A recirculating seawater aquarium system for inland laboratories

We have designed and installed a 7,500 l recirculating aquarium system for the purpose of maintaining marine gastropods in an inland laboratory. It is completely nonmetallic and can be adapted for any number of isolated living compartments. Vonvenient and efficient filtration is achieved by the use of disposable cartridge filters. The water temperature is regulated by a direct expansion cooling coil and a hot water heating coil without the intervention of secondary heat transfer fluids. Most of the water is stored in an underground reservoir which contributes to thermal stability, and the water temperature varies <±0.1°C per week. The pH and specific gravity remain at 8.0±0.1 and 1.023+0.002-0.001, respectively, for as long as 4 months. We have no evidence that any animal (Aplysia, Hermissenda, Tritonia) has died due to poor water quality. The system is constructed from readily available components, is moderate in cost, and has performed reliably for over 2 years.     

Ecological and hormonal correlates of antipredator behavior in adult Belding’s ground squirrels (Spermophilus beldingi)

Predator–prey relationships provide an excellent opportunity to study coevolved adaptations. Decades of theoretical and empirical research have illuminated the various behavioral adaptations exhibited by prey animals to avoid detection and capture, and recent work has begun to characterize physiological adaptations, such as immune reactions, metabolic changes, and hormonal responses to predators or their cues. A 2-year study quantified the activity budgets and antipredator responses of adult Belding’s ground squirrels (Spermophilus beldingi) living in three different California habitats and likely experiencing different predation pressures. At one of these sites, which is visually closed and predators and escape burrows are difficult to see, animals responding to alarm calls remain alert longer and show more exaggerated responses than adults living in two populations that likely experience less intense predation pressure. They also spend more time alert and less time foraging than adults at the other two sites. A 4-year study using noninvasive fecal sampling of cortisol metabolites revealed that S. beldingi living in the closed site also have lower corticoid levels than adults at the other two sites. The lower corticoids likely reflect that predation risk at this closed site is predictable, and might allow animals to mount large acute cortisol responses, facilitating escape from predators and enhanced vigilance while also promoting glucose storage for the approaching hibernation. Collectively, these data demonstrate that local environments and perceived predation risk influence not only foraging, vigilance, and antipredator behaviors, but adrenal functioning as well, which may be especially important for obligate hibernators that face competing demands on glucose storage and mobilization.     

Some notes on Tubiluchus corallicola (Priapulida) from Barbados,West Indies

The occurrence of Tubiluchus corallicola (van der Land) in a lagoon on the East coast of Barbados, West Indies, is reported. 23 adult and 2 larval specimens were found in a sample taken from a subtidal stromatolite on which the animals presumably inhabited the algal surface layer. A comparison with data from earlier findings shows that the species is not confined to a particular type of substratum, yet morphologically it seems to be well adapted for a life in the interstitial sand habita. For the first time, living animals were observed and photographed. Their behavior and movements are briefly described and an account of morphological and histological details, as seen in squeezing preparations and photomicrographs, is presented.Supported in part by NSF Grant GB-7952     

Preparation and evaluation of protein microcapsules for a marine suspension-feeder,the Pacific oyster Crassostrea gigas

Little is known of the dietary requirements of marine suspension-feeders, mainly due to difficulties in preparing and delivering microparticulate diets to animals living in an aquatic environment. The food particles must be stable in seawater and digestible by the consumer. A laboratory method for preparing cross-linked, protein-walled capsules is described in this study as a means of delivering dietary protein to marine suspension-feeders such as the oyster Crassostrea gigas. Leakage of ¹⁴C-labelled protein from capsules suspended in seawater for 24 h was reduced to less than 5% by the use of the trifunctional cross-linking agent 1,3,5-benzenetricarbonyl trichloride in wall formation. Invitro experiments indicated that capsules were susceptible to digestion by proteases and by style extracts of oysters. Oysters fed encapsulated ¹⁴C-labelled protein absorbed ¹⁴C with an efficiency of 40.2±5.0% (±1 SE). Biochemical fractionation of capsule-fed oysters indicated breakdown of ingested ¹⁴C-protein into material that was soluble in 7% trichloroacetic acid. Cross-linked, protein-walled capsules can be used successfully to deliver dietary protein to the oyster C. gigas.     

