Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisor: K. Eric Wommack, Dept. of Plant & Soil Sciences. Includes bibliographical references.

Estuaries support productive and diverse ecosystems, based on the abundant food and diverse habitats. However with increasing human pressures, many estuaries along the coastline of Australia have become degraded. The primary objective of this study was to investigate the effects of estuarine metal contaminants on the physiology, and the subsequent accumulation, in the smooth toadfish, Tetractenos glaber, and their prey items in estuaries in the Sydney region, south eastern Australia. Toadfish and sediments were collected during three seasonal sampling periods (June 2002, September 2002 and January 2003) in four estuaries in the Sydney region (Port Hacking River, Cowan Creek, Parramatta River and Lake Macquarie). Sediment and toadfish tissue metal concentrations varied both spatially and temporally, with highest concentrations exhibited in the metal contaminated estuaries (Lake Macquarie and Parramatta River) during spring 2002 and summer 2003. Toadfish accumulated metals in different tissue, however field experiments were limited in determining the main pathways of accumulation. Controlled laboratory kinetic experiments using radioisotopes of 109Cd and 75Se, indicated that differences in the relative contributions of water and food in the accumulation of these metals are generally governed by the physiology of the toadfish and the type of prey eaten. The distribution of metals in fish organs is important for better understanding metal kinetics and their subsequent toxicity. Toadfish exposed to 109Cd in both water or food showed a shift in distribution from gut lining at the end of the uptake phase to the excretory organs, such as liver, by the end of the loss phase, suggesting that the main uptake pathway for water exposure was via the gut and not the gills, due to fish drinking large amounts of water to maintain osmoregulation. There was no appreciable shift in the distribution of 75Se from the uptake or loss phases, being mostly associated with the excretory organs (gills, liver and kidneys). Further investigation into the accumulation of metals in toadfish prey items revealed that differences in uptake and loss of 109Cd and 75Se were influenced by their aqueous speciation, as well as differences in animal physiology, sequestration, storage and excitation mechanisms. The uptake rates and CFs of 109Cd and 75Se were highest, and the biological half-lives the longest, in pygmy mussels, ghost shrimps and polychaetes relative to the semaphore and soldier crabs. Elevated metal concentrations in certain toadfish tissues from the four estuaries were linked to reduced lipid concentrations and increased protein concentrations, which may be detrimental for growth, reproductive output and survivorship of the fish. A closer investigation into the nutritional value and metal concentrations of toadfish prey items in a selected metal contaminated estuary (Parramatta River) revealed that toadfish from the more contaminated sites within the estuary may grow faster due to higher nutritional value of prey items on a local scale, however on a larger spatial scale, this was not evident. Further investigation is required to determine whether larger toadfish size can be attributed to physiological acclimation or genetic resistance through generations of continuous metal exposure. Many studies have assessed metal concentrations in water, sediments and biota in the field, however few studies have combined both field and laboratory experiments to examine the effects of metals on fish physiology and reproduction, and metal transfer pathways in aquatic biota. This study has contributed to a better understanding of metal accumulation and its physiological effects in estuarine biota and highlights the high spatial and temporal variability in responses of organisms to environmental metal pollution.

