BIOLOGICAL AND ECOLOGICAL CHARACTERISTICS OF VARIEGATED SCALLOP Chlamys varia (LINNAEUS, 1758.) – AS THE BASIS FOR FARMING

Školjkaši porodice češljača (Pectinidae) su vrlo cijenjeni među svjetskim potrošačima. Stoga se u razvoj tehnologije uzgoja češljača ulažu veliki napori. Diljem svijeta koriste se lokalne vrste porodice Pectinidae, ali i uvode nove, najčešće japanska kapica (Patinopecten yessoensis Jay, 1858.). Na tržište u Hrvatsku dolazi 16 vrsta školjkaša s istočnog dijela Jadrana, ali se uzgajaju samo dvije vrste (dagnja i kamenica). Mala kapica Chlamys varia nalazi se na mnogim lokalitetima, često na postojećim uzgajalištima školjkaša. Brojni svjetski autori smatraju da uzgoj male kapice treba temeljiti na mlađi uzgojenoj u mrjestilištu jer je prihvaćanje mlađi na kolektore nedovoljno uspješno i ovisno o varijacijama ekoloških čimbenika. Istraživanjem reproduktivnog ciklusa male kapice, došlo se do zaključka da se u prirodnim uvjetima najčešće mrijesti dva puta godišnje, a vrijeme mrijesta se mijenja ovisno o lokalitetu i od godine do godine.Pectinides are a highly regarded sea product among the consumers. Huge efforts are being made for the development of farming technology. All around the world the local species of the Pectinidae family are being consumed along with some newly introduced species as for example Japanese scallop (Patinopecten yessoensis Jay, 1858). Althougt there are 16 species of shellfish from eastern Adriatic that are offered in Croatian markets, only two species are being farmed. Chlamys varia (variegated scallop) is often found in many locations, most often where the s alredy egsist shellfish farming. Many authors believe that farming must be conducted in the hatcheries since the spat settlement on the collectors has proven unsuccessful and dependent of many environmental factors. The research of hatchery cultivation of this species has been described. In most areas where the reproductive cycle has been studied there appear to be two main periods of spawning each year, but the timing can differ between areas, and between years

THE PROBLEM OF PLASTIC WASTE AND MICROPLASTICS IN THE SEAS AND OCEANS: IMPACT ON MARINE ORGANISMS

Globalni problem današnjice je velika količina otpada u morima i oceanima, ponajprije plastičnog otpada. Procjenjuje se da svake godine putem riječnih tokova u mora i oceane dospije 1,25 do 2,41 milijuna tona plastike. Otpad predstavlja veliki problem morskim organizmima, uzrokujući zaplitanje, gušenje, davljenje, pothranjenost i smrt. 1972. godine otkriven je problem mikroplastike, čestica plastike koje su manje od 5 mm. Takve čestice na sebe vežu patogene mikroorganizme. Sve više mikroplastike pronalazi se u želucima riba, ali i u školjkašima koji se hrane filtriranjem mora. Morske životinje unose plastiku u svoj organizam, naposljetku putem hranidbenog lanca dolaze i do čovjeka. Osim toga, plastika otpušta kemijske spojeve za koje još nije dovoljno dokazano kako djeluju na morske organizme, ali i na ljude. Mnoge svjetske i državne organizacije navode rješenja putem recikliranja plastičnog otpada, kao i smanjivanja same proizvodnje plastičnih materijala te informiranja javnosti o navedenom problemu.A global problem of today is the large amount of waste in the seas and oceans, primarily plastic waste. It is estimated that every year 1.25 to 2.41 million tons of plastic material is being carried by rivers into the seasand oceans. Waste is a major problem for marine organisms, causing entanglement, choking, strangulation, malnutrition and death. In 1972 the problems caused by microplastics, particles smaller than 5 mm, were first observed. Such particles bind pathogenic microorganisms onto their surface. Increasing quantities of microplastics have been found in the stomachs of fish, and also in shellfish that feed by filtering sea water. Ingested by marine organisms, such plastics may eventually passthrough the food web and can end up ingested by humans. In addition, plastic releases chemical compounds whose effect on marine organismsand humans has still not been studied. Many international and state organizations offer solutions through recycling plastic waste, as well as reducing the production of plastic materials and informing the public about the problem

