An exploration of historical data suggested that eutrophication patterns might drive long-term fluctuations in Cystoseira populations along the west Istrian Coast (northern Adriatic Sea, Croatia). ...The regimes of northern Italian rivers, which flow approximately 100km west of the study area, mainly modulate the eutrophication levels of the northern Adriatic Sea. A regression of Cystoseira populations from the 1970s through the 1990s corresponded to increased levels of eutrophication in the study area. During the late 1990s, the density of sea urchins, which are efficacious macroalgal predators, decreased, likely due to an intense formation of pelagic mucilage aggregates that resulted in mass mortality episodes of macrozoobenthic species. During the 2000–2013 period, an oligotrophication of the northern Adriatic formed the basis for the recovery of Cystoseira taxa, whose abundances from 2009 to 2013 were similar to those characterising the most flourishing Mediterranean Cystoseira assemblages.
•Northern Italian rivers are the main source of nutrients for the northern Adriatic Sea.•Along the west Istrian Coast, Cystoseira regressed from the 1970s to the late 1990s.•Surveys performed during 2009–2013 revealed a substantial recovery of Cystoseira taxa.•Long-term changes in Cystoseira reflected variations in pelagic eutrophication levels.•The pelagic mucilage phenomenon could modify the structure of benthic assemblages.
•Port activities altered the composition of north Adriatic Cystoseira mixed stands.•The topography of the rocky bottom governed Cystoseira spp. demography.•C. corniculata and C. foeniculacea were the ...dominant species in control areas.•C. compressa and C. humilis were able to withstand in port areas.•Cystoseira spp. sensitivity to port activities was related to their growth patterns.
The effect of bottom topography on Cystoseira spp. was estimated along the west Istrian Coast (northern Adriatic Sea, Croatia) between 6 and 10m depth in off-port control areas and in ports of coastal cities. Two geomorphologic bottom types were considered: a stepped rocky bottom (T1, slope≈10°) and a flat rocky-sandy bottom (T2, slope≈4°). In control areas, Cystoseira spp. formed mixed stands composed of six species. The bottom topography strongly influenced C. corniculata (dominant on T1) and C. foeniculacea (dominant on T2). The response of C. barbata and C. spinosa to bottom topography varied among control areas, whereas C. compressa and C. humilis did not show topographic preferences. In ports, stands were mainly composed of C. compressa and C. humilis. The species C. barbata, C. corniculata, C. foeniculacea and C. spinosa were strikingly regressed, leading to a decrease in Cystoseira spp. total cover. However, they tended to be more frequent on T1 than on T2, which highlighted the role of bottom topography for their survival in adverse conditions. The capability of C. compressa and C. humilis to withstand moderate levels of anthropogenic pressure that is characteristic of west Istrian ports may well be related to their rapid growth and high recruitment rate.
The aim of the study was to explore the relationship between membrane-regulating functional lipids of three fucacean species and their associated epiphytic bacterial communities. The analyzed algae ...Treptacantha barbata, Carpodesmia crinita and Cystoseira compressa, formerly classified under the Cystoseira genus, are indigenous to the Adriatic Sea. The thalli of sampled Fucales species were divided into perennial and annual parts. T. barbata and C. crinita show high contents of mono- and polyunsaturated fatty acids but, however, show a clear distinction between branches, cauloids and apical parts. Along with the highest unsaturation degree (4.32), the C. crinita branches and apical parts demonstrated high proportion of both C18 and C20 polyunsaturated fatty acids, with eicosapentaenoic (C20:5 n-3) and arachidonic (C20:4 n-6) fatty acids up to 5.46% and 13.82%, respectively. The highest proportion of saturated fatty acids was found in thalli of C. compressa, particularly on cauloids and old branches (≥90%). The similarity profile routine analysis of fatty acids and microbial community structure has shown clear separation of the cauloids and apical parts from the branches of C. crinita and T. barbata. Based on the nonmetric multidimensional scaling analysis several representatives of the Gammaproteobacteria class, identified as Vibrionales (Vibrio), Cellvibrionales and Xanthomonadales, which contributed strongly to the separation of T. barbata apical parts and branches, C. compressa receptacles and C. crinita branches from the T. barbata cauloids and C. crinita apical parts and cauloids. The highest richness in polyunsaturated fatty acids, in particular C18:3(n-3), C20:4(n-6) and C20:5(n-3), was observed on branches, accompanied by a distinctive epiphytic microbial structure dominated by numerous representatives with potentially beneficial biological activity. The results showed a strong relationship between fatty acid profiles of the analyzed species and phycosphere community structure, underlining the host physiological condition in shaping the biological interactions and maintaining a healthy microbiome, as well as compiling the ecophysiological and molecular research in order to better assess the resilience of the ecosystem.
