Compared to natural forests, fast-growing plantations of exotic species such as Pinus radiata are often perceived as marginal habitat or unsuitable habitat for most native species. By studying Coleoptera (beetles) in a variety of landscape elements (pasture, native forest and different aged Pinus radiata stands) in a highly modified and fragmented landscape in New Zealand I aimed to determine the value of exotic plantation forests for native biodiversity, and how these species are affected by different sized clearfell harvest areas. Pitfall trap sampling of beetles showed that plantation forest stands can provide suitable complimentary habitat to native forest for many species. Rarefied species richness of Carabidae, Scarabaeidae and Scolytinae was not significantly different between habitats, however, habitat types differed significantly in their beetle community composition. Comparing different production habitats, Pinus radiata stands had a beetle community composition most similar to native forest. However, a small minority of species, e.g., Dichrochile maura, were restricted to native forest habitat highlighting the importance of retaining indigenous ecosystems within plantations. Unlike human modified habitats, native forests did not provide suitable habitat for exotic species. Clearfell harvesting is controversial and its impact on biodiversity is a key constraint for many forest certification programs, such as that administered by the Forest Stewardship Council (FSC). Despite this, no replicated manipulative experimental studies of the impact of different sized clearfell harvest areas on biodiversity have been undertaken at scales relevant to the New Zealand forest industry. One potential model of the impact of different clearfell harvest sizes is the concept of a threshold size. A threshold scenario may occur where clearfell harvest impacts increase at a rate disproportionate to the change in clearfell size over a small range of harvest areas, but impacts remain relatively unchanged either side of the threshold zone. I sampled Coleoptera in experimentally created 0.01, 0.05, 0.5, 5.0, 50 and 500 ha clearfells within Pinus radiata plantations in the central North Island of New Zealand. The wide range of clearfell harvest sizes, including some very small areas, such as 0.01 ha was instigated in an attempt to document potential clearfell harvest size thresholds. Rarefied native beetle species richness was higher in harvest areas compared to adjacent mature plantation stands. The beetle species richness in 5 ha and 500 ha harvest areas was significantly greater species than that in small 0.01 - 0.5 ha harvest areas. Although, the high beetle diversity recorded in 500 ha clearfells should be treated with caution due to confounding spatial autocorrelation. The degree of change in beetle community composition increased with increasing clearfell harvest area. Beetle assemblages in large harvest areas were less similar to their paired adjacent mature forest than smaller harvest areas. Although, constrained multivariate ordination techniques did show a short-term change in beetle species composition between recently clearfelled harvest areas of as little as 0.05 ha and adjacent mature P. radiata stands. The colonisation by open-habitat disturbance-adapted species was a key driver of this change, some species dispersed into clearfelled stands in significant densities within days post-harvest. Overall, there were no distinct short-term trends to the change in species richness as a function of increasing harvest area that would suggest an ecological impact threshold response. If short-term outcomes of clearfell harvesting are ameliorated by successful recolonisation, the long-term spatial arrangement of different aged stands becomes more important for the maintenance of biodiversity at the landscape level than short-term consequences of harvesting. By sampling selected beetle taxa in 1, 2, 4, 8, 16 and 26 year-old stands, I found that the abundance of seven out of eight of the species selected for analysis recovered to levels similar to those in adjacent mature forest within the timeframe of a single harvest rotation. Individual species utilised different aged stands, indicating different life-history strategies. For example, open-habitat, disturbance-adapted species such as Cicindela tuberculata and Sitona discoideus were prominent in young stands, and forest species such as Pycnomerus sophorae and Paracatops phyllobius were highly abundant in older stands. These alternative life-history strategies highlight the benefits of maintaining a mixture of different aged stands to increase biodiversity at the landscape level. This thesis fills an important gap in our knowledge of biodiversity in production landscapes. I show that plantation forests have value as complimentary habitat to native forest and they make an important contribution to the maintenance of biodiversity at the landscape level. Although clearfell harvesting is a severe disturbance to the forest ecosystem, the long-term recovery of beetle populations suggests that harvesting is not the key limiting factor to the enhancement of biodiversity in the plantation forests studied. This unusual situation is possibly the result of prior land-use history, as many plantations were established on degraded pastoral land, and harvest-sensitive species are unlikely to have survived this initial land-use change. As such, the severity of the long-term impacts of clearfell harvesting on biodiversity are likely to be context specific and will vary accordingly. The importance of spatial heterogeneity of habitat elements, including different aged plantation stands and native forest remnants, needs to be investigated in more detail to determine what limits biodiversity in this plantation landscape. Key points to consider are the proximity to, and proportion of, native forest cover in the landscape and the degree of connectivity among native remnants. It is these landscape-level attributes that may determine biodiversity at a regional scale, and more emphasis should be placed on landscape scale factors and there interaction with stand specific forest management practices. For example, the spatial mosaic of harvesting areas may need to be of a finer-scale when there are fewer native remnants within the landscape.

