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Emergent effects of structural complexity and temperature on predator–prey interactions

  • Authors: Wasserman, Ryan J , Alexander, Mhairi E , Weyl, Olaf L F , Barrios‐O'Neill, Daniel , Froneman, P William , Dalu, Tatenda
  • Date: 2016
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/69190 , vital:29444 , https://doi.org/10.1002/ecs2.1239
  • Description: Ephemeral aquatic environments are important habitats for a variety of species. They are highly variable with regards to vegetation structure and physico‐chemical features that potentially mediate outcomes of biotic interactions. Multiple environmental variables and their emergent impacts on the relationship between prey consumption rate by a predator and prey density (functional response), however, are rarely assessed. Here, we investigated the combined effects of temperature and habitat complexity on the functional response of the freshwater predatory notonectid Enithares sobria on the cladoceran prey organism Daphnia longispina. A Type II functional response was observed for E. sobria predating on D. longispina and while temperature and habitat complexity had no effect on the response type, these environmental variables interacted with consequences for the magnitude of the functional responses. Overall, structural complexity favored the predator as greater consumption was observed in the most complex habitat treatment. Temperature effects were also evident although these effects were not unidirectional with regard to treatment factor gradients as predators were the most successful at intermediary temperatures. Furthermore, there was a complex interplay between habitat complexity and temperature, with attack rates being greatest at low and high complexities within intermediate temperatures, while at zero complexity attack rates were greatest at the lowest temperature. The effect of habitat on handling times was only evident in the low temperature treatments which decreased steadily with each increase in complexity. Through the application of functional responses the synergistic effects of multiple environmental drivers on predator–prey interaction outcomes have been highlighted, adding insight into how interactions among species may be affected by natural or artificially induced environmental variability.
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  • Date Issued: 2016

Examining intraspecific multiple predator effects across shifting predator sex ratios:

  • Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/150119 , vital:38941 , https://doi.org/10.1016/j.baae.2020.03.002
  • Description: Predator-predator interactions, or “multiple predator effects” (MPEs), are pervasive in the structuring of communities and complicate predictive quantifications of ecosystem dynamics. The nature of MPEs is also context-dependent, manifesting differently among species, prey densities and habitat structures. However, there has hitherto been a lack of consideration for the implications of intraspecific demographic variation within populations for the strength of MPEs. The present study extends MPE concepts to examine intraspecific interactions among male and female predators across differences in prey densities using a functional response approach. Focusing on a copepod-mosquito model predator-prey system, interaction strengths of different sex ratio pairs of Lovenula raynerae were quantified towards larval Culex pipiens complex prey, with observations compared to both additive and substitutive model predictions.
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  • Date Issued: 2020

Fatty acid profiles reveal temporal and spatial differentiation in diets within and among syntopic rocky shore suspension-feeders:

  • Authors: Richoux, Nicole B , Vermeulen, Ilke , Froneman, P William
  • Date: 2014
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/143346 , vital:38238 , doi: 10.3354/meps10581
  • Description: Regional and temporal variations in the diets of rocky shore suspension-feeders (the volcano barnacle Tetraclita serrata, the brown mussel Perna perna and the reef-building polychaete Gunnarea gaimardi) were assessed using fatty acid profiling. Specimens were collected up-current and down-current of a river mouth in 2 coastal regions ~50 km apart along southeastern South Africa during March and July of 2009. One of the rivers represents a marine-dominated system, and the other a freshwater-dominated system. Our aims were to assess any dietary differences among the 3 suspension-feeders, spatial changes in diet within each species (at regional and local scales—50 and 15 km, respectively), and temporal changes in diet within each species.
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  • Date Issued: 2014

Fish predation regimes modify benthic diatom community structures: experimental evidence from an in situ mesocosm study

