Prof. Gavin Maneveldt

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https://hdl.handle.net/10566/1536

Position:	Professor
Department:	Biodiversity and Conservation Biology Programme
Faculty:	Faculty of Natural Science
Qualifications:	BSc, BSc(Hons), MSc, PhD (UWC)
	FGASA Honorary SKS (Marine Guiding)
	Research publications in this repository
ORICD iD	0000-0002-5656-5348
More about me:	here and here
Tel:	021 959 2342/2301	Fax:	021 959 2312
Email:	gmaneveldt@uwc.ac.za

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Now showing 1 - 20 of 42

Ecological significance of deep-layer sloughing in the eulittoral zone coralline alga, Spongites yendoi (Foslie) Chamberlain (Corallinaceae, Rhodophyta) in South Africa.
(Elsevier, 1994) Keats, Derek; Wilton, P.; Maneveldt, Gavin
The crustose coralline alga Spongites yendoi (Foslie) Chamberlain (Corallinaceae, Rhodophyta) dominates the lower eulittoral zone along the South Coast of South Africa, together with the limpet Patella cochlear Born. This coralline alga was previously shown to undergo a deep-layer sloughing twice a year, as well as continuous epithallial sloughing. The hypothesis that deep-layer sloughing could perform an antifouling function was tested by determining the percentage cover of fleshy algae developing in a limpet exclusion experiment on live and killed coralline. Substantial fleshy algal cover developed in both limpet removal treatments, negating any possible antifouling function of deep-layer sloughing. A measurable decrease in the mean thickness of the coralline population was noted during periods of sloughing. A thicker crustose coralline, Leptophytum ferox (Foslie) Chamberlain & Keats, grew more slowly and was much more heavily burrowed and more weakly attached than S. yendoi. These results are consistent with a hypothesis that deep-layer sloughing contributes to the alga's relatively thin thallus, thereby conferring the advantages of faster growth and stronger attachment. However, further studies are still needed to evaluate these hypotheses further.
Leptophytum foveatum Chamberlain & Keats (Rhodophyta, Corallinales) retaliates against overgrowth by other encrusting algae
(Elsevier, 1994) Keats, Derek; Maneveldt, Gavin
The encrusting coralline alga, Leptophytum foveatum, is the most abundant crustose alga in the lower eulittoral zone at Yzerfontein and other exposed sites on the West Coast of South Africa. The surface of this species is usually imbricate (appears scaly) as a result of the aparently spontaneous regeneration of margins at the surface of the thallus. The thicker, fleshy, brown crustose alga, Ralfsia verrucosa, usually overgrows the margins of the thinner L. foveatum; however, L. foveatum counteracts this overgrowth by regenerating margins at the thallus surface, and these are able to grow up and over the encroaching margin of R. verrucosa. Experiments in which these regenerated margins were removed showed that the regenerated margins are able to slow or stop the encroachment of R. verrucosa. It is suggested that the regeneration of thallus margins at the surface, away from the primary thallus margin, allows L. foveatum to maintain the advantages of being thin (e.g. more rapid lateral growth), but also gain some of the advantages of being thick (e.g. improved competitive ability).
Clathromorphum tubiforme sp. nov. (Rhodophyta, Corallinaceae) in South Africa with Comments on Generic Characters
(Walter de Gruyter, 1995) Chamberlain, Yvonne; Norris, R.E.; Keats, Derek; Maneveldt, Gavin
A nongeniculate, crustose coralline alga (Rhodophyta, Corallinaceae) from South Africa, is found growing epiphytically on fronds of species of the geniculate genus Ampiroa. Analysis of the vegetative and reproductive morphology and anatomy of the alga shows that it belongs to the subfamily Melobesioideae and genus Clathromorphum. It is the only known representative of the genus in South Africa. It has tetrasporangial conceptacles that are significantly smaller than those of any other described species of the genus and it is described as the new species Clathromorphum tubiforme. The diagnostic features of Clathromorphum and other genera of the Melobesioideae are discussed and it is considered that, among melobesioid genera, Clathromorphum is probably most closely related to Melobesia.
