In Victoria, Australia, both dryland salinity and salinity in irrigation regions are serious agricultural problems. One option to control the latter is to pump groundwater to maintain it below the surface. However, this leaves a saline wastewater for disposal, probably into local streams or wetlands. This review of the salt sensitivity of the biota of Australian streams and wetlands gives information of interest to those responsible for developing controls on these discharges. The review addresses the lethal and sub-lethal effects of salinity on microbes (mainly bacteria), macrophytes and micro-algae, riparian vegetation, invertebrates, fish, amphibians, reptiles, mammals, and birds. Data suggest that direct adverse biological effects are likely to occur in Australian river, stream and wetland ecosystems if salinity is increased to around 1 000 mg L−1. The review highlights a general lack of data on the sensitivity of freshwater plants and animals to salinity increases.

A review of the salt sensitivity of the Australian freshwater biota

Flying animals may experience a selective constraint on gut volume because the energetic cost of flight increases and maneuverability decreases with greater digesta load. The small intestine is the primary site of absorption of most nutrients (e.g., carbohydrates, proteins, fat) in both birds and mammals. Therefore, we used a phylogenetically informed approach to compare small intestine morphometric measurements of birds with those of nonflying mammals and to test for effects of diet within each clade. We also compared the fit of nonphylogenetic and phylogenetic models to test for phylogenetic signal after accounting for effects of body mass, clade, and/or diet. We provide a new MATLAB program (Regressionv2.m) that facilitates a flexible model‐fitting approach in comparative studies. As compared with nonflying mammals, birds had 51% less nominal small intestine surface area (area of a smooth bore tube) and 32% less volume. For animals <365 g in body mass, birds also had significantly shorter smal...

https://www.jstor.org/stable/10.1086/590395

Morphometrics of the avian small intestine compared with that of nonflying mammals: a phylogenetic approach.

In most animals, offspring from a reproductive bout usually hatch, emerge, or are born within a relatively short time of each other compared to the time required for their development Thus, hatching or birthing in most animals is synchronous This is especially likely to be true for animals with internal fertilization and development, where the birth of alll offspring occurs simultaneously (eg, some fihes, snakes, and most mammals) Synchronous reproduction also occurs in animals with external fertilization or development when all zygotes are subject to the same environmental conditions (eg, many insects, anurans, and fishes) Thus, in most the behavior of parents has little effect on the time between the emergence of their first and last young

Hatching Asynchrony and the Onset of Incubation in Birds, Revisited

The irrigation history of the San Joaquin Valley (Valley) is composed of several phases starting with individuals digging ditches and continuing to the present State Water Plan. Various institutions have developed to assist in the expansion of irrigation. These include the water companies ofthe last century and the water districts created by the Act of 1887. Irrigation has produced an enormous rise in the number of farms, population, and harvested acreage in the Valley. Agriculture in the Valley has changed over time. Initially it was cattle ranching with the prime product being the hides. Around the middle of the last century wheat production began and by the 1870's, following the arrival of the railroad, the Valley was a vast wheat land. Drought and reduced yields resulting from continual cropping began to reduce wheat acreage by the 1890's. This was accelerated by the expansion of irrigation and the increase of intensive agriculture. The major agricultural activities which have developed in the present century are: (1) Dairying, (2) vegetables, (3) orchard crops, and (4) cotton. These four activities accounted for about 82 percent of harvested land in 1987. The great expansion of irrigation was associated with the large increase in ground-water pumpage and the development of the Central Valley Project pumping northern California water to the Valley. The State Water Project now provides additional northern California water to the Valley. The expansion of irrigation has been accompanied by the rise of severe drainage problems which pose a significant threat to the future ofthe Valley. Continued ground-water pumpage is seriously depleting the region's ground-water basin and has produced land subsidence. The Valley's agricultural future is at risk due to: (1) The demand for water for higher valued uses such as municipal and industrial supplies; (2) the environmental need for additional freshwater to maintain the Sacramento!San Joaquin River Delta and San Francisco Bay Estuary; and (3) the necessity to solve the drainage problem. 10 BACKGROUND AND SETIING

The economics and management of water and drainage in agriculture.

Avian integument is thin, elastic, and loosely attached to the body, giving birds the freedom of movement needed for flight. Its epidermis is both keratinized and lipogenic, and the skin as a whole acts as a sebaceous secretory organ. The skin is covered by feathers over most of the body, but many birds show colored bare skin or integumentary outgrowths on the head and neck. Heavily cornified epidermis covers the beak, claws, spurs, and the scales on the legs and feet. These structures (except the back of the leg and underside of the foot) contain beta-keratin like that in reptilian scales. Most birds have sebaceous secretory glands at the base of the tail and in the ear canals. Feathers are the most numerous, elaborate, and diverse of avian integumentary derivatives. Their diversity is due to the possibilities inherent in their basic plan of a shaft with two orders of branches and the use of modified beta-keratin as a strong, light, and plastic building material. The evolution of feathers in birds has been accompanied by the development of complex systems for producing colors and patterns, the innovations of feather arrangement and follicles with their musculature and innervation, and the process and control of molting.