Relationship between egg features and maternal body size in the simultaneous hermaphrodite <Emphasis Type="Italic">Oxynoe olivacea</Emphasis> (Mollusca,Opisthobranchia, Sacoglossa)

This paper provides information on spawn morphology and egg features of the stenophagous planktotrophic Mediterranean sacoglossan Oxynoe olivacea. Smith and Fretwell’s hypothesis, predicting that individuals of the same population growing in the same environmental conditions and varying in size should spawn eggs of a constant size, was tested in a population of O. olivacea living in the Straits of Messina. To determine whether (a) spawn mass size, (b) total egg number per spawn, and (c) egg size were related to parent size of O. olivacea, 21 egg masses (seven egg masses deposited by seven different 20 mm animals, seven egg masses deposited by seven different 25 mm animals and seven egg masses by seven different 30 mm animals) were randomly chosen and examined. Results showed that both spawn mass width and number of eggs per spawn mass increased across O. olivacea body size and apart from the significant variation of the short capsule diameter, there was no consistent variation of egg features in O. olivacea. In conclusion the species allocates constant amounts of energy to individual embryos and thus supports the prediction designed by Smith and Fretwell.     

The structure and sensitivity of the eye of different life history stages of the ontogenetic migrator Gnathophausia ingens

The structure and ultrastructure of the photoreceptors of several life history stages of the ontogenetically migrating lophogastrid crustacean Gnathophausia ingens were examined. The younger instars of this species live in a much brighter light field than the older instars, and this difference is reflected in differences in their visual systems. The shallowest free living individuals (instars 3 and 4) possess a superposition eye with almost no clear zone, which minimizes the light shared between ommatidia and reduces the sensitivity of the eye. A progression to superposition optics with a large clear zone, usually associated with night-active or deep-living species, occurs as the animals move deeper in the water column. Regional differences within the eye are also evident, with a largely nonexistent clear zone in the dorsal region and a large clear zone in the ventral region in the eyes of instar 5 animals, the first instar to move to deeper depths. The deepest living instars (10–12) possess superposition optics with a large clear zone throughout the eye, and are significantly more sensitive to light than the younger, shallower instars.     

Aposematism in a soft-bodied insect: a case for kin selection

Summary This paper describes the influence on predator behaviour, and the survival of an aposematic aphid, Aphis nerii, in comparison with a palatable, cryptic aphid, Acyrthosiphon pisum, when offered to two predators with different foraging tactics. The experiments were designed to test Fisher's (1930) suggestion that aposematism could evolve by kin selection, since aposematic animals often occur in aggregations of relatives. Initially, spiders (Zygiella x-notata) and birds (Parus major) killed high proportions of distasteful A. nerii (60% and 54% respectively). With experience, the predators killed and ate fewer A. nerii. The decreasing mortality of A. nerii after initial encounters with predators, coupled with its apparently obligate parthenogenesis, indicate that the evolution of aposematism in this soft-bodied insect is consistent with kin selection.     

Movements of vervets (Cercopithecus aethiops) and patas monkeys (Erythrocebus patas) as estimators of food resource size, density, and distribution