During the spring of 2016, benthic blooms of
(Ectocarpales, Phaeophyceae) producing voluminous mucilaginous aggregates frequently occurred at surveyed locations of the west Istrian Coast (northern ...Adriatic Sea, Croatia). In mucilage-affected macroalgal assemblages, the concentration of ammonium ranged from 50 to 300 μM. To investigate whether ammonium has the potential to harm fucalean species, a selected taxon,
was exposed to increased ammonium concentrations in laboratory conditions. Experiments revealed that exposure to 50 μM ammonium severely damaged the thalli while exposure to 300 μM caused complete necrosis of thalli in 2 days. These findings suggest that benthic algal blooms, enhanced by climate change and eutrophication, can negatively affect the populations of fucalean species due to production of ammonium during the decay of mucilaginous aggregates, causing thallus necrosis.
The northern Adriatic Sea represents the northernmost and thus the coldest biogeographic sector of the Mediterranean Sea. In 2004, the invasive green alga Caulerpa cylindracea was recorded for the ...first time in the northern Adriatic at a site of the west Istrian Coast. Until 2010, additional C. cylindracea mats have only formed up to 7 km northward from the first colonisation site. Subsequently, the alga was also recorded at sites widespread along the entire coast. Both the first 2004 colonisation event and the 2011–2014 colonisation of distant sites occurred during periods of winter seawater temperatures higher than 9 °C. In general, algal spreading was markedly slow. Approximately 10 years after the first record, C. cylindracea has affected less than 1% of the entire west Istrian coastline. The colonisation predominantly occurred in ports and urbanised bays (seaside resorts) suggesting that anthropogenic activities might enhance algal diffusion.
•Caulerpa cylindracea withstands cold northern Adriatic winter temperatures.•The algal spreading depends on long-term seawater temperature fluctuations.•C. cylindracea predominantly colonises locations subjected to anthropogenic pressure.•Both exposure to wave action and substrate type influence algal diffusion.•Along the west Istrian coast, C. cylindracea is mostly widespread up to 10 m in depth.
Metallothioneins content was investigated in digestive gland of two wild-caught Norway lobster Nephrops norvegicus populations from the Northern Adriatic Sea, in relation to body size, season and ...gender. Concomitant accumulation of cadmium, mercury, arsenic, lead, chromium and manganese, reactive oxygen species concentration and energy reserves in digestive gland were also assessed. While differences between genders were not recorded, metallothioneins content seasonal trends were affected by body size. Most of parameters displayed inconsistent trends across sampling sites. Significant correlation between metallothioneins content and cadmium, arsenic and mercury concentrations was recorded only for larger lobsters. A negative correlation of reactive oxygen species concentration and metallothioneins content was observed for small, but not large lobsters. Energy reserves, in particular lipids, could considerably influence biochemical and chemical parameters variations. The present results constitute the essential baseline for future studies aimed at evaluating the N. norvegicus health in relation to metal contamination of coastal sediments.
•Body size affected the seasonal trend of MTs content in lobster's digestive gland.•Gender had no influence on MTs content.•MTs content of larger lobsters was positively correlated to Cd, As and Hg concentration.•ROS level was negatively correlated to MTs content of small lobsters.•Lipids content was negatively correlated to MTs content and metals concentration.
