rufipes A ground beetle C2 Acupalpus dubius A ground beetle D2 Stenolophus mixtus A ground beetle D2 Stenolophus skrimshiranus A ground beetle NS. D2 Agonum fuliginosum A ground beetle D2 Agonum thoreyi A ground beetle AQ6; B3; D2 Agonum emarginatum A ground beetle D2 Agonum viduum A ground beetle D2 Oxypselaphus obscurus A ground beetle C2 Odacantha melanura A ground beetle NS. AQ6,7 Demetrias atricapillus A ground beetle AQ1; D2 Paradromius linearis A ground beetle A2 Syntomus obscuroguttatus A ground beetle C2; D3 Helophorus aequalis A water beetle AQ1,4,5,6 Helophorus grandis A water beetle AQ5,6,7 Helophorus brevipalpis A water beetle AQ1,3,4,5,7 Helophorus griseus A water beetle AQ3 Helophorus minutus A water beetle AQ1,3,4,5,6,7 Helophorus obscurus A water beetle AQ4,5,6,7 Laccobius bipunctatus A water beetle AQ4,5,6,7; C1 Hydrobius fuscipes A water beetle AQ4,6,7 Anacaena limbata A water beetle AQ3,4,6,7 Anacaena lutescens A water beetle AQ1,3,5,7 Cymbiodyta marginella A water beetle AQ5,7 Enochrus melanocephalus A water beetle AQ4 Enochrus testaceus A water beetle AQ3,4,7 Enochrus coarctatus A water beetle AQ4,5 Helochares lividus A water beetle AQ4 Coelostoma orbiculare A water beetle AQ5; C1 Cercyon ustulatus A water beetle AQ6 Megasternum concinnum A Hydrophilid beetle C2 Hydraena riparia A water beetle AQ4,6 Atholus duodecimstriatus A clown beetle D3 Lesteva sicula A rove beetle B3 Pselaphus heisei A rove beetle C2 Tachyporus nitidulus A rove beetle B3; C2 Tachyporus chrysomelinus ss. A rove beetle D3 Tachyporus dispar A rove beetle C2 Tachyporus hypnorum A rove beetle D3 Tachyporus pallidus A rove beetle A2 Tachyporus transversalis A rove beetle C2 Oxypoda elongatula A rove beetle B3 Dilacra luteipes A rove beetle D2 Cypha discoidea A rove beetle Nb. AQ6 Myllaena intermedia A rove beetle AQ4 Carpelimus erichsoni A rove beetle C1 Carpelimus elongatulus A rove beetle AQ4,5 Anotylus rugosus A rove beetle D2 Stenus pallipes A rove beetle C1 Stenus cicindeloides A rove beetle AQ4,6 Stenus latifrons A rove beetle AQ6,7 Stenus picipennis A rove beetle AQ4 Stenus boops A rove beetle AQ1,4,5; D2 Stenus clavicornis A rove beetle C2 Stenus incrassatus A rove beetle AQ3 Stenus juno A rove beetle AQ7 Stenus melanopus A rove beetle AQ5 Stenus providus A rove beetle C2 Lathrobium fulvipenne A rove beetle AQ6 Sunius propinquus A rove beetle D3 Paederus fuscipes A rove beetle A2; C1,2; E1 Paederus littoralis A rove beetle D3; E1 Paederus riparius A rove beetle A2 Gyrohypnus fracticornis A rove beetle C2 Xantholinus longiventris A rove beetle C2; B3; D3 Erichsonius cinerascens A rove beetle C1 Philonthus albipes A rove beetle C2 Philonthus carbonarius A rove beetle D3 Philonthus micans A rove beetle D2 Philonthus quisquiliarius A rove beetle AQ5; C1,3 Agriotes lineatus A click beetle E1 Agriotes obscurus A click beetle D3; E1 Agriotes sputator A click beetle C2; D3 Rhagonycha fulva A soldier beetle F1 Malachius bipustulatus Common malachite beetle D4 Anthocomus rufus A Melyrid beetle A2; F1 Psammoecus bipunctatus A Silvanid beetle AQ6 Olibrus aeneus A Phalacrid beetle B2; D3 Coccidula rufa A ladybird A2; AQ7; C3 Rhyzobius litura A ladybird C3; D3; E1 Scymnus haemorrhoidalis A ladybird A2; C2 Psyllobora vigintiduopunctata 22-spot ladybird B1; C2 Tytthaspis sedecimpunctata 16-spot ladybird AQ1; C1; D3; E1 Coccinella septempunctata 7-spot ladybird AQ7; D2; F1 Coccinella undecimpunctata 11-spot ladybird D3 Harmonia axyridis Harlequin ladybird B2; D2 Alphitobius diaperinus A darkling beetle D3 Oedemera nobilis An Oedemerid beetle D2 Anthicus antherinus An Anthicid beetle A2 Donacia clavipes A reed beetle C2 Donacia marginata A reed beetle AQ3 Donacia semicuprea A reed beetle AQ1 Plateumaris bracata A reed beetle NS. AQ1 Bruchus loti A seed beetle A2 Bruchus rufipes A seed beetle D2,3 Cassida rubiginosa Thistle tortoise beetle A2; D2 Cassida vibex Knapweed tortoise beetle C2 Gastrophysa viridula Dock leaf beetle A2; D2; F1 Phaedon tumidulus A leaf beetle AQ4; D4 Prasocuris junci A