The potential relationship between riparian arachnids and aquatic insect productivity was assessed in forest streams throughout the central South Island of New Zealand. Initially, a survey was conducted of thirty seven, first-third order forest streams. Streams were selected to represent a range of benthic invertebrate standing crops (as a surrogate measure of "productivity") from Banks Peninsula streams with relatively high benthic invertebrate densities to acid mine drainage streams near Reefton that were almost devoid of aquatic life. At each site benthic invertebrate densities and biomass were measured in riffle habitats and adjacent gravel bars were sampled for terrestrial invertebrates. At a sub-set of 16 sites, a 20 metre longitudinal web-building spider survey was conducted along each bank of the stream. As an additional component, a 20 metre transect starting at the stream margin and running perpendicularly into the forest was used to survey the density of web-building spiders with increasing distance from the stream. Results from the survey of in-situ stream insect biomass and gravel bar invertebrates showed a strong relationship between aquatic insect biomass and the biomass of riparian arachnids (R2 = 0.42, P < 0.001) having accounted for potentially confounding factors such as stream size, elevation, substrate and disturbance. The 20 metre longitudinal survey showed that streams with the highest in-situ insect biomass had significantly higher densities of web-building spiders along their banks (R2 = 0.28, P < 0.05), having accounted for potential confounding variables of elevation, habitat architecture and stream and channel width. The stream to forest survey showed a strong exponential decay in web-building spider densities with increasing distance from the stream (R2 = 0.96, P < 0.0001). Regardless of stream productivity web-building spiders were most abundant at the stream margins and rapidly declined to very low densities 20 metres from the stream. In order to further test the relationship between riparian web-building spider densities and stream insect productivity, a stream fertilization experiment was conducted on six first-second order streams in the Maimai experimental catchment, Reefton. Three streams were enriched by the addition of a fertiliser solution mainly consisting of sodium nitrate for seven months, and the other three streams were used as controls. Water chemistry, benthic invertebrate communities, emerging aquatic adults, and the densities of web-building spiders along the stream corridor and in the forest were monitored in three seasons (spring, summer and autumn) over the course of the nutrient-addition. By the end of the experiment, conductivity was significantly higher in nutrient-addition streams than in the control streams (F = 80.5, P < 0.001), but chlorophyll concentrations showed no significant differences between treatments. Both benthic mayfly densities (F = 6.15, P < 0.05) and the biomass of adult aquatic dipterans (Chironomidae, Simuliidae) (F = 9.25, P < 0.01) were significantly higher in nutrient-addition streams in the last sampling round. Spiders recorded from intercept traps indicated that by the end of the experiment spider activity was significantly higher within 2.5 metres of the nutrient-addition streams (F = 5.70, P < 0.01). However, seasonal densities of web-building spiders along the stream margin and in the forest decreased with no significant differences observed between nutrient-addition and control streams. The results from these studies indicate that adult insects emerging from streams represent an important source of prey that could influence the biomass and abundance of riparian arachnids. Additionally, the results imply that stream productivity and size could mediate the strength of the interaction between riparian and stream habitats. Moreover, feedback mechanisms present in both systems could have implications for such interactions. The elevated densities of web-building spiders observed at the stream margin led to the proposal of the "Highway Robber" hypothesis. This hypothesis suggests that such higher densities of spiders are the result of increased insect activity along the stream corridor: the emergence of adult aquatic insects was predicted to vary less over temporal and spatial scales than that of terrestrial insects due to the poorly synchronized life histories in many New Zealand stream insects. I conclude by suggesting that there are numerous anthropocentric perturbations such as loss of heterogeneity, introduced species, pollution and habitat degradation that could undermine and decouple the intimate linkages between aquatic and terrestrial ecosystems.

