This paper not to be eited without referenee to the author.
International Couneil for C.M. 1981/L:37
the Exploration of the Sea 8iologieal Oeeanography Committee.
Observationson blooms oF Noetiluea of the south eoast of Ireland
during summer 1977
by 1 1 Miles Parker , Dan Minehin , p.J. Ga~land2 and Paul Connolly1.
1 Fisheries Research Centre, Abbotstown, Castleknock, Co. Dublin.
2 Sherkin Island ~arlne Station, Sherkin Island, Co. Cork.
Abstract
Red water assoeiated with blooms of Noetiluea seintillans
(MeCartney) Ehrenberg oecurred along the south eoast during
Jul~ and August 1977. Small, 10ea1 blooms oeeurred inshore at
several points and extensive oFF-shore blooms oeeurred briefly
during August. The oeeurrenee of Noetiluea at Lough Hyne
(Ine) and Sherkin Island, County Cork, i5 r~ported in more
detail. Comparison is made with other reported oeeurrenees. , Resume
./ Des Eaux Rouges, aSSOClees avee des proliFerations anormalles • de Noetiluea seintillans (McCartney) Ehrenberg, se sont produltss sur la eote sud d'Irlande au cours des mois de Juillet et
/ d'Aout 1977. Des petites proliferations l~cales se sont
produites sur 1e littoral en difFerents points et quelques
proliF~rations de courte durcie se sont produites au 1arge au
cours du mois d'Aout. La pr;sence de Noetiluca ~ Lough Hyne
(Ine) et ~ Sherkin Is1and, en County Cork, est decrite en
detaIl." . ,,,-; , " -1- ( ...
Introduction In 1976, a bloom oF Gyrodinium aureolum Hulbert on the south
coast of Ireland caused mortalities oF littoral Fauna and
demersal Fish (Ottway ~.~., 1979). Subsequently, it was
decided that observations on similar oocurrences should be
collected by the Fisheries Research Centre; this paper
presents three sets oF observations made on blooms during
1977. Thece are, Firstly, a compilation oF reports From Fishermen and others of the incidence oF 'red tides' and oF
the results oF examination oF water sampies sent in by these
observers; secondly, data on hydrography and plankton
distribution in Lough Hyne (Ine), Co. Cork, where a Fisheries
Research Centre project on collection oF Pecten maximus spat
had been in progress since 1975; thirdly, similar observations
made in the vicinity of Sherkin Island, Co. Cork where a These study on Crassostrea ~igas growth was in progress.
observations were gathered by MP, DM & PC, and PJG
respectively.
• Coastal sightings of discoloured water.
Figure 1 shows the south and southwest of Ireland; numbers on
the map indicate sightings referred to in the text.
Red water was first observed in the vicinity oF Helvick Head, ( 1 ) A patch of rliscoloured south oF Dungarven on 14 Jul y. water was observed which moved to a point about 5 km south
oF the head the Following day and was observed further west • -2-
on 16 July. ~reshening south westerly winds appear to
have dispersed this patch by 17 July. Several patches
of discoloured water were observed in Youghal Bay(2) on 15 and 16 July and water in neighbouring Ballycottin (3) Bay was reported to be 'slimy' during this period.
Between 15 end 17 July a patch of red water was noted off Aoches Point(4J.
There was only one report of red water (from Knockadoon
Head(5) on Youghal Bay on 1 August) between 17 July end
8 August. Subsequent reports were from further south end west than the July events.
On Band 9 August a very extensive series of offshore dis-
colouretiorewas observed by the pilot of a helicopter
servicing the Kinsale Head Gas Field Platforms and by an
Irish Air Corp pilot on a routine flight. Their flight
paths, in the area where they observed red water are marked
on Figure 1 together with a point at which a fishing vessel r6il~b,c) off Kinsale noted red water on 8 August •
A week later (15 August) two further reports of patches of red water were received from a fishing boat near the Old , (7] Head of Kinsale and the pilot of a commercial aircraft en route from Cork (8]
Further west, patches oF discoloured water were observed in Ounmanus Bey(9) on 8 and 9 August; subsequently on
23 August very dense patches of red wa~er occurred in the -3-
bays of the north side of Ounmanus. Observations in Lough
Hyne and Roaring Water Bay are reported later in this paper.
