ANNA.IES • Ser. hist. nat. ■ 12 • 2002 • 1
original scientific: paper	UDC 591.5:597(262.3)
received: 18. 9. 2002
A VISUAL CENSUS OF THE COASTAL FISH ASSEMBLAGE AT KOSTRENA
(THE KVARNER AREA, CROATIA)
Matcelo KOVAClC
Ptitodoslovni muzej Rijeka, HR-51000 Rijeka, lotenzov prolaz 1 E-mail: Marcelo.Kovacic@public.SEce.he
ABSTRACT
The modified stationary visual census technique (point method or circular point method) was used to provide a preliminary description of fish assemblages at the locality of Kostrena (the Kvarner area, Croatia). A high number (52) offish species was recorded. The results also showed strong influence of substrate composition and bottom depth on the fish community, at least on fish species composition. Samples grouped in cluster analysis in five habitat types based on similarity of bottom and depth characteristics. The community parameters between groups were significantly different.
Key words: fish assemblages, Adriatic Sea, visual census
VISUAL CENSUS DELLA COMUNITA ITTICA LITORALE Dt KOSTRENA (AREA
QUARNERINA, CROAZIA)
SINTC.5I
L'articolo riporta una descrízione prelíminare delle comunita íttíche di Kostrena (area Quamerina, Croazia), ot-tenuta con la técnica del visual census, con I'utilizzo di un sistema fisso di osservazione. L'autore ha regístralo un numero elevato di specie itliche (52). I risultati indicano una forte influenza della composizione del substrato e delta pro fond tú deti'acqua sulla comunita ittica, almeno per quanto riguarda la natura delle specie. I camp ion i sono stati raggruppati in cinque tip/ di habitat in base alie somiglianze delle carafíerístiche di substrato e profondita, con I'uso delta cluster analysis. I parametri di comunita differiscono significativamente tra i vari gruppi.
Parole chiave: comunita ittiche, mare Adriático, visual census
1
ANNA.IES • Ser. hist. nat. ■ 12 • 2002 • 1
Marcelo KOVAČiČ: A VISUAt CCNJUS OF THECOASTAl FISH ASSFM8I ACf ATKOSTRENA (THf KVARNtR ARM. CROATIA/. 1-3
INTRODUCTION
The marine area of the Kostrena municipality has been proposed for protection as a submarine park by the Primorsko-Goranska County. In order to prepare a proposal for the protection program, a thorough investigation of the geology and biology of sublittorai sea bottom of the Kostrena municipality was conducted. The Kostrena is recreational area with well preserved beaches and coastal zone, but situated in the northern part of the Rijeka Bay, which is heavily polluted by domestic and industrial waste (Fig. 1). According to jardas etal. (1998), there are no published data on coastal fish assemblage at Kostrena.
The main aim of the ichthyological investigation was lo provide a preliminary description of fish assemblages at the locality of Kostrena; consequently, the visual census method was chosen as the one best suited to this aim.
