Florida manatees, Trichechus manatus latirostris, respond to approaching vessels

Florida manatees inhabit shallow coastal and estuarine waters of the southeast US, a range that brings them into frequent contact with vessels. More than 30% of documented annual mortalities are attributed to vessel collisions, and most living animals bear the scars of multiple, non-lethal encounters. To document the behavior of manatees in the presence of vessels, we recorded their movements with an overhead video system. We scored six aspects of behavior during 170 vessel approaches, and compared their behavior with 187 control segments when no boats were present. Manatees in shallow waters and at the edge of the channel responded to approaches by orienting towards the nearest deep water, a boat channel, and increasing their swimming speed. Close boat approaches and shallow water depths exacerbated these responses. Our results indicate that manatees detect and respond to approaching vessels with an apparent flight response, a response which includes movement towards deeper water. If given sufficient time, i.e., approached or passed slowly, the manatees may then be able to reach deeper water and safe depths.     

Distribution and abundance of manatees trichechus manatus in the Dominican Republic

Aerial surveys and interviews were conducted in the Dominican Republic to determine the distribution and abundance of manatees. Results show that two reproducing populations range through marine habitat of northern and southwestern coastal segments. Calves were seen throughout the year, indicating continuous breeding.Illegal hunting is identified as the major source of mortality and stricter enforcement of existing laws would help to preserve the remaining population.     

Tolerance of West Indian manatees to capture and handling

Ninety-two West Indian manatees (Trichechus manatus) have been captured in the southeastern United States from October 1975 through November 1983 with no evidence of an unusual susceptibility to capture myopathy. Of these, 53 were radio-tracked or observed in the field following capture with no evidence of delayed capture stress. Blood samples obtained at capture for 20 wild individuals displayed no elevation in biochemical variables typically seen in mammalian capture myopathy cases. Thirty-one manatees captured for rescue and rehabilitation generally did not exhibit symptoms of capture myopathy, although in one case marked elevations in creatinine phosphokinase were observed, probably related to lengthy transport. Necropsy findings for 20 terminal cases that died of various causes unrelated to their rescue or handling did not indicate the involvement of any gross or histological lesions of capture myopathy. Historical records for the capture and handling of about 150 West Indian manatees during the 1900s also suggest a tolerance to these activities. Recent observations on the probable susceptibility of dugongs (Dugong dugon) to capture stress apparently cannot be extended to West Indian manatees.     

Distribution and status of manatees Trichechus spp. Near the mouth of the amazon river,Brazil

Interviews with hunters and collection of skulls indicate that Trichechus inunguis occurs throughout the region of the Amazon River estuaries from Amapá to the mainland of Pará, including Ilha de Marajó and islands on its Atlantic coast. T. manatus has a disjunct distribution in Brazil, apparently occurring both on the coast of Amapá north of Cabo Norte and in the Rio Mearim (Maranhão) as well as further to the southwest; it seems to have been exterminated from the Atlantic coast of Pará and is absent from the Marajó region. Continued subsistence hunting can best be controlled by destruction of illegal camboas (fence-like traps) which catch manatees at high tide. Areas deserving study are the coast and inland lakes of eastern Amapá, the only place in the world where two sirenian species might still be found in sympatry or immediate proximity, and the lower Rio Mearim in Maranhão, which may still contain a sizable population of T. manatus. Ecological studies in these areas should have particular relevance to hypotheses of sirenian evolutionary interactions, and manatee reserves should be established in both areas.     

