Mitigation and monitoring for the Stour and Orwell Estuaries SPA and SPA Annual Review 2010/11

Harwich Haven Authority

March 2011 Final Report 9W1517

A COMPANY OF

HASKONING UK LTD. ENVIRONMENT

Rightwell House Bretton Peterborough PE3 8DW United Kingdom +44 (0)1733 334455 Telephone Fax [email protected] E-mail www.royalhaskoning.com Internet

Document title Mitigation and monitoring for the Stour and Orwell Estuaries SPA and Hamford Water SPA Document short title Annual Review: 2010/11 Status Final Report Date March 2011 Project name HHA Compliance Monitoring Project number 9W1517 Author(s) Client Harwich Haven Authority Reference 9W1517/PBor

Drafted by Rosie Kelly, Greg Shaw and Emma Mundy

Checked by Chris Adnitt Date/initials check …………………. …1/03/11………………. Approved by Chris Adnitt Date/initials approval ………. …1/03/11…………….

CONTENTS Page

1 INTRODUCTION 1 1.1 Background 1 1.2 Background to the Report 4 1.3 Objectives of Compensation, Mitigation and Monitoring 4 1.4 Detailed Objectives for Mitigation and Compensation 5 1.4.1 Approach channel deepening 5 1.4.2 Trinity III Terminal (Phase 2) Extension 5 1.4.3 Monitoring 6

2 ACTIVITIES TO DATE 7 2.1 Introduction 7 2.2 Approach Channel Deepening: Dredging and Disposal 7 2.3 Approach Channel Deepening: Habitat Replacement 8 2.4 Approach Channel Deepening: Sediment Replacement 8 2.5 Approach Channel Deepening: Beneficial Use Schemes 11 2.6 Trinity III Terminal (Phase 2) Extension: Disposal at Sea 11 2.7 Trinity III Terminal (Phase 2) Extension: Habitat Enhancement 12 2.8 Trinity III Terminal (Phase 2) Extension: Sediment Replacement 12 2.9 Felixstowe South Reconfiguration: Dredging and Disposal 12 2.10 Other Activities and Events 14

3 BATHYMETRIC AND TOPOGRAPHIC DATA 15 3.1 Offshore 15 3.2 Stour and Orwell Estuaries 15 3.3 Hamford Water 28

4 BENTHIC MONITORING 29 4.1 Stour and Orwell Estuaries 29 4.1.1 Annual benthic monitoring 29 4.1.2 Biotope descriptions 30 4.2 Felixstowe South Reconfiguration Monitoring 35 4.3 Inner Gabbard East Disposal Site 37

5 MANAGED REALIGNMENT SITE 38 5.1 Background 38 5.2 Methodology 39 5.3 Results 39 5.3.1 Particle Size Analysis 39 5.3.2 Benthic Community Analysis 40 5.3.3 Vegetation 43 5.3.4 Waterfowl 44 5.4 Conclusion 46

6 TRINITY III HABITAT ENHANCEMENT MONITORING 48 6.1 Background 48 6.2 Methodology 48 6.3 Trimley Enhancement Scheme 51 6.3.1 Introduction 51

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6.3.2 Particle Size Analysis 51 6.3.3 Benthic Invertebrate Univariate Results 51 6.3.4 Benthic Invertebrate Multivariate Results 53 6.3.5 Topography 53 6.3.6 Vegetation 54 6.3.7 Waterfowl 54 6.4 Shotley Enhancement Scheme 55 6.4.1 Introduction 55 6.4.2 Particle Size Analysis 55 6.4.3 Benthic Invertebrate Univariate Results 56 6.4.4 Biomass 57 6.4.5 Benthic Invertebrate Multivariate Results 58 6.4.6 Shotley topographical results 58 6.4.7 Vegetation 60 6.4.8 Waterfowl 60 6.5 Conclusion 61

7 SUSPENDED SEDIMENT CONCENTRATIONS 62 7.1 Monitoring Results 62

8 BIRD DISTRIBUTION AND ABUNDANCE 63 8.1 Background 63 8.2 High water count trends 63 8.2.1 Weather conditions in eastern England 64 8.2.2 WeBS Alerts 65 8.3 Low water trends 66 8.3.1 Wildlife Trust report results 66 8.4 Bird abundance and usage of count sectors 68 8.4.1 70 8.4.2 78 8.5 Harwich Haven Bird Sub-group Meeting 86 8.5.1 General observations 86 8.5.2 High and low water count comparison 86 8.5.3 Other Factors 87 8.6 Bird movements 87

9 STOUR AND ORWELL CONDITION ASSESSMENT REPORT 91

10 FINDINGS AND RECOMMENDATIONS 92 10.1 Findings 92 10.2 Recommendations 94

11 REFERENCES 96

FIGURES Figure 1. Study Area 2 Figure 2 Illustration of placement strategy 8 Figure 3 Overview of LiDAR flow over the Stour and Orwell Estuaries in 2005 16

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Figure 4 Overview of LiDAR flow over the Stour and Orwell Estuaries and Hamford Water in 2010 17 Figure 5 Overview of difference between LiDAR flow in 2005 and 2010 18 Figure 6 Overview of LiDAR flow in 2005 and 2010 in the seven River Stour embayments 19 Figure 7 River Stour Area 1: Difference (2010 minus 2005) 20 Figure 8 River Stour Area 2: Difference (2010 minus 2005) 21 Figure 9 River Stour Area 3: Difference (2010 minus 2005) 22 Figure 10 River Stour Area 4: Difference (2010 minus 2005) 23 Figure 11 River Stour Area 5: Difference (2010 minus 2005) 24 Figure 12 River Stour Area 6: Difference (2010 minus 2005) 25 Figure 13 River Stour Area 7: Difference (2010 minus 2005) 26 Figure 14 Location of sample sites on the Stour and Orwell Estuaries 32 Figure 15 Sample Locations - Felixstowe South Reconfiguration Monitoring 36 Figure 16 Mean phi for Trimley samples for surveys 13 to 19 39 Figure 17 Mean number of individuals of benthic macrofauna recorded per core for each survey between survey 1 and survey 20 40 Figure 18 Mean Shannon-Weiner diversity index (H’) for each survey between survey 1 (June 2001) and survey 20 (September 2010) 41 Figure 19 Blotted wet-weight biomass (g) of polychaetes and molluscs in all samples between survey 1 (June 2001) and survey 20 (September 2010) 42 Figure 20 MDS Plot of Bray-Curtis similarity index for average of sites, over all surveys 43 Figure 21 SPA qualifying waterfowl mean numbers at Trimley Managed Realignment Site (sector 31), 2000/01 to 2009/10 (SWT, 2010) with mean abundance for the whole Orwell Estuary 46 Figure 22 Location of sample stations for Trimley and Shotley enhancement schemes 50 Figure 23 Location of topographic transects for Trimley and Shotley 37 Figure 24 Contribution of each major group to the overall observed blotted wet-weight biomass (g) of the samples at Trimley recharge (1-5) and reference (11- 13) sites between survey 5 (June 2005) and survey 15 (September 2010) 52 Figure 25 Mean and peak waterfowl abundance at Trimley Recharge Site (sector 10) counted at low water, 2000/01 to 2009/10 (SWT, 2010) 55 Figure 26 Contribution of each major group to the overall observed blotted wet-weight biomass (g) of the samples at south Shotley recharge sites (15&16) and reference site (14) between survey 5 (June 2003) and survey 15 (September 2010) 57 Figure 27 Topogrpahic composition of Area 4 (North Shotley) Sites S10 and S16 59 Figure 28 Mean and peak waterfowl abundance at Shotley Recharge Site (sector 30) counted at low water, 2000/01 to 2009/10 (Suffolk Wildlife Trust, 2010) 61 Figure 29 Total number of waterbirds on the Stour and Orwell Estuaries 64 Figure 30 Low water count sectors 69 Figure 31 Mean Number of Shelduck on the Orwell between 2001 and 2010 70 Figure 32 Number of Dunlin on the Orwell between 2001 and 2010 71 Figure 33 Number of Black-tailed godwit on the Orwell between 2001 and 2010 72 Figure 34 Number of Redshank on the Orwell between 2001 and 2010 73 Figure 35 Number of Shelduck on the Orwell per sector between 2001 and 2010 74

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Figure 36 Number of Dunlin on the Orwell per sector between 2001 and 2010 75 Figure 37 Number of Black-tailed godwit on the Orwell per sector between 2001 and 2010 76 Figure 38 Number of Redshank on the Orwell per sector between 2001 and 2010 77 Figure 39 Number of Shelduck on the Stour between 2001 and 2010 78 Figure 40 Number of Dunlin on the Stour between 2001 and 2010 79 Figure 41 Number of Black-tailed godwit on the Stour between 2001 and 2010 80 Figure 42 Number of Redshank on the Stour between 2001 and 2010 81 Figure 43 Number of Shelduck on the Stour per sector between 2001 and 2010 82 Figure 44 Number of Dunlin on the Stour per sector between 2001 and 2010 83 Figure 45 Number of Black-tailed godwit on the Stour per sector between 2001 and 2010 84 Figure 46 Number of Redshank on the Stour per sector between 2001 and 2010 85 Figure 47 Proportion of the movements towards the Orwell Estuary 88 Figure 48 Destinations of the movements from the Orwell Estuary 88 Figure 49 Origins of the movements towards Stour Estuary 89 Figure 50 Destinations of the movements from Stour Estuary 89

TABLES Table 1 Number of deep drafted (> 13.5m) shipping movements at Felixstowe on an annual basis 7 Table 2 Water column recharge in the Stour Estuary 8 Table 3 Water column recharge in the Orwell Estuary 9 Table 4 Subtidal placements at North Shelf 9 Table 5 Total amounts of material placed each year as part of the sediment replacement programme on an annual basis 10 Table 6 Current and revised volumes for silt disposal at Inner Gabbard 12 Table 7 River Stour intertidal volumes and areas derived from the 2005 and 2010 LiDAR data 27 Table 8 Changes in River Stour intertidal volumes and areas between 2005 and 2010 27 Table 9 Biotopes for the Orwell Estuary for the survey in 2008, 2009, 2010 33 Table 10 Biotopes for the Stour Estuary for the survey in 2008, 2009, 2010 34 Table 11 Dates of the vegetation and macrofaunal surveys 38 Table 12 Saltmarsh development at the Trimley site for available surveys since survey 8 (September 2003). 44 Table 13 Wetland Bird Survey Alerts for the Stour and Orwell SPA (to winter 2007/08 inclusive) 65 Table 14 Trends in the mean and peak numbers of species on the Orwell, Stour and SPA 1999/00 to 2009/10 67

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PLATES Plate 5 Saltmarsh development at Trimley Managed Realignment Site from 2001 to 2010 29

APPENDICES

Appendix A Biotope Descriptions

Appendix B Waterfowl Species Accounts

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1 INTRODUCTION

1.1 Background

In October 1998, works to deepen the approach channel to the Haven Ports commenced. The works were completed in April 2000. The Harwich Haven Authority's (HHA) Mitigation and Monitoring Package (MMP) for the scheme (PDE and HR Wallingford, 1998) was included by the Department for Transport (DfT) (formerly the DTLR) as part of their consent for the works under the Coast Protection Act, 1949. The Department for Environment, Food and Rural Affairs (Defra) (formerly MAFF) also issued consents to the HHA for the various sediment placement schemes associated with the package under the Food and Environment Protection Act (FEPA) 1985, which include annual monitoring conditions.

In 2002, consent was granted for the Trinity III Terminal (Phase 2) Extension, which was completed in September 2004. A Compensation, Mitigation and Monitoring Agreement (CMMA) for the extension was produced. FEPA consents were issued for the habitat enhancement schemes and the disposal of capital silts at sea, which included monitoring conditions. Under the CMMA, the HHA undertook to implement the actions set out therein as an agent to the Port of Felixstowe in respect of compensation arising from the quay extension.

The first phase of the Felixstowe South Reconfiguration (FSR) Project, completed in 2010, involved reclamation, new quay construction and widening of the channel adjacent to the reclamation. Although this project did not require a formal CMMA, there was a need to agree detailed monitoring with CEAFS for the disposal sites and the area around the works. This was agreed in July 2008 and was set out in the following documents:

• Specification for Monitoring Biological Communities at Inner Gabbard and Inner Gabbard East Disposal Sites, May 2008, • Specification for Monitoring Biological Communities Local to the Felixstowe South Reconfiguration, May 2008.

Compliance with the actions set out in the compensation packages, the mitigation measures proposed as part of the Environmental Impact Assessment process and the conditions of the FEPA consents for all of the above schemes must be ensured; this responsibility lies with the HHA. An Annual Report is produced presenting the information collated on the various habitat and sediment replacement schemes and monitoring activities during the preceding year. In addition to these Annual Reports, the HHA is required to undertake a more detailed and comprehensive review of conditions within the estuary every five years. In 2005, the first stage of the five-yearly review was compiled using the results of bathymetric surveys completed for the Stour estuary. At the time of its production, bathymetric surveys of the Orwell were not complete. The second stage of the review in 2006 incorporated the results of bathymetric surveys for the Orwell, undertaken that year. Findings from related studies completed since the production of the first review were also presented. The area of study can be seen in Figure 1. The second detailed review will be completed during 2011 when the full analysis of bathymetric and LiDAR data is available and there are four years of benthic data to review. The detailed review will also draw on

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the findings of the additional bird study undertaken during the winter of 2010/11 to look into roosting movements.

This annual review presents summary data of past studies together with new data from the year 2010.

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Figure 1 Study Area

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1.2 Background to the Report

This report is produced primarily to provide feedback to Natural England, the Environment Agency, the DfT and Defra on the results of the HHA’s ongoing monitoring programme. The report also details progress against the objectives of mitigation and a summary of the future strategy for monitoring. The report is one of the management initiatives to ensure compliance with the objectives outlined in the Approach Channel Deepening MMP and the Trinity III (Phase 2) Extension CMMA. It also includes reporting of the findings for the monitoring work carried out as a requirement of the licensing for the Felixstowe South Reconfiguration project.

1.3 Objectives of Compensation, Mitigation and Monitoring

The primary objectives of the compensation, mitigation and monitoring for both schemes are:

1. To avoid any impacts as a result of the works on the favourable conservation status of both habitats, as defined under Article 1(e) of the Habitats Directive, and species, as defined under the Article 1(i); and, 2. To remove any adverse effects arising from the works in order to maintain site integrity in so far as this will be affected by the schemes.

Where ‘favourable conservation status’ is defined as:

Intertidal habitats (i.e. saltmarsh, soft muddy and granular habitats) that, in combination, maintain the geomorphological form and functioning of the estuaries, so that they are capable of sustaining the populations of internationally and nationally important overwintering birds for which the site qualifies.

In 1997 and 2001, when the MMP and CMMA were produced, the qualification of the Stour and Orwell Estuaries SPA was as follows:

Populations of internationally / nationally important overwintering birds, based on:

• Notable numbers of golden plover (under Article 4.1);and • Important populations of dunlin; shelduck; dark-bellied geese; redshank; grey plover; black-tailed godwit; turnstone; ringed plover; wigeon; knot; curlew; pintail; mute swans; goldeneye and scaup (under Article 4.2).

Since qualification in 2003, the boundaries of the constituent SSSIs were extended and in May 2005, the SPA boundary was extended to include an additional 360 hectares. The SPA boundary extensions coincide with areas incorporated within enlarged boundaries of the Orwell Estuary SSSI and Stour Estuary SSSI, as well as the whole of SSSI. Following the renotification of SSSIs in 2003 and the SPA in 2005, the site now qualifies under Article 4.1 of the Wild Birds Directive (79/409/EEC) by supporting 1% or more of the Great Britain population of avocet Recurvirostra avosetta. Over the period 1996 to 2000 the SPA supported 21 breeding

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pairs. It also qualifies under Article 4.2 of the Directive as it is used regularly by 1% or more of the biogeographical populations of a number of migratory species.

The site further qualifies under Article 4.2 as it is used regularly by over 20,000 waterbirds in any season. In the non-breeding season, the site regularly supports around 63,000 individual waterbirds (based on the 5 year peak mean recorded between 1993/94 and 1997/98).

1.4 Detailed Objectives for Mitigation and Compensation

1.4.1 Approach channel deepening

Detailed objectives for mitigation and compensation of the effects associated with the 1998/2000 Approach Channel Deepening have also been defined in order to ensure the achievement of the primary objectives (set out above). They can be summarised as follows:

Stour and Orwell Estuaries To create 16.5 hectares of intertidal habitat (compensation) and to prevent the loss of up to 5 hectares per annum of intertidal habitat due to increased rates of erosion, through sediment replacement (mitigation).

Hamford Water To monitor the system, as appropriate, in order to determine the potential for an effect associated with the dredge to arise, and to define existing sand transport pathways offshore and in/out of Hamford Water.

1.4.2 Trinity III Terminal (Phase 2) Extension

Detailed objectives of the mitigation and compensation for the Trinity III (Phase 2) Extension are as follows:

1. To provide an enhanced level of protection to the seawalls along the Shotley and Trimley frontages by raising the intertidal area; 2. By creating additional protection for the seawalls, to enhance the ecological value of some 23ha of the intertidal habitat (of which approximately 20ha will be intertidal mud and 3ha saltmarsh), replacing the feeding habitat lost due to the immediate effect of the quay extension and dredge over the short to medium term; 3. To raise the level of the intertidal mud, thereby increasing its exposure and providing a feeding habitat for waterfowl for a longer period in the tidal cycle (i.e. increasing the number of bird feeding hours), mitigating the effect of a reduced tidal range; and

Objectives 1 to 3 find expression through the establishment of the Habitat Enhancement Schemes on the Shotley and Trimley foreshores (see Section 2.7).

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4. To offset the predicted increase in the rate of erosion of the intertidal in the Stour and Orwell Estuaries by increasing the existing sediment replacement programme by 5%.

The habitat enhancement schemes (see Section 2.7), proposed in conjunction with the Trinity III Terminal (Phase 2) Extension, also have the following objectives:

1. To increase the stability of the lower Orwell flood defences and provide the opportunity for the development of a long term strategy for the sustainable management of the estuary; and

2. To compensate for any adverse effect on the integrity associated with the works, while not constraining future options for the sustainable management of flood defences and habitats in the estuarine system

1.4.3 Monitoring

Detailed objectives for monitoring have also been defined in order to determine whether or not any impacts on the favourable conservation status of the European site(s) arise as a result of the dredging, quay extension and their associated mitigation schemes. They can be summarised as:

1. To increase understanding of the processes operating in the Stour and Orwell estuaries and Hamford Water and to define those aspects that relate to the deepening; 2. To measure the change in habitat distribution and to understand the relationship between morphology, habitat and the populations and distribution of designated bird species; 3. To validate and refine the mitigation actions; and 4. To fully monitor the effect and thereby success of mitigation.

This report sets out progress against these objectives.

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2 ACTIVITIES TO DATE

2.1 Introduction

This section provides summary information on accretion, dredging volumes, shipping activity and the sediment replacement activities within the estuary system. Information presented here covers only the period 2007-2010 which is relevant to the present FEPA licence. The reader is referred to the previous annual reports for more detail (Harwich Haven Authority, Royal Haskoning and HR Wallingford, 2010).

2.2 Approach Channel Deepening: Dredging and Disposal

Based on HHA dredger records a total of about 1,211,000 dry tonnes of maintenance dredged material from Harwich Harbour was deposited at the Inner Gabbard between 1 January 2010 and 31 December 2010. A further 53,000 dry tonnes was distributed within the estuarine system as part of the sediment replacement programme. The total amount of dredging, based on dredger records, was thus 1,264,000 dry tonnes.

Based on bathymetric records for the maintained area of the Harbour it is estimated that for the period 1 January 2010 to 31 December 2010 the average rate of observed siltation in the Harbour was equivalent to about 8,600 m3/day. This equates to an annual siltation rate of about 3.10M m3. Over the year the backlog of material in the Harbour reduced by about 113,000m3. Thus, based on the bathymetric surveys, about 3.2M m3 of material was removed through maintenance dredging. At an in-situ dry density of 530kg/m3 this is estimated to be equivalent to about 1.7M dry tonnes of material.

From the dredger records described above it is apparent that, during the 2010 calendar year, the total mass dredged from the Harbour and berths was less than the total mass removed when assessed by survey.

Reclamation works, the capital dredge for channel widening and dredging for the berthing areas associated with Phase 1 of the Felixstowe South Reconfiguration project (FSR) were completed in 2010. Approximately 3.1M m3 of material was dredged from the Harbour and about 2.5M m3 of reclamation material was imported from a licensed offshore aggregate site.

Deep drafted vessel movements in Harwich Harbour have declined over the last year. This is summarised in Table 1 which shows the vessel movement and measured accumulation rate data calculated on an annual basis between 2007 and 2010. The average annual observation of rates of accumulation in the Harbour during this period has been about 5,600 m3/day.

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Table 1 Number of deep drafted (> 13.5m) shipping movements at Felixstowe on an annual basis

Period Number of vessel Observed average movements * daily accumulation rates of silt (m3) Jan 1 2007 to Dec 31 2007 112 5,000 Jan 1 2008 to Dec 31 2008 153 4,900 Jan 1 2009 to Dec 31 2009 179 4,100 Jan 1 2010 to Dec 31 2010 112 8,500 Average for period 139 ~5,600 * Draft of 'greater than 13.5m' does not include 13.5m

In 2010 the observed average daily accumulation rate of silt for 2010 was double that observed during 2009 (4,100 m3/day c.f. 8,500 m3/day). It has already been established that, based on previous data, there appeared to be a strong relationship between the number of vessel movements within the Harbour and the daily accumulation rate. During 2010, there were considerably fewer deep-drafted vessel movements than in previous years. It should be noted however that during 2010 in addition to the standard vessel movements to and from the various quays at Felixstowe, Harwich and there were many vessel movements associated with the dredging and construction of the Felixstowe South reconfiguration.

2.3 Approach Channel Deepening: Habitat Replacement

Objective: To create 4 hectares (ha) of intertidal habitat to replace the habitat lost due to the immediate effect of the change on tidal range and to create 12.5ha of intertidal habitat to mitigate losses that could occur before sediment replacement measures can be expected to be fully effective.

The managed realignment site at North Trimley Marsh was completed in February 2001, with the sea wall breached in November 2000. Since the sea wall was breached, ecological surveys have been carried out to monitor the rate at which the site has been colonised by fauna and flora, as well as use by birds and the particle size of sediments. Results of the surveys to date are presented in Section 5.

2.4 Approach Channel Deepening: Sediment Replacement

Objective: To prevent, through the immediate reintroduction of sediment into the system for as long as the channel is maintained, the annual loss of 1.7ha of intertidal (mean springs) (plus 1.1ha from the 1994 dredge) and 3.3ha of intertidal (mean neaps) (plus 2.2ha from the 1994 dredge) due to increased rates of erosion.

Following the 2007 Annual Review Meeting the sediment replacement technique was modified. HHA agreed to place 50,000 dry tonnes of material back into the estuaries on an annual basis. This was to be undertaken by pumped discharge whilst the dredger was underway (35,000 TDS into the Stour and 15,000 TDS into the Orwell) at

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a minimum of 4 knots discharging over a track. In addition subtidal placement at North Shelf was to be reduced to 50,000 dry tonnes per year. This revised sediment replacement strategy commenced in the autumn of 2008. Due to the capital dredging works associated with the Felixstowe South reconfiguration (i.e. widening the north side of the channel in the vicinity of North Shelf) no material has been placed sub tidally at the North Shelf since early April 2009.

The modified concept of placing material along tracks in the Stour and Orwell estuaries is illustrated in Figure 2.

