Dan Baird

Dan Baird
Stellenbosch University | SUN · Department of Botany and Zoology

PhD

About

101
Publications
30,134
Reads
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5,338
Citations
Citations since 2016
6 Research Items
1689 Citations
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250
Additional affiliations
January 2008 - present
Stellenbosch University
Position
  • Professor (Full)
April 2002 - May 2002
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research
Position
  • Visiting Professor
Description
  • Invited visits to the AWI In List, Sylt, Germany: April 2002 - May 2002 June 2005 - September 2005 May 2007 - August 2007 June 2009 - September 2009 July 2011 - October 2011 July 2013 - September 2013
October 1996 - March 1997
East Carolina University
Position
  • Adjucnt-Professor, Rivers Distinguisd Chair of International Studies
Description
  • Collaborative research: Visits to ECU: Oct 1996 - March 1997 Oct 1999 - February 2000 July 2003 - January 2004
Education
- December 1974
Universty of Stellenbosch
Field of study
  • Fisheries Science

Publications

Publications (101)
Article
ABSTRACT There is substantial evidence that climate warming affects terrestrial and marine ecosystems. In addition to the geographic shifts of marine species and communities, comprehensive mesocosm experiments provide insight in the behavior of species and simplified ecosystems under climate warming conditions. Food web dynamics and stability has b...
Article
In this paper, we identified seven ecological network analysis (ENA) metrics that, in our opinion, have high potential to provide useful and practical information for environmental decision-makers and stakeholders. Measurement and quantification of the network indicators requires that an ecosystem level assessment is implemented. The ENA metrics co...
Article
The food webs of the 3 main reaches of the Ems estuary were analysed for 1975- 1980 using Ecological Network Analysis (ENA). Aspects related to model aggregation at a high species resolution level (ALL SPP) or using functional groups (F-GR) and at 4 spatial scales (3 reaches and entire system) are cast in 24 balanced carbon flow models with 20 to 5...
Article
The effects of selecting system compartments in the calculation of Ecological Network Analysis (ENA) indices were studied based on data collected in the 3 main reaches of the Ems estuary. For each reach, ENA was applied to (1) a set of carbon flow models in which only the living compartments were hand-balanced, and (2) a set in which living and non...
Article
Full-text available
Food web structure and function in benthic ecosystems are a reflection of environmental conditions and change in response to both anthropogenic and natural stressors. In Jade Bay (German Wadden Sea), the intertidal macrofauna communities have been intensively studied since the 1930s, and results have revealed pronounced temporal changes in species...
Conference Paper
Full-text available
Three quantitative energy flow models consisting of 59 – 63 compartments have been constructed for the Sylt-Rømø Bight representing the stocks and flows in the ecosystem during 1995, 2007 and 2010. The network models of 2007 and 2010 models include two invasive species namely the Pacific oyster, Crassostrea gigas, and the Australasian barnacle, Aus...
Article
In this paper, we use data gathered from the Sylt–Rømø Bight Ecosystem in Germany to conduct an ecological network analysis. Specifically, we perform Network Environ Analysis to compare with results already published using EcoPath, which incorporates the ecological network analysis package NETWRK.We focus on the issue of model aggregation in that t...
Article
Full-text available
Three quantitative energy flow models have been constructed for the Sylt-Romo Bight representing the stocks and flows in the ecosystem during 1995, 2007 and 2010. The 1995 model consists of 59 compartments, while the 2007 and 2010 models have 63 compartments each. The 4 additional compartments in the 2007 and 2010 models are 2 native barnacle speci...
Article
Full-text available
The structure and function of estuarine food webs change in response to both natural and anthropogenic stresses. The construction of quantitative food webs and their analysis by means of Ecological Network Analysis provides outputs that have been used in many studies to assess system development, stress, robustness, resilience and maturity. Here we...
Article
Examples of state changes in three aquatic ecosystems (the Neuse River estuary, NC, USA, the Kromme River estuary (St. Francis Bay, South Africa), the St. Marks National Wildlife Refuge, FL, USA) over time have been quantitatively assessed using ecological network analysis (ENA). A suite of ENA indices were compared among the multiple states of the...