  • Authors: Wasserman, Ryan J , Vink, Tim J F , Dalu, Tatenda , Froneman, P William
  • Date: 2015
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/68052 , vital:29190 , https://doi.org/10.1111/aec.12255
  • Description: Publisher version , Diatoms are important primary producers in shallow water environments. Few studies have assessed the importance of biological interactions in structuring these communities. In the present study, benthic diatom community structure in relation to manipulated food webs was assessed using in situ mesocosms, whereby predator-free environments and environments comprising two different fish species were assessed. Zooplankton abundance, settled algal biomass and the diatom community were monitored over a 12‐day period across each of the three trophic scenarios. Differences among treatments over time were observed in zooplankton abundances, particularly copepods. Similarly, the benthic diatom community structure changed significantly over time across the three trophic treatments. However, no differences in total algal biomass were found among treatments. This was likely the result of non‐diatom phytoplankton contributions. We propose that the benthic diatom community structure within the mesocosms was influenced by trophic cascades and potentially through direct consumption by the fish. The study highlights that not only are organisms at the base of the food web affected by predators at the top of the food web, but that predator identity is potentially an important consideration for predator–prey interaction outcomes with consequences for multiple trophic levels.
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  • Date Issued: 2015

Growth and longevity of Exosphaeroma hylocoetes (Isopoda) under varying conditions of salinity and temperature

  • Authors: Henninger, Tony O , Froneman, P William , Booth, Anthony J , Hodgson, Alan N
  • Date: 2010
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/124571 , vital:35630 , https://doi.org/10.3377/004.045.0118
  • Description: Numerous studies have documented the importance of both temperature and salinity in influencing aquatic crustacean metabolic processes such as respiration and growth. For example, increased water temperatures have been shown to increase respiration rates in various species of shrimp (Chen & Nan 1993; Spanonopoulos-Hernándeza et al. 2005; Allan et al. 2006), and copepods (Isla & Perissinotto 2004). The response of invertebrates to changes in salinity is more complex, largely reflecting their evolutionary origins (Kinne 1966). For example, juvenile blue swimming crabs, Portunus pelagicus, displayed significantly faster growth and higher survival in response to increasingsalinity (Romano & Zeng 2006). Additional factors that may influence the growth rates of crustaceans include photoperiod (Gambardella et al. 1997), food availability (Shuster & Guthrie 1999) and sex (Newman et al. 2007).
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  • Date Issued: 2010

Hyperbenthic and pelagic predators regulate alternate key planktonic copepods in shallow temperate estuaries

  • Authors: Wasserman, Ryan J , Vink, Tim J F , Kramer, Rachel , Froneman, P William
  • Date: 2014
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/68224 , vital:29220 , https://doi.org/10.1071/MF13233
  • Description: Publisher version , Although predation has been identified as an important community driver, the role of predator diversity in structuring estuarine zooplankton has not been assessed. As such, we investigated the effects of two different zooplanktivorous fish species on the estuarine zooplankton community during a 12-day mesocosm study. Three experimental treatments were established, whereby natural zooplankton communities were subject to either (1) no predatory pressure, (2) predation by a pelagic predator (Monodactylus falciformis) or (3) predation by a hyper-benthic predator (Glossogobius callidus). The pelagic feeding M. falciformis fed largely on the numerically dominant mid-water copepod species, Paracartia longipatella. In contrast, the hyper-benthic fish had a greater predatory impact on the less numerically dominant copepod, Pseudodiaptomus hessei, which demonstrates strong diel vertical migration. Variations in prey-population regulation are ascribed to the distinct behavioural differences of the predators, and mediated by the differences in behaviour of the copepod species.
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  • Date Issued: 2014

Impacts of marine biogeographic boundaries on phylogeographic patterns of three South African estuarine crustaceans

  • Authors: Teske, Peter R , McQuaid, Christopher D , Froneman, P William , Barker, Nigel P
  • Date: 2006
  • Language: English
  • Type: Article
  • Identifier: vital:6548 , http://hdl.handle.net/10962/d1006004 , http://dx.doi.org/10.3354/meps314283
  • Description: The South African coastline comprises 3 main biogeographic provinces: (1) the cool-temperate west coast, (2) the warm-temperate south coast, and (3) the subtropical east coast. The boundaries between these regions are defined by changes in species compositions and hydrological conditions. It is possible that these affect phylogeographic patterns of coastal organisms differently, depending on the species’ ecologies and modes of dispersal. In the present study, genealogies of 3 estuarine crustaceans, each characterized by a different mode of passive dispersal and present in more than one biogeographic province, were reconstructed using mtDNA COI sequences, and the impacts of biogeographic boundaries on their phylogeographic patterns were compared. The species were (mode of dispersal in brackets): (1) the mudprawn Upogebia africana (planktonic larvae), (2) the isopod Exosphaeroma hylecoetes (adult rafting), and (3) the cumacean Iphinoe truncata (adult drifting). Two major mtDNA lineages with slightly overlapping distributions were identified in U. africana (the species with the highest dispersal potential). The other 2 species had 3 mtDNA lineages each, which were characterized by strict geographic segregation. Phylogeographic breaks in U. africana and E. hylecoetes coincided with biogeographic boundaries, whereas the phylogeographic patterns identified in I. truncata may reflect persistent palaeogeographic patterns. Ecological factors and modes of dispersal are likely to have played a role in both cladogenesis of the different lineages and in the establishment of their present-day distribution patterns.
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  • Date Issued: 2006

