| 1. |
- Moschella, P. S., et al.
(författare)
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Low-crested coastal defence structures as artificial habitats for marine life: Using ecological criteria in design
- 2005
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Ingår i: Coastal Engineering. - : Elsevier BV. - 0378-3839. ; 52:10-11, s. 1053-1071
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Tidskriftsartikel (refereegranskat)abstract
- Coastal defence structures to protect sedimentary coastlines from erosion and flooding are increasingly common throughout Europe. They will become more widespread over the next 10-30 years in response to rising and stormier seas and accelerating economic development of the coastal zone. Building coastal defences results in the loss and fragmentation of sedimentary habitats and their replacement by artificial rocky habitats that become colonised by algae and marine animals. The engineering design and construction of these structures have received considerable attention. However, the ecological consequences of coastal defences have been less extensively investigated. Furthermore, due to their rapid proliferation, there is a growing need to understand the role of these man-made habitats in the coastal ecosystems in order to implement impact minimisation and/or mitigation measures. As part of the DELOS project, targeted studies were carried out throughout Europe to assess the ecological similarity of low-crested coastal defence structures (LCS) to natural rocky shores and to investigate the influence of LCS design features on the colonising marine epibiota. LCSs can be considered as a relatively poor surrogate of natural rocky shores. Epibiotic communities were qualitatively similar to those on natural rocky shores as both habitats are regulated by the same physical and biological factors. However, there were quantitative differences in the diversity and abundance of epibiota on artificial structures. Typically, epibiotic assemblages were less diverse than rocky shore communities. Also, LCSs offered less structurally complex habitats for colonisation and in some locations experienced higher disturbance than natural shores. We propose several criteria that can be integrated into the design and construction of LCSs to minimise ecological impacts and allow targeted management of diversity and natural living resources. (c) 2005 Elsevier B.V. All rights reserved.
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| 2. |
- Airoldi, L., et al.
(författare)
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An ecological perspective on the deployment and design of low-crested and other hard coastal defence structures
- 2005
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Ingår i: Coastal Engineering. - : Elsevier BV. - 0378-3839. ; 52:10-11, s. 1073-1087
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Tidskriftsartikel (refereegranskat)abstract
- Coastal areas play a crucial role in the economical, social and political development of most countries; they support diverse and productive coastal ecosystems that provide valuable goods and services. Globally flooding and coastal erosion represent serious threats along many coastlines, and will become more serious as a consequence of human-induced changes and accelerated sea-level rise. Over the past century, hard coastal defence structures have become ubiquitous features of coastal landscapes as a response to these threats. The proliferation of defence works can affect over half of the shoreline in some regions and results in dramatic changes to the coastal environment. Surprisingly little attention has been paid to the ecological consequences of coastal defence. Results from the DELOS (Environmental Design of Low Crested Coastal Defence Structures, EVK3-CT-2000-00041) project indicate that the construction of coastal defence structures will affect coastal ecosystems. The consequences can be seen on a local scale, as disruption of surrounding soft-bottom environments and introduction of new artificial hard-bottom habitats, with consequent changes to the native assemblages of the areas. Proliferation of coastal defence structures can also have critical impacts on regional species diversity, removing isolating barriers, favouring the spread of non-native species and increasing habitat heterogeneity. Knowledge of the environmental context in which coastal defence structures are placed is fundamental to an effective management of these structures as, while there are some general consequences of such construction, many effects are site specific. Advice is provided to meet specific management goals, which include mitigating specific impacts on the environment, such as minimising changes to surrounding sediments, spread of exotic species or growth of nuisance species, and/or enhancing specific natural resources, for example enhancing fish recruitment or promoting diverse assemblages for eco-tourism. The DELOS project points out that the downstream effects of defence structures on coastal processes and regional-scale impacts on biodiversity necessitate planning and management at a regional (large coastline) scale. To effectively understand and manage coastal defences, environmental management goals must be clearly stated and incorporated into the planning, construction, and monitoring stages. (c) 2005 Elsevier B.V. All rights reserved.
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| 3. |
- Cardinale, Massimiliano, et al.
(författare)
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A centurial development of the North Sea fish megafauna as reflected by the historical Swedish longlining fisheries
- 2015
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 16:3, s. 522-533
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Tidskriftsartikel (refereegranskat)abstract
- Historically, to compensate for declining catches, fishers have usually shifted from species characterized by high catch rate onto less easily caught species or have moved into new fishing grounds. Such shifts are poorly documented for areas with a long history of exploitation (i.e. North Sea) as they occurred long time before the start of the regular assessments of the marine resources. The Swedish longline fisheries in the Kattegat-Skagerrak and North Sea have a long history that spans over several centuries. These fisheries have historically targeted large demersal predator fish as ling (Molva molva), cod (Gadus morhua), Atlantic halibut (Hippoglossus hippoglossus) and skates (mainly Dipturus spp.). In this study, data from the Swedish longline fisheries from 1859 to 1960 have been collated. The data show that the geographical expansion of the fishery was extensive. At the turn of the 20th century, offshore longlining became concentrated north and west of the Shetlands and Hebrides, and after the WWII, the fishery expanded to Iceland and Rockall. In the offshore fishery, CPUE for the main target species, ling, remained stable, whereas for the other species, with the exception of tusk (Brosme brosme), CPUE showed a dramatic decline over time. In contrast, in the coastal longlining fishery, severe declines were revealed for all major target species except cod. We argue that the constant search for new fishing grounds in the Northeast Atlantic reflects a dwindling resource, where the fishermen kept the catch rates of ling high by travelling to more and more distant fishing grounds. © 2014 John Wiley & Sons Ltd.