Data
Full-text available
In June 2009 theWadden Sea was declared by UNESCO aWorld Heritage site; a significant proclamation for one of the most unique and diverse marine ecosystems in the world. To commemorate this proclamation an international conference was held from 3–6 May 2010 under the auspices of the Estuarine & Coastal Sciences Association (ECSA) at the Alfred Wege...
Article
Full-text available
Three quantitative energy flow models have been constructed for the Sylt-Rømø Bight representing the stocks and flows in the ecosystem during 1995, 2007 and 2010. The 1995 model consists of 59 compartments, while the 2007 and 2010 models have 63 compartments each. The 4 additional compartments in the 2007 and 2010 models are 2 native barnacle speci...
Chapter
This chapter presents results from the output of ecological network analysis (ENA) of a number of coastal ecosystems, with emphasis on estuaries. Comparisons of system properties derived from ENA, specifically network analysis, are made of coastal ecosystems on global spatial scales, and over temporal scales ranging from months, to seasons, to deca...
Chapter
This chapter provides an overview of the contents of Volume 9 of the treatise. It summarizes and highlights the philosophy, theoretical framework, mathematics, and application of analytical protocols in modern ecosystems ecology and modeling. Each chapter is briefly discussed in the context of estuarine and coastal ecosystems modeling.
Book
Full-text available
9.1. Estuarine and Coastal Ecosystem Modelling: A Synthesis. Dan Baird1 and Ashish Mehta2 1Dan Baird, Department of Botany and Zoology, University of Stellenbosch, Stellenbosch, South Africa. danbaird@sun.ac.za 2Ashish Mehta, Department of Civil and Coastal Engineering, University of Florida, Gainesville, FL 32611, USA. mehta@coastal.ufl.edu 9....
Article
Flow networks of nine sub-systems consisting of 59 components each of the Sylt-Rømø Bight, German Wadden Sea, were constructed depicting the standing stocks and flows of material and energy within and between the sub-systems. Carbon, nitrogen and phosphorous were used as currencies for each sub-system, thus resulting in 27 network models, which wer...
Article
Full-text available
Catches of marine linefish by shore-based Eastern Cape recreational anglers are analysed to examine the catch composition and trends. Data were obtained from annual week-long angling competitions (Angling Week, 1978–1982), from monthly competitions (postal competitions, 1979–1982) and from the annual records of individual anglers (catch-card return...
Article
Boat-based creel surveys were used to collect catch and effort data on the shore- and boat-based linefisheries of the Kromme, Gamtoos, Swartkops, Sundays, Bushmans, Kariega, Kowie and Great Fish estuaries in the Eastern Cape, South Africa, from January 1996 to April 1997. The surveys, which were performed primarily during routine fisheries law enfo...
Article
Full-text available
Downey, N. J., Roberts, M. J., and Baird, D. 2010. An investigation of the spawning behaviour of the chokka squid Loligo reynaudii and the potential effects of temperature using acoustic telemetry. – ICES Journal of Marine Science, 67: 231–243. Spawning aggregations of chokka squid are influenced by environmental conditions. Acoustic telemetry was...
Article
In the ecological network analysis (ENA) of complex flow food webs the assumption is often made that the models characterizing the flows and stocks of ecosystems occur in a steady state where inflows equals outflows. An assessment of the system indices derived from ENA of six balanced and unbalanced system models, respectively, indicate to differen...
Article
Food webs are usually aggregated into a manageable size for their interpretation and analysis. The aggregation of food web components in trophic or other guilds is often at the choice of the modeler as there is little guidance in the literature as to what biases might be introduced by aggregation decisions. We examined the impacts of the choice of...
Article
We developed a framework to use ecological network analysis for functional assessment of large aquatic ecosystems in the context of ecosystem-based management. We established a reference domain for the Neuse River Estuary, North Carolina, USA, from changes over time. Four reference network models of the trophic structure of the estuary during early...
Article
Full-text available
Baird, D. (2009) An assessment of the functional variability of selected coastal ecosystems in the context of local environmental changes. – ICES Journal of Marine Science, 66: 1520–1527. The functioning of coastal ecosystems is greatly dependent on a wide variety of external pulses (e.g. tides, freshwater influx, seasonal trends in temperature, nu...
