J-JS6
TRANSACTIONS
OF
THE NORFOLK & NORWICH NATURALISTS’ SOCIETY
VOL. XX
LIST OF CONTRIBUTORS
BIRD E. C. F. BRUHN J. W. CLARKE P. R. DUFFEY E. ELLIS E. A. . . HAMOND R. . . PEATE T. U. WAIN J
Page
1
300
64
38
32
2
36
1
LIST OF ILLUSTRATIONS
(Plates are to be found opposite the pages indicated.)
Badger Deer, Red Dove, Collared Fieldfare
Flycatcher, Red-breasted Fox
Gulls at Yarmouth Fish Wharf
Hawk, Sparrow
Mouse, Long-tailed field
Nightjar
Owl, Barn
Rat, Brown
Seal, Atlantic Grey
Seal, Common
Tern, Common
Vole, Water
Woodcock and nest
Page
243
103
55
203
203
103, 242
268
129
102
64
202
176
306
307
128
177
307
INDEX TO VOLUME XX
Bird Report 1962
„ 1963
„ 1964
„ 1965
Blakeney Point, Bird Report Blakeney Point, Changes since 1953 Breckland — Bird Report Breydon — Bird Report Cley Bird Observatory — Bird Report Cley and Salthouse- — Bird Report Coypu- — -Effects of selective feeding Fenland — Bird Report Hickling — Bird Report. .
Holme Bird Observatory Holme Bird Observatory Report Horsey— Bird Report . .
Lepidoptera of Hickling Broad Light Vessel Notes Mammal Report 1962
1963
1964
1965
Marine Fauna of N. Norfolk Coast
Martins — Sand — Preliminary report of ringing
Ringing recoveries
Scolt Head Island — Bird Report
Scroby Sands — Bird Report . .
Spiders, Mass dispersal Wash — Bird Report
Page
45
115
195
254
55, 130, 206, 264
1
70, 146, 217, 275 51, 120, 198, 256 58, 135 54, 124, 201, 259 32
73, 149, 219, 278
68, 144, 215, 273
64
64, 138, 209, 267
69, 145, 216, 274
36
75, 152, 222, 280
98
174
240
303
2
300
94, 170, 237, 296
56, 131, 207, 265 50, 119, 197, 255
38
66, 141, 213, 271
TRANSACTIONS
OF
THE NORFOLK & NORWICH NATURALISTS' SOCIETY
Edited by E. A. ELLIS VOL. 20 PART 1
CONTENTS
Changes at Blakeney Point Since 1953, by E. C. F.
Bird and Juliet Wain Page 1
A Preliminary Report on the Marine Fauna of the
North Norfolk Coast, by Richard Hamond, b.sc. ,, 2
Some Effects of Selective Feeding by the Coypu (. Myocastor coypus ) on the Vegetation of Broad- land, by E. A. Ellis ,,32
Notes on the Moths of Hickling Broad, by T. U. Peate ,, 36
A Mass Dispersal of Spiders, by Eric Duffey - - ,,38
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CHANGES AT BLAKENEY POINT SINCE 1953
CHANGES AT BLAKENEY POINT SINCE 1953 By E. C. F. Bird and Juliet Wain
The outline of Blakeney Point is continually changing. The map prepared in 1946-47 (published in these Transactions, Vol. XVI, page 283) was revised by Brearley and Chisholm in the summer of 1953 to take account of the effects of the storm surge of 31st January of that year (see Fig. 19 in Scolt Head Island, edited by J. A. Steers, 1960). There have since been further changes, and in October, 1961 a new survey was carried out to bring the map of the Point up to date once more (Fig. 1).
The main shingle bank has remained in position since 1953, but Far Point has been truncated and driven back to a new align- ment, where it no longer protects the mouth of Stiffkey River. Gravel flats near the mouth of this river were apparently covered by sand in 1953, but now it is the mudflats south of Blakeney Pit which are covered by sand. Low-tide channels in the harbour have changed position, the Cley Channel taking a more northerly course, cutting back the edge of the North Side marshes and meandering close to Tibby Head, a tongue of gravel submerged at high tide.