In situ feeding rates of the copepods, Pseudodiaptomus hessei and Acartia longipatella, in a temperate, temporarily open/closed Eastern Cape estuary

  • Authors: Froneman, P William
  • Date: 2004
  • Language: English
  • Type: text , Article
  • Identifier: vital:6901 , http://hdl.handle.net/10962/d1011754
  • Description: Size-fractionated chlorophyll-a (chl-a) concentrations and the in situ grazing rates of the copepods, Pseudodiaptomus hessei and Acartia longipatella, were assessed seasonally at the temporarily open/closed Kasouga estuary situated along the southeast coast of southern Africa. Total integrated chl-a concentration ranged between 1.17 and 12.18 mg chl-a m^(–3) and was always dominated by small phytoplankton cells (<20 μm), which comprised up to 86% (range 64–86%) of the total pigment. Total zooplankton abundance ranged between 2676 and 62 043 individuals m^(–3). These copepods numerically dominated the zooplankton counts, accounting for between 79% and 91% of the total. Gut pigment concentrations of the two species at night were significantly higher than the daytime values (P<0.05 in all cases). The observed pattern could be related to the marked diurnal vertical migration patterns exhibited by the copepods. Gut evacuation rates of P. hessei during the study ranged between 0.29 and 0.77 h^(–1) and between 0.39 and 0.58 h^(–1) for A. longipatella. The rate of gut pigment destruction for P. hessei and A. longipatella ranged between 55% and 81% and between 88% and 92% of the total chl-a ingested, respectively. The combined grazing impact of the two copepods ranged between 0.65 and 4.37 mg chl-a m^(–3), or between 4.3% and 35.9% of the available chl-a in the water column. Variations in the grazing activity of the two species could be attributed largely to seasonality in water temperature and shifts in the phytoplankton community structure and zooplankton abundance.
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  • Date Issued: 2004

Influence of mouth status on population structure of southern African endemic estuarine-spawning ichthyofauna in a temperate, temporarily open/closed estuary

  • Authors: Tweddle, Gavin P , Froneman, P William
  • Date: 2015
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/68071 , vital:29195 , https://doi.org/10.2989/16085914.2015.1051940
  • Description: Publisher version , The effect of mouth status on the population structure of three endemic estuarine-spawning fish species was assessed using seine nets from November 2005 to October 2007 in the temporarily open/closed Mpekweni Estuary, Eastern Cape, South Africa. Collectively, these three species accounted for more than 60% of the total fish abundance within the estuary. Monthly length frequency data were analysed. Two species, Gilchristella aestuaria and Glossogobius callidus, displayed normally distributed populations throughout, with recruitment/abundance peaks between spring and autumn, and were unaffected by open mouth and extended marine connection conditions. Atherina breviceps, however, displayed multiple modal peaks in its combined population distribution, suggesting a greater influence of mouth condition on its population structure. Retrospective analyses of the various cohorts for A. breviceps identified peaks in recruitment/abundance during summer, coinciding with open-mouth conditions and, to a lesser extent, with overwash events. This study highlights the importance of mouth phase, not only on the recruitment and population distribution of marine-spawning species, but also on estuarine-spawning fish in temporarily open/closed estuaries along the South African coastline.
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  • Date Issued: 2015

Largest reported groups for the Indo-Pacific bottlenose dolphin (Tursiops aduncus) found in Algoa Bay, South Africa: trends and potential drivers

