Bringing Reedbeds to Life Invertebrate Survey of three key reedbed sites in England in 2009, 2010

Royal Society for the Protection of Birds

Description

Bringing Reedbeds to Life is an innovative programme of scientific research and habitat monitoring, coupled with practical habitat management advice and training. It represents one of the largest co-ordinated programmes of such work on reedbed wetlands for over a decade. The project aims to generate a better understanding of the requirements of a wider range of reedbed wildlife. This enhanced understanding will be used to inform advice, training, management and future conservation strategies across England's reedbeds.

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Water traps for aerial invertebrates, pitfall traps for ground-dwelling invertebrates, light traps for Lepidoptera and aquatic netting for aquatic invertebrates were carried out at 3 reedbed sites: Norfolk Wildlife Trust NNR Hickling Broad (Norfolk), Natural England NNR Stodmarsh (Kent), and RSPB NNR Ham Wall (Somerset). Water trap, pitfall trap and aquatic netting surveys were undertaken between June and August 2009. Light trapping for moths was done between June and August 2010.

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The project was led by RSPB with 50% funding from Natural England via the Countdown 2010 Biodiversity Action Fund and working in partnership with other partners such as Wildlife Trusts, The National Trust, Buglife, independent ecological contractors, Butterfly Conservation.

Geographic Description

Sampling points were randomly placed within hydrological strata at least 50 m apart, on three reedbed reserves.

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It is recognised that each dataset is only from one season in one year. The height at which the water trap and moth traps were placed will also have affected which species were recorded.

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Bringing Reedbeds to Life Technical report with further method descriptions will be available after 31st March 2011 at

<a href="www.rspb.org.uk/ourwork/projects/details.aspx?id=tcm:9-210865">www.rspb.org.uk/ourwork/projects/details.aspx?id=tcm:9-210865</a>

Purpose

The aim of the surveys was to relate the numbers of invertebrates caught in traps to the habitat around the traps. This gave an indication of the species that use reedbeds, and the reedbed conditions that favour high biodiversity/ high numbers of rare species/ high numbers of reedbed or wetland specialists species.

Data quality

These data have been gathered by trained field-workers and identified by entomological experts and the data are of a high quality. These data have been mapped and checked for sensitivities and typographical/geographical errors.

Methods

<b>Invertebrates</b>

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<b>Water trap survey methods</b>: Water traps were set at 21 randomly allocated locations at each of the three sites within three hydrological strata based on the best information available. Water traps consisted of a 1.3L plastic food container, painted with "buttercup yellow" plasticote spray paint, with a mesh-covered hole drilled in the side to minimise over-flow. Traps were filled with 500ml of 40% propylene glycol solution to which a couple of drops of washing up liquid were added to reduce surface tension so that invertebrates didn?t float or escape. Each trap was placed on a platform which was nailed to a tree pole at chest height within a circular, 1m radius plot of trampled reed. This trampled reed core was deliberately created to standardise microhabitat influence between trap points. Each trap was protected from bird or vertebrate interference by 2cm garden netting. Traps were active for two weeks in June/July 2009 after which the surveyors collected the contents and reset the traps which were then left in situ for a further two weeks. A habitat survey within the 3 m radius of the trap point was carried out. This included measures of reed structure, distance to scrub, plant diversity, water levels and litter levels.

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<b>Pitfall trap survey methods</b>: Pitfall traps were set at 24 locations at Stodmarsh, 22 locations at Hickling Broad and 12 locations at Ham Wall. Surveys were carried out in August 2009. All sampling points had to be dry during surveys, and Ham Wall had a lower sample size because less dry reedbed was available. Pitfall traps consisted of 400ml plastic flip top containers (Alana Ecology) that were dug in to the ground ensuring that the soil is compact and flush to the rim. The containers were 1/3 full with propylene glycol solution (50%) and a few drops of washing up liquid. Plastic garden mesh covers were pinned over traps to prevent larger creatures falling in and drowning. Pitfall traps were collected 16 days after set up. Samples were washed through filter mesh and stored in 60% Industrial Methylated Spirits. A habitat survey within the 3 m radius of the trap point was carried out. This included measures of reed structure, distance to scrub, plant diversity, water levels and litter levels.

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<b>Moth trap survey methods</b>: Twelve moth trap sampling points at each of the three sites were surveyed for moths in 2010 using Heath type 15 W actinic traps. Points were selected randomly and all available water level information was used to try to ensure a range of hydrological strata were surveyed. Each trap was set three times, at intervals of three weeks between June and August 2010. Four traps were set up each night before dusk and checked at 6 am the following morning to identify species and count individuals. Traps were fitted with rain-guards and used 12 Amp hour batteries, attached to the poles to stay dry. One large egg box tray (roughly 30cm square) ripped into six pieces lined the base of the trap. Traps were fitted firmly to platforms on top of wooden poles as in the water trap survey and pole height was recorded. A habitat survey within the 3 m radius of the trap point was carried out. This included measures of reed structure, distance to scrub, plant diversity, water levels and litter levels.

Aquatic Netting

Netting surveys were carried out for aquatic invertebrates at the three key reedbed sites (Ham Wall, Hickling Broad and Stodmarsh). Reed blocks, open water and ditch habitats were sampled between 13th and 23rd July 2009. The sampling method involved taking 8 samples (that were at least 50 m apart) from each habitat category, sweeping for 5-minutes at each sampling point with a standard pond net (with 1mm mesh). The sample was then placed in a coarse sieve (1cm mesh) placed on a finer sieve (500 microns) which in turn was placed in a white tray and was washed by pouring water over the sample. This was repeated several times. The whole sample was examined to determine abundances of individual invertebrates and numbers of species. Aquatic invertebrates were all identified to species with the exception of certain difficult taxa such as oligochaetes, ostracods, copepods and various Diptera larvae and pupae. A habitat survey of water quality, aquatic vegetation and water body parameters was undertaken. Measures of aquatic invertebrate diversity were: number of species, bootstrapped number of species and abundance of individuals.

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