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.)

Ikas-Komunitateak: solasaldi dialogiko literarioak eta irakur-laguna, Etxebarriko Kukullaga eskolan.

[EUS] Egungo informazioaren gizartean, etengabeko aldaketa sakonak jasaten eta sortzen ditugu, halaber gure gizabanako harremanetan ere. Hala ere, hezkuntzak oraindik ez du aldaketa handirik egin, izan ere, nahiko estatikoa izaten jarraitzen du eta bertan ematen diren harremanak zeharo hierarkikoak dira. Honengatik guztiagatik, ikerketa honen xede nagusia, Ikas-Komunitateak eta honen barruan dagoen Etxebarriko KUKULLAGA LHI (Bizkaia) aztertzea izango da. Horrez gain, eskolarekin batera diseinatu dudan proiektua aurkeztuko dut, zeinean Ikas-Komunitateen bi jarduera burutzen diren: irakur-laguna eta solasaldi dialogiko literarioak. Bertan, Lehen Hezkuntzako 6. mailako eta 5 urteko ikasleek parte hartu dute. Aipatzekoa da lortutako emaitzak guztiz baikorrak izan direla eta epe-laburrerako ezarritako helburuak lortu direla. Horrez gain, epe-luzerako helburuak hein handi batean beteko direla aurreikusten da. Beraz, argi dago, zentroetan antolakuntza egoki bat ematen bada, Ikas- Komunitateen proiektuarekiko inplikazioa badago eta komunitatearen kohesioa lortzen bada, hezkuntza sistema hein batean alda daitekeela. Hori gertatuz gero, edozein motatako pertsonak hezkuntza emaitzarik onenak lor ditzake eta baita informazioaren gizarte honetan jarduten ikas dezake ere.

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).