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Re-Descriptions of Some Southern African Scyphozoa: out with the Old and in with the New

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Re-Descriptions of Some Southern African Scyphozoa: out with the Old and in with the New i Re-descriptions of some southern African Scyphozoa: out with the old and in with the new Simone Neethling Department of Biodiversity & Conservation Biology University of the Western Cape P. Bag X17, Bellville 7535 South Africa A thesis submitted in fulfillment of the requirements for the degree of MSc in the Department of Biodiversity and Conservation Biology, University of the Western Cape. Supervisor: Mark J. Gibbons November 2009 ii I declare that “Re-descriptions of some southern African Scyphozoa: out with the old and in with the new” is my own work, that it has not been submitted for any degree or examination at any other university, and that all the sources I have used or quoted have been indicated and acknowledged by complete references. iii To my family: Brian, Esther, Michelle and Joan, for their constant encouragement and support, for convincing me every day that anything is possible. To God, for providing me with the spiritual guidance to complete this thesis. iv TABLE OF CONTENTS Abstract.................................................................................................................1 Chapter 1: Introduction ...................................................................................2 Chapter 2: Materials and Methods ...............................................................18 Morphological data collection .....................................................................18 Morphological data analyses .......................................................................19 DNA analyses...............................................................................................22 Chapter 3: Chrysaora fulgida Systematics...................................................................................................25 Description ...................................................................................................25 Variation.......................................................................................................27 Remarks........................................................................................................28 Chapter 4: Chrysaora africana Systematics...................................................................................................36 Description ...................................................................................................36 Variation.......................................................................................................38 Remarks........................................................................................................38 Acknowledgements............................................................................................44 References .........................................................................................................45 Tables .................................................................................................................62 Figure Captions .................................................................................................79 Figures ...............................................................................................................83 Appendices ........................................................................................................97 Chapter 5: Crambionella stuhlmanni Title Page....................................................................................................112 Abstract ......................................................................................................113 Introduction ................................................................................................114 Materials and Methods...............................................................................117 Morphological data collection......................................................117 Morphological data analyses........................................................118 DNA analyses ...............................................................................121 Systematics.................................................................................................124 Description .................................................................................................124 Variation.....................................................................................................126 Remarks......................................................................................................126 References ..................................................................................................130 Tables .........................................................................................................140 v Figure Captions ..........................................................................................149 Figures........................................................................................................151 Appendices.................................................................................................162 1 Abstract Two species of Chrysaora are described from the northern Benguela ecosystem: C. fulgida and C. africana. These species can be diagnosed by a combination of morphological features including lappet and tentacle number, shape of lappets, colouration patterns (alive), shape of the proximal portion of radial septa, gastrovascular pouch shape, point of attachment of gonads and the presence or absence of small raised nematocyst warts on the exumbrellar surface. Objective, quantitative statistical analyses coupled with molecular sequence data support the qualitative morphological dissimilarity observed, as these analyses unambiguously diagnose C. fulgida and C. africana as two distinct species. There is a strong superficial resemblance between the C. fulgida material described here and the preserved specimens of C. hysoscella examined at the Natural History Museum, London. Thorough investigation does however allow the separation of these two species. Morphological features found to be dissimilar were the proximal portion of the manubrium, gastrovascular pouch shape and the presence or absence of sperm sacs. Objective, quantitative statistical analyses support these findings. Nuclear sequence variation suggests considerable divergence between the two species but additional molecular work is needed. Keywords: Chrysaora, northern Benguela ecosystem, taxonomy, systematics, morphological analyses, molecular analyses. 2 Introduction The Benguela Current is one of the four major eastern boundary current systems. Prevailing coastal southerly and south-easterly winds along the west coast of southern Africa fuel the upwelling of cool, nutrient rich waters (Shannon, 1985). The Benguela ecosystem is traditionally divided, at Lüderitz, into northern and southern subregions where upwelling tends to be more seasonal (Shannon, 1985). The coastal region surrounding Lüderitz, where the continental shelf is narrowest and prevailing winds strongest, is characterized by perennial upwelling and it is considered southern Africa’s most intense upwelling cell (Shannon, 1985). Upwelling of cool nutrient rich water prompts concentrated phytoplankton growth in the upper photic zone (Shannon, 1985) which in turn supports plentiful fish stocks and numerous seabirds, seals and sharks as top predators (Boyer et al., 2000). Characteristic of an ecosystem with high levels of primary production is increased bacterial decomposition that can strip surrounding water of oxygen (Chapman and Shannon, 1985). This often leads to hypoxic and at times anoxic conditions that may be associated with sulphide eruptions (Bakun and Weeks, 2006) and mass mortalities of marine life (Boyer et al., 2000): hypoxic waters have been linked to depleted abundances of commercially valuable fish species (Woodhead et al., 1997). Environmental anomalies and anthropogenic activities are thought to have adversely affected the productive northern Benguela ecosystem resulting in a highly modified and deficient ecosystem (Boyer et al., 2000). The northern is traditionally considered the more productive of the two Benguela ecosystems (Carr, 2001). Intense upwelling is associated with high concentrations of diatoms, whereas quiescent or post-upwelling periods favour dinoflagellates; as upwelling intensities vary so do nutrient concentrations determining the dominant plankton group (Sakko, 1998). The 3 zooplankton community, dominated by copepods and euphausiids, all occur at low levels of species diversity but high abundance/biomass (Gibbons and Hutchings, 1996; Sakko, 1998). Prominent for its once abundant fish stocks, Namibian waters supported numerous commercially valuable species that in turn provided important resources to the Namibian economy. Species are generally divided into three groups dependant on the zone occupied in the marine environment (Sakko, 1998; Boyer et al., 2000). In the epipelagic zone clupeiforms such as round herring Etrumeus whiteheadi, sardines Sardinops sagax, anchovy Engraulis encrasicolis well as juvenile horse mackerel Trachurus trachurus capensis (Perciformes) are found. Perciforms such as chub mackerel Scomber japonicus, horse mackerel and geelbek Atractoscion aequidens are found in the mesopelagic zone and the demersal zone is dominated by Cape hake Merluccius capensis and M. paradoxus (Gadiformes) and the bearded goby Sufflogobius bibarbatus (Perciformes). Unfortunately unsustainable fishing practices carried out in the late 20th century have
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