Ontogenetic habitat and dietary shifts in Japanese turban snail <Emphasis Type="Italic">Turbo cornutus</Emphasis> at Nagai,Sagami Bay,Japan

A field survey and a laboratory experiment were conducted to examine ontogenetic shifts in habitat and diet of the turban snail Turbo cornutus. The main habitat of turban snail juveniles smaller than 10 mm shell height (SH) was turfs of articulated coralline algae, and that of adults larger than 50 mm SH was kelp beds of Ecklonia bicyclis and Ecklonia cava. However, the ontogenetic habitat shift during the juvenile stage of 20–50 mm SH was unclear. From the results of a long-term feeding experiment and stable isotope analysis, the gelidiacean alga Gelidium elegans was assumed to be more important as a food source for juvenile turban snail than E. cava in the field. However, the frequency of individuals inhabiting gelidiacean algal turfs was low in both juvenile and adult stages. Thus, the ontogenetic shifts in habitat and diet did not coincide and other factors, i.e., daytime refuge, are important. As the growth rate was higher in the juveniles fed on the two algal species than those fed on single algal species, co-occurrence of various algal habitats in rocky shore ecosystems as a coastal ecosystem complex may enhance growth of turban snail juveniles feeding on a combination of different algal species.     

Feeding rate responses of Babylonia formosae habei (Prosobranchia: Buccinidae) larvae on cultured algae

Babylonia formosae habei is a commercially important marine gastropod species. Food particles ingested by the planktotrophic larvae of B. formosae habei can be critical in maximizing the larval growth and survival of this species. In this study, feeding rate responses of B. formosae habei larvae on cultured algae were observed using a Coulter multisizer. Variations were recorded based on the changes of different factors of influence, including varied larval stoking density, varied types of algae, varied algae concentrations and selective feeding on mixed algae cells of different types. Results of this study reveal some facts on the feeding of B. formosae habei larvae: larval stoking density has negative effect on their feeding rates; larva has a higher feeding rate on big‐sized algae than small‐sized algae; larva has a higher feeding rate on diatom than green algae and flagellate; feeding rate of larvae increased when fed mixed algae cells. Optimal algal concentration of the cultured algae Chlorella sp., Chaetoceros muelleri, Isochrysis zhanjiangensis and Dunaliella tertiolecta was suggested at 20 × 10⁴, 5 × 10⁴, 20 × 10⁴ and 10 × 10⁴ cells mL^?1 respectively. Results of the preset study can be important in understanding feeding ecology of B. formosae habei larvae, and applicable for the aquaculture of this species.     

Community and trophic structures of abalone <Emphasis Type="Italic">Haliotis diversicolor</Emphasis> habitat in Sagami Bay,Japan

Abstract:   The community and trophic structures of the subtidal habitat of the abalone Haliotis diversicolor were examined in Nagai, Sagami Bay, Japan. Conventional community indices showed no significant differences among three sampling stations. The overall continuum of stable isotope ratios was structured into three different trophic linkages: (i) brown algae-dependent benthic food chain; (ii) red algae-dependent benthic food chain; and (iii) planktonic food chain. Brown algae and red algae likely play different roles with respect to carbon sources in the habitat. Conventional fractionation values indicated that the abalone H. diversicolor (δ¹³C = −12.4 ± 1.0‰, δ¹⁵N = 9.3 ± 0.5‰) feeds on the lamina of Undaria pinnatifida during juvenile and adult stages (8.0–65.6 mm shell length). Stable isotope signatures suggested that the juveniles of other abalone species as well as some amphipods and a sea cucumber Holothuria decorata are competitors of H. diversicolor , whereas some Muricidae gastropods such as Thais bronni and Ergalatax contractus are predators. The isotopic differences among macroalgal species and the subsequent transfer to consumers indicate that stable isotopic analysis is an effective means of studying food webs in an open rocky shore community with little influence from external primary production such as terrestrial vegetation.     