Accumulation of inter-tidal sand-flats west of the Headland has resulted in a more northerly outflow from the harbour at low tide. The Headland has been widened by addition of low shingle ridges which have grown along the shore; and dunes have built up considerably between this shore and Great Sandy Low. There seems to be little evidence of any further westward prolongation of the Point in the alignment of the main shingle bank. In theory, the Point must have been prolonged in this alignment at intervals, in order to account for the separation of the successive recurved lateral ridges seen on the landward side of the main shingle bank.
The most obvious change in the marshlands is the spread of hybrid Spartina, which forms extensive meadows on former mud- flats and has all but displaced the patch of Salicornia- Aster marsh shown on previous maps south of The Hood. Spartina marshland is also extensive on the south side. The new survey includes low shingle banks traceable amid the south side marshes, banks which must have been built by the sea before the Point grew to outflank them and produce the sheltered environment which has encouraged the formation of the surrounding marshland.
We are grateful to Mr. K. Wass, who drafted the map here reproduced.
University College, London.
2 REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST
A PRELIMINARY REPORT ON THE MARINE FAUNA OF THE NORTH NORFOLK COAST
By Richard Hamond, B.Sc. INTRODUCTION
Throughout the history of British Marine biology the East Coast from the Humber to the Thames has always had a reputation for being a faunistic desert, inhabited by relatively few species of which many were far more abundant elsewhere. The mid-Victorian naturalists, led by Philip Henry Gosse, Joshua Alder, and others, did all their original work in places where the fauna was exception- ally rich, and in which splendid laboratories were built as a direct result of the impetus given by these pioneers. The study of life in the sea has been extremely localised ever since, so that the coasts of Norfolk and of many other counties remain underinvestigated and underrated. The results of previous workers may be summarised as follows: —
F. W. Harmer (1871) published a list of the marine shelled Mollusca.
The German survey ship Pommerania fished near the Norfolk coast at stations P.105 to 115 inclusive (see below) on the 17th and 20th of August, 1872 (Metzger, 1875).
F. W. Harmer (1884) quoted his previous list with one or two additions.
A. H. Patterson collected near Yarmouth from 1878 to 1934 (unpublished notes) and published a list of marine invertebrates (1905, p. 325) in which some of the identifications appear to be very doubtful.
S. F. Harmer (later Sir Sidney Harmer, f.r.s., son of F. W. H.) dredged in Yarmouth Roads with his father on 20. VII. 1899; among other things, according to Patterson’s notes “they secured forty species of Mollusca and several common fishes”. Some of their records were quoted by
Garstang (1900), who also quoted some of the Pommerania records (other than Crustacea) together with some unpublished records from Cromer (by H. D. Geldart) and from Happisburgh (by R. A. Todd), but none of Patterson’s records.
Stebbing (1900) quotes the Pommerania Crustacea, but not those found by Patterson, in a general account dealing with land and freshwater Crustacea as well.
Hart (1930) gave a brief description of Blakeney Harbour including the higher Crustacea (Malacostraca).
Serventy (1934) described Scolt Head Island and gave a fauna list.
REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST 3
Gilson & al. (1944) listed additions made by them to the Scolt Head fauna.
Ellis (1952) gave a general account based on the two preceding papers.
Hamond (1957) dealt with the local Hydrozoa.
Pantin & al. (1960), in a revised account of Scolt Head, gave a fauna list including all previously published records from the Island as well as the animals seen by them there in 1959.
For the adjacent counties of Suffolk and Lincolnshire the most important works are those of Morley (1934, 1938, 1941) and Young (1955) respectively.
The only offshore records are by Patterson, the Pommerania, the Harmers, and Pantin and his party. A few specimens collected by this latter group appear to be all that remains of any of these author’s collections. The present paper is based on fifteen years’ work, both intertidally and offshore, and has resulted in a trebling of the number of species of invertebrates recognised in Norfolk waters. It is hoped in future papers to deal with particular aspects of the fauna and to give some impression of the uniqueness of the Norfolk coast as regards the life below low-water mark as well as above it.
Limiting Factors in the Marine Environment
(1) The annual range of temperature is between -f-4 deg. C. in February and +17 deg. C. in September in the open sea, and between even greater extremes intertidally.