Length-Weight Relations and Monthly Occurrence of Juvenile Fish Species from the Donji Molunat Bay, Croatia (South-East Adriatic Sea)

Length-weight relations (LWR) and monthly occurrence are presented for juvenile fish, sampled from April to December 2018. in the of Donji Molunat bay, Croatia. From total number of 1448 caught fish of 30 fish species, 699 individuals of 16 fish species: Atherina hepsetus, Chromis chromis, Coris julis, Diplodus annularis, Gobius bucchichii, Microlipophrys canevae, Oblada melanura, Oedalechilus labeo, Pagellus acarne, Sarpa salpa, Serranus scriba, Siganus luridus, Symphodus cinereus, Symphodus doderleini, Symphodus ocellatus and Symphodus rostratus were analysed. Two parameters were measured: total length (TL) using precision ruler to the nearest 0.1 cm, and weight (W) using digital balance to the nearest 0.1 g. The b values ranged from 2.731 to 3.427, with median 3.0305. This study provides the first LWRs for juvenile fish species in the Donji Molunat bay, as that it can serve as a tool used for future reference

DJELOVANJE LHRHa ZA IZAZIVANJE OVULACIJE PRI RAZLIČITIM VELIČINAMA OOCITA I KVALITETE OPLOĐENIH JAJAŠACA U UŠATE OBLADA MELANURA (LINNAEUS, 1758)

The objective of this study was to evaluate the effects of oocyte size and luteinizing hormone releasing hormone analogue (LHRHa) on ovulatory success in artificial fertilization. Vitellogenic females with maximum oocyte diameters 400-550 µm were repeatedly injected with LHRHa (20 µg kg-1 per injection). Fish with maximum oocyte diameters 500 µm spawned within 48-54 h. These results demonstrate that injected LHRHa is effective for ovulation of saddled bream with maximum oocyte diameters >500µm.Cilj ovog rada bio je utvrditi veličinu oocita za uspješno djelovanje hormona LHRHa i uspješnost umjetne oplodnje nakon hormonskog tretmana.Vitelogene ženke s promjerom oocita 400-550 µm injektirane su hormonom LHRHa 20 µg/kg težine. Ženke s najvećim brojem oocita promjera500 µm ovulirale u roku 48 -54 sati nako ntretmana s LHRHa. Ovaj rad pokazuje da je hormon LHRHa djelotvoran za izazivanje ovulacije kod ušate kada se injektira pri veličini oocita iznad 500 µm

Fan mussel Pinna nobilis Linneaus, 1758 spat collection on \u27\u27Christmas tree\u27\u27 rope in the Mali Ston Bay area (South Adriatic Sea)

During November 2006 on a 500 m long experimentally placed \u27\u27Christmas tree\u27\u27 rope collector for juvenile mussels (Mytilus galloprovincialis Lamarck, 1819) placed the previous year a significant number of juvenile fan mussels (Pina nobilis Linnaeus, 1758) were observed. Live juvenile individuals (N=322) of P. nobilis with shell length from 17 to 93 mm were found in two sampling events. All juvenile fan mussels were found exclusively on deeper parts of the mussel rope. Observed population density was from 6 to 43 individuals per meter of the rope collector. The 120 smallest juveniles of P. nobilis were separated for the purpose of monitoring the growth rate in suspension, and the remaining juveniles were placed in the natural environment

The Size Driven Variations in Physiological Responses of the Bearded Horse Mussel Modiolus barbatus and the Noah’s Ark Shell Arca noae

