Colonization patterns of the date mussel Lithophaga lithophaga (L., 1758) on limestone breakwater boulders of a marina

Background and Purpose: The European date mussel (Lithophaga lithophaga) is widespread along the whole Mediterranean rocky coastline where it is frequently but illegally harvested. It is well known that the growth of the date mussel is very slow; however, patterns of recolonization of exploited surfaces have been scarcely investigated. The objective of this study is to assess colonization patterns of the date mussel on limestone boulders which have been in the sea for 19 years. These results could be useful in predicting the reconstitution of natural populations of the date mussel after harvesting. Materials and Methods: Limestone breakwater boulders were placed along the dike of the Marina of Rovinj (northern Adriatic, Istrian peninsula, Croatia) in 1984. Sampling was carried out in summer 2003 by SCUBA diving from six habitats of different inclination and topography: horizontal, inclined, vertical, sheltered, vaults, and whole stones. The abundance and biomass of L. lithophaga at the Marina were compared with those in natural control locations. Results: At the Marina, no date mussels were found on the horizontal and inclined sides of the boulders, and very few date mussels were found on the vertical side. On the contrary, sheltered and vault sides of boulders and whole stones were intensively colonized by L. lithophaga. In vaults, the abundance was similar to that in nature. In these habitats, L. lithophaga biomasswas generally lower than in nature. However, large date mussels, of lengths from 50 to 70 mm, were already present on boulders of theMarina. They amounted to 35% in the sheltered habitat, 24% in vaults, and 3% of the total number in whole stones. Conclusions: An unexpected high colonization rate and growth of date mussels was detected in certain unexposed rocky habitats at the boulders of the Marina. However, on the natural rocky Istrian coast, the date mussel was mostly collected on exposed inclined and vertical rocky surfaces where repopulation after harvesting may require very long periods

Plant Diversity of Gornji Kamenjak (Istria, Croatia)

The vascular flora of Significant Landscape Gornji Kamenjak in Istria was investigated in different vegetation periods from 2012 to 2013, and a total of 507 plant taxa (468 species and 39 subspecies) were recorded. Part of them werw previously registered, while some are recorded for the first time. The studied area was poorly investigated in the past, therefore there was a need for this study, representing a very detailed floristic survey of the area. The most dominant families were grasses (Poaceae, 11.8%), legumes (Fabaceae, 10.6%), daisies (Asteraceae, 6.5%) and mints (Lamiaceae, 5.5%). The domination of therophytes (37.0%) indicates that the climate of Gornji Kamenjak shows a high influence of the Mediterranean climate, followed by hemicryptophytes (30.8%) and geophytes (12.6%). We recorded a total of 11 invasive species across the whole investigated area, as well as the occurrence of 15 endangered and 13 endemic plant taxa. The results of our research of autochthonous vascular flora indicate high richness and diversity of plant species in the studied area

Preliminarno istraživanje raznolikosti bezkralježnjaka unutar naselja alge Corallina officinalis na području južne Istre

Red coralligenous algae Corallina officinalis provides shelter to many invertebrate species from wave actions, predation and desiccation stress in the intertidal area. Physical structure and complexity of the habitat have a major influence on biodiversity of this community. The aim of this preliminary study was to examine the diversity of invertebrate assemblages inside the red algae C. officinalis turf. Three sampling locations were chosen where algal cover range was above 90%. On each location sampling was done quantitatively by scraping off within 3 replicate quadrats 20 x 20 cm in size. A total of 30,518 specimens were isolated from all sampling locations. The prevalent groups were amphipod crustaceans, polychaetes, bivalves and gastropods that made a total of 86% of all macrofaunal groups associated with algal turfs. The most abundant group were amphipods that made 42% of the total separated individual invertebrates. Our study demonstrated that C. offic-inalis is a very important habitat with high abundance and diversity of invertebrate assemblages.Crvena inkrustirajuća alga Corallina officinalis pruža zaklon mnogim beskralješnjacima u području mediolitorala od djelovanja valova, predacije i isušivanja. Karakteristična struktura i složenost staništa imaju veliki utjecaj na bioraznolikost ove zajednice. Cilj ovog rada bio je istražiti raznolikost faune beskralješnjaka unutar naselja crvene alge C. officinalis. Tri lokacije uzorkovanja odabrane su na području gdje je pokrivenost algom bila veća od 90%. Na svakoj lokaciji uzorko-vanje je provedeno kvantitativno u 3 replikata, struganjem unutar kvadrata veličine 20 x 20 cm. Ukupno je izolirano 30.518 jedinki, a dominantne skupine bile su amfipodni rakovi, mnogočetinaši, školjkaši i puževi. Ovi taksoni su činili ukupno 86% svih beskralješnjaka pronađenih unutar staništa alge. Naj-brojnija skupina su amfipodni rakovi koji su činili 42% ukupnih izoliranih beskralježnjaka. Naše je istraživanje pokazalo da je naselje alge C. officinalis vrlo važno stanište s visokom brojnošću i raznolikošću beskralješnjaka

