The illegal sale of East Coast rock lobster (Panulirus homarus) along the N2 highway at Mfazazana on the south coast of KwaZulu-Natal, continues to create tension between the local community and conservation and other authority structures in the region. Panulirus homarus (P. homarus) is a valuable commodity in an area distant from industry and other economic prospects and is within easy reach of both the harvester, in terms of its intertidal living space and the market, in terms of the N2 and the economy in seafood prevalent in the region. P. homarus is therefore at risk by virtue of its biology and habitat, and the illegal nature of its capture tests the parameters of sustainable resource management still further. This research addresses the issue of sustainable resource use through an examination of the perceptions of the various stakeholders who are involved in the use and protection of P. homarus at Mfazazana. This study was commissioned by the Communications Section of the KwaZulu Department of Nature Conservation (KONC) in response to continued illegal harvesting and trade of P. homarus at Mfazazana. One of the mandates of the Communications Section is to initiate and maintain environmental education programmes and thus comply with the KONC mission statement (See Appendix 1a). Specific objectives of the study include: • how respondents perceive their relationship with, responsibility to and role in terms of P. homarus • how respondents perceive their relationship with, responsibility to and role in terms of the others involved with P. homarus • how present legislation is perceived by stakeholders • what options exist regarding the regulation and/or management of P. homarus • whether changes over time have occurred in the respondents' relationship with P. homarus Fishing and trading activities were inv~stigated using informal, loosely structured questionnaires which elicited qualitative information. Two main groups were selected. and respondents were interviewed either individually or in small groups. The crayfishers made up the first group and the resource managers made up the second group which included the Natal Parks Board (NPB), the KONG, the Hibberdene Tourism and Publicity Association, the Community Policing Forum, the Community Development Forum at Mfazazana and the South Coast Fishing Forum. The study provided an understanding and explanatiol] of how the elements of the locality interact with underlying structures and human agency in time to produce the conflict over the marine resource P. homarus at Mfazazana. It was found that the conflict between stakeholders, as a result of differing perceptions regarding the illegal harvesting of the resource, was obstructing the sustainable management of P. homarus at Mfazazana. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997

A series of acute (96h) toxicity tests were conducted on six species of crayfish inthe family Cambaridae. Toxicity values fell into a sensitive group comprising Orconectesplacidus and Procambarus acutus (LC 50= 0.368mg Cd/L - 0.487mg Cd/L; LC10= 0.048mg Cd/L - 0.092 mg Cd/L) and tolerant group comprising O. juvenilis, O. virilis, P.alleni, and P. clarkii (LC 50= 2.44 mg Cd/L - 3.30 mg Cd/L; LC10= 0.386 mg Cd/L -0.947 mg Cd/L). For juvenile crayfish, the LC50 and LC10 values were as follows: O.juvenilis, 0.060 and 0.014 mg Cd/L; O. placidus, 0.037 and 0.002 mg Cd/L; P. clarkii,0.624 and 0.283 mg Cd/L. Cd exposure decreased molting success highlighting theimportance of this sensitive process. Behavioral responses were assessed in O. placidus,O. virilis, P. acutus, P. alleni, and P. clarkii. The tail-flip predator avoidance behaviorwas significantly reduced by cadmium exposure. In most species tested, the claw raisedefensive behavior was significantly increased by Cd exposure. Between species, as bodymass increased, the tail-flip response frequency decreased, and the claw-raise responseincreased in frequency. P. clarkii was also analyzed for the effect of Cd exposure onheart rate and response to two stimuli. The data indicate that heart rate may be a usefulphysiological marker of Cd toxicity. The major organ systems were dissected fromsurvivors of four adult crayfish toxicity tests (O. juvenilis, O. placidus, P. acutus, P.clarkii) and analyzed for metal content. Cadmium tissue content correlated with Cdexposure. Cadmium accumulated more in the hepatopancreas, gills and green glands ofsensitive species than in tolerant species. Zn showed negative correlations with Cdexposure in the hepatopancreas. Cu increased in green glands, gills, and hemolymph and,in some cases, decreased in the hepatopancreas. Ca, Fe, Mg, and Zn also showedsignificant trends. Zn accumulated in the exposure water over 24h. These data indicatethat Cd may displace Cu and/or Zn in the hepatopancreas and the displaced metal thenmay move into other tissues, especially the gills and green glands, possibly to beexcreted.