Estuaries support productive and diverse ecosystems, based on the abundant food and diverse habitats. However with increasing human pressures, many estuaries along the coastline of Australia have become degraded. The primary objective of this study was to investigate the effects of estuarine metal contaminants on the physiology, and the subsequent accumulation, in the smooth toadfish, Tetractenos glaber, and their prey items in estuaries in the Sydney region, south eastern Australia. Toadfish and sediments were collected during three seasonal sampling periods (June 2002, September 2002 and January 2003) in four estuaries in the Sydney region (Port Hacking River, Cowan Creek, Parramatta River and Lake Macquarie). Sediment and toadfish tissue metal concentrations varied both spatially and temporally, with highest concentrations exhibited in the metal contaminated estuaries (Lake Macquarie and Parramatta River) during spring 2002 and summer 2003. Toadfish accumulated metals in different tissue, however field experiments were limited in determining the main pathways of accumulation. Controlled laboratory kinetic experiments using radioisotopes of 109Cd and 75Se, indicated that differences in the relative contributions of water and food in the accumulation of these metals are generally governed by the physiology of the toadfish and the type of prey eaten. The distribution of metals in fish organs is important for better understanding metal kinetics and their subsequent toxicity. Toadfish exposed to 109Cd in both water or food showed a shift in distribution from gut lining at the end of the uptake phase to the excretory organs, such as liver, by the end of the loss phase, suggesting that the main uptake pathway for water exposure was via the gut and not the gills, due to fish drinking large amounts of water to maintain osmoregulation. There was no appreciable shift in the distribution of 75Se from the uptake or loss phases, being mostly associated with the excretory organs (gills, liver and kidneys). Further investigation into the accumulation of metals in toadfish prey items revealed that differences in uptake and loss of 109Cd and 75Se were influenced by their aqueous speciation, as well as differences in animal physiology, sequestration, storage and excitation mechanisms. The uptake rates and CFs of 109Cd and 75Se were highest, and the biological half-lives the longest, in pygmy mussels, ghost shrimps and polychaetes relative to the semaphore and soldier crabs. Elevated metal concentrations in certain toadfish tissues from the four estuaries were linked to reduced lipid concentrations and increased protein concentrations, which may be detrimental for growth, reproductive output and survivorship of the fish. A closer investigation into the nutritional value and metal concentrations of toadfish prey items in a selected metal contaminated estuary (Parramatta River) revealed that toadfish from the more contaminated sites within the estuary may grow faster due to higher nutritional value of prey items on a local scale, however on a larger spatial scale, this was not evident. Further investigation is required to determine whether larger toadfish size can be attributed to physiological acclimation or genetic resistance through generations of continuous metal exposure. Many studies have assessed metal concentrations in water, sediments and biota in the field, however few studies have combined both field and laboratory experiments to examine the effects of metals on fish physiology and reproduction, and metal transfer pathways in aquatic biota. This study has contributed to a better understanding of metal accumulation and its physiological effects in estuarine biota and highlights the high spatial and temporal variability in responses of organisms to environmental metal pollution.

Estuaries support productive and diverse ecosystems, based on the abundant food and diverse habitats. However with increasing human pressures, many estuaries along the coastline of Australia have become degraded. The primary objective of this study was to investigate the effects of estuarine metal contaminants on the physiology, and the subsequent accumulation, in the smooth toadfish, Tetractenos glaber, and their prey items in estuaries in the Sydney region, south eastern Australia. Toadfish and sediments were collected during three seasonal sampling periods (June 2002, September 2002 and January 2003) in four estuaries in the Sydney region (Port Hacking River, Cowan Creek, Parramatta River and Lake Macquarie). Sediment and toadfish tissue metal concentrations varied both spatially and temporally, with highest concentrations exhibited in the metal contaminated estuaries (Lake Macquarie and Parramatta River) during spring 2002 and summer 2003. Toadfish accumulated metals in different tissue, however field experiments were limited in determining the main pathways of accumulation. Controlled laboratory kinetic experiments using radioisotopes of 109Cd and 75Se, indicated that differences in the relative contributions of water and food in the accumulation of these metals are generally governed by the physiology of the toadfish and the type of prey eaten. The distribution of metals in fish organs is important for better understanding metal kinetics and their subsequent toxicity. Toadfish exposed to 109Cd in both water or food showed a shift in distribution from gut lining at the end of the uptake phase to the excretory organs, such as liver, by the end of the loss phase, suggesting that the main uptake pathway for water exposure was via the gut and not the gills, due to fish drinking large amounts of water to maintain osmoregulation. There was no appreciable shift in the distribution of 75Se from the uptake or loss phases, being mostly associated with the excretory organs (gills, liver and kidneys). Further investigation into the accumulation of metals in toadfish prey items revealed that differences in uptake and loss of 109Cd and 75Se were influenced by their aqueous speciation, as well as differences in animal physiology, sequestration, storage and excitation mechanisms. The uptake rates and CFs of 109Cd and 75Se were highest, and the biological half-lives the longest, in pygmy mussels, ghost shrimps and polychaetes relative to the semaphore and soldier crabs. Elevated metal concentrations in certain toadfish tissues from the four estuaries were linked to reduced lipid concentrations and increased protein concentrations, which may be detrimental for growth, reproductive output and survivorship of the fish. A closer investigation into the nutritional value and metal concentrations of toadfish prey items in a selected metal contaminated estuary (Parramatta River) revealed that toadfish from the more contaminated sites within the estuary may grow faster due to higher nutritional value of prey items on a local scale, however on a larger spatial scale, this was not evident. Further investigation is required to determine whether larger toadfish size can be attributed to physiological acclimation or genetic resistance through generations of continuous metal exposure. Many studies have assessed metal concentrations in water, sediments and biota in the field, however few studies have combined both field and laboratory experiments to examine the effects of metals on fish physiology and reproduction, and metal transfer pathways in aquatic biota. This study has contributed to a better understanding of metal accumulation and its physiological effects in estuarine biota and highlights the high spatial and temporal variability in responses of organisms to environmental metal pollution.