Water sampies were taken at Helvick (14 July), Youghal
(1 August), Kinsale [8 and 15 August) and Ounmanus (23
August) in addition to those taken in the Loch Hyne and
Sherkin Island Studies. In all cases the dominant organism
was noted to be Noctiluca ~cintil13ns (McCartney)
Ehrenberg; the state of the sampie from Ounmanus would
suggest that the bloom was at that time moribund or decaying
in that area. Other organisms in the samples were not
identified but none were noticeably abundant.
It seems Iikely that Noctiluca was the organism dominating
all the observed blooms. They were all described as being
orange to red in colour and as occurring in patches or long
slicks. One report, from salmon netsmen suggested that
the visible effects did not extend further than about 1
metre depth.
• Weather data for this per iod from the three south coast weather statiorlS [Rosslare, Roches Point rCo~~j Rnd Valentia
Island) was examined. That From Roches Foint is presented
in Figure 2; the data from the other two stations does not
differ greatly and indicates the same pattern of events.
Wind strength was variable, beirg close to the 30 year average
in July but lower in August. However, blooms occurred _4_
during, or just aFter, periods oF low wind speed, and dis- pers~cl as wind speed rose. The apparent exception to this rule is the appearance oF red watp.r in Ounmanus Bay on 23
August; however, in this case it seems possible that relatively strong southerly and south-westerly winds caused inFluxes of moribund blooms to the north side oF the bay.
On most oF the other occasions, the winds were onshore or along-shore, From an easterly quadrant.
RainFall throughout the period was very low until aFter the last bloom. There was no obvicus correlation between the • Few showers that did occur and the appearance oF red water.
On the other hand, there was generally rather more sunshine than the 30-year average during this period. Air temper- ature was close to normal For this time oF year.
Tidal height data For Cobh, Co. Cork, is given as being indicative oF the occurrence oF spring and neap tides and hence oF the strength oF the tidal stream. It may be noted that, while the inshore blooms occurred at or beFore spring tides, the extensive ofFshore bloom occurred at the • lowest neap tides of this per iod.
The occurrence oF Noctiluca in Lough Hyne
Oiscoloured water was observed between the end of July and mid August, ~ostly on the northern shore of the lough (Fig.5).
Ouring this time observations on plankton and hydrography were being regularly müde at a single station (station C oF Bassindale et al., 1957) in the northern basin of the lough, -5-
though discolouration was not observed at the sampling point.
Methods
Oally vertical plankton hau's were made From 20m to the
surFace and the sampies were examined under binocular
microscope; order-of-magnitude counts (as tensthundreds,
thousands, greater than thousands per cubic metre) were made.
On the night oF 10 11 August, these were supplemented by
pumped sampies taken at depths oF 0.1m, 5m, 10m, 15m and
20m at 1800hrs BST, 2100 hrs, Midnigh~ and 0300hrs • • Water temperature was measured daily to 0.05o'C with calibrated reversing thermometers mounted on a Nansen bottle. Water
transparency was estimated with a white 32cm diameter Secchi
disco RainFall measurements (in mm) ware taken near the
north-west shore oF the Lo~gh From a rain guage; insolation
was estimated in terms oF sunshine hours/day and wind strength
was visually estimated From water surFace conditions
according to the BeauFort scale.
Observations • Weather data is present~d in Figure 3, together with estimat- ions oF Noctiluca abundance From the vertical hauls.
