Benthic fishfauna on hard substrate of the Northeastern Ligurian Sea Presented by Maricela and Pierre in preparation of the Marine Lab Excursion in Summer 2000 Content: 1. The benthic environment 2. Bony fish morphology 3. Families and their species 4. Interactive Quiz 1. Benthos - Hard substrate or secondary hard substrate Hard substrate is generally grouped into primary and secondary hard substrate. In any case, due abiotic conditions, these environments are intensely structured. (Primary) Hard substrate: Mostly found along shorelines battered by strong currents and intense wave and tidal action, they remain free from sediments and other influences that would soften its appearance. Offering the bare rocky substrate to a wide selection of sedentary organisms (flora and fauna), persistent competition among species for empty space generates a rich diversity which themselves offer a new habitat for benthic invertebrates and fish. Secondary Hard Substrate: This substrate includes particles of organic and inorganic matter that accumulate in a loose unconsolidated form of biogenous (e.g. reef building corals), lithogenous or cosmogenous origin; usually beyond the compensation depth (aphotic or mesopelagic zone). Huge number of micro-organic debris that have slowly accumulated on the ocean floor (e.g. foraminifera silica-made, diatoms of cooler waters w/ silica housing), and others join with detrital products of disintegration of preexisting rocks and of volcanic ejecta, runoff by rivers, or glaciers; redistribution through waves and currents including relocation of desert sand by wind into the sea. Under certain circumstances, such sediments can harden into a compact conglomerate, thus providing a new nesting substrate. Other means of substrate formation are displayed by the tube worms of the phylum annelids. They secrete the leathery or calcareous tubes in which they live and extend only their feathery tentacles to strain food from the water. It is this tube that provides the substrate required for minute sedentary organisms. Depending upon the inclination of the substrate, abiotic factors such as light and current do influence species composition. A flat lagoon with an intense influx of solar radiation generates a somewhat different climax population regarding species composition, that a sharply falling drop off or even an underwater cave. The lower section of such a steep shoreline usually gives way to a more or less inclined slope, in which larger blocks of rock and pebble can accumulate. In general, at the base of slopes, large areas of flat and sand covered planes finally substitute the rocky substrate to form the sandy or muddy environment required for yet another vast group of bottom dwelling organisms. On hard substrate, a sheer endless diversity found on hard substrate culminates in a microcosmic array of both sedentary and mobile organisms. Initially, algae pioneer a bare rock, followed by more sophisticated secondary species, like sponges, bryozoa, anemones, etc.) To enable growth and reproduction, sedentary organisms evolved special techniques to guarantee their survival; the most common way to do so is achieved by stretching out their tentacles into the passing water currents; the size and strength of these tentacles already provide some clues about the source and type of captured organisms the animal feeds on. Caryophyllidae are the few hard coral building cinidaria present in the Mediterranean Sea. They feed on microscopic organisms in which the individual polyps of the colony represent the capturing entities. Hard substrate provides the perfect settling ground for other invertebrates, like the stalkless free moving crinoidea Antedon mediterranea (echinodermata), or territorial vertebrates like the Gobeiidae and Blenniidae. http://biophysics.sbg.ac.at/protocol/seminar.pdf 2. Bony Fish Characteristics of bony fish (Osteichtyes) Well-developed bony scales usually present. Primitive species retain electroreceptive organs, but these are lost in most contemporary species. The deeper skeleton always contains some bone; in most species it is nearly completely ossified. Lungs or a swim bladder are present, except in a few bottom-dwelling species in which they have been secondarily lost. The body is more buoyant than in cartilaginous fishes, and the tail has become homocercal in most living species. The gill pouches open into a common chamber covered by an operculum. The intestinal spiral valve is absent in all but the most primitive species. Surface area is increased by longer, coiled intestine and by pyloric ceca. The sperm duct usually bypass the kidneys and lead directly to the cloaca; eggs are discharged directly into the oviducts. Most species are oviparous and fertilization is external. The copulatory