Shell width and body live weight related to shell length of the endolithic bivalve Lithophaga lithophaga (date mussel) colonizing a specific habitat (vaults under boulders) formed by artificial and ...natural structures were examined. Artificial structures consisted of limestone boulders of a breakwater (Marina Rovinj, northern Adriatic Sea, Croatia) constructed 19 years before sampling of the date mussel. Date mussels' density (around 80 individuals per 0.1 m super(2)) did not differ between the two types of structure. However, the length frequency distribution in artificial structures (25 super(th) percentile = 3.20, median = 4.30 and 75 super(th) percentile = 5.10 cm) differed from that in natural structures (25 super(th) percentile = 3.66, median = 5.15 and 75 super(th) percentile = 6.20 cm) leading to a substantial difference in total biomass (0.3 and 0.8 kg per 0.1 m super(2) for artificial and natural structures, respectively). Parameter estimates of regression functions for width against length (linear function) and for live weight against length (allometric function) also significantly differed, indicating variations in date mussels' morphometry between the two types of structure. Analyses of variance did not detect differences in width or weight for date mussels in the length range from 3 to 3.5 cm. However, width (average plus or minus s.d., n = 18) of individuals in the range from 5.5 to 6 cm was significantly lower in artificial structures (1.46 plus or minus 0.13 cm) than in natural structures (1.66 plus or minus 0.10 cm). Consistent with this, live weight in artificial structures (8.36 plus or minus 1.17 g) was significantly lower than that in natural structures (12.33 plus or minus 1.48 g). It is suggested that these patterns reflect a growth rate of the date mussel that is higher in artificial than in natural structures. Information about date mussels' biometric patterns in different habitats is important in planning studies assessing the resilience capability of natural populations after illegal destructive harvesting, particularly as,such studies are lacking.Original Abstract: Istrazene su sirina ljusture i tezina zivog organizma u odnosu na duzinu ljusture endolitskog skoljkasa Lithophaga lithophaga (prstac) u specificnom stanistu (svodovi ispod blokova) sastavljenom od umjetnih i prirodnih struktura. Umjetne strukture su bile vapnenacki blokovi lukobrana (Marina Rovinj, sjeverni Jadran, Hrvatska), izgradjenog 19 godina prije uzorkovanja prstaca. Brojnost prstaca (oko 80 jedinki po 0.1 m super(2)) nije se razlikovala izmedju tipova struktura. Medjutim, raspodjela frekvencije duzina u umjetnim strukturama (25. percentil = 3,20, medijan = 4,30 i 75. percentil = 5,10 cm) razlikovala se od one u prirodnim strukturama (25. percentil = 3,66, medijan = 5,15 i 75. percentil = 6,20 cm) sto je dovelo do znacajne razlike u ukupnoj biomasi (0,3 kg po 0.1 m super(2) za umjetne i 0,8 kg po 0.1 m2 za prirodne strukture). Nadalje, procijenjeni parametri regresijskih funkcija sirine u odnosu na duzinu (linearna funkcija) i tezine u odnosu na duzinu (alometrijska funkcija) znacajno su se razlikovali, sto upucuje na morfometrijske razlike prstaca izmedju tipova struktura. Analizom varijance nije ustanovljena razlika u sirini ili tezini prstaca u rasponu duzine od 3 do 3,5 cm. Medjutim, sirina (aritmeticka sredina plus or minus s.d., n = 18) jedinki u rasponu od 5,5 do 6 cm bila je znacajno manja u umjetnim (1,46 plus or minus 0,13 cm) nego u prirodnim strukturama (1,66 plus or minus 0,10 cm). U skladu s time, i tezina jedinki u umjetnim strukturama (8,36 plus or minus 1,17 g) je bila manja nego u prirodnim strukturama (12,33 plus or minus 1,48 g). Pretpostavlja se da su navedene razlike bile posljedica vece brzine rasta prstaca u umjetnim nego u prirodnim strukturama. Informacije o biometrijskim karakteristikama prstaca u razlicitim stanistima su vazne za planiranje studija o obnovi prirodne populacije nakon nezakonitog destruktivnog sakupljanja, te takve studije zasada nedostaju.
Scale-based biometric relationships of
species were studied. All of the allometric relationships between size and biomass were significant (p<0.001) and volume estimated as the product of length (L) ...and circumference-squared (C
) was a better predictor of both wet biomass (WB) and dry biomass (DB) than L. The allometric exponent of the relationship between L and DB for five
species (0.238–0.297) was found to be close to the allometric exponent suggested to be universal for primary producers (0.25). The relationship between
spp. coverage (%; estimated in the laboratory for each species harvested within a reference quadrat in vertical projection) and WB was best expressed by a power function, while that between photographic cover (%; estimated in the field) and WB was asymptotic at 100% cover. The relationships between cover (%) (CVr) and coverage (%) (CVe) with WB pooled from an independent dataset were polynomial with comparable values up to 120 g WB. ANCOVA showed species-specific (e.g. between biomass and size) and species-independent (e.g. between biomass and coverage/cover, between DB and WB, and between DB and organic matter) relationships, indicating that non-destructive sampling in the genus is feasible when species and parameter are taken into account.
