scholarly journals Rapido trawling in the northern Adriatic Sea: effects on benthic communities in an experimental area

2000 ◽  
Vol 57 (3) ◽  
pp. 517-524 ◽  
Author(s):  
F Pranovi
Keyword(s):  
Adriatic Sea ◽  
Benthic Communities ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Experimental Area

Micro- and macrofaunal responses to major environmental changes in Holocene highstand sediments from the Northern Adriatic Sea

2021 ◽  
Author(s):  
Michaela Berensmeier ◽  
Adam Tomašových ◽  
Martin Zuschin
Keyword(s):  
Heavy Metal ◽  
Metal Pollution ◽  
Adriatic Sea ◽  
Environmental Changes ◽  
Benthic Communities ◽  
Time Averaging ◽  
Surface Mixed Layer ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Ecological Changes

<p>Benthic communities in the Northern Adriatic Sea experienced major environmental and ecological changes during the late Holocene, particularly in the late 20<sup>th</sup> century due to anthropogenic induced stressors such as hypoxic events. These events lead to mass mortalities and changes in benthic communities. Here, we assess stratigraphic changes in bulk sediment geochemistry and sedimentological attributes to quantify the magnitude and timing of environmental changes and to correlate them to ecological changes. We focus on the reconstruction of the micro- to macrobenthic community composition (foraminifera, ostracods, bivalves and gastropods) prior and after major anthropogenic impacts. We investigate the differences in responses of these taxonomic groups to environmental changes and account for the impact of time-averaging.</p><p>The 3-m-long gravity core was collected at 31 m water depth, off the Po prodelta in the western part of the northern Adriatic Sea. The upper 60 cm of the core represent a condensed record determined by sediment bypassing and winnowing during the early and late sea level highstand. In total, 50 shells of the common bivalve <em>Corbula gibba</em> were dated by <sup>14</sup>C-calibrated amino acid racemization (AAR) from the upper 30 cm and plant remains were dated by <sup>14</sup>C from deeper parts. These analyses show that median shell ages of <em>Corbula</em> decline downcore, from ~50 years in the top 2.5 cm to 1,400 years in the 5-7.5 cm increment, 2,900 years in the 10-12.5 cm increment, and 4,500 years in the 17.5-20 cm increment. Median age in the 28-33 cm increment is again 3,600 years, indicating effects of mixing. The youngest shell corresponds to 24 years BP in the top 2.5 cm and the oldest shell to to 7800 years BP at the base at 30 cm.  The 60 cm-long highstand record can be divided in 4 major intervals:</p><p>(1) Early-highstand sediments cover the development of a baseline community. Total abundances of micro-and macrobenthic species increase upwards (2) In the late-highstand sediments (around 12.5-15 cm), micro-and macrobenthic absolute species abundance are highest. Increase in eutrophication and heavy metal pollution is indicated by rising N levels and Pb content in bulk sediments. (3) At 5 cm depth, a major anthropogenic environmental shift indicated by strong pollution (Pb and Hg) and eutrophication (TOC) coincides with a strong decline in micro-and macrobenthic abundance and diversity (4) The surface-mixed layer yields a slight increase in micro-to macrobenthic abundances, next to a slight decrease of heavy metal pollution and eutrophication.</p><p><sup>14</sup>C-calibrated AAR shell ages indicate a relatively limited, centennial time averaging (measured by interquartile age ranges) of <em>Corbula</em> in the uppermost increment but then show a millennial-scale time-averaging below the uppermost surface-mixed layer. This can be linked to a decrease in bioturbation in the 20<sup>th</sup> century and to a slight increase in sedimentation rate. Although the record is affected by time-averaging, the micro-and macrobenthic community abundances show a distinct pattern that can be related to environmental changes from geochemical sediment proxies. Benthic foraminifers, ostracods and mollusks abundance show similar responses to sedimentological and geochemical tracers in these condensed sediments.</p>

scholarly journals Diversity and Distribution Patterns of Hard Bottom Polychaete Assemblages in the North Adriatic Sea (Mediterranean)

Diversity ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 408
Author(s):  
Barbara Mikac ◽  
Margherita Licciano ◽  
Andrej Jaklin ◽  
Ljiljana Iveša ◽  
Adriana Giangrande ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Benthic Communities ◽  
Structural Similarity ◽  
Distribution Patterns ◽  
Northern Adriatic Sea ◽  
Environmental Pressures ◽  
Northern Adriatic ◽  
The North ◽  
The Family ◽  
Abundance And Diversity

