Fish utilization of surf-zones. Are they changing? A case study of the sheltered, warm-temperate King’s Beach
- Rishworth, Gavin M, Strydom, Nadine A, Potts, Warren M
- Authors: Rishworth, Gavin M , Strydom, Nadine A , Potts, Warren M
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124504 , vital:35619 , https://doi.org/10.1080/15627020.2014.11407616
- Description: Surf-zone fish communities and their shifts over time are generally poorly understood. The aim of this study was to compare the current surf-zone fish assemblage at King’s Beach, South Africa, to a similar study conducted three decades ago, before the collapse of many exploited shore fishes in the region. Beach seine nets (mesh sizes of 10 and 50 mm) were used to target juvenile and adult fishes bimonthly from February to August 2011 over the high tide around sunset. A total of 14 species were recorded in both the 30mand 100mseine nets. The catch in these seine nets was dominated by Pomadasys olivaceus and Liza richardsonii, and this was significantly different to three decades ago, when P. olivaceus, Sarpa salpa and Diplodus capensis dominated the catch. Important linefish species belonging to the Sparidae and Sciaenidae families were significantly smaller and less abundant in this study. Two sparids, S. salpa and Lithognathus mormyrus, which made a large contribution to the surf-zone catch three decades ago were absent during this study. Reasons for the significant shifts in the surf-zone fish community, including overexploitation of the linefish and potential habitat modification, are discussed.
- Full Text:
- Date Issued: 2015
- Authors: Rishworth, Gavin M , Strydom, Nadine A , Potts, Warren M
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124504 , vital:35619 , https://doi.org/10.1080/15627020.2014.11407616
- Description: Surf-zone fish communities and their shifts over time are generally poorly understood. The aim of this study was to compare the current surf-zone fish assemblage at King’s Beach, South Africa, to a similar study conducted three decades ago, before the collapse of many exploited shore fishes in the region. Beach seine nets (mesh sizes of 10 and 50 mm) were used to target juvenile and adult fishes bimonthly from February to August 2011 over the high tide around sunset. A total of 14 species were recorded in both the 30mand 100mseine nets. The catch in these seine nets was dominated by Pomadasys olivaceus and Liza richardsonii, and this was significantly different to three decades ago, when P. olivaceus, Sarpa salpa and Diplodus capensis dominated the catch. Important linefish species belonging to the Sparidae and Sciaenidae families were significantly smaller and less abundant in this study. Two sparids, S. salpa and Lithognathus mormyrus, which made a large contribution to the surf-zone catch three decades ago were absent during this study. Reasons for the significant shifts in the surf-zone fish community, including overexploitation of the linefish and potential habitat modification, are discussed.
- Full Text:
- Date Issued: 2015
Introduction, establishment and spread of the Southern mouthbrooder Pseudocrenilabrus philander in the Baakens River, Eastern Cape, South Africa
- Muller, Cuen, Weyl, Olaf L F, Strydom, Nadine A
- Authors: Muller, Cuen , Weyl, Olaf L F , Strydom, Nadine A
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443879 , vital:74168 , https://doi.org/10.1080/15627020.2015.1058187
- Description: 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.
- Full Text:
- Date Issued: 2015
- Authors: Muller, Cuen , Weyl, Olaf L F , Strydom, Nadine A
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443879 , vital:74168 , https://doi.org/10.1080/15627020.2015.1058187
- Description: 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.
- Full Text:
- Date Issued: 2015
The nursery role of a sheltered surf-zone in warm-temperate southern Africa
- Rishworth, Gavin M, Strydom, Nadine A, Potts, Warren M
- Authors: Rishworth, Gavin M , Strydom, Nadine A , Potts, Warren M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443651 , vital:74141 , https://hdl.handle.net/10520/EJC177697
- Description: Marine fish nurseries such as surf-zones have usually been classified as nurseries based solely on the density of pre-adult fish, yet the full suite of developmental stages are seldom assessed because of difficulties associated with sampling these habitats. The larval and early juvenile fish assemblage was studied in a sheltered surf-zone (King's Beach, South Africa), where high densities of older juveniles are known to occur. Fishes were collected fortnightly over six months using two modified seine nets. Although the surf composition included typical species for this habitat type, Gobiidae, Gobiesocidae and Haemulidae dominated the larval assemblage, which suggested that the nearby rocky structure and estuaries have an influence on the assemblage. Three species, Liza richardsonii (Mugilidae), Pomadasys olivaceus (Haemulidae) and Diplodus capensis (Sparidae), showed evidence of growth and recruitment into the surf-zone from the late larval stage. The high density of larval and juvenile fishes, the presence of more than one early life history stage and the observed growth of fishes suggests that King's Beach provides a suitable nursery habitat for several fishes.
- Full Text:
- Date Issued: 2015
- Authors: Rishworth, Gavin M , Strydom, Nadine A , Potts, Warren M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443651 , vital:74141 , https://hdl.handle.net/10520/EJC177697
- Description: Marine fish nurseries such as surf-zones have usually been classified as nurseries based solely on the density of pre-adult fish, yet the full suite of developmental stages are seldom assessed because of difficulties associated with sampling these habitats. The larval and early juvenile fish assemblage was studied in a sheltered surf-zone (King's Beach, South Africa), where high densities of older juveniles are known to occur. Fishes were collected fortnightly over six months using two modified seine nets. Although the surf composition included typical species for this habitat type, Gobiidae, Gobiesocidae and Haemulidae dominated the larval assemblage, which suggested that the nearby rocky structure and estuaries have an influence on the assemblage. Three species, Liza richardsonii (Mugilidae), Pomadasys olivaceus (Haemulidae) and Diplodus capensis (Sparidae), showed evidence of growth and recruitment into the surf-zone from the late larval stage. The high density of larval and juvenile fishes, the presence of more than one early life history stage and the observed growth of fishes suggests that King's Beach provides a suitable nursery habitat for several fishes.
- Full Text:
- Date Issued: 2015
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