leaf beetle AQ4 Galerucella sagittariae A leaf beetle AQ3,4; D2 Chaetocnema arida A flea beetle AQ1 Chaetocnema concinna A flea beetle C3 Chaetocnema picipes A flea beetle C1 Altica lythri A flea beetle AQ5; D2 Aphthona nonstriata Iris flea beetle A2 Neocrepidodera ferruginea A flea beetle C2 Longitarsus luridus A flea beetle A2 Longitarsus lycopi A flea beetle NS. C1 Apion frumentarium A weevil A2 Perapion hydrolapathi A weevil D3 Ceratapion onopordi A weevil C1 Eutrichapion ervi A weevil B1 Eutrichapion viciae A weevil B1 Ischnopterapion virens A weevil A2; AQ7 Oxystoma pomonae A weevil D2 Stenopterapion meliloti A weevil D2 Protapion assimile A weevil D2 Protapion fulvipes A weevil D2 Protapion nigritarse A weevil D2 Notaris acridulus A weevil AQ4,5 Thryogenes nereis A weevil C2 Tanysphyrus lemnae A weevil AQ4 Gymnetron beccabungae A weevil Nb. C3 Gymnetron villosulum A weevil Nb. C3 Tychius meliloti A weevil D2 Datonychus melanostictus A weevil A2 Microplontus rugulosus A weevil A2; D3 Rhinoncus bruchoides A weevil C3 Rhinoncus perpendicularis A weevil C3; D3 Sitona hispidulus A weevil D3 Sitona lineatus A weevil B1; D2,3 Sitona obsoletus A weevil A2 Sitona suturalis A weevil B1; C2 Hypera rumicis A weevil D2,3 Thymelicus sylvestris Small skipper butterfly C2 Pieris napi Green-veined white butterfly C1 Pararge aegeria Speckled wood butterfly F1 Maniola jurtina Meadow brown butterfly D2; F1 Pyronia tithonus Gatekeeper butterfly F1 Vanessa atalanta Red admiral butterfly D3; F1 Vanessa cardui Painted lady butterfly D2; F1 Aglais io Peacock butterfly C1; E1 Aglais urticae Small tortoiseshell butterfly D3; F1 Lycaena phlaeas Small copper butterfly B1; D3 Aricia agestis Brown argus butterfly A2 Polyommatus icarus Common blue butterfly B1; C2 Nomophila noctuella Rush veneer moth D3 Lasiocampa quercus Oak eggar moth C2 Phragmatobia fuliginosa Ruby tiger moth C2 Tyria jacobaeae Cinnabar moth A2; C2 Noctua pronuba Large yellow underwing C2 Odontomyia ornata Ornate brigadier soldierfly RDB2 AQ1 Odontomyia tigrina Black colonel soldierfly NS. AQ3,5 Oplodontha viridula Common green colonel soldierfly AQ5 Anasimyia lineata A hoverfly AQ6 Episyrphus balteatus A hoverfly D2 Eristalinus sepulchralis A hoverfly C2; D4 Eristalis arbustorum A drone fly C1 Eristalis intricarius A drone fly A2 Eristalis pertinax A drone fly C1 Eristalis tenax A drone fly A2; AQ6; F1 Helophilus hybridus A sun fly C3 Helophilus pendulus A sun fly C2 Helophilus trivittatus A sun fly A2; C2 Parhelophilus frutetorum A hoverfly AQ2 Scaeva pyrastri A hoverfly D2 Sphaerophoria scripta A hoverfly C1 Syritta pipiens A hoverfly A2; AQ6; C1 Tropidia scita A hoverfly D4 Eriothrix rufomaculata A parasite fly D3; F1 Phasia hemiptera A parasite fly C1 Ectemnius continuus A hunting wasp C3 Philanthus triangulum Bee-wolf F1 Andrena labialis Large meadow mining bee D4 Andrena cineraria Ashy mining bee D4 Apis mellifera Honeybee D2,3; F1 Bombus lucorum White-tailed bumblebee C1,3 Bombus terrestris Buff-tailed bumblebee A2; C1,2,3; E1 Bombus lucorum A1,2,3; B1,2; C1,2,3; Buff-tailed/white-tailed bumblebee workers /terrestris D2,3; F1 Bombus hortorum Garden bumblebee C1,3; D2 A1,2,3; B1,2; C1,2,3; Bombus lapidarius Red-tailed bumblebee D2,3; E1; F1 Bombus hypnorum Tree bumblebee D2 Bombus jonellus Heath bumblebee A2 Bombus pratorum Early bumblebee D2 A2,3; B1,2; C1,2,3; Bombus humilis Brown-banded carder bumblebee S7. D2,3 A1,2,3; B1,2; C1,2,3; Bombus pascuorum Common carder bumblebee D2,3 Bombus sylvarum Shrill carder bumblebee S7/Nb. A2,3; B2; C1,2,3; D3 Lasius niger Black garden ant C2; D2 Myrmica rubra A red ant D2 Crangonyx pseudogracilis A freshwater shrimp AQ3,4,6,7 Asellus aquaticus A water louse AQ1,3,4,6,7 Trichoniscus pusillus Common pigmy woodlouse D2 Oniscus asellus Common shiny woodlouse C2; D2 Philoscia muscorum Common striped woodlouse E1 Porcellio scaber Common rough woodlouse D3 Armadillidium vulgare Common pill woodlouse D2,3 Larinioides cornutus An orb-weaving spider C2 Pisaura mirabilis Nursery web spider D2

