TRY plant trait database – enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Spatial and temporal variability in the larval fish assemblage of a warm temperate South African estuary, with notes on the effects of artificial channelling

The composition, abundance, distribution and seasonality of larval fishes was investigated in the permanently open Kowie Estuary on the temperate southeast coast of South Africa. Larval fishes were sampled within the estuary and marina for a period of two years. Samples were collected seasonally at 14 different sampling stations along the main channel and within the artificially-channelled marina by means of boat-based plankton tows. A total of 11 128 larval fishes were collected, representing 23 families and 38 taxa. Clupeidae and Gobiidae were the dominant fish families, contributing 47.0% and 24.7%, respectively, to the total catch. Common species included Gilchristella aestuaria (Clupeidae), Omobranchus woodii (Blennidae), an unidentified blenniid, Caffrogobius gilchristi, Caffrogobius nudiceps, Glossogobius callidus, Psammogobius knysnaensis (Gobiidae) and Solea turbynei (Soleidae) with the other species contributing <1% to the total catch. Catches varied significantly with season and were highest in summer. Estuary-resident species dominated the overall catch (91%). A notable absence of postflexion larvae and early juveniles characterized the artificial channels. This was attributed to the absence of shallow, marginal water habitat, typical of a good estuarine nursery area. The steep walls of the artificial channels reduce refuge areas, increasing predation by larger piscivores.African Zoology 45(2): 195–212 (October 2010

Plankton dynamics associated with the convergence zone of a shear front in the permanently open Kowie Estuary, South Africa

Estuarine frontal systems are thought to play an important role in plankton  accumulations in estuaries. However, knowledge surrounding these estuarine circulation patterns is not clear, and consensus regarding the importance of fronts has yet to be reached. A full appraisal of the plankton in frontal systems in the estuary was undertaken. Ichthyoplankton, zooplankton and phytoplankton were collected from in and out of the frontal systems in the Kowie Estuary, using two WP2 plankton nets. Plankton was identified and abundance calculated. Various water quality parameters were also recorded in and out of the front and make up an  important part of determining the physical difference between the separated water masses. Values for in and out of the frontal region were determined in order to make comparisons between the different areas. All data was tested for normality and homogeneity of variance. Differences between in and out of the frontal region were determined using ANOVA or Kruskal-Wallis tests. Multiple linear regression was used to determine the relationships between water quality variables and plankton  abundances. Community analysis was also run on the data in order to determine community dynamics associated with frontal system convergence and downwelling.Key words: ichthyoplankton, phytoplankton, zooplankton, estuarine fronts, water quality

Description of larval fish composition, abundance and distribution in nine south and west coast estuaries of South Africa

The composition, abundance and distribution of larval fishes from nine south and west coast estuaries from South Africa was investigated by plankton tow once per season between June 2003 and March 2004. A total of 49 274 early stage fishes were caught, comprising nine orders, 20 families, 29 genera and 47 taxa. Seven species accounted for 93.4% of the total catch in these estuaries, namely Gilchristella aestuaria (78.8%), Caffrogobius gilchristi (6.2%), Psammogobius knysnaensis (3.5%), C. nudiceps (2.5%), Parablennius sp. (2.4%), Omobranchus woodi (2.1%) and Atherina breviceps (1.9%). The majority (70%) of identified species are endemic to southern Africa and 96.4% of the larvae caught were estuary-resident species. Larval fish assemblages in the sampled estuaries exhibited the same seasonal and spatial patterns described for temperate estuaries both in South Africa and worldwide. Larval fish were more abundant in summer and in the mesohaline zone. The assemblages were less diverse and dominated by fewer species than temperate estuaries along the south east coast of South Africa. The differences found in composition and density of the larval fish assemblages from south and west coast estuaries result from the biogeography of the area and the differences in freshwater inflow.Keywords: ichthyoplankton, cool-temperate, community structure, biogeography, estuary type

Introduction, establishment and spread of the Southern mouthbrooder Pseudocrenilabrus philander in the Baakens River, Eastern Cape, South Africa: short communication.

This paper provides evidence for the extralimital establishment and spread of Pseudocrenilabrus philander in the Baakens River, Eastern Cape, South Africa. Since the first occurrence record at a single locality in 1994 this species has now spread throughout the river and the population contains both reproductive adults and juveniles. Gut content analysis demonstrated potential dietary overlap with native fishes and predation on fish larvae. Pseudocrenilabrus philander in the Baakens River therefore satisfies all criteria for an invasive species in this river and was categorised as invasive using a unified framework for biological invasions

Development and Ossification of the Feeding Apparatus in the Larvae of Two Co-occurring Species of Kob (Sciaenidae), \u3ci\u3eArgyrosomus japonicus\u3c/i\u3e and \u3ci\u3eArgyrosomus inodorus\u3c/i\u3e, in South Africa

