Technical Summaries

Technical Summaries: A Guide to BORG Technical Papers and Articles

We have published over twenty scientific or technical papers and articles on the website to counter the frequently misleading claims of over-zealous conservationists. Although our papers have not themselves been peer-reviewed, they draw largely on peer-reviewed papers in the scientific literature. We list them here with a brief description for the benefit of anyone who might find them interesting or useful. All are authored by Dr Michael Simons, science specialist for BORG.

(But before delving into the technical stuff do take a look at the animated sequence showing the consolidation and expansion of the Studland Bay eelgrass beds in recent years, even as boats continue to anchor: click on . The story shown by the aerial images is confirmed by underwater videos of over 300 metres of seabed in the inshore areas, shot by Michael Simons in July 2016. They clearly show healthy, abundant eelgrass over extended areas, which include the main study areas used by the Seahorse Trust (SHT). They provide video ground-truthing for the aerial images, and graphic and actual evidence confirming the common theme of many of our technical papers, that eelgrass can thrive and flourish in the presence of leisure boat anchoring. They also show the SHT claim that the decline in seahorse numbers is due to a decline in the eelgrass habitat to be untrue. See our web page here and the more detailed paper here).

The articles are grouped into the following categories, and then ordered by approximate date of publication:

Eelgrass issues
Sea horse issues
BORG submissions to MCZ consultations
Other issues (Birds, Invasive Species, Why choose Studland?)

1. Estimating the Degree of Exposure to Leisure Vessel Anchoring                                                          (side-bar title on the website and link: Anchoring Density Analysis)

Any attempt to understand the possible impact of boat anchoring on an underwater feature must take account of both the vulnerability of the feature to disturbance and the area of the seabed affected. As we were aware of no existing published estimates of the area of seabed potentially affected by anchoring, we made estimates for Studland Bay, based on observational evidence, and also for the general case of closely packed anchoring anywhere, in which boat separation is constrained by the need to avoid collision between adjacent anchored boats. In both cases, the area affected in a boating season was low, below 0.8% for Studland Bay, and below 1.6% for the general close-packed case.


(side-bar title on the website: Studland Evidence Review Paper)

This paper critically examines point by point evidence put forward claiming anchor-damage to the eelgrass beds at Studland Bay, and also some claims made about seahorses in the Bay. It identifies two misleading arguments, one being an attempt to conflate damage caused by the repeated seabed sweeping of the chains of fixed moorings with alleged but unproven damage by intermittent anchoring. This important distinction is now generally recognised. The other misleading and false argument is claiming a false analogy between the Mediterranean seagrass Posidonia oceanica, which has been shown to be vulnerable to boat anchoring, and the very different eelgrass, Zostera marina, the seagrass present in Studland Bay and other British waters. The growth, propagation and rhizome structure characteristics of the two are entirely different, and attempts by some authors and campaigners to transfer conclusions drawn from one species onto the other species represent very poor science indeed.

The conclusions are that the hypothesis of damage to eelgrass or to seahorses caused by leisure boat anchoring is not supported by evidence, and subsequent papers and articles which are listed below continue to support these conclusions.

3. Potential for rapid recovery of eelgrass Zostera marina from short-term damage: a review

(side-bar title on the website : Eelgrass Paper)

This paper draws a distinction between long-term factors that can damage eelgrass, such as disease and pollution, and short-term factors including possible anchor damage. The former are slow to recover, but this paper highlights a number of studies in the scientific literature which show rapid (one year or less) recovery from often severe short-term damage, including deliberately raking out all plants, shoots and roots from a 2 x 2 m square, a far greater amount of damage than could be done by a leisure boat anchor. The damage was partially repaired after 1 year, the whole square was restored in 2.

It also points out that, apart from one flawed paper, there are NO scientific reports of anchor damage to eelgrass in the international, i.e. world-wide, scientific literature, despite the widespread occurrence of eelgrass in boating areas.

