24 January
Andrew Hirst, Queen Mary University of London: Changing size in a warming world?
The Temperature Size-Rule is near universal in ectotherms, and describes how, within-species, organisms mature at a smaller size when subjected to higher temperatures. The rule provides fundamental insights into physiological processes, and is a potential outcome of climate change. In this talk we develop a conceptual understanding of how organisms change size. This scheme shows the importance of the adult to progeny size ratio in metazoans, we examine this ratio using meta-analysis, and find that progeny size is much less temperature dependent than adult size. In effect size is 'reset' at birth. This leads us to the prediction that growth and development rates must have different temperature dependence in metazoans. We next test this rigourously using marine copepods as a rich source of data, and the outcome confirm our prediction. The wider implications of these findings are finally addressed. Importantly there are different mechanisms in how size changes are brought about in uni-cells (with divide by binary fission) and metazoans, and the work highlights important short comings in the assumptions of the Metabolic Theory of Ecology.
1 February
Jorn Bruggeman, Department of Earth Sciences/St. John's College, University of Oxford: Size-based phytoplankton: how complex communities can be captured with simple models
Phytoplankton control the aquatic ecosystems through their influence on biogeochemical cycling and higher trophic level productivity. The strength of this influence depends on the species composition of the phytoplankton communities, which varies profoundly in time and space. This suggests that to quantify the role of phytoplankton, we require detailed knowledge on hundreds of plankton species - knowledge that will remain beyond our reach for many years. Is there a way out? I propose that the combination of knowledge on the evolutionary history and present-day interspecific variation in phytoplankton, together with a modelling approach built upon physiological mechanisms and adaptation, provides a promising starting point. Much of the functional diversity in plankton is captured by variation in a small number of principal traits, e.g., species size. By representing key statistics of these traits, community models can acquire rich, adaptive behaviour without having to resolve large numbers of species. This approach is evaluated in a variety of settings, ranging from freshwater and marine water columns to the global ocean. This uncovers several characteristic similarities and differences between freshwater and marine systems, revolving around the relationships between species size and top-down and bottom-up control of phytoplankton populations.
9 February
Morten Limborg, DTU Aqua: Population structure and adaptation in the sea: insights from clupeid fishes
Long term sustainability of marine fish resources may be jeopardized from insufficient knowledge about intra-specific population structure and adaptive divergence. The large population sizes and high migration rates common to most marine fishes impede the differentiating effect of genetic drift. This has led to expectations of no population structure and that the occurrence of local adaptation should be rare in marine fishes.
Comprehensive genetic analyses on the small pelagic fish European sprat (Sprattus sprattus) revealed significant population structure throughout its distribution with an overall pattern of reduced connectivity across environmental transition zones. Population structure reflected both historical separations over glacial time scales and more recent colonisation of new habitats. Further, strong genetic divergence at several regional scales demonstrated limited connectivity among sea-going and local fjord populations along the Norwegian coast.
Advances in sequencing technologies now enable cost-effective developments of gene-associated markers facilitating detection of locally adapted populations. We developed hundreds of transcriptome derived markers to identify genes affected by natural selection in another small pelagic, the Atlantic herring (Clupea harengus). Comprehensive sampling throughout the northeastern Atlantic revealed clear genetic structure among regions. Furthermore, environmental analyses and strong signatures of divergent selection at a range of candidate genes suggested adaptation to local temperature and salinity conditions in herring populations.
Overall, results from this PhD revealed complex patterns of population structure and evidence for locally adapted populations in small pelagic fishes. These results contribute to our understanding of the evolutionary forces shaping biodiversity in the wild and findings may be extended from the actual species studied to assist managing fish resources under an evolutionarily sustainable framework.