The Integumentary Morphology of Modern Birds—An Overview1

Wilson’s Phalaropes (Phalaropus tricolor) and American Avocets (Recurvirostra americana) occur in large numbers at hypersaline and alkaline lakes. Comparing birds from three lakes of different salinity and alkalinity in the Great Basin of western North America, we found no evidence of salt-loading: blood hematocrit, pH, osmolality, and sodium concentration were not elevated; stomach osmolality and sodium concentration were only slightly higher than the body fluids of the birds’ hypo-osmotic prey (brine shrimp and brine flies); salt glands were not enlarged and averaged a relatively low percentage of body weight (0.02%). Through a combination of behavioral and anatomical adaptations, phalaropes and avocets evidently are able to rid their prey of most adherent lake water and thereby largely avoid the problems of salt-loading and the ingestion of harmful ions. Both species occupy hypersaline habitats for long periods and probably derive most of their water needs from the body fluids of their prey. Their use of fresh water is sporadic and may not be required for osmoregulatory balance. Alkaline and hypersaline lakes, despite being harsh physical environments, are prime habitats for a few species of resident (e.g., flamingos) and a somewhat larger number of migratory waterbirds. Mono Lake, California, a large hypersaline (2’ 12 x the concentration of sea water) and alkaline (pH x 10) lake at the eastern base of the Sierra Nevada, attracts large numbers of a few of these species each year. Approximately 45,000 California Gulls (Larus californicus) nest there; in summer and in fall, tens of thousands of Wilson’s (Phalaropus tricolor) and Red-necked (P. lobatus) phalaropes stop over on their southward migration (Jehl 198 l), and hundreds of thousands of Eared Grebes (Podiceps nigricollis) stage there (Storer and Jehl 1985). American Avocets (Recurvirostra americana) are also common at hypersaline lakes, although at Mono Lake only a few pairs breed and flocks of several hundred occur in autumn. Hypersaline lakes are attractive to these birds because they typically lack fish, which allows the few invertebrates that can occupy them to attain great abundances. These, in turn, serve as food for the birds. At Mono Lake, brine shrimp (Artemia sp.) and brine flies (Ephydru hians) become super-abundant at some seasons. Birds feeding on these invertebrates, either by pecking them from the surface of the water or by catching them while driving, might be expected to ingest large amounts of lake water and thereby incur deleterious salt loads. Yet, our previous studies of California Gulls (Mahoney and Jehl 1985a) and Eared Grebes (Mahoney and Jehl 1985b) at Mono Lake, where salinities have varied from 72 to 90 ppt (2,160-2,700 mOsm/kg) in 1982-l 984, have shown that this is not the case. These species seem to have no special anatomical or physiological adaptations for dealing with high salt loads. Instead, they largely avoid osmoregulatory problems behaviorally, by ridding their food of adherent lake water before swallowing it. Gulls and grebes differ markedly in their use of fresh water. Gulls visit freshwater streams to drink and bathe several times each day, whereas grebes, although they may remain continuously at Mono Lake for as long as six months (Jehl, unpubl. data), never visit fresh water. Wilson’s Phalaropes and American Avocets (Fig. 1) have intermediate patterns of water use; both visit fresh water regularly, though probably not daily. If phalaropes and avocets ingest large quantities of Mono Lake water and its attendant osmotic and ionic load, they could be expected to show changes in blood chemistry, hydration state, and salt gland size. In order to determine how great a salt load these birds incur while feeding at the lake, we made the following measurements: blood pH and hematocrit; serum osmolality, sodium, and potassium; composition and osmolality of stomach contents, prey body fluids, and lake water; body water content; and salt gland weights. We then compared these values from Mono Lake birds to those

/pdf/adaptations-of-migratory-shorebirds-to-highly-saline-and-3uk6ytccoi.pdf

Adaptations of Migratory Shorebirds to Highly Saline and Alkaline Lakes: Wilson’s Phalarope and American Avocet

Body mass, intestinal lengths, and the occurrence and relative size of ceca from 154 species of birds representing 21 orders and a diversity of food habits were com- pared. Well-developed ceca occur in the Anseriformes, Galliformes, Gruiformes, Cuculifor- mes, Strigiformes, Caprimulgiformes, and Trogoniformes. The presence of well-developed ceca is less consistent in other orders and appears to be related to diet; herbivorous species whose diets contain large amounts of cellulose have well-developed ceca, whereas species having diets rich in soluble sugars and proteins tend to have poorly-developed or no ceca. We postulate that the relatively well-developed ceca in some non-herbivorous birds are associated with conservation of critical resources such as water and nitrogen.

https://www.jstor.org/stable/info/1370192

Relationships of avian cecal lengths to food habits, taxonomic position, and intestinal lengths

Avoidance of Salt-Loading by a Diving Bird at a Hypersaline and Alkaline Lake: Eared Grebe

http://academic.oup.com/auk/article-pdf/101/1/181/30079816/auk0181.pdf

Plumage wettability of aquatic birds

Behavioral and physiological research were combined to determine how California gulls (Larus californicus) are able to survive and breed at Mono Lake, California, a lake that is two and one-half times more concentrated (2,400 mOsm kg⁻¹) than seawater and contains high concentrations of sulfates and carbonates as well as sodium and chloride. Adults avoided salt loading by (1) taking in very little lake water along with brine shrimp (and brine flies) they obtained from the lake and (2) visiting freshwater sources along the shore. Their stomach contents averaged 466 mOsm kg⁻¹, slightly more dilute than the salt concentration of brine shrimp (~500 mOsm kg⁻¹). Stomach contents of chicks and fledglings averaged 636 and 651 mOsm kg⁻¹, respectively. Hematocrits, serum osmolality, serum sodium and potassium, and body-water content of adults, chicks, and fledglings were similar to those of other birds and indicated neither salt loading nor dehydration. Salt glands of adults and chicks were not hypertrophied. Experi...

Sheila A. Mahoney

Papers

Adaptations of Migratory Shorebirds to Highly Saline and Alkaline Lakes: Wilson’s Phalarope and American Avocet

Relationships of avian cecal lengths to food habits, taxonomic position, and intestinal lengths

Avoidance of Salt-Loading by a Diving Bird at a Hypersaline and Alkaline Lake: Eared Grebe

Plumage wettability of aquatic birds

Physiological ecology and salt loading of California gulls at an alkaline, hypersaline lake