MATERIAL AND METHODS
The geomorphological, sedimentological, bioce-nologicai and ichthyological researches were carried out at four locations (KOI, K02, K03, KG41 (Fig. 1) in the summer of 199*3, from July to August. Modified stationary visual census technique (Bohnsack & Bannerot, 1986, also named point method by Bortone et a/., 1989 or circular point method by F rancour, 1997) was applied. The point method advantages were listed in Bohnsack & Bannerot (1986). However, the main reasons for point method in this research were steep bottom, habitat changes along with depth and habitat patchiness (heterogeneity). At the four locations (KOI, K02, K03, K04) (Fig. 1), visual fish censuses were performed at the depths of 0, 2.5, 5, 7.5, 10, 15, 20, 25, 30, 35 and 40 m during morning hours. Bottom characteristics at different depth points were recorded., and bottom type classified as soft bottom (sand, muddy sand with <1/6 of surface consisting of cobbles, boulders and bedrock), mixed bottom and rocky bottom (cobbles, boulders and bedrock with <1/6 of surface covered with sand). The phytal cover was not taken into consideration. However, the algal cover at all four locations was poorly developed and erected macroalgae or seagrass were not present. The largest depths were not reached at KOI (40 m) and KC)4 positions (30 m. 35 m, 40 m). Altogether, a total of 40 point counts were carried out (KOI: 10, K02: 11, K03: 11, K04: 8). Diver rotated at a point making a full circle (360,}) during 5 minutes and counted the fishes occurring in his visual field within a defined area. Hyperbenthic and benthopelagic fishes were counted within a circular area of 4 rn radius (50 m2), and epibenthic fishes within a circular area of 1.8 m radius (10 m2). Counting areas smaller than usual (Bohnsack & Bannerot, 1986, Boitone er a/., 1989;
Francour, 1996) were chosen because of the high relief, which covered the visual field, especially for small ephibenthic species. A marked line was used to estimate the radius. All chosen depths were taken as a centre of the counting area, except at 0 m where this point was in fact the edge of the counting area. Fishes were counted according to the abundance scale based on a basic geometric progression factor of 2 (!, 2-5, 6-10, 11-30, 31-50, 51-100, >100). According to Bohnsack & Bannerot (1986), the density of fishes, expressed as the number of individuals per 10 rn1, was considered an index and not an absolute datum.
Fig. 1: Sampling area: a) the Adriatic Sea, b) the Kvarner area, c) the Kostrena coast with investigated K01-K04 locations.
SI. 1: Vzorčišče: a) Jadransko morje, b) Kvarner, c) kostrensko obrežje z raziskanimi lokacijami K0I-K04.
Qualitative affinities between samples were studied by means of the Jaccard similarity index (Krebs, 1989), using the centroid method for hierarchial classification analysis. Abundance data were compiled for each group of samples from cluster analysis, and the following community parameters were calculated: mean species number, mean individuals number and species diversity (the Shannon-Wiener diversity index H' according to Krebs, 1989). The significance of the differences of community parameters among groups was tested statistically using the non-parametric Kruskal-Wallis test.
2
ANNALES • Ser. Iiist. nat. ■ 12 • 2002 • 1
KOVAČfČ; A VISUAL CiNSUS OF THf COAJTAl FISH ASSEMBLAGE AT KOSI KCNA (THf KVARNFfi AKfA. CROATIA?, 1-f!
Tab. i; List of recorded fish species with quantitative data: a)-f), pooled samples based on cluster analysis, bottom and depth characteristics explained in text; meants.d., mean abundance with standard deviation; F%, frequency of occurrence. Underlined species are those observed out of the counting points during SCUBA divings. Tab. 1: Seznam zabeleženih ribjih vrst s kvanitativnimi podatki: a)-0, podatki, zbrani na osnovi grozdičaste analize, pridnene in globinske značilnosti pojasnjene v besedilu; sred.±s.d., srednja gostota s standardno deviacijo; F%, frekvenca pojavljanja. Podrčrtaiie vrste so zunaj števnih točk opazili potapljači.