Noctiluca was First observed on 29 JulYi numbers at the
sampling station ex~eeded one thousand per cubic metre
between 6 and 14 August. Wind speeds were low during
the First halF oF August and insolation was high: the Lopgh
was thermally stratiFied (Fig. 4). Secchi depth decreased
From 22 July to 3 August but thereaFter increased agaln. -6-
From mid August numbers oF Noctiluca declined though there was a slight increase around 28 August which persisted for about a week. Noctiluca ceased to be recorded in the plankton on September 14. At the sampling station,
Noctiluca was most concentrated between the surFace end ten metres at night with little or none occurring below
15m (Tab1 e 1).
TABLE 1
Numbers oF Noctiluca at diFFerent depths during the night of 10 / 11 August. •
3 Numbers oF ~octiluca in 1000s/m (% total)
Time
Oepth (m) 1800 2100 2400 0300
0.1 14.4(20.3) 19.8(21.7) 26.0(36.5) 24.3(22.5)
5 29.0(40.9) 43.5(47.6) 23.1(32.4) 17.0(22.5)
10 15.7( 22 .1 ) 20.4(22.3) 22.1 (31 .0) 40.5(37.5)
15 11.8(16.6) 7.6( 8.3) O.O( 0 ) 20.3(18.8) 20 O.O( 0 ) O.O( 0 ) 0.2( 0.3) 5.9( 5.5 •
70.9 91.3 71 .3 108.0
From late July to mid August, orange discolouration oF th. water was noticeable at the north shore, especially on the rising tide; brilliant luminescence was noted at night.
This discolauration extended along the share line in a narrow r I -7-
CO.5m) band or occurred in the open water in elongated
patches up to 60m long. Oiver observation showed that
visible effects were limited to the first metre depth.
As the bloom declined after 14 August, a thick scum occurred
in the north shore accompanied by a strong smell of decay.
The visible effects probably resulted from the action of
light onshore winds.
The occurrence of Noctiluca off 5herkin Island, Co. Cork.
Ouring the summer of 1977, hydrographie measurements and • observations on the plankton were routinely made at three sites (Kinnish Harbour, the Dock a~d ~ones Island, Figs. 5
end 6). These sites were originally chosen in relation to
their suitability for oyster culture and hence were in
shallow water.
Zooplankton populations were sampled by a standardised four'
minute surface tow with a 1m diameter zoo-plankton net.
Calibration with a flow meter showed that each tow filtered
+ 3 • 6.5 - 1.23m of water. Numbers of zooplankton (and Noctiluca) were counted on a Bogarov tray under a binocular microscope.
Phytoplankton sampies were collected from 30m depth by
pumping 100 1. of seawater through a 20~m mesh net.
Following fixation with Lugol's iodine, samples were examined
on a haemocytometer slide at 400 magnifications.
Seawater temperatures at 30cms depth were measured daily at
Kinnish Harbour end Truhane Point and weekly et the Dock end
Jones Island, using a sea-wnter temperature bucket. Weekly -8- " ....
sampies of seawater were taken at high tide from a depth of
30cms using screw cap pQlythene containers. Chlo~ophyl a
concentrations were determined photometrically by a method
of Strickland and Parsons (1968). Weather data was obtained
from the Sherkin Island Field Study Centre, except wind
data which may be taken as comparable to that at Roches Point
or Valentia [Fig. 2). Maximum end minimum air temperatures,
as weIl as sea temperatures, peaked during mid-August after
a cooler finish to July. Insolation was variable; Rain~all
was high only towards the end oF August and this resulted In
a lowering of salinity at that time. July was above ..
averagely windy, while August was generally calm until the
end oF the month. Hydrographie data is presented (Fig. 6)
only from the Kinnish Harbour which has been found to be reasanably representative of the area. Salinity [measured by hydrometer) and transparency (measured by Secchi disc, in deep water adhacent to the sites) was also measured.
Salinity varied little, remaining around 34%.except after th~ rains at the ~nd oF the month when a gereral decline to 31~occurred (26%oat. Jones Island). Similarly, transparency .. though variable remained at around 3m secchi depth during
August (though deeper and more variable at the Dock). becoming shallower after the rainy per iod. Neither parameter shows obvious correiation with the bloom, though there was a decrease in transparency in early August as compared to
July.