(2) The timing of the tides has a marked effect on the life of the shore; since high water of spring tides in Blakeney Harbour occurs at about 8 a.m. and 8 p.m., the corresponding low tides which expose as much as possible of the shore do so at almost the hottest and the coldest times of the twenty-four hours. As might be expected, some species (e.g. Echinus esculentus) are found only offshore in Norfolk waters, while occurring intertidally in places where the high tides are in the middle of the day and night (Wilson, 1937, p. 55).
(3) Although the principal biological indicator is Sagitta elegans ( S . setosa being apparently rare) the plankton of Blakeney Harbour and the adjacent area is poor in number of species for most of the year (probably because of the turbidity of the water and the vagaries of the sea-temperature), although some of these species, such as small calanoid copepods, may occur in huge numbers all the summer. My previous statement, that S. setosa is the only species here (Hamond, 1961) is based on misidentifications; a few genuine setosa have been taken in the Harbour within the last ten years, but these unfortunately have no date attached. In October, 1961 an immense increase in the number of Sagitta elegans taken per ten-minute haul coincided with the height of the Yarmouth
4 REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST
herring fishery; this increase was probably due to a mass of water moving southwards along the east coast (Rae & Rees, 1947) rather than to any increase of the indigenous population.
(4) The main trend of the ocean currents set up by the North Atlantic Drift is anti-clockwise round the North Sea, flowing south along the east coasts of Scotland and England until deflected by the “bump” of Norfolk, which causes the current to split in the neigh- bourhood of Cromer into two branches. Of these one proceeds east and south-east, the other turning sharply west along the coast as far as the Wash, where it turns north again and then east (approxi- mately in the latitude of Skegness) to rejoin the parent current flowing south-east at that point. Off the North Norfolk coast this westerly flow has superimposed upon it an oscillatory effect, due to the tidal cycle which in Blakeney Deeps runs in an ellipse whose long axis is parallel to the coast. If the starting point of a given body of water, at the time of low-water of spring tides on Blakeney Bar, be assumed to lie about halfway between the Bar and the Blakeney Overfalls Buoy (see Fig. 1), then three hours later (at about half flood) it will have reached the turning point at the western end of the ellipse off Wells, and in turning slows down to give about twenty minutes slack water before starting to flow eastwards again, all this taking place while the tide is still flowing hard into such nearby harbours as Blakeney and Wells. The eastern turning point of the ellipse is roughly level with the Pollard, and occurs some three hours after high water in the harbours. While the tidal ellipse is thus about ten miles long from east to west it is only about three miles across at its widest part off Blakeney Bar, this being the distance in a south-south-westerly direction of the position at high water of spring tides of our given body of water from its starting position at the previous low water; moreover, at the next lower water it ends up about one and a half miles W.N.W. of its starting point, this distance representing the overall gain per cycle. At neap tides the shape of the ellipse is very similar but all the distances covered are only about half those given for spring tides. Out near the South Race Buoy the tidal ellipse is much more nearly circular, so that it seems as if the peculiarly elongate form of the tidal ellipse inshore is due to it being “squashed” between the coast on one hand and the offshore water on the other. The strength of this tidal current is seldom appreciated until one sees it swirling past a buoy moored several miles from land, but it needs constant watching as regards navigation, while biologically its effects are threefold: —
(i) Vertical mixing is very thorough owing to the velocity of the tidal currents operating over a wide shallow area, so that there is no chance of any discontinuity layer or thermocline being estab- lished, and I have never yet found any temperature difference between the surface and the bottom. A series of bottom readings taken on 5.8.1955 read as follows: —
REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST 5
Blakeney Bar . .
One mile north of the Bar . . Two miles north of the Bar . .
17 0 deg. C. 17-0 deg. C. 16-2 deg. C.
Four miles north-east of the last position . . 16T deg. C.
which shows that, at about half-ebb of a spring tide, the rise in temperature caused by warm water pouring out of Blakeney Harbour could be detected as far as a mile off the Bar. It is possible, but not confirmed, that such a temperature boundary is established all along the coast in summer, especially in calm hot weather, separating warmer water immediately next the coast from the great body of cooler water further out. This boundary, once established, would be favoured by the shape of the inshore tidal ellipse, but rapidly destroyed by strong winds from a mainly northerly or southerly direction (i.e. at right angles to the coast).
