1,720,985 research outputs found
Mitigating the impacts of coastal defence measures
No full textDefense measures have a strong impact on species composition, abundance and diversity of coastal marine environments. Understanding the factors controlling these impacts is crucial for proper management of coastal areas. We show results of field studies aiming at developing means for promoting the growth of desirable species and for controlling the spread of invasive species on coastal man-made structures
Conservation and restoration of fragmented communities of canopy-forming macroalgae in ecosystems undergoing global climate change.
No full textLoss and recovery potential of marine habitats: an experimental study of factors maintaining resilience in subtidal algal forests at the Adriatic sea.
No full textBACKGROUND: Predicting and abating the loss of natural habitats present a huge challenge in science, conservation and management. Algal forests are globally threatened by loss and severe recruitment failure, but our understanding of resilience in these systems and its potential disruption by anthropogenic factors lags well behind other habitats. We tested hypotheses regarding triggers for decline and recovery potential in subtidal forests of canopy-forming algae of the genus Cystoseira. METHODOLOGY/PRINCIPAL FINDINGS: By using a combination of historical data, and quantitative in situ observations of natural recruitment patterns we suggest that recent declines of forests along the coasts of the north Adriatic Sea were triggered by increasing cumulative impacts of natural- and human-induced habitat instability along with several extreme storm events. Clearing and transplantation experiments subsequently demonstrated that at such advanced stages of ecosystem degradation, increased substratum stability would be essential but not sufficient to reverse the loss, and that for recovery to occur removal of the new dominant space occupiers (i.e., opportunistic species including turf algae and mussels) would be required. Lack of surrounding adult canopies did not seem to impair the potential for assisted recovery, suggesting that in these systems recovery could be actively enhanced even following severe depletions. CONCLUSIONS/SIGNIFICANCE: We demonstrate that sudden habitat loss can be facilitated by long term changes in the biotic and abiotic conditions in the system, that erode the ability of natural ecosystems to absorb and recover from multiple stressors of natural and human origin. Moreover, we demonstrate that the mere restoration of environmental conditions preceding a loss, if possible, may be insufficient for ecosystem restoration, and is scarcely cost-effective. We conclude that the loss of complex marine habitats in human-dominated landscapes could be mitigated with appropriate consideration and management of incremental habitat changes and of attributes facilitating system recovery
Managing coastal defence structures to mitigate their impacts and elevate their ecological value
No full textCorridors for aliens but not for natives: effects of marine urban sprawl at a regional scale
Get PDFAim: The global sprawl of marine hard infrastructure (e.g. breakwaters, sea walls and jetties) can extensively modify coastal seascapes, but the knowledge of such impacts remains limited to local scales. We examined the regional-scale effects of marine artificial habitats on the distribution and abundance of assemblages of ascidians, a key group of ecosystem engineer species in benthic fouling systems.Location: Five hundred kilometers of coastline in the North Adriatic Sea.Methods: We sampled a variety of natural reefs, marine infrastructures and marinas, and tested hypotheses about the role of habitat type and location in influencing the relative distribution and abundance of both native and non-indigenous species.Results: Assemblages differed significantly between natural and artificial habitats and among different types of artificial habitats. Non-indigenous species were 2–3 times more abundant on infrastructures built along sedimentary coastlines than on natural rocky reefs or infrastructures built close to rocky coastlines. Conversely, native species were twice as abundant on natural reefs than on nearby infrastructures and were scarce to virtually absent on infrastructures built along sedimentary coasts. The species composition of assemblages in artificial habitats was more similar to that of marinas than of natural reefs, independently of their location.Main conclusions: Our results show that marine infrastructures along sandy shores disproportionally favour non-indigenous over native hard bottom species, affecting their spread at regional scales. This is particularly concerning for coastal areas that have low natural densities of rocky reef habitats. We discuss design and management options to improve the quality as habitat of marine infrastructures and to favour their preferential use by native species over non-indigenous ones
Detrital enrichment from marine urban structures and its far-field effects on soft-bottom assemblages