~,smail patch oF discoloured seawater was observed off Sherkin
Island at Truhane Point on 18 August. Subsequent examination ...." .~ -9-
" ' " t·
showed this to contain large numbers oF Noctiluca. On the
evening tide oF 20 August, bright luminescence was obse~v.d
at Kinnish Harbour; salmon Fishermen also reported particulsrly
bright luminescence south oF Sherkin and Cape Clear. Pa1:ches
oF discoloured water were noted in Ounmanus Bay, end Roering
Water Bay (between Schull ~nd the CalF Island).
Nocti luca was First "'ecorded in plankton sampies on 10 July 3 .. in numbers less than 1000/m ; by August 5 this had changed 3 little, around 1-2000/m being recorded. However, on 15 3 ' 3 August numbers had risen to 5500/m at Jones Island, B5DD/m 3 at Kinnish Harbour and 15,000/m at the Dock. At the next
sampling time (26 August), numbers had declined to less than 3 3000/m and this decline continued until mid September when
none were recorded (Fig.6). ~hlorophyl levels (Fig. 6) :
were low in July, but per:3ked during and aFter the Noctilue.·.. ·
blooms .
• Other dinoFlagellates were also common at this time, part- icularly Peridinium granii, P. divergens, Ceratium candelebrum
and Gonyaulax sp. (probably G. polyedra). UnidentiFied
GymnodiniForm species were also present. Table 2 indicates
relative abundance oF these and other common phytoplankters. -10-
TABLE 2: Results of Phytoplankton surveys in Roarlng Water Bay.
LOCATION KINNISH DOCK JONES ISO ...... Ql >. . ~ ~ Ql >. . . ~~ Ql >. .. ~ ~ c~ m m a.a. c ..... rn rn a.a. c .... rn rn a. a. OINOPHYCEAE (excluding ., :J ::J :J G.l Ql ~., :J :J Q) Ql ., :J :J :J G.l Ql Noctllüca sp. Je:( e:( mm e( e( mm Je( e( m m mo 1Il 1Il I' 0) no 1Il 1Il 1'0) m OlIl l!l I' m ~ ~ ... ~ ~ ......
Peridinium grani i OstenFeld A A R A Perldlnlum divergens Ehrenberg C C A Ceratium candelabrum Ehrenberg A C A Ceratium tripos o. F • Muller C R C A Ceratium Fusus(Ehrenberg) C ., g Gonyaulax spp. C C C • Gymnodinium spo. R R R , R Prorocentrum spp. C ., C UnidentiFied I dinoFlagellates R C R OIATOMACEAE Coscinodiscus spp. C R CC AA :, A C AA CCC CA A Thalassiosira spp. CRC AC CC Rhizosolenia spp. g CC C CCCC R CR C R Oltylum brightwelli ( \-.jest . .) C C g C Skeletonema spp. R =t CC A C A CC C CCA A Leptocylindrus spp. C CCC CR A C Chaetoceros spp. CC A A A 11 C 9 A A A R Melosira spp. R A R • Paralia spp. R Nitzschia spp. R ACC A A AC I Asterionella japonica Cleve and Moller CC C A Halosphaera spp. R Pleurosigma spp. C A A R R R R C Navicula spp. C A A C R R 8 AC C A C CC Phalaeroma spp. C C Unidentified diatoms R A CC A C
OTHERS Isochrysis spp. A UnidentiFied Flagellates A A 11 R A R A A R
A = Abundant, B = Comman, R = Rare ...... ------
-11-
Oiscussion
Noctilucü is ~ega~ded as a common ~ed-tide o~ganism (ICES,
1976) . It 1s possibly too common to ~epo~t except in
exceptional ci~cumstances; the~e a~e Few ~ecent ~eports oF
Noctiluca btooms in European waters and these mostly reFer to
exceptionally extensive blooms. Kat (1979) in the course
oF eJ paper on Prorocentrum notes that "o~ange-reddish coloured
wateI""" is F~equently observed on the Dutch coast in summer
and that in 1971, a mass-development oF Noctiluca occurred • lasting From MeJy to August. Le Fevre and Grall (1970) report on extensive blooms on the west coast oF Brittany in
July 1967, associated with the GDI".Irrgence oF mixed coastel
waters with stratiFied estuarine-type waters in the Iroise
Sea. Interestingly, at a second Frontal system, the tidal
mixing F~ont oFf Ushant, blooms ware not noted. Pingree
et al., (1975, 1976, 1977) have noted tha tidal mixing
F~onts to be important sites oF red tide development both
oFF Brittany and elsewhere in the Celtic Sea; They however
p~imarily associate these systems with the development of
• blooms oF Gyrodinium aureolum, rather than Noctiluca which
they consider to be an inshore bloom former. Noctiluca
has been observed to bloom regu"larly on a small scale in
the Eastern Irish Sea; Evans [1977) obse~ves theJt numbers oF
Noctiluca we~e lower in 1977 than in 1976 in this area.