16 February
Mohamed Adjou, University of Copenhagen: Modeling the influence from ocean transport, mixing and grazing on phytoplankton diversity
Phytoplankton diversity is known to be temporally and spatially heterogeneous throughout the global ocean. Since Hutchinson's “paradox of the plankton”, we have been trying to obtain a mechanistic understanding of what controls species coexistence and the community structure. I will present a simple model for analyzing the potential impact of transport by ocean currents and mixing, nutrient input into the euphotic zone and grazing pressure on phytoplankton diversity. Phytoplankton species are defined by their growth kinetics within 5 functional groups. Mortality is determined from selective grazing pressure and natural loss. The model sensitivity was analyzed in relation to changes in nutrient input and physical transports of biomasses and related to realistic values of new production and ocean currents, respectively. We show that phytoplankton diversity is sensitive to selective grazing. Model solutions imply that low nutrient inputs (oligotrophic conditions) are associated with relatively low diversity, and, correspondingly, relatively high nutrient inputs (mesotrophic-eutrophic conditions) are characterized by a relatively high diversity. The results of the model are in general accordance with observed patterns of global phytoplankton diversity. In a sensitivity study, we show that contributions of phytoplankton biomasses from relatively small physical transports by ocean currents or turbulent mixing increase diversity in the model significantly. These model results suggest a significant influence from ocean transports and mixing on phytoplankton diversity implying a higher diversity in dynamic areas.
1 March
Friederike Prowe, IFM GEOMAR & DTU Aqua: Zooplankton feeding formulations affect phytoplankton diversity and productivity in global ecosystem models
The potential of marine ecosystems to adapt to ongoing environmental change is largely unknown, making prediction of consequences for nutrient and carbon cycles particularly challenging. Realizing that biodiversity might influence the adaptation potential, recent global model approaches have identified bottom-up controls on patterns of phytoplankton diversity regulated by nutrient availability and seasonality. Top-down control of biodiversity by zooplankton feeding, however, has not been considered in depth in such models. Here we demonstrate how zooplankton predation with variable food preferences can enhance phytoplankton diversity in a self-assembling global ecosystem-circulation model. Simulated diversity increases more than three-fold with variable preferences relative to grazing with fixed preferences. Simulations with variable preferences yield better agreement with observed distributions of phytoplankton diversity. The variable grazing pressure creates refuges for less competitive phytoplankton types, which reduces exclusion and improves the representation of seasonal phytoplankton succession during blooms. Such phytoplankton communities have higher diversity and primary production than less diverse assemblages shaped by competitive exclusion. In the global model ocean, such a positive relationship between diversity and productivity can only be sustained in regions with ample nutrient supply. Developing detailed representations of zooplankton feeding might thus improve the representation of plankton diversity in models and potentially affect predictions of marine ecosystems under environmental change.
2 March
Howard Browman, Editor of ICES Journal of Marine Science: Understanding the game of scholarly publishing and the metrics used to evaluate the output of authors, journals, departments, institutes and countries
The lecture is intended to (1) provide insights into scientific publishing from the perspective of someone who has worked for a publisher and who is an experienced editor of marine science journals and (2) explain, decompose and critically evaluate the metrics used to assess scholarly performance. The lecture will be followed by a workshop - participants are encouraged to prepare questions/case studies for discussion. As an entry into the vast literature on
publication metrics, see here: http://www.int-res.com/abstracts/esep/v8/n1/
7 March
Jörgen Ripa, Department of Biology, Lund University: Adaptive radiations in space - on the evolution of alpha and beta niches
The ecological diversification of natural communities can only be understood with the appropriate “tools of the mind”, i.e. concepts. Two useful concepts within current metacommunity theory are the alpha and beta niches, where the alpha niche corresponds to a species positioning within a local, interacting community and the beta niche corresponds to adaptation to local physical conditions. An example alpha niche trait may be a choice of diet or microhabitat, whereas a beta niche trait may be tolerance to drought or cold temperatures. In the current literature, there is some debate on the niche conservatism of alpha and beta niches – is the alpha niche typically conserved relative to the beta niche, such that species slowly adapt to new physical environments but rapidly shift their niches in response to local interactions, or is it the other way around? Data supports both views. Despite the growing amount of data and interest in the evolution of alpha and beta niches, there is very little theory. I use eco-evolutionary models to study the full adaptive radiation of a competitive metacommunity, starting with a single lineage. The model output can be used to study biogeographic patterns of the speciation process as well as the relationship between the structure of the end community and the processes leading to that community. As it turns out, alpha- and beta-niche conservatism are both possible model outcomes, except in different parts of parameter space. Somewhat counter-intuitively, it is the fastest evolving trait which is most conserved during an adaptive radiation.