4. Survey and monitoring of seagrass beds, Studland Bay, Dorset
Second seagrass monitoring report
(reporting on data collected between October 2009 and October 2011)
A report by Seastar Survey Ltd. for The Crown Estate and Natural England

As stated, this independent report is by Seastar Survey Ltd.

BORG’s commentary (“Latest News, 2012) states
The key finding in a detailed 70-page scientific report released on 3rd July 2012 is that
“Currently, based on the quantitative data collected over two years, there is no consistent evidence of differences in seagrass health between the VNAZ and CTZ” (note: VNAZ is the Voluntary No Anchor Zone, and CTZ the Control Zone, where anchoring carried on as usual).
and – “There is therefore no consistent evidence of boat anchoring impacting the seagrass habitat at Studland Bay.”
The study, which commenced in October 2009 and included detailed underwater surveys over two years, was commissioned by Crown Estates and Natural England.
The study did show some differences between the two zones, and recommended continuing the survey, but in an e-mail to stakeholders from Crown Estates and Natural England it was stated
“The study took place over two years, with an option to extend it to a further year. The Crown Estate and Natural England have decided not to take up the option of funding an additional year of survey work. The voluntary no-anchor zone is no longer required for the purposes of this study therefore it will be removed as soon as possible, as stipulated as a condition of the original marine consent. “

5. Evidence Summary Nov 2012

(Sidebar title: Evidence Summary Nov 2012)

A presentation in slide format summarising BORG’s view of the evidence surrounding eelgrass and seahorses. It gives a clear summary of the essentials as at November 2012.

6. Spatial Configuration of Eelgrass in Studland Bay: a Reappraisal of Report NECR111_part_2

(side-bar title on the website: Critique of MAIA Report )

Natural England’s externally commissioned report NECR111 part 2 appeared to use dubious methodology and made some highly contentious statements about “fragmentation” of the eelgrass which were completely inconsistent with other findings in the same report. Our BORG reappraisal forensically dissects the methodology and the assertions made, and was presented to Natural England. An independent appraiser agreed with many of our criticisms, concluded that there was “biased reporting” as well as computational errors, and the report part 2 was, and remains, withdrawn by Natural England.


(Sidebar title: Aerial Image Historic Series)

A set of six aerial images showing steady expansion of the eelgrass beds from 1985 to 2011, during which period boats have continued to anchor in the Bay. (2011 is the latest good quality image available to us). This set gives a clear demonstration that the eelgrass is thriving alongside the boating activity. In May 2016 we added an animated series of aerial pictures from 2005, 2009 and 2011 which show in-filling of gaps and the shoreward movement of the inshore edge of 22 metres, a rate of 3.6 metres a year: see or the Aerial Images link above.

8. The effect of raking eelgrass as described by Boese (2002): a commentary
(Sidebar title: Eelgrass resists raking)

Boese’s paper is highly significant, as it reports rapid recovery (within 2 weeks!) of eelgrass from manual raking treatments which were far more intrusive and disruptive than an anchoring event.

9. Commentary on the MB0102 Sensitivity Matrix Assessment of Sensitivity of Seagrass Beds to Physical Damage
(Sidebar title: Critique of MB0102 Matrix)

Natural England has assessed eelgrass to be “highly vulnerable” to boat anchoring through an entry in a document known as the MB0102 Sensitivity Matrix. Examination of that document shows the assessment comes from tick-box entries based on “expert judgement from Workshop 2”. Further examination shows the “expert judgement” not to be supported by any reasons or evidence whatsoever, that those who made the assessment were anonymous and unidentified, and there was no indication that the alleged “experts” did indeed have a high level of expertise in the subject area anyway. The process was secretive, opaque (totally non-transparent) and unverifiable, flouting all the accepted norms of scientific procedure.
The BORG commentary, which runs to 17 pages, exposes this peculiar assessment and cites thirteen (yes, thirteen) peer-reviewed papers which show the assessment to be downright wrong. The assessment itself gave no references – actually, it did cite one reference, but examination showed the reference to be non-existent.