3.1. Key invertebrates at Wentlooge Level, 2019

In all, 15 key species were recorded at Wentlooge Level in 2019. The emboldened status categories given after the species name are explained in the following paragraph. Two species currently having Nationally Scarce status have been excluded from this list. They are the rove beetles Carpelimus erichsoni and Paederus fuscipes, both of which are now known to be sufficiently frequent not to justify a conservation status.

3.1.1. Variable damselfly Coenagrion pulchellum (Vander Linden, 1825). NT. The variable damselfly is one of a group of very similar-looking blue damselflies. It is most easily distinguished from its congeners by examination of the shape of the pale stripes on the thorax, which are broken to form an exclamation mark shape. Also, the males usually have the black mark on the second abdominal segment in the form of a ‘U’, with a stem connecting this to the transverse band at the apex of the segment. C. pulchellum is widely but very locally distributed across England and Wales, with some further populations in southern and western Scotland. It is usually found in well-vegetated pools and ditches in eutrophic wetlands such as fens and grazing marshes. In May, a few recently emerged specimens were noted amongst much more abundant azure damselflies (C. puella) along the Horsecroft Reen (AQ3). It is likely that survey in June-July would have revealed this species to be more widely distributed at Wentlooge.

3.1.2. A Haliplid water beetle Peltodytes caesus (Duftschmid, 1805). NS. P. caesus is a small yellow-brown Haliplid water beetle with diagnostic pointed tips to the coxal processes. It is a very characteristic species of coastal grazing marshes, where it favours well-vegetated ditches with a soft muddy bottom. It can also be found less frequently in nutrient-rich bodies of still water at inland sites. Sometimes P. caesus can be found in mildly brackish conditions, though most sites are in freshwater. Both adults and larvae feed on filamentous algae and possibly also stoneworts. P. caesus is very scarce, with most recent records from grazing marsh ditches in south-east England and East Anglia. It is a southern species that has not been found north of Lancashire. In the west, its main strongholds are on the Somerset and Gwent Levels. Elsewhere in Wales, it is a great rarity with just a couple of sites. In 2019, this beetle was only recorded from sample station AQ1.

3.1.3. A ground beetle Pedius longicollis (Duftschmid, 1812). NS. This is a medium-sized ground beetle, which can be distinguished from a number of similar species in the closely related genus Pterostichus by its all-red legs and antennae, heavily punctured pronotal base with a single fovea on each side of the mid-line and unfurrowed tarsi. It is very locally distributed across southern England, with concentrations of records in the lower catchments of the Rivers Severn and Thames. In Wales, it is extremely scarce, with just a handful of sites in the south-east close to the Bristol Channel. It favours damp, clayey soils close to still and running water. At Wentlooge a single adult was collected in species-rich, semi-improved grassland at sample station C2.

3.1.4. A ground beetle Pterostichus anthracinus (Panzer, 1795). NS. The Carabid genus Pterostichus has around twenty British representatives, most of which are very ‘typical’-looking, black ground beetles. P. anthracinus is a medium-sized species, with faintly sinuate pronotal hind angles and a characteristically punctured last abdominal sternite. It is one of a suite of ground beetles that are restricted to relatively undisturbed wetlands. It is a fenland specialist throughout its British range, which is primarily found to the south-east of the Severn-Wash line, though there are also isolated colonies in south Wales, and as far north as southern Scotland. Adults were collected from ditch margins in sample stations AQ4, C2 and D2.