The trophic cascade from fish to benthic algae: manipulation of habitat heterogeneity and disturbance in experimental flow-through pools

To investigate the effects of environmental change on the trophic cascade from fish to benthic algae, two 26-day experiments were conducted in outdoor flow-through pools. Habitat heterogeneity was manipulated by filling grooves under tiles with wood. Disturbance was simulated by removing invertebrates and benthic algae from tiles with a stainless steel brush 10 days before the end of the experiment. Benthic invertebrates and algae rapidly colonized the pools. Japanese dace Tribolodon hakonensis that had been introduced as a top predator fed predominantly on ephemeropteran nymphs, chironomid larvae, trichopteran larvae, and benthic algae. Predation and intimidation by the dace reduced the number of ephemeropteran nymphs and lowered the percentage of invertebrates on the upper surfaces and sides of the tiles. Consequently, dace increased the algal biomass through a trophic cascade. When dace were present, a disturbance did not reduce the numbers of invertebrates at the end of the experiment, probably because most invertebrates recolonized the tiles and new invertebrates rapidly colonized the pools. The manipulation of habitat heterogeneity reduced the number of trichopteran larvae, but did not affect other invertebrates that used all surfaces of the tiles. Consequently, trophic cascades were not damped by these changes of habitat heterogeneity and disturbance.     

The Effect of Live and Artificial Diets on Growth, Survival, and Trypsin Activity in Larvae of Penaeus indicus

In this study, partial and total replacement of live diets (microalgae and Artemia nauplii) with microencapsulated diets (MED) are demonstrated for larval culture of P. indicus . Slower growth and lower survival rate of larvae fed experimental MED were significantly improved by a supplement of 15 cells/μL frozen mixed algae (1:2, Tetrtaselmis and Skeletonema ) during protod stages (PZ1–PZ3). This low level of algal supplement to MED resulted in survival (85–92%) equal to that obtained from control live diets (91%) during protod stages. These significant improvements in larval growth and survival are likely to be due to higher larval digestive enzyme activities and hence more efficient digestion of the artificial diet by the larvae. Like other penaeids, P. indicus larvae show high total and tissue trypsin activities during PZ stages, with a peak at mysis stage 1 (M1), and a decrease during subsequent stages when fed on conventional live diets of algae followed by Artemia during mysis stages. Larvae fed 15 ceUs/μL mixed frozen algae in addition to MED demonstrated a significantly higher trypsin activity throughout herbivorous larval stages in comparison to larvae fed solely on MED. A freeze dried alga Rhinomonas reticulata incorporated into a MED at 23Vo (v/v) induced larval trypsin activity equal to that produced by live algae. Hence, the algal substances, which trigger digestive enzyme production, may be retained within the microcapsules. At mysis stages, however, addition of live prey (one Artemia/ mL) to cultures fed with MED significantly improved growth and survival although it depressed trypsin activity. For mysis stages it appears that the use of predigested ingredients is necessary to improve the digestibility of formulated diets.     

Growth,settlement and survival of Dicathais orbita (Neogastropoda,Mollusca) larvae in response to temperature,diet and settlement cues

The southern Australian whelk, Dicathais orbita, is a potential candidate for aquaculture, as both seafood and for bioactive compound production. Larval rearing experiments to determine the effects of temperature and diet on the growth and survival of D. orbita larvae under laboratory conditions comprised five different unicellular algal diets of two brown algal species; Isochysis galbana and Chaetoceros muelleri, two green algae; Tetraselmis seucica and Nannochloropsis oculata, and a mixture of all four strains for larvae maintained at 16 and 22°C. Absolute growth, specific growth rate (SGR) and survival were determined regularly. Larvae reared at 22°C on a mixed diet, or brown algae, performed significantly better than those reared on green algal diets alone. Preliminary trials with settlement cues were undertaken on different aged larvae to determine when larvae become competent. An array of natural cues (carrion, Xenostrobus pulex, adult mucus and Ulvella lens), as well as concentrations of KCl was tested. KCl(concentration of 20 mM) induced the greatest settlement, however, no larvae metamorphosed under the conditions provided. This study confirms long‐lived planktotrophic larval development for Dicathais orbita with higher development rates at the higher water temperatures. Further studies will optimize culture conditions and cues for settlement and metamorphosis.     

Molecular identification of macroalgal fragments in gut contents of the sea urchin <Emphasis Type="Italic">Hemicentrotus pulcherrimus</Emphasis>

In order to improve the efficiency of stock enhancement programs for the sea urchin Hemicentrotus pulcherrimus, information on food algal species, which affect growth and gonad production greatly, is necessary. Since it is difficult to identify species from the macroalgal fragments within the gut contents of the sea urchin by microscopic observation, we tried to apply a DNA barcoding method for gut contents analysis. We used a partial rbcL gene sequence for taxonomic section and newly designed primer sets, respectively, for brown algae and for red algae. Direct sequencing of the PCR products was carried out. Species identification was based on the phylogenetic relationship. We could objectively identify four species and two taxonomic groups (genus or family) in brown algae, and two species and four taxonomic groups in red algae from the gut contents. Sargassum hemiphyllum was the most abundant brown alga in the gut contents but was not dominant in the study site. The result showed the importance of identification to the species level. In addition, red algal epiphytes were detected with brown algal fragments. The DNA barcoding method will enable the researchers to verify the important role of epiphytes as a potential food source.     