Two new melobesioid algae (Corallinales, Rhodophyta), Synarthrophyton robbenense sp. nov. and S. munimentum sp. nov., in South Africa and Namibia
(International Phycological Society, 1997) Keats, Derek; Maneveldt, Gavin
Synarthrophyton robbenense sp. nov. and S. munimentum sp. nov., the fourth and fifth species in this apparently southern hemisphere genus, are described from southern Africa. Synarhrophyton robbenense occurs on rock and shells in the subtidal zone. Its thalli are minutely warty, with the surface covered by short, narrow protuberances that are fused into elongate, scrolled structures. The surface [scanning electron microscopy (SEM)] is of the Leptophytum type. Mature tetraibisporangial conceptacles have raised rims and sunken pore plates. The pore plates are composed of filaments made up of two or three cells plus an enlarged epithallial cell. The pore canal is lined by filaments with cells that do not differ in size or shape from those of the other filaments making up the pore plate. Cells of filaments within the tetrasporangial and bisporangial conceptacle rim are narrower and more elongate than cells of the pore plate and surrounding vegetative filaments. Tetralbisporangial pores are surrounded by five to eight rosette cells that tilt somewhat toward the pore in surface SEM view. Tetraibisporangial conceptacles do not become buried in the thallus, but are shed on senescence, often leaving shallow craters on the surface. Synarthrophylon munimenlum occurs on rocks and shells in low-shore tide pools, and on rock, shells, and kelp holdfasts in the subtidal zone. Thalli are usually smooth, occasionally warty, but never show protuberances that are fused into scrol l-like structures. The thallus surface (SEM) is made up of Leptophytum-type epithallial cells. Tetral bisporangial conceptacle roofs are volcano-shaped with a raised peripheral rim and sunken pore plate. The pore plates are composed of filaments made up of five to seven cells plus an epithallial cell. The rosette cells that surround the tetral bisporangial pore are distinct from surrounding roof cells (SEM, surface view) in being narrower and sunken below the level of the surrounding pore plate. The pore canal is lined by filaments with cells that do not differ in size or shape from those of the other filaments making up the pore plate. Cells of filaments within the tetrasporangial and bisporangial conceptacle rim are more or less similar in size and shape to cells of the pore plate and surrounding vegetative filaments.
Of dead man's fingers, cord weed and hanging wrack: common brown seaweeds of the Cape Peninsula
(Botanical Society of South Africa, 2000) Maneveldt, Gavin; Frans, Rene
In this, the second in the series on common intertidal seaweeds of the Cape Peninsula, we look at the brown seaweeds common to our rocky shores, with the exception of kelp, which will be covered in the next issue of Veld & Flora. Unlike the green seaweeds mentioned in the previous issue, these brown seaweeds are generally slower growing and are less tolerant of salinity and temperature extremes and thus more prone to desiccation stress. They therefore tend to occur lower down on the shore than the green seaweeds.
Of sea lettuces and green sea intestines: common intertidal green seaweeds of the Cape Peninsula
(Botanical Society of South Africa, 2000) Maneveldt, Gavin; Frans, Rene
Most of us know seaweed as that slippery stuff growing on the rocks or lying strewn along the beach at low tide making the beach smell. But do we really know much about them? Although not entirely true, seaweeds (or marine algae) are generally considered to be plants because they use solar energy to produce carbohydrate food from carbon dioxide and water (photosynthesis). They are simpler than land plants as they have no roots or shoots. Seaweeds absorb nutrients directly from the seawater; and therefore have no need for roots or complex conductive tissue. Some large seaweeds do however have root-like structures called holdfasts and leaf-like fronds that act like shoots. The photosynthetic pigments they possess reflect certain colours of light, producing what appear to be green, brown and red seaweeds, and thus they are divided into three main groups: green brown and red. In this article we examine some of the green seaweeds that occur in the Cape Peninsula.
Of purple laver, tongue weed and hedgehog seaweed: common red seaweeds of the Cape Peninsula
(Botanical Society of South Africa, 2001) Maneveldt, Gavin; Frans, Rene
The fourth part of our series on the common intertidal seaweeds of the Cape Peninsula looks at the red seaweeds, which form by far the largest group of seaweeds on the Peninsula and dominate the mid to lower intertidal area to a large extent. Like the brown seaweeds many of the reds are fleshy and bulky and generally occur lower down the shore because they are less tolerant of salinity and temperature extremes than some of the common green seaweeds.