3.1.5. A ground beetle Stenolophus skrimshiranus Stephens, 1828. NS. The genus Stenolophus includes three British species, with S. skrimshiranus distinguished from its congeners by the predominantly orange-brown colouration of its elytra and the continuation of the lateral bead on the pronotum around the hind angles. It is a very scarce species, which has its main distribution in the lowlands of southern England, from Dorset eastwards and north through East Anglia to south Lincolnshire. Elsewhere, there is a smaller stronghold on the grazing marsh levels of Somerset and Gwent. There are also a very few sites elsewhere in south-west England. It is a specialist of eutrophic wetlands, such as fens and grazing marshes that is usually found in litter or on the ground amongst tall fen vegetation. A single adult was collected amongst common reed Phragmites australis at the edge of the ditch in sub-compartment D2.

3.1.6. A ground beetle Odacantha melanura (Linnaeus, 1767). Nb. There is only one British species of Odacantha and it is unmistakeable, having bright red elytra and legs, with most of the rest of the body being black, with a metallic blue or green reflection. It is a specialist inhabitant of reed-beds and other types of tall fen vegetation. It has its main British populations in the fen country of East Anglia and in south-east England. In the west, it is confined to the Somerset Levels, the Gwent Levels and Crymlyn Bog, Glamorgan. There is a healthy population of this species along the Phragmites and Glyceria maxima-choked ditches at sample stations AQ6 and 7.

3.1.7. A rove beetle Cypha discoidea (Erichson, 1839). Nb. The nine British species of Cypha are all very small, shiny, globular rove beetles. C. discoidea has the antennae, elytral disc, thoracic margins and abdominal apex yellow, in contrast to the pitchy black colour of the rest of the body. The form of the male aedeagus is very useful in ensuring accurate identification. It is almost confined to south-east England and East Anglia, though there are a few sites in the Midlands and it has recently been discovered on the Somerset Levels. Most often it is found in dense litter in reedbeds and other tall fen habitats. At Wentlooge, a single specimen was found in reed litter in tall fen at the edge of a ditch in sample station AQ6.

3.1.8. A reed beetle Plateumaris bracata (Scopoli, 1772). NS. P. bracata is a large, metallic green or violet reed beetle in which the thorax is strongly narrowed towards the base with conspicuous prominences behind the anterior corners. It is a very scarce species in Britain, with records confined to scattered localities in southern Britain, north as far as the Midlands. In Wales, it is very localised, with most recent records coming from sites near the south coast. This is a phytophagous species, which feeds on young leaf shoots of common reed Phragmites australis. It is found in a range of places where its hostplant occurs, including fens, lake and canal margins and grazing marshes. At Wentlooge, a single specimen was collected on common reed growing at the edge of sample station AQ1.

3.1.9. A flea beetle Longitarsus lycopi (Foudras, 1860). NS. The large flea beetle genus Longitarsus is the most speciose within the Chrysomelidae, with over 40 British species. All are small and many closely resemble each other. L. lycopi is one of a group of species in which the frontal sutures are well marked. The ground colour is reddish with the head, thorax and hind femora pitchy and a thin brown sutural stripe down the centre of the elytra. The shape of the male aedeagus or female spermatheca provides an additional confirmatory character. Its UK distribution is centred on sites in southern England, though it appears to be absent from the south-west peninsula. There are also a few localities in eastern Wales and a handful of outliers in northern England and Scotland. It feeds on a range of Lamiaceae, including common calamint Clinopodium ascendens, wild basil Clinopodium vulgare, ground ivy Glechoma hederacea, gipsywort Lycopus europaeus and mints Mentha spp. It is found in a range of open habitats, including wetlands, calcareous grassland and woodland edges and clearings. At Wentlooge, adults were quite frequent on water mint Mentha aquatica growing in a band of grazed fen at the edge of the pool in sub-compartment C1.

3.1.10. A weevil Gymnetron beccabungae (Linnaeus, 1760). Nb. This is one of two species of Gymnetron that have a dense coating of yellowish scales on the sides of the pronotum. It can be distinguished from the closely similar G. veronicae by the more strongly rounded sides of the pronotum, the more extensive covering of yellowish scales on the thorax and the less conspicuous hair-like scales on the elytra. Also, the elytra of this species usually have a large red mark. It is widely but very locally distributed across the UK in wetlands where there are good populations of its foodplants. It feeds on wetland speedwells Veronica spp., with brooklime Veronica beccabunga being especially favoured. At Wentlooge, a single individual was tapped from pink water-speedwell Veronica catenata, in company with a number of individuals of G. villosulum (see below).