Badenian (Middle Miocene) transgressive deepening-upward successions located in the NE part of Mt. Medvednica (North Croatian Basin, Pannonian Basin System) unconformably overlie Mesozoic basement. ...Triassic and Upper Cretaceous limestone pebbles, cobbles, and boulders of the Badenian basal conglomerates display abundant in situ bivalve borings of
Gastrochaenolites
and sponge borings of
Entobia
. This
Gastrochaenolites
-
Entobia
ichnoassemblage is related to the
Entobia
subichnofacies of the
Trypanites
ichnofacies, characterizing littoral rocky-shore environments (wave-cut platforms and marine transgressive surfaces with a low or null rate of sedimentation).
Gastrochaenolites torpedo
,
Gastrochaenolites lapidicus
, and
Entobia
recorded in Badenian basal conglomerates (compared with modern Northern Adriatic rocky-shore environments), enabled more precise palaeoenvironmental interpretations. The occurrence of
G. torpedo
(produced by lithophaginid bivalves) on all sides of individual limestone lithoclasts in the Gornje Orešje basal conglomerate, coupled with truncation of the formation (possibly indicating multiphase colonization), reflect gravel transport, roll-over, overturning and erosion by wave action in high-energy rocky-shore settings. Gornje Psarjevo-2 basal conglomerate boulders were probably not subjected to significant movement and abrasion, as suggested by good preservation of both
G
.
lapidicus
(potentially produced by gastrochaenid bivalves), associated
G
.
torpedo
, as well as abundant shallow
Entobia
borings. The Badenian
Gastrochaenolites
-
Entobia
ichnoassemblage also could be the result of a composite development. However, direct cross-cutting relationships between
G
.
torpedo
and
G
.
lapidicus
and/or
Entobia
were rarely observed. In addition, Badenian boring tracemakers might have coexisted at the same water depth. Northeast Mt. Medvednica Badenian successions probably formed during different Central Paratethys transgressive pulses (NN5 and NN6 Zones). However, exact timing of Badenian transgressions, stratigraphic correlations and tectono-eustatic implications are unresolved, due to sparsely integrated biostratigraphic and high-precision geochronological studies of Early–Middle Miocene North Croatian Basin deposits and due to the absence of a uniform biostratigraphic zonation and regional chronostratigraphic division of Central Paratethys.
In October 2014, a blue runner (Caranx crysos) was caught by a professional fisherman in waters off St. Eufemija Point (west Istrian Coast, northern Adriatic Sea, Croatia). This is the second ...recorded blue runner in the northern Adriatic Sea, which represents the northernmost biogeographic sector of the Mediterranean Sea. Recently, blue runners were recorded in the southern and central Adriatic Sea, suggesting that the central Mediterranean C. crysos is expanding its area of distribution throughout the Adriatic Sea. As a point of interest, this most recent specimen presented an unusual meristic feature: the number of spines of its first dorsal fin was VI, whereas it is generally recognised that the number of such spines characteristic for this species is VIII. Species identity of the specimen was confirmed by DNA sequence analysis of the mitochondrial cytochrome c oxidase subunit I (COI) gene. In addition, we provided the first report of C. crysos mitochondrial 16S ribosomal RNA (16S rRNA) partial sequence.Original Abstract: U listopadu 2014. godine, ribu plavi trkac (Caranx crysos) je ulovio profesionalni ribar nekoliko stotina metara van rta Sv. Eufemija (zapadna obala Istre, sjeverni Jadran, Hrvatska). Ovo je drugi po redu nalaz ribe plavi trkac koja je ulovljena u sjevernom Jadranu, sto predstavlja najsjevernije biogeografsko podrucje sredozemnog mora. Nedavno ova vrsta je zabiljezena u juznom i srednjem Jadranu sto ukazuje da se populacija C. crysos iz sredisnjeg Sredozemnog mora prosiruje u Jadranskom moru. Razmatrani primjerak je pokazao neobicnu meristicku znacajku: broj bodlji u prvoj lednoj peraji je VI, dok je opcenito za ovu vrstu prihvaceno (priznato) VIII bodlji. Identitet vrste potvrden je analizom mitohondrijske DNA sekvence za pod-jedinicu I gena citokrom c oksidaze (COI). U ovom radu takoder je po prvi put analiziran dio mitohondrijske DNA sekvence odgovorne za kodiranje 16S ribosomske RNA (16S rDNA) kod vrste C. crysos.
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