Figure 2 Illustration of placement strategy (commenced early April 2009)

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Stour Estuary

The following water column placements were made in the middle and lower Stour up to the end of December 2010:

Table 2 Water column recharge in the Stour Estuary

Sediment replacement Timing (TDS) Late November 2008 9,000 Late January 2009 8,300 Early April 2009 11,200 Late December 2009 11,400 Mid February 2010 14,700 Early April 2010 10,900 Early November 2010 11,800 Total 77,300

Orwell Estuary

The following water column recharge placements were made in the Orwell estuary, where placements were initiated in 2002:

Table 3 Water column recharge in the Orwell Estuary

Timing Sediment replacement (TDS)

Late November 2008 5,000 Late January 2009 4,200 Early April 2009 4,700 Late December 2009 4,600 Mid February 2010 5,800 Early April 2010 4,400 Early November 2010 5,200 Total 33,900

Lower Harbour

Subtidal placements have been made at the North Shelf by discharging from a trailer suction hopper dredger via the suction pipeline (Table 4). Due to the capital dredging works associated with the Felixstowe South reconfiguration (i.e. widening the north side of the channel in the vicinity of North Shelf) no material has been placed sub tidally at the North Shelf since early April 2009. The possibility of continuing to not place material at this location will be discussed in 2011.

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Table 4 Subtidal placements at North Shelf

Timing Amount placed (TDS) Early August 2008 20,000 Mid November 2008 29,300 Mid February 2008 26,600 Mid April 2008 19,200 Late November 2008 12,800 Late January 2009 15,800 Early April 2009 15,100 2010 0* Total 138,800 * No placement at North Shelf since early 2009

Conclusion

HHA is compliant with the original requirements of the Approach Channel Deepening consent in terms of the in estuary placement. However in terms of the Harbour subtidal placement the placed volumes are presently reduced, consistent with the agreement with the regulators that during the FSR works there would be no placement. This practice has continued since April 2009 (see Table 5).

Table 5 Total amounts of material placed each year as part of the sediment replacement programme on an annual basis

Annual placement TDS within Annual placement TDS to North Period Stour/Orwell (dry Tonnes) Shelf (dry Tonnes)

Jan 1 2007 to Dec 31 2007 132,182 99,901 Jan 1 2008 to Dec 31 2008 89,418 58,597 Jan 1 2009 to Dec 31 2009 44,374 30,832 Jan 1 2010 to Dec 31 2010 52,835 0* * No placement at North Shelf since early 2009

2.5 Approach Channel Deepening: Beneficial Use Schemes

Objective: To meet the FEPA requirement to seek beneficial uses, as far as possible, for the material arising from the channel deepening.

Details of the beneficial use schemes that have been implemented by the HHA were provided in the 2001 Annual Report (PDE and HR Wallingford, 2001) and recorded in the 2003 Compliance Report (Royal Haskoning and HR Wallingford, 2003).

2.6 Trinity III Terminal (Phase 2) Extension: Disposal at Sea

Objective: To allow the construction of the Trinity III (Phase 2) Extension.

Dredging and disposal for this scheme was completed on 28th March 2003. Approximately 500,000m3 was deposited at the Inner Gabbard, with 28,000m3 used to

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feed an Environment Agency beneficial use scheme at Horsey Island. Bathymetric and benthic invertebrate surveys of the Inner Gabbard have since been carried out, the findings of which were reported in the 2004 annual report.

2.7 Trinity III Terminal (Phase 2) Extension: Habitat Enhancement

Objective: To provide an improved level of protection to the seawalls along the Shotley and Trimley frontages through the placement of dredged materials (clay/gravel bunds and silts) and enhance the ecological value of the associated intertidal habitat.

The habitat enhancement schemes for the Trinity III (Phase 2) Extension were completed in October 2003. The schemes utilised about 107,000 dry tonnes of maintenance dredged silts which would otherwise have been placed offshore at the Inner Gabbard disposal site. The schemes comprised the placement of clay and gravel bunds on the Trimley and Shotley foreshores which were backfilled with silt and sandy gravel.

The habitat enhancement schemes are being monitored by Royal Haskoning on behalf of the HHA as part of the Trinity III (Phase 2) Extension CMMA and LiDAR data is now also available. Further details on the construction of the bunds are available in the 2004 Annual Report. A description of the monitoring that has taken place is presented in Section 6.

In addition to the HHA monitoring, a DEFRA research project being undertaken by HR Wallingford and CEFAS looked at the correlation between benthic recovery and physical processes on parts of the site on the Shotley side of the Orwell through intensive benthic and physical process monitoring for 3 years following construction. Monitoring of the site under this scheme ceased in September 2005. The technical reports arising from this project were produced in December 2006.

2.8 Trinity III Terminal (Phase 2) Extension: Sediment Replacement

Objective: To offset the predicted increase in the rate of erosion of the intertidal in the Stour and Orwell Estuaries.

The CMMA for Trinity III (Phase 2) specified that the sediment replacement volumes should be increased by 5% to mitigate the effect of the extension on intertidal erosion. However, in light of modelling on the effects of the Trinity III (Phase 2) Extension, which has showed that the extension is predicted to reduce erosion in the estuary the volume of sediment replacement has not been increased (Harwich Haven Authority, Royal Haskoning and HR Wallingford, 2010)

2.9 Felixstowe South Reconfiguration: Dredging and Disposal

The most significant recent development in the harbour was the work on the first phase of the Felixstowe South Reconfiguration (FSR) project. This involved the construction of a new quay line and reclamation into the harbour from the Oil Jetty towards the

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Landguard Terminal, the demolition of the Oil Jetty and Ro-Ro 1 and 2 and the in-filling of the Dock Basin. The main channel width has been maintained by dredging on the west side of the channel in the region of the Harwich Shelf. A total of some 3.1M m3 has been dredged and about 2.5M m3 of reclamation material imported. The materials arising from capital dredging were placed at two locations, as identified within the FSR Environmental Statement (ES). The two sites are the Inner Gabbard and Inner Gabbard (East) disposal sites, both of which are located offshore of Harwich. Inner Gabbard is a dispersive site and received the dredged silts, whereas Inner Gabbard (East) received the coarser materials.

An increase in volume of silt to be placed at the Inner Gabbard site (as detailed below in Table 6) over that initially applied for was found to be necessary. This resulted from a change in working requirements because of physical conditions at the site. Despite this increase in requirement, it was still considered feasible for disposal to remain well within the 1,000,000 m3 per rolling four week period as set out in the FEPA licence. This was achieved by coordinating maintenance dredging to avoid periods when the disposal of capital dredged material would be taking place.

Table 6 Current and revised volumes for silt disposal at Inner Gabbard

Proposed disposal (m3 silt) Volume*m3

To Inner Gabbard: FSR 140,000 Original HHA maintenance 2,600,000 (2003) Combined total 2,740,000

To Inner Gabbard: FSR 1,200,000 Revised HHA maintenance 2,600,000 (2008) Combined total 3,800,000

Revised total volume increase in silt disposal 1,600,000 Revised total percentage increase in silt disposal 39% *based on maintenance figures from January 06 to December 06

With respect to the Inner Gabbard dispersive site, it was considered that the rate at which dispersal occurs was the significant factor rather than the total quantity deposited. This being the case, and given that the licence requirements could be met as described above, it was considered that environmental consequences should be similar to those impacts already assessed in the FSR ES, for the smaller volume of sediment disposed at the site.

A new licence was issued by the Marine and Fisheries Agency to reflect the revised volumes of material.

Monitoring of the disposal sites was a requirement of the licence conditions. The monitoring of the dredge site and disposal areas was proposed (and approved by CEFAS / Defra) to compliment the methodology of the previous monitoring programmes as well as meet the requirement stipulated in the Schedules to Licences for the disposal operations. This included the monitoring of infaunal communities and particle size distribution as well as bathymetric surveys. The pre-dredge, post-dredge

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and disposal survey work at the FSR site and on both Inner Gabbard and Inner Gabbard East disposal sites has been carried out.

2.10 Other Activities and Events

Objective: To determine if any monitored changes could be due to other activities and events in the estuary system.

Over the period January 2010 to December 2010 there have been two periods of severe cold weather. The second of these events in December 2010 resulted in ice forming on the intertidal areas of the estuaries and associated rafting of ice and increased sediment transport. The maintenance requirements in January 2011 were unusually severe.

In the current reporting period approximately 48,300 dry tonnes of fine silty sand was dredged from the approach channel between Buoys 1 and 2 and placed offshore at Inner Gabbard. This mass has been excluded from the discussion in this section which strictly refers to the masses of muddy material dredged from Harwich Harbour. In 2010 no dredging took place in the Walker Buoy area of the offshore part of the channel.

The Port of Ipswich has modified its maintenance dredging campaign in the present year resulting in greater volumes of maintenance dredging. Materials arising from the maintenance dredging have been placed subtidally in the deeper sections of the main navigational channel in the Orwell Estuary.

It is understood that some material arising from maintenance dredging of the approaches to the Medway has also been placed at the Inner Gabbard during the reporting period.

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3 BATHYMETRIC AND TOPOGRAPHIC DATA

Purpose: To determine the changes in the intertidal and subtidal habitats in relation to the erosion or accretion of sediment.

Bathymetric data should assist in answering the following monitoring objectives (as set out in the Approach Channel Deepening Mitigation and Monitoring Package):

• To define those aspects of system change that relate to the deepening and port development; • To understand the relationship between morphology, habitat and the populations and distribution of designated bird species; • To fully monitor the success of mitigation; • To ensure that the mitigation measures (and beneficial use schemes) do not cause adverse environmental impact; and • To define the extent of each habitat type and to measure change in habitat distribution.

3.1 Offshore

Results of bathymetric survey in the offshore areas were reported in the 2005 Five- Yearly Review report (Royal Haskoning and HR Wallingford, 2005). Bathymetry surveys for Inner Gabbard and Inner Gabbard East (following on from Felixstowe South Reconfiguration works) were completed in late summer 2010.

3.2 Stour and Orwell Estuaries

LiDAR data

LiDAR flights over the Stour and Orwell Estuaries were undertaken in 2005 and 2010. Figures 3 and 4 show the extent of the LiDAR data measured in 2005 and 2010 and Figure 5 shows the difference between the two surveys where common data is available.

As can be seen in Figure 5 the analysis of differences in the LiDAR data flown over the Orwell is dominated by a number of streaks. The source of this streaking is being investigated and the question of whether it is possible to further post-process the data in order to improve the quality is being considered. Provided this can be done, comparisons can be made which will be reported at the next Regulators’ meeting.

The River Stour LiDAR data has been processed between levels of -1m ODN and +2m ODN for the seven different embayments of the estuary as shown in Figure 6.

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Figure 3 Overview of LiDAR flow over the Stour and Orwell Estuaries in 2005

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Figure 4 Overview of LiDAR flow over the Stour and Orwell Estuaries and Hamford Water in 2010

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Figure 5 Overview of difference between LiDAR flow in 2005 and 2010

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Figure 6 Overview of LiDAR flow in 2005 and 2010 in the seven River Stour embayments

The differences in bed levels between the surveys in the 2005 and 2010 LiDAR data for each of the embayment areas is shown in Figures 7 to 13 below.

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Figure 7 River Stour Area 1: Difference (2010 minus 2005)

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Figure 8 River Stour Area 2: Difference (2010 minus 2005)

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Figure 9 River Stour Area 3: Difference (2010 minus 2005)

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Figure 10 River Stour Area 4: Difference (2010 minus 2005)

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Figure 11 River Stour Area 5: Difference (2010 minus 2005)

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Figure 12 River Stour Area 6: Difference (2010 minus 2005)

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Figure 13 River Stour Area 7: Difference (2010 minus 2005)

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For each of the seven areas shown in Figures 7 to 13 the volume and planar area of the intertidal between -1m ODN and +2m ODN has been calculated as shown in Table 7.

Table 7 River Stour intertidal volumes and areas derived from the 2005 and 2010 LiDAR data Stour Intertidal between -1m ODN and +2m ODN Year Area Planar area (m2) Volume (m3) 1 2005 3,575,800 3,770,750 2010 3,575,650 3,955,680 2 2005 1,666,800 1,586,640 2010 1,657,400 1,531,970 3 2005 2,968,600 3,699,470 2010 2,977,100 3,639,890 4 2005 616,850 679,636 2010 615,600 711,173 5 2005 1,341,750 1,621,610 2010 1,335,900 1,575,390 6 2005 448,050 513,669 2010 445,350 520,712 7 2005 2,005,400 1,551,960 2010 2,006,550 1,579,360

Based on the data presented in Table 7 the changes that have occurred in each of the seven areas over the 5 year period are given in Table 8.

Table 8 Changes in River Stour intertidal volumes and areas between 2005 and 2010 Intertidal between -1m ODN and +2m ODN Net bed level Stour change over Area Planar area (m2) Volume (m3) Area (m) 1 -150 184,930 0.048 2 -9,410 -54,670 -0.031 3 8550 -59,580 -0.019 4 -1,381 31,537 0.048 5 -5,760 -46,220 -0.033 6 -2,678 7,043 0.014 7 1,160 27,400 0.013

Table 8 demonstrates that in Area 1, the Upper Stour, there has been only a very small change in the intertidal area between -1m ODN and +2m ODN between 2005 and 2010. This is because, in this area, nearly all of the bed is above -1m ODN. In other areas relatively small changes in intertidal areas have occurred over the analysis period. In Areas 1 and 4 (upper Stour and Bathside Bay) there has been a net accretion over the intertidal areas equivalent to 0.048m. In Areas 2 and 5 (Jaques Bay and Erwarton Bay) there has been a net erosion of the intertidal areas equivalent to about 0.032m.

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Bathymetric data

Bathymetric surveys have been undertaken of the Stour and Orwell up to a level of about +1.5 m CD to ensure adequate overlap with the LiDAR surveys and full level coverage of the estuaries. Following analysis of the initial results there were some technical difficulties in comparing the 2005 and 2010 surveys. The problems appeared to be focused on the 2010 bathymetry and could be caused by timing errors in the positioning system or unpredictable squat behaviour of the survey vessel.

The Orwell and a proportion of the Stour have been re-surveyed and the results are currently being analysed. More details will be available at the Regulators’ meeting (March 2011) and it is hoped that the analysis can be made on the repeated surveys and added to this report as an addendum. If it transpires that there are further problems with this data, the full survey may need to be re-run and included in the report for 2011.

3.3 Hamford Water

The bathymetric survey of Hamford Water was presented at the 2006 Regulators Meeting.

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4 BENTHIC MONITORING

Purpose: To record any actual impacts resulting from the dredging operation, disposal activities and mitigation measures on the health of the biological communities and to determine any changes in community type that could occur as a result of the above.

4.1 Stour and Orwell Estuaries

4.1.1 Annual benthic monitoring

The annual benthic monitoring programme is currently in its 4th year and is undertaken by Thomson UnicoMarine (Worsfold et al., 2011). This chapter discusses the data collected during the 2010 campaign. A detailed comparison of the data collected between 2008 and 2011 will appear in the 2011 compliance report, which will be produced in 2012.

The survey locations to which this data correlates are taken from those sampled in 1997 and 2003 as part of a wider sampling exercise. In 2007, it was decided that five year intervals between surveys make changes to the benthic environment difficult to interpret. Consequently, the annual monitoring approach was agreed (Steering Group 2007) with the emphasis on monitoring rather than on mapping. The survey sites (Figure 14) represent replicates within a selection of biotopes in each estuary or different parts of an estuary, to allow comparison between the benthos of like biotopes (UnicoMarine have prepared a description of biotopes linked to key species and sensitivities and this is provided as Appendix A).

Annual benthic data (plus benthic invertebrate biomass) will allow relationships between prey availability and bird numbers to be compared more easily and with a more robust data set to support any findings.

Methods

Groups of samples were selected to represent typical biotopes. Within each of those groups, four samples were taken, at positions that were sampled in both 1997 and 2003 (with 2 exceptions), to allow comparison between as many years as possible. There are four sample groups on the Orwell and seven on the Stour.

2 Two 0.04m Shipek grab samples were taken at each station; one for particle size analysis (PSA) and one for benthic biological analysis. Sampling points from the 2010 survey were plotted and numbers of taxa and individuals, total biomass, and cluster groups were plotted and biotopes extrapolated.

Results

Numbers of taxa were generally highest in the subtidal samples targeted as biotope SS.SMx.IMx.SpavSpAn (Sample Groups StF and OrC), which includes many fanworms (Sabella pavonina); 69 taxa were recorded at Station 189 (StF). The samples with the lowest numbers of taxa were also from subtidal habitats: StD and OrD, targeted as biotope SS.SMu.SMuVS.AphTubi; Station 296 (OrD) had only 6 taxa. Number of individuals were generally highest intertidally (StB) and lowest in the

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subtidal groups StD and OrD. Total biomass was higher both in intertidal upper Orwell samples (OrA) and subtidally, in one of the samples from the Stour (StF) and lowest subtidally at OrD. Mean biomass was highest in OrC and lowest in OrD. The taxa with the highest mean biomass for the survey as a whole were slipper limpets (Crepidula fornicata), fanworms (Sabella pavonina) and cockles (Cerastoderma edule).

4.1.2 Biotope descriptions

Annual benthic data and biotope descriptions are intended to facilitate the discussions/correlations on the relationships between prey availability and bird numbers along the Stour and Orwell estuaries.

The tables below (Table 9 and 10) represent the biotopes of the estuaries and how they may have changed from 2008 to 2010. The discussion below is a qualitative assessment of the information contained within the Benthic Report (Worsfold et al. 2010).

There has been little change in the species composition in the upper reaches of both estuaries (StA, StB, OrA, OrB) where the biotopes identified in 2008 can still be used to describe the sites in 2010 (see Table 10). These biotope classifications also correspond to the 2003 data upon which the biotopes were first identified. The middle and lower reaches (OrC, OrD, StC, StD, StE, StF, StG) are where the majority of the change has occurred although the changes do not seem significant.

Upper reaches

The upper reaches of the Stour (StA – LS.LMu.UEst.Hed) can be described as mud/sandy mud with the infauna dominated by harbour ragworms (Hediste diversicolor) and including other species such as Heterochaeta costata, Streblospio shrubolii, Manayunkia aestuarina and Hydrobia ulvae. Hediste diversicolor is an important bird feeding and bait species. Most of the other species are too small to be of interest to bait diggers but some birds specialise in preying on smaller worms and Hydrobia.

StB, OrA and OrB (LS.LMu.MEst.HedMac) have similar conditions to the previous biotope, where mud dominates the substrate and salinity varies between the fresher upper reaches and saline intrusion from the North Sea. Species composition is also similar with Hediste diversicolor present. Bivalves co-dominate this biotope with the most notable species being Macoma balthica. Lugworms, although not an indicator for this biotope, may also be present in these areas but are often missed by the current survey methodology. Hediste diversicolor is an important bird feeding and bait species. Many of the bivalves present in the biotope would also be important bird prey species and cockles may be fished commercially. Hydrobia also form an important prey species of some wading species. Site OrB had shifted slightly to the biotope LS.LMU.MEst.NhomMacStr in 2009, which is dominated by the small worm Streblospio shrubsolii. However, it should be noted that this biotope is only loosely distinguishable from LS.LMu.MEst.HedMac and therefore exhibits similar characteristics and species composition explaining the change in 2009 and 2010. The species Cerastoderma edule, a medium sized filter feeding bivalve, and Mya arenaria may be an important prey species for birds. Other bivalve species present in this biotope would also form an important component of the prey species of wading birds.

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Mid / Lower reaches

The mid/lower reaches of the Orwell estuary (OrC) can be characterised by muddy gravelly sand with pebbles (SS.SMx.IMx.SPavSpAn) and Sabella pavonina beds dominating the infauna assemblage in the subtidal zone. Sabella pavonina (Fanworm) is a large worm that builds muddy tubes attached to small stones or shells that are often buried in mud. The worms have crowns of tentacles that are extended for filter feeding. Sabelliphilus elongates is a very small crustacean that parasitises fanworms. However, some of the sites within this group have changed in 2009 and 2010. In 2009, the site shows characteristics of the biotope SS.SMu.SMuVS.NhomTubi. This biotope is characterised by the presence of catworms (Nephtys hombergii) and oligochaete worms such as Tubificoides amplicasatus. Although catworms are considered prey species for birds this site is subtidal and therefore this site cannot be seen as one that facilitates bird feeding directly. Some of the findings may be due to patchy distribution of habitats but further sampling and analysis of data will help to determine more meaningful trends.

Site OrD is a subtidal site with biotopes characteristic of mud or sandy mud in variable salinity. It is dominated by polychaetes including the catworm Nephtys mostly present as juveniles. The dominant biotope in this area has changed from SS.SMu.SMuVS.AphTubi to SS.SMu.SMuVSNhom.Tubi and LS.LMu.MEst.NhomMacStr which indicates a slight change in dominance of key polychaetes.

Within the intertidal zone in the Orwell the sites comprise two biotopes, namely LS.LMu.MEst.HedMac and LS.LMu.MEst.NhomMacStr both of which are dominated by prey species for birds.

In the Stour, the 2010 surveys suggest that most of the sites sampled linked to the biotope LS.LMu.MEst.HedMac with variety within the samples within many of the sites. Within the intertidal zone the sites are dominated, as in the Orwell, by LS.LMu.MEst.HedMac with LS.LMu.MEst.NhomMacStr in other areas throughout the middle and lower estuary. However, LS.LMu.UEst.Hed dominates the upper samples. The two dominant species from these biotopes are a good source of food for waders.

StD does not exhibit the same level of change and although it is present this area has been stable in 2008, 2009 and 2010 with Aphelochaeta marioni and Tubificoids spp in the subtidal zone and Macoma Balthica in the intertidal zone. In 2010 the site showed characteristics of the lower reaches site with the presence of Sabella pavonina.

There has been an apparent decrease in the biomass recorded for the survey sites in the upper reaches of the Stour Estuary in particular and the middle reaches of the Orwell Estuary which may be due to a number of reasons including habitat variability and changes to feeding densities of certain birds or changes to bait digging activities. Again, further data will help to inform trends in data linked to bird numbers within the count units.

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Figure 14 Location of sample sites on the Stour and Orwell Estuaries

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Table 9 Biotopes for the Orwell Estuary for the survey in 2008, 2009, 2010

OrA OrB OrC OrD 2008 LS.LMU.UEst.HedMac LS.LMu.MEst.HedMac SS.SMx.IMx.SpavSpAn; SS.SMu.SMuVS.AphTubi; SS.SMu.SMuVS.AphTubi SS.SMu.SMuVS.PolCval (25:75) (75:25) 2009 LS.LMU.UEst.HedMac LS.LMu.MEst.HedMac; SS.SMx.IMx.SpavSpAn; SS.SMu.SMuVS.NhomTubi; LS.LMu.MEst.NhomMacStr LS.LMU.MEst.NhomMacStr SS.SMu.SMuVS.PolCval; (50:50) (50:50) LS.LMu.MEst.NhomMacStr (25:25:50) 2010 LS.LMU.UEst.HedMac LS.LMu.MEst.HedMac; SS.SMx.IMx.SpavSpAn SS.SMu.SMuVS.NhomTubi; LS.LMu.MEst.NhomMacStr LS.LMu.MEst.NhomMacStr (75:25) (50:50) Key: LS – Littoral sediments; LMu – Littoral mud; UEst – Polychaete/oligochaete dominated upper estuarine mud shores; Hed – Hediste diversicolor in littoral mud; MEst – Polychaete/bivalve dominated mid estuarine mud shores; HedMac – Hediste deversicolor and Macoma balthica in littoral sandy mud; Nhom.MacStr – Nephtys hombergii, Macoma balthica and Streblospio shrubsolii in littoral sandy mud; SMx – Sublittoral mixed sediment; IMx – Infralittoral mixed sediment; SpavSPAn – Sabella pavonina with sponges and anemones on infralittoral mixed sediment; NhomTubi – Nephtys hombergii and Tubificoides spp. in variable salinity infralittoral soft mud; PolCvol – Polydora ciliate and Corophium volutator in variable salinity infralittoral firm mud or clay.