  • Authors: Bouveroux, Thibaut N , Caputo, Michelle , Froneman, P William , Plön, Stephanie
  • Date: 2018
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/67913 , vital:29168 , https://doi.org/10.1111/mms.12471
  • Description: Publisher version , This study investigates how group size of Indo‐Pacific bottlenose dolphins (Tursiops aduncus) changes temporally, spatially, and/or with predominant behavior at two discreet sites along the Eastern Cape coastline of South Africa: Algoa Bay and the Wild Coast. The mean group size of bottlenose dolphins was large with an average of 52 animals. Significantly larger groups were observed in Algoa Bay ( = 60, range = 1–600) than off the Wild Coast ( = 32.9, range = 1–250). In Algoa Bay, the mean group size increased significantly over the study period, from an average 18 animals in 2008 to 76 animals in 2016. Additionally, the largest average and maximum group sizes ever reported both in South Africa and worldwide, were recorded in Algoa Bay (maximum group size = 600). Neither season nor behavior had a significant effect on mean group size at both sites. Similarly environmental variables such as the depth and substrate type also had no influence on group size. It remains unclear which ecological drivers, such as predation risk and food availability, are leading to the large groups observed in this area, and further research on abundance and distribution of both predators and prey is necessary.
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  • Date Issued: 2018

Monitoring the oceanic flow between Africa and Antarctica: report of the first Good Hope cruise

  • Authors: Ansorge, Isabelle J , Speich, S , Lutjeharms, Johan R E , Goni, G J , Rautenbach, C J de W , Froneman, P William , Rouault, M , Garzoli, S
  • Date: 2005
  • Language: English
  • Type: Article
  • Identifier: vital:6832 , http://hdl.handle.net/10962/d1007568
  • Description: The Southern Ocean plays a major role in the global oceanic circulation, as a component of the Meridional Overturning Circulation, and it is postulated that it has a great influence on present-day climate. However, our understanding of its complex three-dimensional dynamics and of the impact of its variability on the climate system is rudimentary. The newly constituted, international GoodHope research venture aims to address this knowledge gap by establishing a programme of regular observations across the Southern Ocean between the African and Antarctic continents. The objectives of this programme are fivefold: (1) to improve understanding of Indo-Atlantic inter-ocean exchanges and their impact on the global thermohaline circulation and thus on global climate change; (2) to understand in more detail the influence these exchanges have on the climate variability of the southern African subcontinent; (3) to monitor the variability of the main Southern Ocean frontal systems associated with the Antarctic Circumpolar Current; (4) to study air-sea exchanges and their role on the global heat budget, with particular emphasis on the intense exchanges occurring within the Agulhas Retroflection region south of South Africa, and (5) to examine the role of major frontal systems as areas of elevated biological activity and as biogeographical barriers to the distribution of plankton. We present here preliminary results on the physical and biological structure of the frontal systems using the first GoodHope transect that was completed during February-March 2004.
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  • Date Issued: 2005

Nature and source of suspended particulate matter and detritus along an austral temperate river–estuary continuum, assessed using stable isotope analysis

  • Authors: Dalu, Tatenda , Richoux, Nicole B , Froneman, P William
  • Date: 2016
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/68012 , vital:29181 , https://doi.org/10.1007/s10750-015-2480-1
  • Description: Publisher version , Ecologists are interested in the factors that control, and the variability in, the contributions of different sources to mixed organic materials travelling through lotic systems. We hypothesized that the source matter fuelling mixed organic pools in a river–estuary continuum varies over space and time. Samples of the mixed organic pools were collected along a small temperate river (Kowie River) in southern Africa during early and late spring, summer and winter. The C:N ratios of suspended particulate matter (SPM) collected during summer and winter indicated that the lower reaches of the system had similar organic matter contributions. Stable isotope analysis in R revealed that aquatic macrophytes were significant contributors to SPM in the upper reaches. Bulk detritus had large allochthonous matter components in the lower reaches, and contributions of aquatic macrophytes and benthic algae were high (>50%) in the upper to middle reaches. The evaluation of organic matter contributions to SPM and detritus along the river–estuary continuum provided a baseline assessment of the nature and sources of potential food for consumers inhabiting different locations during different seasons. Incorporating SPM and detritus spatio-temporal variations in food web studies will improve our understanding of carbon flow in aquatic systems.
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  • Date Issued: 2016

Occurrence of Indo-Pacific bottlenose dolphins (Tursiops aduncus) off the Wild Coast of South Africa using photographic identification:

  • Authors: Caputo, Michelle , Bouveroux, Thibaut , Froneman, P William , Shaanika, Titus , Plön, Stephanie
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/160367 , vital:40439 , https://0-doi.org.wam.seals.ac.za/10.1111/mms.12740
  • Description: The present study represents the first reported boat‐based photographic identification study of Indo‐Pacific bottlenose dolphins (Tursiops aduncus) off the Wild Coast of southeast South Africa. This area is known for the annual sardine run, which attracts apex predators to the region during the austral winter. Dedicated photo‐identification surveys were conducted along this coast at three different study sites in February, June, and November of each year from 2014 to 2016.
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  • Date Issued: 2020

Physical and biological processes at the Subtropical Convergence in the South-west Indian Ocean

  • Authors: Froneman, P William , Ansorge, Isabelle J , Richoux, Nicole B , Blake, Justin , Daly, Ryan , Sterley, Jessica A , Mostert, B , Heyns, Elodie R , Sheppard, Jill N , Kuyper, B , Hart, N , George, C , Howard, J , Mustafa, E , Pey, F , Lutjeharms, Johan R E
  • Date: 2007
  • Language: English
  • Type: Article
  • Identifier: vital:6966 , http://hdl.handle.net/10962/d1012030
  • Description: A detailed hydrographic and biological survey was conducted in the region of the Subtropical Convergence in the Indian sector of the Southern Ocean in April 2007. Hydrographic data revealed that the subsurface expression of the Subtropical Convergence (at 200 m), marked by the 10°C isotherm, appeared to meander considerably between 41°S and 42°15’S. Total surface chlorophyll- a concentration was low and ranged from 0.03 to 0.42 µg l–1 and was always dominated by the pico- (<2 µm) and nano- (2–120 µm) size classes, which contributed between 81% and 93% of the total pigment. The total chlorophyll-a integrated over the top 150m of the water column showed no distinct spatial trends, and ranged from 12.8 to 40.1mg chl-a m–2. There were no significant correlations between the total integrated chlorophyll- a concentration and temperature and salinity (P > 0.05). The zooplankton community was dominated, numerically and by biomass, by mesozooplankton comprising mainly copepods of the genera, Oithona,Paraeuchaeta, Pleuromamma, Calanus and Clausocalanus. An exception was recorded at those stations in the region of the front where the tunicate, Salpa thompsoni, dominated the total zooplankton biomass.
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  • Date Issued: 2007

Physical and biological variability in the Antarctic Polar Frontal Zone: report on research cruise 103 of the MV SA Agulhas

  • Authors: Froneman, P William , Ansorge, Isabelle J , Vumazonke, Lukhanyiso U , Gulekana, A , Bernard, K S , Webb, Arthur C M , Leukes, W , Risien, C M , Thomalla, S , Hermes, J , Knott, M , Anderson, D , Hargey, N , Jennings, M E , Veitch, J , Lutjeharms, Johan R E , McQuaid, Christopher D
  • Date: 2002
  • Language: English
  • Type: Article
  • Identifier: vital:6910 , http://hdl.handle.net/10962/d1011863
  • Description: A detailed hydrographic and biological survey was carried out in the region of the South-west Indian Ridge during April 2002. Hydrographic data revealed that the Andrew Bain Fracture Zone, centred at 30oE, 50oS, functions as an important choke point to the flow of the Antarctic Circumpolar Current, resulting in the convergence of the Antarctic Polar Front (APF) and the southern branch of the Sub-Antarctic Front (SSAF). Total chlorophyll-a concentration and zooplankton biomass were highest at stations occupied in the vicinity of two frontal features represented by the APF and SSAF. These data suggest that the region of the South-west Indian Ridge is an area of elevated biological activity and probably acts as an important offshore feeding area for the top predators on the Prince Edward Islands.
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  • Date Issued: 2002

Preliminary evidence for the organisation of a bacterial community by zooplanktivores at the top of an estuarine planktonic food web