Of sea bamboo, split fan kelp and bladder kelp: three common kelp species of the Cape Peninsula and West Coast
(Botanical Society of South Africa, 2001) Maneveldt, Gavin; Frans, Rene
The third part in our series on the common intertidal seaweeds of the Cape Peninsula looks at the kelps, the giant brown seaweeds that occur in the subtidal and intertidal gullies of the Cape Peninsula and the west coast. Like trees an ancient forest, kelp dominate the canopy of the subtidal zone in the cool, nutrient-rich waters of the South African west coast. Kelp is the largest and fastest growing of the seaweeds, growing as much as 13 mm in a day. Some of these seaweeds as the giant kelp (Macrocystis pyrifera) of central and southern California are known to grow to over 30 m in length.
Of dinner plate, cochlear and pacman corallines: seven common intertidal encrusting red seaweeds of the Cape Peninsula
(Botanical Society of South Africa, 2001) Maneveldt, Gavin; Frans, Rene
In the fifth and final part of this series of articles on common intertidal seaweeds of the Cape Peninsula, we look at encrusting coralline algae. These encrusting coralline and red seaweeds are widespread in shallow waters in all the world’s oceans, where they often cover close to 100% of rocky substrates. Nowhere are they more important than in the ecology of coral reefs. Not only do encrusting coralline algae help cement the reef together, but they make up a considerable portion of the mass of the reef itself and are important primary products and food for certain herbivores.
The chromista
(Wiley Online, 2003) Maneveldt, Gavin; Keats, Derek
As a group, the chromists show a diverse range of forms from tiny unicellular, flagellates to the large brown algae known as kelp. Molecular studies have confirmed the inclusion of certain organisms once considered Fungi, as well as some heterotrophic flagellates. Despite their diversity of form and feeding modes, a few unique characters group these organisms.
Don't cut that 'grass'
(Botanical Society of South Africa, 2006) Marais, Karen; Maneveldt, Gavin
Introduction: Have you ever noticed the abundance of wildflowers on public open spaces during spring in Cape Town? I suppose some Capetonians would be aware of Rondebosch Common and the astonishing botanical diversity it contains, including many threatened species. However, it appears that very few people are aware of the many other public open spaces that may be just as precious and put on a spectacular spring flower show. But for how much longer?
Abalone farming in South Africa: an overview with perspectives on kelp resources, abalone feed, potential for on-farm seaweed production and socio-economic importance
(Elsevier, 2006) Troella, M. D.; Robertson-Andersson, Deborah; Anderson, Robert J.; Bolton, John J.; Maneveldt, Gavin; Halling, C.; Probyn, T.
The South African abalone cultivation industry has developed rapidly and is now the largest producer outside Asia. With a rapid decline in wild abalone fisheries, farming now dominates the abalone export market in South Africa. Kelp (Ecklonia maxima) constitutes the major feed for farmed abalone in South Africa, but this resource is now approaching limits of sustainable harvesting in kelp Concession Areas where abalone farms are concentrated. This paper gives an overview of the development of the South African abalone industry and analyses how abalone farming, natural kelp beds and seaweed harvesting are interlinked. It discusses options and constraints for expanding the abalone industry, focussing especially on abalone feed development to meet this growing demand. Kelp will continue to play an important role as feed and kelp areas previously not utilised may become cost-effective to harvest. There are many benefits from on-farm seaweed production and it will probably be a part of future expansion of the abalone industry. Abalone waste discharges are not at present regarded as a major concern and farming brings important employment opportunities to lower income groups in remote coastal communities and has positive spill-over effects on the seaweed industry and abalone processing industry.
You use seaweeds for that?
(Botanical Society of South Africa, 2006) Maneveldt, Gavin
Introduction: The word seaweed is commonly used, yet to refer to these marine algae as 'weeds' is very far from the truth. Together with microscopic algae called phytoplankton and other photosynthetic organisms, seaweeds are responsible for all primary production in the oceans and therefore form the basis of the food chain in the sea. Although we often cannot smell or taste them, many ingredients in our foods and household products come from the sea and from seaweeds. They are therefore both directly and indirectly valuable to humans. Seaweeds assimilate minerals directly from the sea and are thought to be the single most nutritious foods that you can eat. Rich in trace elements and vitamins, many of them may frequently contain more protein than meat and more calcium than milk.