	a) & b)		c)		d)		01		f)	
Species	ineaiiis.d.	F%	inean+s.d.	F%	mean+s.d.	l-%	mean+s.d	F%	mean+s.d	F%
Aidablennius sphynx (Valenciennes, 1836)	0.1 3+0.35	12.5	0	0	0	0	0	0	0	0
Alherína sp.	2.5+7.07	12.5	2.22+6.67	11.1	0	0	0	Ú	0	0
Boopí boops {Linnaeus, 1753}	0	a	3.28+6.79	33.3	5.45+7.85	45.5	5+9.26	25	0	0
Buenia aftinls lljin, 1930	0	0	0	0	0	0	0.25+0.46	25	0	0
Chromis chrornis (Linnaeus, 1758)	0.4*0.7	25	2.02+2.55	77-8	2.25+3.24	45.5	0	0	0	0
Caris ¡ulis(Linnaeus, ! 7Sñ)	1,16±1.3	75	1.28+1.16	88.9	0.47+0.61	63.6	0.13+0.1	62.5	0	0
0iplodus annularis (Linnaeus, 1 758)	0	0	0-09+0.11	44.4	0	0	0	0	0	0
Diphdus punta zz o (Cetti, 1777)	0	0	0.02+007	i t.l	0	0	0	0	0	0
Diplodus sarga; sargus (Linnaeus, 1758}	o.oa±o.io	37.5	0.02*0.07	U.I	0	0	0	0	0	0
Diplodus vulgaris (E. Gooffroy Sainl-Hilaiie, 18)7)	0.03±0.07	12.5	0.12*0.23	33.3	0	0	0	0	0	0
Gobius bucchichi (Steindachner, t870]	!.38±1.38	75	0.22+0.44	22.2	0	0	0.1 3+0.35	12.5	0	0
Gobius cobitis Paltas, 181!	0.25*0.46	25	0	0	0	0	0	0	0	0
Gobius cruentatiis Cmelin, 1789	0	0	0.33+0.5	33.3	0	0	0	0	0	0
Gobius geniporus Valenciennes, 1837	0	0	0 11+0.33	11.1	0.09+0.31	9.1	0.13+0.35	12.5	0	0
Gobius route! De Buen, 1928	0	0	0	0	0.18+0.4!	13.2	2+1.65	75	1.63+1.25	1Ü0
Gobius viliatus Vinciguerra, 1883	0	0	1.56+0.37	100	1.81 + 1.37	90.1	0	0	0	0
Gobius xanthocephalus Zandet & Heymer, 1992	0	0	0.33+0.5	33.3	0.18+0.4!	13.2	0	0	0	0
Labrus biinaculatus Linnaeus, 1758	0	0	0	0	0.Ü9+0.30	9.1	0	0	0	0
iipophrvs canevá/(Vinciquerta, 1880)	0.25+0.46	25	0	0	0	0	0	0	0	0
Oblada melanura [Linnaeus, 1758)	3 51+6.79	75	1,1 + 1.29	77.8	0.06+0.21	9.1	0	0	0	0
Parablermius gattorugine (Bnmnich, 1788)	0	0	0	0	0.09+0.3	9.1	0	0	0	0
Parablermius incognitas (Bath, 1968}	0.38+0.52	37.5	0.11+0.33	11.1	0	0	0	0	0	0
Parablermius rouxi (Corc.o, 1833)	0.25+0.46	25	1.56+1.1	100	1.27±1. i 7	81.8	0.1 3+0.35	12.5	0	0
Parablermius sanguinolentos (Pallas, 1811)	0.38+0.S2	37.5	0.11 ±0.33	11.1	0	0	0	0	0	0
Parablermius tentacularis (Bnmnich, 1788)	0	0	0	0	0	0	0.13+0.35	12.5	0	0
Parablennius zvonimiri (Koiombatovic, 1892)	0.63±0.52	62.5	0	0	0.09+0.31	9.1	0	0	0	0
Sarpa sal pa (1 innaeus, 1758)	0.18+0.32	25	0.8+1.39	33.3	0.06+0.2!	9.1	0	0	0	0
Scorpaena porcus Linnaeus, 1 758	0	0	0	0	0. Ifl±0.4I	18.2	0	0	0	0
Serranus hépatus (Linnaeus, 1758)	0	0	0.09+0.11	44.4	0.15±0-09	72.7	0.13+0.1	62.5	0	0
Serranus scriba (Linnaeus, 1753)	0.05±0.09	25	0.04±0.09	22.2	0	0	0	0	0	0
Speíeogobíus írigíoides Zander & Jelinek, 1976	0	0	0	cT	0.59+1.07	36.4	0	0	0	0
Spicara maena (Linnaeus, 1758)	0	0	0	0	0.36+1.21	9.1	0	0	0	0
Spicara smarts (Linnaeus, 1758)	0	0	1.88+3.48	44.4	0.35+0.65	27.3	0	0	0	0
Spondyliosoma catilharus (Linnaeus, 1758)	0	0	0.02±0.07	11.1	0	0	0	0	0	0