The effect of food resources on behavior has been difficult to measure. Here we use animals themselves to describe “effective” food abundance and distribution by comparing, relative to where individuals stopped to eat, movements of (1) adult females living in a small group of vervet monkeys (Cercopithecus aethiops) with those living in a large group and (2) vervets and patas monkeys (Erythrocebus patas). Although females in the large vervet group travelled farther and stopped to eat more often than females in the small vervet group, these differences resulted from foraging in Acacia drepanolobium habitat. In A. xanthophloea habitat, females in the large group travelled less far, travelled shorter distances between foods, and stopped as often as females in the small group. Greater foraging costs of females in larger vervet groups may be offset by access to home ranges of better quality. Compared to patas, vervets travelled shorter distances, moved shorter distances between food sites, stopped less often, and had longer feeding bouts, suggesting that foods of vervets are denser and larger, overall, than foods of patas. When vervets foraged in A. drepanolobium habitat, also the habitat of patas, their foraging behavior became more like that of patas. Vervets travelled farther, stopped more often, and spent less time at food sites in A. drepanolobium habitat than in A. xanthophloea habitat, suggesting that foods are smaller and less usurpable in A. drepanolobium habitat. Distance between foods, a component of food distribution, did not increase, however. The critical variable underlying usurpability of foods may be food site depletion time, a temporal measure. Received: 14 March 1997 / Accepted after revision: 19 October 1997     

Large males dominate: ecology,social organization,and mating system of wild cavies,the ancestors of the guinea pig

Ecological factors differently affect male and female animals and thereby importantly influence their life history and reproductive strategies. Caviomorph rodents are found in a wide range of habitats in South America and different social and mating systems have evolved in closely related species. This permits to study the impact of ecological factors on social evolution. In this study, we investigated the social organization and the mating system of the wild cavy (Cavia aperea), the ancestor of the domestic guinea pig, in its natural habitat in Uruguay. Based on our laboratory investigations, we expected a polygynous system with large males controlling access to females. Results from radiotelemetry and direct observations showed that females occupied small stable home ranges which were largely overlapped by that of one large male, resulting in a social organization of small harems. In some cases, small satellite males were associated with harems and intermediate-sized roaming males were occasionally observed on the study site. However, microsatellite analyses revealed that offspring were exclusively sired by large males of the same or neighboring harems, with a moderate degree of multiple paternity (13–27%). Thus, the mating system of C. aperea can be described as polygynous and contrasts with the promiscuous organization described for other species of cavies (Cavia magna, Galea musteloides and Microcavia australis) living under different ecological conditions. Our findings stress the strong impact of environmental factors on social evolution in Caviomorphs as resource distribution determines female space use and, thereby, the ability of males to monopolize females. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Chromium Concentrations in Geobotanical Samples from West Pokot District, Kenya

The study analyses chromium concentration in plants growing around an area of chromite mineralisation, and proposes that the availability of chromium in plants could have adverse health effects when ingested by domestic animals and ultimately by the human population. This geoepidemiological attribute of geobotany has been observed in the form of chromium eczema in humans. The study was undertaken in the Sekerr Sub-location West Pokot District, which is located in the humid tropical region of the Republic of Kenya. As well as having natural vegetation cover, there are no sources of airborne pollutants in the area, which would vitiate trace element analysis in geobotanical research. The assay results show that the species Satureja abyssinica, Protea kilimandischarica, Ficus sycomorus, and Maerua subcordata have high chromium concentrations. These plants are generally browsed by domestic animals and are in turn eaten by humans. It is, therefore, proposed that a detailed analysis of chromium concentration in blood samples of both domestic animals and the human population be undertaken in order to assess its concentration levels in the population living in this geochemical environment.     

Occurrence of marine resident tropical eel Anguilla bicolor bicolor in Indonesia

In order to understand the migratory history and habitat use of the tropical anguillid eels Anguilla celebesensis, A. marmorata, and A. bicolor bicolor, the otolith strontium (Sr) and calcium (Ca) concentrations were examined for eels collected in Indonesian waters. In A. bicolor bicolor collected in a lagoon, the change in Sr:Ca ratios outside the high Sr:Ca core generally indicated two patterns of habitat residence: (1) constant living in either brackish or sea waters with no freshwater life (25%) and (2) habitat shifts from fresh water to brackish or sea waters (75%). No A. bicolor bicolor had a general life history as a freshwater resident. A. celebesensis and A. marmorata from the uppermost freshwater lake showed freshwater life history patterns. The wide range of otolith Sr:Ca ratios in A. bicolor bicolor indicated that the habitat use of this tropical eel was facultative among fresh, brackish, and marine waters during the growth phase after recruitment to coastal areas similar to that for temperate eels. Thus, the migration of anguillid eels into fresh water is clearly not an obligatory.     