Article
Carbon, nitrogen, and phosphorus flow networks, consisting of 59 compartments, were constructed for the Sylt-Rømø Bight, a large shallow sea in the German Wadden Sea. These networks were analysed using ecological network analysis. Each network depicts the standing stock of each component in the ecosystem, and the flows between them. The trophic eff...
Article
Full-text available
The intertidal area of the Sylt-Romo Bight was divided into 8 benthic and 1 pelagic subsystems according to habitat nature and the unique biodiversity of each. A quantitative food web network was constructed for each of the subsystems. Each flow model consists of 56 living and 3 nonliving compartments and depicts the biomass of each, a balanced ene...
Article
Full-text available
Four Eastern Cape estuaries, the Kromme, Gamtoos, Swartkops and Sundays Estuaries have a permanent connection to the adjacent ocean, but differ in the amount of freshwater inflows as well as in the land-use patterns in their respective catchment areas. The nutrient loading to the four estuaries in terms of phosphate, nitrate, nitrite and ammonia th...
Article
Full-text available
This investigation explored the effect of the heavy metals Pb (Pb2+) and Zn (Zn2+) individually and in combination (i.e. three metal solutions) on both the brood and larval development of the burrowing crustacean, Callianassa kraussi. Egg and larval mortalities at factorial (4x7) combinations of salinity (20, 24, 30, 35 mg/l) and seven respective m...
Article
Carbon flow networks of the Kromme, Swartkops and Sundays estuaries, situated on the south coast of South Africa, were analysed using ecological network analysis. A major difference between the three estuaries is the freshwater inflow regimes: The Kromme Estuary receives very little freshwater (annual mean 0.07 m−3 s−1), the Swartkops Estuary recei...
Chapter
Full-text available
Assessments of trophic structure through ecological network analysis (ENA) have been done in a wide variety of estuarine and coastal environments. For example, some have used it to compare trophic structures within ecosystems focusing on temporal conditions (Baird and Ulanowicz 1989; Baird et al. 1998) and among ecosystems focusing on spatial condi...
Article
This investigation explored the effect of the heavy metals Pb (Pb 2+) and Zn (Zn2+) individually and in combination (i.e. three metal solutions) on both the brood and larval development of the burrowing crustacean, Callianassa kraussi. Egg and larval mortalities at factorial (4x7) combinations of salinity (20, 24, 30, 35 mg·ℓ-1) and seven respectiv...
Article
Full-text available
A detailed energy flow model consisting of 56 living and 3 non-living compartments was assembled for the intertidal area of the Sylt-Romo Bight. The model depicts the biomass of each compartment, carbon flow between the components, imports and exports, as well as an energy budget for each. The food web was analysed by means of network analysis whic...
Article
As in other eutrophied estuaries and coastal embayments, persistent hypoxia now routinely develops during summer in the mesohaline portion of the Neuse River estuary (North Carolina, USA). In response to interannual differences in hydrography, summer 1997 exhibited much more intense and widespread hypoxia than summer 1998, permitting inferences abo...
Article
Three estuaries with differing catchment use and freshwater input were investigated in terms of their nutrient status, phytoplankton biomass, freshwater inflow and salinity between 1993 and 1995. The nutrients analysed include phosphate, nitrate, nitrite, ammonia and total particulate nitrogen. All the parameters were investigated for their relatio...
Article
1.Ecological water reserves are part of the new water management philosophy in South Africa. The estuaries are threatened by excessive water abstraction from their rivers and the consequent reduction in freshwater input. This study was conducted to further improve our understanding of freshwater requirements in terms of nutrients for South African...
Article
Full-text available
We established trophic guilds of macroinvertebrate and fish taxa using correspondence analysis and a hierarchical clustering strategy for a seagrass food web in winter in the northeastern Gulf of Mexico. To create the diet matrix, we characterized the trophic linkages of macroinvertebrate and fish taxa present inHalodule wrightii seagrass habitat a...
Article
Full-text available
Groundfish surveys carried out between October 1992 and October 1996 were used to describe the demersal assemblages of the northern Benguela along the Namibian coast. Multivariate analyses indicated a clear separation between shelf and slope habitats, which were divided into three and two assemblages respectively. These divisions were distinct, wit...
Article
Full-text available
Elevated levels of heavy metals in the sediment can be a good indication of man-induced pollution. Concentrations of chrome, lead, zinc, titanium, manganese, strontium, copper and tin were measured in the sediments taken along a section of the Swartkops River and its estuary. These results showed that the highest heavy metal concentrations in both...