Symphodus (Crenihbnts) cinereus (Bonaterre,										
1788)	0	0	0	0	0	0	0.03±0.07	12.S	0	0
Symphodus ("Creni/abrusJ mediterráneos (Lin-										
naeus, 1 758)	0	0	0	0	0.04+0.08	18.2	0	0	0	0
Symphodus (Crenilabrus) ocellatus (fotskal, 1775)	0.031-0.0?	12.5	0.09+0.11	44.4	0	0	0	0	0	0
Symphodus (Creniiabrus) linca (Linnaeus, 1753)	0.03+0.07	12.5	0.16+0.09	77.8	0	0	0	0	0	0
Thorogobius ephippiauts (Lowe, S 839)	0	0	0	0	0.36+0.5	36.4	0	0	0	0
Thorogobius maaolepis (Koiombatovic, 1891)	0	0	0.11+0.33	11.1	0.96+0.96	72.7	0.13+0.35	12.5	0	0
Trlpterygian delaisi Cadenat & Biache, 1971	0	0	0.22±0.44	22.2	0.36+0.5	36.4	0	0	0	0
Tripterygion tripteranotus (Risso, 1810!	0.38+0,52	37.5	0	0	0	0	0	0	0	0
										
17S8 "										
Leparfogaster candolcit R jsso. 18)0										
Lcnariofjaster fepadogasfer fepadogastertBon-										
n aterre. 1783']										
Lipophrvf, dalnutinus (Stqindachnet & Koiomba-										
lovir. 1883)										
ii¡x>phrvs nigriceps (Vi nci^fuerra, 1883)										
Scarpaenp nofara'l^afinesqlie. 1810										
Tripterygiffft mehnurus minor Koiombatovic.										
Zebras ¿ebru^RvfS.0 1810)										
Number of point counts	8		9		11		8		4	
Mean number of species	6.5+2.6		9.88±2.22		7.45+1.86		3.25+1.67		1	
Mean number of individuals	11.95+10.02		19.04+8.61		! 5.47+10.55		8.15+8.67		1.63+1.25	
Species diversity	1.91 ±0.4		2.33±0.70		2.3+0.51		1.22±0.71		t i	
Total number of species	59		26		22		11		1	
3
ANNALES • Ser. Iiist. nat. ■ 12 • 2002 • 1
Marcelo KOVAČI C: A ViSUAS. CENSUS Of THE COASTAL fl5h( ASSUME?IAG£ Al KOSTRENA (THE KVARNER AREA, CROATIA), 1 -fi
Mann-Whitney U-test was used for multiple comparisons (Sokal & Rohif, 1995). Cluster analysis and tests of significance were carried out by the SPSS 9.0 program. The Shannon-Wiener diversity index was calculated by the use of Ecological methodology 5.2 program (C. j. Krebs, 2000: Programs for Ecological Methodology, 2na edj.
RESULTS
A total of 52 fish species were recorded, 42 were censused during point counts, while others were randomly observed during ihe same SCUBA divings {Tab. 1). The dominant families in terms of species number
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Fig. 2: Cluster analysis between visual census samples. Similarity index of Jaccard and centroid method for hierarchical classification analysis. R: rocky bottom, M: mixed bottom, S: sandy bottom; 0-40: depth (m); KOf-K04: locations.
SI. 2: Crozdičasta analiza med vzorci vizualnega štetja. Jaccardov indeks podobnosti in centroidna metoda za analizo hierarhične razvrstitve. R: kamnito dno, M: mešano dno, S: peščeno dno; 0-40: globina (m); KOI-K04: lokalitete.