No full textWe report the results of a field experiment aimed at identifying and quantifying possible changes in sedimentary environments and associated assemblages related to the unnatural addition of detritus produced by hard bottom species associated to man-made, urban structures along the coasts of the north Adriatic se
Detrital enrichment from marine urban structures and its far-field effects on soft-bottom assemblages
No full textWe report the results of a field experiment aimed at identifying and quantifying possible changes in sedimentary environments and associated assemblages related to the unnatural addition of detritus produced by hard bottom species associated to man-made, urban structures along the coasts of the north Adriatic se
Studio sperimentale dei fattori che influenzano il successo di trapianto di alghe habitat forming su strutture artificiali marine
No full textL'erosione costiera è un problema di grande attualità a livello mondiale spesso affrontato adottando soluzioni di tipo ingegneristico. Tuttavia, le strutture artificiali di difesa costiera (SDC) presentano diversi impatti ecologici come ad esempio la diffusione di specie opportunistiche ed invasive. Viene qui affrontata la tematica di come migliorare il valore ecologico dei substrati artificiali marini esaminando la fattibilità di controllare la crescita di specie desiderabili sulle SDC. Le specie oggetto di studio sono macroalghe del genere Cystoseira. Queste specie formano habitat a canopy di grande valore ecologico, e sono in forte regressione in tutto il Mediterraneo. Test pilota hanno suggerito un ruolo potenzialmente limitante dell’erbivoria nel determinare la sopravvivenza e la crescita di Cystoseira sulle SDC. In questo lavoro vengono presentati i risultati di esperimenti volti ad analizzare il potenziale impatto di organismi erbivori sulla crescita e la sopravvivenza di talli giovanili di C. barbata trapantati su alcune SDC. Gli erbivori sono stati esclusi tramite gabbie con maglie di diverse dimensioni (1mm; 1cm; 1 cm con fori 6x3 cm). Gli esperimenti sono stati replicati in diversi siti lungo la costa adriatica. Il pascolo ha influenzato significativamente la crescita di macroalghe trapiantate sulle SDC: i giovanili sono cresciuti nei trattamenti protetti da gabbie, mentre la sopravvivenza è stata quasi nulla ne trattamenti di controllo non protetti da gabbie. Le rsposte osservate sono state relativamente uniformi tra siti differenti quando sono state usate gabbie di maglia fine, mentre gli effetti delle gabbie con maglia grande erano più variabili tra siti.. Sono stati effettuati ulteriori test per valutare la possibilità di mitigare l’impatto degli erbivori utilizzando modalità di trapianto differenti, quali il trapianto di individui di diversa taglia (1,4 ± 0,2 cm; 4,7 ± 0,4 cm, media ± DS) o una base di trapianto più elevata (h<2cm;
Threatened canopy algae: an experimental investigation of factors affecting the successful transplantation on artificial marine infrastructures
No full textWe present the results of experimental work aimed at examining the feasibility of controlling the growth of desirable species on man-made coastal defense structures (CDS). We focused on important habitat forming macroalgae of the genus Cystoseira, threatened by loss in the Mediterranean sea. We analyzed the role of grazing in influencing the survival and growth of Cystoseira on CDS, as pilot tests suggested herbivory has a potentially limiting role. Grazers’ impact on growth and survival of juvenile thalli of C. barbata was assessed using cages of different mesh size. Consistency of grazing effects was tested among sites kilometers apart along the Adriatic coast. Grazing was an important factor affecting macroalgae transplanted on CDS: juveniles grew whenever protected by cages, otherwise they suffered massive mortality and height decrease. The trend was relatively consistent at different sites when using cages of small mesh size, while the effects of cages of larger mesh were more variable. We tried to mitigate grazing using different transplantation approaches: a larger juvenile size or a higher transplantation base increased the survival of transplants. Characterizing ecological factors in CDS environments improves our ability to use artificial marine infrastructures as a scaffold for the conservation of threatened species.
Supporting info
Coastal erosion is a problem of major concern all over the world for which hard engineering solutions are widely implemented. However, man-made coastal defense structures have several ecological impacts (e.g. the spread of opportunistic and invasive species). We promote the idea that habitats developed on marine infrastructures can be managed to obtain a different colonization pattern. In particular, marine infrastructures can be used as a scaffold for the conservation of species of higher ecological value, often threatened in their natural habitats. In this perspective, it is vital to understand ecological factors ruling interactions between species on artificial structures
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