Aravaipa Creek is one of the few, small, permanent desert streams in Arizona. It has diverse fish and invertebrate faunas but the invertebrates are not well-known. I collected benthic and 24 hr. drift samples there during 1980-1981 and found 31 taxa. The most abundant species were Baetis insignificans and Choroterpes inornata (Ephemeroptera), which exhibited the nocturnal drift periodicity characteristic of drifting invertebrates studied elsewhere. In the laboratory, observations of the drifting behaviors of five species of mayflies were made in 5 and 10 cm/s current speeds. These provided evidence that drifting insects are not necessarily swept away by the current (accidental drift), but are probably exhibiting a specific behavior triggered by local conditions such as lack of cover or food (active drift). I also tested the relationship between drift rates and the presence and absence of food (periphyton) using B. insignificans and C. inornata. With both species, the number of insects drifting increased significantly when periphyton was not present; therefore lack of food may be an important cause of drift. The sizes of the nymphs used in these experiments were determined; I found that drifters were either similar in size to non-drifters (C. inornata), or that drifters were larger than nymphs that did not drift (B. insignificans). These results suggest that direct competition by size does not play a role in determining which individuals drift. Drifting appears to be a dispersal mechanism for benthic invertebrates; it maintains the numbers and distribution of the benthos according to the rapidly changing distribution of their food resources which occurs in streams. This process fits some recent models of population regulation by dispersal.

Data for a study of the benthic macroinvertebrates in Imperial Reservoir in Yuma County, Arizona was collected 1970-1973. Imperial Reservoir is an old, heavily sedimented reservoir on the lower Colorado River. An extensive dredging program revealed that the benthic habitat supported a low number of invertebrate species (four insects and two oligochaets) in comparison to other bodies of water. Probable reasons for the low number of species included high salinity, low organic detrital input into the reservoir, low habitat and substrate diversity, temporary low dissolved oxygen concentration, possible contamination with agricultural chemicals, and the remoteness of Imperial Reservoir from other aquatic environments. Within Imperial Reservoir the benthic macroinvertebrate community was restricted to more isolated, calm, side lakes which altogether made up only 23% of the entire surface area of the reservoir. Within these side lakes benthic macroinvertebrates were found primarily on mud substrate. Invertebrates were not found beneath dense stands of Najas marina, a rooted submersed macrophyte. Only two species of invertebrates appear to inhabit rocky substrates. Community analysis suggested that there were no large differences among most habitats where benthic invertebrates were found. A study of the microdistribution of each species of invertebrate indicated that there were two patterns of spatial dispersion: (1) taxa which bred continuously appeared to have no life history related change in dispersion; and (2) taxa which formed recognizable cohorts appeared to spread out from initial egg mass and dispersion changed with time from clumped to random. Secondary net production measures were made directly on predominant benthic invertebrates at two sites in Imperial Reservoir. Both sites had similar production values which were low when compared to production values from other bodies of water. Low benthic production in Imperial Reservoir was related to several environmental factors including high water temperature and temporary low oxygen concentration near the bottom during the summer, low input of organic detritus into the reservoir, and high predation on benthic invertebrates by fish. Collection and analysis of the stomach contents of the bass, bluegill and redear sunfish revealed that the smaller fish of a species were more dependent on benthic invertebrates for food. Large bass did not use benthic invertebrates as heavily as either bluegill or redear.

