Can lake sediments provide a record of tropical storms? The case of Laguna de Juanacatlan, Jalisco, Mexico [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Laguna de Juanacatlan is a small (15 hectare) lake in the State of Jalisco, Mexico. Its sediments are predominantly varved and thereby offer the potential of a high resolution paleoclimatic record.

Edad de la trucha arco iris (Salmo gairdneri) de la laguna Zeta (Prov.de Chubut)

Age of a population of rainbow trout (Salmo gairdneri) from a pond in Patagonia was studied by means of scale readings. The population was sampled three times, on December 1984, March 1985 and March 1986. Length at age was back-calculated from growth marks on scales, using the Fraser-Lee equation. By the analysis of length distributions and numbers of marks on scales from each sample, it was concluded that this population was formed by a single cohort, born in spring 1982 and stocked shortly after. Stocking rate is unknown. Significant differences (P0.05) were found between back-calculations of length at age 1 from samples of December 1984 and March 1986. These differences were probably due to length-scale radius relation. Evidences from scales suggested that a single mark is formed each year, during early-mid spring. On the other hand, according to availabe data from the literature for the same species, this population has presented one of the highest growth rates. (pdf contains 15 pages)

Paralelo biológico entre el pejerrey de la laguna de Lobos y el del Río de la Plata (zona frente a Cambaceres).

Estudio biológico comparativo de los pejerreyes de la laguna de Lobos y del Río de la Plata, provincia de Buenos Aires, Argentina. (PDF tiene 15 paginas.)

Apuntes ictiológicos de la laguna de Lobos (provincia de Buenos Aires).

Dentro del programa "Estudio hidrobiológico de la laguna de Lobos y su cuenca",se comprobó la presencia de 22 especies pertenecientes a 13 familias ubicadas en 6 órdenes.

El pejerrey de la laguna del Monte (Guaminí) en 1927-1928.

Entre las lagunas bonaerenses con pesca abundante del pejerrey, la de del Monte, en Guaminí, logró fama por su rendimiento extraordinario en determinados años, para luego decaer casi desapareciendo como fuente pesquera. En 1927 el gobierno provincial denunció el hecho de que "el pejerrey casi no crecía". Por esta causa, en ese año realicé estudios con tendencia a un planeamiento ecológico del problema pesquero y que repetí en 1928 cuando, según los pescadores, las condiciones de pesca eran más favorables. El hecho principal resultante es que, si bien el pejerrey de esa laguna no crecía más de 23 o 24 cm de longitud total, sus escamas exhibían 3 y 4 anillos, lo que indica otros tantos años de edad. Para esa edad, en otras lagunas el pejerrey es mucho más grande.

Some aspects of the ecology of the leatherback turtle Dermochelys coriacea at Laguna Jalova, Costa Rica

The ecology and reproductive biology of the leatherback turtle (Dennochelys coriacea) was studied on a high-energy nesting beach near Laguna Jalova, Costa Rica, between 28 March and 8 June 1985. The peak of nesting was between 15 April and 21 May. Leatherbacks here measured an average 146.6 cm straightline standard carapace length and laid an average 81.57 eggs. The eggs measured a mean 52.12 mm diameter and weighed an average of 85.01 g. Significant positive relationships were found between the carapace lengths of nesters and their clutch sizes and average diameter and weight of eggs. The total clutch weighed between 4.02 and 13.39 kg, and yolkless eggs accounted for an average 12.4% of this weight. The majority of nesters dug shallow (<24 cm) body pits and spent an average 81 minutes at the nest site. A significant number of c1utcbes were laid below the berm crest. In a hatchery 42.2% of the eggs hatched, while in natural nests 70.2% hatched. The average hatchling carapace length was 59.8 mm and weight was 44.6 g. The longevity of leatherback tracks and nests on the beach was affected by weather. One nester was recaptured about one year later off the coast of Mississippi, U.S.A. Egg poaching was intense on some sections of the Costa Rican coast. Four aerial surveys in four different months provided the basis for comparing density of nesting on seven sectors of the Caribbean coast of Costa Rica. The beach at Jalova is heavily used by green turtles (Chelonia mydJJs) after the leatherback nesting season. The role of the Parque Nacional Tortuguero in conserving the leatherback and green turtle is discussed.(PDF file contains 20 pages.)

The avifauna of Laguna Llancanelo (Mendoza, Argentina), a South American wetland of international importance

Laguna Llancanelo is a large (40,000 ha), very shallow (less than 3 m deep), inland saline waterbody, located in southern Mendoza, Argentina. A survey of the avifauna was undertaken during 1983 to 1985; field trips were made mostly to the northeastern and central-western sectors of the lagoon, in the months of April, May, September, October and December. Complementary studies were made by an aerial survey and assessments of terrestrial birds in the surroundings of the lagoon. A total of 64 species in 22 families of birds usually associated with aquatic environments were recorded. The best-represented families of aquatic birds in terms of numbers of species were: Anatidae (13 swans, geese, ducks), Scolopacidae (7 sandpipers and other small waders), Ardeidae (6 herons, bitterns, egrets, Podicipedidae (4 grebes), Rallidae (4 rails, coots) and Charadriidae (4 plovers, lapwings). The most abundant nesting birds on the lagoon were: Black-necked swan Cygnus melancoryphus (824), silvery grebe Podiceps occipitalis (202) and black-crowned night heron Nycticorax nycticorax (100).