The knowledge on the hard bottom polychaete assemblages in the Northern Adriatic Sea, a Mediterranean region strongly affected by environmental pressures, is scarce and outdated. The objective of this paper was to update the information on polychaete diversity and depict their patterns of natural spatial variation, in relation to changes in algal coverage at increasing depth. Hard bottom benthos was quantitatively sampled by scraping off the substrate from three stations at Sveti Ivan Island (North Adriatic) at three depths (1.5 m, 5 m and 25 m). Polychaete fauna comprised 107 taxa (the majority of them identified at species level) belonging to 22 families, with the family Syllidae ranking first in terms of number of species, followed by Sabellidae, Nereididae, Eunicidae and Serpulidae. Considering the number of polychaete species and their identity, the present data differed considerably from previous studies carried out in the area. Two alien species, Lepidonotus tenuisetosus, which represented a new record for the Adriatic Sea, and Nereis persica, were recorded. The highest mean abundance, species diversity and internal structural similarity of polychaete assemblages were found at 5 m depth, characterised by complex and heterogeneous algal habitat. The DISTLM forward analysis revealed that the distribution of several algal taxa as well as some algal functional-morphological groups significantly explained the observed distribution patterns of abundance and diversity of polychaete assemblages. The diversity of the North Adriatic hard bottom polychaete fauna is largely underestimated and needs regular updating in order to detect and monitor changes of benthic communities in the area.

scholarly journals Molluscan benthic communities at Brijuni Islands (northern Adriatic Sea) shaped by Holocene sea-level rise and recent human eutrophication and pollution

The Holocene ◽  
2018 ◽  
Vol 28 (11) ◽  
pp. 1801-1817 ◽  
Author(s):  
Sara-Maria Schnedl ◽  
Alexandra Haselmair ◽  
Ivo Gallmetzer ◽  
Anna-Katharina Mautner ◽  
Adam Tomašových ◽  
...  
Keyword(s):  
Sea Level ◽  
Adriatic Sea ◽  
Environmental Changes ◽  
Anthropogenic Impacts ◽  
Benthic Communities ◽  
Marine Species ◽  
Benthic Assemblages ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
The Impact

The effects of and the interplay between natural and anthropogenic influences on the composition of benthic communities over long time spans are poorly understood. Based on a 160-cm-long sediment core collected at 44 m water depth in the NE Adriatic Sea (Brijuni Islands, Croatia), we document changes in molluscan communities since the Holocene transgression ~11,000 years ago and assess how they were shaped by environmental changes. We find that (1) a transgressive lag deposit with a mixture of terrestrial and marine species contains abundant seagrass-associated gastropods and epifaunal suspension-feeding bivalves, (2) the maximum-flooding phase captures the establishment of epifaunal bivalve-dominated biostromes in the photic zone, and (3) the highstand phase is characterized by increasing infaunal suspension feeders and declining seagrass-dwellers in bryozoan-molluscan muddy sands. Changes in the community composition between the transgressive and the highstand phase can be explained by rising sea level, reduced light penetration, and increase in turbidity, as documented by the gradual up-core shift from coarse molluscan skeletal gravel with seagrass-associated molluscs to bryozoan sandy muds. In the uppermost 20 cm (median age <200 years), however, epifaunal and grazing species decline and deposit-feeding and chemosymbiotic species increase in abundance. These changes concur with rising concentrations of nitrogen and organic pollutants due to the impact of eutrophication, pollution, and trawling in the 20th century. The late highstand benthic assemblages with abundant bryozoans, high molluscan diversity, and abundance of soft-bottom epi- and infaunal filter feeders and herbivores represent the circalittoral baseline community largely unaffected by anthropogenic impacts.

scholarly journals Response to oxygen deficiency (depletion): Bivalve assemblages as an indicator of ecosystem instability in the northern Adriatic Sea

Biologia ◽  
2011 ◽  
Vol 66 (6) ◽  
Author(s):  
Vedrana Nerlović ◽  
Alper Doğan ◽  
Mirjana Hrs-Brenko
Keyword(s):  
Adriatic Sea ◽  
Oxygen Deficiency ◽  
Benthic Communities ◽  
Marine Ecosystem ◽  
Anthropogenic Disturbances ◽  
Ecosystem Stability ◽  
Ecological Quality ◽  
Northern Adriatic Sea ◽  
Northern Adriatic

AbstractBenthic communities represent a powerful tool for the detection of natural and anthropogenic disturbances, as well as for the assessment of marine ecosystem stability. This paper shows that bivalve assemblages could serve as excellent indicators of disturbance and ecosystem instability. The goal of this study was to compare two sets of data in order to determine the differences between two different periods belonging to bivalve assemblage in the muddy detritic bottom of the northern Adriatic Sea in the post-anoxic period during December 1989, 1990, 1991 and quite a while later, during 2003, 2004 and 2005. Abundances of some indicator species such as Corbula gibba, Modiolarca subpicta and Timoclea ovata were detected during the post-anoxic period. Recruitment in the quality of bivalve assemblages was proved by the ecologic and biotic indexes during 2003, 2004 and 2005, during a period of relatively stable ecological conditions. Fluctuation in bivalve diversity due to the ecological quality of the marine ecosystem in the eastern part of the northern Adriatic Sea is also discussed.