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Table 10 Biotopes for the Stour Estuary for the survey in 2008, 2009, 2010

StA StB StC StD StE StF StG 2008 LS.LMu.UEst.Hed LS.LMU.MEst.HedMac LS.LMU.UEst.HedMac; SS.SMu.SMuVS.AphTubi; LS.LMu.UEst.Hed; SS.SMx.IMx.SpavSpAn; LS.LMu.MEst.HedMac LS.LMu.UEst.Hed (75:25*) LS.LMu.MEst.HedMac (50:50) LS.LMU.MEst.HedMac (75:25) SS.SMu.SMuVS.AphTubi; SS.SCS.SCSVS (50:25:25) 2009 LS.LMu.UEst.Hed LS.LMU.MEst.HedMac LS.LMu.MEst.NhomMacStr; SS.SMu.SMuVS.AphTubi; LS.LMU.MEst.HedMac SS.SMx.IMx.SpavSpAn; LS.LMu.MEst.HedMac; LS.LMU.UEst.HedMac (75:25) LS.LMu.MEst.NhomMacStr (50:50) SS.SMu.SMuVS.AphTubi (75:25) LS.LMu.MEst.NhomMacStr (50:50) 2010 LS.LMu.UEst.Hed LS.LMU.MEst.HedMac LS.LMU.MEst.HedMac; SS.SMu.SMuVS.AphTubi; LS.LMU.MEst.HedMac SS.SMx.IMx.SpavSpAn; LS.LMu.MEst.HedMac; LS.LMu.MEst.NhomMacStr (75:25) LS.LMU.MEst.HedMac; SS.SMu.SMuVS.AphTubi (50:50) LS.LMu.MEst.NhomMacStr (50:50) SS.SMx.IMx.SpavSpAn (50:25:25) Key: LS – Littoral sediments; LMu – Littoral mud; UEst – Polychaete/oligochaete dominated upper estuarine mud shores; Hed – Hediste diversicolor in littoral mud; MEst – Polychaete/bivalve dominated mid estuarine mud shores; HedMac – Hediste deversicolor and Macoma balthica in littoral sandy mud; Nhom.MacStr – Nephtys hombergii, Macoma balthica and Streblospio shrubsolii in littoral sandy mud; SMx – Sublittoral mixed sediment; IMx – Infralittoral mixed sediment; SpavSPAn – Sabella pavonina with sponges and anemones on infralittoral mixed sediment; NhomTubi – Nephtys hombergii and Tubificoides spp. in variable salinity infralittoral soft mud; PolCvol – Polydora ciliate and Corophium volutator in variable salinity infralittoral firm mud or clay.

* Ratio assumes that each sample location represents 25% of the biotope

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4.2 Felixstowe South Reconfiguration Monitoring

The following is a summary from the full survey report (Finbow et al, 2011). Following an ecological assessment survey in 2003, a monitoring schedule was established for the Felixstowe South Reconfiguration (FSR), comprising six Shipek grab stations (each with three replicate macrofaunal samples and one PSA sample) and five 2-metre beam trawl samples (Figure 15). The first monitoring survey was completed in July 2008, with a second in 2009 and the third in 2010. Work had begun on the FSR by July 2009 and the July 2010 survey represents the second survey after some potential impact.

In all three years, the grab samples formed two main community types. One included Stations 32 and 41 (and, in 2008, Station 33), to the west of the channel in relatively deep water. The biota included typical infaunal species for the biotope SS.SMu.SMuVS.NhomTubi. The sediment was dominated by silt/clay in this community.

The other community included station 43 from the east side of the dredged channel and other stations (12 and 13 in all years; 33 in 2009 and 2010) on the Shelf. The infauna was typical of the biotope SS.SMu.SMuVS.AphTubi, which is here taken as the classification for the second community, as it appears to represent an infaunal component common to several biotopes in the area and to be the community most reliably recorded by Shipek grabs. Overlap with epifaunal biotopes is suggested by the presence of fanworms (Sabella pavonina) at Station 43 and ross (Sabellaria spinulosa) on the Shelf; these species characterise their own biotopes. The sediment in these samples was mixed.

The shift of Station 33 from SS.SMu.SMuVS.NhomTubi to SS.SMu.SMuVS.AphTubi between 2008 and 2009 has been the only significant change between the surveys to date; 2010 communities were as for 2009. The biological change observed was associated with a corresponding change in sediment type. It does not represent impoverishment and is unlikely to have been the result of development activity.

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Figure 15 Sample Locations - Felixstowe South Reconfiguration Monitoring

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4.3 Inner Gabbard East Disposal Site

The following is a summary from the full survey report (Pears and Worsfold, 2010). The Inner Gabbard East site was proposed as a disposal ground for dredged material from the Felixstowe South Reconfiguration (FSR) project as part of an Evironmental Impact Assessment in 2003. A biological survey was undertaken in summer 2002 prior to disposal, and disposal ended in June 2010. Three replicate biological samples were collected from nine stations, using a 0.1m² Hamon grab, along with PSA samples from each station.

The fauna found were typical for an area of mixed sediment at depths of 20-40m. SIMPROF cluster anaylysis identified 8 separate cluster groups, which were assigned to four biotopes. Several stations had replicates that clustered separately in SIMPROF analysis and communities were difficult to assign to standard biotopes. They were characterised by mixed substrata, dominated by infaunal polychaetes, with some Crustacea and varying epifaunal components.

The Stations within the disposal ground were dominated by Silt/Clay, which was also high at Stations just north of the disposal area. The samples taken within the disposal site also had a relatively reduced fauna, with lower numbers of taxa and individuals than the surrounding Stations and including two samples with no fauna at all. This reduced fauna is likely to result from the disposal of dredged material.

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5 TRIMLEY MARSHES MANAGED REALIGNMENT SITE

5.1 Background

The Trimley Managed Realignment Site is situated on the east bank of the Orwell Estuary, approximately two nautical miles upstream from Felixstowe. The site was successfully created in November 2000 as a condition in the Mitigation and Monitoring Package (MMMP) for obtaining the various permissions to carry out channel deepening to the Haven Ports.

The site consists of approximately 16.5ha of intertidal mudflat fringed with developing pioneer saltmarsh and represents 0.5% of the total Stour and Orwell Estuaries SPA designated area.

Maintenance dredgings (fine mud) from the channel in the lower Orwell Estuary were pumped into the site to provide a suitable substratum for colonisation of estuarine flora and fauna. The dredged material formed a layer approximately 30 to 50cm deep above the underlying soil and a series of mini-bunds were created throughout the site, to retain dredged material and allow access for surveying.

Under the MMP it was a requirement that 10 years worth of monitoring was undertaken at the site. The September 2010 survey marks the tenth year of monitoring and, therefore, the last survey and report to be produced for the site under the current MMP.

Twenty benthic and vegetation surveys have been completed, the dates of which are provided Table 11.

Table 11 Dates of the vegetation and macrofaunal surveys

Survey Date Survey Date number number 1 4th June 2001 11 16th March 2005

2 6th September 2001 12 6th September 2005

3 11th December 2001 13 5th April 2006

4 5th April 2002 14 26th September 2006

5 18th June 2002 15* 12th March 2007 *

6 11th October 2002 16 4th September 2007

7 25th April 2003 17 1st – 2nd April 2008

8 17th September 2003 18 8th – 9th September 2008

9 17th March 2004 19 9th-10th September 2009

10 21st October 2004 20 1st – 2nd September 2010 * Data is not available for the March 2007 survey as samples were mislaid during transportation between laboratories

This summary presents the results of monitoring in 2010 in combination with the data from all previous surveys. Full survey results and analysis are provided in the 2010 Annual Monitoring Report (Royal Haskoning, 2011a).

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5.2 Methodology

A hovercraft was used to navigate the site, from which benthic invertebrate and sediment samples were taken.

5.3 Results

5.3.1 Particle Size Analysis

The mean percentage contribution of silt and clay (i.e. particles <0.0625mm) to sediments from survey 1 (June 2001) to survey 20 (September 2010) is 95.7%. The sediment has coarsened since creation of the site, with sediments from the latest survey (survey 20) reported to be 90.3% silt and clay which is below the average but still representing a high proportion of fine sediments at the site.

In this study the particle size has been represented using Phi (), where the greater the Phi value, the smaller the diameter of the particle. Figure 16 indicates the mean phi for surveys from 13 to 20. Prior to survey 13 (April 2006) mean Phi values are not available due to a previously different analysis technique.

The graph indicates that whilst the sediment at the site is classified as silty, the Phi value has decreased indicating a slight coarsening of sediment. The Phi has fluctuated but the classification of sediment type has only changed from fine to medium silt between surveys 13 and 20.

Figure 16 Mean phi for Trimley samples for surveys 13 (April 2006) to 19 (September 2009)

7.20 Fine silt 7.00

6.80

6.60 Medium silt i

h 6.40 P

6.20

6.00 Coarse silt 5.80

5.60 13 14 16 17 18 19 20 Survey number

* Data is not available for the March 2007 survey (survey 15) as samples were mislaid during transportation between laboratories

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5.3.2 Benthic Community Analysis

Species Richness Species richness is the number of species present in a community and for this study it was enumerated by the mean number of species per core for each survey, averaged across the 12 sites.

Over the monitoring period, the mean number of species per core has generally increased despite some fluctuations. In survey 20 (September 2010) an average of 16 species per core was recorded, which is down from 18 in survey 19 (September 2009) however, much higher than the initial result of 6 species in survey 1.

Over all of the surveys, a total of 94 different taxa have been recorded since the site was created.

The starlet sea anemone Nematostella vectensis has been collected during surveys at the Trimley site since September 2007. This species is protected due to its limited distribution and vulnerability, and therefore, colonisation at the Trimley site is a notable achievement. In survey 20, 38 individual starlet sea anemones were collected from all of the cores across the site.

Abundance The abundance of each species was summarised by calculating total counts of individual invertebrates for each benthic core.

The numbers have been increasing overall since the site was created, but fluctuations can be seen from year to year much of which can be attributed to the presence of the mud snail Hydrobia ulvae (Figure 17). In survey 20 the decline in overall mean abundance was influenced more by the reduced numbers of other species, rather than the decline in Hydrobia ulvae.

Figure 17 Mean number of individuals of benthic macrofauna recorded per core for each survey between survey 1 (June 2001) and survey 20 (September 2010)

All taxa Hydrobia omitted Hydrobia

350

300 e r o c

r 250 e p

s l

a 200 u d i v i d n i

150 f o

o n

n 100 a e M 50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20 Survey number

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* Data is not available for the March 2007 survey (survey 15) as samples were mislaid during transportation between laboratories

Diversity Diversity is generally used as a measure to describe the structure and ‘health’ of a community and involves the consideration of two components: species richness and evenness. Species richness is the number of species present in the community while evenness is the degree of similarity of abundances between species.

The diversity of samples has fluctuated throughout the monitoring period. The presence of Hydrobia ulvae decreases the diversity at the site as it accounts for a large majority of the taxa present in the samples and influences the diversity index (Figure 18).

In survey 20 (September 2010) the diversity has declined as despite an overall decreasing abundance at the site the abundance of Hydrobia ulvae has exceeded the number of other species in the samples (see Figure 17). Diversity is, however, significantly greater than it was when the site was first monitored in survey 1 (June 2001).

Figure 18 Mean Shannon-Weiner diversity index (H’) for each survey between survey 1 (June 2001) and survey 20 (September 2010) Mean Shannon-Weiner diversity index All taxa Hydrobia omitted 2.5

2.0

1.5 ' H

1.0

0.5

0.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20 Survey number

Biomass Biomass (measured as weight of benthic invertebrates per core) can provide an important indicator of a habitat’s ability to support predators such as birds.

The biomass of benthic invertebrates has increased since the site creation in June 2001 as would be expected. The biomass of polychaetes present in the samples has remained low but constant throughout the surveys and molluscs have dominated the samples. There has been a steep decline in biomass in survey 20 (September 2010) (Figure 19). This latest decline in biomass is mostly due to decreased abundance of mollusca which is dominated by the mud snail Hydrobia ulvae. Numbers of Hydrobia

Annual Report 2010 9W1517 Final Report - 41 - March 2011

fluctuate over time but when there are declines in this species it shows a dramatic effect in the biomass as this species makes up a large proportion of the taxa.

Percentage contributions of each major group to the overall wet-weight biomass indicated that the percentage of polychaetes in the samples from survey 20 was up to 19.8% from 5.9% in survey 19 despite the actual weight of polychaetes remaining similar (around 5g per core). This is due to the reduced abundance of molluscs (primarily Hydrobia ulvae) resulting in the typical abundance of polychaetes providing a greater contribution to the overall site biomass.

Figure 19 Blotted wet-weight biomass (g) of polychaetes and molluscs in all samples between survey 1 (June 2001) and survey 20 (September 2010)

Polychaeta Mollusca Total 90

80 ) g (

y 70 e v r u s

60 r e p

t

h 50 g i e w - t

e 40 w

d e t t 30 o l b

l a t 20 o T

10

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20 Survey number

* Data is not available for the March 2007 survey (survey 15) as samples were mislaid during transportation between laboratories

Multivariate Analysis of Community Structure Multivariate analysis of the sample data was carried out using the PRIMER (Plymouth Routines in Multivariate Ecological Research) computer software package.

In order to compare the similarity of the faunal composition of different samples a Bray– Curtis similarity index was calculated. The results of this are presented in a multidimensional scaling (MDS) plot (Figure 20) which shows community assemblage grouped by survey. The transitional plot indicates that the first survey, labelled as survey 1, is located further away from the rest of the surveys representing the relative difference in community structure directly after recharge. From survey 2 onwards the points are in clusters and display a temporal transition as the site develops.

Annual Report 2010 9W1517 Final Report - 42 - March 2011

Figure 20 MDS Plot of Bray-Curtis similarity index for average of sites, over all surveys

* Data is not available for the March 2007 survey (survey 15) as samples were mislaid during transportation between laboratories

5.3.3 Vegetation

The vegetation at Trimley has been monitored since the first survey in 2001 and Plate 5 comprises photographs taken at the realignment site over the surveys to provide an indication of how the saltmarsh at Trimley has developed. The most extensive area of vegetative cover is in the north-western corner of the site. This area is well established and has the widest range of saltmarsh species compared to anywhere else in the site. The dominant species in this area are common glasswort Salicornia europea in the lower marsh, and clumps of grass-leaved orache Atriplex littoralis in the upper marsh with strips of cord grass Spartina anglica and occasional patches of saltmarsh grass Puccinellia maritima and sea lavender Limonium vulgare. Sparse clumps of seablite Suaeda maritima are also present.

During recent surveys the distribution of saltmarsh on site has been tracked using a hand held GPS. This data is available from survey 8 (September 2003) onwards. The percentage of saltmarsh coverage on site is shown in Table 12. The total area of the Trimley site is 16.5ha and one of the criteria for successful habitat creation at Trimley is that no more than 30% of the site should develop into saltmarsh. Although the saltmarsh is still developing and generally has expanded, it is not expected to reach 30% coverage due to height of the site in the tidal frame. The area of saltmarsh recorded in survey 20 was 3.37ha (20.4% of the site area), similar to survey 19.

Annual Report 2010 9W1517 Final Report - 43 - March 2011

Table 12 Saltmarsh development at the Trimley site for available surveys since survey 8 (September 2003). Total area of site is 16.5ha.

Survey Number and date Saltmarsh coverage

ha %

Survey 8 September 2003 1.67 10.12

Survey 10 October 2004 1.90 11.52

Survey 11 March 2005 1.70 10.30

Survey 15 March 2007 1.91 11.55

Survey 16 September 2007 2.00 12.00

Survey 17 April 2008 2.01 12.21

Survey 18 September 2008 2.19 13.27

Survey 19 September 2009 3.39 20.5

Survey 20 September 2010 3.37 20.4

5.3.4 Waterfowl

The latest waterfowl counts are taken from the 2009/10 low water data counted by the Suffolk Wildlife Trust (SWT, 2010). The Trimley site is represented by count sector 31 in the Orwell Estuary. It is recognised that many species use the site at different times of the tidal cycle and that the bird numbers recorded are just for the low water times.

Since 2000/01, a total of 24 species have been recorded on the site (excluding gulls) over all of the surveys. In 2009/10, there were 11 species recorded, all of which had been observed on site previously.

Peak numbers of birds have increased at Trimley since the first survey in 2000/01, directly after creation. In the 2009/10 surveys there was an increase in peak numbers of all species from 287 in 2008/09 to 462. This is largely due to the substantial increase in the number of redshank and knot recorded. Mean total numbers have increased since 2008/09, and overall since the monitoring began in 2000/01 the mean has increased from 1 up to 181 birds in 2009/10.

Since the 2008/9 surveys, there has been an increase in the mean number of five of the species which qualify for international status, including black-tailed godwit, dunlin, grey plover, knot and redshank (Figure 21). The largest increase is in grey plover numbers which has increased from 2 individuals in 2008/09 up to 11 individuals in 2009/10. This is the largest mean number of grey plover recorded since the monitoring began in 2000/01.

Annual Report 2010 9W1517 Final Report - 44 - March 20112 002?

Sept 2008 April 2006 Sept 2010 Sept 2005 April 2008 April 2006

Sept 2008

Sept 2005 Sept 2008 South 2002?

June 2002

West

Sept 2010

Sept 2008

April 2002 East Trimley Managed Realignment Site North September 2008 saltmarsh distribution from 2001 to 2010 Sept 2010

Sept 2010 June 2002 September 2010

Plate 5 Saltmarsh development at Trimley Managed Realignment Site from 2001 to 2010

Trimley Managed Realignment Site February 2011 Annual Report 2009 - 45 - 9W1452

The mean number of knot recorded at Trimley in 2009/10 was 49 which is the second highest count of knot recorded during the 10 years after the large flock of knot were counted at the site in 2007/08 increasing the mean number to 251.

Black-tailed godwit have doubled in numbers from a mean of one individual in 2008/09 to two in 2009/10, but the numbers are still substantially lower than in 2005/06 when the mean was 11.

Redshank showed a substantial increase in 2009/10 to 88 from 45 recorded in 2008/9. Both the mean numbers and peak numbers recorded in 2009/10 are the highest since 2000/01.

Dunlin were not recorded during the 2008/09 surveys however were recorded during 2009/10 in low numbers. A mean of one dunlin was recorded with a peak of four (2009/10).

No Dark-bellied Brent goose were recorded between 2008/09 and 2009/10. The highest count of this species was recorded in 2001/02 when a mean of 7 birds (peak of 26) was recorded.

The majority of key species are increasing in number in 2009/10 there is no reason to think that the site is not functioning well as intertidal habitat for the waterfowl population.

Figure 21 SPA qualifying waterfowl mean numbers at Trimley Managed Realignment Site (sector 31), 2000/01 to 2009/10 (SWT, 2010)

Black-tailed godwit Dunlin Grey plover Redshank Brent goose Knot

250 1 3

200 r o t c e S

n

i 150

s r e b m

u 100 n

d r i b

n

a 50 e M

0 2000-2001 2001-2002 2002-2003 2003-2004 2004-2005 2005-2006 2006-2007 2007-2008 2008-2009 2009-2010 Winter

5.4 Conclusion

Over the ten years of monitoring, the Trimley site has become an established intertidal benthic community which supports a wide range of waterfowl and contributes to maintaining the integrity of the internationally designated sites.

Annual report 2010 9W1517 Final Report - 46 - March 2011

Saltmarsh at the site has thrived, and in line with the design criteria for Trimley, a diverse community has developed but is unlikely to exceed the 30% threshold for vegetative growth.

The period of monitoring as specified within the Mitigation and Monitoring Package is now complete and the ten years of monitoring has provided a clear indication of the development and successional changes within the site, a clear sign of the success of this habitat realignment site.

Future plans for the site will be discussed in consultation with the relevant stakeholders and authorities at the annual meeting in March 2011.

Annual report 2010 9W1517 Final Report - 47 - March 2011

6 TRINITY III HABITAT ENHANCEMENT MONITORING

6.1 Background

As part of the planning consent for the extension of Trinity III Terminal, HHA were granted a Food and Environment Protection Act 1985 (FEPA) licence in 2002 to beneficially dispose of dredged material through the construction of intertidal bunds on the foreshore at two sites along the River Orwell at Shotley and Trimley.

Monitoring of the sites commenced in November 2003 following the completion of the Shotley bunds on 26th September 2003 and the Trimley Bund in October 2003. Since then 15 surveys have been conducted.

The surveys comprise the collection of cores for biological and particle size analysis, and monitoring the development of the bunds and any vegetation with photographs and notes. A topographic survey is also undertaken by Wallingford Environmental Surveys Limited, and low water bird counts are taken by the Suffolk Wildlife Trust (SWT) as part of the Stour and Orwell Estuary counts.

The full results of the surveys with analysis and discussion is available in the 2010 annual report (Royal Haskoning, 2011b).

6.2 Methodology

Figure 22 illustrates the location of the sample stations for the Trimley and Shotley Habitat Enhancement Sites. The locations of the topographic transects are shown in Figure 23.

A hovercraft was used to navigate the site, from which benthic invertebrate and sediment samples were taken.

Annual report 2010 9W1517 Final Report - 48 - March 2011

Figure 22 Location of sample stations for Trimley and Shotley enhancement schemes

Trimley

Shotley

Annual report 2010 9W1517 Final Report - 49 - March 2011

Figure 23 Location of topographic transects for Trimley and Shotley

Area 4

Area 1

Area 2

Area 3

Annual report 2010 9W1517 Final Report - 50 - March 2011

6.3 Trimley Enhancement Scheme

6.3.1 Introduction

Since construction in 2003, the Trimley recharge site appears to have maintained its morphology with no obvious signs of erosion or accretion. Creeks continue to develop across the site which may affect erosion/accretion rates over time. Large patches of Enteromorpha have periodically colonised the site with no evidence of saltmarsh colonisation. The majority of the recharge site is between 0.0m and 0.2m above Ordnance Datum (Newlyn) (mODN), which means that the mudflat would be fully covered by water relatively low in the tidal frame and, therefore, the recharge site may be unsuitable for saltmarsh to develop.

6.3.2 Particle Size Analysis

The mean particle size distribution at the recharge sites is constant and the overall classification can still be defined as silt. The reference site has more varied particle size but the mean size is classified as silt.

6.3.3 Benthic Invertebrate Univariate Results

Species richness A range of invertebrate species has colonised the mudflats of the site and numbers of species have increased since recharge.

Directly after the recharge (November 2003), the number of species at the recharge sites was much lower than those at the reference sites, however, in the more recent surveys numbers have been generally the same between sites, occasionally higher at the recharge sites. Survey 15 (September 2010) showed an increase in numbers of species at two of the five recharge sites (a peak of 35 species was recorded at site 1) compared to survey 14 (September 2009). Declines were recorded at two sites and one site was unchanged. Six new species were recorded at the Trimley recharge sites in the most recent survey.

Abundance Species abundance at recharge site 1 dropped back to around 400 individuals in survey 15 (September 2010) following a large increase in survey 14 (September 2009). Numbers of individuals at sites 2-5 were all very low in survey 15. The reference site abundance remains generally similar to that at the recharge site, although there was a peak at reference site 13 in survey 15 (September 2010) of approximately 450 individuals, which is the highest recorded at a reference site to date and significantly higher than previous samples collected at site 13. Sample site locations are illustrated in Figure 22.

Diversity The Shannon-Weiner diversity index emphasises the species richness or equitability components of diversity to varying degrees. In survey 15 (September 2010) there was increased diversity at site 1 only, with sites 2-5 all showing a decrease. The results from Trimley reference site indicate a decrease in diversity across all reference sites in survey 14 (September 2009).

Annual report 2010 9W1517 Final Report - 51 - March 2011

Biomass Biomass (measured as weight of benthic invertebrates per core) can provide an important indicator of a habitat’s ability to support predators such as birds.

The biomass data is available only for survey 5 (June 2005) onwards as biomass analysis was not provided as part of the infauna analysis prior to this survey. Average biomass at the recharge sites fluctuates, but has been increasing since survey 12 (April 2008). The average biomass at the reference sites is more stable, an increase occurred in survey 14 (September 2009) but in survey 15 (September 2010) the reference site has returned to similar levels to those observed in survey 5 (June 2005).

Figure 24 indicates the percentage contribution of the major taxa to the samples taken from Trimley recharge and reference sites. Over the surveyed period, dominance at both the recharge and reference site has varied between molluscs and polychaetes. In survey 14 (September 2009), however, molluscs dominated the biomass at the recharge site. This alternating trend has continued in survey 15 (September 2010) with polychaetes dominating once more. The contributions of molluscs in this survey can be attributed mainly to Hydrobia ulvae and the polychaetes to Hediste diversicolor, Tubifoides pseudogaster and Streblospio shrubsolii.

The biomass composition at the reference site has remained relatively stable for the past four surveys with polychaetes dominating, followed by molluscs. The largest proportion of nemertea, nematoda and oligochaetes throughout all of the surveys were also recorded at the reference sites in survey 15 (September 2010).