3.1.11. A weevil Gymnetron villosulum Gyllenhal, 1838. Nb. G. villosulum is a small, weevil with black elytra, which is most easily distinguished from its congeners by the dense yellowish setae covering the elytra. G. villosulum has a very scattered distribution across southern England, with almost all records being to the south- east of a line joining the Severn and Humber estuaries. It feeds on water-speedwells Veronica spp, the larvae developing within galled seed capsules. At Wentlooge Level, a number of adults were found on plants of pink water-speedwell growing at the edge of the pond in sub-compartment C3.

3.1.12. Ornate brigadier soldierfly Odontomyia ornata (Meigen, 1822). RDB2. The adult of this soldierfly is a large, striking insect with variably sized orange wedges on the abdomen. The larvae are large and very elongated, with a long last segment in which the anal slit is placed in the middle. It shows a strong affinity with grazing marsh ditches, though there are a very few colonies at inland fen sites. The main British strongholds of the ornate brigadier are on the Somerset and Gwent Levels, though it also has sizeable populations on coastal grazing marshes in East Sussex, and a scatter of other colonies in southern England and East Anglia. O. ornata was recorded at sample station AQ1 at Wentlooge in 2019.

3.1.13. Black colonel soldierfly Odontomyia tigrina (Fabricius, 1775). NS. With its black body and dark wing venation, this mid-sized soldierfly is easily distinguished. It is found in fens at the margins of ponds and ditches. Larvae are aquatic, developing in shallow waterbodies or water margins of ditches and pools where there is dense emergent vegetation. Nationally, O. tigrina is mainly a species of southern England, which becomes rarer in the north, although it also occurs at coastal sites in south Wales and has been recorded from Scotland. At Wentlooge, larvae were collected in the pond net samples from ditches WLAQ3 and WLAQ5.

3.1.14. Brown banded carder bumblebee Bombus humilis Illiger, 1806. S7. This is a medium-sized, pale ginger-brown bumblebee, lacking any trace of black hairs on the abdomen (unlike the common Bombus pascuorum, which it resembles), and possessing a few black hairs above the wing base (these being absent in the very similar Bombus muscorum). B. humilis is associated with large expanses of tall, open, flower-rich grasslands. Pollen is collected from a variety of plants, although species such as clovers, labiates, knapweeds and red bartsia are preferred. Queens emerge from hibernation in May and early-June. Workers are active from June to September, and males appear in August and September. Small nests are constructed on the ground in moderately tall, but non-tussocky grassland, and are covered with moss and dead grass gathered initially by the queen and later by workers. Nests seldom contain as many as 100 workers. B. humilis is a southern species in Britain, with most records from the south and west coasts of England and Wales. The most northerly recent British records are from Anglesey, although old localities extend north to Cumberland. B. humilis has suffered a considerable decline and is now absent from many former sites, particularly away from the coast; the large population on Salisbury Plain, Wiltshire is much the largest extant inland colony. Because of its decline, B. humilis is included on Section 7 of the Environment (Wales) Act 2016 as a Species of Principal Importance for the conservation of biodiversity in Wales. At Wentlooge Level, the 2019 survey showed it to have a wide distribution across the site, with most records coming from areas of relatively flower-rich grassland. Full results are presented in sub-section 3.4.

3.1.15. Shrill carder bumblebee Bombus sylvarum (Linnaeus, 1761). S7/Nb. The shrill carder bumblebee is a relatively small and distinctive bumblebee. The ground colour is a buff-grey, with a poorly defined black band across the centre of the thorax and a reddish-orange tail. Like other scarce bumblebees, it needs large expanses of open flower- rich habitats. Pollen is collected from a wide range of plants, with clovers, vetches, labiates (marsh woundwort being a particular favourite on the Gwent Levels), knapweeds and thistles being some of the most frequently visited. Nests are constructed out of moss and dead litter on the ground surface, or just under it in old vole runs in rather denser, cooler grassland sites than those used by B. humilis. Queens appear in mid-May, with workers primarily foraging from late-June and males flying in August and early-September. Like the brown-banded carder bumblebee, B. sylvarum is a southern species in Britain, though there were formerly scattered populations north as far as the Scottish border. It has undergone a very severe decline in its British range, which formerly included much of Wales and southern England. Remaining populations are restricted to a few areas: mainly the Thames Estuary, Somerset and Gwent Levels and the Pembrokeshire coast. It may have been lost recently from Salisbury Plain. At Wentlooge Level, survey in 2019 showed it to have a scattered distribution across the site, with most records coming from areas of relatively flower-rich grassland. Full results are presented in sub-section 3.4.

