Ljubičasti splavar Janthina janthina (Linnaeus, 1578) (Mollusca: Gastropoda) opet plovi u Jadranu oko Lokruma

A specimen of the violet snail Janthina janthina (Linnaeus, 1578) was collected in Portoč Bay, Lokrum Island, in May 2016, during the beach cleanup and removing of marine debris drift arising from strong winds. The first record of the raft snail J. janthina along the eastern Adriatic coast was also noticed in the area of Lokrum Island in the middle of the 19th century.Kućica ljubičastog splavara Janthina janthina (Linnaeus, 1578) prikupljena je u uvali Portoč na otoku Lokrumu u svibnju 2016. tijekom uklanjanja otpada naplavljenog jakim vjetrom. Prvi nalaz puža J. janthina na istočnojadranskoj obali zabilježen je također u području otoka Lokruma sredinom 19. stoljeća

Rayed pearl oyster Pinctada radiata (Leach, 1814) (Bivalvia: Pteriidae) in the eastern Adriatic Sea – recent observations

Adriatic Sea as a part of the Mediterranean is settled by many introduced species which extend their range northward. Among them is the rayed pearl oyster Pinctada radiata, a mollusk of Indo-Pacific origin that colonises habitats throughout the Mediterranean. P. radiata established a population in a fish farm on the island of Mljet in the Adriatic Sea, which was observed in 2017. To determine the status of the population, 48 specimens of P. radiata were randomly sampled from the ropes of a fish farm in 2019. Morphometric parameters were determined using a digital calliper. The recorded parameters showed that shell height ranged from 50.55 mm to 72.98 mm, shell length from 46.66 mm to 71.15 mm, and shell width from 19.98 mm to 58.54 mm. During additional visual survey in 2020 the presence of the spat within population at Mljet fish farm was not observed. It appears that only adult specimens are present, and it is unclear if the population is reproducing. In addition, P. radiata spat was observed in the shallow waters of Lokrum Island in 2021 and 2022, indicating the possibility of survival of larvae naturally dispersing from pre-existing populations. An adult specimen of P. radiata was also observed in Mali Ston Bay on two occasions, in 2009 and 2021. P. radiata, a highly adaptable species that tolerates a wide range of environmental factors, has successfully colonised new habitats

Myriophyllum heterophyllum Michx. (Haloragaceae) u Hrvatskoj

In Europe, Myriophyllum heterophyllum Michx. (Haloragaceae) has had the status of invasive species in freshwater ecosystems since 2012. During phytosociological research in the Neretva River Delta in July 2016, we noted a high coverage of species Myriophyllum heterophyllum within vegetation of rooted leaf-floating macrophytes of the Nymphaeion albae Oberd. 1957 alliance (the order Potamogetonetalia Koch 1926). In this paper, alongside the finding of the new locality with M. heterophyllum in Croatia, its phytosociology is reported.Sjevernoamerička vrsta Myriophyllum heterophyllum Michx. (Haloragaceae) u Europi ima status invazivne vrste od 2012. godine. Tijekom fitocenoloških istraživanja u delti Neretve u srpnju 2016., utvrdili smo visoku pokrovnost vrste Myriophyllum heterophyllum u vegetaciji zakorijenjenih makrofita sveze Nymphaeion albae Oberd. 1957 (Potamogetonetalia Koch 1926). Prema dosadašnjim podacima, to je drugi nalaz te vrste u Hrvatskoj

The Decay of Wooden Wreck at Two Sites in Dubrovnik Area

The preparation is presented of underwater wood, wood identification, wood properties and FT-IR analysis. Two samples of Oak (Quercus petraea Liebl.; Quercus robur L.) were analyzed from two sites in Dubrovnik area, island Koločep and Molunat. This paper presents the preparation of underwater wood, wood identification, wood roperties and FT-IR analysis. Three section of wood, cross section, radial section and tangential section made for microscopis hardwood and softwood identification. The best two samples are assumed to be Sessil oak (Quercus petraea Liebl.) and Pedunculate oak (Quercus robur L.)

Potential for acclimation of banded-dye murex, Hexaplex trunculus (Linnaeus, 1758) after long-term exposure to low pH

Previous work on ocean acidification highlighted contrasting response between marine species and population. This so-called species-specific response was hypothesized to be partly a consequence of local adaptation to the present range of natural variability in the carbonate chemistry. Under that hypothesis, species tolerance threshold should be correlated to its environmental pH niche. This paper aims to evaluate shell growth rate of Hexaplex trunculus, an important predatory gastropod in benthic communities of Mali Ston Bay. A long-term experiment (310 days) was designed to test a range of pH treatments covering present and future pH levels relevant in the context of future ocean acidification (7.95-7.22 pHT) at the sampling site. Sex had an effect on the shell growth rate irrespective of pH, and was only significant after 236 days. As growth rate in all pH treatments followed seasonal patterns correlating to changes in seawater temperature, the data were divided into 3 time periods. A positive relationship between shell growth rate (SGR, mm day-1) and pH was observed for the period 1-59 days (temperature ranging between 26.5 & 18.8 °C), whereas SGR decreased significantly with pH for the following period (60-236 days, temperature ranging between 20.6 & 8.5 °C). After 236 days (temperature ranging between 27.5 & 14.1 °C), there was no significant difference in SGR among pH. Similar temperature was experienced between the first and third period and the difference in response could be explained as a consequence of an acute negative response versus a longer exposure indicating possible potential for acclimation. Our results highlight the modulating effect of temperature and the importance of long-term experiments to better assess impacts of ocean acidification on marine organisms