Figure 24 Contribution of each major group to the overall observed blotted wet-weight biomass (g) of the samples at Trimley recharge (1-5) and reference (11-13) sites between survey 5 (June 2005) and survey 15 (September 2010) a) Trimley recharge site (1-5) Trimley recharge Nemertea Nematoda Polychaeta Oligochaeta Insecta Crustacea Mollusca Other taxa 100% 90% ) t 80% h g i

e 70% w

d

e 60% t t o l b

( 50%

s s

a 40% m o i 30% B

% 20% 10% 0% 5 6 7 8 9 10 11 12 13 14 15 Survey number

Annual report 2010 9W1517 Final Report - 52 - March 2011

b) Trimley reference site (11-13) Trimley reference

Nemertea Nematoda Polychaeta Oligochaeta Insecta Crustacea Mollusca Other taxa 100% )

t 80% h g i e w

d

e 60% t t o l b (

s s

a 40% m o i B

% 20%

0% 5 6 7 8 9 10 11 12 13 14 15 Survey number

6.3.4 Benthic Invertebrate Multivariate Results

Multivariate analysis of the sample data was carried out using the PRIMER (Plymouth Routines in Multivariate Ecological Research) computer software package.

MDS ordination plots indicate that the community composition at the reference site varies from survey to survey. It also suggests that in the first years of survey, the recharge site composition was somewhat different to that at the reference site, but over time the recharge sites have developed and the community has stabilised. Full details of the MDS plots are available in the 2010 report (Royal Haskoning, 2011b).

SIMPER was used to further analyse the samples. For Trimley recharge sites, the analysis indicates that the community structure between the samples has become more similar with time with 15.55% similarity in the first survey (November 2003) and 53.06% similarity in the most recent survey (September 2010). The Trimley reference sites, however, indicate that the community structure is unstable. The similarity of the samples has actually decreased since survey 1 from 69.69% to 45.64% in survey 15 (September 2010).

6.3.5 Topography

The topography survey has investigated the shape of the bund and how it has changed through time.

The latest plots from the 2010 survey appear to show that the crest of the offshore bund is continuing to slowly migrate inshore and build in height trapping/protecting the deposited mud behind it. The migration to date appears very gradual and is of little concern.

Annual report 2010 9W1517 Final Report - 53 - March 2011

6.3.6 Vegetation

No evidence of saltmarsh colonisation was observed during the most recent surveys. Creeks within the mud have continued to develop over time but no vegetation has grown in these areas. The mudflat is highly unlikely to ever be colonised with vegetation as it is some 1.5m to 2m below the optimum level for saltmarsh plants to establish (WES, 2009). However, remnant saltmarsh to the south of the site (characterised by the cord grass Spartina sp. and desiccated glasswort, Salicornia sp.) is present at an elevation approximately 0.5m above the recharge site. Gutweed Enteromorpha intestinalis was widespread across the mudflats in survey 14 (September 2009) but had cleared from the site in survey 15 (September 2010).

The filamentous green algae that was present at Trimley during survey 14 (September 2009) has all but gone on the mudflats, although the seaweed growth on the gravel banks is still present. There is, however, still evidence that the retained mudflat has continued to be colonised with marine invertebrates (worm casts and snail tracks visible) and wading birds are using the area (feeding dunlin and turnstone were observed during the survey visit together with numerous footprint tracks), hence the area has developed naturally and is serving its intended purpose.

6.3.7 Waterfowl

The total peak numbers of individuals at the Trimley site decreased directly after recharge in 2003, however, numbers have steadily increased since. The latest survey data (2009/10) shows the total peak number of individuals at the site to be 167 which is slightly lower than in 2009 but maintains a general trend upwards of peak numbers (Figure 25). The peak numbers still, however, remain much lower than the recorded numbers in 2000 to 2003, prior to the construction of the bunds in 2003/04.

The 2009/10 over-wintering counts indicate a continuing absence of dunlin and a decrease in mean numbers of turnstone. Great crested grebe numbers have remained low. Ringed plover, grey plover and oystercatcher have increased with redshank numbers having increased the most. .

It should be noted, however, that pre-construction mean numbers of all key species were no greater than 20 individuals and peak numbers with the exception of dunlin were also below 25.

Annual report 2010 9W1517 Final Report - 54 - March 2011

Figure 25 Mean and peak waterfowl abundance at Trimley Recharge Site (sector 10) counted at low water, 2000/01 to 2009/10 (SWT, 2010)

Mean Peak

400

350 s l a

u 300 d i v i d

n 250 I

f o

r 200 e b

m 150 u N

n 100 a e

M 50

0 2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

*Note; dotted line represent the construction of the bund in 2003

6.4 Shotley Enhancement Scheme

6.4.1 Introduction

The recharge sites appear to show an improving community structure, in terms of species richness, abundance and diversity, relative to the reference sites, although communities have begun to stabilise after an initial boom. At the southern recharge and reference sites, drainage was noted to be variable, with large areas of ponded water.

6.4.2 Particle Size Analysis

The sediment at north Shotley has been classified as silt throughout almost all of the surveys (the only exception being March 2005 when the classification changed to very fine sand). The location of the sample sites is shown in Figure 22.

At the mid Shotley recharge sites the samples taken for both sites 6 and 7 recorded a significant coarsening of the particles in survey 15 (September 2010). The mean sediment classification therefore changed to gravel. At the mid Shotley reference sites the mean Phi has dipped slightly from survey 14 (September 2009) but remains firmly within the silt fraction.

In survey 15 (September 2010) at south Shotley recharge, site 15 remained similar in particle size to survey 14 (September 2009) (in the gravel classification), and site 16 continued to become coarser. The particle size at the reference site has become coarser making the recharge and reference sites now much closer in particle size, although the recharge site remains in the gravel classification and the reference site in the sand classification

Annual report 2010 9W1517 Final Report - 55 - March 2011

6.4.3 Benthic Invertebrate Univariate Results

Species richness Overall, despite fluctuations, species richness has increased at all Shotley sites since monitoring began. At north Shotley (site 9) species richness decreased in survey 15 (September 2010) to 10 species from the peak of 26 in survey 14 (September 2009). At the mid Shotley recharge sites species richness has increased at both sites to a peak of 26 at site 7, and 23 at site 6. There were 7 taxa recorded which were new to the north and mid Shotley recharge sites in survey 15. Species richness at the mid Shotley reference sites decreased in survey 15 to similar numbers recorded at the north Shotley site.

The south Shotley species richness is generally increasing at both the recharge and reference sites. Site 16 recorded a peak of 34 species in survey 15 (September 2010). Overall species richness at the south Shotley reference site remains greater than that at the recharge sites but the gap between the two is reducing with each survey year.

Abundance The abundance at north Shotley has decreased significantly in survey 15 (September 2010) to less than 20 individuals from 178 in survey 14. Mid Shotley sites (6 and 7) both increased in survey 15, but site 6 recorded a massive rise from 7 (survey 14) to 350 individuals in survey 15. This increase at site 6 can be attributed to a large number of the polychaete worm Ophelia rathkei.

Abundance at the reference sites (8 and 10) is typically lower than the recharge sites, although peaks were recorded in survey 12 and survey 13 at sites 8 and 10 respectively which were uncharacteristic. In survey 15 (September 2010), the abundance at both reference sites was below 20. North Shotley (site 9) still appears to be more similar to the reference sites, all of which are located north of mid Shotley sites 6 and 7

South Shotley recharge sites have both increased in abundance in survey 15 (September 2010). More individuals were recorded at site 15 than site 16, but both sites showed higher abundance than the south Shotley reference site (14) which declined slightly in numbers in survey 15. Locations of each of the sites are shown in Figure 22.

Diversity The species diversity at north Shotley recharge (site 9) has supported a relatively consistent diversity of species throughout the surveys. Diversity is higher at site 7 in survey 15 (September 2010) than at the other mid Shotley site (site 6) and north Shotley. Survey 15 indicated similar diversity at both reference sites, around the same diversity as the north Shotley site but lower than site 7.

The analyses of survey 15 (September 2010) data on south Shotley recharge sites indicate no change in diversity at site 15 compared to survey 14 (September 2009) and a peak of diversity at site 16. Diversity is now very similar at the reference site and the recharge sites in survey 15 (September 2010). Diversity has generally increased at the reference site since survey 9 (September 2006) in line with the increase in species richness.

Annual report 2010 9W1517 Final Report - 56 - March 2011

6.4.4 Biomass

The biomass of the invertebrate communities was analysed to determine the overall wet-weight of benthic invertebrates and the percentage composition of major taxa in the samples. The taxa were typically described as phyla, although polychaetes and oligochaetes were recorded separately.

The biomass at north and mid Shotley recharge sites is low compared to those at the south Shotley sites, although biomass at south Shotley has declined. Polychaetes dominate the biomass composition at the north and mid Shotley recharge and reference sites, whereas the south Shotley recharge sites are dominated by polychaetes, crustacea and molluscs. The biomass at the south Shotley reference site is almost entirely composed of molluscs in survey 15 (September 2010) although abundance at the site is low and only a few individual mollusc species were present, such as common cockle Cerastoderma edule, common mussel Mytilus edulis, grey chiton Lepidochitona cinerea, American paddock Petricola pholadiformis, and the manilla carpet shell Tapes philippinarum. The biomass at south Shotley recharge and reference sites is illustrated in Figure 26.

Figure 26 Contribution of each major group to the overall observed blotted wet-weight biomass (g) of the samples at south Shotley recharge sites (15&16) and reference site (14) between survey 5 (June 2003) and survey 15 (September 2010)

a) South Shotley recharge sites (15&16) Nemertea Nematoda Polychaeta Oligochaeta Insecta Crustacea Mollusca Other taxa 100% )

t 80% h g i e w

d

e 60% t t o l b (

s s

a 40% m o i B

% 20%

0% 5 6 7 8 9 10 11 12 13 14 15 Survey number

Annual report 2010 9W1517 Final Report - 57 - March 2011

b) South Shotley reference site (14) Nemertea Nematoda Polychaeta Oligochaeta Insecta Crustacea Mollusca Other taxa 100% )

t 80% h g i e w

d

e 60% t t o l b (

s s

a 40% m o i B

% 20%

0% 5 6 7 8 9 10 11 12 13 14 15 Survey number

6.4.5 Benthic Invertebrate Multivariate Results

The MDS ordination for North and Mid Shotley recharge and reference sites indicate that the benthic invertebrate communities at mid and south Shotley recharge sites have displayed a temporal shift over the surveys.

North Shotley recharge shows less of a temporal shift on the MDS plot and is more comparable to the reference sites, which are typically more varied in community composition between sites and across the surveys.

6.4.6 Shotley topographical results

North Shotley sites are represented in Area 4 (sites S10 and S16) (Figure 23). Sites S10 and S16 appear to remain relatively stable (Figure 27).

Annual report 2010 9W1517 Final Report - 58 - March 2011

Figure 27 Topographic composition of Area 4 (north Shotley) sites S10 and S16 a) North Shotley site S10 2nd Sept03 30thSept03 1st Sept04 20thSept05 13th Sept07 2nd Sept08 22nd August09 8thSept10

Elevation (mODN) 4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

-0.5

-1.0 200 210 220 230 240 250 260 270 280 290 300 310 Chainage (m) b) North Shotley site S16 2ndSept03 30thSept03 1stSept04 20thSept05 13thSept07 2nd Sept08 22nd August09 8th Sept10

Elevation (mODN) 4.0

3.5

3.0 2.5 2.0

1.5

1.0 0.5

0.0 -0.5

-1.0

-1.5 -2.0 190 200 210 220 230 240 250 260 270 280 290 300 310 Chainage (m)

At mid Shotley (Area 1) saltmarsh growth has been encouraged behind the bund since the ‘topping-up’. The crest of the bund is slowly migrating inshore in some sections covering the settling mudflats. It was evident that this year many more plants had colonised the bank crest (above the high water mark) binding the sandy gravel material and reducing the crest’s progress.

In Area 2 the grassed gravel/sand crest has remained at the same place but ‘overtopping’ sand has migrated some 6-7m westwards at section A2 smothering the mature saltmarsh plants

Area 3 incorporates sites around the marina, T1, T2 and T3. Its exposed position meant that soon after its completion it succumbed to the effect of wave action from winter

Annual report 2010 9W1517 Final Report - 59 - March 2011

storms. This area appears to have changed little from the 2009 survey where it was reported that the twin bund crests (upper and lower areas) had been ‘smoothed out’ to such an extent that the two areas appeared as one.

6.4.7 Vegetation

The saltmarsh development is most prominent on the mid-Shotley recharge sites (6 and 7). Since the ‘topping-up’ in this area behind the old bund in September 2003, saltmarsh vegetation has flourished and has colonised all but the most northerly area where water drains back into the River Orwell. Common glasswort Salicornia europea and cord grass Spartina anglica have become well established in this area. Plants have also started to colonise the banks crest above the high water mark. Areas of saltmarsh have also become established to the south along the coast.

Plant colonisation in the southern bunds (recharge sites 15 and 16) has been limited to Enteromorpha sp. with a few patches of knotted wrack Ascophyllum nodosum. Seaweed species have become established within this area.

One of the objectives for the enhancement scheme was to create 3ha of saltmarsh habitat across the sites. The majority of the saltmarsh growth is around the mid to north Shotley sites, and although measurements of saltmarsh area are not made at this site, the target of 3ha is unlikely to have been reached currently.

6.4.8 Waterfowl

Bird numbers have shown a general decline since the construction of the bunds in 2003. There was a low of 819 total peak bird numbers at Shotley in 2005/06, however, this has increased in subsequent years and was recorded to be 1079 in the most recent survey in 2009/10 (Figure 28).

Peak and mean numbers for selected key species observed at the Shotley site fluctuate between years, with increased numbers of lapwing, dark-bellied Brent goose and dunlin in the survey following the construction, but with declines in dunlin and lapwing numbers in recent years. For the 2009/10 survey dunlin and lapwing have both increased again, whereas Brent goose numbers have fallen sharply and wigeon show a slight decrease in numbers.

The mean numbers for lapwing, dunlin and dark-bellied Brent goose have fluctuated throughout the surveys and the high number of potentially influencing environmental variables makes it difficult to attribute any cause to these fluctuations.

Annual report 2010 9W1517 Final Report - 60 - March 2011

Figure 28 Mean and peak waterfowl abundance at Shotley Recharge Site (sector 30) counted at low water, 2000/01 to 2009/10 (Suffolk Wildlife Trust, 2010)

Mean Peak

2500

2000 s l a u d i

v 1500 i d n I

f o

r

e 1000 b m u N

500

0 2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

*Note; dotted line represent the construction of the bund in 2003

6.5 Conclusion

The Trimley and Shotley Habitat Enhancement Sites were established in 2003 and have been monitored every year since. The recharge sites on both sides of the estuary are fully functioning habitats which support a variety of benthic infauna and contribute to SPA designated habitat for over-wintering birds at low tide.

Although some of the recharge material may have eroded on the Shotley side, the habitat enhancement sites are achieving the objectives set out in the CMMP of providing intertidal feeding habitat, and increasing the exposure of the area for longer in the tidal cycle (particularly at Trimley).

Further monitoring will continue until 2012 when the ten years of monitoring will be complete and more long-term objectives for the site may be established.

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7 SUSPENDED SEDIMENT CONCENTRATIONS

Purpose: To meet the objective of providing sediment budgets that will enable refinement of mitigating/compensating measures, if required. To ensure that turbidity levels stay within acceptable limits following ongoing dredging and sediment reintroduction activities.

7.1 Monitoring Results

No further silt monitoring has been undertaken over the last year. Results have been presented in past annual reports.

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8 BIRD DISTRIBUTION AND ABUNDANCE

Purpose: To measure the position of the Stour and Orwell Estuaries SPA relative to regional and national trends for the designated species.

8.1 Background

The Stour and Orwell Estuaries are comprised of a range of habitats such as extensive mudflats, low cliffs, saltmarsh and small areas of vegetated shingle, making them a wetland of major international importance. The estuaries provide over-wintering habitat for a number of wildfowl and wader species. The estuaries are designated as a Special Protection Area (SPA) and Ramsar site due to the presence of these wintering waterfowl populations. When first designated in 1992, the SPA was known to regularly support over 20,000 waterfowl and populations of a number of species which were considered to be of national or international importance1.

Surveys on the over-wintering bird populations on the Estuaries are undertaken as part of the monitoring program to assess the effects of deepening the approach channel to the Felixstowe and Harwich ports.

High water counts are the primary focus of this report and are gathered as part of the Wetland Bird Survey (WeBS)2. The scheme has a long-running data set, with the most recent information available for surveys undertaken in 2008/09.

Low water counts are also undertaken as part of the WeBS scheme, but only at larger estuaries and on an infrequent basis, approximately one winter every six years. Therefore, to ensure there is a full data set which is comparable to the high water counts, low water counts for the Stour and Orwell Estuaries are undertaken, for Harwich Haven Authority, by the Suffolk Wildlife Trust (SWT).

The results of both the high and low water counts provide a good basis for summarising bird usage of the Stour and Orwell Estuaries. This section discusses all of the current bird data for the Estuaries available from recent reports, the WeBS Alerts (BTO, 2010a), the high water counts (Calbrade et al, 2010) and low water counts (SWT, 2010).

8.2 High water count trends

High water data from WeBS is available up to 2008/09 (Calbrade et al, 2010), however, it should be noted that WeBS Alert data is for the winter period in 2007/08). The total numbers of waterfowl over the winter periods from 1999/00 to 2008/09 are compared between the Stour and Orwell Estuaries in Figure 29 below.

The trend lines for these two estuaries, which are geographically very close, have typically counterbalanced each other. Where bird numbers decreased in the Stour Estuary, numbers generally increased in the Orwell. The Stour Estuary continuously

1 To be classified as being of national or international importance, over 1% of the Great Britain and East Atlantic populations respectively, must be present, 2 WeBS is a scheme run by the British Trust for Ornithology, The Wildfowl & Wetlands Trust, the Royal Society for the Protection of Birds and the Joint Nature Conservation Committee

Annual report 2010 9W1517 Final Report - 63 - March 2011

attracts a higher proportion of the SPAs over-wintering waterfowl. However, there have been some fluctuations in number, as can be seen from the period between 2001 and 2004. The total number of birds visiting the Orwell Estuary has been relatively stable since 1999/00.

Figure 29 Total number of waterbirds on the Stour and Orwell Estuaries (1999/00 data WeBS Annual Report 2003/04 Collier et al, 2005; 2000/01-2001/02 data WeBS Annual Report 2004/05 Banks et al, 2006; 2002/03–2006/07 data WeBS Annual Report 2006/07 Austin et al, 2008, 2007/08-2008/09 data WeBS Annual Report Calbrade et al, 2010 )

Orwell Estuary Stour Estuary

70000

60000

50000 s d r i b r

e 40000 t a w

f o

30000

r e b m u 20000 n

l a t o

T 10000

0

1999/2000 2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09

Winter

8.2.1 Weather conditions in eastern England

Over-wintering bird numbers can be significantly impacted by weather conditions. For example, when intertidal areas freeze over, estuarine birds are unable to feed and have to move to find alternative feeding areas. During hard weather, large scale bird movement is known to occur. During extremes of weather estuaries may act as refuges for migrating bird populations. A sudden increase in numbers in a UK estuary may reflect this movement of birds from the continent.

Meteorological Office weather data is recorded in the every WeBS annual report. In 2008/09 the winter weather around the Stour and Orwell Estuaries was reported to have been relatively settled with very cold periods in December and January. This period of cold weather may be a partial explanation for the increase in numbers seen in 2008/09. The weather patterns of 2009/10 and 2010/11 are anticipated to have been similar to the 2008/09 events with freezing conditions occurring during the winters of 2009/10 and 2010/11.

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8.2.2 WeBS Alerts

The WeBS Alerts system was developed to provide a standardised method of identifying the direction and magnitude of changes in bird population numbers. Species that have undergone significant changes in numbers can then be flagged by issuing an Alert (BTO, 2011a). The Alerts are then reviewed every three years and therefore the last evaluation period for the Stour and Orwell Estuaries was 2007/08. The Alerts will be reviewed following the processing of 2010/11 data.

Of the species evaluated at the Stour and Orwell SPA, 12 species have had alerts triggered (Table 13). High Alerts have been triggered for four species; cormorant, lapwing, dunlin and black-tailed godwit. Great crested grebe and ringed plover were previously recorded as High Alert species in 2004/05 but have now been reduced to Medium Alert. Other Medium Alert species include goldeneye, grey plover, redshank, shelduck, wigeon and pintail. Dark-bellied brent goose was previously on Alert status but has since been reduced, indicating that numbers have increased.

Over the long-term, one species (cormorant) shows a high alert and dunlin shows a medium alert. The rest of the species show either no change or a medium or high increase. Dunlin and back-tailed godwit show high level alerts were triggered in the medium term. Of the remaining species, 7 show a medium level alert in the medium term. In the short-term five species triggered medium alert, two of which are species known to have natural fluctuations in numbers.

Table 11 Wetland Bird Survey Alerts for the Stour and Orwell SPA (to winter 2007/08 inclusive) (BTO, 2011a)

Alert status for SPA suite GB Alert status for Stour and Orwell SPA Short Medium Long Short Medium Long Since Species term term term term term term designation (5yr) (10yr) (25yr) (5yr) (10yr) (25yr) 1994 Dark bellied o o + o o ++ o Brent Goose Shelduck o o o o - o - Wigeon o o + o o + - Pintail o o o o (-) (+) (-) Goldeneye o - o - - + - Great Crested o o + o - + - Grebe Cormorant o o + (-) - -- - Oystercatcher o o o o o ++ o Ringed o - o (+) o o - Plover Grey Plover o - + - - ++ - Lapwing o o ++ o - ++ -- Knot o o o o + ++ + Dunlin o - - (-) -- - -- Black Tailed o + ++ - -- ++ - Godwit Curlew o o + o o + o

Annual report 2010 9W1517 Final Report - 65 - March 2011

Alert status for SPA suite GB Alert status for Stour and Orwell SPA Short Medium Long Short Medium Long Since Species term term term term term term designation (5yr) (10yr) (25yr) (5yr) (10yr) (25yr) 1994 Redshank o o o o - o - Turnstone o o o o o + o * Symbols: - medium Alert, --high Alert, + medium increase, ++ high increase, o No substantial change, ( ) indicate species prone to natural fluctuations in numbers.

8.3 Low water trends

8.3.1 Suffolk Wildlife Trust report results

The trends in mean and peak numbers of principal species recorded during the low water counts are outlined below in Table 14. The trends identified are based on simple correlations and the key for probabilities, shown in the table below, reflects the confidence in the analysis of the trend and not the strength of the trend. More detailed species accounts taken from the low water count report (SWT, 2010) are available in Appendix B.

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Table 14 Trends in the mean and peak numbers of species on the Orwell, Stour and SPA 1999/00 to 2009/10 (SWT, 2010)

Colour Probability

Weak decrease in trend (- P = 0.05-0.099)

Weak increase in trend

(+ P = 0.05-0.099)

Strong decrease in trend

(- P = 0.01-0.05)

Strong increase in trend

(+ P = 0.01-0.05)

Very strong decrease in trend

(- P = 0.001-0.01)

Very strong increase in trend

(+ P = 0.001-0.01)

Species Mean Numbers Peak Numbers Orwell Stour SPA Orwell Stour SPA Brent goose Shelduck Wigeon Pintail Oystercatcher Ringed plover Grey plover Lapwing Knot Dunlin Black-tailed godwit Curlew Redshank Turnstone

Mean numbers of pintail, redshank and ringed plover, and peak numbers of pintail, black-tailed godwit, ringed plover and redshank have declined in the SPA from 1999/2000 to 2009/10. However, over the same period, mean numbers of knot and dunlin have increased. Within the individual estuaries, mean numbers of wigeon, turnstone and dunlin have increased in the Stour and mean numbers of pintail, black- tailed godwit and redshank have declined, whereas shelduck, knot and black-tailed godwit have shown an increase in mean numbers on the Orwell and wigeon, ringed plover and dunlin have decreased.