This is the only occeJsion to date on which Noctiluca blooms
have been recorded from the Irish south coast though bio
luminescence in summer due to Noctiluca 15 commonly observed. -12-
The blooms Fall into two e~tegories, ~amely the small seale
10eal pntehy blooms oF July in the Youghal area and August/
September in the Southwest, and the very extensive oFFshore
blooms oF 8 - 9 August.
The laLter may in Fact have been assoeiated with a tidal
mixing Front. Sinee the Celtie Sea is stratiFied throughout
~ the summer rCooper, 1967; Pingree et al., 1976), a tidal
mixing Front will oeeur alonq t~e lenqth oF the south eoast. These bInoms oceurred nFt~r aperiod oF spring tides and • higher than nverage wind speeds gave way to aperiod oF
relatively ealm sunny we~ther and partieularly low amplitude
neap tides. In this shortlived period oF exeeptional
stability it is possible that the neutrally buoyant Noetiluea,
aided by eonvergenee and the action oF light breezes eould
have been Formed into the extensive series oF slieks observed.
This would appear to presuppose that Noetiluea numbers were
already high and required only a eombination oF ealm and a suitable coneentrating meehanism For a bloom to oeeur. • There is- some evidenee For this viewpoint From the Lough Hyne
and Sherkin Island data, both dF whieh showed Noctiluea
numbers increasing during the period at whieh blooms were
observed in that aree even though blooms did not oeeur at
the sampling sites. In Lough Hyne, the visible surFace
eFFects appear to have resulted Fram cancentratian by light ( winds an or near the shoreline.
Similarly, the eFFeets oF ealm eonditions and localised -13-
eoneentrating meehanisms aeting on raised population oF
Noetiluea eould aeeount Far the more loeal inshore patehes oF
red water. Personal observation (MP) at Knoekadoon and
Helviek suggests that small seale eonvergenees oeeur around
these headlands at eertain times, possiblyrelated to tidal
eurrents; these are visible From the headlands as distinet
boundaries between water bodies oF diFFering water eolour
or surFaee eondition. The blooms invariably oeeurred in
periods oF bnlow average winds and rapidly eleared up when • wind speeds rose.
These events may be eompared with other oeeurrenees oF red
water in previous and subsequent years (Ottway et al., 1979;
Parker, 1981 and unpublished dataJ. A pattern emerges oF
red water events oeeurring earliest in the eastern part oF
the south eoast (~une - ~uly) and extending later (August -
September) to the south west . In most years, the Youghal.