Sociality reduces individual direct fitness in a communally breeding rodent,the colonial tuco-tuco (<Emphasis Type="Italic">Ctenomys sociabilis</Emphasis>)

In many social vertebrates, remaining in the natal group leads to at least short-term reductions in the direct fitness of philopatric animals. Among communally breeding rodents, the direct fitness costs of philopatry appear to increase as the frequency of successful natal dispersal decreases, suggesting a functional link between constraints on natal dispersal and the reproductive consequences of sociality. To explore this relationship empirically, I documented patterns of direct fitness among female colonial tuco-tucos (Ctenomys sociabilis), which are group-living subterranean rodents from southwestern Argentina. Demographic data suggest that successful natal dispersal is rare in this species, leading to the prediction that natal philopatry in C. sociabilis is associated with significant reductions in individual direct fitness. Using data obtained during 1996–2001, I compared the direct fitness of females that dispersed from their natal group and bred alone as yearlings to that of females that lived and bred in their natal group as yearlings. Philopatric yearlings reared significantly fewer young to weaning than did disperser (lone) yearlings. Although neither survival to a second breeding season nor the estimated lifetime number of pups reared to weaning differed between dispersal strategies, the annual direct fitness of group-living females was 23–40% less than expected, suggesting that philopatric animals experienced a substantial direct fitness cost by remaining in their natal group. These data yield important insights into the adaptive bases for group living in C. sociabilis and suggest that constraints on natal dispersal are an important factor favoring group living in this species.Communicated by J. Wilkinson     

Laboratory system enabling long-term exposure (⩾ 30 d) to hydrostatic pressure (⩽ 101 atm) of fishes or other animals breathing water

A high-pressure water-circulation system is described which enables fish (or other animals breathing water) to be maintained at pressures up to 101 atm for at least one month. A typical experiment, measuring the oxygen consumption of the eelAnguilla anguilla over a period of 31 d, revealed a metabolic acclimation to pressure in this fish. This system has numerous advantages; e.g. it is possible to reproduce in situ environmental conditions at depth, thus enabling the study of the problems of pressure adaptation, and also to simulate vertical migrations of animals, allowing the study of associated physiological phenomenon.     

Significance of mangrove–mudflat boundaries as nursery grounds for the mud crab, Scylla paramamosain

Fisheries managers frequently try to protect juveniles in order to preserve stocks. Juveniles can be protected by either implementing changes designed to avoid catching immature animals (e.g. increasing mesh size or altering fishing techniques) or protecting nursery grounds. To prevent the capture of immature animals, an estimate of size at maturity is required as well as a knowledge of both fishing methods and the exact location of the nursery grounds. Strong demand for juvenile mud crabs to stock aquaculture ponds has resulted in development of fisheries targeting crabs of all sizes from instar 1 to mature individuals. Using five different fishing methods, different stages in the life cycle of Scylla paramamosain were followed for a period of 16 months in an estuarine population in the Mekong Delta, Vietnam. Mangrove habitat utilisation begins when crabs settle out from the plankton at instar 1 [modal internal carapace width (ICW), 0.5 cm] amongst the pneumatophores at the mangrove fringe. Increasingly larger crabs were found deeper into the mangrove but they were still living on the surface (modal ICW size class, 1.5 cm). As their size increases, the crabs either dig burrows (modal ICW size class, 4.5 cm) or they live in the sub-tidal zone, migrating into the mangrove with each tide to feed (modal ICW size class, 4.5 cm). Larger crabs were caught offshore (modal ICW size class, 12.5 cm) where females accounted for 60% of the catch although of these, only 63% were mature. Recruitment of early instars was continuous but peaked in December to February. Subsequent peaks in the catch rates of larger size classes indicated the development of a single cohort with an estimated growth rate of 2.0 cm ICW per month. On the basis of abdominal width, females were estimated to mature at 10.2 cm ICW although at 9.7 cm ICW, 50% of females had disengaged abdomens. Abdominal disengagement occurred in males at the slightly smaller size of 9.1 cm ICW. Allometric relationships between chela height and carapace width suggested 50% of males acquire mature chelae at 10.2 cm ICW. These results demonstrate the close linkage between early life stages of S. paramamosain and certain specific niches within mangrove habitats, with the main adult population found to be living sub-tidally at some distance from the mouth of the estuary. The study also highlights the special importance of the mangrove fringe, the border between the mangrove forest and the sea, an area which is particularly vulnerable to physical and anthropogenic impacts.     