Genetic diversity in California sea otters: Theoretical considerations and management implications

The California sea otter population was reduced to a small number of animals by fur hunters in the 18th and 19th centuries. The population has partially recovered but is still threatened, largely because of its vulnerability in the event of a major oil spill. The translocation of enough animals to establish a second colony outside the present range has been suggested as a means of reducing the vulnerability of the population.Any population that has been reduced to a small number and then allowed to increase may have lost some of its original genetic diversity. The loss of genetic diversity often results in deleterious effects, such as increased juvenile mortality and reduced fertility. It is therefore of interest to determine the degree of genetic diversity which the California sea otter population should have theoretically lost during its population ‘bottleneck’ and the number of otters which should be translocated in order to avoid substantial loss of genetic diversity in the new colony.Application of some of the concepts of population genetics to the California sea otter indicates that the current population should theoretically retain a large proportion (77%) of whatever genetic diversity existed in the original population and that a new colony resulting from the successful translocation of 50 breeding otters would retain much of the present genetic diversity after 40 years.     

Commercial exploitation of manatees Trichechus in Brazil c. 1785–1973

All available published statistics on the exploitation of the Amazonian manatee Trichechus inunguis are collected and analysed to determine the major trends in exploitation and, if possible, their effects on the species. The manatee's role in the Amazonian economy has traiditionally been on the level of subsistnce hunting for local consumption; export of surplus manatee products has been limited and sporadic, and keeping of records has been even more so. Unknown quantities of manatee meat were shipped to the Guianas and West Indies in the 17th century, At least from the 1780s to about 1925, the only manatee product common in Amazonian commerce was mixira (fried meat packed in lard). From 1935 to 1954, manatee hides were exported to southern Brazil and elsewhere for the manufacture of heavy-duty leather. From 1954 to the legal banning of manatee hunting in 1973, manatees were again heavily exploited for meat. At no time did manatee products make up more than a small fraction of a percent of the Amazon region's trade. Numbers of animals killed per year cannot be determined with any precision, but early statistics on mixira reflect no more than 1000/year, while the peak years of hide and meat production probably required 4000–7000 manatees/year, exclusive of unrecorded subsistence hunting. Taking the latter into account, it is likely that actual mortality ran to several thousand animals per year throughout the past two centuries. Decline of meat production in the 1960s may reflect overexploitation. Evidence was also found of some exploitation for meat of West Indian manatees T. manatus in the states of Alagoas and Bahia, Brazil, the latter constituting the southernmost record of the species since the early 19th century.     

Ecological consequences of invasive lake trout on river otters in Yellowstone National Park

The introduction of lake trout (Salvelinus namaycush) to Yellowstone Lake in Yellowstone National Park has contributed to a significant decline in the endangered Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri), leading to concern over the persistence of this subspecies but also to piscivorous predators in this community. We assessed the impact of lake trout on a key piscivore, the river otter (Lontra canadensis) in two lakes in Yellowstone National Park. Yellowstone Lake continues to support a native cutthroat trout population, although the recent introduction of lake trout has dramatically impacted the cutthroat trout population. Nearby Lewis Lake has an entirely introduced fish fauna of lake trout, brown trout (Salmo trutta), and Utah chub (Gilia atraria) but lacks cutthroat trout. Analysis of otter scat from Yellowstone Lake implicated trout (lake or cutthroat trout) as a major prey item (57% of scat), whereas stable isotopes identified longnose suckers (Catostomus catostomus) as the primary prey there (58% of diet). By contrast, scat from Lewis Lake implicated minnows, presumably Utah chub, as the primary prey for otters occupying that lake (86%), while stable isotopes implicated brown trout (64%) over both lake trout and Utah chub (36% combined). Our data establish the importance of alternative prey to otters and suggest that lake trout-induced reductions in cutthroat trout may not be catastrophic for otter populations here. These data do not necessarily exonerate lake trout, as their impact on other species, most notably grizzly bears (Ursus arctos) and piscivorous birds, has been documented to be substantial, and further data on the nutritional value of alternate prey are required to confirm or refute a working hypothesis that otter populations will continue to thrive in the face of the lake trout invasion.     

