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466 South African Journal of Science 102, Se

Observations of the habitats

of the submarine canyons at

K.J. Sinka*, W. Boshoff

b

, T. Samaaic

, P.G. Timm and S.E. Kerwa

expandthe use

extendIn Sosubtida

The discovery of coelacanths, Latimeria chalumnae, in Jesser

Canyon off Sodwana Bay in northern KwaZulu-Natal in 2000

triggered renewed interest in the deep subtidalhabitats associated

i h b i I f i i f h

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Novemthe dis

documapprox

Inverte

InverexpedipapersAfter iSouth APieterm

inverte

Analys

Coelacanth Research South African Journal of Science 102, Se

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either Jesser or Wright Canyon. Strong currents were confinedto the top 30 m and no currents were noticed below 50 m. In

Wright Canyon, sea-surface temperatures ranged between 22and 24C. Thermoclines were evident between 14 and 21 mduring all dives, with bottom temperatures ranging between 16and 20C (Table 1). Surface temperatures were not docu-mentedin JesserCanyonbut, towards thebottom,temperaturesdeclined to 1719C during all dives.

TopographyA general description of thetopographyof Wright Canyonwas

compiled from diver observations. Between 75 m and 90 m a

gently sloping sandy area with scattered rocky outcrops wasfound. Features that were discovered included four large rockydomes (approximately 8 m tall and 15 m2 in size) (Table 1 dive 1)

early 1were p

(Pachacaliculafrom tlissoclaIsodictHyppos50 m oClathro10 otheAfrica.

Hydroc

Ther


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Table 2. List of invertebrate taxa collected in Wright and Jesser canyons.

Group Family Species Wright Cany

depth (m)

Porifera Pachastrellidae Poecillastra compressa 90

Pachastrellidae Pachastrella monilifera 75

Pachastrellidae Pachastrellacf. monilifera 75

Pachastrellidae Pachastrellasp. 75120

Calthropellidae Clathropellasp. 85

Hemistrellidae Hemistrella vasiformisvar. minor 100140

Hemistrellidae Hemistrellasp. 75

Halichondriidae Hymeniacidon caliculatum 120

Halichondriidae Halichondriasp. 100140

Halichondriidae Topsentia pachystrelloides 90Axinellidae Axinellasp. 1 90

Axinellidae Axinellasp. 2 85

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species3 and

observmenteleast 18and fuone-strfish suother cthe canPolysteDivers

footagewrasseamblyce


Table3. Theten most common macroinvertebrate taxa at depthsof 100110 m atJesser Canyon margin as determined from SIMPER analysis of abundance datafromfive videotransects.The ranking is determinedby Si, the averagecontribution

of each species to the overall similarity of the area.

Family Species Mean* Si/s.d.(Si)

SI%

1 Antipathidae Stichopathes sp. 1 7.8 2.71 29.4

2 Antipathidae Stichopathes sp. 2 1.8 1.09 39.83 Ellisellidae Nicella dichotoma 5.6 0.62 48.84 Stylasteridae Stylastersp.1 1.2 1.14 55.75 Asteroschematidae Asteroschema capensis 2.6 0.62 61.6

6 Phellodermidae Echinostylis sp. 4.4 0.60 66.77 Ellisellidae Junceella sp. 2 3.8 0.62 71.68 Diademnidae Diademnum sp. 1 0.6 0.61 75.4

9 Phidoliporidae Unidentified sp. 0.6 0.61 79.010 Stylasteridae Stylastersp. 2 0.6 0.61 82.3

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Hieraccommu

positiothe twblack cratio Sdichotois thesedance sp.2

Caves

WithdistincDistich


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reflecting that research in deeper watershaspotentialto expandour knowledge of the distribution and ecology of benthic

subtidal species. In addition, several conspicuous but unidenti-fied invertebrate species were evident in video footage.The identification of material was difficult in terms of local

availability of expertise, keys and literature. Sponges, molluscsand bryozoans were identified by local taxonomists andechinoderms were identified by experts from London. For 24families, no assistance could be found in South Africa. Thisincludes families belonging to groups such as soft corals and

black corals, important taxa that constitute fish habitats in thecanyon and other deep-water environments. This lack of

taxonomic expertise in South Africa threatens our understand-ingof marine biodiversity.5 Thiscountry clearlyneeds to cultivateexpertise in invertebrate taxonomy and extend collecting efforts

Fish con insh

one-strwidespthe GShas beare few

Aulacocshallowfrom awere foreefs8 i

ChrysoPolysteDepth


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this habitat. Patterns in fish abundance also support this idea.The most abundant fish along the canyon margins were

planktivorous: fusiliers, lutjanids and the small serranidPseudanthias fasciatus. In the Caribbean, fish communities fromreefsatdepthsof80150marealsodominatedbysmallserranidsandotherplanktivores that then supportlargepredatoryfish in-cluding serranids.3,31 The planktivorous species of the canyonmargins in the GSLWP may constitute important prey items forserranids and other large piscivores including coelacanths.3,32

There issome similarity in thedeepsubtidal fish communityinthe coelacanth habitat on the slopes of Grande Comore and inthe canyons of Sodwana Bay. The fish families most frequently

observed by the Jago in the 80200 m zone of the coelacanthhabitat of Grande Comore were also documented by Trimixdivers in the Sodwana coelacanth habitat 33,34 Additional fish

assistanc

Western

Pieterma

crustacea

determin

grateful

in exami

acknowl

This rese

Technolo

tered thr

Facility o

Environm

the FRS A

1. Lehn

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21. Colin P. and Arneson C. (1995). Tropical Pacific Invertebrates. Coral Reef Press,Beverley Hills, CA.

22. Hayward P.J. and Ryland J.S. (1999). Cheilostomatous Bryozoa Part 1. Hippo-

thooideaCelleporoidea. Field Studies Council, Shrewsbury.23. Gosliner T.M., Behrens D.W. and Williams G.C. (1996). Coral Reef Animals of the

Indo-Pacific: Animal Life from Africa to Hawaii Exclusive of the Vertebrates. SeaChallengers, Monterey, CA.

24. Debelius H. (2001). Nudibranchs and Seasnails Indo-Pacific Field Guide. IKANUnterwasserarchiv, Frankfurt.

25. King D. and Fraser V. (2002). In More Reef Fishes and Nudibranchs, pp. 112128.Struik, Cape Town.

26. ClarkeK.R. andWarrickR.M. (1994).Changein MarineCommunities: an Approachto Statistical Analysis and Interpretation. Plymouth Marine Laboratory,Plymouth.

27. Clarke K.R. (1993). Non-parametric multivariate analyses of changes in

community structure. Aust. J. Ecol. 18, 117143.28. Clark A.M. and Courtman-Stock J. (1976). The Echinoderms of Southern Africa.

Trus

29. Smitnesb

30. Riegsout

31. WeavfoodUnitStreapp. 1

32. Uyenfurth

33. Frickof th

34. FrickLatim149

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