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: To predict the influence of temperature increases on organisms, and their capacity to respond to climate change, information on the upper thermal tolerance of organisms and its plasticity is required. However, various factors, such as rate of temperature change, may influence basal thermal tolerance and plastic responses, and consequently the vulnerability of organisms to temperature change. Although slower rates of temperature change might be more ecologically relevant, the majority of thermal tolerance studies feature rates of temperature change that are faster than those experienced by organisms in nature. Additionally, studies using slower rates of temperature change have been criticized as factors such as changes in body condition and accumulation of stress over time may confound results. This study determined the influence of fast and slow rates of temperature change and plasticity, induced by acclimation to different temperature conditions for 5 – 15 days, on the upper thermal tolerance of marine amphipod and isopod species from sub-Antarctic Marion Island and South Africa. Using congeners, intra- and inter-specific comparisons of the upper thermal tolerance and plasticity of these organisms were made across geographical regions (South Africa vs. Marion Island), across sites within regions (West coast vs. South coast of South Africa) and between tidal zones. Overall, lower rates of temperature change were found to be associated with lower values of upper thermal tolerance. At fast rates of temperature change, acclimation at high temperatures was associated with an increase in thermal tolerance, whereas at slow rates, acclimation to higher temperatures either had no effect or caused a decrease in thermal tolerance. Furthermore, microclimate recordings suggest that these organisms likely experience rates of temperature increase that are intermediate between the fast and slow rates employed in this study. Thus, in nature these marine invertebrates have upper thermal tolerances that are higher than mean environmental temperature and can likely mount plastic responses during short-term temperature variation. At slow rates of temperature change, however, the upper thermal tolerance of these organisms approximates environmental temperature and plasticity is reduced, likely increasing vulnerability to high temperatures. At the intra-specific level, upper thermal tolerance and plasticity response varied based on mass and sex, however, these effects were species-specific. Isopods inhabiting cooler but more variable microsites on the West coast of South Africa had a higher upper thermal tolerance, but similar magnitude of plasticity, than a population of the same species from the warmer, less variable South coast. Generally, Marion Island species had a lower upper thermal tolerance but higher magnitude of plasticity than South African species. The variability reported here at different hierarchical and geographical scales could be linked to the distinct thermal environments experienced, and the differing physiological and behavioural responses of populations and species to their thermal environments. This variation in thermal tolerance might be critical during environmental change and suggests that species composition may be altered in the future. / AFRIKAANSE OPSOMMING: Om die invloed van temperatuur verhogings op organismes, en hul vermoë om te reageer op hierdie verandering, te voorspel, word inligting oor hoë temperatuur verdraagsaamheid van organismes en die plastisiteit hiervan, benodig. Verskeie faktore, soos die tempo van verandering, kan egter basale termiese verdraagsaamheid en plastiese reaksies beïnvloed. Dus, mag dit die tasbaarheid vir temperatuur verandering beïnvloed. Alhoewel stadiger tempo van verandering meer ekologies relevant kan wees, fokus die meerderheid van warm verdraagsaamheid studies op temperatuur veranderinge wat vinniger gebeur as wat ervaar word deur organismes in die natuur. Boonop word studies wat fokus op stadige veranderinge in temperatuur, gekritiseer omdat faktore soos ‘n verandering in liggaamstoestand en die opeenhoping van stres, potentieël die resultate kan belemmer. Hierdie studie ondersoek die invloed van vinnige en stadige temperatuur veranderinge en die plastisiteit, geïnduseer deur akklimasie, met betrekking tot verskeie temperature vir 5-15 dae. Ons fokus spesifiek op die hoë temperatuur verdraagsaamheid van mariene amphipod- en isopod spesies van sub-Antarktiese Marion Island en Suid Afrika. Deur gebruik te maak van spesies wat aan dieselfde genus behoort, is vergelykings getrek tussen intra- en inter-spesies verbande met betrekking tot hul termiese verdraagsaamheid en plastisiteit. Die studie is oor geografiese streke (Suid Afrika vs. Marion Island), tussen areas