Shell gaping behaviour of <Emphasis Type="Italic">Pinna nobilis</Emphasis> L., 1758: circadian and circalunar rhythms revealed by in situ monitoring

Gaping activity of bivalve molluscs is closely related to physiological process such as breathing, nutrition, responses to environmental stimuli and follows rhythmic cycles in many species. Although the alternation of Sun and Moon is the major entraining agent for the daily living clock-driven rhythms, cyclic extrinsic environmental factors can also modulate gaping activity. Therefore, laboratory experimental conditions can alter the natural behaviour of bivalves, hindering the interpretation of observations. Many features of Pinna nobilis physiology are poorly known, gaping activity not being an exception. To reduce the knowledge gap on this regard, we performed a study on the species gaping activity. The research was designed to be carried out in situ, in order to avoid the interference of laboratory conditions in the observations. To this end, we designed and fabricated a new electronic system composed by a data logger and a sensor formed by multiple reed switches activated by a single magnet. The system is autonomous and can record gaping activity of subtidal bivalves in potentially any type of subtidal environment. Furthermore, it requires little framework for the installation. With this system, we monitored 10 individuals in periods ranging between 3 and 21 days, for up to a total of 98 days. The records have shown that far from being all day open, as previously suggested, P. nobilis follows marked circadian and circalunar rhythms of gaping activity. Individuals usually close the valves during night, sometimes for more than 12 h. The repetition of patterns observed made it possible to distinguish between two main behaviours: (1) night-closing related with sunset and (2) night-opening related with the Moon visible in the sky with the disc illuminated more than 50%. Another two less common trends were also observed: (3) day-closing and (4) night-opening with no visible Moon.     

Lipid class and glycogen content of the lugworm Abarenicola pacifica in relation to age,growth rate and reproductive condition

We measured the levels of lipid classes (wax esters, triacylglycerides, free fatty acids, sterols, phospholipids) and levels of glycogen in a population of Abarenicola pacifica over a one-year period beginning shortly after recruitment. Glycogen and lipid contents were unrelated to growth rates as estimated by changes in average size of individuals in the cohort. There was no indication of seasonality in levels of any component, consistent with the hypothesis of Slobodkin and Richman that animals living in environments where food supplies are likely to be stable, such as subsurface deposit-feeders like A. pacifica, do not accumulate energy reserves. Instead, glycogen content increased gradually and most lipid classes decreased gradually over time. A notable exception was the triacylglyceride content, which showed a large increase associated with the formation of eggs. Triacylglyceride levels in older A. pacifica and in two other species of depositfeeding polychaetes showed similar trends. Measurement of triacylglyceride levels may provide an additional objective method, supplementing egg counts and egg size, of quantifying reproductive effort in deposit-feeders.     

Removal,adsorption and desorption of pentachlorophenol (PCP) by filamentous fungi: Rhizopusarrhizus and Cunninghamella elegans in batch system

PCP was, and in some countries still is, one of the most frequently used fungicides and pesticides, specially in wood preservation. The extensive use is correlated with contamination of water and soil and it is detected in several compartments of the food chain.