An assessment of the behaviors of overwintering manatees as influenced by interactions with tourists at two sites in central Florida

We used a combination of focal animal and scan samples over the course of two winter seasons to assess behavioral patterns of manatees as a function of the presence and activities of recreational swimmers and boats in and around Crystal River National Wildlife Refuge, Florida. The nature and outcome of human-manatee interactions and the frequency of harassment of manatees by swimmers (as defined by the US Fish and Wildlife Service) were also recorded. The use of protected (no-entry) sanctuaries by manatees was significantly greater when both the numbers of swimmers and boats increased, and when water temperatures were lower in surrounding areas. The time manatees spent bottom-resting and nursing decreased while the time spent milling and swimming increased when swimmers were present compared with when they were absent. Over half of the direct interactions recorded between swimmers and manatees constituted some form of harassment as defined by Refuge guidelines, and manatees were far more likely to terminate these interactions than were swimmers. We conclude that the existence of no-entry sanctuaries is very important for the conservation of manatees in the area and thought must be given to expanding the sanctuary network. Furthermore, additional efforts at enforcement and public education are needed. We address, qualitatively, several potential management options to better-secure manatees at this critical time of the year.     

Sheld-geese and man in the Falkland Islands

The history of the association between sheld-geese (upland geese Chloëphaga picta and ruddy-headed geese C. rubidiceps) and man in the Falkland Islands is described from the time when they were used as food by early settlers, to the conflict with the sheep industry. Geese were found to be extremely abundant when man first settled. A bounty scheme was instigated by sheep farmers in 1905 and claimed 74 000 geese annually between 1905 and 1912. Far fewer (25 000 annually) were killed in the late 1970s because fewer shepherds lived in the remote houses of sheep stations, and the bounty did not increase in proportion with wage increases. The population of geese remains large despite this toll and recent studies of the annual cycle, movements and population dynamics give reasons for the failure of the bounty scheme to reduce numbers. Information on food intake and densities of geese on different vegetation types has indicated that the geese populations take only 1·5% of the total annual organic matter production of herbage. This represents 7% of what is eaten by all the herbivores. However, most of this consumption is restricted to a few vegetation types with a relatively small area (e.g. ‘greens’ and reseeded pastures). It is the consumption from reseeds that causes the biggest problem to the sheep industry. Methods of control are discussed and the value of destruction of geese questioned.     

Ecology of otters in Northern Scotland IV. A model scheme for otter Lutra lutra L. conservation in a freshwater system in aberdeenshire

Habitats for inclusion within otter havens are illustrated from a case-history study on the middle part of the Aberdeenshire River Dee. The environment is divided into breeding and rearing areas and places for non-breeding otters. One good location for a haven incorporating all three habitats includes 12–13 km of river and two nearly lochs. In this area, part of the river bank is inaccessible, and there are secluded islands and deep woods. Havens should include tiny tributaries leading to shelter where otters are likely to have their young. An otter haven in mid-Deeside planned to incorporate all these habitats may be regarded as a model for conservation that could be followed in other similar environments elsewhere.     

The biology of pastoral man as a factor in conservation

This paper discusses the basic relationship between the dietetic needs of pastoral people, the number of stock they must keep to supply these needs, and the productive capacity of the environment. While overgrazing and erosion in pastoral areas is usually attributed to ‘prestige’ overstocking, it is shown here that there is a basic minimum number of animals required to support a human family. This requirement is usually about 3 Standard Stock Units each of 500 kg live-weight per head, but varies from 2·5–4·5 according to the ecological conditions, and is made up of various classes of stock that are kept for meat or milk. Where rising human population becomes too great to permit each family to maintain this necessary minimum herd, damage to the environment through overstocking becomes inevitable. In addition, by competing for the available milk supply, the pastoral peoples inevitably starve the calves and depress the quality of their stock, especially where human populations are high. The prevalent ‘overgrazing’ situation is seen as one of human over-population in many areas—requiring the removal of humans, or alteration of their dietetic habits, as well as mere reduction of stock numbers. Possible methods of alleviating the situation include partial dependence on bought grain, or settlement on irrigation schemes, but none are easy or short-term.     