The effects of an invasive seaweed on native communities vary along a gradient of land-based human impacts

The difficulty in teasing apart the effects of biological invasions from those of other anthropogenic perturbations has hampered our understanding of the mechanisms underpinning the global biodiversity crisis. The recent elaboration of global-scale maps of cumulative human impacts provides a unique opportunity to assess how the impact of invaders varies among areas exposed to different anthropogenic activities. A recent meta-analysis has shown that the effects of invasive seaweeds on native biota tend to be more negative in relatively pristine than in human-impacted environments. Here, we tested this hypothesis through the experimental removal of the invasive green seaweed, Caulerpa cylindracea, from rocky reefs across the Mediterranean Sea. More specifically, we assessed which out of land-based and sea-based cumulative impact scores was a better predictor of the direction and magnitude of the effects of this seaweed on extant and recovering native assemblages. Approximately 15 months after the start of the experiment, the removal of C. cylindracea from extant assemblages enhanced the cover of canopy-forming macroalgae at relatively pristine sites. This did not, however, result in major changes in total cover or species richness of native assemblages. Preventing C. cylindracea re-invasion of cleared plots at pristine sites promoted the recovery of canopyforming and encrusting macroalgae and hampered that of algal turfs, ultimately resulting in increased species richness. These effects weakened progressively with increasing levels of land-based human impacts and, indeed, shifted in sign at the upper end of the gradient investigated. Thus, at sites exposed to intense disturbance from land-based human activities, the removal of C. cylindracea fostered the cover of algal turfs and decreased that of encrusting algae, with no net effect on species richness. Our results suggests that competition from C. cylindracea is an important determinant of benthic assemblage diversity in pristine environments, but less so in species-poor assemblages found at sites exposed to intense disturbance from landbased human activities, where either adverse physical factors or lack of propagules may constrain the number of potential native colonizers. Implementing measures to reduce the establishment and spread of C. cylindracea in areas little impacted by land-based human activities should be considered a priority for preserving the biodiversity of Mediterranean shallow rocky reefs

Promjene sastava masnih kiselina u algi Fucus virsoides J. Agardh na različitim podlogama