3.2. Key invertebrate habitats at Wentlooge Level, 2019

3.2.1. Open reen and pool margins Associated key species: Pterostichus anthracinus; Longitarsus lycopi; Gymnetron beccabungae; G. villosulum; black colonel soldierfly.

This habitat feature encompasses a range of relatively open wetland habitats at the edge of reens and pools. Its structure usually comprises mosaics of tall fen, shorter wetland vegetation (eg. sweet-grasses Glyceria spp., lesser water-parsnip Berula erecta, tubular water-dropwort Oenanthe fistulosa, water mint and celery-leaved buttercup Ranunculus sceleratus), bare mud and shallow open water. It is one of the richest wetland invertebrate habitat features on grazing marsh ditch systems, with five key species associated with it at Wentlooge in 2019. Such habitats are usually a result of grazing and/or recent ditch clearance works. Along more mature ditch and pool margins, this habitat feature is most often maintained by the grazing and poaching activities of cattle or horses, with the latter being most important at Wentlooge.

Shallow water margins and bare mud maintained by stock trampling are used by many important invertebrates. For example, the water-speedwells that are the foodplants of the two Nationally Scarce weevils G. beccabungae and G. villosulum need patches of bare mud for germination of new plants. Likewise, larvae of the black colonel soldierfly are most often found in very shallow, poached water margins. Grazing also controls the growth of tall emergent monocotyledons such as common reed and therefore allows the development of a more diverse flora including lower-growing herbs such as the water speedwells and water mint. The latter is very characteristic of grazed late-successional ditch edges at Wentlooge. It is very important for both phytophagous invertebrates such as the flea beetle L. lycopi (a key species) and as a late-season nectar source for many invertebrates, including the threatened shrill and brown-banded carder bumblebees. Good examples of this habitat feature were sampled at AQ1, A1-3 and C1-3.

The establishment of a solar farm here will inevitably prevent grazing by cattle or horses. It is therefore very important that future management should seek to replicate this habitat feature by other means. Primarily this would be by the adoption of a programme of ditch management works that might include one or more of the following measures. During rotational ditch clearance, excavation should aim to create flat shelving margins, shallow embayments or gently sloping bank profiles (c.30-45ᶛ) during ditch clearance works. The creation of shallow pools where a similar ongoing management regime operates might also meet these objectives. Tree and shrub cover along such ditches should be kept to a minimum, as most of the important invertebrates associated with this habitat feature require open conditions. Excessive growth of bramble, tall herbs and monocotyledons may also need to be cut back on a regular basis. Cutting ditch vegetation should be undertaken during the period from autumn to early spring. Cut material should be moved to an area of low ecological interest away from the ditch corridor, as run-off from rotting vegetation may otherwise reduce water quality. When cutting reeds and other tall emergent vegetation, it should be borne in mind that these constitute a valuable invertebrate habitat in their own right (see sub-section 3.3.4) and retention of significant areas as part of the management framework for the site is important in maintaining and enhancing overall invertebrate diversity.

The great majority of the smaller field ditches at Wentlooge have become very choked with common reed and other rank vegetation and/or are heavily shaded by trees and scrub. There is an opportunity to increase the resource of open reen habitat significantly by implementing the relevant management prescriptions outlined in the preceding paragraph. Most of these ditches are currently of low interest for invertebrates and bringing them back into an active management rotation that aims to allow the development of the full range of important stages in the faunal succession should represent a major biodiversity planning gain.

3.2.2. Aquatic habitats in open mid-successional reens Associated key species: Variable damselfly; Peltodytes caesus; ornate brigadier soldierfly.

This habitat feature encompasses the aquatic invertebrate assemblage of open reens that have been cleared out quite recently, but where sufficient time has elapsed for an abundant flora of submerged macrophytes (mainly fine-leaved pondweeds at the Wentlooge sites) to re-colonise. The most important ditch of this type for invertebrates surveyed in 2019 was AQ1, at the extreme western edge of the site. It also has a horse-poached margin on its eastern bank, with shallow water areas and a diverse floating and emergent flora. Shallow water microhabitats are of key importance for many of the scarcer invertebrates found on the Gwent Levels (see 3.2.1 above).

The other important ditch for this invertebrate assemblage is the Horsecroft Reen, which was sampled in two places (AQ3 and AQ4). However, this has been cleared out very recently and has not yet reached the successional stage where it has been colonised by a rich fauna (though one key species, the variable damselfly was recorded here). An earlier aquatic invertebrate survey of the Horsecroft Reen by Countryside Council for Wales had shown this ditch to support a diverse assemblage similar to that in AQ1 and this should re- colonise over the next few years given sympathetic management.