The role of encrusting coralline algae in the diets of selected intertidal herbivores
(Springer Verlag, 2006) Maneveldt, Gavin; Wilby, Deborah; Potgieter, Michelle; Hendricks, Martin G.J.
Kalk Bay, South Africa, has a typical south coast zonation pattern with a band of seaweed dominating the mid-eulittoral and sandwiched between two molluscan-herbivore dominated upper and lower eulittoral zones. Encrusting coralline algae were very obvious features of these zones. The most abundant herbivores in the upper eulittoral were the limpet, Cymbula oculus (10.4 + 1.6 m-2; 201.65 + 32.68 g.m-2) and the false limpet, Siphonaria capensis (97.07 + 19.92 m-2; 77.93 + 16.02 g.m-2). The territorial gardening limpet, Scutellastra cochlear, dominated the lower eulittoral zone, achieving very high densities (545.27 + 84.35 m-2) and biomass (4630.17 + 556.13 g.m-2), and excluded all other herbivores and most seaweeds, except for its garden alga and the encrusting coralline alga, Spongities yendoi (35.93 + 2.26 % cover). For the upper eulittoral zone, only the chiton Acanthochiton garnoti 30.5 + 1.33 % and the limpet C. oculus 2.9 + 0.34 %, contained encrusting coralline algae in their guts. The lower eulittoral zone limpet, Scutellastra cochlear also had a large percentage of encrusting coralline algae in its gut with limpets lacking gardens having higher (45.1 + 1.68 %) proportions of coralline algae in their guts than those with gardens (25.6 + 0.8 %). Encrusting coralline algae had high organic contents, similar to those of other encrusting and turfy algae, but higher organic contents than foliose algae. Radula structure, grazing frequencies as a percentage of the area grazed (upper eulittoral 73.25 + 3.60 % d-1; lower eulittoral 46.0 + 3.29 % d-1), and algae organic content provided evidence to support the dietary habits of the above herbivores. The data show that many intertidal molluscs are actively consuming encrusting coralline algae and that these seaweeds should be seen as an important food source.
Structure of rhodolith beds from 4 to 55 meters deep along the southern coast of Espírito Santo State, Brazil
(Universidad Autónoma de Baja California, 2007) Amado-Filho, Gilberto M.; Maneveldt, Gavin; Manso, R.C.C.; Marins-Rosa, B.V.; Pacheco, M.R.; Guimarães, S.M.P.B.
Rhodoliths are one of the most extensive benthic communities of the Brazilian continental shelf, but their structure is poorly known. The richest marine flora of Brazil’s coastal zone is found in Espírito Santo State and its diversity has been partly associated with the presence of extensive areas of rhodoliths, extending from the intertidal zone to 120 m across the continental shelf. One species of kelp, Laminaria abyssalis, is endemic to this area and occurs between 45 and 120 m depth. Our objective was to determine the density and physical dimensions of the superficial rhodoliths between 4 and 55 m depth in the southern region of Espírito Santo State. The study area was 3 to 45 km offshore. Samples were obtained in 2004 and 2005 by Scuba diving in three depth zones: 4–18 m, 25–30 m and 50–55 m. Transect lines and video images were used to determine rhodolith density. The diameter and sphericity of at least 60 individuals from each zone were measured. Rhodolith size increased and density decreased from the shallow to the deeper zones. Spheroidal was the typical shape throughout the depth zones. Five rhodolith-forming genera were identified: Lithothamnion, Lithophyllum, Hydrolithon, Neogoniolithon and Sporolithon. Epibenthic biomass and species richness over the rhodolith bed in the shallow zone was lowest in winter, likely the result of disturbance caused by typical winter storms. Changes in light and temperature are probably the most important factors in the changes observed in the rhodolith beds from the deepest zones.
A comparison of various seaweed-based diets and formulated feed on growth rate of abalone in a land-based aquaculture system
(Springer, 2007) Naidoo, Krishni; Maneveldt, Gavin; Ruck, Kevin; Bolton, John J.