Zinc and copper toxicity in peanut,soybean, rice,and corn in soil mixtures

Abstract

Applications of zinc (Zn) and copper (Cu) at excessive rates may result in phytotoxicity. Experiments were conducted with mixtures of soils that were similar except for their Zn and Cu levels. The critical toxicity levels (CTL) in the soils and plants for these elements were determined. Peanut (Arachis hypogaea L.), soybean [Glycine max (L.) Merr.], corn (Zea mays L.), and rice (Oryza sativa L.) were the crops grown. One soil mixture had Mehlich 3‐extractable Zn concentrations up to 300 mg dm^‐3 with no corresponding increase in soil Cu; two soil mixtures had soil Zn concentrations up to 400 and 800 mg dm^‐3 with a corresponding increase in soil Cu up to 20 and 25 mg dm^‐3, respectively; and four soil mixtures had no increase in soil Zn, but had Mehlich 1‐extractable Cu concentrations from 6 to 286 mg kg^‐1. Under a given set of greenhouse conditions, the estimated Mehlich 3‐extractable Zn CTL was 36 mg dm^‐3 for peanut, 70 mg dm^‐3 for soybean, between 160 and 320 mg dm^‐3 for rice, and >300 mg dm^‐3 for corn. No soil Cu CTL was apparent for peanut or soybean, but for corn it was 17 mg dm^‐3 and for rice 13 mg dm^‐3. With different greenhouse procedures and the Mehlich 1 extractant, the soil CTL for rice was only 4.4 mg kg^‐1. Therefore, peanut and soybean were more sensitive to Zn toxicity, whereas corn and rice were more sensitive to Cu toxicity. Plant Zn CTL for peanut was 230 mg kg^‐1, while that for soybean was 140 mg kg^‐1. Copper appeared to be toxic to corn and rice at plant concentrations exceeding 20 mg kg^‐1.     

Chemistry, biochemistry, nutrition, and microbiology of lysinoalanine, lanthionine, and histidinoalanine in food and other proteins

Heat and alkali treatments of foods, widely used in food processing, result in the formation of dehydro and cross-linked amino acids such as dehydroalanine, methyldehydroalanine, beta-aminoalanine, lysinoalanine (LAL), ornithinoalanine, histidinoalanine (HAL), phenylethylaminoalanine, lanthionine (LAN), and methyl-lanthionine present in proteins and are frequently accompanied by concurrent racemization of L-amino acid isomers to D-analogues. The mechanism of LAL formation is a two-step process: first, hydroxide ion-catalyzed elimination of H(2)S from cystine and H(2)O, phosphate, and glycosidic moieties from serine residues to yield a dehydroalanine intermediate; second, reaction of the double bond of dehydroalanine with the epsilon-NH(2) group of lysine to form LAL. Analogous elimination-addition reactions are postulated to produce the other unusual amino acids. Processing conditions that favor these transformations include high pH, temperature, and exposure time. Factors that minimize LAL formation include the presence of SH-containing amino acids, sodium sulfite, ammonia, biogenic amines, ascorbic acid, citric acid, malic acid, and glucose; dephosphorylation of O-phosphoryl esters; and acylation of epsilon-NH(2) groups of lysine. The presence of LAL residues along a protein chain decreases digestibility and nutritional quality in rodents and primates but enhances nutritional quality in ruminants. LAL has a strong affinity for copper and other metal ions and is reported to induce enlargement of nuclei of rats and mice but not of primate kidney cells. LAL, LAN, and HAL also occur naturally in certain peptide and protein antibiotics (cinnamycin, duramycin, epidermin, nisin, and subtilin) and in body organs and tissues (aorta, bone, collagen, dentin, and eye cataracts), where their formation may be a function of the aging process. These findings are not only of theoretical interest but also have practical implications for nutrition, food safety, and health. Further research needs are suggested for each of these categories. These overlapping aspects are discussed in terms of general concepts for a better understanding of the impact of LAL and related compounds in the diet. Such an understanding can lead to improvement in food quality and safety, nutrition, microbiology, and human health.