Thesis (Ph.D. (Zoology & Entomology)) - Rhodes University, 2009.

Thesis (Ph. D.) - L'Université de Clermont II (U.E.R. Sciences exactes et naturelles à dominante recherche), 1978. / At head of title: Série : E ; No. d'ordre : 260.

The primary production of Spartina maritima, the dominant macrophyte of the intertidal salt marshes of the Swartkops estuary, was determined for inclusion into the proposed ecosystem model. Several methods for measuring net production devised for North temperate Spartina species were used, as no single method was considered reliable for the local species. In addition, a new method was devised to take into account the aseasonal growth behaviour of S. maritima . Most energy for growth appears to be directed into leaf production, rather than shoot growth. Live net production values were 523-680 g m⁻²‚ yr ⁻¹, which are generally lower than estimates of N. American Spartina species. Total Live production of S. maritima for the whole Swartkops estuary was 495,6 x I0³kg yr ⁻¹, which is an estimation of potential food resources. Formation of S. maritima detritus by decomposition was significantly related to air and water temperatures. Thus detritus production showed a wide seasonal variation about a mean of 374 g m⁻² yr⁻¹. The total S. maritima detritus production of 307,5 x I0³kg for the whole Swartkops estuary was determined as an estimate of available food resources. Export of detrital material from Spartina marshes to estuarine waters was negligible. Even during a maximal Equinoctial tide, only 6,26 dry g m⁻² detritus was exported from the creek catchment area of Spartina stands. This study has shown that concepts evolved for North temperate estuaries should be carefully considered before being applied to local situations, particularly in view of the relatively low, aseasonal production of S. maritima and the negligible contribution of its detritus to estuarine waters. Furthermore, it is essential that utilisation of primary production by secondary producers be determined before the function of the estuarine ecosystem may be understood