Article
Two software packages are available to analyze ecosystems and to compute ecosystem variables: netwrk 4.2a and ecopath 4.0. A flow model of the northern Benguela ecosystem was used to compare the outputs from these two packages. The northern Benguela ecosystem is a sub-system of the Benguela upwelling ecosystem off the coast of Southern Africa. The...
Article
Full-text available
The natural runoff from the Kromme River catchment area has been severely restricted by impoundments with storage capacities exceeding the mean annual runoff (MAR). As a consequence, freshwater input into the Kromme Estuary has been drastically reduced and the estuary itself has been labelled as 'freshwater-starved'. The annual allocation of storag...
Article
A carbon flow model was constructed of the northern Benguela upwelling ecosystem. The model consists of 22 living and two non-living compartments, depicting the biomass of each compartment and the rates of exchange between them. The only primary producer in this system is phytoplankton, whilst bacteria, heterotrophic microflagellates and microzoopl...
Article
Full-text available
The natural runoff from the Kromme River catchment area has been severely restricted by impoundments with storage capacities exceeding the mean annual runoff (MAR). As a consequence, freshwater input into the Kromme Estuary has been drastically reduced and the estuary itself has been labelled as 'freshwater-starved'. The annual allocation of storag...
Article
Estuaries of South Africa presents an authoritative and comprehensive review of the current status of that country's estuarine research and management. Contributors provide information on a wide range of topics, including geological, physical and chemical processes; diversity and productivity of plant and animal communities; interactions among estu...
Chapter
Estuaries of South Africa presents an authoritative and comprehensive review of the current status of the country's estuarine research and management. Information is provided on a wide range of topics, including geological, physical and chemical processes, diversity and productivity of plant and animal communities, interactions between estuarine or...
Chapter
Estuaries of South Africa presents an authoritative and comprehensive review of the current status of the country's estuarine research and management. Information is provided on a wide range of topics, including geological, physical and chemical processes, diversity and productivity of plant and animal communities, interactions between estuarine or...
Article
Full-text available
Nematodes from the sediments of the Swartkops estuary in Port Elizabeth, South Africa were investigated at 10 selected sites along a salinity gradient in the subtidal region at neap tide. The relation between nematode density, genera, community structure and environmental parameters including concentrations of seven heavy metals, Mn, Ti, Cr, Pb, Fe...
Article
Ecological researchers have long borrowed concepts from the theory of chemical kinetics to describe nutrient dynamics in ecosystems. Contemporary ecology, however, is in the process of creating its own suite of ideas to quantify how whole ecosystems develop. In particular, the theory of ecosystem ascendency can be applied to data on the simultaneou...
Article
Six carbon-flow networks of a seagrass ecosystem were constructed from comprehensive databases collected at three different sites during January and February 1994, respectively. The flow models, which consisted of 51 compartments each, were analysed by means of network analysis and the resultant outputs compared on spatial and temporal scales. Resu...
Chapter
Carbon flow networks of 11 coastal ecosystems were constructed from comprehensive data bases collected over the past decade. These models include upwelling systems, shallows seas, large and small estuaries, a coastal lagoon, and a beach/surf zone. The trophic and cycling structure of each model was analysed by means of network analysis in an attemp...
Article
1. Recreational and subsistence angling in South African estuaries is a small, but relevant, sector of South Africa's diverse coastal fisheries. This paper reviews these fisheries and their effects in two estuaries. 2. The composition of angler's catches in two large Eastern Cape Province estuaries has hardly changed over a period of nearly 20 year...
Article
The classical outwelling hypothesis states that small coastal embayments (e.g. estuaries, wetlands) export their excess production to inshore marine waters. In line with this notion, the present study tested whether the Swartkops estuary acts as source or sink for carbon. To this end, concentrations of dissolved inorganic carbon (DIC), dissolved or...
Article
Full-text available
We present results on changes which occurred at the ecosystem level over a period of 10 years in the relatively pristine Kromme River estuary, St. Francis Bay, South Africa. Carbon flow models were constructed for the estuary based on data collected before 1984 and again during the period 1988 to 1992. The first data set was collected during a peri...