(ii) Since the same water mass will cross a given area of sea- floor several times, in one direction or the other, planktonic larvae have a correspondingly increased chance of successful settlement and metamorphosis if a suitable substratum is present; if all the substrata are unsuitable, however, the larvae take so long to cover a relatively small net distance that it is quite possible that many of them die on the way, although some at least have a remarkable power of delaying metamorphosis (Wilson, 1937, p. 120).
(iii) In the more circular type of tidal ellipse found further offshore the speed of the current, and hence the suspended load of silt and detritus, varies very little over the entire tidal cycle, but inshore (see para. 4) each cycle will include two periods of slack water during which a part of the suspended load drops out (the densest particles first) and is picked up again in reverse order of settling as the tide gathers speed once more, though not before some of it, at any rate, has been used for food by certain bottom- living invertebrates. Ophiura albida and Anipelisca tenuicornis are the most conspicuous of these, and they should therefore be most abundant in moderate depths near the coast on suitable substrata. The truth of this can be judged from Fig. 2; the almost complete concentration in the Deeps of O. albida as against the more diffuse distribution of A. tenuicornis may be because the former is confined to relatively soft grounds where it can take advantage of a heavy “rain of food” every slack water, alternating with strong currents that sweep much of it away, while the latter, although having its greatest numbers here, can also live on harder grounds and make do with a less violently fluctuating food supply.
(5) The account by Steers (I960, Chapter IV) shows clearly how unstable the coastline is, consisting as it does of soft and loose materials (shingle, sand and mud) which are constantly being moved along the outside shore by wave action or, within the sheltered confines of the marshes, being caught in the interplay of the binding action of the various plant communities with the scouring
6 REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST
or depositing action of the tides. Moreover the entire coastline is exposed to a comparatively long “fetch” (the distance, at right angles to the coast, across the sea to the coast opposite), and such bays or estuaries as there are have only the most nominal shelter provided by the nearby land (except Wells Quay and Rocks, q.v.) so that virtually the entire shoreline is laid open to the most violent and extensive wave-action, and almost the only persistent inter- tidal habitats are those of clean sand supporting Nephthys cirrosa and haustoriid amphipods, or of large rocks, as at West Runton, which are probably too heavy to be shifted except in the most violent gales. It is interesting to note that from any northward- facing part of the Norfolk coast a line can be drawn to the North Pole without touching land.
Description ok the Grounds, and of their Fauna.
(a) Shore Grounds. These will be dealt with in the order in which they occur from west to east.
Hunstanton. North of the lighthouse runs a long narrow promontory straight out into the sea on the very “corner” of Norfolk; it is locally called “the Scaup” and is about 800 yards long at low water of equinoctial spring tides, but is almost com- pletely covered at low water neaps. The centre is composed of clay into which the unwary walker may suddenly sink up to his knees; its deceptively firm appearance is enhanced by great hillocks of mussels which form the most striking topographical feature of the Scaup. They are in fact Mytilus ediilis, but the common horse-mussel Modiolus is often cast ashore here and is also locally called “Scaup”; the old Modiolus- shells are covered with encrusting organisms, mainly the polyzoa Cryptosula and Conopeum. Both sides of the Scaup (this term meaning now and hereafter the promontory) are composed of bound shingle with black muddy sand an inch or two below the surface; the east side slopes much more gently and is a good deal sandier than the west side, and may have Ophiura albida (otherwise found only offshore, see p. 19) creeping about, covered by only an inch of water at low- water springs. On the shore immediately east of the Scaup the sandy gravel at the same level is much cleaner, and the stones are much smaller, than the bound shingle on the Scaup itself; this sandy gravel is woven through and through into a stubbly mat by the thickly massed tubes of Lanice, and strangely enough there is almost no associated fauna. At the distal (northern) tip of the Scaup certain offshore species ( Eudendrium ramosum, Halecium halecinum and Modiolus ) can be found growing in water only ankle- deep, so that they may be partly exposed; with them, the sponge Halichondria panicea forms thick felted greenish masses often over a foot across, and Alcyonium occurs on dead Modiolus- shells. On the sponge are found Bougainvillia, Archidoris, and Ophiothrix
REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST 7
fragilis, the first-named sheltering numbers of tiny pycnogons (Achelia echinata, A. longipes, Anoplodactylus pygmaeus), while the most noticeable burrowing animals are Venerupis pullastra and the polychaetes Nephthys cacea and Nereis longissima which all grow to a large size here. At times great numbers of Asterias and Psammechinus invade the shore, while the algae and hydroids that are sometimes so abundant harbour many small invertebrates among their branches. Tunicates are noticeably absent.