The effects of different diets on growth in the cultured South African abalone, Haliotis midae (Linnaeus), was investigated. Growth of juvenile Haliotis midae was monitored on a commercial abalone farm over a period of 9-months in an experiment consisting of 9 treatments with 4 replicates (n = 250 individuals per replicate). The treatments were: fresh kelp (Ecklonia maxima) blades (seaweed control); Abfeed® (formulated feed control); kelp + Abfeed®; dried kelp pellets; dried kelp blades; dried kelp stipes; fresh kelp with the epiphyte Carpoblepharis flaccida; a mixed diet (Gracilaria gracilis, Ulva lactuca, and kelp) and a rotational diet (abalone were fed 1 of the 9 treatments for the first week and them kelp for the next 3 weeks). Results show that abalone grow well on all fresh seaweed combinations, but do best on a mixed diet. The likely reason for the success of the mixed diet is that the red and green seaweed was farm grown, with an increased protein content. Dried kelp in any form produced poor growth. Abalone fed on the mixed diet grew at 0.066 mm day־¹ shell length and 0.074 g day־¹ body weight; this corresponds to 24.09 mm shell length and 27.01 g body weight increase per annum. Abalone fed on dried kelp grew at only 0.029 mm day־¹ shell length and of 0.021 g day־¹ body weight. Abalone grown on Abfeed® grew at 0.049 mm day־¹ shell length and 0.046 g day־¹ body weight which corresponds to 17.88 mm and 16.79 g increase per annum; this is better than the dried seaweed feeds, but poorer than the fresh seaweed combinations. This study shows that seaweed diets, particularly if the diets include seaweeds grown in animal aquaculture effluent, are good substitutes for the formulated feeds generally used today.
Scale insects on ericas : an apparently natural, unnoticeable threat to local biodiversity
(Botanical Society of South Africa, 2008) Maneveldt, Gavin
Introduction: An excursion into the Limietberg Nature Reserve in the Bain's Kloof Mountains during the winter of 2006, one that I have undertaken regularly over the past ten years or so, had revealed a noticeably high number of dead and apparently dying individuals of Erica species.
Is your garden green? How to be kind to your garden
(Botanical Society of South Africa, 2008) Maneveldt, Gavin
Years ago, there was plenty of open, natural veld surrounding our towns and it was rich in wildlife. As towns expanded the natural veld and wildlife shrank into patches between towns, factories and farm land. With this reduction in natural areas, suburban gardens now form an important place where wild animals can live and indigenous plants can flourish. There are many things that one can do to be an ‘environmentally friendly’ gardener.
How to write a popular article
(SANCOR, 2008) Maneveldt, Gavin; Moore, R.; Day, J.; Reid, J.
This newsletter has criteria for the development of a popular article.
A catalogue with keys to the non-geniculate coralline algae (Corallinales, Rhodophyta) of South Africa
(Elsevier, 2008) Maneveldt, Gavin; Keats, Derek; Chamberlain, Yvonne
Non-geniculate coralline red algae are common in all of the world’s oceans, where they often occupy close to 100% of the primary rocky substratum. The South African rocky subtidal and intertidal habitats in particular, are rich in diversity and abundance of non-geniculate coralline red algae. Despite their ubiquity, they are a poorly known and poorly understood group of marine organisms. Few scattered records of non-geniculate coralline red algae were published prior to 1993, but these should be treated with caution since many taxa have undergone major taxonomic review since then. Also, generic names such as Lithophyllum and Lithothamnion were loosely used by many authors for a host of different non-geniculate coralline algae. A series of taxonomic studies, based mainly on the Western Cape Province of South Africa, published particularly between 1993 and 2000, has significantly extended our knowledge of these algae from southern Africa. References to these latter papers and the older records are now gathered here and a list of the well delimited families (3), subfamilies (4), genera (17) and species (43) are presented. A catalogue with keys to the various taxonomic categories is also provided. A marked reduction in the number of real taxa has been found largely because many earlier recorded taxa have been reduced to synonymy, or have not been verified, or examined in a modern context and so their placement is considered dubious, particularly because the Corallinales have undergone major taxonomic revisions in recent years.

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