ERSEM 15.06: a generic model for marine biogeochemistry and the ecosystem dynamics of the lower trophic levels

The European Regional Seas Ecosystem Model (ERSEM) is one of the most established ecosystem models for the lower trophic levels of the marine food web in the scientific literature. Since its original development in the early nineties it has evolved significantly from a coastal ecosystem model for the North Sea to a generic tool for ecosystem simulations from shelf seas to the global ocean. The current model release contains all essential elements for the pelagic and benthic parts of the marine ecosystem, including the microbial food web, the carbonate system, and calcification. Its distribution is accompanied by a testing framework enabling the analysis of individual parts of the model. Here we provide a detailed mathematical description of all ERSEM components along with case studies of mesocosm-type simulations, water column implementations, and a brief example of a full-scale application for the north-western European shelf. Validation against in situ data demonstrates the capability of the model to represent the marine ecosystem in contrasting environments.

Identifying species and ecosystem sensitivities.

Executive Summary The programme of work was commissioned in September 1998 to supply information to underpin the UK’s commitments to protection and conservation of the ecosystems and biodiversity of the marine environment under the 1992 OSPAR Convention on the Protection of the Marine Environment of the North East Atlantic. The programme also provided support for the implementation of the Biodiversity Convention and the EU Habitats Directive. The MarLIN programme initiated a new approach to assessing sensitivity and recoverability characteristics of seabed species and biotopes based on structures (such as the seabed biotopes classification) and criteria (such as for assessing rarity and defining ‘sensitivity’) developed since 1997. It also developed tools to disseminate the information on the Internet. The species researched were those that were listed in conventions and directives, included in Biodiversity Action Plans, or were nationally rare or scarce. In addition, species were researched if they maintained community composition or structure and/or provided a distinctive habitat or were special to or especially abundant in a particular situation or biotope At its conclusion in August 2001, the work carried out under the contract with DETR/DEFRA had: · Developed protocols, criteria and structures for identifying ‘sensitivity’ and ‘recoverability’, which were tested by a programme management group. · Developed a database to hold research data on biology and sensitivity of species and biotopes. · Defined the link between human activities and the environmental factors likely to be affected by those activities. · Developed a user-friendly Web site to access information from the database, on the sensitivity and recoverability characteristics of over 100 species and basic information on over 200 species. Additionally, the project team have: · Brought together and facilitated discussion between current developers and users of electronic resources for environmental management, protection and education in the conference ‘Using Marine Biological Information in the Electronic Age’ (19-21 July 1999). · Contributed to the development of Ecological Quality Objectives for the North Sea (Scheveningen, 11- 3 September 1999 and subsequent papers). · Provided detailed information on species as a supplement to the National Biodiversity Network Gateway demonstration www.searchnbn.net. · Developed a peer-reviewed approach to electronic publication of updateable information. · Promoted the contract results and the MarLIN approach to the support of marine environmental management and protection at European research fora and, through the web site, internationally. The information available through the Web site is now being used by consultants and Government agencies. The DEFRA contract has been of critical importance in establishing the Marine Life Information Network (MarLIN) programme and has encouraged support from other organisations. Other related work in the MarLIN programme is on-going, especially to identify sensitivity of biotopes to support management of SACs (contract from English Nature in collaboration with Scottish Natural Heritage), to access data sources (in collaboration with the National Biodiversity Network) and to establish volunteer recording schemes for marine life. The results of the programme are best viewed on the Web site (www.marlin.ac.uk). Three reports have been produced during the project. A final report detailing the work undertaken, a brochure ‘Identifying the sensitivity of seabed ecosystems’ and a CD-ROM describing the programme and demonstrating the Web site have been delivered as final products in addition to the Web site.

Sub-fossil Insects and ecosystem dynamics in wetlands; implications for biodiversity and conservation.

We review the uses of fossil insects, particularly Coleoptera (beetles) and Chironomidae (non-biting midges) from ancient deposits to inform the study of wetland ecosystems and their ecological and restoration processes. In particular, we focus on two contrasting ecosystems, drawing upon research undertaken by us on British raised mire peats and shallow lake systems, one an essentially terrestrial ecosystem, the other aquatic, but in which wetland insects play an important and integral part. The study of raised mire peats suggests that faunal stability is a characteristic of these wetland systems, over what appear to be extensive periods of time (up to several millennia), whilst studies of shallow lake ecosystems over recent timescales indicates that faunal instability appears to be more common, usually driven by increasing eutrophication. Drawing upon a series of fossil Coleoptera records spanning several thousand years from Hatfield Moors, south Yorkshire, we reconstruct in some detail the mire’s ontogeny and fluctuations in site hydrology and vegetation cover, illustrating the intimate association between substrate, topography and peat development. A comparison between fossil and modern beetle populations indicates that the faunal characteristics of this mire and its adjacent neighbour, Thorne Moors, become established during the early phases of peat development, including its rare endemics, and that the faunal biodiversity on the sites today is dictated by complex site histories. The over-riding characteristic of these faunas is of stability over several thousand years, which has important implications for the restoration of degraded sites, especially those where refugial areas are limited. In contrast, analyses of fossil Chironomidae from shallow lakes allow researchers to track changes in limnological status and while attempts have been made to reconstruct changes in nutrient levels quantitatively, the chironomids respond indirectly to such changes, typically mediated through complex ecosystem dynamics such as changes in fish and/or macrophyte communities. These changes are illustrated via historic chironomid stratigraphies and diversity indices from a range of shallow lakes located across Britain: Slapton Ley, Frensham Great Pond, Fleet Pond, Kyre Pool and Barnes Loch. These sites have shown varying degrees of eutrophication over recent timescales which tends to be associated with a decline in chironomid diversity. While complex functional processes exist within these ecosystems, our evidence suggests that one of the key drivers in the loss of shallow lake chironomid diversity appears to be the loss of aquatic macrophytes. Overall, while chironomids do show a clear response to altered nutrient regimes, multi-proxy reconstructions are recommended for a clear interpretation of past change. We conclude that if we are to have a better understanding of biota at the ecosystem level we need to know more of the complex interactions between different insect groups as well as with other animal and plant communities. A palaeoecological approach is thus crucial in order to assess the role of insect groups in ecosystem processes, both in the recent past and over long time scales, and is essential for wetland managers and conservation organisations involved in long term management and restoration of wetland systems.