binne ‘n geografiese streek (Weskus vs. Suidkus van Suid Afrika) en tussen gety sones voltooi. Oor die algemeen was stadige temperatuur veranderinge geassosieër met ‘n laer termiese verdraagsaamheid vir hoë temperature. Met vinnige veranderinge in klimaat, was akklimasie by hoë temperature geassosieër met ‘n hoër temperatuur limiet, maar by stadige temperatuur veranderinge het akklimasie by hoë temperature geen effek gehad nie, of het ‘n afname in termiese verdraagsaamheid veroorsaak. Verder het mikroklimaat opnames aangedui dat hierdie organismes waarskynlik temperatuur verhogings ondervind in hul natuurlike habitat, wat intermediêre is van die vinnige en stadige veranderinge wat in hierdie studie gebruik is. Dus, in die natuur, het hierdie mariene invertebrate `n boonste termiese toleransies wat hoër is as die gemiddelde omgewingstemperatuur en kan hulle waarskynlik van platiese reaksies gebruik maak tydens kort-termyn temperatuur variasie. Gedurende stadige temperatuur veranderinge toon hulle alhoewel hoë termiese verdraagsaamheid teenoor die omgewingstemperature en plastisiteit is verminder, wat heel waarskynlik toenemende kwesbaarheid vir hoë temperature tot gevolg het. Op die intra-spesifieke vlak was wisseling in hoë termiese verdraagsaamheid gebaseer op liggaams massa en geslag, maar hierdie veskille was spesie-spesifiek. Isopoda wat koeler areas bewoon, met meer variasie in hul mikroklimaat, soos ondervind in die Weskus van Suid Afrika, het `n hoër termiese verdraagsaamheid. Maar, soortgelyke mate van plastisiteit, as 'n populasie van dieselfde spesie van die warmer, minder veranderlike Suidkus. Oor die algemeen het Marion-eiland spesies 'n laer termiese verdraagsaamheid, maar hoër grootte van plastisiteit as Suid-Afrikaanse spesies. Die veranderlikheid wat hier geraporteer is, kan op verskeie hiërargiese en geografiese vlakke gekoppel wees aan die unieke termiese omgewings wat hierdie organismes ervaar en aan die verskillende fisiologiese- en gedrags reaksies van populasies en spesies tot hulle termiese omgewings. Die variasie in termiese verdraagsaamheid kan krities wees tydens omgewingsverandering en dui daarop dat spesie-samestelling kan verander in die toekoms. / The British Antarctic Survey for funding

1. Realigning rivers is becoming common as a solution to conflicting needs of land development and ecosystem preservation. Although an increasing number of projects are monitored, exactly how these channels develop as functional stream ecosystems is still poorly understood. Mining in the upper catchment of the River Nith (Scotland) required the realignment of 3km (approx.) of river. The engineered channel was designed around sound geomorphological principles of sediment transport and supply with a sinuous planform and pool-riffle sequences along the installed gravel-bed. 2. A comprehensive survey covering biotic and abiotic development was devised and implemented to test models and hypotheses relating to the development riverine habitats over the first three years. 2. Physical habitat development at the reach scale was investigated using fixed-point photography and differential GPS surveys of the thalweg and of cross-sectional form every 100m. This revealed the development of a relatively diverse streambed habitat in response to both the channel slope and planform. However, other than at meander bends where asymmetry developed over several years, little change was observed to the form of the engineered riverbanks. 3. Kick-net surveys of benthic invertebrate communities at 10 sites showed a negative relationship between specific measures of diversity and downstream distance during the early stages of development. (e.g. Richness with chainage at the 6 month stage) but the relationship degrades rapidly and is likely in part to appear as a result of low population densities. 4. Survey of transects through the riparian zone perpendicular to the river indicated that colonisation by vegetation is also related to distance along the realignment but physical habitat and geographical factors play a more dominant role over development (Canonical correspondence analysis of vegetation data in 2007) 5. Many of the indices of diversity for both biotic and abiotic elements of the ecosystem proved ineffective at detecting development at the reach scale. This may be because significant changes occur at a smaller scale than was detected by the surveys. It is likely that greater resolution is required to detect more ecologically meaningful relationships and patterns. 6. Overall study shows constructed realignments can rapidly develop a diverse streambed community within 24 months. Riparian communities are slower to develop because of the slow development of riverbank habitat diversity. Other ecosystem properties such as resilience and connectivity may take much longer.