The Contribution of Scientific and Historical Data to the Conservation and Management of the Island of Lokrum Marine Area

In order to collect relevant data on the status of habitats and species which could be applied in the management of the Lokrum marine area, the paper shows the stages in the research of this area. Reliable published data, travelogues and scientific papers, were analysed and taken into consideration to propose the guidelines for managing primarily the marine area of the Natura 2000 site Lokrum

UČINAK SUSTAVA ZA TRETIRANJE VODENOG BALASTA NA PREŽIVLJAVANJE PRIRODNIH POPULACIJA ZOOPLANKTONA U PLOVIDBENIM UVJETIMA NA BRODU „NAŠE MORE“

Introdukcija alohtonih vrsta predstavlja vrlo opasnu prijetnju svjetskoj bioraznolikosti. Više je vektora unosa morskih alohtonih vrsta u nova staništa, a najizraženiji su akvakultura i brodski promet, tj. obraštaj na oplati broda i vodeni balast. U ovom radu opisano je testiranje sustava za obradu vodenog balasta u plovidbenim uvjetima na brodu „Naše more“ u Šibenskom zaljevu i Omišaljskoj uvali. Određivao se učinak ciklonske separacije u hidrociklonu, zasebno i u kombinaciji s ultraljubičastim zračenjem u UV reaktoru, na preživljavanje zooplanktonskih organizama. Morska voda je usisavana brodskom pumpom i propuštana zasebno kroz hidrociklonski klaster, te kombinirano kroz hidrociklonski klaster i UV reaktor u 3 uzastopna ciklusa. Dobiveni su gotovo identični rezultati u pokusima s UV zračenjem kao i pokusima bez UV zračenja, što ukazuje na zadovoljavajuću učinkovitost mehaničkog tretiranja u hidrociklonu na preživljavanje zooplanktona. Prikupljeni su i analizirani kontrolni uzorci iz okolnog mora, uzorci separirani hidrociklonima kao i oni koji su prošli kroz sustav za tretiranje i sakupljeni u tankove na brodu koji su predstavljali balastne tankove. Usporedbom kontrolnih uzoraka iz okolnog mora i tretiranih uzoraka iz tankova na brodu zaključeno je da je ciklonskom separacijom odstranjeno 62,7 % do 54,5 % organizama, što znači da je u pokusima kroz hidrociklone propušteno i sakupljeno u tankove na brodu 37,3 % do 45,5 % jedinki, od čega je bilo 4,7 % do 32,8 % živih. Nakon 8 sati udio živih jedinki u odnosu na ukupni broj u okolnom moru bio je 14,9 %, a nakon 24 sata svega 1,8 %. Provedenim pokusima dokazana je i razrađena uspješna upotreba sustava za obradu vodenog balasta za inaktivaciju zooplanktonskih organizama u morskoj vodi

Raman Spectroscopy Techniques and Technology as a Tool in Environmental Water Analysis

Although the normal Raman scattering effect is inherently weak in diluted solutions such as environmental waters and dedicated enhancing techniques are already suitable for trace analysis of many harmful compounds, pollutants, toxins, and other species from aquatic environments, here we demonstrate how Raman spectroscopy techniques and technology can be effectively applied for environmental water analysis. Usually, normal Raman spectra of environmental waters, such as seawater, salt lakes waters show a weak-medium sulfate signal at about 981 cm-1 along with the stretching and bending modes of water. Rarely, weak bands attributable to dissolved CO2 and HCO3- are visible with weak intensity. We compared NIR-Raman and Raman spectra with visible laser excitation at 532 nm, which is resonant for carotenoids-containing microorganisms from water in bulk liquid or drop coating deposition samples, in multiple water samples from different spatial and temporal locations to include seawaters from Adriatic Sea (oligotrophic), Black Sea (eutrophic) and salt lakes waters (Cojocna Lakes (Lake1 and Lake2), Ursu Lake, Dead Sea). Valuable information can be obtained by combining resonance Raman spectroscopy using a Renishaw InVia Raman system coupled with a Leica research-grade microscope with a 532 nm laser with information from the FT-Raman spectra of the same waters. When photosynthetic microorganisms are abundant, in non-resonance conditions, a weak band of carotenoids is visible in FT-Raman or NIR-Raman spectra, suggesting photosynthetic microorganisms abundance. Such bulk waters show a high fluorescence background that sometimes covers any band, or reveal resonantly-enhance carotenoid bands arising from microorganisms under 532 nm excitation when Raman spectra of bulk liquid are tried. Drop coating deposition Raman (DCDR) technique could be more effectiv in rapidly assessing water droplet content under confocal micro-Raman spectroscopy. Both FT-Raman and microscopy techniques always record the sulfate ν1 (SO42-) Raman band at ~981 cm- 1 and water bands, δ(OH) at ~1637 cm-1 and ν(OH) Raman band at ~3218 cm-1 as shown in several comparative examples. Relative intensity ratio of ~981 cm- 1 and ~1637 cm-1 is proportional to sulfate concentration and can be used for quantitative sulfate analysis, based on an adequate calibration curve of sulfate solutions. Two sample tests for variance (F-test) revealed significant differences between relative intensity ratio between the Black Sea and Adriatic Sea samples when p<0.05. SO42- concentration variation is accompanied by other ion concentration variations and, thus, linked with salinity, conductivity and pH, which are related to climate events, and also influence the distribution of aquatic organisms. Thus, combined Raman spectroscopy techniques and technology for environmental water measurements can provide fast and useful information for monitoring programs and highlight large differences between oligotrophic and eutrophic seawaters or salt lakes and their spatial-temporal dynamic change