The effect of the substratum type (natural, limestone, or artificial, concrete) on the fatty acid composition of Fucus virsoides in six habitats around the harbours and beaches of the Istrian coast (northern Adriatic Sea) was investigated during the summer, the period of maximum development. All habitats of F. virsoides were regulated by very similar environmental factors and were exposed to moderate anthropogenic influences. F. virsoides growing on artificial substrata was characterised by lower concentrations of fatty acids, lower proportions of fatty acids among total lipids, higher C16:0/18:1 ratios (FA: 6.7±0.6 mg g-1 d.w.; FA/TL: 22%; 16:0/18:1: 0.57±0.08) and an overall increase in saturation in comparison to communities growing on natural substrata (FA: 10.2±2.9–12.5±3.4 mg g-1 d.w.; FA/TL: 30.8–33.7%; 16:0/18:1: 0.34±0.11–0.45±0.13). These results likely reflect the less favourable conditions for F. virsoides development on artificial substrates relative to natural substrates. The physiological processes of the algae growing on artificial substrata were more impaired with increasing age (FA: 1.9±0.6 mg g-1d.w.; FA/TL: 18.2%; 16:0/18:1: 0.68±0.08).U proljeće tijekom maksimuma vegetacijskog razvoja smeđe alge Fucus virsoides istražen je učinak podloge (prirodna, vapnenac ili umjetna, beton) na sastav masnih kiselina u algi. Uzorkovano je na šest staništa, uključujući luke i plaže, duž istarske obale (sjeverni Jadran). Sva staništa su bila pod utjecajem vrlo sličnih okolišnih čimbenika, i izložena umjerenom antropogenom utjecaju. Za vrstu F. virsoides na umjetnoj podlozi karakteristična je niža koncentracija masnih kiselina (MK), njihov niži udio u ukupnim lipidima (UL), povišeni C16:0/18:1 omjeri (MK: 6.7±0.6 mg g -1 s.t.; MK/UL: 22%; 16:0/18:1: 0.57±0.08) te veća zasićenost u usporedbi sa zajednicama na prirodnoj podlozi (MK: 10.2±2.9–12.5±3.4 mg g-1s.t.; MK/UL: 30.8–33.7%; 16:0/18:1: 0.34±0.11–0.45±0.13). Dobiveni rezultati odražavaju nepovoljne uvjete za rast i razvoj vrste F. virsoidesna umjetnoj podlozi u odnosu na prirodnu. Na umjetnoj podlozi je utvrđeno lošije fiziološko stanje u starijim primjercima alge (MK: 1.9±0.6 mg g-1 s.t.; MK/UL: 18.2%; 16:0/18:1: 0.68±0.08)

UTJECAJ NADOPUNE PREHRANE S Lactiplantibacillus plantarum I NA ČEŠLJAČU Aequipecten opercularis POD SIMULIRANO PROMJENJENIM KLIMATKSIM UVJETIMA

This study examined the effects of dietary supplementation of queen scallop Aequipecten opercularis with an indigenous strain of lactic acid bacteria (LAB), such as Lactiplantibacillus plantarum I previously isolated from its digestive tract, on gut microbial populations and growth rates during cultivation under simulated climate change conditions (pH 7.8, T=16±2°C). After one month of feeding, the results showed a noticeable reduction in aquaculture diseases causing pathogens while maintaining sufficient viable L. plantarum I cells. A higher pH and temperature resulted in higher growth rates, measured by the weight and length of scallops, compared to the control group. The results obtained shed light on the influence of the addition of lactic acid bacteria on the growth of bivalve mollusks under normal and climate change conditions, and provide control of pathogenic microorganisms. In the context of climate change, host-pathogen interactions need to be recognized and put under control by applying natural solutions to minimize the environmental footprint.U ovoj studiji ispitani su učinci dodataka prehrani češljači Aequipecten opercularis s autohtonim sojem bakterija mliječne kiseline (LAB), kao što je Lactiplantibacillus plantarum I koji je prethodno izoliran iz njegovog probavnog trakta, na populacije crijevnih mikroba i stope rasta tijekom uzgoja pod simulirano promjenjenim klimatskim uvjetima (pH 7,8, T=16±2°C). Nakon mjesec dana hranjenja, rezultati su pokazali zamjetno smanjenje uzročnika bolesti u akvakulturi uz zadržavanje dovoljne količine živih stanica L. plantarum I. Viši pH i temperatura rezultirali su većim stopama rasta, izmjerenom težinom i duljinom školjkaša, u usporedbi s kontrolnom skupinom. Dobiveni rezultati rasvjetljavaju utjecaj dodatka bakterija mliječne kiseline na rast školjkaša u normalnim i klimatskim promijenjenim uvjetima te omogućuju suzbijanje patogenih mikroorganizama. U kontekstu klimatskih promjena, interakcije domaćin-patogen treba prepoznati i staviti pod kontrolu primjenom prirodnih rješenja kako bi se smanjio utjecaj na okoliš