Lena Granhag

Interactions between wave action and grazing control the distribution of intertidal macroalgae

Canopy-forming macroalgae are key species on temperate rocky shores. However, there is a lack of understanding of how the relative balance of physical and biological factors controls the establishment and persistence of intertidal macroalgae. Here we present an integrated study of the relative importance of wave-induced forces and grazing for the recruitment and survival of the canopy-forming intertidal macroalgae Fucus vesiculosus and F. spiralis. A set of overtopped breakwaters provided a nearly unconfounded gradient in wave exposure between seaward and landward sides. A biomechanical analysis was performed based on empirical measurements of maximum drag forces in breaking waves, a model of long-term maximum wave height, and the breaking stress of Fucus spp. The estimated maximum flow speed (7-8 m/s) on the seaward side of the breakwaters was predicted to completely dislodge or prune Fucus spp. larger than approximately 10 cm, while dislodgment was highly unlikely on the landward side for all sizes. Experimental transplantation of Fucus spp. supported the biomechanical analysis but also suggested that mechanical abrasion may further limit survival in wave-exposed locations. Experimental removal of the limpet Patella vulgata, which was the principal grazer at this site, resulted in recruitment of Fucus spp. on the seaward side. We present a model of limpet grazing that indicates that limpet densities >5-20 individuals/m2 provide a proximate mechanism preventing establishment of Fucus spp., whereas wave action >2 m/s reduces persistence through dislodgment and battering. In a conceptual model we further propose that recruitment and survival of juvenile Fucus spp. are controlled indirectly by wave exposure through higher limpet densities at exposed locations. This model predicts that climate change, and in particular an increased frequency of storm events in the northeast Atlantic, will restrict fucoids to more sheltered locations.

Stimulated bacterioplankton growth and selection for certain bacterial taxa in the vicinity of the ctenophore Mnemiopsis leidyi

Episodic blooms of voracious gelatinous zooplankton, such as the ctenophore Mnemiopsis leidyi, affect pools of inorganic nutrients and dissolved organic carbon by intensive grazing activities and mucus release. This will potentially influence bacterioplankton activity and community composition, at least at local scales; however, available studies on this are scarce. In the present study we examined effects of M. leidyi on bacterioplankton growth and composition in incubation experiments. Moreover, we examined community composition of bacteria associated with the surface and gut of M. leidyi. High release of ammonium and high bacterial growth was observed in the treatments with M. leidyi relative to controls. Deep 454 pyrosequencing of 16 S rRNA genes showed specific bacterial communities in treatments with M. leidyi as well as specific communities associated with M. leidyi tissue and gut. In particular, members of Flavobacteriaceae were associated with M. leidyi. Our study shows that M. leidyi influences bacterioplankton activity and community composition in the vicinity of the jellyfish. In particular during temporary aggregations of jellyfish, these local zones of high bacterial growth may contribute significantly to the spatial heterogeneity of bacterioplankton activity and community composition in the sea.

Instantaneous Flow Structures and Opportunities for Larval Settlement: Barnacle Larvae Swim to Settle.

Water flow affects settlement of marine larvae on several scales. At the smallest scale local flow regime may control the probability of adhesion to the substrate. Our aim was to mechanistically understand the transition from suspended to attached larvae in turbulent flow. Recently it was proposed that opportunities for larval settlement in turbulent boundary layers depend on time windows with suitable instantaneous flow properties. In flume flow we characterized the proportion of suitable time windows in a series of flow velocities with focus on the near-bed flow. The change in the proportion of potential settling windows with increasing free-stream velocities was compared to the proportion of temporary attachment of barnacle cypris larvae at different flow velocities. We found large instantaneous flow variations in the near-bed flow where cyprid attachment took place. The probability of temporary attachment in cyprids declined with local flow speed and this response was compatible with a settling window lasting at least 0.1 s with a maximum local flow speed of 1.9–2.4 cm s-1. Cyprids swam against the near-bed flow (negative rheotaxis) and the swimming speed (1.8 cm s-1) was close to the critical speed that permitted temporary attachment. We conclude that temporary attachment in barnacle cyprids requires upstream swimming to maintain a fixed position relative to the substrate for at least 0.1 s. This behaviour may explain the ability of barnacles to recruit to high-flow environments and give cyprids flexibility in the pre-settlement choice of substrates based on flow regime.

The nutrient load from food waste generated onboard ships in the Baltic Sea

The combination of the sensitive characteristics of the Baltic Sea and the intense maritime traffic makes the marine environment vulnerable to anthropogenic influences. The theoretical scenario calculated in this study shows that the annually generated food waste onboard ships in traffic in the Baltic Sea contains about 182tonnes of nitrogen and 34tonnes of phosphorus. Today, all food waste generated onboard can be legally discharged into the marine environment at a distance of 12NM from the nearest land. The annual load of nitrogen contained in the food waste corresponds to 52% of load of nitrogen from the ship-generated sewage. Future regulations for sewage discharge in the Baltic Sea will require significant reduction of total nitrogen and phosphorus released. The contribution of nutrients from food waste compared to sewage will therefore be relatively larger in the future, if food waste still can be legally discharged.

Effect of ship hull form on the resistance penalty from biofouling

Abstract Hull biofouling is a well-known problem for the shipping industry, leading to increased resistance and fuel consumption. Considering that the effects of hull form on resistance are known to be higher for a less slender hull, it is hypothesised in this paper that the effect of biofouling roughness on resistance is also dependent on the hull form. To test this hypothesis, previously reported full-scale numerical results on a containership are re-analysed. Form effects on roughness penalties, corresponding to KΔCT = 0.058 ± 0.025, are observed at a low speed (19 knots, Res = 2.29 × 109), which are however cancelled out by traditionally neglected roughness effects on wave-making resistance at a higher speed (24 knots, Res = 2.89 × 109). It is concluded that hull form effects on biofouling penalties can be significant at low speeds, though not generalisable for higher speeds, namely when wave-making resistance corresponds to ≥ 29% of total resistance.