10. The Resilience and Resistance of Eelgrass to Short Term Mechanical Pressures: a Review

(Sidebar title: Eelgrass Resilience and Resistance)

A shorter version of the above concentrating on resilience and resistance issues.

11. Eelgrass and Anchoring: an Overview of the Evidence

(Sidebar title: Eelgrass Overview )

This article summarises the findings in the above papers and articles in a form which is, hopefully, accessible to a non-technical audience, representing our views as at September 2014. It explains that the observed continuing health and expansion of the eelgrass beds in Studland Bay in the presence of ongoing anchoring is explained by (a) the relatively small area of seabed actually impacted, and (b) the resilience of eelgrass to small-scale localised mechanical damage arising from its resistance to damage in the first place and its well-documented resilience, i.e. its strong powers of recovery and re-growth, a key factor which has been consistently ignored or denied by the conservationist lobby.

12. Underwater Video Sample Survey of Eelgrass at Studland Bay, Dorset, July 2016

(Sidebar title: Underwater Videos Paper)

Video was shot in five passes over a total linear distance of 300 metres. The resulting videos are publicly available on YouTube.
The results show thriving eelgrass at an estimated 90+% coverage, and provide photographic groundtruthing for aerial images which are reported elsewhere. They do not support allegations of fragmentation and loss of eelgrass habitat for seahorses, and raise serious questions about the accuracy of such reports. The evidence they give shows that the eelgrass in the area is not “highly sensitive” to pressures from recreational vessel anchoring. Assertions that damage to a “rhizome mat” causes progressive erosion of the eelgrass beds do not find any support in the photographic evidence, and the apparent good health and ongoing expansion of the eelgrass in the area suggest it is in “Favourable Condition”. The images give good views of the seabed in places, and no holes or depressions attributable to anchor effects are visible, suggesting that any such effects are reversible.

13. Eelgrass: the MarLIN MarESA Sensitivity Review in the Context of Anchoring Pressures                                                                                                                                                       (side-bar title:   New eelgrass sensitivity assessment – our view)

This new assessment of the sensitivity of eelgrass to “abrasion or disturbance of the seabed” and “penetration or disturbance of the seabed subsurface” has been published and we understand will be used to inform official “Advice” on Marine Conservation Zones. We point out that this is directed at heavy fishing gear level of disturbance (dredges and trawls) and thus is not directly appropriate to the small boat anchor level of disturbance.

14. Do seahorses favour the fixed moorings?
(side-bar title: Seahorses like moorings)

This short article points out that the Sea Horse Trust’s own evidence shows a clear preference of the observed sea horses for the edge of a mooring scar, where they can shelter just inside an eelgrass bed but with close access to some open water. Gaps in eelgrass cover seem to benefit the spiny sea horse.

15. The Great Seahorse Deception
(side-bar title: The Great Seahorse Deception)

This article starts:
“The Boatowners’ Response Group deplores the sensationalist scare tactics which
have lead to such rubbish as “Britain’s largest colony of precious seahorses has been
wiped out after their habitat was destroyed by boat anchors” – a multiple lie which appears on a number of websites.”

– and goes on to expose the untruths and deceits behind the claims.

16. Seahorse Numbers in Studland Bay, 2008 – 2013
(side-bar title: Studland Seahorse Population)

The average populations observed on any given day in 2009, 2011 and 2012 were 1.1, 0.6 and 0.9 seahorses per diving day, and the highest population on any day was just 3 seahorses. 2010 was the most prolific year, the average observed population was 3.2 and the highest was 9 on a single day. The population is highly variable and generally small, 2 or less on 85% of the days dived, and exceeded 3 on only 9% of days between 2009 and 2013. There is enough seagrass habitat for over 2000 seahorses, so any talk of shortage of habitat is plainly absurd. The arrival (or not) of seahorses in the Bay (they are summer migrants) is clearly dependant on other factors.