Rapid ecosystem response to abrupt climate changes during the last glacial period in western Europe, 40-16 ka

We present a high-resolution and independently dated multiproxy lake sediment record from the paleolake at Les Echets in southeastern France that displays synchronous changes in independent limnic and terrestrial ecosystem proxies, in concert with millennial-scale climate oscillations during the last glacial period. Distinct lake-level fluctuations, low lake organic productivity, and open, treeless vegetation indicate cold and dry conditions in response to Heinrich events. Alternating phases of higher and low lake organic productivity, stratified surface waters and long-lasting lake ice cover, decreased or increased catchment erosion, and tree-dominated or herb-dominated vegetation resemble Dansgaard-Oeschger interstadial-stadial variability. Transitions between different ecological states occurred in as little as 40-230 yr and seem to have been controlled by the position of the Polar Front. Ecosystem response after 30 ka suggests that local climate conditions became more important. Our results demonstrate that all parts of the terrestrial system responded to the abrupt and dramatic climatic changes associated with Dansgaard-Oeschger and Heinrich events, and that regional factors modulated ecosystem response.

Biodiversity loss and ecosystem functioning: Distinguishing between number and identity of species

Given currently high rates of extinction, it is critical to be able to predict how ecosystems will respond to loss of species and consequent changes in community structure. Much previous research in this area has been based on terrestrial systems, using synthetically assembled communities. There has beer! much less research on inter-trophic effects in different systems, using in situ removal experiments. Problems with the design of early experiments have made it difficult to determine whether reductions in ecosystem functioning in low diversity treatments were due to the number of species present or merely to the reduced likelihood of including particular (

Multiproxy evidence for terrestrial and aquatic ecosystem responses during the 8.2 ka cold event as recorded at Hojby So, Denmark

A sediment succession from Hojby So, a lake in eastern Denmark, covering the time period 9400-7400 cal yr BP was studied using high-resolution geochemistry, magnetic susceptibility, pollen, macrofossil, diatom, and algal pigment analysis to investigate responses of the terrestrial and aquatic ecosystems to the 8.2 ka cold event. A reduced pollen production by thermophilous deciduous tree taxa in the period c. 8250-8000 cal yr BP reveal that the forest ecosystem was affected by low temperatures during the summer and winter/early-spring seasons. This finding is consistent with the timing of the 8.2 ka cold event as registered in the Greenland ice cores. At Hojby So, the climate anomaly appears to have started 200-250 yr earlier than the 8.2 ka cold event as the lake proxy data provide strong evidence for a precipitation-induced distinct increase in catchment soil erosion beginning around 8500 cal yr BP. Alteration of the terrestrial environment then resulted in a major aquatic ecosystem change with nutrient enrichment of the lake and enhanced productivity, which lasted until c. 7900 cal yr BP. (C) 2009 University of Washington. Published by Elsevier Inc. All rights reserved.

Sequentially assembled food webs and extremum principles in ecosystem ecology

Successional changes during sequential assembly of food webs were examined. This was carried out by numerical methods, drawing one species at a time from a species pool and obtaining the permanent (persistent) community emerging at each step. Interactions among species were based on some simple rules about body sizes of consumers and their prey, and community dynamics were described in terms of flows of biomass density.

Biodiversity and ecosystem processes in shallow coastal waters: an experimental approach

The relationship between biodiversity and ecological processes is currently the focus of considerable research effort, made all the more urgent by the rate of biodiversity loss world-wide. Rigorous experimental approaches to this question have been dominated by terrestrial ecologists, but shallow-water marine systems offer great opportunities by virtue of their relative ease of manipulation, fast response times and well-understood effects of macrofauna on sediment processes. In this paper, we describe a series of experiments whereby species richness has been manipulated in a controlled way and the concentrations of nutrients (ammonium, nitrate and phosphate) in the overlying water measured under these different treatments. The results indicate variable effects of species and location on ecosystem processes, and are discussed in the context of emerging mainstream ecological theory on biodiversity and ecosystem relations. Extensions of the application of the experimental approach to species-rich, large-scale benthic systems are discussed and the potential for novel analyses of existing data sets is highlighted. (C) 2002 Elsevier Science B.V. All rights reserved.

Detecting the effects of diversity on measures of ecosystem function: experimental design, null models and empirical observations

Here we present a novel experimental approach to examine the relationship between diversity and ecosystem Function. We develop four null predictive models, with which to differentiate between the 'sampling effect' - the chance inclusion of a highly productive species, and 'species complementarity' - the complementary use of resources by species that differ in their niche or resource use. We investigate the effects of manipulating species and functional richness on ecosystem function in marine benthic system and using empirical data from our own experiments we illustrate the application of these models.