This paper provides the location, scenery and litter evaluation of 35 Colombian Caribbean beaches (9 remote, 9 village, 14 urban and 3 resort). Four litter grades were found. A: excellent (5); B: good (8); C: fair (19) and D: poor (3). A Decision Value parameter (D), for scenery gave: Class I-extremely attractive/natural, D > 0.85, 6 sites; Class II-attractive/natural sites, D = 0.85-0.65, 2 sites; Class IIImainly natural sites, few outstanding features, D = 0.65-0.4, 1 site; Class IV-mainly unattractive sites, D = 0.4 to zero, 6 sites; Class V-very unattractive sites, D = <0, 20 sites. Litter amounts placed most beaches into a poor scenic category and many scenic beaches could jump a grade by means of clean-ups. A graphic methodology highlighted beaches with contradictory results for litter/scenic grades. Tourists abhor littered beaches and clean-ups would improve scenery scores.

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Four beaches that share physiographic characteristics (sandy, wide, and long) but differ in socioeconomic and cultural terms (three are located in northwestern Mexico and one in California, USA) were evaluated by beach users. Surveys (565) composed of 36 questions were handed out to beach users on weekends and holidays in 2005. The 25 questions that revealed the most information were selected by factor analysis and classified by cluster analysis. Beach users' preferences were assigned a value by comparing the present survey results with the characteristics of an "ideal" recreational urban beach. Cluster analysis separated three groups of questions: (a) services and infrastructure, (b) recreational activities, and (c) beach conditions. Cluster linkage distance (r=0.82, r=0.78, r=0.67) was used as a weight and multiplied by the value of beach descriptive factors. Mazatlán and Oceanside obtained the highest values because there are enough infrastructure and services; on the contrary, Ensenada and Rosarito were rated medium and low because infrastructure and services are lacking. The presently proposed method can contribute to improving current beach evaluations because the final score represents the beach users' evaluation of the quality of the beach. The weight considered in the present study marks the beach users' preferences among the studied beaches. Adding this weight to beach evaluation will contribute to more specific beach planning in which users' perception is considered.

Phytoplankton blooms are sporadic events in time and are isolated in space. This complex phenomenon is produced by a variety of both natural and anthropogenic causes. Early detection of this phenomenon, as well as the classification of a water body under conditions of bloom or non-bloom, remains an unresolved problem. This research proposes the use of Inherent Optical Properties (IOPs) in optically complex waters to detect the bloom or non-bloom state of the phytoplankton community. An IOP index is calculated from the absorption coefficients of the colored dissolved organic matter (CDOM), the phytoplankton (phy) and the detritus (d), using the wavelength (λ) 443 nm. The effectiveness of this index is tested in five bloom events in different places and with different characteristics from Mexican seas: 1. Dzilam (Caribbean Sea, Atlantic Ocean), a diatom bloom (Rhizosolenia hebetata); 2. Holbox (Caribbean Sea, Atlantic Ocean), a mixed bloom of dinoflagellates (Scrippsiella sp.) and diatoms (Chaetoceros sp.); 3. Campeche Bay in the Gulf of Mexico (Atlantic Ocean), a bloom of dinoflagellates (Karenia brevis); 4. Upper Gulf of California (UGC) (Pacific Ocean), a diatom bloom (Coscinodiscus and Pseudo-nitzschia) and 5. Todos Santos Bay, Ensenada (Pacific Ocean), a dinoflagellate bloom (Lingulodinium polyedrum). The diversity of sites show that the IOP index is a suitable method to determine the phytoplankton bloom conditions.

Th e study focuses on the environmental problem of diff use pollution from agriculture (DPA) as a result of the land use and the policy intervention that can be used to mitigate the problem. Attention is paid to the use of economic instruments (EIs) in policies concerning the DPA. Also, policy options, the advantages and disadvantages of the EIs and their assessment are looked at.