Annual report 2010 9W1517 Final Report - 67 - March 2011

Some changes in distribution of species are clear within the SPA but these assessments are subjective and analysis of changes in the distribution of species is required from the data. Pintail showed change in distribution, with birds almost exclusively using Trimley Marshes. Also, this species had moved from being spread out at Copperas, Holbrook and Seafield Bay on the Stour to being predominantly located along the Mistley foreshore. Other bird species, including ringed plover and grey plover have also shown a reduction in their distribution along the estuaries and have become more focused on key areas of the estuary, in particular Pond and Black Oozes on the Orwell and the Holbrook, Jacques and Bathside Bays on the Stour.

8.4 Bird abundance and usage of count sectors

Bird distributions along the Stour and Orwell estuaries have been compared for four species on low water data from 2001/02 to 2009/10 to provide an indication of bird movements and usage of areas of the estuaries. The species studied were shelduck, dunlin, black-tailed godwit and redshank, as these have been previously identified as species of interest on the estuaries.

The following sections outline bird numbers for the sectors identified in Figure 30.

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Figure 30 Low water count sectors

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8.4.1 Orwell Estuary

Shelduck

Shelduck distribution appears to be focused on key sectors within the estuary with minimal yearly variation (Figure 35). Since 2001/02 there has been some decline in Sectors 31 and 30, which are within the lower estuary area with increases in sectors 11 and 33, also in the lower estuary. Figure 35 also indicates that there is a lot of variation in shelduck numbers between the year counts. Bird numbers in different sectors vary on a year by year basis. Figure 3.1 indicates that bird numbers are fairly consistent between the three different sections of the estuary, with the mid estuary area showing an increase in numbers since 2004/05. Also the graph indicates that the lower and upper estuary areas have similar patterns, with numbers in the lower estuary increasing as upper estuary numbers decrease.

Figure 31 Mean Number of Shelduck on the Orwell between 2001 and 2010

Shelduck on the Orwell

800

700

600

500 Lower Estuary 400 Mid Estuary Upper Estuary 300

200

100

0 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

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Dunlin

Dunlin occurs throughout the whole estuary. Figure 32 below indicates that since 2005/06 numbers in the lower estuary area have declined within an increase in 2007/08, which matches a decline in numbers in the lower estuary. These bird numbers indicate that dunlin rely on the upper and mid sections of the estuary over the lower section, for prey species and shelter.

Figure 36 indicates that dunlin numbers are located to key sectors within the estuary. Since 2003/04 numbers appeared to have declined in Sector 17 (upper estuary), although numbers are showing a slight increase since 2007/08. Numbers have also shown a decline in Sector 41 (adjacent to sector 17 but in the mid estuary) since 2004/05.

Dunlin is known to feed on mollusc species, particularly Hydrobia and Macoma and polychaetes, such as Hediste and Nephtys.

Figure 32 Number of Dunlin on the Orwell between 2001 and 2010

Dunlin on the Orwell

2500

2000

1500 Lower Estuary Mid Estuary Upper Estuary 1000

500

0 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

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Black-tailed godwit

Black tailed godwit numbers fluctuate across the whole estuary area, with predominantly higher numbers being located on the lower and mid estuary areas. Numbers have increased in the mid estuary since 2001/02, with a peak number in 2005/06, followed by a decline in 2006/07 (Figure 33) and then a subsequent rise. Numbers were highest in the upper region of the estuary in 2007/08 and 2009/10 has shown a large increase in numbers for the lower region.

Black-tailed godwit numbers have remained fairly consistent (Figure 37) across Sectors. In Sector 5 (upper estuary), numbers declined from 2001/02, before increasing steadily to a peak count in 2007/08 followed by another decline from 2008/09 onwards.

Figure 33 Number of Black-tailed godwit on the Orwell between 2001 and 2010

Black-tailed godwit on the Orwell

900

800

700

600

500 Lower Estuary Mid Estuary 400 Upper Estuary

300

200

100

0 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

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Redshank

Redshank, like most of the bird species on the estuary, are located in higher numbers on the lower and mid estuary areas (Figure 34). All estuary areas have shown an increase in numbers since 2008/09. The mid estuary typically supports higher numbers of redshank, with a large amount of variation in numbers on the lower estuary.

Numbers of redshank within the mid estuary area were typically higher in the early years of survey than currently (Figure 38). However, numbers have not changed that dramatically.

Redshank feed on similar prey species to dunlin.

Figure 34 Number of Redshank on the Orwell between 2001 and 2010

Redshank on the Orwell

1000

900

800

700

600 Lower Estuary 500 Mid Estuary Upper Estuary 400

300

200

100

0 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

Annual report 2010 9W1517 Final Report - 73 - March 2011

Figure 35 Number of Shelduck on the Orwell per sector between 2001 and 2010

Shelduck on the Orwell

180 160 2001 - 2002 s

l 140

a 2002 - 2003 u d

i 120 2003 - 2004 v i

d 2004 - 2005

n 100 I

f 2005 - 2006 o

. 80

o 2006 - 2007 N

n 60 2007 - 2008 a e 2008 - 2009

M 40 2009 - 2010 20

0 01 02 21 03 18 17 22 23 05 41 40 06 39 38 19 24 37 26 35 25 36 11 27 12 28 31 32 29 33 10 30 34 Sector

Annual Report 2010 9W1517 Final Report - 74 - March 2011

Figure 36 Number of Dunlin on the Orwell per sector between 2001 and 2010

Dunlin on the Orwell

1000 900 2001 - 2002

s 800 l

a 2002 - 2003 u 700 d

i 2003 - 2004 v i

d 600 2004 - 2005 n I

f 500 2005 - 2006 o

.

o 400 2006 - 2007 N

n 2007 - 2008

a 300 e 2008 - 2009 M 200 2009 - 2010 100 0 01 02 21 03 18 17 22 23 05 41 40 06 39 38 19 24 37 26 35 25 36 11 27 12 28 31 32 29 33 10 30 34 Sector

Annual Report 2010 9W1517 Final Report - 75 - March 2011

Figure 37 Number of Black-tailed godwit on the Orwell per sector between 2001 and 2010

Black-tailed godwit on the Orwell

250

2001 - 2002 200 s l

a 2002 - 2003 u d

i 2003 - 2004 v i 150 d 2004 - 2005 n I

f 2005 - 2006 o

.

o 100 2006 - 2007 N

n 2007 - 2008 a e 2008 - 2009 M 50 2009 - 2010

0 01 02 21 03 18 17 22 23 05 41 40 06 39 38 19 24 37 26 35 25 36 11 27 12 28 31 32 29 33 10 30 34 Sector

Annual Report 2010 9W1517 Final Report - 76 - March 2011

Figure 38 Number of Redshank on the Orwell per sector between 2001 and 2010

Redshank on the Orwell

600

500 2001 - 2002 s l

a 2002 - 2003 u d

i 400 2003 - 2004 v i

d 2004 - 2005 n I

f 300 2005 - 2006 o

.

o 2006 - 2007 N

n 200 2007 - 2008 a e 2008 - 2009 M 100 2009 - 2010

0 01 02 21 03 18 17 22 23 05 41 40 06 39 38 19 24 37 26 35 25 36 11 27 12 28 31 32 29 33 10 30 34 Sector

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On the Orwell Estuary, the bird species discussed above, consistently show higher numbers within Sectors 5 and 41, which are on the border between the upper and mid estuary areas.

8.4.2 Stour Estuary

Shelduck

On the Stour Estuary the upper estuary is currently the area supporting the highest numbers of shelduck. The usage of this area has increased since 2006/07. The lower estuary is the area typically underused by the species but numbers were higher than the mid estuary in 2002/03 and 2003/04. The mid estuary has shown consistently similar numbers through all survey periods (Figure 39).

Shelduck numbers vary widely across each sector of the estuary from 2001/02 to 2009/10 (Figure 43). This highlights the natural fluctuations of the population on the estuaries.

Figure 39 Number of Shelduck on the Stour between 2001 and 2010

Shelduck on the Stour

2000

1800

1600

1400

1200 Upper Estuary 1000 Mid Estuary Lower Estuary 800

600

400

200

0 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

Annual report 2010 9W1517 Final Report - 78 - March 2011

Dunlin

The upper estuary is the most common area used by dunlin. Also, since 2008/09 numbers on the upper estuary appear to be increasing. The other two sections of the estuary show similar usage which is much lower than the upper estuary (Figure 40).

Numbers of dunlin on the Stour appear to have increased over many of the upper and middle sectors over time (Figure 44). The upper estuary area (Sector 20) had an exceptionally high number in 2009/10 which could have been due to disturbance causing double counting in this sector. Low numbers have always been recorded in the sectors along the boundary between the mid estuary and the low estuary.

Figure 40 Number of Dunlin on the Stour between 2001 and 2010

Dunlin on the Stour

12000

10000

8000

Upper Estuary 6000 Mid Estuary Lower Estuary

4000

2000

0 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

Annual report 2010 9W1517 Final Report - 79 - March 2011

Black-tailed godwit

Black tailed godwit is more common on the upper estuary. However, there has been a decline in numbers in this area since 2004/05 (Figure 41). No other estuary areas show a corresponding increase on the Stour, indicating that birds are going elsewhere. Numbers on the Orwell have increased and it is likely that some of the black-tailed godwit are moving to the Orwell. Also, the numbers of the mid and lower estuary are significantly lower than the upper section.

Numbers of black-tailed godwit have shown a decline in the upper estuary since 2001/02, although sectors 23 and 19 showed an increase in numbers in 2008/09. Numbers have fluctuated in the upper estuary, but 2009/10 numbers are considerably lower than the earlier years counts (Figure 45). Also, no other areas of the estuary show an increase in these years which could account for the decline. As above, some of these birds may be moving to the Orwell.

Figure 41 Number of Black-tailed godwit on the Stour between 2001 and 2010

Black-tailed godwit on the Stour

1200

1000

800

Upper Estuary 600 Mid Estuary Lower Estuary

400

200

0 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

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Redshank

Numbers of redshank have shown a variance and some natural fluctuation across the years of survey, with some high counts identified in the upper estuary in 2008/09 and counts in 2009/10 typically being lower than other years (Figure 42). A decline in numbers on the upper estuary in 2006/07 also corresponds to a similar decline in the mid estuary, indicating that birds were not moving along the estuary and were moving elsewhere.

The upper estuary is the most commonly used area of the estuary, with the lower and mid estuary showing much lower numbers, although there is more variation in the mid estuary.

Figure 46 indicates that there is a lot of variability between which areas of estuary redshank occupy and the number counted each year. This is predominantly due to the natural fluctuations in the populations. The upper sectors of the upper estuary did have higher numbers present in the earlier years of survey, from 2001/02 and 2004/05. The most recent count indicates that numbers are starting to increase in these sectors, but are not close to original count numbers. Redshank numbers have also shown an increase in sectors 32 and 14 which are on the edge of the upper estuary boundary. This may indicate a movement of birds up the estuary.

Figure 42 Number of Redshank on the Stour between 2001 and 2010

Redshank on the Stour

1400

1200

1000

800 Upper Estuary Mid Estuary 600 Lower Estuary

400

200

0 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 2009/10

Annual report 2010 9W1517 Final Report - 81 - March 2011

Figure 43 Number of Shelduck on the Stour per sector between 2001 and 2010

Shelduck on the Stour

350

300 2001 - 2002 s l

a 2002 - 2003

u 250 d

i 2003 - 2004 v i

d 200 2004 - 2005 n I

f 2005 - 2006 o

. 150 o 2006 - 2007 N

n 2007 - 2008 a 100 e 2008 - 2009 M 50 2009 - 2010

0 24 21 22 23 25 26 18 27 19 20 28 17 29 30 16 31 15 32 14 13 33 12 11 34 10 35 09 36 08 07 06 37 02 04 03 38 05 39 40 01 Sector

Annual Report 2010 9W1517 Final Report - 82 - March 2011

Figure 44 Number of Dunlin on the Stour per sector between 2001 and 2010

Dunlin on the Stour

3000

2500 2001 - 2002 s l

a 2002 - 2003 u d

i 2000 2003 - 2004 v i

d 2004 - 2005 n I

f 1500 2005 - 2006 o

.

o 2006 - 2007 N

n 1000 2007 - 2008 a e 2008 - 2009 M 500 2009 - 2010

0 24 21 22 23 25 26 18 27 19 20 28 17 29 30 16 31 15 32 14 13 33 12 11 34 10 35 09 36 08 07 06 37 02 04 03 38 05 39 40 01 Sector

Annual Report 2010 9W1517 Final Report - 83 - March 2011

Figure 45 Number of Black-tailed godwit on the Stour per sector between 2001 and 2010

Black-tailed godwit on the Stour

450

400 2001 - 2002 s

l 350

a 2002 - 2003 u d

i 300 2003 - 2004 v i

d 2004 - 2005

n 250 I

f 2005 - 2006 o

. 200

o 2006 - 2007 N

n 150 2007 - 2008 a e 2008 - 2009

M 100 2009 - 2010 50

0 24 21 22 23 25 26 18 27 19 20 28 17 29 30 16 31 15 32 14 13 33 12 11 34 10 35 09 36 08 07 06 37 02 04 03 38 05 39 40 01 Sector

Annual Report 2010 9W1517 Final Report - 84 - March 2011

Figure 46 Number of Redshank on the Stour per sector between 2001 and 2010

Redshank on the Stour

250

2001 - 2002 200 s l

a 2002 - 2003 u d

i 2003 - 2004 v i

d 150 2004 - 2005 n I

f 2005 - 2006 o

.

o 100 2006 - 2007 N

n 2007 - 2008 a e 2008 - 2009 M 50 2009 - 2010

0 24 21 22 23 25 26 18 27 19 20 28 17 29 30 16 31 15 32 14 13 33 12 11 34 10 35 09 36 08 07 06 37 02 04 03 38 05 39 40 01 Sector

Annual Report 2010 9W1517 Final Report - 85 - March 2011

8.5 Harwich Haven Bird Sub-group Meeting

A meeting of the bird sub-group was held in June 2010. The meeting was to discuss the findings of the BTO report summarised in the 2009 annual report and discuss general bird distributions of birds along the Stour and Orwell Estuaries based on the surveys undertaken and other factors which may be of relevance. The conclusions of the meeting are summarised below.

8.5.1 General observations

Through the 10 years of surveys that have been undertaken on the estuaries, the Suffolk Wildlife Trust has concluded that bird numbers seem to have remained fairly stable on the estuaries. However, disturbance to birds during high water seems to have become more of an issue. Knot seem to favour the lower Orwell Estuary but disturbance has been a big factor influencing numbers of birds. However, it does appear that knot are becoming less disturbed possibly because prey species have become depleted in certain areas of the estuaries.

The surveys also indicate that black-tailed godwit appear to be using the Trimley Reserve area but numbers do fluctuate highly. Also, numbers of dunlin on the Orwell Estuary have shown some fluctuation. Large numbers of birds are moving between estuaries, going from the Orwell Estuary to roost on the Stour Estuary. However, there don’t seem to be any sign of roosting movements from the Orwell Estuary to the .

The RSPB have noted through their research that black-tailed godwit numbers seem to be declining in mid-winter months. This is thought to be due to prey depletion, particularly in the Mistley area. However, bar-tailed godwits have increased in number which could indicate a change in habitat in the Stour Estuary. In addition, dunlin numbers have shown a decrease over the last 10 years whereas numbers of knot have been stable.

A project is underway monitoring bird ringing results (the ‘Turnover Project’) which has ringed 279 redshank and 1300 observations have been made of the coloured rings which should show good results for how the birds are using the estuary.

8.5.2 High and low water count comparison

The differences between the high and low water counts were also discussed during the meeting. BTO data was reviewed in relation to the general observations for each estuary (detailed above) and the count data and trend analysis. For dunlin, the trends calculated using the totals from the high water count showed different patterns to the trends calculated using the low water totals. This is comparable to observations of dunlin numbers and patterns on the Orwell Estuary but not for the Stour Estuary. It was thought that there may be changes to the roosting populations which could be influencing the trends analysis for the low water data. Also, a very high or low count for one year could influence the trend in a misleading way.

During the meeting it was agreed that a survey of roosting patterns could be useful to determine any large scale movements between the estuaries and adjacent estuaries which could then be affecting the results of the high water count data. It was proposed

Annual Report 2010 9W1517 Final Report - 86 - March 2011

that these surveys would focus on spring tide roosting movements and occur 1 to 2 hours either side of high water (see results below in Section 8.6).

8.5.3 Other Factors

There are other factors which can influence bird abundances and distribution and it is important that these factors be considered within the monitoring. These factors include such issues as disturbance, prey abundance and distribution and factors influencing the birds in their breeding grounds.

It was suggested during the bird sub-group meeting that ringed plover numbers could have shown a decline due to high levels of recreational disturbance. Disturbance appears to be increasing on the estuaries with more walkers particularly with dogs using the site. In some areas of the estuaries, i.e. those areas where the intertidal zone is narrow, disturbance is likely to be more of an issue, especially at high water periods. This could affect numbers in the high water counts where more birds are moving away from the Orwell to roost elsewhere.

Bait digging is also considered to be a factor influencing bird numbers as the removal of the bait reduces the food supply for the birds. Bait diggers have voiced concerns that they have to dig for longer to find worms and that the worms are becoming smaller in size. A voluntary bait digging code has been adopted during the winter period which has restricted the areas used for bait digging.

This issue will be investigated further, using the data provided by UnicoMarine on biomass (wet weight) and abundance of species, to work out the average size of the key bait digging species.

8.6 Bird movements

Trends in bird numbers were analysed previously and discussed in previous reports. The BTO were requested to undertake trends analysis of the data to look at unit trends against high water count totals. The results were discussed at the bird sub-group meeting where it was agreed that it would be useful to undertake a study to monitor bird movements from and to the Stour and Orwell estuaries to try and determine if birds were staying within the estuarine complex or flying off elsewhere.

Bird movements have been recorded on the 8th and 25th November, 7th December 2010 and 24th January 2011 at two locations: Ha’penny Pier and Stone Point. Preliminary analysis of the results has been undertaken to show gross movement patterns. Further analysis will be carried out to look into particular species movements.

The movement to and from the Orwell and Stour estuaries are presented in Figure 47, Figure 48, Figure 49 and Figure 50 respectively.

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Figure 47 Proportion of the movements towards the Orwell Estuary

Stour Bathside Sea channel Erwarton Hamford Mid-channel Walton

Figure 48 Proportion of the movements from the Orwell Estuary

Bathside Stour Hamford Mid-channel Open sea

As shown on Figure 47, most of the birds (60%) moving to the Orwell estuary have been recorded arriving from the Stour estuary, with 20% from Bathside, 15% from the sea channel and the remaining 5% from Walton, Mid-channel, Hamford and Erwarton. The data presented in Figure 48 shows that 65% of the birds at the Orwell move on to Bathside Bay, with 20% to the Stour and 10% to Hamford Water and very few going to the open sea or the mid-channel.

Annual Report 2010 9W1517 Final Report - 88 - March 2011

Figure 49 Proportion of the movements towards the Stour Estuary

Orwell Mid-channel Hamford Sea channel

Figure 50 Proportion of the movements from the Stour Estuary

Orwell Shotley Marina Mid-channel Sea channel Stone point

Figure 49 and Figure 50 show that of the birds present on the Stour most of the birds (more than 90%) come from the Orwell estuary. Few come from the mid-channel, Hamford Water and the sea channel. In addition, many that leave the Stour fly to the Orwell.

The results suggest that most of the birds stay within the Stour and Orwell Estuary complex. The RSPB believe that there is very little movement into or out of the two

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estuaries and many of the birds fly between the two exclusively (Rick Vonk, Pers. Com.).

The dominant species showing movements were cormorant, dark bellied brent goose, oystercatcher, lapwing, golden plover, grey plover, knot, dunlin and turnstone.

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9 STOUR AND ORWELL CONDITION ASSESSMENT REPORT

Natural England’s assessment at the end of 2005 was that much of the Stour and parts of the Orwell estuary were in unfavourable declining condition. The reason given for adverse condition was stated as: “Coastal squeeze and other - specify in comments.” Details of the “other” reasons were given as:

“Erosion (while partly natural) is partly attributable to coastal squeeze; also possible contribution from recreational disturbance, water quality factors, and maintenance dredging. Agreed mitigation is in place in respect of maintenance dredging, and subject to comprehensive monitoring which is reported to EN and other regulators. However, although English Nature has no reason to assume it is not working, the monitoring results are not able as yet to confirm that it is working as indicated by modelling. It is expected that such confirmation is unlikely to be available until the end of the second five-year review in 2010. In the event that it is not, after an appropriate period possible to demonstrate that mitigational sediment replacement is working, or if further investigation indicates that adverse effects are arising from unmitigated maintenance dredging requirements arising from dredges previous to 1998-2000, it is likely that dredging will be then indicated as a reason for unfavourability.”

The unfavourable assessment was based on declining bird numbers (as highlighted by BTO WeBS alerts), long term salt marsh loss and an assumption of sea level rise leading to coastal squeeze.

The latest condition assessment (2010 – reported in 2011) has concluded that the majority of sections within the Stour and Orwell Estuaries are now considered to be in favourable condition.

Within the Stour Estuary, 8 out of 9 units are in favourable condition. The unit which is in unfavourable declining condition is adjacent to Manningtree in the upper estuary and is considered unfavourable due to coastal squeeze which is discussed in the notes as the erosion of the seaward edges of the intertidal mud and saltmarsh. Sea level rise is given as a potential reason for the erosion but this is not qualified. All other units are favourable within the Stour.

Within the Orwell estuary, there are 21 units of which 3 are unfavourable – declining; 4 are unfavourable – no change; the remaining 14 are considered to be in favourable condition. The units in unfavourable – declining condition are unit 1 in the upper estuary where coastal squeeze is given as the reason for the assessment whereby the outlet of Levington Creek is cited as preventing development of extensive salt marsh in this area; unit 8 (near Chelmondiston) is cited as experiencing coastal squeeze which has lead to the loss of pioneer saltmarsh; and unit 13 (Trimley) where coastal squeeze is cited as the cause of the condition status leading to loss of saltmarsh vegetation. The units classified as unfavourable – no change are 11, 12, 15 and 16 which occur around the mouth of the Orwell, and together with unit 13, continue up to the bend in the estuary at Collimer Point on the west side and up to Levington on the east side. Each of these units are considered to be unfavourable – no change due to the presence of sea walls causing coastal squeeze thereby constraining the natural development of saltmarsh.

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10 FINDINGS AND RECOMMENDATIONS

10.1 Findings

The results of the surveys and analysis undertaken within the last year are reviewed in sections 3 to 8 and where appropriate compared with the baseline. They demonstrate HHA’s compliance with the requirements placed upon them by the mitigation compensation and monitoring agreements, the Environmental Assessment process and the FEPA licence conditions. The following summary outlines the main findings of the information collated during the last year:

Bathymetry and topographic data

Bathymetric surveys have been undertaken of the Stour and Orwell up to a level of about +1.5 m CD to ensure adequate overlap with the LiDAR surveys and full level coverage of the estuaries. Following analysis of the initial results there was some technical difficulty in comparing the 2005 and 2010 surveys. The problems appeared to be focused on the 2010 bathymetry and could be caused by timing errors in the positioning system or unpredictable squat behaviour of the survey vessel.

The Orwell and a proportion of the Stour have been re-surveyed and the results are currently being analysed. More details will be available at the meeting and it is hoped that the analysis can be made on the repeated surveys and added to this report as an addendum. If it transpires that there are further problems with this data, the full survey may need to be re-run and included in the report for 2011.

Benthic Monitoring

Stour and Orwell Estuaries

The annual benthic monitoring programme is currently in its 4th year and is undertaken by Thomson UnicoMarine. A detailed analysis will be conducted after the fifth year but initial results and analysis are showing that there have only been minimal changes between biotopes within the estuaries, particularly within the upper estuaries. In other areas it is generally a change in dominance of species rather than a change in species within the areas.