area has been the First From whieh red water has been reported;
usually this has been assoeiated however with diatom blooms • (Ottway and Parker, in prep. and unpublished reeords). Roden et ale [1980J also peintm a sueeession oF sub-visible
diatom blooms in the south wes~ beFore dinoFlagellate blooms oeeur; in most reeent years, the dinoFlagellate blooms have been oF Gyrodinium aureolum; it is interesting that
Evans (1977J tentatively suggests an inverse relationship
between Gyrodinium end Noetiluea abundanee in the Eastern
Irish Ses. In so Far as Noetiluea ean prey on diatoms, it
i5 possible that blooms oF Noctiluce are dependant on
inereased diatom populations; the Sherkin data shows that
gevcral diatem species were cemmon at this time. -14-
The role oF Freshwater inputs is not clearj 1977 was sn
exceptionally dry year compared to other years between 1975 and 1981 whan red tide events have occured. While the
Youghal area does receive the input oF the Blackwater river, other Iarge river estuaries were not noticeably associated with blooms, end many oF the inshore patches occurred in areas which do not receive large Freshwater inputs. There was no relationship betweenthe Few periods oF rain and the
incidence oF blooms. Thu5 the association oF Noctiluca blooms with convergence oF estuarine and coastal watars • observed by Le Fevre and Grall (op.cit.) does not appear to hold in this case.
There have baen suggestions that Noctiluca blooms are toxic though Morton and Twentyman ~1971) cast considerable doubt on this idea. No mortalities oF marine organisms or public health problems werF? ",ppol'ted during this bloom. Basking
Sharks (Cetorhinus maximus Gunnerusj were reported swimming through patches in the Youghal area. • AeFerences
BASSINDALE, ~., DAVENPORT, I.E., EBLING, F.J., KITCHING, J.A.,
SLEIGH, M.Ä. and SLOANE, J.F. (1957). The ec610gy oF
the Lough Ine rapids with special reFerence to water
currents. VI. EfFects of the rapids on the hydrography
oF the south basin.
Journal oF Ecology, 45.n7~-900 -15-
COOPER, L.H.N. (1967) The Physieal Oeeanography ~f th~
Celtie Sea. Harold Barnes, Ed. Allen and Unwin Ltd.,
London.
Oeeanography and Marine Biology Annual Reviews, 5, 99-110.
EVANS, O. (1977). Bloom algae in the eastern Irish Sea.
Seientific Aeport. The Laneashire and Western Sea-
Fisheries Joint-Committee, 1976. pp. 59-60.
REPOAT OF THE WOAKING GROUP ON RED TIOES ANO EUTROPHICATION • Aeport of the Working Group on Red Tides and E trophieation. ICES CM 1976/L:39
KAT, M. (1979). The oeeurrenee oF Prorocentrum speeies
and gastro-intestina1 il1ness of mussei eonsumers.
In Toxie Oinofiagellate Blooms [Taylor, Selinger Eds.).
Oevelopments in Marine Biology 1, 215-222.
LE FEVRE, T. and SRALL, T.A. (1970). On the relationships
of Noetiluea swarming off the west coast of Brittany
with hydrologieal features and plankton eharaehteristics • of the environment. Journal oF Experimental Marine Biology and Eeology 4,
287-306.
MORTON, B. and TWENTYMAN, P.R. (1971). The oeeurrenee and
toxieity of a Red Tide caused by Noetiluca scintillans
(MeCartney) Ehrenb., in the eoastal waters of Hong Kong.
Environmental Research, 4, 544-557 -16-
OTTWAY, 8. and PARKEg, M. (in preparation). A bloom of
Nitzschia sp. in the area oF Youghal on the south coast
oF Ireland, July 1978.
OTTWAY, G., PARKER, M., McG~ATH, D. and CROWLEY, M. (1979).
Observations on a bloom oF Gyrodinium aureolum Hulbert
on the south cOost oF Ireland, summer 1976, associated
with mortalities oF littoral and sub-littoral organisms.
Irish Fisheries Investigations 818. PARKER, M.M. (Editor), 1981. Red Tides: Proceedings oF a • seminar held at the Fisheries gesenrch Centre, Oublin,
March, 1979.
Fisheries Seminar Series No. 1, Department oF Fisheries
and Forestry, Dublin.
PINGREE, R.O., PUGH, P.R., HDLLIGAN, P.M. and FORSTER, G.R.
