Search results for "algae"

The duality of ocean acidification as a resource and a stressor

2018

Ecologically dominant species often define ecosystem states, but as human disturbances intensify, their subordinate counterparts increasingly displace them. We consider the duality of disturbance by examining how environmental drivers can simultaneously act as a stressor to dominant species and as a resource to subordinates. Using a model ecosystem, we demonstrate that CO2-driven interactions between species can account for such reversals in dominance; i.e., the displacement of dominants (kelp forests) by subordinates (turf algae). We established that CO2 enrichment had a direct positive effect on productivity of turfs, but a negligible effect on kelp. CO2 enrichment further suppressed the …

Altered epiphyte community and sea urchin diet in Posidonia oceanica meadows in the vicinity of volcanic CO2 vents

2017

Ocean acidification (OA) predicted for 2100 is expected to shift seagrass epiphyte communities towards the dominance of more tolerant non-calcifying taxa. However, little is known about the indirect effects of such changes on food provision to key seagrass consumers. We found that epiphyte communities of the seagrass Posidonia oceanica in two naturally acidified sites (i.e. north and south sides of a volcanic CO2 vent) and in a control site away from the vent at the Ischia Island (NW Mediterranean Sea) significantly differed in composition and abundance. Such differences involved a higher abundance of non-calcareous crustose brown algae and a decline of calcifying polychaetes in both acidif…

Influence of ambient temperature on the photosynthetic activity and phenolic content of the intertidal Cystoseira compressa along the Italian coastli…

2019

Understanding the physiological responses of intertidal seaweeds to environmental factors is fundamental to characterize their local physiological adaptation and success in the face of climate change. We measured the photosynthetic activity and the total phenolic content of the intertidal alga Cystoseira compressa and explored their relationship with latitude or local ambient air and seawater temperatures. Our results show that, when submerged, the photosynthetic activity of C. compressa showed values typical for non-stressed thalli, and the seawater temperatures found across sites explained the variability of these values. We observed a decrease in the photosynthetic activity of C. compres…

Food selection of a generalist herbivore exposed to native and alien seaweeds

2018

Understanding which factors influence the invasion of alien seaweed has become a central concern in ecology. Increasing evidence suggests that the feeding preferences of native herbivores influence the success of alien seaweeds in the new community. We investigated food selection of a generalist native grazer Paracentrotus lividus, in the presence of two alien seaweeds (Caulerpa cylindracea and Caulerpa taxifolia var. distichophylla) and two native seaweeds (Dictyopteris membranacea and Cystoseira compressa). Sea urchins were fed with six experimental food items: C. cylindracea, C. taxifolia var. distichophylla, a mixture of C. cylindracea and C. taxifolia var. distichophylla, D. membranace…

Ocean acidification can mediate biodiversity shifts by changing biogenic habitat

2016

The effects of ocean acidification (OA) on the structure and complexity of coastal marine biogenic habitat have been broadly overlooked. Here we explore how declining pH and carbonate saturation may affect the structural complexity of four major biogenic habitats. Our analyses predict that indirect effects driven by OA on habitat-forming organisms could lead to lower species diversity in coral reefs, mussel beds and some macroalgal habitats, but increases in seagrass and other macroalgal habitats. Available in situ data support the prediction of decreased biodiversity in coral reefs, but not the prediction of seagrass bed gains. Thus, OA-driven habitat loss may exacerbate the direct negativ…

Drawing the Line at Neglected Marine Ecosystems: Ecology of Vermetid Reefs in a Changing Ocean

2016

Vermetid mollusks form reefs that protect coasts from erosion, regulate sediment transport, serve as carbon sinks, and provide habitat for many fish and invertebrates. This biogenic habitat is found in tropical, sub-tropical, and warmtemperate coastal areas, such as Bermuda, oceanic islands in Brazil, and Hawaii, several locations within the Caribbean and the Mediterranean. These reefs are functionally similar to tropical coral fringing reefs but are built by gregarious vermetid gastropods cemented by a crustose coralline algal species, which probably triggers their settlement. Some descriptive studies in different regions worldwide and comparisons among tropical and Mediterranean reefs con…

Antioxidant response, induced by the invasive algae Caulerpa distichophylla and C. racemosa, in the sea urchin Paracentrotus lividus

2014

DO INVASIVE MACROALGAE INFLUENCE ASSOCIATED MOLLUSC DIVERSITY IN THE MEDITERRANEAN SEA ?

2013

The benthic molluscs associated to the non-indigenous red algae Asparagopsis taxiformis invading the Mediterranean rocky subtidal were compared with those associated to a native brown alga. The results showed a marked difference in species richness and abundance between native and non-native algal species.

Macroalgal forest vs sea urchin barren: Patterns of macro-zoobenthic diversity in a large-scale Mediterranean study: Macro-zoobenthos of barren and m…

2020

The study aimed at contributing to the knowledge of alternative stable states by evaluating the differences of mobile and sessile macro-zoobenthic assemblages between sea urchin barrens and macroalgal forests in coastal Mediterranean systems considering a large spatial scale. Six sites (100 s km apart) were selected: Croatia, Montenegro, Sicily (Italy), Sardinia (Italy), Tuscany (Italy), and Balearic Islands (Spain). A total of 531 taxa, 404 mobile and 127 sessile macro-invertebrates were recorded. Overall, 496 and 201 taxa were found in macroalgal forests and in barrens, respectively. The results of this large-scale descriptive study have met the expectation of lower macrofauna complexity …

Modeling Macroalgal Forest Distribution at Mediterranean Scale: Present Status, Drivers of Changes and Insights for Conservation and Management

2020

Macroalgal forests are one of the most productive and valuable marine ecosystems, but yet strongly exposed to fragmentation and loss. Detailed large-scale information on their distribution is largely lacking, hindering conservation initiatives. In this study, a systematic effort to combine spatial data on Cystoseira C. Agardh canopies (Fucales, Phaeophyta) was carried out to develop a Habitat Suitability Model (HSM) at Mediterranean scale, providing critical tools to improve site prioritization for their management, restoration and protection. A georeferenced database on the occurrence of 20 Cystoseira species was produced collecting all the available information from published and grey lit…