Posts Tagged ‘habitat’

Gravel augmentation helps salmon to breed in upper Avon

A programme of gravel augmentation has been successfully carried out on the upper Avon by the Westcountry Rivers Trust, funded by South West Water, as an extension of collaborative work to improve the riparian environment for fish.   Gravel is an essential component of the salmon breeding grounds but on the Avon these breeding areas have become depleted because the natural flow of gravel downstream is interrupted by the Avon Dam.   Details of the work are available here:-

http://wrt.org.uk/gravel-bringing-salmon-back-to-devon-river/

Consultation about designating the Devon Avon Estuary as a new Marine Conservation Zone

DEFRA is consulting until 20th July 2018 about designating new Marine Conservation Zones, seeking any fresh information that might influence the decision.  The summary sheet for the Avon Estuary proposal is available here – Devon Avon Estuary Factsheet

At present, the proposal does not include South Efford Marsh or the full extension of the Bass Nursery Zone out to Burgh Island.

The ACA, unsurprisingly, fully supports such a designation and our suggested modifications as a means of protecting the marine life of the estuary from unwarranted change, development or exploitation.

Our formal response is available for inspection here :- MCZ – Devon Avon Estuary

DEFRA reply – All responses will be considered before Ministers make their final decisions on which sites will be designated in the third tranche. We aim to designated this tranche within 12 months. Final decisions on which sites will be designated will take into account any relevant information submitted as part of this consultation. We will publish details of evidence received and a full Government response to these together with the final decisions on each site within 12 months. This will be placed on the consultations section of the Government web site.

An additional rationale for designating the estuary as an MCZ was sent to Natural England in early November 2018, as follows:-
Further to my original submission about designating the Avon Estuary in South Devon as a Marine Conservation Zone or MCZ  (response I.D. = ANON- PGP8-UYCU-5), I hope it is not too late in the decision-making process to draw your attention to a feature of the estuary which I overlooked and which also was not mentioned explicitly in DEFRA’s Factsheet, although others may have mentioned it in their submissions.
This feature concerns the role of the inter-tidal salt marshes and mudflats of the estuary as important stores of ‘blue carbon’.  As I’m sure your scientists at NE will readily acknowledge, these habitats are under constant threat from sea level rise, on the one hand, and development ’squeeze’, on the other.   It becomes particularly important to conserve such carbon ’sinks’ in the face of climate change, irrespective of what individual species may dwell there. The following, italicised, passage succinctly presents  the argument for conservation; it is taken from  the website of BlueCarbonPortal.org.
‘Blue carbon’ is the carbon stored and sequestered in coastal ecosystems such as mangrove forests, seagrass meadows or inter-tidal salt marshes. These valuable ecosystems hold vast carbon reservoirs; they sequester atmospheric CO2 through primary production, and then deposit it in their sediments. In fact, most blue carbon is found in the soils or sediments beneath the vegetation.

The rates of carbon sequestration and storage are comparable to (and often higher than) the sequestration rates in carbon-rich terrestrial ecosystems such as tropical rainforests or peatlands. Unlike most terrestrial systems, which reach soil carbon equilibrium within decades, deposition of carbon dioxide in coastal ecosystem sediment can continue over millennia. However, when these coastal ecosystems are degraded or destroyed they can become carbon dioxide sources due to the oxidization of biomass and organic soil.

Because coastal ecosystems do contain substantial amounts of carbon, and because this carbon is in danger of being released, they are important in mitigating climate change. Unfortunately, however, the rate of loss of mangroves, seagrasses and saltmarshes (driven mostly by human activities) is estimated to be among the highest of any ecosystem on the planet, prompting international interest in managing them more effectively for their carbon benefits.

Although the Avon Estuary’s contribution to carbon sequestration may be small on a planetary scale, that contribution strengthens the argument for its designation as a MCZ and for the inclusion of South Efford Marsh.

 

AONB – BIOSECURITY IN SOUTH HAMS’ RIVER ESTUARIES

The ACA has collaborated with the AONB Estuaries Partnership in producing a new biosecurity plan, available on the link below, to help stop the spread of marine non-native species in our South Hams estuaries..  Please read it and take note.

The risks of an invasive non-native species in the Avon are relatively low owing to the regular flushing of the estuary by freshwater but with increases in the number of people and craft using the estuary for recreational purposes, the danger is still present.  Please be vigilant and take any relevant precautions, as advised in the plan.

The effects of invasion by Spartina or cord grass in the Avon Estuary after artificial introduction by Man are all too evident in the steady accumulation of silt and mud.   Multiplication of the Pacific Oyster outside of the farmed racks in our estuary is prevented by limiting the externally-sourced juveniles to triploid (infertile) individuals.

See the full plan here:-

Salcombe Biosecurity Plan

May 2016 – further ‘ecological’ water releases from Avon dam

Water releases from the Avon dam have been negotiated by the Devon Avon Group during dry spells of weather in order to facilitate, for example, the migration of salmon smolt.   Full details are available in Notes from the DAG meetings, elsewhere on this website.

Currently (10th May) the river water level at the Loddiswell gauging station is 0.28m – at the low end of the normal range of 0.25m-1.80m.   Therefore, the Environment Agency has triggered, with the close collaboration of SWW, the release of an extra 65ML per day of water from the dam between 3.00pm on Friday 6th May and Monday 9th May.   Most of the benefit will be in the upper reaches of the river, which for many years have run very low during dry weather.

NETTING IN THE ESTUARY – IFCA SURVEY

Devon and Severn Inshore Fishing Conservation Authority  is conducting a review of netting byelaws in our river estuaries.    If you follow the links provided here -  newsletter netting review – , you can complete a survey to provide your views about netting in the Devon Avon estuary.

I have responded on behalf of the ACA, writing, in summary, ‘Current, indiscriminate netting within the Devon Avon’s estuary makes a mockery of any attempts at balanced conservation of our river’s wildlife’.