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| 4. |
- Hanson, Niklas, 1976, et al.
(författare)
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Population-level effects of male-biased broods in eelpout (Zoarces viviparus)
- 2005
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Ingår i: Environmental Toxicology and Chemistry. ; 24:5, s. 1235-1241
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Tidskriftsartikel (refereegranskat)abstract
- Effects of environmental pollutants are most obvious when mortality is increased. However, there are other nonlethal factors that may affect population size significantly. Endocrine disruption as a mechanism of action for pollutants recently has received much attention. Observations of effects likely caused by endocrine disruptors in pulp mill effluents have been made on several fish species, e.g., male-biased broods in eelpout (Zoarces viviparus). Fewer females represent a lower fecundity and could have dramatic effects on the population. In this study, a population viability analysis of the effects of skewed primary sex ratios in the eelpout was conducted using a female-based matrix population model. The model is age-structured with one deterministic version and another that incorporates environmental stochasticity. The model showed that the deterministic and stochastic growth rates in an undisturbed population (50{percnt} female fry) were 1.172 and 1.075, respectively, compared to 1.097 and 1.007 using the lowest proportion of female fry observed (38.7{percnt}). When primary sex ratios were more male-biased, the probability of pseudoextinction increased. Model simulations showed that the probability of a decreased population size to 5{percnt} of the initial within a 100-year time horizon was 44.7{percnt} with 38.7{percnt} female fry compared to only 7.7{percnt} for an undisturbed population.
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| 5. |
- Sundelöf, Andreas, 1974, et al.
(författare)
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Birth functions in stage structured two-sex models
- 2006
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Ingår i: ECOLOGICAL MODELLING. - : Elsevier BV. - 0304-3800. ; 193:3-4, s. 787-795
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Tidskriftsartikel (refereegranskat)abstract
- The most commonly used birth function in two-sex demographic models is the harmonic mean birth function. This function treats all individuals of one sex as identical, i.e., stage specific fecundity is not taken into account. In the analysis presented here, the harmonic mean birth function is developed to incorporate size and sex specific fecundities. This structured birth function is compared with the harmonic mean birth function using both a hypothetical population and data for populations of the limpet Patella vulgata. A general expression to calculate the threshold value where the unstructured and the structured birth functions coincide is also provided. Using the structured birth function resulted in changes in population dynamics, growth rate, proportion of males and reproductive output. In conclusion, the choice of birth function is important due to its effects on the deterministic population characteristics, which in turn may have consequences for the managements of endangered or vulnerable species.
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| 6. |
- Sundelöf, Andreas, 1974, et al.
(författare)
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Determinants of reproductive potential and population size in open populations of Patella vulgata
- 2010
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 157:4, s. 779-789
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Tidskriftsartikel (refereegranskat)abstract
- The importance of external and internal population processes in determining variation in reproductive output and variation in population size were quantified with model simulations for open populations of the sequentially hermaphroditic limpet Patella vulgata using field data from the Isle of Man and South West Ireland. Cross-correlation analyses of model outputs and elasticity analyses show that population dynamics are dominated by the effects of large females, and that recruitment adds little to reproductive output. However, populations experiencing low but highly variable recruitment appear male limited and recruitment pulses carrying young males into the population are correlated to reproductive output with a 2-5-year lag. We conclude that pulses in recruitment can be a major structuring force in these limpet populations, but site-specific post-recruitment processes will determine the relative importance of recruitment to population dynamics and the lag between recruitment and reproductive output.
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| 7. |
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| 8. |
- Sundelöf, Andreas, 1974
(författare)
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Larval dispersal and vertical migration behaviour - a simulation study for short dispersal times
- 2012
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Ingår i: Marine Ecology. - : Wiley. - 0173-9565 .- 1439-0485. ; 33, s. 183-193
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Tidskriftsartikel (refereegranskat)abstract
- Current speed often varies with depth, so vertical movements of larvae are expected to have profound effects on dispersal velocity and therefore dispersal potential. Systematic behaviours are expected to have strong effects on dispersal. However, reliable information on the presence of vertical migrations in larvae is scarce, but the few well investigated empirical examples justify a detailed simulation study and an analysis of potential effects. We present a spatially explicit 3D hydrodynamic model that incorporates biological information in the form of active particles advected in a Lagrangian fashion. The set-up is designed to analyze the sensitivity of dispersal distances to variation in vertical behaviour of larvae. We simulated short (4days) pelagic larval durations (PLDs) to determine whether behaviour might be important over short dispersal periods. We found that sinusoidal behaviours (slow vertical migration) in or out of phase with tides did not significantly change the dispersal patterns compared to those of larvae that remained at the surface. By contrast, a quadratic pattern of behaviour resulting in rapid vertical migration, in or out of phase with tides, had dramatic effects on both distance and direction of dispersal. The resulting dispersal kernels were found to be multimodal due to the interaction between tidal and meteorological components in flow. Incorporating biological information on larval migrations in Lagrangian simulation of dispersal will be important in estimates of connectivity and forecasting marine reserve networks. © 2011 Blackwell Verlag GmbH.
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| 9. |
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