Similar management prescriptions apply to those outlined in the preceding sub-section. The maintenance of a regular programme of rotational clearance is one of the key requirements, with this carried out over a sufficient period to maintain a substantial resource of reens with an open water column and well-developed aqautic vegetation across the site. In such situations, tree and shrub cover should be removed to minimise shading of the water column.

3.2.3. Species-rich grassland Associated key species: Pedius longicollis; brown-banded carder bumblebee; shrill carder bumblebee.

Fields C1, C2 and C3 still support stands of semi-improved neutral grassland with a diverse flora that includes an abundance of flowering herbs such as common knapweed Centaurea nigra, bird’s-foot trefoils Lotus spp., red clover Trifolium pratense, tufted vetch Vicia cracca and meadow vetchling Lathyrus pratensis. There are other stands of this vegetation, which are heavily grazed by horses and of somewhat lower quality in fields A1, A2 and A3.

These areas are of particular importance for foraging (and probably also nesting) shrill and brown-banded carder bumblebees. Both units A and C were horse grazed, but on the latter this was at a low enough level to allow abundant summer flowering of species such as red clover and common knapweed that are favoured by these and other bumblebees. The fields in unit A were heavily grazed throughout the spring and summer by horses, resulting in a sward that was very short and sub-optimal for foraging and nesting bumblebees. The Nationally Scarce ground beetle P. longicollis was also recorded in unit C in 2019. It is a species of open grassland sites on a clay substrate, usually near to freshwater.

Elsewhere, most of the site has improved grassland of lower interest for invertebrates. However, where the vegetation still includes abundant flowering plants such as thistles and clovers, it may still be of some importance for foraging bumblebees. For example, shrill and brown-banded carder bumblebees were found in sub-units B2, B3 and D3. These were all fields with agriculturally improved grassland that still had locally abundant stands of red and white clover and/or patches of tall ruderal vegetation with spear and creeping thistles.

Clearly unit C is the core area of importance at Wentlooge and future management should aim to maintain the current herb-rich sward, with an abundance of summer flowering species such as red clover, common knapweed etc. This would be best achieved by continuation of a moderate stock grazing regime, with animals removed over the late-spring to summer period (15th April to 1st September), when bumblebees are foraging and nesting. Alternatively, cutting could be undertaken, provided this was carried out once the scarcer bumblebees have finished nesting (between September and March). To stimulate late flowering, half of the sown area might be cut to 20cm in June then the whole area to 10cm between 15 September and 31 October. If cutting is carried out, it is very important that arisings are removed to prevent a build-up of nutrients that will favour coarse, grassy vegetation at the expense of the shorter flower-rich swards required by bumblebees.

If solar panels are sited within fields, this will prevent grazing by cattle and horses. In such cases, it may still be possible to create buffer strips around the field margins. These could be sown with appropriate flower-rich mixes (eg. clovers, vetches, bird’s-foot trefoils, common knapweed etc.) and cut between September and March. Taller areas of grassland may be particularly beneficial in providing nest sites for shrill and brown-banded carder bumblebees. Shorter flower-rich swards (eg. with much bird’s-foot trefoils and clovers) could be created between/under the solar panels, with these being managed by sheep grazing and/or cutting. Red bartsia and yellow rattle may be useful components of the seed mix in the latter case, both as valuable nectar/pollen sources in their own right and because they are semi-parasites that should help to control the growth of coarser grasses. The re- seeding of solar farms with wildflower mixes has been undertaken elsewhere and at this site, where the majority of the area comprises agriculturally improved grassy swards with very low cover of flowering herbs, it has the potential to be very beneficial to populations of shrill carder bumblebee and many other pollinating insects.

3.3.4. Late -successional ditches with abundant Phragmites and/or other tall emergents Associated key species: Variable damselfly; Pterostichus anthracinus; Stenolophus skrimshiranus; Odacantha melanura; Cypha discoidea; Plateumaris bracata

Late-successional ditches with dense growth of common reed and/or other tall emergents, such as reed sweet-grass Glyceria maxima are the most frequent type of reen at Wentlooge. They have been found to support a diverse terrestrial invertebrate fauna that includes six key species, two of which (the variable damselfly and the ground beetle P. anthracinus) may also be found in more open, grazed ditches and their margins (see sub-section 3.3.1). The remaining four species are specialist inhabitants of tall emergent vegetation. The ground beetle O. melanura is adapted to climb the stems of tall monocotyledons, where it preys upon other small invertebrates, while S. skrimshiranus and C. discoidea are found in the dense litter layer. Examples of this habitat were sampled at sample stations AQ2 and AQ6.