Felixstowe South Reconfiguration Monitoring

The monitoring on this site has been undertaken over three years, two of which were undertaken during the reconfiguration works. The only significant change was a shift in sediment composition at Station 33 between 2008 and 2009. As the change was a loss of Silt/Clay and affected only one sample, which is not the closest to the dredging or development areas, it is unlikely to be a result of those activities. It is also a shift between pre-existing communities, rather than an impoverishment. It could be due to natural cyclical changes or slight changes in sampling position. There was no community change between 2009 and 2010

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Trimley Marshes Realignment site

For Trimley managed realignment site, over the ten years of monitoring, the site has become an established intertidal benthic community which supports a wide range of waterfowl and contributes to maintaining the integrity of the internationally designated sites.

The starlet sea anemone Nematostella vectensis has been collected during surveys at the Trimley site since September 2007. This species is protected due to its limited distribution and vulnerability, and therefore, colonisation at the Trimley site is a notable achievement. In survey 20, 38 individual starlet sea anemones were collected from all of the cores across the site.

Saltmarsh at the site has thrived, and in line with the design criteria for Trimley, a diverse community has developed but is unlikely to exceed the 30% threshold for vegetative growth.

The period of monitoring as specified within the Mitigation and Monitoring Package is now complete and the ten years of monitoring has provided a clear indication of the development and successional changes within the site, a clear sign of the success of this habitat realignment site.

Future plans for the site will be discussed in consultation with the relevant stakeholders and authorities at the annual meeting in March 2011.

Trimley and Shotley Habitat Enhancement Sites

The Trimley and Shotley Habitat Enhancement Sites were established in 2003 and have been monitored every year since. The recharge sites on both sides of the estuary are fully functioning habitats which support a variety of benthic infauna and contribute to SPA designated habitat for over-wintering birds at low tide.

Although some of the recharge material may have eroded on the South Shotley side, the habitat enhancement sites are achieving the objectives set out in the CMMP of providing intertidal feeding habitat, and increasing the exposure of the area for longer in the tidal cycle (particularly at Trimley).

Further monitoring will continue until 2012 when the ten years of monitoring will be complete and more long-term objectives for the site may be established.

Bird Distribution and Abundance

WeBS Alerts

Of the species evaluated at the Stour and Orwell SPA, 12 species have had alerts triggered. High Alerts have been triggered for four species; cormorant, lapwing, dunlin and black-tailed godwit. Great crested grebe and ringed plover were previously recorded as High Alert species in 2004/05 but have now been reduced to Medium Alert. Other Medium Alert species include goldeneye, grey plover, redshank, shelduck, wigeon and pintail. Dark-bellied brent goose was previously on Alert status but has since been reduced, indicating that numbers have increased.

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Low Water Counts

Trends in populations of some species in the SPA continued in 2009/10. Numbers of pintail, black-tailed godwit and redshank have declined strongly in the SPA over the 11 winters to 2009/2010, primarily owing to substantial reductions in the populations wintering on the Stour (numbers of black-tailed godwit have increased on the Orwell). In 2009/10, the first strong trends in the dunlin population of the Orwell were apparent, where they have been decreasing since the start of monitoring (they have increased on the Stour.

Some changes in the distribution of species within the SPA are clear but these assessments are subjective and analysis of changes in the distribution of species is required from the data. Three species (ringed plover, grey plover and turnstone) were more or less absent in the Upper Orwell. Black-tailed godwit appears to have retreated to the top of the Stour, where it used to be widespread. Several species have become scarce in Copperas Bay and some were largely absent in 2009/10 (wigeon, pintail and redshank).

Roosting Movements

Preliminary analysis of results suggest that most of the birds stay within the Stour and Orwell Estuary complex and are not moving out of the estuaries to roost. Further analysis of specific species movements will be made but the dominant species showing movements were cormorant, dark bellied brent goose, oystercatcher, lapwing, golden plover, grey plover, knot, dunlin and turnstone.

10.2 Recommendations

Future Monitoring and Analysis Strategy

• The monitoring for the Trimley realignment site has been carried out for 10 years. The site is meeting its objectives and there are no reasons to expect that this will not continue. The Regulators group should therefore discuss whether the monitoring can now be discontinued or whether there is a requirement for further monitoring. • It is recommended that the majority of monitoring studies continue as planned but with reduced frequency of monitoring for the enhancement sites; and • The Regulators group should discuss the requirement for further bird movement/roosting surveys in light of the preliminary results.

Future Mitigation Strategy

• A review of the North Shelf area should be discussed and agreement made as to the future inclusion of this site in the sediment replacement strategy • The findings of the bathymetry results from 2009/2010 and the LiDAR data should be discussed in terms of the sediment replacement strategy.

Future Regulators meetings

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It is recommended that the meetings are continued to be held in March of each year to enable the results of the annual benthic monitoring survey to be included in the annual reporting.

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11 REFERENCES

° Ashelby, C.W., Worsfold, T.M. and Dyer, M.F. (2004). Intertidal fish and shrimp surveys of the Stour and Orwell estuaries. Analysis of regular trawls taken between September 2002 and October 2003. Unicomarine Report HHAYMar2004 to Harwich Haven Authority. March 2004.

° Ashelby, C.W. (2005). Intertidal fish and shrimp surveys of the Stour and Orwell estuaries. Analysis of regular intertidal trawls taken between December 2003 and December 2004. Unicomarine Report HHAYOct2005 to Harwich Haven Authority. October 2005.

° Austin, G.E., Collier, M.P., Calbrade, N.A., Hall, C. and Musgrove, A.J. (2008). Waterbirds in the UK 2006/07: The Wetland Bird Survey. BTO/WWT/ RSPB/JNCC, Thetford.

° Banks, A., Collier, M.P., Austin, G.E., Hearn, R.D. and Musgrove, A.J. (2006). Waterbirds in the UK 2004/05. The Wetland Bird Survey.

° Bathside Bay Container Port Planning Applications (1976 & 1986). Environment Statement. April 2003.

° Brackenreed-Johnston, G., Worsfold, T.M., Smith, S.W, Ashelby, C.W. and Dyer, M.F. (2009a). Stour and Orwell Estuaries Fish and Shrimp Monitoring. An overview of routine intertidal surveys between May 2002 and February 2008, with discussion of data collected between April 2006 and February 2008. Unicomarine Report HHA66 to Harwich Haven Authority. March 2009.

° Brackenreed-Johnston, G., Ashelby, C.W., Smith, S.W., Dyer, M.F. and Worsfold, T.M. (2009b). Stour and Orwell Estuaries Fish and Shrimp Monitoring. An overview of routine pelagic trawl surveys conducted between April 2002 and February 2008, with discussion of data collected between April 2006 and February 2008. Unicomarine Report HHA65 to Harwich Haven Authority. March 2009.

° British Trust for Ornithology (BTO, 2011). WeBS Alerts. Available from URL: www.bto.org.uk/webs/alerts. Accessed 27/01/2011

° British Trust for Ornithology (BTOa). WeBS Alerts. Available from URL: www.bto.org.uk/webs/alerts. Accessed 08/01/2010

° BTO (2009b). Research Report 540. Methods of comparing low-tide trends for Wetland Bird Survey count sectors with wider regions: a pilot study for three wader species on the Stour and Orwell Estuaries SPA. A report to Haskoning UK Ltd and Harwich Haven Authority. November 2009.

° Calbrade, N.A., Holt, C., Austin, G.E., Melland, H., Hearn, R., Stroud, D., Wotton, S., and and Musgrove, A.J. (2010). Waterbirds in the UK 2008/09: The Wetland Bird Survey. BTO/WWT/ RSPB/JNCC, Thetford.

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° Campos, J. and Van der Veer, H.W. (2008). Autecology of Crangon crangon (L.) with an emphasis on latitudinal trends. Oceanography and Marine Biology: An Annual Review, 46, 65-104.

° Collier, M.P., Banks, A.N., Austin, G.E., Girling, T., Hearn, R.D. and Musgrove, A.J. (2005). The wetlands bird survey 2003/2004: Wildfowl and wader counts. BTO/WWT/RSPB/JNCC/ Thetford.

° Dyer, M.F. (2001a). Stour and Orwell Estuaries. Fish and Shrimp Monitoring. Analysis of monthly fish and shrimp trawls taken at twelve stations in the Stour and Orwell estuaries between June 1999 and June 2000. Report to Harwich Haven Authority. Unicomarine Report St-Or_Beam_Jan01. January 2001.

° Dyer, M.F. (2001b). Stour and Orwell Estuaries: Analysis of monthly zooplankton trawls taken at twelve stations in the Stour and Orwell between June 1999 and June 2000. Unicomarine Report St-Or_Plank_Jan01 to Harwich Haven Authority. January 2001.

° Dyer, M.F., Ashelby, C.W. and Worsfold, T.M. (2002). Intertidal young fish and shrimp surveys of the Stour and Orwell Estuaries. Analysis of monthly trawls taken between May and August 2002. Report to Harwich Haven Authority. Unicomarine report HHAYOct2002. October 2002.

° English Nature (2001).The success of creation and restoration schemes in producing intertidal habitat suitable for waterbirds. English Nature Research Report No. 425.

° Felixstowe South Reconfiguration (FSR) (1997). Post deepening and Trinity III (2). Environmental Statement Volume 1. November 2003.

° Finbow, L.A. , Pears, S. & Worsfold, T.M. 2011 Felixstowe South Reconfiguration: Trawl and macrofaunal (Shipek grab) monitoring surveys, July 2010. Unicomarine Report HHAFEL10 (HHA71) to Harwich Haven Authority, February 2011.

° HR Wallingford and PDE (1997). Harwich Haven Approach Channel Deepening – Environmental Statement.

° PDE and HR Wallingford (1998). Mitigation and Monitoring Package (MMP). Report to Harwich haven Authority 1998.

° PDE and HR Wallingford (2001). Mitigation and Monitoring for the Stour and Orwell Estuaries SPA (and Hamford Water): Annual Report. Report to the Harwich Haven Authority. June 2001.

° Pears, S.A. & Worsfold, T.M., 2010. Analysis of macroinvertebrate samples taken in July 2010 from the Inner Gabbard East disposal site. Unicomarine Report HHAGABE10 (HHA72) to Harwich Haven Authority, February 2011

° Ravenscroft, N., Parker, B., Vonk, R. and M. Wright. (2007). Disturbance to waterbirds wintering in the Stour-Orwell estuaries SPA. A report from Wildside Ecology to the Suffolk Coast and Heaths Unit. 1-74pp

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° Royal Haskoning (2007a). Environmental Trends on the Stour and Orwell Estuaries. January 2007.

° Royal Haskoning (2007b). Mitigation and monitoring for the Stour and Orwell Estuaries SPA and Hamford Water SPA. Annual Review 2007. November 2007.

° Royal Haskoning (2008a). Mitigation and Monitoring for the Stour and Orwell Estuaries SPA and Hamford Water SPA. Annual Review 2008. November 2008.

° Royal Haskoning (2008b). Ornithological Trends on the Stour and Orwell Estuaries. October 2008).

° Royal Haskoning (2009a). Trimley Managed Realignment Site: Annual Monitoring Report (2009). Written on behalf of the Harwich Haven Authority. December 2009.

° Royal Haskoning (2009b). Trinity III Habitat Enhancement Monitoring 2009. Annual Report written on behalf of the Harwich Haven Authority. December 2009.

° Royal Haskoning (2009c). Mitigation and Monitoring for the Stour and Orwell Estuaries SPA and Hamford Water SPA. Annual Review 2009.

° Royal Haskoning and HR Wallingford (2003). Harwich Haven Approach Channel Deepening: Compliance Report November 1998-August 2003.

° Royal Haskoning and HR Wallingford (2005). Mitigation and Monitoring for the Stour and Orwell Estuaries SPA and Hamford Water SPA: Five Year Review 2005. Report to the Harwich Haven Authority. November 2005.

° Royal Haskoning and HR Wallingford (2006). Mitigation and Monitoring for the Stour and Orwell Estuaries SPA and Hamford Water SPA: Five-YearLY Review: Stage Two, 2006. Report to the Harwich Haven Authority. November 2006.

° Suffolk Wildlife Trust (SWT) (2010). Ornithological Monitoring of the Stour and Orwell Estuaries. Winter 1999/2000 to 2009/2010. July 2010.

° Suffolk Wildlife Trust (SWT) (2009). Ornithological Monitoring of the Stour and Orwell Estuaries. Winter 1999/2000 to 2008/2009. July 2009.

° Wallingford Environmental Surveys (WES) (2009). Shotley and Trimley River Orwell Foreshore Monitoring. Report Topo1_09. September 2009.

° Worsfold, T.M. and Dyer, M.F. (2009). Stour and Orwell Estuaries annual benthic monitoring report: July 2009 survey. Unicomarine Report HHASTO09 (HHA69) to Harwich Haven Authority, November 2009.

Annual Report 2010 9W1517 Final Report - 98 - March 2011 Appendix A:

Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Following the 2010 Regulators Meeting (16th March), it was decided a summary of biotopes and dominant species would help interpretation of the results of the Stour and Orwell annual monitoring of the benthos.

A biotope is defined as the combination of an abiotic habitat and its associated community of species (Connor et al., 2004). There is a classification hierarchy: broad habitats (EUNIS Level 2, e.g. littoral sediments, infralittoral rock), main habitats (EUNIS Level 3, e.g. littoral mud, sublittoral coarse sediment), biotope complexes (EUNIS Level 4, e.g. sublittoral coarse sediments in variable salinity) and biotopes (EUNIS Level 5, e.g. Nephtys hombergii, Macoma balthica and Streblospio shrubsolii in littoral sandy mud). EUNIS Level 1 defines the marine environment and Level 6 (sub-biotopes) are not considered here. Each level is represented by a group of letters in a biotope code, with letters separated by punctuation marks. For example, the biotope named above is coded as LS.LMu.MEst.NhomMacStr; note that there are four groups of letters separated by punctuation to represent EUNIS Levels 2-5.

A review of biotopes recorded from the Stour, Orwell and approaches to Harwich, including the Gabbard was included in the biotope distribution and data review report (Worsfold, 2005). Eighty five biotopes are recorded for the area. However, many of these are known only from outside the estuaries, from restricted areas or from habitats, such as boulders, that would not be expected to be sampled by Shipek grabs. The following biotope list is therefore restricted to those recorded from the annual monitoring surveys in 2008 (Worsfold & Dyer, 2008), 2009 (Worsfold & Dyer, 2009) and 2010 (this report).

LS.LMu.UEst.Hed LS (Littoral sediments) LMu (Littoral mud) UEst (Polychaete / oligochaete dominated upper estuarine mud shores) Hed (Hediste diversicolor in littoral mud)

Biotope description Typical habitat: mud or sandy mud in variable or reduced salinity, typically in sheltered inlets and the upper reaches of estuaries on the mid to lower shore. Biology: infauna usually dominated by harbour ragworms (Hediste diversicolor); other typical species include several species of oligochaete worms, often including Heterochaeta costata, which has a restricted salinity range; there are usually small polychaete worms, such as Streblospio shrubsolii and Manayunkia aestuarina and the laver spire snail Hydrobia ulvae may be common. There is no typical epibiota except for mats of drifting algae such as Enteromorpha. There are three sub-biotopes: LS.LMu.UEst.Hed.Str (Hediste diversicolor and Streblospio shrubsolii in littoral sandy mud) has a higher proportion of small polychaetes, LS.LMu.UEst.Hed.Cvol (Hediste diversicolor and Corophium volutator in littoral mud) has more mud amphipods (Corophium volutator) and LS.LMu.UEst.Hed.Ol (Hediste diversicolor and oligochaetes in littoral mud) has a higher proportion of oligochaetes. An average of 7,754 animals per m2 was recorded for this biotope in 2003.

Typical species; top 5 species

HHA biotope summary Page 1 of 10 Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

The five most common species recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Hediste diversicolor (harbour ragworm) is a large active worm (predator and particle feeder) common in mudflats with variable salinity. It is a prey species for fish and birds and sometimes used for bait. Streblospio shrubsolii is a small burrowing worm (deposit feeder) common in mudflats with variable salinity and is also common in shallow water. Hydrobia ulvae (laver spire snail) is a small snail (deposit feeder) common on mudflats and saltmarsh and able to drift over wide areas at high tide; it forms aggregations and populations may fluctuate. It is a prey species for some fish and birds Polydora cornuta is a small burrowing worm (deposit feeder) that prefers stiff mud or clay in variable salinity on the lower shore or in shallow water. Heterochaeta costata is a small oligochaete worm (deposit feeder) that is restricted to variable or reduced salinity at the heads of estuaries or in lagoons or areas of freshwater runoff.

Distribution in the estuaries This is the target biotope for Group StA. It has been consistently recorded from the intertidal of the upper Stour. In addition, a few upper mid-shore sites were ascribed to it by the 1997 grab survey along with the saltmarsh erosion area, with Enteromorpha spp. on consolidated mud and channels between, of eastern Copperas Bay mapped in 2002.

Regional and national distribution Many areas of soft mud, especially channels between saltmarshes and at the extreme heads of estuaries, are referable to this biotope and it is probably widely distributed in all estuaries with areas of appropriate salinity and sediment.

Key species for bird feeding and bait digging Hediste diversicolor is an important bird feeding and bait species. Most of the other typical species are too small to be of interest to bait diggers or most birds but some birds may specialise in the smaller worms or Hydrobia.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology (especially salinity) and to chemical contamination but is less sensitive to smothering or disturbance (provided that the sediment type remains the same).

LS.LMu.MEst.HedMac MEst (Polychaete / bivalve dominated mid estuarine mud shores) HedMac (Hediste diversicolor and Macoma balthica in littoral sandy mud)

Biotope description Typical habitat: sandy mud or mud in full, variable or reduced salinity, typically in sheltered bays and estuaries across the whole shore. Biology: infauna with many harbour ragworms (Hediste diversicolor), as well as bivalves (such as Abra tenuis, baltic tellins, Macoma balthica, and cockles, Cerastoderma edule), small worms (Streblospio shrubsolii, Tharyx Type A, and

HHA biotope summary Page 2 of 10 Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

oligochaetes, such as Tubificoides benedii), laver spire snails (Hydrobia ulvae) and burrowing amphipods (Corophium volutator). There is no typical epibiota except for mats of drifting algae such as Enteromorpha. An average of 21,261 animals per m2 was recorded for this biotope in 2003.

Lugworms (Arenicola marina), which might represent a different biotope, are often missed by remote sampling methods, due to their large size and low density. Lugworm casts are found in many sandy mud areas, particularly on the Stour, near areas of LS.LSa.MuSa.MacAre. Pygospio elegans is a minor component of many samples in this biotope as well as in LS.LMu.MEst.NhomMacStr. Sand gapers (Mya arenaria) are common in parts of upper reaches of both estuaries, especially the north side of the Orwell.

Typical species; top 5 species The five most common species recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Tubificoides benedii is a small oligochaete (deposit feeder) worm that is common in estuarine mudflats. Streblospio shrubsolii (see above) Hydrobia ulvae (see above) Tharyx (Type A) is a small burrowing worm (deposit feeder) that may common in mudflats, particularly in the mid reaches of estuaries. Abra tenuis is a small bivalve (deposit feeder) found in mudflats and saltmarsh in variable salinity, particularly in the upper and mid shore.

Distribution in the estuaries This is the target biotope for Groups StB, StE, StG and OrB. It included most of the intertidal samples taken for the 1997 survey (Dyer, 2000). It was the most extensive biotope on the Stour and was also widespread on the Orwell. Cluster analysis of the 2003 data divided the original biotope into two groups that were assigned to different biotopes, although the communities did not fit perfectly. Samples from mid estuary and mid shore areas were assigned to LS.LMu.MEst.HedMac. Samples from the Trimley Setback Site also belong to the present biotope; the breach had been made and the habitat stabilised by 2002.

Regional and national distribution This is probably the most widespread estuarine mudflat biotopes nationally and is also common in sheltered muddy bays.

Key species for bird feeding and bait digging Hediste diversicolor is an important bird feeding and bait species. Many of the bivalves present in the biotope would also be important bird food and cockles may be fished commercially. Most of the other typical species are too small to be of interest to bait diggers or most birds but some birds may specialise in the smaller worms or Hydrobia.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology (especially salinity) and to chemical contamination but is less sensitive to smothering

HHA biotope summary Page 3 of 10 Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

or disturbance (provided that the sediment type remains the same). There is evidence that some of the area of intertidal mud had been lost since publication of the most recent Ordnance Survey map, especially in Copperas, Holbrook and Erwarton Bays. In these areas, erosion steps are present on the seaward edges of both the saltmarsh and mudflats.

LS.LMu.MEst.NhomMacStr NhomMacStr (Nephtys hombergii, Macoma balthica and Streblospio shrubsolii in littoral sandy mud)

Biotope description Typical habitat: sandy mud in variable salinity, typically in the upper reaches of estuaries on the mid to lower shore. Biology: infauna dominated by the small worm Streblospio shrubsolii; harbour ragworms (Hediste diversicolor), bivalves (such as baltic tellins, Macoma balthica) and laver spire snails (Hydrobia ulvae) may also be common. There is no typical epibiota except for mats of drifting algae such as Enteromorpha. Some rare species (the burrowing anemone Nematostella vectensis and the polychaete Alkmaria romijni) have been recorded from this biotope in the western Stour (Hill et al., 1996). The biotope has much in common with LS.LMu.MEst.HedMac and is only loosely distinguishable from it. An average of 29,246 animals per m2 was recorded for this biotope in 2003.

Typical species; top 5 species The five most common species recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Streblospio shrubsolii (see above) Tharyx (Type A) (see above) Mya arenaria (gaper) is a large deposit and filter feeding bivalve (though juveniles were more common than adults in samples) that was originally introduced from eastern North America. It can be common on the lower shore and in shallow water in muddy sand in sheltered estuaries and bays, including areas of reduced and variable salinity; it burrows deeply. It could potentially be harvested for human consumption or bait and may be important for bird feeding. Hydrobia ulvae (see above) Cerastoderma edule (edible cockle) is a medium sized filter feeding bivalve (though juveniles were more common than adults in samples) found both in estuaries and sheltered bays in full or variable salinity, mostly near the surface of muddy sand or sandy mud on the mid or lower shore. It could be harvested for human consumption or bait and is an important bird feed species.

Distribution in the estuaries This is the target biotope for Groups StC and OrA. Most of the upper Orwell and parts of the lower shore of the upper Stour were referred to this biotope by cluster analysis of samples from 2003. Some sites are typical of the described type but there were more bivalves than described as typical. Some rare species (the burrowing anemone Nematostella vectensis and the polychaete Alkmaria romijni) have been recorded from this biotope in the western Stour (Hill et al., 1996).

HHA biotope summary Page 4 of 10 Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Regional and national distribution Many areas of soft substrata in the mid and upper reaches of estuaries are referable to this biotope and it is probably widely distributed in all estuaries with areas of appropriate salinity and sediment.

Key species for bird feeding and bait digging Mya arenaria and Cerastoderma edule are important bird feeding and, potentially, bait and human food species. Some of the other bivalve present in the biotope would also be important bird food. Most of the other typical species are too small to be of interest to bait diggers or most birds but some birds may specialise in the smaller worms or Hydrobia.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology (especially salinity) and to chemical contamination but is less sensitive to smothering or disturbance (provided that the sediment type remains the same).

SS.SCS.SCSVS SS (Sublittoral sediment) SCS (Sublittoral coarse sediment) SCSVS (Sublittoral coarse sediments in variable salinity (estuaries)

Biotope description This biotope complex is not divided into biotopes so is treated as a whole. Typical habitat: mixed substrata in variable or reduced salinity, in shallow water in estuaries Biology: varied infauna and epifauna as biotopes not defined within complex. Typical species in annual monitoring surveys listed below. An average of 2,750 animals per m2 was recorded for this biotope in 2008.

Typical species; top 5 species The five most common species recorded (other than Nematoda) in this biotope for the 2008 annual monitoring survey (in which this biotope was first recorded at a monitoring station) are listed below: Sphaerosyllis taylori is a very small mobile worm (possible predator) found in shallow water in mixed substrata. Aphelochaeta marioni is a small burrowing worm (deposit feeder) that may be common in muddy sediment with some mixed substrata on the lower shore and in shallow water in variable salinity. Syllidia armata is a very small mobile worm (predator) found in shallow water in mixed substrata. Mediomastus fragilis is a small burrowing worm (deposit feeder) found in shallow mixed substrata. Tubificoides benedii (see above)

Distribution in the estuaries The complex was recorded at one station in Group StF in 2008. In 2003, it was recorded from off Parkeston, in the outer Stour Estuary.