<p>The evolution of reproductive strategies involves a complex calculus of costs and benefits to both parents and offspring. Many marine animals produce embryos packaged in tough egg capsules or gelatinous egg masses attached to benthic surfaces. While these egg structures can protect against environmental stresses, the packaging is energetically costly for parents to produce. In this series of studies, I examined a variety of ecological factors affecting the evolution of benthic development as a life history strategy. I used marine gastropods as my model system because they are incredibly diverse and abundant worldwide, and they exhibit a variety of reproductive and developmental strategies. </p><p>The first study examines predation on benthic egg masses. I investigated: 1) behavioral mechanisms of predation when embryos are targeted (rather than the whole egg mass); 2) the specific role of gelatinous matrix in predation. I hypothesized that gelatinous matrix does not facilitate predation. One study system was the sea slug Olea hansineensis, an obligate egg mass predator, feeding on the sea slug Haminoea vesicula. Olea fed intensely and efficiently on individual Haminoea embryos inside egg masses but showed no response to live embryos removed from gel, suggesting that gelatinous matrix enables predation. This may be due to mechanical support of the feeding predator by the matrix. However, Haminoea egg masses outnumber Olea by two orders of magnitude in the field, and each egg mass can contain many tens of thousands of embryos, so predation pressure on individuals is likely not strong. The second system involved the snail Nassarius vibex, a non-obligate egg mass predator, feeding on the polychaete worm Clymenella mucosa. Gel neither inhibits nor promotes embryo predation for Nassarius, but because it cannot target individual embryos inside an egg mass, its feeding is slow and inefficient, and feeding rates in the field are quite low. However, snails that compete with Nassarius for scavenged food have not been seen to eat egg masses in the field, leaving Nassarius free to exploit the resource. Overall, egg mass predation in these two systems likely benefits the predators much more than it negatively affects the prey. Thus, selection for environmentally protective aspects of egg mass production may be much stronger than selection for defense against predation. </p><p>In the second study, I examined desiccation resistance in intertidal egg masses made by Haminoea vesicula, which preferentially attaches its flat, ribbon-shaped egg masses to submerged substrata. Egg masses occasionally detach and become stranded on exposed sand at low tide. Unlike adults, the encased embryos cannot avoid desiccation by selectively moving about the habitat, and the egg mass shape has high surface-area-to-volume ratio that should make it prone to drying out. Thus, I hypothesized that the embryos would not survive stranding. I tested this by deploying individual egg masses of two age classes on exposed sand bars for the duration of low tide. After rehydration, embryos midway through development showed higher rates of survival than newly-laid embryos, though for both stages survival rates over 25% were frequently observed. Laboratory desiccation trials showed that >75% survival is possible in an egg mass that has lost 65% of its water weight, and some survival (<25%) was observed even after 83% water weight lost. Although many surviving embryos in both experiments showed damage, these data demonstrate that egg mass stranding is not necessarily fatal to embryos. They may be able to survive a far greater range of conditions than they normally encounter, compensating for their lack of ability to move. Also, desiccation tolerance of embryos may reduce pressure on parents to find optimal laying substrata. </p><p>The third study takes a big-picture approach to investigating the evolution of different developmental strategies in cone snails, the largest genus of marine invertebrates. Cone snail species hatch out of their capsules as either swimming larvae or non-dispersing forms, and their developmental mode has direct consequences for biogeographic patterns. Variability in life history strategies among taxa may be influenced by biological, environmental, or phylogenetic factors, or a combination of these. While most prior research has examined these factors singularly, my aim was to investigate the effects of a host of intrinsic, extrinsic, and historical factors on two fundamental aspects of life history: egg size and egg number. I used phylogenetic generalized least-squares regression models to examine relationships between these two egg traits and a variety of hypothesized intrinsic and extrinsic variables. Adult shell morphology and spatial variability in productivity and salinity across a species geographic range had the strongest effects on egg diameter and number of eggs per capsule. Phylogeny had no significant influence. Developmental mode in Conus appears to be influenced mostly by species-level adaptations and niche specificity rather than phylogenetic conservatism. Patterns of egg size and egg number appear to reflect energetic tradeoffs with body size and specific morphologies as well as adaptations to variable environments. Overall, this series of studies highlights the importance of organism-scale biotic and abiotic interactions in evolutionary patterns.</p> / Dissertation