Article
The input, exchange, recycling and export of nitrogen in the mesohaline region of Chesapeake Bay have been assessed in this study. The seasonal rate of exchanges between the 36 most important components and the roles of these in the recycling process of nitrogen in the ecosystem have been quantified. Results show that the demand for nitrogen by phy...
Article
An energy flow network was constructed for the Kromme estuary, South Africa. Extensive data, collected on this estuary, were used to calculate the energetics of each of the 27 compartments identified in this system. The model consists of three non-living and 24 living compartments. The non-living compartments were dissolved organic carbon (DOC), su...
Article
Full-text available
This paper presents results on the comparative ecology of 4 tidal estuaries: the Ythan in Scotland, the Ems-Dollard in The Netherlands and the Swartkops and Kromme estuaries, both located in the Cape Province, South Africa. Flow models (in carbon) were constructed for each of these and analysed by means of network analysis. Specific attention was g...
Article
The flux of dissolved inorganic nutrients (NH4-N, NO2-N, NO3-N, SRP) and suspended particulates (particulate organic carbon POC, and particulate inorganic carbon PIC) was measured across the mouth of a small creek draining a portion of the intertidal Spartina salt marsh in the Swartkops estuary. Direct measurements of constituent concentration, the...
Article
Full-text available
This paper presents results on the inorganic nutrient and coliform bacterial concentrations in a tide dominated marina canal system, situated in the Kromme Estuary, SI. Francis Bay. Results show an increase during the December holiday season in the concentration of NOrN of up to one to two orders of magnitude higher than during non-season periods....
Article
Full-text available
Populations of large and stunted Upogebia africana were regularly and quantitatively sampled in the Swartkops estuary. The growth of these prawns, determined by cohort analyses, was described by von Bertalanffy equations: Lt = 24,4 (1 – e−0,0583 (t + 1,8446) and Lt – 19,0 (1 – e−0,0454 (t + 4,0726) respectively, where Lt – carapace length (in mm) a...
Article
The density, biomass and population structure of Turbo sarmaticus at three different sites in the Cape St Francis region, together with its distribution along the tidal gradient, were investigated. Differences in density and population structure between sites can be attributed mainly to different degrees of exposure to wave action. An intra-specifi...
Article
Full-text available
We compare six marine ecosystems worldwide, using a network analysis of carbon flows for the Swartkops and Ems estuaries, Chesapeake Bay, the Baltic Sea and the Peruvian and Benguela upwelling regions. We find that there is an inverse correlation between the Finn Cycling Index (FCI) and the normalized internal ascendancy or system maturity (Ai:Ci)....
Article
Seasonal, tidal and phase-of-tide differences in flux were found, but generally there was a net export of phosphate during both spring and neap tides, yielding an annual net export of 24.4 tonnes. -from Authors
Chapter
The hypothesis that estuarine systems produce more material (e.g. inorganic nutrients, particulate carbon, dissolved organic carbon) that can be utilized or degraded within, and that excess material is being exported to the coastal marine environment where it may contribute to coastal ocean productivity has received considerable attention during th...
Article
Full-text available
The full site of carbon exchanges among the 36 most important components of the Chesapeake Bay mesohaline ecosystem is estimated to examine the seasonal trends in energy flow and the trophic dynamics of the ecosystem. The networks provide information on the rates of energy transfer between the trophic components in a system wherein autochthonous pr...
Article
Full-text available
The distribution and biomass of Zostera capensis (Setchell) in the Kromme Estuary is discussed in relation to substratum, nutrients, season and other abiotic parameters. It was found that substratum alone does not limit the distribution of Zostera beds and that this species can tolerate large variations in such abiotic factors as salinity and tempe...
Article
Full-text available
Totals of 44 intertidal and 19 subtidal transects were surveyed in the soft substrata of the non-marshland areas of the Swartkops Estuary. The sampling method (quadrat, suction and spear) depended on the substratum and the dominant macrobenthic species. Sampling effectiveness was measured and the numbers and standing biomasses of the 10 most abunda...
Article
The shape and dimensions of Sesarma catenata crab burrows were determined by means of polyester resin casts. Relationships between burrow entrance size and volume as well as burrow entrance size and size of the occupant crab were established. The ‘average’ crab burrow penetrated into the mud by a distance of 11·34±3·02 cm from the surface at an ang...