Mean species number / Srednje it. vrst	ab	C	d
e	*	*	*
d			
c	*		
			
Mean individuals number / Srednje št. osebkov	ab	C	d
e	*	*	*
d			
c			
			
Species diversity / Diverziteta vrst	ab	C	d
e		*	*
d			
			
c			
Fig. 3: Results of Mann-Whitney U-test for multiple comparisons of mean fish species number, mean individuals number and species diversity between pooled samples based on cluster analysis (a-e). The bottom and depth characteristics explained in text.
*	- denotes significant difference (P<0.05) between two groups of samples.
Si. 3: Rezultati Mann-Whitneyevega U-lesta za večkratne primerja ve srednjega števila ribjih vrst, srednjega števila osebkov in diverziteto vrst med vzorci, zbrani na osnovi grozdičaste analize (a-e). Pridne ne in globinske značilnosti so pojasnjene v besedilu.
*	- ponazarja pomembno razliko (P<0.05) med dvema skupinama vzorcev.
were Cobiidae (14 species) and Blennudae (10 species). Hierarchical classification analysis among the Kostrena samples showed grouping of samples based on similar bottom arid depth characteristics (Fig. 2). Six main clusters belonged to five habitat types with the following depth and substrata characteristics: a) and b) rocky bottom 0-2.5 m depth, c) rocky and mixed bottom at 5-10 m depth (except for the counting point R15K03), d) rocky and mixed bottom at 15-30 m depth (except for the counting point R10K03), e) sandy bottom at 5-20 m depth and mixed bottom at 30-35 m depth, and f] sandy bottom at 25-40 m depth (Fig. 2). Poorly inhabited sandy bottom at 25-40 m depth clearly differed in quantitative characteristics of fish assemblages from all other habitats (Tab. 1). The community parameters between the four remaining groups were significantly different (Kruskat-Waliis = 20.52 in species richness, 11-43 in abundance and 9.1 in species diversity, alt P<0.05). Habitats differ significantly in species richness except for
4
ANNALES • Ser. hist. nat. • 12 • 2002 • 1
M,lic do KOVaCiC: a Visual cfnsus Of THE coa5tai FISH assemblage AT kostrina (THE KVARNER AREA, croatia», 1-8
habitats ab) and d) (Mann-Whitney LMest, Fig. 3). Fish density was significantly lower only in habitat e) compared to all other tested habitats. The habitat e) also showed significant differences from habitats c) and d) in species diversity (Mann-Whitney U-test, Fig. 3). The most common and abundant ephibenthic fish species during the visual census at Kostrena were: Gobius buc-chichi in shallow waler, Gobius vittatus and Parablen-nius rouxi on the rocky bottom of >5 m depth, with Tho~ rogobius macrolepis of >15 m depth as well (Tab. 1), and Gobius roulei on the sandy bottom. Among hyper-benthic and benthopelagic species, Atherina sp., Cons julis and Obi ad3 melanura were the most common and most abundant fishes in shallow infralitloral, while Boops hoops and Chromis chromis were the most common and most abundant fishes in deeper infralittoral. The high density of these two groups overlapped between 5-10 m depth (Tab. 1).
Fig. 4: Available data on visual census of fish assemblages in the Adriatic Sea: 1 - Marconato et a!., 1996; 2 - Fasola et a/., 1997; 3 - De Girolamo et a!1998; 4 -Guidetti, 2000; 5 - Guidetti & Bussotti, 2000; 6 - Cas-teflarin et a/., 2001; 7 - Lipej & Orlando Bonaca, in prep.; 8 - the present research.
SI. 4: Razpoložljivi podatki o vizualnem štetju ribjih združb v jadranskem morju: 1 - Marconato e( ai, 1996; 2 - Fasola et ai, 1997; 3 - De Girolamo et ai., 1998; 4 -Guidetti, 2000; 5 - Guidetti & Bussotti, 2000; 6 - Cas-tellarin el al., 2001; 7 - Upej & Orlando Bonaca, in prep.; 8 - pričujoče raziskave.