JUHASOVÁ, P., Invertebrate Lectures And Their Use In Leisure Lessons. Master thesis. Praha: Charles univerzsity in Prague, Faculty of Education, 2016. 94 s. In this diploma thesis, practical tasks focused on invertebrate biology are presented. They are targeted for science hobby groups. Detailed instructions for experiments and observations as well as for capturing invertebrates can be found in this diploma thesis. There are described also long-term projects in the form of inquiry-based teaching tasks, construction of man-made outdoor insect nests (so-called "insect hostels") and also the indoor invertebrate keepings. The vast majority of tasks were tested in practice in two science hobby groups, attended by a total of 30 participants. The aim of these tasks is to increase the attractiveness and accessibility of natural science to a wider audience and improving its presentation, but also to arouse positive attitude to nature and all living creatures. Inspiration will be found there not only by leaders of natural science clubs, but also by teachers, who want to incorporate practical work with animals into teaching. Key words: invertebrates, experiment, observation, breeding, inquiry-based edusdion, IBE

M.Sc. (Zoology) / The production of nanoparticles started as early as 1990s (Alkilany & Murphy, 2010). Nanoparticles are utilised in a range of products such as electronics, optics, textiles, medical, devices, cosmetics, food packaging, water treatment technology, fuel cells, catalysts, biosensors and agents for environmental remediation (Handy et al., 2008). Unlike natural particles, which dissolve or aggregate and are often temporary in the environment, engineered nanoparticles (ENPs) maybe persistent due to the stabilization properties of their capping agent (surfactant or organic material). Thus, there is growing concern about the production and fate of ENPs in the environment (Handy et al., 2008).As ENPs pass through the water system they become exposed to different salinities, ionic concentrations and pH changes (Lapresta-Fernández et al., 2012). During this process the ENPs are degraded, transported, altered and accumulated in various ways. Nanoparticles have been found to aggregate in various organelles, for example endocytotic vesicles (Elsaesser & Howard, 2011; Lapresta-Fernández et al., 2012), cytoplasm and the perinuclear region (Mirkin et al., 2010). This can take place via ingestion, endocytosis and or by diffusion (Nowack & Bucheli, 2007). The major question is are NPs toxic and are they more toxic than their metal salts? While bulk gold is distinguished as a chemically inert and a non-toxic substance, (Alkilany & Murphy, 2010) GNPs may be toxic due to their different physicochemical properties such as small particle size, configuration, charge and specific surface area and easy surface alterations (Cho et al., 2009; Goodman et al., 2004; Lapresta-Fernández et al., 2012)...

This thesis applies the food security concept to assess the significance of seagrass-associated invertebrate gleaning for providing food security in Kaole, Tanzania. It assesses the availability, accessibility, utilisation and stability over time of this food source. To explore this, a multi-strategy research design was used. Structured interviews were held with 30 gleaning women in Kaole, using a self-developed questionnaire designed to address the four components of the food security framework. Two focus group discussions were thereafter held to explore how local ecosystem services, in particular seagrass meadows, and their food provisioning services have developed over time. The findings show that a great majority of the women who engage in seagrass- associated gleaning in Kaole rate this activity as important or very important for providing food to the household. The seagrass-associated gleaning activities were perceived as important, despite the fact that most women also glean in the mangrove area and that almost all women have alternative incomes. However, seen from a strict food security perspective, it is questionable how significant this activity currently is for food security. The study found that availability has decreased and it is not a food source that is stable throughout the year. The findings also suggest that the mangrove-associated Terebralia palustris may be easier to utilise, considering that you can store it in a sack, without being kept cold. If mangrove related gleaning hence seems to play an increasingly important role in local food security, and is a fishery that is available in all seasons, this area is less accessible to potential gleaners with small children, elderly and people with physical disabilities. The study also found that the decline in seagrass-associated gleaning activities have coincided with a number of human stressors and deteriorating seagrass meadows. Despite its’ declining signinficance for food security, most women rate the seagrass-associated gleaning as important and want to protect this food source. Action should therefore be taken to sustainably preserve this provisioning resource. Bearing in mind the fine balance between ecological and food security needs, such measures need to be interdisciplinary. It also needs to involve different community members, as well as other stakeholders. More research would be needed to determine the nutritional content and potential toxic contents in the most fished invertebrate species.