Flocculated microalgae concentrates as diets for larvae of the tiger prawn Penaeus monodon Fabricius

Fresh algal culture is a major bottleneck in the aquaculture industry. Substitutes that are cost-effective and simplify hatchery procedures, such as algae concentrates need to be evaluated. Four species of alga – Chaetoceros muelleri , C. calcitrans , a tropical Skeletonema sp. and Thalassiosira pseudonana – were concentrated by flocculation, stored for 6 weeks at 4 °C and then compared with their fresh counterparts as feeds for Penaeus monodon larvae. The algae were fed at either high or low cell densities with no supplements.
Fresh C. muelleri promoted the highest survival, greatest weight gain and fastest development to mysis 1. Larvae fed this diet were twice as heavy as those fed most of the other diets. Concentrated C. muelleri or T. pseudonana promoted similar survival rates to that of larvae fed fresh C. muelleri although development rates were slower. Larvae fed fresh C. calcitrans had high survival and intermediate development, but those fed the concentrate had very poor survival and development. Skeletonema sp., whether in the fresh or concentrated form, was a poor diet for prawn larvae: it resulted in high mortality and slow development. Cell density did not affect survival or dry weight of larvae but did affect development in some cases. Flocculated algal concentrates show promise as replacement feeds for fresh algae.     

Implications of larval diet concentration on post-larval yield in a production scale flow-through system for scallops (Pecten maximus Lamarck) in Norway

In order to optimize Pecten maximus larval performance and post-larval yield, larvae were fed five algal concentrations in the range 3–20 cells μL^?1 in 2,800-L flow-through tanks without prophylactic antibiotics. Competent larvae were transferred to a commercial hatchery for settlement and provided uniform conditions for 4 weeks to observe effects. Increased diet concentration increased the sum of fatty acids (FA) in the total larval population, reaching 7 and 25 ng FA larvae^?1 at 3 and 16 cells μL^?1, respectively. The FA level in competent larvae was not affected by diet concentration and ranged from 30 to 46 ng larvae^?1. Increased diet concentration increased larval growth rate, and the larvae were ready to settle 5 days earlier when fed 16 cells μL^?1 compared to 3 cells μL^?1. Larval ingestion rate increased during life span and with increased larval diet concentrations, but a considerable amount (40–60 %) of the added algal cells was lost from the larval rearing tanks due to the seawater flow. There was no effect on larval survival, final post-larval shell height, % of competent larvae transferred to settlement, or total yield of post-larvae. Final mean post-larval shell height was 509 μm and 25.5 % of competent larvae settled, resulting in a final post-larval yield between 6.9 and 17.6 % of the initial number of d3 larvae. Competent larvae with similar FA content produced similar numbers of post-larvae independent of diet concentration, even if higher diet concentrations resulted in higher rates of larval development and metamorphosis.     

Assessment of coral reefs using herbivory/nutrient assays and indicator groups of benthic primary producers: a critical synthesis,proposed protocols,and critique of management strategies

• 1. Rapid assessment protocols for determining and monitoring the status of any given coral reef are provided and include measuring: (a) standing stocks of functional indicator groups, (b) herbivore populations, (c) water‐column nutrient levels, (d) tissue C:N:P ratios, (e) algal physiological‐response assays, and (f) herbivory assays. These measurements can reveal quantitative tipping‐point levels beyond which resilience to undesirable phase shifts begins to become critically reduced. Universal tipping‐point approximations are reviewed for inorganic nutrients, and posited for the first time for herbivory.
• 2. The relative roles of top‐down and bottom‐up controls in determining benthic community structure and the health of coral reefs are especially important management concerns. This paper specifically addresses the top‐down effects of herbivory and bottom‐up effects of nutrient enrichment on critical indicator groups, i.e. reef‐building corals, crustose coralline algae, dense turf algae and frondose macroalgae.
• 3. A predominance of (a) massive corals and calcareous coralline algae relative to frondose macroalgae and algal turfs indicates a healthy spatially heterogeneous condition reflecting low nutrients and high herbivory. An abundance of (b) frondose macroalgae illustrates the least desirable condition of elevated nutrient levels and reduced herbivory, possibly reflecting pollution in concert with destructive herbivore fishing practices. High coverage of (c) coralline algae suggests healthy high herbivory levels, but problems with elevated nutrients that are inhibitory to some corals. Domination by (d) dense turf algae indicates desirably low nutrient levels, but an inadequate herbivory component.
• 4. The fast growth and turnover rates of fleshy algae compared to other reef organisms highlight their value as early warning indicators of reef degradation.
• 5. From a management perspective, levels of herbivory and nutrients rank among the most useful quantitative indicators of coral reef resilience; whereas, the degree of degradation and mortality are inferred from the above functional indicator groups of benthic primary producers.

