The replacement of natural hard substrata : its effects on sponges and ascidians

1 Pages·1999·0.1 MB·

by  N Knott

MEMOIRS OF THE ObCFNSLANDMUSEUM
: ries Sciences Nfiiurslles de Belgtqi : WRIGHT, \.D.. KONI kNGERHOFEJt,
: iM,, ! :, PT, RICCWl, C. & IIART- DC.EKS..QUGERYEIROU[XI -FA.LPJ.,NDLETZND,1 R. 199(5
i\NNk I i i ti i Antimalarial activity: The search for marine
pyrroli/idine alkaloids from natural sources b> derived natural products which demonstrate
chromatography -ma- | ClrOIT) otivi Journal ofNatural
. Products59; 7IU-7I6.
THE REPLACEMENT OF NATURAL HARD ascidf.fi rrtical than on horizontal surfaces. It has
SUBSTRATA BY ARTIFICIAL SUBSTRATA: ' whether these pattern^ exist in the
S EFFECTS ON SPONGES AND ASCIDIANS tempi
I l .'',.
a f\ii r/w W: 2-8&.,i . Studiesthathave examined rhe effectsol al and
i ; ,,, vortic.i ' (he distribution ofsponges and
Coim,mm,,onl,y; . thiese LaerceyQnfantuartaulrarloaenkdarneieflicfalsubstrata. thai cause the-se d.biasgtr,ielxup.tejir.imi e,ntal^ rested the factors
scawalkaitd pi pesofhard Hen | | :
differ in their structure. Most natural hard ib i that sponges and aseidvans are more ahundai1
consist bcu ntal surfaces; mosi ces on vertical thanhorizontalsurfaces in the sha h nbthtal
artificial hard substrata are vt [a ;ncrcforc. 50ne around '• i .,
. ; . ii. .. i !; Rcjj ' I] 11.11i\e experiments to determine which !fl!
is likely to ibstraia are.i.mp.or.ta.nt.in creating these distributions
Itom predoi i lOrizonlal ta mostly vertic iJ , .
understand and pre*
changes on the assembI lag cans it
rerrnine their distribution on Nathan
fooriz i d vertiical surfaces,.. h Centreon I
l_. . ti iviiesituodni horizontali an.idil vertnica"li i IJuneJm.
-.polled thai there are esand
i
CCOONNTVIENRUGUEMN:CE AIN TPHREEDTAITMOER-SPPRAECEY K.nv inddaktaatiwoerecoiimajor monalfrrjimeev.ents. No pc i dj I
IMNusreiulmtA44C:TI28O8N, 1999:- Community 1 .I al iambers r>f tl I I i ' i Iiihredatocrhiod
influenced b\ man; bioiic and a1 ctors, . .
atioj cturing rnechanisin fbi some 1996, In the spring ol
withosetrceonmgtmhunoiftiperesd.atPorreyreacbruuintdmaennctesandmapyersfilsutcetnucaet,e 15! A.i rmeucnrtueirtemyeenntsir.esulted inFarnomavMearaygetoJim peiiioneonf
'vheresomeoftheprey population hasa ooverol (i fhtrrnca declined ualestimatesol
i _.e in space or Time from predation. Consistent. 40% in May to 15% in July. L-: I 1^97, whenthe
predation levels on a predicabl) available 10 permanent quadrats and IG haphazard]}
reIsource should lead le community quadratsweremeasured,essentially nospongeco|uIldbe
structure with relatively small fluctuations in predator found at the study site. After July, ihe abundan U
andpreypopulationdensities.Conversely,rjre> species nudihranchs declined to 32 individuals commensurate
i' ge from predation are subject In major sponge reduction. By September, only one small
population fluctuationscommensurate -1 igthof \y and 7 predate ircfts were
Ltor reeniiTmeni and abundance. nt atrhe sue. IIven though // panlcen is abundant
rhe sponge Haiteftondrlci i is patently in theregionand potential recruitsshouldbenumerous,
dlKioascctarhticibmuotaneskd iiBnsatyht,eher5o0Usc1pkaytiCiiCannltfierdnominant. At oneorseiotef aisnnp;uriaeldoi-mimi1a1Dic19r9io8!,.tohepsiioteccounrcreindgo.minTahteedpbrvedHa.tpoarn-ipcfeeya
n 11- //.panieeahas relationship of I n eastsandI ris an
dominated themid-intertidal lor at least 10 years, v iih example of li chase through space and time with
low densities ofpotential molluscan predak,. sucha convergence resulting L] E :treme population
crisis, Kiithcrim umicata^ and rid an unstable canunurd 3 Forifsro.
primarysp.a,ce occu| peiseernst.atPtehercent cover estimatdefsroomY interaction cnoumdmjubnriatnychs,truicntnurer Alaska, recmiitm. >m
1109904..25tim.'ppaenrimcaenaenatveqruaagdrats established1.i9n%\cover A'm'I.'Knawlton (email ]}Luk<n:i:;;;.,:<h:> & Raymond C.
i 1996. I lories i kh ofFfsfia
wLe."r-eio i i'rs! to, th.e-6.s4i^t,e. and roipensprrioncgk,of261.9197% aBtnxtxfO"ceaf}S ewbank trUw/^/!fj ' \tasl fyiri .. '• PC).
wealed that lb colonies overwintered with
.