Though this is a valuable invertebrate habitat, it is currently very over-represented at Wentlooge relative to the earlier stages of the ditch succession. Overall, it will therefore be beneficial to begin introducing more of these reens into an active programme of rotational clearance, as they will otherwise quickly become excessively choked with vegetation and detritus. As is the case with less heavily vegetated ditches, the most interesting invertebrate fauna is found in unshaded reens and the removal of trees, shrubs and bramble is another desirable objective of future management.

3.4. Bumblebee surveys at Wentlooge Level, 2019

Table 3.4.1 lists the nine species of bumblebee (including the Bombus lucorum/ terrestris aggregate) that were recorded in 2019. Though it is primarily based on the work undertaken on the 8th and 20th August 2019 (all observations of B. sylvarum and B. humilis being on these dates), it also takes account of bumblebee records made during the May survey. Table 3.4.2 identifies the flowers at which individuals of the two scarce bumblebee species were observed nectaring or collecting pollen in August.

Figures 3.4.1 and 3.4.2 map the respective distribution of all August 2019 records of the two threatened bumblebees Bombus sylvarum and B. humilis across the study site, along with the numbers noted in each unit or sub-unit. Only 17 individuals of B.sylvarum were recorded from Wentlooge Level in 2019. The greatest concentration of records came from unit C, which was unsurprising, as this had the largest stands of relatively unimproved grassland with an abundance of favoured nectar/pollen sources such as red clover and common knapweed. The small number of shrill carder bumblebee workers recorded at this site suggests the breeding population to be small currently. Much of Wentlooge Level has species-poor improved grassland with a dearth of nectar and pollen sources that is sub- optimal for this and other bumblebees.

Table 3.4.1. Bumblebee species recorded at Wentlooge Level, 2019 Species Status No. adults Survey units Bombus sylvarum S7, Nb. 14 A2,3; B2; C1,2,3; D3 Bombus humilis S7 39 A2,3; B1,2; C1,2,3; D2,3 Bombus hortorum - - C1,3; D2 Bombus hypnorum D2 Bombus jonellus - A2 Bombus lapidarius - - A1,2,3; B1,2; C1,2,3; D2,3; E1; F1 Bombus lucorum - - C1,3 Bombus lucorum/terrestris - - A1,2,3; B1,2; C1,2,3; D2,3; F1 Bombus pascuorum - - A1,2,3; B1,2; C1,2,3; D2,3 Bombus pratorum - - D2 Bombus terrestris - - A2; C1,2,3; E1

Table 3.4.2. Flowers visited by scarce bumblebees at Wentlooge Level, 2019 Species No. B. sylvarum No. B. humilis Centaurea nigra 2 13 Cirsium vulgare 5 14 Lathyrus pratensis 1 Mentha aquatica 1 3 Odontites vernus 1 Picris echioides 1 Trifolium pratense 4 28 Trifolium repens 4 4 TOTAL 17 64

The brown-banded carder bumblebee was markedly more frequent, with 64 individuals recorded in 2019. However, it was still very sparsely and locally distributed. As with B. sylvarum, the areas of flower-rich swards in unit C were of primary importance for the brown-banded carder bumblebee at Wentlooge. Table 3.4.2 shows common knapweed, red clover, spear thistle and white clover to be the most frequently visited flowers by both of the scarce bumblebees during the Wentlooge survey. As was the case in an earlier invertebrate survey on the Gwent Levels, this study emphasises the value of flowering thistles as foraging plants for scarce bumblebees.

Figure 3.4.1. Number of shrill carder bumblebees Bombus sylvarum by survey unit

Notes on Tables 2.1 and 2.2: The number in front of the dash is the survey unit and that after refers to the number of B. sylvarum (Table 3.4.1) or B. humilis (Figure 3.4.2) recorded there.

Figure 3.4.2. Number of brown-banded carder bumblebees Bombus humilis by survey unit

4. CONCLUSIONS

As befits an area notified as a SSSI for its invertebrate interest, Wentlooge Levels has an extremely rich fauna that is of at least regional importance. The two features of particular note are:

a) The aquatic invertebrate fauna of the reens. The survey has recorded a number of important species, including the variable damselfly, the water beetle Peltodytes caesus, and the ornate brigadier and black colonel soldierflies.

b) Stands of semi-improved neutral grassland with abundant nectar sources. This survey has found the site to hold populations of both the shrill and brown-banded carder bumblebees.

4. ACKNOWLEDGMENTS

I would like to thank Mark Witherall and Jon Garner of Green Ecology for much help in the planning and execution of this contract and the owners of the land for permission to carry out survey work.

5. REFERENCE

PALMER, M., DRAKE, M. & STEWART, N. 2010. A manual for the survey and evaluation of the plant and invertebrate assemblages of ditches. Version 4. Buglife, Peterborough.