Some Micromycetes are able to adsorb and degrade PCP, with two mechanisms involved: biosorption (including both adsorption and absorption) and biodegradation.

Our work is focused on the biosorption alone and biodegradation‐biosorption of PCP by respectively denatured and living R.arrhizus and C.elegans fungi.

Living fungi are cultivated in batch system and denaturation is obtained by drying (70°C) and grinding the fungi to a calibrated powder (200–400 μm). Kinetic studies are performed with 10 mg/1 PCP initial concentration. Adsorption capacity is measured at equilibrium concentration as high as about 400 mg/1 PCP.

The results show that: PCP adsorption, for the two fungi, follows a two steps process. R. arrhizus dead and living biomasses are able to bind respectively, 75 and 55% of a 10 mg/1 PCP initial concentration in 1 hour contact time and then 75 and 100% in 96 hours. For C.elegans, 70 and 28% in 1 hour and in 96 hours 70 and 90%, respectively.

The PCP binding by living fungi is higher than non living ones, but with a slower rate.

The maximum PCP adsorption capacity is about 24 mg/g of R.arrhizus dried biomasses and 16 mg/g for C.elegans ones, in 48 hours contact time. Isotherm curves follow the Langmuir model.

Desorption studies with methanol (to reuse biomasses) shows that it is a rapid phenomenon (about 100% in 24 hours for the two fungi).

An industrial and economical process to depollute contaminated water by PCP is possible by using cheap fungal by‐products from fermentation industries.     

No sympathy for the devil

Pathogens are a significant driver of biodiversity loss. We examine two wildlife disease management strategies that have seen growing use, sometimes in combination: (i) trapping-and-culling infectious animals (disease control), and (ii) trapping-and-translocating healthy animals to a reserve, with possible future reintroduction. A reserve can improve conservation when there is no disease. But, when infection exists, we show investing in the reserve may counteract disease control. We find jointly pursuing both strategies is sub-optimal when the reserve is costly to maintain. Numerically, we examine management of Devil Facial Tumor Disease, which has generated extinction risks for Tasmanian Devils. Disease control (though not eradication) is generally part of an optimal strategy, although a reserve is also optimal if it can be maintained costlessly. This implies preserving the original population by addressing in situ conservation risks, rather than translocating animals to a reserve and giving up on the original population, is generally the first-best.     

Feeding of Pseudocalanus minutus on living and non-living particles

A seasonal study of carbon content of living and of carbon and nitrogen content of non-living particulate material in seawater is presented. Grazing by Pseudocalanus minutus on living and non-living particles has been investigated over 1 year. Seasonal variations in the food uptake were associated with seasonal variations of each chemical component of the particles in the water. The amount of non-living carbon constituted the major part of the food ingested, irrespective of season. The ingested living carbon always accounted for a small fraction of the total copepod body carbon. The proportion of living carbon ingested could be equivalent to or even higher than non-living carbon at times during the late spring, summer and fall. The concentration of both living and non-living material within each particle peak of the spectra in the water seemed to affect the balance between non-living and living particle uptake. Non-living particles cannot be considered only as a supplementary food source for small copepods; they are a basic food for P. minutus at all times.     

Uptake of polychlorinated biphenyls from sea water by Gammarus oceanicus

The uptake of a polychlorinated biphenyl preparation containing 5 to 7 chlorine atoms/molecule, solubilized in a nonionic surfactant in sea water, by Gammarus oceanicus was measured spectrophotometrically. Uptake occurred in living animals across the general integument. It is suggested that uptake rates are dependent upon the total surface area of the integument, although no accurate method of determining this is known. The rate of uptake decreased after 4 to 6 hours exposure and uptake was dependent upon concentration of polychlorinated biphenyls in sea water. The stage of the intermoult of G. oceanicus did not affect uptake rates.