organ of the few viviparous species with internal fertilization is a modified part of the anal fin. Fish morphology 1 Operculum Kiemendeckel 2 Lateral line Seitenlinie 3 Pelvic fin Bauchflosse 4 Pectoral fin (P) Brustflosse 5 Dorsal fin 1 (DI) Rückenflossen 6 Dorsal fin 2 (DII) 7 Anal fin (A) Afterflosse 8 Caudal fin Schwanzflosse 9 Anus After e.g. D: X + 15-16 15-16 soft finrays 10 spinous finrays Dorsalis fin http://biophysics.sbg.ac.at/protocol/seminar.pdf Scales Cycloid Ctenoid Scales of modern bony fishes are present in various characteristic displays- Literature Dorit, R., Walker, W., Barnes, R.; (1991); Zoology; Saunders College Publishing - USA. Patzner, R; Moosleitner, H; (1999); Meerwasseratlas Band 6; Mergus Verlag; Melle - FRG. Patzner, R; Moosleitner, H; (1995); Unterwasserführer Mittelmeer - Fische; Delius Klasing Edition Naglschmid; FRG. Whitehead, et al., (1984); Fishes of the North-eastern Atlantic and the Mediterranean; Vol I, II, III; United Nations Educational, Scientific and Cultural Organization; The Chaucer Press, Ltd, Bungay - UK. Ahnelt, Harald; 1990; Chromogobius quadrivittatus, Chromogobius zebratus and Zebrus zebrus (Piesces, Gobiidae): Erstnachweise für Korsika (Frankreich) und sardinien (Italien); Ann, Anturhist. Mus. Wien; 91; B; 27-41 - AUT. Heymer and C.-D. Zander; (1978); Morphology and ecology of Gobius vittatus Vinciguerra, 1833, and ist possible mimicry relationship to Blennius rouxi Cocco, 1833 in the Mediterranan; Sonderdruck aus Z.f. zool. Systematik u. Evolutionsfoschung; Band 16, Heft 2, S. 132-143; AUT Patzner, Robert A.; 1999; Habitat utilization and depth distribution of small crytobentic fishes (Bleniidae, Gobiesocidae, Gobiidae, Tripterygiidae) in Ibiza (western Mediterranean Sea); Environmental Biology of Fishes 55: 207-214; Kluwer Academic Publishers - NL Patzner, R. und Moosleitner, H., (1997); Das Acquarium; SBG - AUT Die Grundeln des Mittelmeeres; Nr. 332. Die Grundeln des Mittelmeeres; Teil 1&2: Große Grundeln des Hartbodens (1&2); Nr. 335 & 336 Exkursionsberichte Meeresbiologischer Kurs Giglio (Italien); Leiter: R. Patzner; (1996); BUFUS Info, Heft 19 - AUT Exkursionsberichte Meeresbiologischer Kurs Giglio (Italien); Leiter: R. Patzner; (1998); BUFUS Info, Heft 23 – AUT Related sites on the www: A Global Information System on Fishes http://www.fishbase.org/search.cfm http://biophysics.sbg.ac.at/protocol/seminar.pdf 3. Selected benthic fish of the Ligurian Sea Family Anthiidae (Serranidae) Rather small-sized fishes. Body rather deep. Eye large, opercle with 3 flat spines; preopercle finely serrate. A few cannine teeth at the front of both jaws and a distinctive pair of cannines on sided of lower jaw. Dorsal fin single; pelvic fin elongate; caudal fin lunate. Scales large, mostly ctenoid. Lateral line running close to base of dorsal fin separated by 2-3 scale rows. Color usually red, orange, or yellow. Scientific name Anthias anthias Common name Swallowtail sea perch / Roter Fahnenbarsch Description Diagnosis: body rather deep, its depth 2.5 times in standard length. DX+15, third spine elongate; AIII+7; pelvic fins much longer than pectoral fins; caudal fin with acute lobes, lower longer than upper (heterocerk). Lateral line complete, ending at vase of caudal fin. Large ctenoid scales, 36-39 in lateral line. Color: red or pink, three yellow lines on sides of head; often brownish blotches on back. Size: up to 27cm; SL usually 12-18cm. Habitat Rocks, gravels, submarine caves on continental shelf and upper slope to about 200m. Rare in shallow waters. Nocturnal. Deep rock and coral; Frequency 1 2 3 444 555 common Behavior No data available Food Crustaceans, small fishes. Reproduction Spring and summer, with local variations. Oviparous with pelagic eggs. Protogynous Fm108 (Image: R.Patzner) http://biophysics.sbg.ac.at/protocol/seminar.pdf Family Apogonidae More or less elongate and rather small-sized fish. Eye very large, preopercular edge smooth or serrated, preceded by a parallel ridge; at least 1 opercular spine . Mouth large, oblique, lower jaw often prominent; teeth usually villifrom on jaws, vomer and often palatines; sometimes cannines. Two dorsal fins well separated. All members are carnivorous and oviparous. Scientific name Apogon imberbis (A. rex mullorrum) Common name Cardinal fish / Meerbarbenkönig Description Diagnosis: body ovate, compressed; head large; eye very large, much greater than snout; preopercular edge only slightly serrated, preopercular ridge smooth, mouth large, oblique, lower jaw slightly protruding; teeth very small, in villiform bands in jaws, on vomer and palatines. D1 VI; D2 I+9-10; A II+8-9; pectoral fin long, reaching at least origin of anal fin; caudal fin slightly emarginate. Large ctenoid scales, 22-30 in lateral line.