Under Hunstanton Pier are lumps of concrete which shelter a few animals ( Sagartia elegans, Phyllodoce maculata and Gammarus, mostly G. locusta but sometimes a few G. zaddachi ): the sands in front of the Pier have not been investigated.
Brancaster. The shore due north of the Golf Club consists of a flat expanse of clean sand sloping very gently seawards, contain- ing Nephthys cirrosa and small Bathyporeia spp., and at low-water springs many very large Tellina tenuis, Magelona papillicornis and Spiophanes bombyx, together with a few Urothoe grimaldii and occasionally Nephthys hombergi and Scoloplos armiger. At present I cannot account for the absence of Urothoe brevicornis, Haustorius arenarius and Nerinides cantabra, all of which are found in super- ficially similar shores at Wells, Stiffkey and Morston. East of this, the shore at low-water springs curves round northwards to form a broad cape on the west side of the channel between Scolt Head Island and the mainland; the sands of this cape contain moderate numbers of Ensis siliqua and one or two small Tellina, also Ophiura texturata and possibly Portumnus variegatus (only dead ones seen here) . At about mid-tide level are shallow outcrops of the submerged forest, starting approximately four hundred yards north-west of the Golf Club and running westwards for at least a mile, and consisting of about four inches of compacted vegetable remains (peat) over- lying a layer of exceedingly tenacious grey clay, from one to two feet thick or even more. Two very similar but not closely related bivalves, Barnea Candida and Petricola pholadiformis , make vertical burrows in the submerged forest; whereas Petricola never pene- trates below the peat (in which, however, it outnumbers Barnea by about three to one), Barnea goes right down to eight or ten inches below the base of the peat (i.e. more than a foot below the surface) where it attains its largest size away from competitors and predators. Old burrows of both species may have the dead shells firmly woven into place by the tubes of Lanice, usually about five or six in a single burrow, which have invaded the burrow after the occupant’s death. A third species of boring bivalve, Zirfaea crispata, is much scarcer, while small specimens of Venerupis pullastra and large specimens of Audouinia tentaculata may also lodge in the old burrows. The most conspicuous large polychaete is Nereis longissima, but the surface of peat is honeycombed with Polydora ciliata. Round the edges of the outcrops scouring by the tide excavates deep caverns in the clay, while leaving the peat
8 REPORT ON THE MARINE FAUNA— NORTH NORFOLK COAST
relatively untouched, so as to form a sort of roof from which hang small algae and tufts of Bowerbankia, the latter having other sessile organisms growing on it but not in such abundance as they do under Wells Rocks. The submerged forest corresponds to habitat “a”, and the sandy shore to habitat "o” in part, as given by Pantin & al. (1960, p. 237); they sampled the submerged forest about a mile west of the Golf Club, and not in its immediate neighbourhood as described above.
Wells-next-the-Sea. The most recent map of this harbour (Steers, 1960, p. 50) is very clear but on rather a small scale. The sands down by the east side of Wells Bar seem to be more or less barren except for a few Ensis siliqua, although higher up, on the south side of the channel opposite where a ridge drawn in red by Steers ends on the north side, there is a stony patch with moderate numbers of Lanice where systematic digging would probably reveal a few burrowing animals. The Lifeboat House (not shown on the map) is situated on the little cape which sticks out to the east at the extreme northern end of the seawall running from Wells; south of this cape, between the seawall and the channel, is a roughly triangular sandbank containing the same burrowing fauna as that off Morston Creek (see under Blakeney Harbour) except for Magelona but with the addition of Ophelia rathkei; Macoma and Scrobicularia have been found in the hard mud near the foot of the seawall, and are also very abundant across the channel north-east of the Lifeboat House.