The teeth of the oral jaws of two sympatric species of Argyrosomus, Argyrosomus japonicus and Argyrosomus inodorus, found along the South African coast developed first on the premaxilla and then on the dentary of the lower jaw. Teeth were observed on the premaxilla of A. inodorus [head length (L-H) = 10 mm; notochord length (L-N) = 27 mm] at a smaller size than in A. japonicus (L-H = 12 mm; L-N = 47 mm). The ventral elements of the gill arches (hypo- and basibranchials) were not ossified by the end of preflexion. The fifth ceratobranchial began ossifying and possessed pharyngeal teeth by 12 mm L-H (L-N = 47 mm) in A. japonicus and 11 mm L-H (L-N = 32 mm) in A. inodorus. To complement the osteological data, stomach contents were also analysed as a proxy for feeding apparatus functionality. Prey were first present in the stomach of A. japonicus at 12 mm L-H (L-N = 47 mm) and only 22% of the stomachs contained no prey suggesting that A. japonicus is already actively foraging by preflexion. In comparison, 83% of the stomachs of A. inodorus contained no prey and a single prey item was present in the largest examined specimen (L-H = 16 mm; L-N = 54 mm). Elements of the feeding apparatus begin to ossify early during ontogeny. While the overall pattern of ossification is similar between the two species, A. japonicus may be able to begin feeding at smaller head lengths relative to A. inodorus in their nursery habitats

Composition, abundance, distribution and seasonality of larval fishes in the Sundays Estuary, South Africa

The larval fish assemblage was studied in the permanently open Sundays Estuary on the southeast coast of South Africa. Seasonal samples were collected between winter 2007 and autumn 2009 at eight sites along the estuary by means of boat-based plankton tows using two modified Working Party 2 (WP2) nets. Salinity ranged from 1.5–36.5 and temperature from 11.6–26.8°C during the study period. A total of 8174 larval and early juvenile fishes were caught, representing 12  families and 23 taxa. The Clupeidae, Gobiidae and Blenniidae were the numerically dominant fish families. Common species included Gilchristella aestuarias (Clupeidae), Omobranchus woodi (Blenniidae), Caffrogobius gilchristi, Glossogobius callidus (Gobiidae), Liza dumerilii and Myxus capensis (Mugilidae), largely reflecting the adult assemblage of the estuary. Catches varied significantly between seasons, but not between sites and salinity zones within the estuary. Highest catches were recorded in summer (mean of 464 and 928 larvae per 100 m3 in 2008 and 2009, respectively). Species diversity also varied seasonally, with highest diversity occurring during summer. Highest larval fish density occurred in the euhaline zone while the oligohaline zone supported the highest diversity. Estuarine-resident  species (category I) dominated the system (91%). The preflexion stage of development dominated the catches suggesting a high degree of local production in the Sundays Estuary. Larval sizes of the estuarine-resident G. aestuarias and catadromous species M. capensis tended to increase towards the middle and upper reaches of the estuary. Important variables regulating larval fish dynamics in the Sundays Estuary included salinity, temperature and turbidity.Key words: estuary-dependent, nursery, salinity zones, developmental stage

Preliminary assessment of contaminants in the sediment and organisms of the Swartkops Estuary, South Africa

Urban estuaries are susceptible to metal and organic pollution, yet most remain understudied in South Africa with respect to the presence, concentrations and distribution of contaminants. Metal and organic chemical concentrations were assessed in sediment and organisms from different trophic levels in the lower reaches of the Swartkops Estuary. Species sampled included Upogebia africana (Malacostraca: Upogebiidae), Gilchristella aestuaria (Clupeidae), Psammogobius knysnaensis (Gobiidae), Mugil cephalus (Mugilidae), Lichia amia (Carangidae), Argyrosomus japonicus (Sciaenidae), Pomadasys commersonnii (Haemulidae) and Larus dominicanus (Avis: Laridae). This study is one of the most comprehensive studies to date assessing pollution levels in a food web in estuaries in South Africa. Due to biomagnification, higher concentrations of Arsenic, Lead, Mercury and Cadmium were found in the juveniles stages of popular angling fishes. High concentrations of Cadmium and Arsenic were recorded in the liver of L. amia, A. japonicus and P. commersonnii which exceed international quality food guidelines. Eggs from the gull, L. dominicanus, showed detectable concentrations of PCB

The role of estuarine type in characterizing early stage fish assemblages in warm temperate estuaries, South Africa

Assemblages of early stage fishes (larval and early juvenile stages) were  investigated and compared in seven permanently open and five intermittently open estuarine systems on the warm temperate Eastern Cape coast of South Africa. Estuarine type, by virtue of mouth state and prevailing physico chemical conditions, played a defining role in the structure of these fish   assemblages. Clupeidae and Gobiidae were the dominant fish families in both estuarine types. Permanently open estuaries were characterized by the predominance of larvae and early juveniles of estuary dependent marine fish species while estuary resident fishes dominated intermittently open estuaries. Seasonal changes were observed in species density and diversity in both  estuarine types. Species richness and diversity were highest in the permanently open Swartkops Estuary that is characterized by large nursery habitat availability. Species diversity was high in estuaries with a good supply of freshwater, that results in good recruitment of estuary dependent marine species. Similarly, freshwater deprived estuaries also displayed high species diversity and this was due to the higher incidence of marine straggler species in these systems. Salinity zones appeared to play a  significant role in both species density and the presence or absence of species in both estuarine types. Mesohaline zones were found to be the most productive in terms of accumulator regions for larval stages.Key words: fish larvae, estuary type, abundance, diversity, mesohaline region