Search

Seasonal deoxygenation of coastal waters has been observed with increasing frequency around the world, with consequences for ecosystem functioning and continued benthic capacity to buffer hypoxia. Here, we present a hydrodynamical-ecological model study of the Limfjord in Denmark, an example of a semi-enclosed water body affected by recurring seasonal deoxygenation. Applying observations and model results, we show that water temperature, combined with wind strength and direction are the most important controllers of short-term interannual variability of bottom oxygen, while ventilation through episodic water inflow from the North Sea and local stratification create a spatial decoupling of deoxygenation. Nutrient load to the fjord drives sustained high biological productivity, but does not affect the interannual variability to the same degree. However, high biological turnover rates likely push the system closer towards a deoxygenated state, making the fjord more sensitive to future changes in temperature, wind and ventilation by reducing the buffer capacity of the sediments. • A coastal model including ecosystem is presented for the Limfjord, Denmark. • Spatial variability of seasonal hypoxia mainly depends on stratification and inflow. • Interannual variability of hypoxia controlled by wind strength and temperature. [ABSTRACT FROM AUTHOR]

The Great Lakes Fishery Commission sponsored a 2-day workshop that sought to enhance the ability of Great Lakes agencies to understand, predict, and ideally manage fisheries production in the face of changes in natural and anthropogenic forcings (e.g., climate, invasive species, and nutrients). The workshop brought together 18 marine and freshwater researchers with collective expertise in aquatic ecology, physical oceanography, limnology, climate modeling, and ecosystem modeling, and two individuals with fisheries management expertise. We report on the outcome of a writing exercise undertaken as part of this workshop that challenged each participant to identify three needs, which if addressed, could most improve the ability of Great Lakes agencies to manage their fisheries in the face of ecosystem change. Participant responses fell into two categories. The first identified gaps in ecological understanding, including how physical and biological processes can regulate early life growth and survival, how life-history strategies vary across species and within populations, and how anthropogenic stressors (e.g., nutrient runoff, climate change) can interact to influence fish populations. The second category pointed to the need for improved approaches to research (e.g., meta-analytic, comparative, spatial translation) and management (e.g., mechanistic management models, consideration of multi-stock management), and also identified the need for improved predictive models of the physical environment and associated ecosystem monitoring programs. While some progress has been made toward addressing these needs, we believe that a continued focus will be necessary to enable optimal fisheries management responses to forthcoming ecosystem change. [ABSTRACT FROM AUTHOR]

The article presents the study which explores the effect of the dispersal of propagules from the parent's location on populations and gradients in allele frequency with variable reproduction over the lifetime of dispersal kernels. The study used a Gaussian dispersal kernel that is close to a Gaussian to obtain results with constant reproductive output over the lifetime of the organism of the adult and larval dispersal kernel in shape. The result shows variable reproduction of non-Gaussian dispersal kernels that is governed by the lifetime reproductive output of the adults in terms of the excess kurtosis of the dispersal kernel.