8 March
Christian Mohn, Aarhus University, Roskilde: Topographic controls of near-bottom flow and tracer dispersal: examples from Atlantic seamounts and Kattegat boulder reefs
Our picture of the ocean’s seafloor landscape has constantly improved over the past decade. The combination of satellite gravimetry, in-situ ship soundings and processing techniques has not only led to an unprecedented view of the true complexity of the seafloor but also provide powerful tools for researchers across a wide range of disciplines to better understand processes in the ocean at spatial scales and resolution not previously available. Research on seamounts, cold water coral hosting submarine banks and individual reefs has strongly benefited from improved seafloor bathymetry data. Flow-topography interactions generate a large variety of processes which can coexist over a wide range of spatial and temporal scales. Knowledge of the possible spectrum of physical processes and their dependence on the local physical environment is an important prerequisite to understand patterns and characteristics of entrainment and downstream advection of biological and sedimentary material in the wider context of bio-connectivity, local particle retention and large-scale transport of constituents. This presentation aims to provide an overview about important aspects of bio-physical interactions related to abrupt and complex bathymetry from large seamounts to small boulder reefs.
15 March
Florian Diekert, University of Oslo: Growth overfishing: The race to fish extends to the dimension of size
The gravity of growth overfishing is increasingly recognized. The size-distribution of fish stocks is often severely truncated, even when the overall biomass is reasonably well managed. In a first part of this article, we show how the ``race to fish'' extends to the dimension of size: Akin to the classical Bertrand competition in prices, each agent has an incentive to target fish at a smaller size. In fact, for perfect selectivity, competition between two agents is sufficient to dissipate all rents. In a second part of this article, we explore the implications of size-differentiated harvesting for ITQ regulation. We show that quotas specified in terms of numbers are far superior to those specified in terms of weight or value.
29 March
Claus Stenberg & Mikael van Deurs, DTU Aqua: Offshore wind farms and their impact on fish
Offshore wind farms (OWFs) are being constructed at a high rate due to a high demand, both economically and politically, for sources of renewable energy. But what about the fish! An OWF alters the local habitat – hard bottom habitats are added and sand bottom habitat are lost or altered. In this talk we will investigate the effects of OWF on the fish abundance and species diversity due to this change in habitat. The focal point will be a recent study we did on one of the world’s largest offshore wind farms - Horns Rev OWF - but we will also give some examples from Middelgrund and Lillgrund OWF in Øresund.
12 April
Georg Pohnert, Friedrich Schiller University, Jena: Deciphering highly dynamic chemically mediated interactions of diatoms using a combined metabolomics/bioassay approach
It is well established that unicellular algae from the plankton have established means to interact with other organisms in their environment. Especially interactions mediated by chemical compounds have gained a lot of attention during the last years. Algal exudates and metabolites stored in the cells can mediate feeding activity of herbivores, algal algal interactions but also interactions of an alga with the surrounding microbial community. We introduce an approach to address such chemically mediated interactions based on the metabolomic investigation of the cellular and released metabolites of diatoms. The metabolomic survey indicates that diatoms exhibit a high plasticity of metabolite production during their development. Metabolite concentration changes dramatically in between growth phases but also pronounced circadian variability can be observed. Our results indicate that the regulation of biosynthetic pathways in diatoms is highly dependent on environmental abiotic factors as well as biotic interactions. We used bioassays to demonstrate that the variable chemical properties of the algae are also causing pronounced variability of the chemical interaction of phytoplankton with the environment. Examples of diatom defense against herbivores, bacteria and of diatom-diatom interactions will be introduced. Consequences for future investigations of diatom physiology and chemical interactions are discussed.