Beyond the sandbank, going towards Wells, the channel runs close to the sea wall, which slopes down steeply into it so that its western shore is formed of large irregular boulders. Here at low tide, under rocks and on submerged rotten posts, grow large yellow masses of Halichondria (not green as at Hunstanton) and smaller masses of Ciocalypta penicillus, many orange Metridium and fewer brown ones (white ones being scarcest), numbers of the peacock worm, Sabella pavonina, and tufts of ctenostome polyzoa ( Anguinella palmata and Bowerbankia imbricata) carrying immense numbers of sessile ciliates and a few small hydroids such as Oper- cularella lacerata and Calycella hispida. The rocks are covered with Fucus vesiculosus (on which Laomedea spp. grow thickly) on top and with small red and brown algae round the sides; these small algae shelter myriads of copepods. The Quay has under it an even greater abundance of Halichondria, and more and larger Metridium, but most other species seem to be scarcer here than under the Rocks. A semi-parasitic copepod (Ascomyzon sp.) is very common in Halichondria. All round the Quay and Rocks in rotten posts the wood-boring isopod Limnoria lignorum is common, accompanied on the surface of the wood by multitudes of the tiny fanworm Fabricia sabella, and in its burrows by the ciliate Folliculinopsis limnoriae, which lives on the tail of the Limnoria itself, and by a very peculiar ostracod (probably Aspidoconcha
REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST 9
limnoriae ) which creeps about in the burrows and is found nowhere else. Wells offers an interesting comparison with Blakeney Harbour since, besides being much more sheltered, Wells has only very slight brackish influence, as shown in this comparison of the distribution of three common amphipods: —
Species W ells Quay and Rocks Blakeney Harbour
Extends in summer as far as the lowest reach of Morston Creek and on to the Strond. The dom- inant non-burrowing amphipod on the sands outside the Point. Abundant all over the Harbour, never outside the Point (N.B. — The great majority are G. z. zaddachi, some are G. z. salinus). Common in Morston Creek, es- pecially near the Quay, and on the Freshes Lays where brack- ish influence is strong; only twice found outside the Point (among debris near the Hjordis).
According to the Plymouth Marine Fauna (1957) G. locusla and Melita are truly marine species which can stand small amounts of brackish influence, Melita the more so, while G. zaddachi is an estuarine species heavily overlapping the other two at the seaward end of its range; another species of Gammarus found mainly on sandy shores in the Plymouth area is unfortunately undescribed, so that it cannot be shown if it occurs in Norfolk or not. The population of Melita in Morston Quay may well be maintained at an artificially high level by continual recruitment from the Freshes Lays, from which boatloads of mussels are brought up to Morston Quay, there to be washed, sorted and put into sacks to go by road to the markets.
Blakeney Harbour (Page 1). Biologically the Harbour, in- cluding the sands outside the Point, is one of the richest and most diverse areas along this stretch of coast, since the sandflats and creeks teem with polychaete worms of various kinds while the deepest part of the Pit regularly yields the pipe-fish Syngnathus acus, the armed bullhead Agonus cataphractus and the small spider-crab Macropodia rostratus, as well as flounders (Platichthys flesus) and in summer large shoals of whitebait (young Clupea sp.). West of the Point, on the eastern edge of Stiffkey Sands, lies the wreck of the French schooner Guenowle which came ashore in 1921; and north of the main sandhills squarely in the middle of what was the main channel until 1960, lies the “Iron Steamship” (the local
Gammarus Abundant at all locust a times of year.
G. zaddachi None at all so far.
Melita Abundant.