HHA biotope summary Page 5 of 10 Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Regional and national distribution As the biotopes are not defined it is not possible to comment on national distribution.

Key species for bird feeding and bait digging Most of the species recorded are too small to be of interest to birds. Subtidal habitats are generally inaccessible to bait diggers and many birds.

Sensitivity The complex probably includes a series of transitional communities that are produced by distrurbance and likely to change with changes in substratum type and hydrology, as well as with changes such as smothering or disturbance.

SS.SMu.SMuVS.AphTubi SMu (Sublittoral cohesive mud and sandy mud communities) SMuVS (Sublittoral mud in variable salinity (estuaries) AphTubi (Aphelochaeta marioni and Tubificoides spp. in variable salinity infralittoral mud)

Biotope description Typical habitat: mud or sandy mud, sometimes with mixed substrata, in full or variable salinity, typically in the mid to lower reaches of estuaries and sheltered inlets in shallow water. Biology: infauna characterised by the small worm Aphelochaeta marioni and oligochaete worms such as Tubificoides amplivasatus. Other worms may be frequent. An average of 6,969 animals per m2 was recorded for this biotope in the richest cluster in 2003.

Typical species; top 5 species The five most common taxa recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Aphelochaeta marioni (see above) Streblospio shrubsolii (see above) Phoronis are small worms (filter and deposit feeders) that live buried in mud in sandy tubes. They may be very common in shallow water in estuaries and sheltered bays. Melinna palmata is a medium sized burrowing worm (deposit feeder) found in mud on the lower shore and in shallow water, where it may be very common. Nephtys hombergii (a type of catworm) is a large active worm (predator) that can be found in many different sediment types in a wide range of depths but is particularly common in shallow water mud in estuaries.

Distribution in the estuaries This is the target biotope for Groups StD and OrD. It is one of the principal subtidal biotopes of the estuaries, as identified by cluster analysis of 2003 data. Most of the fauna from the sediment grab samples recorded in previous surveys (Dyer, 2000) was referred to the equivalent of this biotope. Much of Holbrook Bay, mapped as intertidal in most maps and charts, fits SS.SMu.SMuVS.AphTubi on the basis of its fauna (Dyer, 2000). July 2002 dredge samples containing mud or muddy mixed sediment were assumed to belong to it. Most samples were typical of the described biotope. Certain areas proved to contain more gravel and overlap with IMX biotopes, however (Dyer & Worsfold, 2001). There was also considerable overlap with other mud biotopes.

HHA biotope summary Page 6 of 10 Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Regional and national distribution This is probably one of the most widespread soft substratum biotopes in estuarine shallow water throughout the country. It is also likely to be widespread in sheltered inlets and bays.

Key species for bird feeding and bait digging Catworms (Nephtys hombergii) would be suitable for bird feed and bait if accessible. Most of the other species recorded are too small to be of interest to birds. Subtidal habitats are generally inaccessible to bait diggers and many birds.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology and to chemical contamination but less sensitive to smothering or disturbance (provided that the sediment type remains the same).

SS.SMu.SMuVS.PolCvol PolCvol (Polydora ciliata and Corophium volutator in variable salinity infralittoral firm mud or clay)

Biotope description Typical habitat: clay or peat, with mud, in variable salinity, often in the lower reaches of estuaries and sheltered inlets in shallow water. Biology: infauna characterised by the small worm Polydora ciliata, or P. cornuta, and the burrowing amphipod Corophium volutator, which may vary in abundance. Other worms may be frequent. An average of 192 animals per m2 was recorded for this biotope in 2008.

Typical species; top 5 species The five most common species recorded in this biotope for the 2008 annual monitoring survey (in which this biotope was first recorded at the monitoring stations) are listed below: Polydora cornuta (see above) Eusarsiella zostericola is a very small ostracod crustacean (clam shrimp) that was originally introduced from eastern North America and lives on and above lower shore and shallow water mud in estuaries. Nucula nitidosa is a small bivalve (deposit feeder) that may be abundant in shallow water stiff mud or clay. Nephtys hombergii (see above) Chaetozone zetlandica is a small burrowing worm (deposit feeder) that lives in shallow water in the lower reaches of estuaries and sheltered locations in mixed and muddy substrata.

Distribution in the estuaries This biotope was recorded Group OrD in 2008 and 2009. Similar communities have also been found at other stations in the estuaries (Station 290) and offshore. The fauna was variable, as evidenced by the cluster group scatter.

Regional and national distribution

HHA biotope summary Page 7 of 10 Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

As the biotope is restricted to particular substratum types, it is probably scattered in its distribution around the country and may be widespread but unlikely to cover wide areas.

Key species for bird feeding and bait digging Catworms (Nephtys hombergii) would be suitable for bird feed and bait if accessible. Most of the other species recorded are too small to be of interest to birds. Subtidal habitats are generally inaccessible to bait diggers and many birds.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology and to chemical contamination. It would also be sensitive to smothering and disturbance, as these would necessarily affect the substratum type.

SS.SMu.SMuVS.NhomTubi NhomTubi (Nephtys hombergii and Tubificoides spp. in variable salinity infralittoral soft mud)

Biotope description Typical habitat: mud or sandy mud, in variable salinity, typically in the mid to lower reaches of estuaries and sheltered inlets in shallow water. Biology: infauna characterised by catworms, Nephtys hombergii and oligochaete worms such as Tubificoides amplivasatus. Other worms may be frequent. An average of 425 animals per m2 was recorded for this biotope in 2009.

Typical species; top 5 species The five most common species recorded in this biotope for the 2009 annual monitoring survey (in which this biotope was first recorded at the monitoring stations) are listed below: Nephtys (juv) most likely represents the young of N. hombergii (see above) Streblospio shrubsolii (see above) Aphelochaeta marioni (see above) Cossura pygodactyla is a very small burrowing worm (deposit feeder) found in various substrata, often in disturbed conditions. Ampharete grubei is a medium sized burrowing worm (deposit feeder) found in muddy substrata on the lower shore and in shallow water.

Distribution in the estuaries This biotope was recorded Group OrD in 2009. It was not easily recognised on the basis of 1997 cluster groups but inspection of individual sample data showed a dominance of Nephtys hombergii to be associated with reduced cirratulid (Aphelochaeta marioni) numbers. Analysis of 2003 data revealed the biotope in the estuaries (mainly in Harwich Harbour but also in the mid Stour) and offshore, mainly in Pennyhole Bay. Some 2003 estuary samples may represent an undescribed biotope related to SS.SMu.SMuVS.NhomTubi. The echiuran Maxmuelleria lankesteri was found in Harwich Harbour in July 2002 (Worsfold, 2002 – recorded as Echiurus echiurus) and may be an important food for fish (N. Britton, pers. comm.). Echiurans are known to emerge from the mud under anoxic conditions (Dyer et al., 1983). Such conditions could result from sediment dumping. The bivalve Saxicavella jeffreysii was often dominant.

HHA biotope summary Page 8 of 10 Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Regional and national distribution The biotope is likely to be widespread in shallow water mud throughout the country.

Key species for bird feeding and bait digging Catworms (Nephtys hombergii) would be suitable for bird feed and bait if accessible. Most of the other species recorded are too small to be of interest to birds. Subtidal habitats are generally inaccessible to bait diggers and many birds.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology and to chemical contamination. It is probably much less sensitive to smothering and disturbance and may represent a relatively disturbed sediment community.

SS.SMx.IMx.SpavSpAn SMx (Sublittoral mixed sediment) IMx (Infralittoral mixed sediment) SpavSpAn (Sabella pavonina with sponges and anemones on infralittoral mixed sediment)

Biotope description Typical habitat: muddy gravelly sand with pebbles, in full or slightly reduced or variable salinity, often in the lower reaches of estuaries and sheltered inlets in shallow water. Biology: characterised by fanworms, Sabella pavonina, which may form beds; epifauna, such as ascidians, sponges and anemones may be attached to the fanworm tubes. The infauna includes many small worms and crustaceans. An average of 17,089 animals per m2 was recorded in the richest cluster for this biotope in 2003.

Typical species; top 5 species The five most common taxa (other than Nematoda) recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Sabella pavonina (fanworm, spaghetti weed) is a large worm that builds muddy tubes attached to small stones or shells that are often buried in mud. The worms have crowns of tentacles that are extended for filter feeding. They may form extensive beds in shallow mixed substrata (sometimes on the lower shore) in estuaries and coastal areas, often with strong currents. Sabelliphilus elongatus is a very small crustacean that parasitises fanworms. Syllidia armata (see above) Aoridae are small Crustacea (deposit feeders) that build tubes in mud or attached to stones, shells, debris, or other tubes in shallow water. Aphelochaeta marioni (see above).

Distribution in the estuaries This is the target biotope for Groups StF and OrC. Fanworms (Sabella pavonina) have been found in dense patches on mud or mixed substrata on both estuaries, but particularly on the Orwell (Worsfold, 2002; Jessop et al., 2003). There is also a 6ha. patch of dense Sabella pavonina on the north-western edge of the Shelf and another (3ha.) to the south, which have been mapped by towed video (Worsfold & Dyer, 2004). Much of the undredged mud to the west of Landguard Point is similarly

HHA biotope summary Page 9 of 10 Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

colonised by fanworms (about 9ha.). The beds have dense Sabella and are good examples of the described biotope. Sample analysis suggests that there may be another bed off The Naze.

Regional and national distribution There seems to be little information on the distribution of this biotope nationally but it would be reasonable to expect scattered patches in many UK estuaries.

Key species for bird feeding and bait digging Subtidal habitats are generally inaccessible to bait diggers and many birds. We have found no evidence that fanworms are targeted by birds, although some of the associated species, which may include large Crustacea, could be of interest. Fanworm beds may also be important as shelter for fish nurseries.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology and to chemical contamination but less sensitive to smothering, as the tubes are raised above the mud surface. Disturbance could remove fanworms and change the biotope. There is some evidence that S. pavonina has increased in abundance in the estuaries.

HHA biotope summary Page 10 of 10 Appendix B:

Waterfowl Species Accounts 1999/2000 – 2009/10 APPENDIX B

WATERFOWL SPECIES ACCOUNTS 1999/2000 – 2009/10

Distribution maps of mean winter numbers for principal species from 1999/00 to 2009/10 are available in the main SWT report (SWT, 2010).

Brent goose The population has been fairly stable in the SPA at around 2000 birds since 1999, split about equally between the two estuaries in some years and alternating between them in others, although in recent winters larger numbers have been wintering on the Stour, leading to a small increase in the mean SPA population (2500 birds).

Few birds used Bathside Bay in the Stour in 2009/10, where they were frequent in the previous two winters. Otherwise, the distribution of geese has been fairly consistent between winters – concentrated in the lower reaches of the Orwell (especially Shotley Marshes and Thorpe Bay) and throughout the Stour.

Shelduck Declines in the SPA have been reversed in recent winters. Numbers stabilised on the Stour in 2009/10, where mean and peak populations were similar to those of 1999/2000. A positive trend was recorded for the first time on the Orwell owing to increases in the mean population (at 640 birds, 80 more than the previous high in 2008/09).

Birds show no particular areas of concentration on the Orwell, but on the Stour are usually concentrated in the upper reaches of the estuary, and the larger bays of Copperas, Bradfield, Holbrook, Jacques and Bathside.

Wigeon Numbers continued to decline on the Orwell in 2009/10 after sharp increases early in the monitoring programme (the population was the lowest yet recorded – mean 1183 and peak 1336 birds). The recent contrasting increase in the Stour population was tempered in 2009/10 where the mean population dropped by almost 1300 birds, although the overall trend is still one of increase.

Distribution on both estuaries has changed little – most birds frequent Trimley Marshes on the Orwell (sections 31–34), the mudflats and saltmarsh around Colton Creek, Hare’s Creek and Jill’s Hole on the southern shore (sections 24–27), with smaller numbers of birds along the Nacton foreshore (section 37). On the Stour, the upper reaches of the estuary are favoured: Jacques Bay, Seafield Bay and Mistley and Stutton foreshores, and concentrations occur consistently at the mouth of the estuary on the northern shore in Erwarton Bay (sections 37–40). Notably, birds were absent from Copperas Bay in 2009/10.

Pintail The pronounced decline in mean and peak numbers on the Stour (and peak numbers in the SPA) continued in 2009/10. In the first four winters of monitoring, mean and numbers of 300-500 birds occurred on the Stour, but in recent winters numbers have been between 200-300 birds (229 in 2009/10).

There was a pronounced change in the distribution of birds in the SPA in 2009/10. On the Orwell, birds have always been most frequent on Trimley Marshes although scattered throughout the estuary, but in 2009/10 birds occurred almost exclusively on the former. On the Stour, the main concentrations of pintail used to be in Copperas, Holbroook and Seafield Bays, but birds were almost absent from these bays in 2009/10, and concentrated on the Mistley foreshore.

Oystercatcher Mean winter numbers have been stable in the SPA since 1999/2000 at between 2160 and 2806 birds and this was unchanged in 2009/10. Similar numbers winter on each estuary and populations have been largely stable. On the Orwell, most birds winter in the upper reaches, especially along the northern (Mulberry Middle and Pond Ooze). Birds are distributed widely in the Stour, and notable concentrations occur in the larger bays.

Ringed plover Despite the slight recover in the previous winter, the trend of decrease in the SPA in recent winters (particularly on the Orwell) continued in 2009/10. A mean population of only 71 birds was recorded on the Orwell in 2009/10, and the mean SPA population of 178 birds was the lowest recorded (previous low 213 birds in 2007/08).

Birds used to be scattered throughout both estuaries, but in 2009/10 practically all birds of the Orwell occurred in Thorpe Bay and on the Pin Mill shore. Once again, birds were absent from the uppermost mudflats of the Orwell around Pond and Black Oozes. On the Stour, the only notable concentrations were in Bathside, Jacques and Holbrook Bays.

Grey plover There have been minor fluctuations in numbers on the Stour (that supports most of the SPA population), but no significant changes in the population of the SPA since 1999/2000 (there were drops in the mean population of the Stour and SPA in 2009/10 – both were the lowest recorded). Few birds winter on the Orwell compared with the Stour.

As in previous years, the distribution of birds is strongly mid-estuary in the Stour and concentrated in Holbrook and Jacques Bays, although there were notable numbers present in Bathside Bay in 2009/10 as there have been in recent winters. On the Orwell, birds used to be well-spread along the estuary, but their distribution has become strongly mid-estuary, particularly on Nacton foreshore, and notably birds were more or less absent from Pond and Black Oozes that used to support good numbers of birds (as per ringed plover).

Lapwing After recent declines in the population of the SPA since a peak in 2004/05, particularly on the Stour, both mean and peak numbers (nearly 12000 birds in 2004/2005) remained low in 2009/2010.

Despite the large variation in numbers, the distribution of birds in the SPA has remained the same and there are consistent concentrations of birds in each estuary – in Jacques Bay, Seafield Bay, around Erwarton bay and at the head of the estuary on the Stour, and on the Strand, Trimley Marshes and Levington on the Orwell.

Knot After several winters of increase on the SPA (from a mean population of 4591 birds in 1999/2000 to 11655 in 2006/2007) numbers have dropped to means of 6-7000 birds in the last three winters. Practically all this variation has been caused by fluctuations in numbers on the Stour – numbers on the Orwell have steadily increased throughout monitoring from a mean populations of 956 birds in 1999/2000 to 2268 in 2009/10.

As in most winters, birds were concentrated on the wider mudflas of both estuaries in 2009/2010: Holbrook, Jacques, Bathside, Erwarton and especially Seafield Bays on the Stour, and Nacton and Mulberry Middle on the Orwell.

Dunlin There were statistical trends in the dunlin population for the first time, although declines have been apparent on the Orwell since early in the monitoring programme. Despite this, the mean winter population in the SPA has been relatively stable as most birds winter on the Stour, but in 2009/10 this was the highest recorded (17,036 birds with a peak of 20,976) owing to the largest Stour population of the 11 winters (mean 15,370 birds). The mean number recorded on the Orwell in 2009/2010, however, was only 1665 birds, the lowest since monitoring began when 3-4000 birds were present, and is further indication of the declining status of this species on this estuary.

Birds are well distributed on both estuaries at low tide, although relatively few birds occur on the southern shores of the Orwell.

Black-tailed godwit The strong decline in numbers on the Stour noted in previous reports continued in 2009/2010, whilst numbers remained relatively strong on the Orwell. The mean SPA population fell to below 1000 birds for the first time (899 birds) and was only 567 birds on the Stour (1628 in 2000/01). Peak numbers on the Orwell (746 birds) exceeded the Stour (674 birds) for the first time.

Despite recent occupation of most of the Orwell in recent winters, the population was concentrated at the head of the estuary once again, with small numbers scattered elsewhere. On the Stour, the species appears to have become restricted to the top of the estuary, and in 2009/2010 most birds occurred on the Mistley foreshore and in Seafield Bay, with small numbers elsewhere.

Curlew No trends were apparent for curlew in 2009/10, despite pervious indications of decline, owing to increase in the mean SPA populations (primarily caused by larger numbers on the Stour). Numbers on the Orwell remained relatively low compared with early winters in the monitoring programme.

Birds were well distributed throughout both estuaries 2007/2008, as they have been in all winters, and there are no obvious changes in distribution.

Redshank There has been a strong and consistent decline in both mean and peak numbers of redshank in the SPA since monitoring began. This has been caused by declines on the Stour where the mean population has fallen from around 2000 birds to 1500 in recent winters.

Birds are well spread on both estuaries, but recent indications of a decline in use of the mid-Stour, especially in Holbrook and Copperas Bays, were repeated in 2009/10.

Turnstone Previous strong increases in the population of the SPA were not repeated in 2009/10, owing to a substantial drop in the number of birds using the Orwell (a mean of only 97 birds compared with 207 in 2004/05), but a positive trend was still apparent on the Stour.

Birds were once again absent from Pond Ooze at the head of the Orwell where they used to occur in good numbers, and they were mainly confined to Mulberry Middle and Nacton. On the Stour, distribution appears to have remained more or less constant despite the increase in population, with the primary concentrations occurring in Erwarton and Holbrook Bays.

Appendix 5. Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Following the 2010 Regulators Meeting (16th March), it was decided a summary of biotopes and dominant species would help interpretation of the results of the Stour and Orwell annual monitoring of the benthos.

A biotope is defined as the combination of an abiotic habitat and its associated community of species (Connor et al., 2004). There is a classification hierarchy: broad habitats (EUNIS Level 2, e.g. littoral sediments, infralittoral rock), main habitats (EUNIS Level 3, e.g. littoral mud, sublittoral coarse sediment), biotope complexes (EUNIS Level 4, e.g. sublittoral coarse sediments in variable salinity) and biotopes (EUNIS Level 5, e.g. Nephtys hombergii, Macoma balthica and Streblospio shrubsolii in littoral sandy mud). EUNIS Level 1 defines the marine environment and Level 6 (sub-biotopes) are not considered here. Each level is represented by a group of letters in a biotope code, with letters separated by punctuation marks. For example, the biotope named above is coded as LS.LMu.MEst.NhomMacStr; note that there are four groups of letters separated by punctuation to represent EUNIS Levels 2-5.

A review of biotopes recorded from the Stour, Orwell and approaches to Harwich, including the Gabbard was included in the biotope distribution and data review report (Worsfold, 2005). Eighty five biotopes are recorded for the area. However, many of these are known only from outside the estuaries, from restricted areas or from habitats, such as boulders, that would not be expected to be sampled by Shipek grabs. The following biotope list is therefore restricted to those recorded from the annual monitoring surveys in 2008 (Worsfold & Dyer, 2008), 2009 (Worsfold & Dyer, 2009) and 2010 (this report).

LS.LMu.UEst.Hed LS (Littoral sediments) LMu (Littoral mud) UEst (Polychaete / oligochaete dominated upper estuarine mud shores) Hed (Hediste diversicolor in littoral mud)

Biotope description Typical habitat: mud or sandy mud in variable or reduced salinity, typically in sheltered inlets and the upper reaches of estuaries on the mid to lower shore. Biology: infauna usually dominated by harbour ragworms (Hediste diversicolor); other typical species include several species of oligochaete worms, often including Heterochaeta costata, which has a restricted salinity range; there are usually small polychaete worms, such as Streblospio shrubsolii and Manayunkia aestuarina and the laver spire snail Hydrobia ulvae may be common. There is no typical epibiota except for mats of drifting algae such as Enteromorpha. There are three sub-biotopes: LS.LMu.UEst.Hed.Str (Hediste diversicolor and Streblospio shrubsolii in littoral sandy mud) has a higher proportion of small polychaetes, LS.LMu.UEst.Hed.Cvol (Hediste diversicolor and Corophium volutator in littoral mud) has more mud amphipods (Corophium volutator) and LS.LMu.UEst.Hed.Ol (Hediste diversicolor and oligochaetes in littoral mud) has a higher proportion of oligochaetes. An average of 7,754 animals per m2 was recorded for this biotope in 2003.

Typical species; top 5 species

Appendix. 5, HHA biotope summary Page 1 of 10 Appendix 5. Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

The five most common species recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Hediste diversicolor (harbour ragworm) is a large active worm (predator and particle feeder) common in mudflats with variable salinity. It is a prey species for fish and birds and sometimes used for bait. Streblospio shrubsolii is a small burrowing worm (deposit feeder) common in mudflats with variable salinity and is also common in shallow water. Hydrobia ulvae (laver spire snail) is a small snail (deposit feeder) common on mudflats and saltmarsh and able to drift over wide areas at high tide; it forms aggregations and populations may fluctuate. It is a prey species for some fish and birds Polydora cornuta is a small burrowing worm (deposit feeder) that prefers stiff mud or clay in variable salinity on the lower shore or in shallow water. Heterochaeta costata is a small oligochaete worm (deposit feeder) that is restricted to variable or reduced salinity at the heads of estuaries or in lagoons or areas of freshwater runoff.

Distribution in the estuaries This is the target biotope for Group StA. It has been consistently recorded from the intertidal of the upper Stour. In addition, a few upper mid-shore sites were ascribed to it by the 1997 grab survey along with the saltmarsh erosion area, with Enteromorpha spp. on consolidated mud and channels between, of eastern Copperas Bay mapped in 2002.

Regional and national distribution Many areas of soft mud, especially channels between saltmarshes and at the extreme heads of estuaries, are referable to this biotope and it is probably widely distributed in all estuaries with areas of appropriate salinity and sediment.

Key species for bird feeding and bait digging Hediste diversicolor is an important bird feeding and bait species. Most of the other typical species are too small to be of interest to bait diggers or most birds but some birds may specialise in the smaller worms or Hydrobia.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology (especially salinity) and to chemical contamination but is less sensitive to smothering or disturbance (provided that the sediment type remains the same).

LS.LMu.MEst.HedMac MEst (Polychaete / bivalve dominated mid estuarine mud shores) HedMac (Hediste diversicolor and Macoma balthica in littoral sandy mud)

Biotope description Typical habitat: sandy mud or mud in full, variable or reduced salinity, typically in sheltered bays and estuaries across the whole shore. Biology: infauna with many harbour ragworms (Hediste diversicolor), as well as bivalves (such as Abra tenuis, baltic tellins, Macoma balthica, and cockles, Cerastoderma edule), small worms (Streblospio shrubsolii, Tharyx Type A, and

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oligochaetes, such as Tubificoides benedii), laver spire snails (Hydrobia ulvae) and burrowing amphipods (Corophium volutator). There is no typical epibiota except for mats of drifting algae such as Enteromorpha. An average of 21,261 animals per m2 was recorded for this biotope in 2003.

Lugworms (Arenicola marina), which might represent a different biotope, are often missed by remote sampling methods, due to their large size and low density. Lugworm casts are found in many sandy mud areas, particularly on the Stour, near areas of LS.LSa.MuSa.MacAre. Pygospio elegans is a minor component of many samples in this biotope as well as in LS.LMu.MEst.NhomMacStr. Sand gapers (Mya arenaria) are common in parts of upper reaches of both estuaries, especially the north side of the Orwell.

