Revista de biodiversidad y especies en peligro de extinción

A survey was conducted on the three gazetted landing beaches along the shores of Lake Naivasha by Kenya Marine and Fisheries Research Institute staff. The objectives of the study were to assess the existing knowledge and perception of the fisher community on the causes and impacts of the water hyacinth in Lake Naivasha and to identify and recommend possible solutions to control the hyacinth infestation. The study found that the fisher communities are very knowledgeable of the effect of the water hyacinth. Observing fish kills caused by oxygen depletion as a major impact of water hyacinth infestation which also impacted negatively on their socio- economic status. With fishing observed as their main occupation they recommended that the resource managers strive to stem Proliferation of the water hyacinth in order to create a viable condition for fishery production. Their hope of sustaining themselves economically would be made possible through participatory management approach in ensuring that the health of the lake’s ecosystem is kept in check.

Crassostrea virginica is notably known for its ability to create complex habitats known as oyster reefs. Oyster reefs provide the primary source of hard bottom habitat along the eastern seaboard
of the United States, yet natural reefs are absent from the Delaware Inland Bays. Oysters form reefs through a positive feed-back loop in which the shell matrix formed by resident oysters provides new substrate for the continual recruitment, settlement, and survival of successive generations. Shellfish beds trap and incorporate shells, sediment, algae, and other floating particles which provide a framework of material for tube-builders, bacteria, microalgae, invertebrates and other benthic species to live within. A variety of fauna utilize these structures for refuge and resource acquisition. Large oyster reefs are analogs to coral reefs, forests, salt marshes, and other habitats that perform critical ecosystem services.

Ten genotypes were tested for their adaptability study at five wheat growing areas of Tigray region, Northern Ethiopia. The elite varieties were arranged in RCB design with three replications. Data on grain yield was taken and subjected in to analysis of variance using Genstat 12 statistical software. Univariate stability analysis was also computed using different stability models. The combined analysis of variance showed that there were significant variations among genotypes, locations and their interaction. Based on grain yield, Mekelle-03 (3.24 t/ha) and FRET1 (3.15 t/ha) had scored the highest yield, while the local check yielded the least (2.35 t/ha). With respect to the univariate stability parameters, the different models identified the stability performance of the varieties. Based on the overall rank sum of stability parameters, the local check, M20ESWYT-46, Picaflor and FRET1were the most stable varieties, while HAR-1668, HAR-2501 and JEFERSON the least stable once. Since the tested varieties had shown differential yield responses across the environments, it is concluded that varietal recommendation should be based not only on overall mean yield, but also on their stability performance.

Two fresh water fish species Tilapia (Oreochromis mossambicus) and Common Carp (Cyprinus carpio) were cultured to investigate the survival rate in bioremediated sewage effluent of Shehzad town, Islamabad, Pakistan. Two earthen ponds one with fresh water and second with bioremediated sewage effluent, with dimension of 20×40 m were selected at Fisheries and Aquaculture Programme, NARC. Fish survival was investigated after fortnight sampling. Physicochemical parameters of bioremediated water were within permissible limit recommended for fish. Less than one percent survival was observed in bioremdiated water pond whereas 100% fish survival was recorded in fresh water pond. Further investigation and results showed the higher level of ammonical nitrogen (31.08 mg/L), nitrate nitrogen (18.58 mg/L) and chlorides (39.61 mg/L) in bioremediated sewage water that were main cause of fish mortality. Complete fish survival was recorded in bioremediated sewage effluent after phytoremediation with Coontail (Ceratophyllum demersum) plant that has potential of removing ammonia, nitrates and chlorides from sewage waste water. This study showed that this treated sewage water required further treatment for removal of ammonical- N, nitrate- N and chlorides by using phytoremdiater Coontail (Ceratophyllum demersum).

Abiotic and biotic variables of coastal lagoons are highly heterogeneous in both space and time, and this heterogeneity complicates the assessment of lagoon ecological status. These variables are essential for monitoring and preserving of these fragile ecosystems and the resources and services they sustain. This study was designed to assess the effect of lagoon water quality on changes in fish abundance. In situ measurements of chemical and physical parameters of the Batticaloa lagoons were measured fortnightly by using a calibrated portable Hanna instruments over the different seasons from March 2012 to February 2013. Fish diversity indices for the main commercial species were calculated. Fish composition varied greatly according to the study site and the seasonal trends. Results reveal that
the existing conditions, such as salinity dissolved oxygen, nitrate and pH had a strong effect on the fish community in the lagoon. The present study is commissioned to assess the seasonal variation and the status of the lagoon to make informed plans for the fishery of the lagoon patients to reap it successfully and sustainably.

Landscape structure is a key factor for biodiversity conservation. We assessed the potential role of landscaperelated habitat structure on Hazel Grouse (Tetrastesbonasia) by recording the occurrence of the species. Hazel Grouse is a widely recognized endangered species, because of the habitat loss as a direct consequence of land use change that is jeopardizing the species survival. The aim of this study is to provide a method based on habitat suitability modelling to explore and analyse hazel grouse- landscape structure and its relation to key habitat features. We evaluated landscape factors and critical threshold for monitoring the species, in order to assess the predictive power of models based on field
surveys, ancillary information and high resolution infrared aerial photographs. We tested Maximum Entropy (MaxEnt) algorithm, in order to predict the distribution of Hazel Grouse species, in the complex mountain landscape within the study site. This presence-only modelling method has showed numerous advantages over many other approaches. It is based on a function that links the fitness of individuals to their environment. Our results were highly consistent with field knowledge, showing that habitat modelling generated using spatial statistics and GIS can effectively help in the characterization of habitat requirements and the localization of the species suitable habitat. We found also that key drivers of Hazel Grouse distribution are not only environmental factors, in particular linked to elevation in mountain areas,
but also landscape heterogeneity is a key feature. Hence, conservation of this species will require land management practices that maintain heterogeneous landscape; in particular small forest openings are essential for the species. The approach developed seem to be a promising operational tool for local and regional managers interested in species monitoring and management within the long term.