palmata
10 REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST
name for the wreck of the Norwegian coaster Hjordis, which ran aground there in a storm in December, 1914). Although gradually decaying, the Hjordis is still the finest natural grotto imaginable, full of sessile invertebrates. Below decks the dominant attached forms are the false coral Alcyonium digitatum and the sea-anemone Metridium senile, while the hydroids Tubularia larynx, Halecium lankesteri, and Plumularia setacea, the polyzoa Bugula plumosa and Scrupocellaria scrnposa, and the tunicates Didemnum candidum, Sidnyum turbinatum and Botrylloides leachi all carpet the sides, and a few can usually be found of the following: — the hydroids Bougainvillia ramosa, Coryne muscoides, and Sarsia eximia, the sponge Leucosolenia (most if not all L. complicata) , the nemertine worm Lineus longissimus, the brittle-star Ophiothrix fragilis (often extremely abundant on the inside walls of the wreck), the hermit- crab Pagurus bernhardus, the edible crab Cancer pagurus and the lobster Homarus vulgaris. On the colonies of hydroids and polyzoa are found numerous free-living animals such as the amphipods Caprella linearis and Jassa falcata, the pycnogonids Achelia echinata, A. longipes and Phoxichilidium femoratum, various marine mites (mostly Copidognathus spp.), the polychaetes Lepidonoius squam- atus, Autolytus spp., Procerastea halleziana, Polydora ciliata, small Sabella pavonina, Pomatoceros triqueter, a few terebellids, and abundant Protozoa (vorticellids and suctorians). The broken-off base of the mast is riddled with Chelura and Limnoria. All these species live inside the wreck; outside it, round under the stern and rarely elsewhere, are numerous fig-like colonies of the tunicate Aplidium proliferum, belonging to a local variant that constantly has eight instead of six lobes to the branchial siphon, while the outsides of the wreck are covered with a thick felt of green algae ( Enteromorpha sp.) among which the cottony tufts of the hydroid Laomedea dichotoma var. plana show as dull white or brown, and which looks invitingly smooth until the collector’s hands and knees are tortured by the sharp points of myriads of barnacles just underneath. On top of the decks the amphipod Jassa falcata builds its muddy nests in enormous numbers among forests of small red algae, and clumps of mussels hang from the beams. Guenowle used to have a similar but less rich fauna in which Metridium, Tubularia, Scrupocellaria and Bugula were dominant, but since 1954 there have been extensive changes (probably as part of the aftermath of the 1953 flood) so that Stiff key Sands has advanced about twenty or thirty yards eastward into the channel, completely surrounding Guenowle of which only a little piece now shows. The mouth of the channel down towards the Bar, which in 1945 to 1948 ran about two hundred yards west of the Hjordis, has moved east every winter so that, whereas only her stern stuck out into the channel in 1952, since 1954 it has been impossible to board her except from a boat at low tide, a perilous undertaking in any but the calmest weather. In 1960, however, a new channel opened up
REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST 1 1
about half a mile west of the old Bar and communicated with the old channel about halfway between the two wrecks; this has now deepened to form the main channel, much larger than that going round by way of the Hjordis, a few yards east of which (and at present submerged) lies some remains of a double-walled wooden smack, which sometimes contains hydroids and tunicates. The tideline near all these wrecks is an excellent place for animals which have been washed up, but it is not always possible to determine whether they came from the Hjordis or the seafloor outside; cork buoys moored in the channel become covered after a time with algae above (harbouring Jassa and Gammarus locusta) and Tubularia larynx below, on which aeolids feed.
Heading south-west from the Hjordis towards the Far Point, the shore used to be of clean sand that held a high water content even when exposed for a few hours at low-water springs (its own level being slightly above low-water neaps) due to its being very flat and sloping evenly from the edge of the shingle spine of the Point all the way down to low-water mark, so that the water- table was almost parallel to the surface and never very far below it. At high water the shingle, being battered by waves, takes up water like a gigantic sponge, and continues to discharge in the form of small rivulets across the surface of the sand long after the tide has receded. Since 1957 the proportion of shingle has greatly increased (caused possibly by the removal of much of the sand rather than by the addition of more shingle) and the distinctive burrowing fauna of worms ( Nephthys cirrosa, Nerinides cantabra) and haustoriid amphipods has dwindled to a fraction of what it was in its heyday, when the patch containing them covered an area of less than two acres, surrounded on all sides by a vast expanse of apparently identical sand in which they were scarce or absent; they are still common near low tide in the sand lying off Stiffkey and Wells.