Basin-wide homogenization of soft-bottom benthic communities in the wake of anthropogenic habitat degradation in the northern Adriatic Sea

2020 ◽  
Author(s):  
Martin Zuschin ◽  
Alexandra Haselmair ◽  
Ivo Gallmetzer ◽  
Anna Wieser ◽  
Adam Tomasovych
Keyword(s):  
Sea Level ◽  
Adriatic Sea ◽  
Human Impacts ◽  
Benthic Communities ◽  
Sediment Cores ◽  
Time Averaging ◽  
Sedimentation Rates ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Anthropogenic Habitat

&lt;p&gt;We studied the origin and collapse of Holocene benthic baseline communities in the northern Adriatic Sea from sediment cores and surface grab samples at eight widely spaced sites. They cover areas with sedimentation rates spanning two orders of magnitude, with different nutrient input and with different degrees of time-averaging, ranging from decadal to millennial temporal resolution. Data from sediment cores indicate that during the transgressive phase and maximum flooding, sea-level and establishment of the modern circulation pattern determined the development of benthic communities in shallow-water, vegetated habitats with epifaunal biostromes and, in deeper waters, with bryozoan meadows. After sea-level stabilization, the composition of these baseline communities remained relatively uniform and started to change markedly only with the intensification of human impacts in the late highstand, leading to a dominance of infauna and a decline of epifauna at all sites. This profound ecological change reduced species richness, increased the abundance of infaunal suspension feeders, and led to a decline of grazers and deposit feeders. Live-dead data from grab samples give deeper insight into the degree of anthropogenic impact in historical times. At all sites the living assemblages differ strongly from the death assemblages. At some sites from oligotrophic settings with low sedimentation rates, a total overturn in the community composition is obvious: formerly abundant species have disappeared completely, while the living assemblage is numerically dominated by species that were not present before. Even at sites, which are characterized by physically stressful conditions (i.e., high sedimentation rates in the Po delta), some species that were abundant in the death assemblage have totally disappeared from the living assemblage. Comparison with the dataset from sediment cores documents the recent establishment of an impoverished community, which has no analogue in the Holocene history of the northern Adriatic Sea.&lt;/p&gt;

scholarly journals Spatial distribution of microphytobenthos, meiofauna and macrofauna in the north-western Adriatic Sea: a synoptic study

2015 ◽  
Vol 6 (1/2) ◽  
Author(s):  
Annalisa Franzo ◽  
Tamara Cibic ◽  
Paola Del Negro ◽  
Cinzia De Vittor
Keyword(s):  
Adriatic Sea ◽  
Multiple Stressors ◽  
Inorganic Nitrogen ◽  
Benthic Communities ◽  
Nutrient Loads ◽  
Northern Adriatic Sea ◽  
Sediment Grain Size ◽  
Coastal System ◽  
Northern Adriatic ◽  
Station Grid

<p>In view of the general paucity of integrated information on offshore benthic communities in the Adriatic Sea and given the vulnerability of this particular coastal system, microphytobenthos, meiofauna and macrofauna were synoptically investigated in front of the Emilia-Romagna coast (northern Adriatic Sea) in September 2010 and March 2011. As required by the Marine Strategy Framework Directive, which extends its action beyond the territorial waters (within 12 nmi) of the Member States, our findings could help to fill the gap of knowledge on the environmental status in offshore areas since the study was carried out also at &gt;12 nmi from the coastline. In fact, sediment samples for the analysis of the benthic communities were collected from a 10-point-station grid that covered an area of about 400 km<sup>2</sup> with water depths ranging from 13 to 50 m. The variability of the sediment grain size and other chemical variables in the sediment suggests the presence of two distinct environmental contexts that enhance the proliferation of different benthic communities. At the inshore stations (depth &lt;20 m) the higher sand percentages and the maxima of dissolved inorganic nitrogen concentrations indicate the presence of hydrodynamic perturbations and the influence of nutrient loads of terrestrial origin. Inshore, both meio- and macrofaunal communities were poorly structured and dominated by relatively more opportunistic taxa, such as nematodes and the bivalve <em>Corbula gibba</em>. Offshore stations (depth &gt;20 m) had muddier sediments, which likely exerted a greater retention of sediment-bound organic matter. These conditions seemed to favour benthic deposit feeders like meio- and macrofaunal annelids. Surprisingly, a conspicuous microphytobenthic community, mainly represented by the diatom <em>Paralia sulcata, </em>has been observed even at remarkable depths (~50 m) opening new questions regarding the role of these organisms in dim-light conditions. Although the investigated benthic communities were, to some extent, moderately influenced by multiple stressors, the co-existence of sensitive taxa (such as meiofaunal copepods and the amphipod <em>Ampelisca </em>spp.) with opportunistic ones (<em>i.e</em>., <em>C. gibba</em>) suggests that the benthic domain in the investigated area is not severely impacted.</p>

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