The abundance and microspatial distribution of harpacticoid copepods were studied from Jan 1977 to Jan 1980 at two intertidal sites on the Fraser River Delta, B.C.: one (Sand) on the crest of a sand wave and the other (Mud) on the edge of its muddy trough. Eight species formed the communities at the two sites. The composition of the communities was studied by biweekly survey in 1978. Longer term changes in the organization of the sand community were followed by annual mid-winter surveys over four years. Factor analysis was used to group species with similar patterns of seasonal occurrence and macrohabitat distributions. Microspatial patterns in the two communities were compared by heterogeneity chi-square analysis from random core samples collected monthly. The distribution of species relative to small-scale hydraulic bedforms (sand ripples) was studied at the sand site. Distinct patterns of community organization were seen at the two sites. The mud community was characterized by high temporal overlap of species; the sand species showed a distinctive pattern of temporal segregation. Although species in both communities were segregated at small spatial scales, microspatial partitioning was stronger and seasonally more variable in the mud. Spatial patterns in the sand were related to the rippled bedforms. Biogenic structuring by macrobenthos and disturbance by predators were implicated as the causes of microspatial patterns observed in the mud community in summer. Although the two communities showed distinct features of organization they were not completely isolated. Two mud species, Scottolana canadensis and Tachidius triangularis, 'migrated' to the sand in summer. The role of biological interactions in structuring the communities was investigated. Predation by small tidepool fish, Clevelandia ios and Leptocottus armatus, was studied by gut analysis. Predation was species- and size-selective, with two epipelic species, S. canadensis and T. triangularis, occurring most frequently in fish gut samples. A morphometric basis for ontogenetic variation in predation by C. ios was proposed. Evidence to support the hypothesis that competitive interactions help to structure harpacticoid copepod communities was found in changing patterns of abundance, changing patterns of microhabitat use and morphometric character displacement over four years. Competitive interactions were highly dynamic and appeared to be part of the cause of both the temporal and microspatial segregation observed in the sand community in 1979. By 1980, the eight species present in the January sand community formed a displacement series in body sizes. Although each harpacticoid community is unique, numerous parallels exist between the structure and function of the Iona North assemblage and those from shallow water habitats, worldwide. It is clear, therefore, that the conclusions from this research have more than local significance. / Science, Faculty of / Zoology, Department of / Graduate

1. The development of estuarine research in South Africa has been reviewed, and the present state of knowledge assessed. Little is known about many abundant estuarine species, and a previously unstudied prosobranch Nassarius kraussianus (Dunker), was selected for investigation. 2. The study area, a mudflat on the Bushmans River estuary, was divided into three habitat types: supratidal, intertidal and subtidal, each with a particular substratum and pattern of vegetation cover. The distribution of N. kraussianus is associated with the nature of the substratum and the degree of Zostera capensis Setchell cover. 3. A brief review of pertinent literature indicated the necessity of relating population parameters to environmental conditions. 4. The population biology of N. . kraussianus was investigated, and the size frequencies, sex ratios, and male/female size frequencies were recorded over three distinct periods: pre-flood, post-flood and recovery. 5. The Bushmans River flooded in July and August 1979, and the results of the flood have been described. The most immediate result was a period of low salinity, but the most persistant result was the deposition of silt, which had an important effect on the substratum and the Z. capensis beds. 6. The pre-flood population was characterised by patchy distribution, and by a large number of mature adults in relation to juveniles. Females were generally larger than males, and the sex ratio was 1:1. The presence of juveniles in consistantly low numbers indicated that reproduction may have been continuous, but that intraspecific adult/juvenile competition may have kept juvenile numbers low. 7. The post-flood period was characterised by extreme physical conditions, and the survival of a few adults. Juveniles were completely annihilated, and were absent until a few were spawned by the surviving adults towards the end of 1979 . Sex ratio was biased, and females predominated. 8. The recovery period began abruptly with the arrival of a large number of juveniles in the 2, 3 and 4 mm size classes. Recolonisation coincided with habitat recovery, and reqeneration of the Z. capensis cover. Recolonising juveniles grew quickly, reaching adult size in three months. After that, juveniles were spawned on the mudflat by the new population. During this period the sex ratio did not return to the pre-flood 1:1, but remained female biased. Males and females grew at the same rate over the period measured, but females were consistantly larger, indicating that at some stage female growth may be faster. 9. The recolonising juveniles arrived in a regenerated habitat, at a time when temperatures were high, and conditions for growth probably optimal. If intraspecific competition was a feature of the pre-flood population it would have been elimianted in the recovery phase, by the absence of adults. 10. N. kraussianus is apparently omnivorous and proabably not food limited. However, carrion, a limited resource, may be essential for growth to reproductive maturity. Adults and juveniles may compete for this resource, and any juveniles deprived of access to carrion may be stimulated to leave the parental habitat. 11. N. kraussianus is ovoviviparous, and carries up to 5 egg cases within the uterus. Each triangular egg case contains 1 egg which hatches after approximately 3 weeks, as a free swimming veliger. Yeligers metamorphose, and settle after 4-7 days, assuming a benthic mode of life. Ovoviviparity protects the developing embryo from the rigours of environmental extremes, and ensures that embryos are not swept out to sea . Additionally, veligers have a high probability of settling in the parental habitat. 12. This reproductive strategy has been compared with other prosobranchs, and the evolutionary trends within the Prosobranchia, and particularly the Nassariidae, have been related to their dispersal potential. 13. Developmental strategy is intimately related to recolonisation potential. Ovoviviparity, and the lack of pelagic larvae, did not limit the recolonisation potential of N. kraussianus, and recolonisation was probably effected by post-larval juveniles, which may disperse from neighbouring estuaries and coastal pools, by floating in coastal and tidal currents. Post-larval juveniles have two important advantages over larvae. They are less vulnerable to physical extremes, and they have a sturdy crennellated shell which probably affords them protection from predators. 14. Examples of larval recolonisation in estuarine populations have been reviewed, and the most fundamental conclusion of this work is that recolonisation is an important, and probably widespread, adaptation to estuarine conditions in South Africa.