(1975). Summer phytoplankton blooms and red tides
along tidal Fronts in the approaches to the English
Channel. Nature, 258, 672-677. • PINGREE, R.D., HOLLIGAN, P.M., MA9DELL, G.T. and HEAO, R.N.
(1976). The inFluence oP physical stability in spring,.
summer end autumn phytoplankton bInoms in the Celtic Sea.
Journal oF the Marine Biological Association of the
United Kingdom L 56, 845 - 873.
PINGREE, R.D., HOLLIGAN, P.M. and HEAD, R.N. (1977) •
Survival oF dinoFLagellate blooms in the castern English
Channel.
Nature, 265, 266-269. -17-
RODEN, C.M., RYAN, T. and LENNON, H.~. (1980) . Observations
on the 1978 Red Tide in Aoaring Water Bay, Co. Cork.
Journal of Sherkin Island, 1, 105-118.
ST~ICKLAND, J.D.H. and PARSONS, T.R. (1968). A Practical
Handbook of ~eawater Analysis.
Bulletin of the Fisheries Research 80ard of Canada, No.167. • 52 ...I CD I
.-' '\ Ga'Rigo 6b
Figure 1: The south coast oF Ireland, indlcatlng location oF Sherkin Island, Lough Hyne, sites oF incidence oF discoloured water (numbers are explalned in the text) and Meteorological Stations. ;:: 1 gure 2 ~ Meteere 1egica 1 data 4Ieches Pt., :erk: and' ~ I da i dae . CebM, Co-k} f er- the south coast, summer 1977, and dates of, incidence oF coastal olooms.
20 WindlPHd kt$/hr aQyr.ovg.
0
20 Rainfall mm .avg. 0
10 ....I tO aDyr.ovg, I·
20 MAX.
1------=:------~-----_F;;r_-----__r_~F__+_------TOOyr.avg. MIN. 10 TempE'rotur~.
4.5ITi~ h~ght ••• • m • ••• • ••• • • • ••• ••• ••• ..-...... e.. •• • e • ••• • ••• ••• •• ••••• • •• • •••• I • •••• • ••• • •••••• 3 Blooml o o
i i , i , I i i i i i I ii , i i i i i i » i i i i i i I • i i i i • i , I i i i i i i i i i f 141516 15 2~ JULY AUGUST 8910 ...,
20 mm o ReinFall
10 hl"i/'d I oy N C 0 ...... ------..J....J. -...;.__--!..--1 _ I
~~+~Noctilucon r-l-J 1 nOi/m2 102 1--- U - L n [l 1g ____"__---~-~-~l__LfLcfl'---"LD_
, i $ see , i U , i ' , s' i7 ' 1~ $ 21J• 28 1~
Figure 3: Meteorological data recorded at Lough Hyne and dens~ty of Noctiluca recorded at Station C. Figure 4: Lough Hyne; Isotherms (oe as -16-) and secchi depth (as ••• ) for summer 1977.
I ru ~ • •• •• • I • •• • • • • • • • • - • • • 16
15 20 J •
-22-
10km
• Fa~tn~t
Figure 58: South West Cork, showing loc~tion oF Lough Hyne and Sherkin Is18nd 8nd other places mentioned in the text.
1km 2,I Figure Sc: Sherkin Island and surrounding area to show sampling points at Jones Figure 5b: Lough Hyne, to show Island (1), The Dock (2), the Ioeation of Station C. Kinnish Harbour (3) and Truhane Point (4). 1 2 Reinfall mm 0-4.-&:~--'=:=...I. ~=---I.._....J~_~::J...J....-== ...J.._..c~_ I N (,J I o Noctiluca 10 c~1I1 ><103 .•6;.. ~""__...I.IIiU--__-I-.a...-_...,II;~__L-J..__.J.IMi.LI -I-.1-_J:·~ __...L..L'O '7 b. Figure E: ,~eorological data recorded at Sherkin Island, with sea temperature, chlorophyl CDMCentration and Noctiluca density (stippled bars) recorded at Kinnish Harbour • ..