The Far Point is connected to the mainland immediately south of it by a wide belt of stones resting on hard clay, of which a part (a tongue-like promontory stemming from the southern shore) is exposed at low-water springs, and is called the Reef, while the other part, the Threshold, is always submerged by the swiftly flowing current emptying the Sin Pool into the lower channel running down past Guenowle to the Bar. The Threshold is covered with large brown seaweeds ( Laminaria saccharina and Chorda filnm, both restricted to places with fast current flow and limited wave action); Lamiwan’a-holdfasts contain a rich assemblage of small invertebrates from which, however, tunicates and shelled molluscs are conspicuously absent. The Sin Pool has not been fished in; at low tide the Pit drains into its north-east corner, and the Stiffkey River (with some addition from the Pit) into its south- east corner; this latter channel, although still the smaller of the
12 REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST
two, has widened and deepened very considerably since 1958 due to the rapid erosion of the hard clay which forms its south side. In between these channels lie the Freshes Lays, a hard stony and muddy patch covered with mussels which are cultivated here; young mussels transplanted here from the Wash often contain the peacrab Pinnotheres pisum, which never survives for long, perhaps because of the wide daily variations in salinity and temperature. Medium-sized Venerupis pullastra are quite common, and in winter Aeolidia papillosa, in spring Onchidoris fusca, are plentiful along with their egg-ribbons, though both these sea-slugs have been found spawning here as late as the first week in June. Of the algae, Laurencia is abundant in little pools on the lays and gives shelter to myriads of harpacticids and to much larger numbers of the viviparous brittle-star Amphipholis squamata than can be found anywhere else, although this is a common species under stones all over the western part of the Harbour. The shelly grit, with plenty of mud in it not far below the surface, which forms a large proportion of the northern half of the lays is an excellent ground for polychaetes, especially Lanice conchilega but also Audouinia tentaculata, Notomastus lalericeus, and occasionally Tharyx marioni and Kefersteinia cirrata, while deeper digging in the thick black mud underlying the lays may give Nereis virens and large Amphitrite johnstoni. Under stones on the surface can be found Gammarus zaddachi, G. locusta, Melita palmata and rarely other amphipods, the chiton Lepidochiton cinereus, and the polychaete Phyllodoce maculata which may be especially abundant on the Sin Pool shore of the lays. Almost the only hydroid in winter, and by far the most abundant in summer, is Laomedea dichotoma var. plana, but Kirchenpaueria pinnata is also common here in summer, as is Laomedea flexuosa on Fucus near the mouth of the Freshes, whereas Tubularia larynx, Campanularia Integra, and Plumularia setacea have each occurred once only. Hydractinia echinata was once (ca. 1951) not uncommon here on shells of Buccinum undatum tenanted by Pagurus, but is nowadays most often taken in whelk pots out to sea. At or slightly below low-water springs one or two small colonies of the typically offshore hydroid Sertalaria argentea may be found; Clytia johnstoni grows on it, also on Ceramium rubrum and Ulva lactuca on the Reef and the lays. Polyzoa include Conopeum reticulum and Electra pilosa (both very common), Cryptosula pallasiana which was plentiful here up to about 1956 but has since died out almost entirely (though still very common at Hunstanton and West Runton), and Alcyonidium mytili, amongst others. The endoproct Pedicellina cernua is common on algae and on hydroids, whilst its relative Loxosoma singulare occurs, sometimes in large numbers, on the polychaete Notomastus. The anemone Sagartia elegans is most abundant in the Threshold but is also quite common under mussels on the lays; a larger species, Tealia felina, is only rarely found here.
REPORT ON THE MARINE FAUNA — NORTH NORFOLK COAST 13
On the eastern half of the Strond (the “South Side” of Steers’ map), which extends between mid-tide level and high water of neap tides, there were, up to about ten or more years ago, large mudflats covered with wigeon-grass [Zostera spp.) which have since been greatly reduced by the phenomenal growth of Spartina townsendi. This pestilential plant covers the entire upper part of the shore on the west side of Morston Creek, from which it extends westward on both sides of the Zostera, covering Seven Foot Knoll on the one side and the entire frontage of the Meols on the other, the latter as far west as the shingle spit running out to the Freshes Stake. This spit is the most prominent part of the immense tract of shingle covering the whole western half of the Strond; there was formerly much more sand just east of it than there is now, but the flood of 1953, and the altered tidal conditions after it, removed much of this sand and deposited it on the Freshes Lays and else- where. In the north-east corner of this shingle area a large shallow artificial pool has been formed during the last three years, due to the building on its north side of a dam, about a foot high, made of planks backed with stones, through whose interstices water drains off continuously from the pool; these interstices support a sur- prisingly rich fauna for such an exposed habitat, so high up the shore. East of the Strond Pool (in which mussels are kept for fattening) the Strond consists mainly of hard clay, on which the Spartina grows directly, or which may be covered with muddy sand; a bank of clean sand has grown up remarkably in the last four years on the edge of the Strond next to the Pit, a little way west of Seven Foot Knoll. The fauna of the Strond is less restricted than it might appear, since most animals must be dug for in muddy sand or searched for under stones or among algae; the commonest