Bearded horse mussel and Noah’s ark shell are sometimes observed to live together in groups. Oxygen consumption, ammonia excretion and clearance rate were investigated on these species under laboratory conditions considering different size of individuals divided into three size groups (less than 25 mm; 25 to 50 mm and larger than 50 mm). Body size of both species significantly influenced oxygen consumption, ammonia excretion and clearance rate of the Noah’s ark shell. In both species, respiration and clearance rate decreased with body size while excretion rate increased with body size. For Noah’s ark shell groups of 25 to 50 mm and smaller than 25 mm, the atomic ratio between oxygen consumption and ammonium excretion i.e. O:N ratio was detected to be greater than 30. The same applies to a group of the bearded horse mussels smaller than 25 mm. Animals of both species larger than 50 mm have O:N ratio smaller than 30 indicating use of proteins as metabolic substrate, compared to use of lipids and carbohydrates in younger animals

THE QUANTITATIVE-QUALITATIVE CONTENT OF JUVENILE FISH AT THE MOUTH OF THE RIVERS NERETVA AND MALA NERETVA DURING THE SUMMER-AUTUMN PERIOD

Tijekom kolovoza, listopada i prosinca 2008. na postajama uz ušće Neretve i ušće Male Neretve istraživane su promjene sastava i brojnosti vrsta lokalnih ihtiozajednica. Pridnenom mrežom potegačom prikupljeno je ukupno 690 jedinki od čega 437 na ušću Neretve, a 253 na ušću Male Neretve. Jednike su razvrstane ih u 14 porodica i 19 vrsta. Najzastupljenije vrste u ukupnom ulovu pripadaju porodicama Atherinidae (40 %), Mugilidae (15,79 %), Gobiidae (15,50 %) i Sparidae (13,04 %). Margalefov indeks bogatstva vrsta je veći na područjima u kojima obitava veći broj vrsta, a utvrđen je od 1,66 u kolovozu do 4,13 u listopadu, dok je prema Simpsonovom indeksu najveća raznolikost od 0,393 zabilježena u prosincu i najmanja od 0,923 u listopadu. Najviša vrijednost Shannon Wienerovog indeksa od 1,18 je utvrđena u prosincu, a najniža u listopadu (0,36) jer su gotovo 90 % ulova predstavljale samo dvije vrste. Pielouv indeks, koji brojčano opisuje raznolikost ihtiocenoza, bio je od 0,14 u listopadu do 0,74 u prosincu. Istraživane postaje s obzirom na sastav vrsta pokazuju velike sličnosti, dok su razlike u kvantitativnoj strukturi. Postaja ušće Male Neretve je bogatija vrstama u odnosu na postaju ušća Neretve na kojoj nailazimo na manji broj vrsta, ali veću brojnost jedinki.A study was carried out on the changes in content and abundance of local juvenile fish community species at stations along the mouth of the Rivers Neretva and Mala Neretva during August, October and December 2008. A total of 690 specimens were collected using a small coastal trawl, out of which 437 were collected at the mouth of the River Neretva and 253 at the mouth of the River Mala Neretva. The specimens were categorized into 14 families and 19 species. The most abundant species from the total catch belonged to the families Atherinidae (40%), Mugilidae (15.79%), Gobiidae (15.50%) and Sparidae (13.04%). The Margalef index on specie richness was greater in the regions inhabited by larger numbers of species, ranging between 1.66 in August and 4.13 in October, wheras the highest diversity ranging between 0.393 in December and 0.923 in October was noted using the Simpson index. The highest value using the Shannon Wiener index was 1.18 in December and the lowest at 0.36 was in October, as almost 90% of the catch consisted of only two species. The Pielou index, which describes the variety of ichtiocenoza numerically, ranged between 0.14 in October and 0.74 in December. The stations investigated showed great similarities considering specie content, wheras there were differences in quantitative structure. The station at the mouth of the River Mala Neretva was richer in species as compared to the station at the mouth of the River Neretva, where we came across a smaller number of species, but a greater number of specimens