DISCUSSfON
The present visual count of fishes is one of only a few performed visual counts of fish assemblages in the Adriatic Sea (Marconato etal., 1996; Fasola era/., 1997; De Girolamo et ai, 1998; Guidetti, 2000; Guidetti & Bussotti, 2000; Casteilarin et a!., 2001; Lipej & Orlando Bonaca, in preparation)(Ftg. 4). The present preliminary observation on the fish community was conducted on too small sample to provide an estimate of the absolute abundance of fish species at the Kostrena locality. However, it is a good qualitative description of fish assemblages and clearly shows the most numerous fish species in the habitats during the summer when the visual counts were carried out. It is difficult to compare the most numerous fish species with other published visual census resulls in the same zoogeographic area (the northern Adriatic). Marconato el ai. (1996) and Oe Girolamo et a/. (1998) did not give any details on fish species abundance. Casteilarin et a!. (2001) performed visual counts only in shallow water (<5 m depth). The most numerous fishes in their results during summer months were hyperbenthic and benthopelagic Atherina spp. and O. melanura, but also several other species not recorded, or at least not common at Kostrena (Mugil cephalus, Spams aurata, Sciaena umbra, Sarpa salpa). Coris julis, abundant in shallow waters at Kostrena, were not mentioned in their list. Gobius c.ruentatus were similarly abundant as C. bucchichi among epibenthic species. The present data with 40 point counts show a surprisingly high number of fish species, compared to other published results of visual counts in the Mediterranean, often conducted on much larger samples, and combined with other sampling techniques (Francour et a!.r 1995, 332 counts and 38 fish species; Harmelin-Viviert et ai., 1996 with 1081 visual counts and 48 fish species; Vacchi et ai., 1998 with 129 visual counts and 48 fish species). Only a few researches recorded larger species richness by SCUBA diving (Harmelin et ai, 1995; Mazzoldi & De Girolamo, 1997; La Mesa & Vacchi, 1999; Lipej & Orlando Bonaca, in preparation). The noted species richness during the present research was caused by a high number of found Blenniid and Gobiid species, reached in the visual counts of Mediterranean fish assemblages only by Mazzoldi & De Girolamo (1997), Casteilarin et ai. (2001) and Lipej & Orlando Bonaca (in preparation), it is more likely that the small epibenthic fishes, especially gobies, are underestimated in the Mediterranean visual censuses in general, than that the fish assemblages at Kostrena are especially rich in gobiid fauna. Several species of presently found go-biids are still known only from a few published records: Buenia atfinis, G. roulei, Speleogobius trigloides, T. macrohpis (Kovacic, 1995, 1997, 2002; Ahnelt & Ko-vacic, 1997). Speteogobius trigloides was discovered and described from cave habitat (Zander & Jelinek,
ANNALES • Ser. Iiist. nat. ■ 12 • 2002 • 1
Marcelo KOVAClC: A VISUAL CfNSUS OF THE COASTA1. FISH AS5EMBI AC6 AT KOSTREN* (THf KVARNER AREA. CROATIA!, t-8
1976). However, later findings were at open bottom surfaces (Kovacid, 1997; fesser, 1980; this work). The papers publishing comparisons of visual census data from different infraiittoral habitats or depths in the Mediterranean are rare. Guirietti (2000) compared fish assemblages at rocky bottoms, Posidonia meadows and bare sands. He came to similar results as the present study of higher species richness and fish density on rocky reef habitats than on bare sandy bottoms. Other papers compared visual census data between different seagrass meadows (Bussotti & Guidetti, 1999), bottoms with presence or absence of Caulerpa (("rancour el a!., 1995; HarmelirvVivien el al., 1996), or rocky bottoms with or without erect macroalgal cover (Guidetti & Bussotti, 2000). Several papers with visual census data from two or three defined depths in the Mediterranean have been published (Francour, 1994; francour et al., 1995; Mazzoldi & De Girolamo, 1997; Vacchi et al., 1998; La Mesa & Vacchi, 1999). However, due to the purpose of these papers, little attention was paid to comparisons of species composition and the community parameters among different ciepths. La Mesa & Vacchi (1999) observed that community parameters increased significantly with depth from shallow (3-5 m), intermediate (10-15) m to the deep transect (25-30 m), while the present research points out a significantly higher richness of species at medium infraiittoral depths.