Typical species; top 5 species The five most common species recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Tubificoides benedii is a small oligochaete (deposit feeder) worm that is common in estuarine mudflats. Streblospio shrubsolii (see above) Hydrobia ulvae (see above) Tharyx (Type A) is a small burrowing worm (deposit feeder) that may common in mudflats, particularly in the mid reaches of estuaries. Abra tenuis is a small bivalve (deposit feeder) found in mudflats and saltmarsh in variable salinity, particularly in the upper and mid shore.

Distribution in the estuaries This is the target biotope for Groups StB, StE, StG and OrB. It included most of the intertidal samples taken for the 1997 survey (Dyer, 2000). It was the most extensive biotope on the Stour and was also widespread on the Orwell. Cluster analysis of the 2003 data divided the original biotope into two groups that were assigned to different biotopes, although the communities did not fit perfectly. Samples from mid estuary and mid shore areas were assigned to LS.LMu.MEst.HedMac. Samples from the Trimley Setback Site also belong to the present biotope; the breach had been made and the habitat stabilised by 2002.

Regional and national distribution This is probably the most widespread estuarine mudflat biotopes nationally and is also common in sheltered muddy bays.

Key species for bird feeding and bait digging Hediste diversicolor is an important bird feeding and bait species. Many of the bivalves present in the biotope would also be important bird food and cockles may be fished commercially. Most of the other typical species are too small to be of interest to bait diggers or most birds but some birds may specialise in the smaller worms or Hydrobia.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology (especially salinity) and to chemical contamination but is less sensitive to smothering

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or disturbance (provided that the sediment type remains the same). There is evidence that some of the area of intertidal mud had been lost since publication of the most recent Ordnance Survey map, especially in Copperas, Holbrook and Erwarton Bays. In these areas, erosion steps are present on the seaward edges of both the saltmarsh and mudflats.

LS.LMu.MEst.NhomMacStr NhomMacStr (Nephtys hombergii, Macoma balthica and Streblospio shrubsolii in littoral sandy mud)

Biotope description Typical habitat: sandy mud in variable salinity, typically in the upper reaches of estuaries on the mid to lower shore. Biology: infauna dominated by the small worm Streblospio shrubsolii; harbour ragworms (Hediste diversicolor), bivalves (such as baltic tellins, Macoma balthica) and laver spire snails (Hydrobia ulvae) may also be common. There is no typical epibiota except for mats of drifting algae such as Enteromorpha. Some rare species (the burrowing anemone Nematostella vectensis and the polychaete Alkmaria romijni) have been recorded from this biotope in the western Stour (Hill et al., 1996). The biotope has much in common with LS.LMu.MEst.HedMac and is only loosely distinguishable from it. An average of 29,246 animals per m2 was recorded for this biotope in 2003.

Typical species; top 5 species The five most common species recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Streblospio shrubsolii (see above) Tharyx (Type A) (see above) Mya arenaria (gaper) is a large deposit and filter feeding bivalve (though juveniles were more common than adults in samples) that was originally introduced from eastern North America. It can be common on the lower shore and in shallow water in muddy sand in sheltered estuaries and bays, including areas of reduced and variable salinity; it burrows deeply. It could potentially be harvested for human consumption or bait and may be important for bird feeding. Hydrobia ulvae (see above) Cerastoderma edule (edible cockle) is a medium sized filter feeding bivalve (though juveniles were more common than adults in samples) found both in estuaries and sheltered bays in full or variable salinity, mostly near the surface of muddy sand or sandy mud on the mid or lower shore. It could be harvested for human consumption or bait and is an important bird feed species.

Distribution in the estuaries This is the target biotope for Groups StC and OrA. Most of the upper Orwell and parts of the lower shore of the upper Stour were referred to this biotope by cluster analysis of samples from 2003. Some sites are typical of the described type but there were more bivalves than described as typical. Some rare species (the burrowing anemone Nematostella vectensis and the polychaete Alkmaria romijni) have been recorded from this biotope in the western Stour (Hill et al., 1996).

Appendix. 5, HHA biotope summary Page 4 of 10 Appendix 5. Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Regional and national distribution Many areas of soft substrata in the mid and upper reaches of estuaries are referable to this biotope and it is probably widely distributed in all estuaries with areas of appropriate salinity and sediment.

Key species for bird feeding and bait digging Mya arenaria and Cerastoderma edule are important bird feeding and, potentially, bait and human food species. Some of the other bivalve present in the biotope would also be important bird food. Most of the other typical species are too small to be of interest to bait diggers or most birds but some birds may specialise in the smaller worms or Hydrobia.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology (especially salinity) and to chemical contamination but is less sensitive to smothering or disturbance (provided that the sediment type remains the same).

SS.SCS.SCSVS SS (Sublittoral sediment) SCS (Sublittoral coarse sediment) SCSVS (Sublittoral coarse sediments in variable salinity (estuaries)

Biotope description This biotope complex is not divided into biotopes so is treated as a whole. Typical habitat: mixed substrata in variable or reduced salinity, in shallow water in estuaries Biology: varied infauna and epifauna as biotopes not defined within complex. Typical species in annual monitoring surveys listed below. An average of 2,750 animals per m2 was recorded for this biotope in 2008.

Typical species; top 5 species The five most common species recorded (other than Nematoda) in this biotope for the 2008 annual monitoring survey (in which this biotope was first recorded at a monitoring station) are listed below: Sphaerosyllis taylori is a very small mobile worm (possible predator) found in shallow water in mixed substrata. Aphelochaeta marioni is a small burrowing worm (deposit feeder) that may be common in muddy sediment with some mixed substrata on the lower shore and in shallow water in variable salinity. Syllidia armata is a very small mobile worm (predator) found in shallow water in mixed substrata. Mediomastus fragilis is a small burrowing worm (deposit feeder) found in shallow mixed substrata. Tubificoides benedii (see above)

Distribution in the estuaries The complex was recorded at one station in Group StF in 2008. In 2003, it was recorded from off Parkeston, in the outer Stour Estuary.

Appendix. 5, HHA biotope summary Page 5 of 10 Appendix 5. Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Regional and national distribution As the biotopes are not defined it is not possible to comment on national distribution.

Key species for bird feeding and bait digging Most of the species recorded are too small to be of interest to birds. Subtidal habitats are generally inaccessible to bait diggers and many birds.

Sensitivity The complex probably includes a series of transitional communities that are produced by distrurbance and likely to change with changes in substratum type and hydrology, as well as with changes such as smothering or disturbance.

SS.SMu.SMuVS.AphTubi SMu (Sublittoral cohesive mud and sandy mud communities) SMuVS (Sublittoral mud in variable salinity (estuaries) AphTubi (Aphelochaeta marioni and Tubificoides spp. in variable salinity infralittoral mud)

Biotope description Typical habitat: mud or sandy mud, sometimes with mixed substrata, in full or variable salinity, typically in the mid to lower reaches of estuaries and sheltered inlets in shallow water. Biology: infauna characterised by the small worm Aphelochaeta marioni and oligochaete worms such as Tubificoides amplivasatus. Other worms may be frequent. An average of 6,969 animals per m2 was recorded for this biotope in the richest cluster in 2003.

Typical species; top 5 species The five most common taxa recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Aphelochaeta marioni (see above) Streblospio shrubsolii (see above) Phoronis are small worms (filter and deposit feeders) that live buried in mud in sandy tubes. They may be very common in shallow water in estuaries and sheltered bays. Melinna palmata is a medium sized burrowing worm (deposit feeder) found in mud on the lower shore and in shallow water, where it may be very common. Nephtys hombergii (a type of catworm) is a large active worm (predator) that can be found in many different sediment types in a wide range of depths but is particularly common in shallow water mud in estuaries.

Distribution in the estuaries This is the target biotope for Groups StD and OrD. It is one of the principal subtidal biotopes of the estuaries, as identified by cluster analysis of 2003 data. Most of the fauna from the sediment grab samples recorded in previous surveys (Dyer, 2000) was referred to the equivalent of this biotope. Much of Holbrook Bay, mapped as intertidal in most maps and charts, fits SS.SMu.SMuVS.AphTubi on the basis of its fauna (Dyer, 2000). July 2002 dredge samples containing mud or muddy mixed sediment were assumed to belong to it. Most samples were typical of the described biotope. Certain areas proved to contain more gravel and overlap with IMX biotopes, however (Dyer & Worsfold, 2001). There was also considerable overlap with other mud biotopes.

Appendix. 5, HHA biotope summary Page 6 of 10 Appendix 5. Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Regional and national distribution This is probably one of the most widespread soft substratum biotopes in estuarine shallow water throughout the country. It is also likely to be widespread in sheltered inlets and bays.

Key species for bird feeding and bait digging Catworms (Nephtys hombergii) would be suitable for bird feed and bait if accessible. Most of the other species recorded are too small to be of interest to birds. Subtidal habitats are generally inaccessible to bait diggers and many birds.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology and to chemical contamination but less sensitive to smothering or disturbance (provided that the sediment type remains the same).

SS.SMu.SMuVS.PolCvol PolCvol (Polydora ciliata and Corophium volutator in variable salinity infralittoral firm mud or clay)

Biotope description Typical habitat: clay or peat, with mud, in variable salinity, often in the lower reaches of estuaries and sheltered inlets in shallow water. Biology: infauna characterised by the small worm Polydora ciliata, or P. cornuta, and the burrowing amphipod Corophium volutator, which may vary in abundance. Other worms may be frequent. An average of 192 animals per m2 was recorded for this biotope in 2008.

Typical species; top 5 species The five most common species recorded in this biotope for the 2008 annual monitoring survey (in which this biotope was first recorded at the monitoring stations) are listed below: Polydora cornuta (see above) Eusarsiella zostericola is a very small ostracod crustacean (clam shrimp) that was originally introduced from eastern North America and lives on and above lower shore and shallow water mud in estuaries. Nucula nitidosa is a small bivalve (deposit feeder) that may be abundant in shallow water stiff mud or clay. Nephtys hombergii (see above) Chaetozone zetlandica is a small burrowing worm (deposit feeder) that lives in shallow water in the lower reaches of estuaries and sheltered locations in mixed and muddy substrata.

Distribution in the estuaries This biotope was recorded Group OrD in 2008 and 2009. Similar communities have also been found at other stations in the estuaries (Station 290) and offshore. The fauna was variable, as evidenced by the cluster group scatter.

Regional and national distribution

Appendix. 5, HHA biotope summary Page 7 of 10 Appendix 5. Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

As the biotope is restricted to particular substratum types, it is probably scattered in its distribution around the country and may be widespread but unlikely to cover wide areas.

Key species for bird feeding and bait digging Catworms (Nephtys hombergii) would be suitable for bird feed and bait if accessible. Most of the other species recorded are too small to be of interest to birds. Subtidal habitats are generally inaccessible to bait diggers and many birds.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology and to chemical contamination. It would also be sensitive to smothering and disturbance, as these would necessarily affect the substratum type.

SS.SMu.SMuVS.NhomTubi NhomTubi (Nephtys hombergii and Tubificoides spp. in variable salinity infralittoral soft mud)

Biotope description Typical habitat: mud or sandy mud, in variable salinity, typically in the mid to lower reaches of estuaries and sheltered inlets in shallow water. Biology: infauna characterised by catworms, Nephtys hombergii and oligochaete worms such as Tubificoides amplivasatus. Other worms may be frequent. An average of 425 animals per m2 was recorded for this biotope in 2009.

Typical species; top 5 species The five most common species recorded in this biotope for the 2009 annual monitoring survey (in which this biotope was first recorded at the monitoring stations) are listed below: Nephtys (juv) most likely represents the young of N. hombergii (see above) Streblospio shrubsolii (see above) Aphelochaeta marioni (see above) Cossura pygodactyla is a very small burrowing worm (deposit feeder) found in various substrata, often in disturbed conditions. Ampharete grubei is a medium sized burrowing worm (deposit feeder) found in muddy substrata on the lower shore and in shallow water.

Distribution in the estuaries This biotope was recorded Group OrD in 2009. It was not easily recognised on the basis of 1997 cluster groups but inspection of individual sample data showed a dominance of Nephtys hombergii to be associated with reduced cirratulid (Aphelochaeta marioni) numbers. Analysis of 2003 data revealed the biotope in the estuaries (mainly in Harwich Harbour but also in the mid Stour) and offshore, mainly in Pennyhole Bay. Some 2003 estuary samples may represent an undescribed biotope related to SS.SMu.SMuVS.NhomTubi. The echiuran Maxmuelleria lankesteri was found in Harwich Harbour in July 2002 (Worsfold, 2002 – recorded as Echiurus echiurus) and may be an important food for fish (N. Britton, pers. comm.). Echiurans are known to emerge from the mud under anoxic conditions (Dyer et al., 1983). Such conditions could result from sediment dumping. The bivalve Saxicavella jeffreysii was often dominant.

Appendix. 5, HHA biotope summary Page 8 of 10 Appendix 5. Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

Regional and national distribution The biotope is likely to be widespread in shallow water mud throughout the country.

Key species for bird feeding and bait digging Catworms (Nephtys hombergii) would be suitable for bird feed and bait if accessible. Most of the other species recorded are too small to be of interest to birds. Subtidal habitats are generally inaccessible to bait diggers and many birds.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology and to chemical contamination. It is probably much less sensitive to smothering and disturbance and may represent a relatively disturbed sediment community.

SS.SMx.IMx.SpavSpAn SMx (Sublittoral mixed sediment) IMx (Infralittoral mixed sediment) SpavSpAn (Sabella pavonina with sponges and anemones on infralittoral mixed sediment)

Biotope description Typical habitat: muddy gravelly sand with pebbles, in full or slightly reduced or variable salinity, often in the lower reaches of estuaries and sheltered inlets in shallow water. Biology: characterised by fanworms, Sabella pavonina, which may form beds; epifauna, such as ascidians, sponges and anemones may be attached to the fanworm tubes. The infauna includes many small worms and crustaceans. An average of 17,089 animals per m2 was recorded in the richest cluster for this biotope in 2003.

Typical species; top 5 species The five most common taxa (other than Nematoda) recorded in this biotope for the 2003 survey (upon which the target biotopes were defined) are listed below: Sabella pavonina (fanworm, spaghetti weed) is a large worm that builds muddy tubes attached to small stones or shells that are often buried in mud. The worms have crowns of tentacles that are extended for filter feeding. They may form extensive beds in shallow mixed substrata (sometimes on the lower shore) in estuaries and coastal areas, often with strong currents. Sabelliphilus elongatus is a very small crustacean that parasitises fanworms. Syllidia armata (see above) Aoridae are small Crustacea (deposit feeders) that build tubes in mud or attached to stones, shells, debris, or other tubes in shallow water. Aphelochaeta marioni (see above).

Distribution in the estuaries This is the target biotope for Groups StF and OrC. Fanworms (Sabella pavonina) have been found in dense patches on mud or mixed substrata on both estuaries, but particularly on the Orwell (Worsfold, 2002; Jessop et al., 2003). There is also a 6ha. patch of dense Sabella pavonina on the north-western edge of the Shelf and another (3ha.) to the south, which have been mapped by towed video (Worsfold & Dyer, 2004). Much of the undredged mud to the west of Landguard Point is similarly

Appendix. 5, HHA biotope summary Page 9 of 10 Appendix 5. Biotopes recorded in the Stour and Orwell estuary annual monitoring surveys

colonised by fanworms (about 9ha.). The beds have dense Sabella and are good examples of the described biotope. Sample analysis suggests that there may be another bed off The Naze.

Regional and national distribution There seems to be little information on the distribution of this biotope nationally but it would be reasonable to expect scattered patches in many UK estuaries.

Key species for bird feeding and bait digging Subtidal habitats are generally inaccessible to bait diggers and many birds. We have found no evidence that fanworms are targeted by birds, although some of the associated species, which may include large Crustacea, could be of interest. Fanworm beds may also be important as shelter for fish nurseries.

Sensitivity The biotope is likely to be sensitive to changes in substratum type and hydrology and to chemical contamination but less sensitive to smothering, as the tubes are raised above the mud surface. Disturbance could remove fanworms and change the biotope. There is some evidence that S. pavonina has increased in abundance in the estuaries.

Appendix. 5, HHA biotope summary Page 10 of 10 APPENDIX A

WATERFOWL SPECIES ACCOUNTS 1999/2000 – 2009/10

Distribution maps of mean winter numbers for principal species from 1999/00 to 2009/10 are available in the main SWT report (SWT, 2010).

Brent goose The population has been fairly stable in the SPA at around 2000 birds since 1999, split about equally between the two estuaries in some years and alternating between them in others, although in recent winters larger numbers have been wintering on the Stour, leading to a small increase in the mean SPA population (2500 birds).

Few birds used Bathside Bay in the Stour in 2009/10, where they were frequent in the previous two winters. Otherwise, the distribution of geese has been fairly consistent between winters – concentrated in the lower reaches of the Orwell (especially Shotley Marshes and Thorpe Bay) and throughout the Stour.

Shelduck Declines in the SPA have been reversed in recent winters. Numbers stabilised on the Stour in 2009/10, where mean and peak populations were similar to those of 1999/2000. A positive trend was recorded for the first time on the Orwell owing to increases in the mean population (at 640 birds, 80 more than the previous high in 2008/09).

Birds show no particular areas of concentration on the Orwell, but on the Stour are usually concentrated in the upper reaches of the estuary, and the larger bays of Copperas, Bradfield, Holbrook, Jacques and Bathside.

Wigeon Numbers continued to decline on the Orwell in 2009/10 after sharp increases early in the monitoring programme (the population was the lowest yet recorded – mean 1183 and peak 1336 birds). The recent contrasting increase in the Stour population was tempered in 2009/10 where the mean population dropped by almost 1300 birds, although the overall trend is still one of increase.

Distribution on both estuaries has changed little – most birds frequent Trimley Marshes on the Orwell (sections 31–34), the mudflats and saltmarsh around Colton Creek, Hare’s Creek and Jill’s Hole on the southern shore (sections 24–27), with smaller numbers of birds along the Nacton foreshore (section 37). On the Stour, the upper reaches of the estuary are favoured: Jacques Bay, Seafield Bay and Mistley and Stutton foreshores, and concentrations occur consistently at the mouth of the estuary on the northern shore in Erwarton Bay (sections 37–40). Notably, birds were absent from Copperas Bay in 2009/10.

Pintail The pronounced decline in mean and peak numbers on the Stour (and peak numbers in the SPA) continued in 2009/10. In the first four winters of monitoring, mean and numbers of 300-500 birds occurred on the Stour, but in recent winters numbers have been between 200-300 birds (229 in 2009/10).

There was a pronounced change in the distribution of birds in the SPA in 2009/10. On the Orwell, birds have always been most frequent on Trimley Marshes although scattered throughout the estuary, but in 2009/10 birds occurred almost exclusively on the former. On the Stour, the main concentrations of pintail used to be in Copperas, Holbroook and Seafield Bays, but birds were almost absent from these bays in 2009/10, and concentrated on the Mistley foreshore.

Oystercatcher Mean winter numbers have been stable in the SPA since 1999/2000 at between 2160 and 2806 birds and this was unchanged in 2009/10. Similar numbers winter on each estuary and populations have been largely stable. On the Orwell, most birds winter in the upper reaches, especially along the northern (Mulberry Middle and Pond Ooze). Birds are distributed widely in the Stour, and notable concentrations occur in the larger bays.

Ringed plover Despite the slight recover in the previous winter, the trend of decrease in the SPA in recent winters (particularly on the Orwell) continued in 2009/10. A mean population of only 71 birds was recorded on the Orwell in 2009/10, and the mean SPA population of 178 birds was the lowest recorded (previous low 213 birds in 2007/08).

Birds used to be scattered throughout both estuaries, but in 2009/10 practically all birds of the Orwell occurred in Thorpe Bay and on the Pin Mill shore. Once again, birds were absent from the uppermost mudflats of the Orwell around Pond and Black Oozes. On the Stour, the only notable concentrations were in Bathside, Jacques and Holbrook Bays.

Grey plover There have been minor fluctuations in numbers on the Stour (that supports most of the SPA population), but no significant changes in the population of the SPA since 1999/2000 (there were drops in the mean population of the Stour and SPA in 2009/10 – both were the lowest recorded). Few birds winter on the Orwell compared with the Stour.

As in previous years, the distribution of birds is strongly mid-estuary in the Stour and concentrated in Holbrook and Jacques Bays, although there were notable numbers present in Bathside Bay in 2009/10 as there have been in recent winters. On the Orwell, birds used to be well-spread along the estuary, but their distribution has become strongly mid-estuary, particularly on Nacton foreshore, and notably birds were more or less absent from Pond and Black Oozes that used to support good numbers of birds (as per ringed plover).

Lapwing After recent declines in the population of the SPA since a peak in 2004/05, particularly on the Stour, both mean and peak numbers (nearly 12000 birds in 2004/2005) remained low in 2009/2010.

Despite the large variation in numbers, the distribution of birds in the SPA has remained the same and there are consistent concentrations of birds in each estuary – in Jacques Bay, Seafield Bay, around Erwarton bay and at the head of the estuary on the Stour, and on the Strand, Trimley Marshes and Levington on the Orwell.

Knot After several winters of increase on the SPA (from a mean population of 4591 birds in 1999/2000 to 11655 in 2006/2007) numbers have dropped to means of 6-7000 birds in the last three winters. Practically all this variation has been caused by fluctuations in numbers on the Stour – numbers on the Orwell have steadily increased throughout monitoring from a mean populations of 956 birds in 1999/2000 to 2268 in 2009/10.

As in most winters, birds were concentrated on the wider mudflas of both estuaries in 2009/2010: Holbrook, Jacques, Bathside, Erwarton and especially Seafield Bays on the Stour, and Nacton and Mulberry Middle on the Orwell.

Dunlin There were statistical trends in the dunlin population for the first time, although declines have been apparent on the Orwell since early in the monitoring programme. Despite this, the mean winter population in the SPA has been relatively stable as most birds winter on the Stour, but in 2009/10 this was the highest recorded (17,036 birds with a peak of 20,976) owing to the largest Stour population of the 11 winters (mean 15,370 birds). The mean number recorded on the Orwell in 2009/2010, however, was only 1665 birds, the lowest since monitoring began when 3-4000 birds were present, and is further indication of the declining status of this species on this estuary.

Birds are well distributed on both estuaries at low tide, although relatively few birds occur on the southern shores of the Orwell.

Black-tailed godwit The strong decline in numbers on the Stour noted in previous reports continued in 2009/2010, whilst numbers remained relatively strong on the Orwell. The mean SPA population fell to below 1000 birds for the first time (899 birds) and was only 567 birds on the Stour (1628 in 2000/01). Peak numbers on the Orwell (746 birds) exceeded the Stour (674 birds) for the first time.

Despite recent occupation of most of the Orwell in recent winters, the population was concentrated at the head of the estuary once again, with small numbers scattered elsewhere. On the Stour, the species appears to have become restricted to the top of the estuary, and in 2009/2010 most birds occurred on the Mistley foreshore and in Seafield Bay, with small numbers elsewhere.

Curlew No trends were apparent for curlew in 2009/10, despite pervious indications of decline, owing to increase in the mean SPA populations (primarily caused by larger numbers on the Stour). Numbers on the Orwell remained relatively low compared with early winters in the monitoring programme.

Birds were well distributed throughout both estuaries 2007/2008, as they have been in all winters, and there are no obvious changes in distribution.

Redshank There has been a strong and consistent decline in both mean and peak numbers of redshank in the SPA since monitoring began. This has been caused by declines on the Stour where the mean population has fallen from around 2000 birds to 1500 in recent winters.

Birds are well spread on both estuaries, but recent indications of a decline in use of the mid-Stour, especially in Holbrook and Copperas Bays, were repeated in 2009/10.

Turnstone Previous strong increases in the population of the SPA were not repeated in 2009/10, owing to a substantial drop in the number of birds using the Orwell (a mean of only 97 birds compared with 207 in 2004/05), but a positive trend was still apparent on the Stour.

Birds were once again absent from Pond Ooze at the head of the Orwell where they used to occur in good numbers, and they were mainly confined to Mulberry Middle and Nacton. On the Stour, distribution appears to have remained more or less constant despite the increase in population, with the primary concentrations occurring in Erwarton and Holbrook Bays.