Adverse changes to the sea bed, flora and fauna of Whitsand Bay

The changes to the sea-bed and impoverished flora and fauna in Whitsand Bay, shown in Dave Peake’s underwater video are of great concern.  Such large changes can be very difficult to undo as complete sections of the complex, interactive biological community may be wiped out, removing the organisms which will be key in re-establishing any semblance of a diverse, healthy marine environment.

In particular, the build up of bacterial mats is very worrying as this is an indication of things going seriously wrong, which will take very long periods of time (and perhaps a lot of costly human input) to reverse.  Beggiatoa lives in rather extreme environments and once established, tends to dominate to the exclusion of a most other organisms, especially the more complex and varied flora and fauna such as seaweeds and fish.

Beggiatoa is an indicator of an uncharacteristic shallow-water environment and a marine biological community under extreme pressure.
 

Beggiatoa obtains its nutrition by some fairly unusual biochemistry.  Some other mud-dwelling organisms, can similarly have some unexpected, complex biochemical pathways some of which can change relatively inert substances such as trace heavy metals into some rather unpleasant organic ones which are much more reactive.  These can build up in the food chain and present a risk to higher organisms and eventually humans if eaten.

More on Beggiatoa
 

Unpleasant though Beggiatoa is, Silt build up is the most likely underlying cause of the problems developing in the Bay and its effects are more insidious and much more difficult to reverse.  

The turbidity (cloudiness) within the water cuts out sunlight leading to poor or negligible plant growth.  As the plants die and rot, they add to the demands on the oxygen in the water, making it more anoxic (lacking in oxygen).  This inevitably leads to the loss of the many organisms in the marine community which rely heavily on well-oxygenated water for their health and survival.  

Many animals within the marine community (e.g. shell fish) rely on filtration of large quantities of sea water to extract their food.  Suspended silt (even if non-toxic) can give an excessive load on their filter mechanisms, leading to poor efficiency and starvation.  Death and decay will again increase the anoxic environment. 

Polhawn Cove presents a rather sheltered, protected marine environment for the organisms which live there, perhaps making it more fragile than if it was more exposed in the open sea.  It probably presents a high-risk area for silt build up too: wind-mixing is relatively subdued as the cove acts as a sheltered cup with high cliffs to the north and east giving some wind-shelter.  Tidal mixing is also relatively slight in the cove for similar reasons – the cliffs provide a tidal trap at the end of the larger sweep of Whitsand Bay. 

 It should be noted that , even if the material released in the dumping zone is entirely non-toxic (which is open to question), from a biological viewpoint, the siting of the dumping ground is unsuitable for the disposal of silt. It is too shallow and too near to the sensitive marine communities in the shallow, shore waters of the Bay.  Although perhaps suitable for large, inert debris and waste, in days gone by, the finer particles of more recent dumping programmes are much more biologically active and are likely to continue to drift in and build up in the delicate sheltered environments nearer the shore.  This will inevitably lead to continuing degradation of the environment, death of the organisms living there and consequent reduction in the bio-diversity and economic value of Whitsand Bay.

If contamination was found to encroach onto the beach, or local fish or shellfish were found to be affected, the effects on tourism and thence the local economy, would be dire and rapid in these times of keen, widespread media interest.