19 April
Hannes Höffle, DTU Aqua: Cod in space – spatial patterns in the live of North Sea cod (Gadus morhua) from egg to juvenile
Due to predictions of future climate change, there are rising concerns about the future of the North Sea cod stock. As this is one of the stocks close to the southern limit of the species’ range, it may be among those most affected. Direct, as well as indirect effects of climate forcing may have the greatest effects on early life stages. Therefore, the present study examined the linkages between hydrography and distributional patterns of early life stages of cod as well as of several other gadoids and flatfish. Findings indicated that in the egg stage, the environment is more important for the probability of occurrence, while abundance is more under the control of spatial dependency (i.e. greater similarity the closer two samples are together). Larvae were found to be aggregated in the proximity of frontal structures and on the vertical axis, were forming distinct assemblages during the day, while they aggregated when foraging in the night. In the recent past, most 0-group cod were found in relatively shallow, warm and medium salinity water. Habitat models for the 0-group had fairly good predictive power on the sub-decadal scale (rs>0.9). On longer time scales, prediction from environmental covariates alone was not as successful and the dynamics within the population have to be taken into account. Future, more extreme, climate forcing and its effects on temperature, Atlantic inflow and river runoff may be beneficial for some species during some parts of their early life. However, the same effects can be detrimental in other stages and overall may induce a reduction in recruitment and stock size.
23 April
Øysten Varpe, Norwegian Polar Institute: Fitness, phenology, and models of optimal annual routines for zooplankton
Animal behavior and life-history strategies have evolved in response to seasonal cycles in food availability, predation risk and abiotic conditions. A common and overarching adaptation for organisms in seasonal environments is the evolution of a regular schedule of activities over the annual cycle, an annual routine. Growth, energy storage and reproduction are among the most central activities and their timing has important fitness consequences. We wish to understand which schedules that are most successful in a given environment, that is, to predict the annual routine that maximizes fitness. Here I will illustrate how models of optimal annual routines can guide us in this endeavor. I present examples from models on high latitude copepods and explain how these models can be used to study phenology, life-history strategies, and population dynamics, and importantly, to predict responses to environmental change. Specific research questions include: i) what are the annual routine consequences of earlier food availability (primary production), and ii) what is the optimal annual routine when the food source has bimodal seasonality, such as when Arctic copepods feed on both ice algae and pelagic phytoplankton? Our findings lead to discussions of central concepts in ecology and evolution such as the match-mismatch hypothesis, state-dependence, parent offspring conflict, and the reproductive modes of capital and income breeding.
26 April
Marc Andersen Borg & Eleonora Bruno, DTU Aqua: Swimming and feeding in copepod nauplii
Copepod nauplii are the most numerous metazoans in the Sea, make up a significant part of the microzooplankton and play a key role in the pelagic food webs. But despite this, our knowledge on their motion and feeding behavior is very limited. Previous studies on nauplii motility have been based on video recording with too low spatial and temporal resolution to reveal details of appendage movements and velocity patterns. We here use high speed, high magnification video to describe the kinematics of relocation jumps in 0.1 - 0.4 mm-sized nauplii of 3 species of pelagic copepods: Temora longicornis, Oithona davisae and Acartia tonsa. Although we do find some adaptations to resistance minimization, the swimming velocity patterns are highly erratic in all three species and the nauplii seem to be very energy-inefficient swimmers compared with the copepodites. We discuss the most likely reasons for this. However, compared with other crustacean nauplii, such as barnacles, the copepod naulii appear to be the more efficient swimmers. The second part of the talk will focus on how copepod nauplii detect and catch their prey. A. tonsa and O. davisae are both ambush feeding species while T. longicornis generates a feeding current. We demonstrate that both ambush feeders detect prey remotely and that preys are not captured in direct attack jump, such as has been described for adult copepods. Rather, the nauplius jumps past the prey and sets up an intermittent feeding current that pulls in the prey from behind towards the mouth. The feeding-current feeding nauplius only detects prey when it is intercepted by the setae on the feeding appendages as it arrives in the feeding current. This elicits an altered motion of the feeding appendages that draws in the prey.