17. Reply to “Seahorse Trust News” Propaganda

(Side bar title: Seahorse Propaganda Response)

Response to a hysterical tirade published in the “Seahorse Trust News” February 2015

18. BORG Submissions to the Public Consultation on Marine Conservation Zones, March 2013

A. A detailed response covering Studland Bay (rMCZ 50)

B. A detailed response covering The Needles rMCZ 20, Yarmouth to Cowes, rMCZ 23, Norris to Ryde rMCZ 19, Bembridge rMCZ 22

C. A general response covering Bembridge (rMCZ 22), Norris to Ryde (rMCZ 19),
Yarmouth to Cowes and Newtown Harbour rRA (rMCZ 23), and Studland Bay (rMCZ 50)

19. Consultation on Sites Proposed for Designation in the Second Tranche of Marine Conservation Zones: Response from Boat Owners’ Response Group, April 2015

(Side bar title: Response to Consultation Tr 2 )

This response is directed mainly towards The Needles r-MCZ, for which it considers individual features including eelgrass and oysters in the context of recreational boating. It also raises questions about sites and features which might be considered in Tranche 3. It makes a more general observation, relevant to other sites still under consideration, that in the MCZ process there seems to be a disproportionate emphasis on “pressures” attributed to recreational boating – for instance in the risk assessments given for the Needles site, the minor (or even insignificant) player, recreational boating, is listed above the known major causes of marine life and habitat damage, i.e. fisheries, dredging and trawling, and is apparently assigned as causing the same level of risk.

20. Are Birds Disturbed by Boats?

(Side bar title: Are Birds Disturbed by Boats?)

Conservationists are increasingly making claims that sea birds can be adversely affected by the mere presence of boats, through “disturbance” of the birds as they go about their daily business.

This article shows through personal observation and photographs, and through many photographs and videos posted on the internet, that birds in general are rather tolerant of boats. The article lists more than 20 species of bird which may be approached within 20 metres by boats, and often much closer, without disturbing them. In our view any proposal to restrict boats from an area because of bird disturbance should be backed by evidence, including a measured distance of closest approach for the species in question.

21. Boats or Tides: Tidal Streams as Dispersal Vectors for Invasive Marine Species (July 2015)

(Side bar title: Invasive Species – Boats or Tides?)

Concern has been expressed that invasive non-native marine species might be transported from one location to another on the hulls of recreational craft. This 11-page paper considers published reports on the distribution of non-native marine species. It also considers tidal flows along the South Coast of England in conjunction with the reported duration of the mobile (larval or pelagic) phase of various species, and suggests that, over distances of at least kilometres, tidal transport may eclipse any dispersal by boat hulls, rendering it relatively insignificant. In some cases, eg the floating seaweed Japanese wireweed, long distance tidal dispersal is perfectly possible. In other cases, eg the carpet and the leathery sea squirts, non-native species have failed to spread along certain well-established yachting routes suggesting that hull-borne dispersal has not occurred in those cases.

22. Seahorses in the Poole Area 

(Side bar title: Seahorses around Poole)

Recently (Sept. 2015) published information indicates that seahorses are found at a site 4 or 5 miles out to sea, as well as at several already-known sites in Poole Harbour, in addition to Studland Bay. A local fisherman says he usually finds 20 to 30 seahorses a year in his nets (they are returned unharmed to the sea). Links are given to simulation studies and a video of the highly variable tidal flows in the area, which may influence seahorse distribution. Studland Bay is just part of the picture.


(Side bar title: Why Studland?)

This one-page flyer asks why choose one of the most popular beaches and boating destinations in Britain to be a marine conservation zone, with, as argued in the above listed articles, little or no conservation benefit?