The Natural Environment and Human Impacts

To comprehend the implications of the various environmental issues that man is inducing on the Earth (with a focus on the shipping industry), an understanding of the Earths major systems is necessary. The natural environment, which consists of air, water, land and living organisms, is a dynamic system in which material and energy are exchanged within and between the individual components. The system is divided into four spheres (atmosphere, hydrosphere, geosphere, and biosphere), and fluxes of energy and material are exchanged amongst these spheres. The spheres also largely govern the fate of various environmental problems originating from the shipping industry. Therefore, background information related to these spheres is provided, and their major properties and implications are explained. Regarding the atmosphere, radiation and energy budgets are explained in conjunction with the weather and climate. Concerning the hydrosphere, oceanography is introduced together with marine ecology. Addressing the geosphere, the elements in the Earths crust and mineral commodities are discussed. Regarding the biosphere, energy is transferred through food chains; the differences between life in water and life on land are examined. Energy flows through and is stored in these spheres; this stored energy is essential to the natural environment and human society. The different primary energy sources are described and divided into non-renewable and renewable sources. Finally, an introduction to human impacts on the natural environment and to major environmental issues is provided.

Phosphorus flows on ships: Case study from the Baltic Sea

Material flow analysis is used to identify and quantify the flow of phosphorus (P) in ship-generated food waste and wastewater. Passenger, cruise, RoPax and cargo ships in the Baltic Sea were investigated in three scenarios: (1) if all waste is discharged to sea, (2) if all waste is disposed of ashore or (3) if the food waste fraction is disposed of ashore and wastewater is treated on-board. About 107 tonnes of P is generated annually in the waste streams, with highest contribution of approximately 62 tonnes (58%) from wastewater in the ship-category RoPax. Approximately 24 tonnes of P is contained in the food waste generated by the ships in the study. Forthcoming regulations over allowed nutrient concentrations in sewage will lead to 80% reduction in P from passenger ships and can reduce about 31 tonnes of P entering the Baltic Sea environment. If both sewage and grey water instead are offloaded in port reception facilities, about 76 tonnes of P-reduction to the sea can be reached. As most phosphorus recovery practices currently only are available on land it is recommended to direct the waste streams to port reception facilities for further treatment ashore.

Pathways to reduction and efficient handling of food waste on passenger ships: from Baltic Sea perspective

Food waste generation has received increasing attention in recent years. In this paper, we investigate the availability of information regarding food waste management on-board ships and describe how this information is communicated by companies operating passenger ships in the Baltic Sea. Furthermore, we summarize the aspects that influence efficient management of waste and identify pathways for food waste reduction on-board ships. The main three findings from this study are: (I) the information on waste handling at companies’ websites was to a large extent lacking. Food waste was mentioned in 22% of investigated ferry ship operator cases and in 32% of cruise ship operator cases. (II) In the interviews with environmental managers from two passenger ship companies, various aspects of food waste handling on-board ships were identified, which could be further grouped into technical, economic, management, legal and social categories. We suggest that the aspects of waste handling presented in this paper can serve as a framework for detection of the challenges and possibilities for different actors including shipping companies, ports and waste management agents. (III) The pathways towards efficient food waste handling may differ for individual ships, as it depends on vessel age, type of equipment and route schedules. The effort should be put in separating food waste from the rest of waste streams as it enables a clearer picture of the waste produced, increases the handling alternatives and may provide technological and economic benefits. Transparency and communication between the waste handling actors is the key in finding tailor-made solutions for treatment of ship-generated waste.

Improving Environmental Performance in Shipping

This book addresses the environmental issues related to shipping and the natural environment, including descriptions of and proposed solutions to the issues. Currently, challenges exist that must be addressed if shipping is to become sustainable and fulfil the zero vision of no harmful emissions to the environment. In this chapter, we evaluate the steps that have been taken (if any) to limit the various environmental issues and discuss possible steps to be taken to improve environmental performance. Furthermore, future challenges must also be addressed, e.g., the current trend of increasing ship operations in the Arctic. In general, three factors could be addressed in order to reach environmentally sustainable shipping: regulations, technical solutions, and increased environmental awareness.

Discharges to the Sea

In this chapter, various environmental issues from the shipping industry which ends up in the oceans are described. Oil pollution, wastewater, antifouling paint, ballast water and litter are all described in detail. Various sources of oil pollution exist, ranging from large accidents to small continuous leakages from, e.g., propeller shaft bearings. The behaviour of oil when it enters the sea can differ, ultimately affecting the environment. Wastewater from ships is divided into sewage and grey water, and different regulations can affect their characteristics. Fouling on ship hulls affects the drag on the ship, which increases fuel consumption when maintaining a constant speed. The various antifouling paints used today to combat fouling are described herein, and a review of the environmental implications of using these paints is provided. Ballast water contains organisms that can become invasive if released into a new geographical area. Invasive species can entail costs on the order of millions of euros. Finally, litter is discussed in this chapter. Litter is deposited in the ocean via several sources and can affect organisms over long periods of time. Plastic causes the largest litter-related problem because it does not biodegrade; such material only becomes smaller, ultimately reaching a microplastic state. Henee, litter can affect organisms in different ways.