Published in 2006 by John Wiley & Sons, Ltd.     

Larval and post‐larval growth,spat production and off‐bottom cultivation of the smooth venus clam Chionista fluctifraga

Harvesting practices of the clam Chionista fluctifraga show a decline in commercial size and densities, but no strategies have been developed to maintain clam beds. Aquaculture represents an alternative for preserving this resource. Adult clams from commercial grounds were used as broodstock. Conditioning, induction of spawning, cultivation of larvae, settlement of eyed larvae and nursing of postlarvae were performed in the hatchery for producing spat. Larvae and postlarvae were used to measure increase in shell height and data were fitted to exponential growth models. Spat were placed in floating trays and maintained in off‐bottom cultivation for 9 months. Samples of clams and tissues were collected monthly to measure absolute growth, shell height increase and a condition index. Larvae, postlarvae and juveniles showed exponential growth patterns. Mean shell height increased about 0.030 mm day^?1 during larval and post‐larval stages and 0.049 mm day^?1 during field cultivation. Pediveligers (height 215 ± 83 μm) entered metamorphosis at days 9–13 after fertilization, and postlarvae reached 3011.7 ± 325.5 μm (height) at day 60. After field cultivation, survival was about 95%; juvenile shell height was 20.6 ± 2.2 mm, and total weight was 5.3 ± 0.7 g. Growth rates were superior to natural conditions and the condition index was high throughout the study. Our results show that spat of C. fluctifraga can be produced in the hatchery, and that field production can be maintained in off‐bottom trays until reaching commercial size. Aquaculture activities for this species need to be established and evaluated.     

Influence of algal cell size on filtration and ingestion rates during different larval stages of the yellow neck clam,Paphia malabarica Chemnitz

Filtration rate and ingestion rate of different stages of Paphia malabarica larvae (D‐shape, (80 μm), Umbo (120 μm) and veliger (180 μm)) were determined in relation to feeding on various micro algae. The micro algae tested were Nannochloropsis salina, Isochrysis aff. galbana, Dicrateria inornata, Tetraselmis gracilis and Chaetoceros calcitrans at 5 or 10 × 10³ cells mL^?1. Both filtration and ingestion rate of micro algae tested were increased with increasing larval size; however, at all larval stages, C. calcitrans resulted in lower filtration and ingestion rate. Of the algal diets tested, P. malabarica larvae showed greatest filtration rate and ingestion rate with N. salina. Maximum filtration rate for N. salina was 15.7, 26.3 and 33.9 μL h^?1 and highest ingest rate was 15, 92 and 177 cells larva^?1 h^?1 in D shape larvae, umbo and pediveliger, respectively. Filtration rate and ingestion rate of N. salina were always higher than those other algal species tested because of its small cell size (2 μm).     

Age distribution of the sea urchin Strongylocentrotus nudus (A. Agassiz) in relation to algal zonation in a rocky coastal area on Oshika Peninsula, northern Japan

ABSTRACT: The age distribution of the sea urchin Strongylocentrotus nudus in relation to algal zonation was studied in a sublittoral rocky area on Oshika Peninsula, northern Japan, from June 1995 through to August 1996. The algal zonation observed there extends from a shallow area of cobbles to deeper areas dominated successively by Sargassum yezoense , Eisenia bicyclis and, finally, crustose coralline red algae. One-year-old sea urchins occurred only on the cobbles and crustose corallines in contrast to the presence of 2-year-old individuals from all areas and the restricted distribution of individuals aged 3 years and over to Eisenia and crustose corallines. Calculated mean body sizes in the Eisenia area became larger after the age of 2 years compared with those in the area of crustose corallines. Spawning was ascertained histologically in both the Eisenia and crustose coralline areas, although gonad indices were higher in the former area than in the latter throughout the year. Gut contents were dominated by E. bicyclis in the Eisenia area, and by crustose coralline red algae and small algae in the crustose coralline area. Thus, the sea urchin may settle most abundantly on crustose corallines and lives there for 1–2 years. Thereafter, they expand their habitat toward the Eisenia area, where there is richer sources of food for attaining a higher growth rate and to generate heavier gonads.     

