Differences in Evaporation Between a Floating Pan and Class A Pan on Land1

Abstract: Research was conducted to develop a method for obtaining floating pan evaporation rates in a small (less than 10,000 m²) wetland, lagoon, or pond. Floating pan and land pan evaporation data were collected from March 1 to August 31, 2005, at a small natural wetland located in the alluvium of the Canadian River near Norman, Oklahoma, at the U.S. Geological Survey Norman Landfill Toxic Substances Hydrology Research Site. Floating pan evaporation rates were compared with evaporation rates from a nearby standard Class A evaporation pan on land. Floating pan evaporation rates were significantly less than land pan evaporation rates for the entire period and on a monthly basis. Results indicated that the use of a floating evaporation pan in a small free‐water surface better simulates actual physical conditions on the water surface that control evaporation. Floating pan to land pan ratios were 0.82 for March, 0.87 for April, 0.85 for May, 0.85 for June, 0.79 for July, and 0.69 for August.     

Using Participatory Rural Appraisal to explore coastal fishing in Badagry villages,Nigeria

Fish production and marketing are as old as the rural communities involved in the lucrative occupation in Badagry area of Lagos State, Nigeria. A random sampling of 200 fishermen using Participatory Rural Appraisal techniques (PRA) in five Badagry villages was used to explore coastal fishing and socio-economic development in the study area with a view to enhancing local productivity and sustainability. The findings show that an average fisherman in Badagry is aware of the resources available in his environment, and can affect productivity levels positively if given adequate incentives. There are two lessons from this study; one has to do with what PRA tells us about the fishing community, the other is the importance of facilitators that have, amongst other things, good listening skills. The experience also revealed that field workers’ ability to listen and learn from local fishermen was a critical factor in collecting in-depth information that could be used for rural community planning.     

The Great Lake’s future at a cross road

Some argue that a collective vision for the future of the Laurentian Great Lakes is embodied in the␣Great Lakes Water Quality Agreement (GLWQA). The GLWQA is a binational agreement, first signed in 1972 by Prime Minister Pierre Trudeau and President Richard Nixon, wherein the two countries (the Parties) commit to “restore and maintain the chemical, physical and biological integrity of the waters of the Great Lakes Basin Ecosystem.” Article X of the Agreement states that the Parties shall conduct a comprehensive review of the operation and effectiveness of this Agreement following every third biennial report of the [International Joint] Commission (IJC). The IJC’s 12th Biennial Report, released in 2004, triggered this important science, program, and policy review which commenced May 2006. This essay makes the case for a rigorous review, that explores deliberately the future scope of the Agreement to protect the world’s largest surface freshwater resource, and calls for innovation in the governance regime of this binational ecosystem.     

Redwood of the reef: growth and age of the giant barrel sponge Xestospongia muta in the Florida Keys

The growth of animals in most taxa has long been well described, but the phylum Porifera has remained a notable exception. The giant barrel sponge Xestospongia muta dominates Caribbean coral reef communities, where it is an important spatial competitor, increases habitat complexity, and filters seawater. It has been called the ‘redwood of the reef’ because of its size (often >1 m height and diameter) and presumed long life, but very little is known about its demography. Since 1997, we have established and monitored 12 permanent 16 m diameter circular transects on the reef slope off Key Largo, Florida, to study this important species. Over a 4.5-year interval, we measured the volume of 104 tagged sponges using digital images to determine growth rates of X. muta. Five models were fit to the cubed root of initial and final volume estimates to determine which best described growth. Additional measurements of 33 sponges were taken over 6-month intervals to examine the relationship between the spongocoel, or inner-osculum space, and sponge size, and to examine short-term growth dynamics. Sponge volumes ranged from 24.05 to 80,281.67 cm³. Growth was variable, and specific growth rates decreased with increasing sponge size. The mean specific growth rate was 0.52 ± 0.65 year⁻¹, but sponges grew as fast or slow as 404 or 2% year⁻¹. Negative growth rates occurred over short temporal scales and growth varied seasonally, significantly faster during the summer. No differences in specific growth rate were found between transects at three different depths (15, 20, 30 m) or at two different reef sites. Spongocoel volume was positively allometric with increasing sponge size and scaling between the vertical and horizontal dimensions of the sponge indicated that morphology changes from a frustum of a cone to cylindrical as volume increases. Growth of X. muta was best described by the general von Bertalanffy and Tanaka growth curves. The largest sponge within our transects (1.23 × 0.98 m height × diameter) was estimated to be 127 years old. Although age extrapolations for very large sponges are subject to more error, the largest sponges on Caribbean reefs may be in excess of 2,300 years, placing X. muta among the longest-lived animals on earth.     

Ephemeral spawning aggregations in the Mediterranean sardine, <Emphasis Type=Italic>Sardina pilchardus</Emphasis>: a comparison with other multiple-spawning clupeoids

Using previously published histological data on multiple, monthly samples of Sardina pilchardus collected in the central Aegean and Ionian Seas (September 1999–August 2000, and November 2000–February 2001), the Mediterranean sardine was treated as a case study to investigate the biological characteristics of ephemeral spawning aggregations in multiple-spawning clupeoids. Actively spawning (Day₀) females in the Mediterranean sardine, i.e., the daily class of spawners caught a few hours prior, during, or after the spawning act, were shown to separate spatially from late (Day₁₊) spawners and non-spawning females, taking with them a large proportion of conspecific males which were also in advanced spawning condition and in better somatic condition compared to the remaining population. In addition, information from 28 stocks of multiple-spawning clupeoids from a wide range of geographic locations, belonging to 14 species and 2 families (Engraulidae and Clupeidae), was reviewed and analyzed pertinent to the formation of ephemeral spawning aggregations. Results from the latter analysis indicated similar patterns of spatial segregation of Day₀ spawners in the reviewed clupeoid stocks as in the Mediterranean Sardine, which strongly suggested that the formation of ephemeral spawning aggregations is a common behavioral trait among multiple-spawning clupeoids. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The interrelationships between resource-holding potential,resource-value and reproductive success in territorial males: How much variation can we explain?

A long-standing hypothesis in behavioural ecology posits that males with greater resource-holding potential (RHP) control resource sites deemed more valuable by sexually-receptive females and, thereby, males controlling such sites accrue greater reproductive success (RS). This hypothesis has historically been investigated using three separate but non-mutually exclusive relationships (male RHP vs. resource value, resource value vs. male RS and male RHP vs. RS). The relationships between these three variables are predicted to be strongly positive, however, due to measurement error and biological noise, perfect correlations (r = 1.0) are rare in biology even for well-established relationships. Moreover, the inaccurate identification of either the male trait(s) important to RHP or the resource characteristic sought by females will weaken the observed strength of the relationships. Here, I use meta-analysis to quantitatively describe the general pattern of these relationships in animals. I predict that the relationships between male RHP, resource-value and RS should be significantly positive (male RHP and resource-value should explain a large amount of the variation in male RS). My meta-analysis supports this hypothesis; however, in the best case scenario only ca. 20% of the variation in the response variable was explained. I conclude by identifying areas in which we need to improve our investigations of resource-defence animals and recommending approaches to meet these needs. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.