  • Authors: Wasserman, Ryan J , Matcher, Gwynneth F , Vink, Tim J F , Froneman, P William
  • Date: 2015
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/68237 , vital:29222 , https://doi.org/10.1007/s00248-014-0505-3
  • Description: Publisher version , As part of a larger investigation, the effect of apex predation on estuarine bacterial community structure, through trophic cascading, was investigated using experimental in situ mesocosms. Through either the removal (filtration) or addition of specific size classes of planktonic groups, four different trophic scenarios were established using estuarine water and its associated plankton. One such treatment represented a “natural” scenario in which stable apex predatory pressure was qualified. Water samples were collected over time from each of the treatments for bacterial community evaluation. These samples were assessed through pyrosequencing of the variable regions 4 and 5 of the bacterial 16S rRNA gene and analysed at the species operational taxonomic unit (OTU) level using a community procedure. The blue-green group dominated the samples, followed by Proteobacteria and Bacteroidetes. Samples were the most similar among treatments at the commencement of the experiment. While the bacterial communities sampled within each treatment changed over time, the deviation from initial appeared to be linked to the treatment trophic scenarios. The least temporal deviation-from-initial in bacterial community was found within the stable apex predatory pressure treatment. These findings are consistent with trophic cascade theory, whereby predators mediate interactions at multiple lower trophic levels with consequent repercussions for diversity.
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  • Date Issued: 2015

Recovery of the critically endangered river pipefish, Syngnathus watermeyeri, in the Kariega Estuary, Eastern Cape province

  • Authors: Vorwerk, Paul D , Froneman, P William , Paterson, Angus W
  • Date: 2007
  • Language: English
  • Type: text , Article
  • Identifier: vital:6965 , http://hdl.handle.net/10962/d1012028
  • Description: An intensive ichthyofaunal survey in the permanently open Kariega Estuary along the Eastern Cape coast has identified a breeding population of the critically endangered river pipefish, Syngnathus watermeyeri, within the middle and upper reaches of the system. This is the first recorded capture of this species in the estuary for over four decades. We suggest that the presence of S. watermeyeri is the result of the heavy rainfall within the region, which contributed to the establishment of optimum habitat requirements (mesohaline conditions and increased food availability) of the pipefish.
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  • Date Issued: 2007

Research cruise of the Scandinavian/South African Antarctic expedition, December 1997 to February 1998

Residency patterns and migration dynamics of adult bull sharks (Carcharhinus leucas) on the east coast of southern Africa:

  • Authors: Daly, Ryan , Smale, Malcolm J , Cowley, Paul D , Froneman, P William
  • Date: 2014
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/143235 , vital:38213 , doi:10.1371/journal.pone.0109357
  • Description: Bull sharks (Carcharhinus leucas) are globally distributed top predators that play an important ecological role within coastal marine communities. However, little is known about the spatial and temporal scales of their habitat use and associated ecological role. In this study, we employed passive acoustic telemetry to investigate the residency patterns and migration dynamics of 18 adult bull sharks (195–283 cm total length) tagged in southern Mozambique for a period of between 10 and 22 months. The majority of sharks (n = 16) exhibited temporally and spatially variable residency patterns interspersed with migration events. Ten individuals undertook coastal migrations that ranged between 433 and 709 km (mean  = 533 km) with eight of these sharks returning to the study site.
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  • Date Issued: 2014

Spawning and nest guarding of the river goby (Glossogobius callidus) from the Eastern Cape province of South Africa

  • Authors: Wasserman, Ryan J , Vink, Tim J F , Woodford, Darragh J , Froneman, P William
  • Date: 2015
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/68144 , vital:29203 , https://doi.org/10.1111/aje.12228
  • Description: Publisher version , Introduction: The River goby, Glossogobius callidus (Smith 1937), occurs naturally in rivers and the upper reaches of estuaries along the eastern seaboard of southern Africa (Whitfield, 1998; James et al., 2007; Wasserman, Strydom & Wooldridge, 2010). This fish species is among the most abundant of fishes in many river systems of the region and is considered an important predator in these habitats, feeding on invertebrates and small fish (Whitfield, 1998; Strydom & Neira, 2006; Wasserman, 2012; Wasserman et al., 2014). Despite this, ecological information on this goby is sparse and to date, no published records on the biology of the species exist. The urgent need for such information was recently highlighted in a study that identified G. callidus as a potentially invasive species, given its ability to rapidly establish in novel environments (Woodford et al., 2013). The present study therefore endeavoured to determine the reproductive guild to which G. callidus belong and describe aspects of their spawning. This was performed by closely observing wild caught, mature G. callidus in aquaria over a 25-day period.
  • Full Text: false
  • Date Issued: 2015
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