Fig. 5: Cobius roulei. (Photo/Foto: M. Kovacic)
Fig. 6: Thorogobius macrolepis. (Photo/Foto: M- Ko-vacic/
CONCLUSIONS
The results of the preliminary observation of the fish community, especially the high number of fish species, justify the proposal to establish a protected area at the Kostrena locality. The results also showed strong influence of substrate composition and bottom depth on the fish community, at least on fish species composition. The absence of large species of rocky habitat {Labrus spp., Sciaena umbra, Scorpaena scrofa) in the studied area could have been caused by the anthropogenic factors on the fish community (overfishing and disturbance). However, the influence of the methodology of visual counts with defined and, for large fishes, relatively small, surface can not be excluded. The future use of the random visual census technique or the total count visual census technique could resolve this dilemma. The majority of numerously found epibenthic gobiids are connected with the availability of cracks and crevices, whereas poorly presented hyperbenthic wrasses (fam. Labridae) prefer dense cover of erected macroalgae or seagrass.
ACKNOWLEDGEMENTS
Diving assistance was provided by M. Arko Pijevac, C. Beriac and M. KirinCic. ! thank L. Lipej for his critical reading of the paper.
6
ANNALES • Ser. Iiist. nat. ■ 12 • 2002 • 1
Maicelo KOVAČIC: A VlSUAL CCNSUS Or TH£ CO.ASTAl FISM ASSEMBLACfl AT KOSTRENA (THE KVARNCR ARCA. CROATIA), \ .g	~~
VIZUALNO ŠTETJE PRIOBALNIH RIBJIH ZDRUŽB V KOSTRENI (KVARNER, HRVAŠKA)
Marcelu KOVAČiČ Prinodosbvni muzej Rijeka, RR-51000 Rijeka, t.orenzov proia? t E-matl: MArcflo.Kovaric@pubiic.srce.hr
POVZETEK
Za predhodni opis ribjih združb na štirih iokaliletah v Kostreni (Kvarner, Hrvaška) v poletnih mesecih (juliju in avgustu) leta 7999 je bila uporabljena metoda vizualnega štetja rib, in sicer modificirana stacionarna tehnika štetja (točkovna ali krožna točkovna metoda). Rezultati predhodnega opazovanja ribjih združb opravičujejo načrt ustanovitve zaščitenega območja na tej lokaliteti. Pričujoči podatki kažejo na presenetljivo visoko število ribjih vrst v primerjavi z drugimi objavljenimi rezultati vizualnih štetij v Sredozemlju, ki so bita pogosto opravljena na neprimerno večjih vzrocih in kombinirana z drugimi tehnikami vzorčenja. Zabeleženih je bilo 52 ribjih vrst, 42 med točkovnim Štetjem, druge pa naključno med potopi, ki jih je opravila skupinica potapljačev. Na morskem dnu, bogatem s Špranjami in drugimi ribjimi zavetišči, a brez gostega pokrova makroalg ali morske trave, so bile zabeležene mnoge male efibentoške vrste (družini Cobiidae in Blenniidae). Rezultati pričajo tudi o močnem vplivu sestave matične podlage in globine dna na ribjo skupnost - ali vsaj na sestavo ribjih vrst. Po tako imenovani grozdičasti analizi so bili primerki razvrščeni v pet habitatnih tipov, temelječih na podobnostih v značilnostih dna in globine. Parametri združb med posameznimi skupinami so se močno razlikovali.
Ključne besede: ribje združbe, jadransko morje, vizualno štetje
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ANNALES • 5er. hist, nat, ■ 12 • 2002 • 1
Marcelo KOVAÖC: A VISU Ai. CENSUS Of THE C.OASTAI. FISH ASSEMBLAGE AT KOSTRFNA 0HE KVARNEK AKtA, CROA1 ¡AI, 1 -8
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