Sensory biology of animals is studied throughout the world for the insight it provides to understanding ecosystems and improving how we manage species. In this research, I designed experiments to investigate the sensory biology and behaviour of two Australian species of freshwater crayfish from the genus Cherax, the yabby (Cherax destructor) and redclaw crayfish (Cherax quadricarinatus). Experimental apparatus were constructed and tailored to test specific questions on physiology, tactile (touch) sensitivity, observation techniques, aggressive behaviour and responses to electrical fields. The outcomes were: / • abdominal muscle mass was positively correlated to the size of the electrical fields produced by swimming crayfish, / • behaviour changed in response to contact with different structures and textures of wall surfaces, / • computer analysis of underwater behaviour was similar to that scored by a human observer, / • the level of aggression in groups of crayfish changed as group size increased, and / • two species of crayfish responded to electrical fields in the water by decreasing their locomotory movement. / These results reveal a way in which physiology relates to behaviour, how crayfish and other crustaceans may sense the invisible and behave in aquaculture ponds, as well as documenting methodology to further investigate these areas in the future.

Thesis (M.S.)--Bowling Green State University, 2008. / Document formatted into pages; contains vii, 68 p. : ill. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 186-194).

The compound m-chlorophenylpiperazine (m-CPP) is used clinically to manipulate serotonergic function, though its precise mechanisms of actions are not well understood. m-CPP alters synaptic transmission and neuronal function in vertebrates by non-selective agonistic actions on 5-HT1 and 5-HT2 receptors. In this study, we demonstrated that m-CPP did not appear to act through a 5-HT receptor in depressing neuronal function in the invertebrates (crayfish and Drosophila). Instead, m-CPP likely decreased sodium influx through voltage-gated sodium channels present in motor and primary sensory neurons. Intracellular axonal recordings showed that m-CPP reduced the amplitude of the action potentials in crayfish motor neurons. Quantal analysis of excitatory postsynaptic currents, recorded at neuromuscular junctions (NMJ) of crayfish and Drosophila, indicated a reduction in the number of presynaptic vesicular events, which produced a decrease in mean quantal content. m-CPP also decreased activity in primary sensory neurons in the crayfish. In contrast, serotonin produces an increase in synaptic strength at the crayfish NMJ and an increase in activity of sensory neurons; it produces no effect at the Drosophila NMJ. In the rat spinal cord, m-CPP enhances the occurrence of spontaneous excitatory postsynaptic potentials with no alteration in evoked currents.

The rewarding properties of drugs in the mammalian system depend on their ability to activate appetitive motivational states. The associated underlying mechanism is strongly conserved in evolution and invertebrates have recently emerged as a powerful new model in addiction research. The natural reward system in crayfish has surprisingly proven sensitive to human drugs of abuse, providing a new model for research into the basic biological mechanisms of drug addiction. In this study, we examined the presence of natural reward systems in crayfish, and then characterized its sensitivity to 2.5 μg/g, 5.0 μg/g and 10.0 μg/g doses of methamphetamine (METH). Using the conditioned place preference (CPP) paradigm, we demonstrated that irrespective of the number of doses of METH injected into the pericardial system, crayfish seek out a particular tactile environment that had previously been paired with the METH. This study demonstrates that crayfish offer a comparative and complementary approach in addiction research. It contributes an evolutionary context to our understanding of a key component in learning and of natural reward as an important life-sustaining process.

Hemocytes are an important part of a crayfish’s immune system in helping tackling both virus and bacterial infections. Dscam is a protein that can be found in hemocytes, as well as many other tissues like the brain. In the brain, Dscam is thought to be important in the establishment of neuronal connections. Previous studies have found that the neurons in the crayfish brain do not replenish themselves, but instead are replenished by hemocytes that enter through a vascular cavity that pass through the neurogenic niche. There might be a specific type of hemocyte that is drawn to the niche and because of the link between Dscam and establishment of neuronal connections, Dscam have been chosen as a potential factor for this attraction. Dscam could be upregulated at many places along the way from the HPT to the brain. In this study, antibodies have been used to view BrdU and Dscam presence in hemocytes from crayfish P. leniusculus to find out where Dscam is upregulated and in what cells they are located. It was found that Dscam is not present on newly synthesized cells but rather on more differentiated cells, suggesting that Dscam is upregulated in older HPT cells or in circulation. It was found that LPS injections are an efficient way to upregulate Dscam in hemocytes and that expression of extracellular Dscam is peaking 24 hours post LPS injection.

The host-parasite interface between the branchiobdellid Cambarincola vitrea Ellis and its crayfish host is investigated along ecological, ultrastructural, serological, and endocrinological lines of evidence. Monthly analysis of a natural branchiobdellid from a vernal habitat demonstrates the annelid to be particularly sensitive to changes involving both the physical habitat as well as the host crayfish.

No description available.