Anàlisi i diagnosi ambiental de la dinàmica del porc senglar (Sus scrofa) al Parc del Garraf

El Parc del Garraf (PG) és una zona on la dinàmica del porc senglar amb el medi té una alta importància, tot i que la densitat de població al PG d’aquest ungulat és de les menors de Catalunya. Els aspectes més rellevants de la relació porc senglar-medi són: la correlació que hi ha entre l’abandonament d’àrees de conreu i activitats forestals amb l’augment de la població de porc senglar, i l’afectació que per tant, provoca a les àrees de conreu que hi ha actualment, que es pot veure minvada aplicant bones mesures correctores. També la relació que té amb el margalló (Chamaerops humilis), que és positiva ajudant a la recuperació, conservació i a la dinàmica ecològica de l’espècie, així com amb el medi del PG en general, i, per últim, els impactes viaris a la xarxa viària del PG, tot i que no existeix cap TCCU (Tram de Concentració de Col·lisions amb Ungulats) dins els límits del PG. Referent a la caça, actualment és la única mesura viable de control de la població de porc senglar, tot i que no hi ha relleu generacional per a aquesta activitat.

Béns i serveis associats als ecosistemes de fanerògames marines i estimacions de pèrdues causades per la seva degradació

Les praderies de posidònia de la costa catalana són ecosistemes d’alta importància, ja que tenint en compte la seva poca extensió, ens aporten una gran multiplicitat de béns i serveis ecosistèmics. No obstant, els danys observats en els prats en les últimes dècades, tant pel que fa a la regressió en superfície com a la pèrdua d’integritat ecològica, ens indiquen que aquests ecosistemes s’estan enfrontant a una crisi causada principalment per les pressions de les activitats antròpiques a les zones costaneres. En aquest projecte es pretenen identificar tots els béns i serveis que ens proporcionen aquests herbeis, així com també dictaminar quina és la importància de cada un d’ells en el context de la costa catalana. D’altra banda, es pretenen avaluar els impactes i conseqüències de la seva degradació i també quantificar, de manera relativa, la pèrdua d’aquests béns i serveis a la costa catalana, partint de la base que, segons els resultats obtinguts, la pèrdua d’abundància en els prats ha estat d’aproximadament el 60% des d’un hipotètic estat “pre-industrial” fins l’actualitat.

Evolució de la vegetació de l’antic estany de Sils (la Selva) en els darrers 50 anys

The historical evolution of vegetation in the former Sils Pond (la Selva) during the second half of the 20th century is described through the study of past(Bolòs, 1954; Vilar, 1981) and present-day (Mercadal, 2002) vegetation cartography, the first aerial photographs (1956 and 1980) and current orthophotos (2000). This inland pool was finally drained in 1851 and most of its area was converted into meadows (Gaudinio fragilis-Arrhenatheretum elatioris Br.-Bl. in Br.-Bl., Roussine & Nègre 1952), a semi cultural community which was very distinct florally, for the Mediterranean region. The results demonstrate that in the last 50 years changes in land use have transformed the former landscape, which was prominently meadow-like and grain-producing, into woodlands, wet grasslands, developed areas and sub-Mediterranean forests, with the consequent loss of meadow areas and floristic diversity. In response, based on historical cartography, we propose spaces to prioritize for recovery and management such as meadow areas

Experimental evidence that intra-specific competition in seagrass meadows reduces reproductive potential in the sea urchin Paracentrotus lividus (Lamarck)

To better understand the biological controls that regulate sea urchin dynamics, we studied the effects of potential inter- and intra-specific competition for food on several biological variables of the main sea urchin in the Mediterranean (Paracentrotus lividus). We carried out a caging experiment in which we manipulated sea urchin density (natural vs. high density) and herbivorous fish (Sarpa salpa) accessibility (free access vs. exclusion) in a Posidonia oceanica meadow. No evidence of competition between fish and urchins was detected. Neither density-dependent mortality nor changes in the somatic variables were found; however, we detected that intra-specific competition affected the reproductive potential of P. lividus. The gonad index of urchins at high population densities was ca. 30% lower than that of urchins at natural densities. As a spawning event had just occurred when urchins were collected, these differences probably reflect differences in reserve content, which may compromise the following reproductive period and decrease survival in the long term, as the gonads are also used as storage organs. For the time period studied, mortality rates appeared to be independent of local densities. The results indicate that a long-term negative feedback mechanism appears to take place in P. lividus in response to increased population density.