BIOLOGICAL AND ECOLOGICAL CHARACTERISTICS OF VARIEGATED SCALLOP Chlamys varia (LINNAEUS, 1758.) – AS THE BASIS FOR FARMING

Školjkaši porodice češljača (Pectinidae) su vrlo cijenjeni među svjetskim potrošačima. Stoga se u razvoj tehnologije uzgoja češljača ulažu veliki napori. Diljem svijeta koriste se lokalne vrste porodice Pectinidae, ali i uvode nove, najčešće japanska kapica (Patinopecten yessoensis Jay, 1858.). Na tržište u Hrvatsku dolazi 16 vrsta školjkaša s istočnog dijela Jadrana, ali se uzgajaju samo dvije vrste (dagnja i kamenica). Mala kapica Chlamys varia nalazi se na mnogim lokalitetima, često na postojećim uzgajalištima školjkaša. Brojni svjetski autori smatraju da uzgoj male kapice treba temeljiti na mlađi uzgojenoj u mrjestilištu jer je prihvaćanje mlađi na kolektore nedovoljno uspješno i ovisno o varijacijama ekoloških čimbenika. Istraživanjem reproduktivnog ciklusa male kapice, došlo se do zaključka da se u prirodnim uvjetima najčešće mrijesti dva puta godišnje, a vrijeme mrijesta se mijenja ovisno o lokalitetu i od godine do godine.Pectinides are a highly regarded sea product among the consumers. Huge efforts are being made for the development of farming technology. All around the world the local species of the Pectinidae family are being consumed along with some newly introduced species as for example Japanese scallop (Patinopecten yessoensis Jay, 1858). Althougt there are 16 species of shellfish from eastern Adriatic that are offered in Croatian markets, only two species are being farmed. Chlamys varia (variegated scallop) is often found in many locations, most often where the s alredy egsist shellfish farming. Many authors believe that farming must be conducted in the hatcheries since the spat settlement on the collectors has proven unsuccessful and dependent of many environmental factors. The research of hatchery cultivation of this species has been described. In most areas where the reproductive cycle has been studied there appear to be two main periods of spawning each year, but the timing can differ between areas, and between years

The Problem of Plastic Waste and Microplastics in the Seas and Oceans: Impact on Marine Organisms

A global problem of today is the large amount of waste in the seas and oceans, primarily plastic waste. It is estimated that every year 1.25 to 2.41 million tons of plastic material is being carried by rivers into the seas and oceans. Waste is a major problem for marine organisms, causing entanglement, choking, strangulation, malnutrition and death. In 1972 the problems caused by microplastics, particles smaller than 5 mm, were first observed. Such particles bind pathogenic microorganisms on to their surface. Increasing quantities of microplastics have been found in the stomachs of fish, and also in shellfish that feed by filtering sea water. Ingested by marine organisms, such plastics may eventually pass through the food web and can end up ingested by humans. In addition, plastic releases chemical compounds whose effect on marine organisms and humans has still not been studied. Many international and state organizations offer solutions through recycling plastic waste, as well as reducing the production of plastic materials and informing the public about the problem

IMPACT OF OOCYTE SIZE ON LHRHa INDUCED OVULATION AND FERTILIZED EGG QUALITY IN SADDLED BREAM OBLADA MELANURA (LINNAEUS, 1758)

The objective of this study was to evaluate the effects of oocyte size and luteinizing hormone releasing hormone analogue (LHRHa) on ovulatory success in artificial fertilization. Vitellogenic females with maximum oocyte diameters 400-550 µm were repeatedly injected with LHRHa (20 µg kg-1 per injection). Fish with maximum oocyte diameters 500 µm spawned within 48-54 h. These results demonstrate that injected LHRHa is effective for ovulation of saddled bream with maximum oocyte diameters >500µm