2 May
Laura Pavesi, University of Potsdam and University of Rome “La Sapienza”: Spatial population structuring and genetic diversity of supralittoral mediterranean amphipods
The talk will give an overview of population genetic studies centred on Mediterranean talitrid amphipods. The Mediterranean is a semi-enclosed sea characterized by several sub-basins and thousands of km of coasts. Supralittoral talitrids colonise sandy, rocky and pebble beaches and their different microhabitats (sand, logs, wrack, under stones). For the Mediterranean area eight genera and 14 species have been described, the geographic distribution of which is highly dependent on their ability and likelihood to disperse. Active dispersal is restricted to short movements along the beach but, lacking a planktonic larval stage, passive dispersal over medium-long distances is assumed to happen via floating material carried offshore. Several studies have focused on the population genetic structure of Mediterranean talitrids in the past 17 years. These studies included several species, various sub-basins, and different molecular markers (mostly allozymes, more recently mitochondrial DNA and microsatellites). Results showed how the degree of genetic structure is likely influenced by the characteristics of the environment where species live. In particular low levels of gene flow, resulting in high genetic population
structuring, were found in those species characterized by the tendency to burrow into the sand or into rotting logs. On the contrary, high levels of gene flow and a weak population genetic structuring distinguished species from beached decaying seagrass, wrack or gravel. The working hypothesis here is that digging into the sediment or rotting logs reduces the chances to be dragged away by the action of waves, whereas the potential for this to happen is much higher for species colonizing material that can be easily displaced from the beach of origin.
10 May
Lars-Anders Hansson & Mikael Ekvall, Lund University, Sweden: Tracking the small with the smallest: Using nanobiology in tracking migration and phenotypic responses in zooplankton
In their everyday life, all organisms have to handle several threats simultaneously and make decisions and compromises that improves their fitness. When exposed to multi-threat situations, such as ultraviolet radiation (UV) and predation, many zooplankton species react with plastic responses by adjusting their protective pigmentation or migratory behaviour. A major problem, and frustration, when studying small organisms is that many questions, easily addressed for larger animals, cannot be addressed since tracking devices are too heavy for the organism to act naturally. However, recent advances in nanotechnology has made it possible to track individual animals and thereby to focus on important and urgent questions previously not possible to address. We have now initiated studies of individual responses among zooplankton, with the aim to understand how organisms handle the everyday situation of several environmental threats acting simultaneously.
15 May
Dr. J. L. Acuña, University of Oviedo, Spain: Cruising jellyfishes: why gelatinous?
Some theoretical considerations on the evolution of the gelatinous body plan in jellyfishes and other gelatinous plankton.
Dr. Jack Costello, Providence College, USA: Vorticity manipulation and maneuvering by the hydromedusa Eutonina indica
Animals moving within inertially-dominated fluid regimes transfer momentum between their bodies and surrounding fluids by creating vortices. Although medusae are known to contract their swimming bells asymmetrically in order to turn, the effect of these motions on the surrounding fluid is not well understood. Examination of the hydromedusa Eutonina indicans indicates that these medusa generate and focus vorticity in order maneuver during propulsion. Propulsive jets are formed at interfaces between fluid parcels of opposite rotational directions. The generation of propulsive jets occurs primarily via active propulsor motions, but passive structures may also influence vorticity distributions and, hence, thrust production patterns. Manipulation of vortex distributions as well as the resulting fluid jets provides insight into the mechanics of jellyfish swimming.
7 June
Simone Pigolotti, Universitat Politecnica de Catalunya, Spain: The many facets of neutral theory
Neutral theory was introduced in population genetics in the 60s to describe behavior of mutant frequencies. In the last ten years, it has been proposed that similar concepts can be used to understand ecological diversity. I will review the main ideas (and controversies) in this field, present some recent results on spatially explicit individual based models, and conclude with some theoretical ideas on the fate of neutral mutations in a fluid flow.