The distribution of Callianassa kraussi in southern Africa extends from Lamberts Bay on the west coast to San Martinho in Mocambique. This represents a northerly extension of the range from the previous known limit of Inhaca Island. In this area 59 localities were visited and records obtained for an additional 16. Three areas were selected for detailed study. These were the west Kleinemonde estuary, which is normally closed off from the sea by a sand bar and the open Swartkops estuary both on the southeastern Cape coast, and the Swartvlei system, which consists of a lake connected to the sea by a channel which closes intermittently, on the southern Cape coast. The nature of the burrows constructed by C. kraussi was investigated in these areas. Burrow complexes may have up to nine entrances but more commonly two to four. Laboratory studies suggest that the number of entrances does not exceed the number of prawns present and consequently burrow opening counts will give an estimate of population density. Water movement can result in the closing off of burrows while strong water and sand movement will exclude C.kraussi from an area. C.kraussi is also excluded from areas which have very coarse substrates. A three year regular sampling program showed that C.kraussi breeds mainly in winter/spring with a smaller breeding peak in summer. Egg development time at 20°C in a salinity of 35° /₀₀ is 30-33 days. There are two larval stages which last 3-5 days. Development time of the eggs is tripled at temperatures of 13-15°C while larval development time is extended to 9-14 days. Development is possibly slightly accelerated at 25 ± 3°C but the number of eggs hatching is markedly reduced. Larval development times were similar to those at 20° and 35°/₀₀. There are no planktonic larval stages. Growth was more rapid and greater size was attained in the open Swartkops estuary than in the closed Kleinemonde estuary. Prawns hatching in winter/spring breed for the first time in the following summer at an age of about 16 months and then again in the following winter/spring at an age of about 2 years. Prawns hatching in summer breed in the following winter at an age of about 18 months and then again in the immediately following summer. Longevity in both sexes is about 2 years. Dispersal is accomplished by migration of the post-larval juvenile phases at an age of 3-5 months. Non-selfmaintaining populations exist in areas where salinities are too low to permit breeding. Population densities were found to vary markedly in different areas. Investigations of osmotic and ionic regulation showed that C.kraussi is a strong hyper-regulator and thus distinct from any other known species in the genus. Volume regulatory ability is well developed and depends on variable rates of urine production. Salt loss in dilutions occurs almost equally via the gills and the urine. The general responses of C.kraussi to dilutions of sea water are discussed. Various suggestions for conservation measures based on the distribution and iife cycle of C.kraussi were made. The factors affecting the distribution of C.kraussi are discussed. The problem of the larval development in C.kraussi was discussed in relation to reviews of larval types of benthic invertebrates. The importance of the burrow, the possible route by which C.kraussi has invaded estuaries and the differences between open and closed estuaries as shown by the effects on C.kraussi were discussed.