La necrópolis de Cozzo delle Giummare (Noto Sicacrisa, Sicilia oriental)

La necrópolis del Cozzo delle Giummare y la de la Grotta del Murmuro, situadas en las laderas del Monte Finocchito, pertenecen a dos pequeños caseríos del arrabal. Fueron descubiertas por Paolo Orsi a pocos kilómetros de la cumbre del monte - donde estaba asentada la ciudad rodeada de la vasta necrópolis del Finocchito-, precisamente en las laderas meridionales junto a las que transcurre el río Tellaro. Orsi las consideró como necrópolis dependientes de la misma ciudad y estaba convencido de que pertenecían a idéntica época que aquélla, por dos razones fundamentales: a} Estaban separadas de la ciudad por 3 o 4 km. únicamente. b} La mayoría de los materiales de estos cementerios pueden englobarse dentro de la llamada Civilización o Cultura del Finocchito (730-650 a. de J. C.). La necrópolis del Cozzo delle Giummare, denominada así por la Chamerops humilis, que crece allí frecuentemente, ocupa la parte extrema de un contrafuerte poco ondulado. Consta de treinta sepulturas relacionadas con un pequeño hábitat que debía existir en una planicie situada a mayor altura, la cual dista 2,5 km. de la cúspide de la montaña. Orsi, a través de un examen superficial de las sepulturas, creyó que pertenecían a la cultura de Casteluccio (primer período de Orsi); sin embargo, no sabía cómo conciliar con esta hipótesis la presencia de pequeños bronces típicos de la fase IV de Pantálica (tercer período de Orsi), recogidos en el mismo lugar por algunos pastores . . Mediante las excavaciones, Orsi descubrió un hecho nuevo: los sepulcros de la época de Casteluccio, con sus esqueletos y sus ajuares parcial o enteramente conservados, fueron reutilizados después de muchos siglos por gentes contemporáneas de los constructores del poblado y la necrópolis del Finocchito.

Experimental evidence that intra-specific competition in seagrass meadows reduces reproductive potential in the sea urchin Paracentrotus lividus (Lamarck)

To better understand the biological controls that regulate sea urchin dynamics, we studied the effects of potential inter- and intra-specific competition for food on several biological variables of the main sea urchin in the Mediterranean (Paracentrotus lividus). We carried out a caging experiment in which we manipulated sea urchin density (natural vs. high density) and herbivorous fish (Sarpa salpa) accessibility (free access vs. exclusion) in a Posidonia oceanica meadow. No evidence of competition between fish and urchins was detected. Neither density-dependent mortality nor changes in the somatic variables were found; however, we detected that intra-specific competition affected the reproductive potential of P. lividus. The gonad index of urchins at high population densities was ca. 30% lower than that of urchins at natural densities. As a spawning event had just occurred when urchins were collected, these differences probably reflect differences in reserve content, which may compromise the following reproductive period and decrease survival in the long term, as the gonads are also used as storage organs. For the time period studied, mortality rates appeared to be independent of local densities. The results indicate that a long-term negative feedback mechanism appears to take place in P. lividus in response to increased population density.

Temporal variation of the biomass and structure of Caulerpa prolifera (Forsskal) Lamouroux meadows in the Mar Menor lagoon (SE Spain).

The temporal changes in the structure, biomass and C, N and P content of meadows of Caulerpa prolifera (Forsskal) Lamouroux in the Mar Menor coastal lagoon (SE Spain) are described over the period from November 1986 to March 1989. C. prolifera meadows showed a unimodal pattern of vegetative development with maximum biomass values (168-173 g d.w. m-2) reached in summer and maintained during autumn, and minimum biomass values (0-57 g d.w. m-2) during late winter and early spring. Leaf area index values changed between 0.37-0.40 m2 m-2 in January-February and 2.60-7.06 m2 m-2 in July. The seasonality in the biomass and structure of the meadow was mainly related to the vegetative development of the secondary fronds. Carbon and phosphorus content of the thallus (32.5-34.8% d.w. and 0.065-0.069% d.w., respectively) had no seasonality, but nitrogen content showed a bimodal annual pattern with higher values in spring and fall (>2.5% d.w.) than in summer and winter (<2.5% d.w.).

Brook Trout Removal as a Conservation Tool to Restore Eagle Lake Rainbow Trout

Nonnative brook trout Salvelinus fontinalis are abundant in Pine Creek and its main tributary, Bogard Spring Creek, California. These creeks historically provided the most spawning and rearing habitat for endemic Eagle Lake rainbow trout Oncorhynchus mykiss aquilarum. Three-pass electrofishing removal was conducted in 2007–2009 over the entire 2.8-km length of Bogard Spring Creek to determine whether brook trout removal was a feasible restoration tool and to document the life history characteristics of brook trout in a California meadow stream. After the first 2 years of removal, brook trout density and biomass were severely reduced from 15,803 to 1,192 fish/ha and from 277 to 31 kg/ha, respectively. Average removal efficiency was 92–97%, and most of the remaining fish were removed in the third year. The lack of a decrease in age-0 brook trout abundance between 2007 and 2008 after the removal of more than 4,000 adults in 2007 suggests compensatory reproduction of mature fish that survived and higher survival of age-0 fish. However, recruitment was greatly reduced after 2 years of removal and is likely to be even more depressed after the third year of removal assuming that immigration of fish from outside the creek continues to be minimal. Brook trout condition, growth, and fecundity indicated a stunted population at the start of the study, but all three features increased significantly every year, demonstrating compensatory effects. Although highly labor intensive, the use of electrofishing to eradicate brook trout may be feasible in Bogard Spring Creek and similar small streams if removal and monitoring are continued annually and if other control measures (e.g., construction of barriers) are implemented. Our evidence shows that if brook trout control measures continue and if only Eagle Lake rainbow trout are allowed access to the creek, then a self-sustaining population ofEagle Lake rainbow trout can become reestablished