Marine reserve site selection along the Abel Tasman National Park coast,New Zealand: Consideration of subtidal rocky communities

At present, marine reserves do not represent the full range of community types throughout New Zealand. To assist with the placement of a marine reserve along the Abel Tasman National Park coast (northern South Island), dominant subtidal laminarian and fucoid algae, echinoids and herbivorous molluscs were quantitatively investigated. Results from 100 quadrats collected from 19 random transects at six selected sites showed that algae and grazer assemblages varied between granite and limestone substrata. Granite had a high percentage cover of crustose coralline algae (mean 82%–90%), a sublittoral fringe of brown macroalgae and no Ecklonia radiata or red foliose algae. Limestone sites were distinguished by a relatively low percentage cover of coralline algae (mean 13%) and high cover of foliose red algae and E. radiata (2%–36% cover and 0.2–13.9 stipes m^?2, respectively). On limestone, molluscs Turbo smaragdus and Cookia sulcata, and the echinoid Evechinus chloroticus were larger than those on granite. On limestone sites with little macroalgae, herbivore size was intermediate. Grazers were more abundant on granite than limestone (mean 34.6 m^?2, and 10.8 m^?2 respectively). Differences in herbivore composition were recorded between granite substrata, while both algal and herbivore composition varied between limestone sites. We suggest that a variety of environmental factors including substratum influence algal and herbivore assemblages along the Abel Tasman coast. It is recommended that selection of a marine reserve site or sites along the coast of Abel Tasman National Park recognizes differences in community structure both between and within limestone and granite substrata.     

Larval rearing of calico scallops, Argopecten gibbus, in a flow-through system

A flow-through (FT) culture system is described for calico scallop, Argopecten gibbus, larvae. Its performance was assessed by larval survival rate, shell growth, settlement rate and post-larval shell growth for the duration of larval life (13 days). Comparisons were made with larvae reared in standard static system (S). Effect of increased larval density on FT performance was also investigated. With comparable larval densities, survival rate of Day 2 larvae to pediveliger stage was similar in both larval rearing systems. Shell growth for FT-reared larvae was comparable or significantly higher than in the static system (P < 0.01). Settlement rate of pediveligers was comparable for both systems, averaging 30.7%, and no significant difference was seen in shell growth of FT- and static-reared pediveligers. Increased initial larval density did not affect survival rate in FT, but did negatively affect larval shell growth, settlement rate and post-larval shell growth yielding lower growth and minimal settlement rate (10.9 ± 2.8%) compared to the static system. This FT system was successful as larval rearing system, optimising space allocation in the hatchery, reducing labour, and eliminating the use of antibiotics. Optimising initial larval density within the system needs to be investigated in association with food ration.     

Evidences of the intertidal red alga Grateloupia turuturu in turning Vibrio parahaemolyticus into non-culturable state in the presence of light

Grateloupia turuturu, previously known as Grateloupia doryphora, has been widely reported to be an invasive algal species. There are no studies to relate the impact of its existence on its surrounding environment. In this paper, we present our results to show that about 70% of individuals collected from the field could turn Vibrio parahaemolyticus into non-culturable state on both selective (TCBS) and non-selective (2216E) culture medium in 24 h in the presence of light in live algal culture. Total bacteria counts on TCBS and 2216E plates dropped from the initial 565 (± 174) and 1192 (± 60) cfu ml^− 1 respectively to zero in 24 h. This effect disappeared when the alga was grown in darkness. The same effect was not found in two other intertidal macroalgae Laminaria japonica and Palmaria palmata. Further tests showed that the settlement ability of bacteria in seawater was impaired significantly in the presence of this alga in comparison with three other algal species.     

中街山列岛保护区底栖海藻分布与资源特征

2008年7月至2010年9月对舟山中街山列岛的底栖海藻资源进行了调查研究,共鉴定底栖海藻4门54属78种。其中蓝藻门1属1种,绿藻门9属15种,红藻门32属47种,褐藻门12属15种。本地区新记录5种。中街山列岛底栖海藻以暖温带性的海藻为主,垂直分布规律表现为底栖海藻种数从高潮带向低潮带剧增。与史料相比,中街山列岛底栖海藻资源有较大幅度的减少。     

Instantaneous effect of dibromomethane on metamorphosis of larvae of the sea urchins Strongylocentrotus nudus and Strongylocentrotus intermedius

A volatile chemical, dibromomethane (DBM), produced from red coralline algae is known as a chemical inducer of larval metamorphosis of the sea urchin Strongylocentrotus nudus. We performed experiments exposing DBM to the larvae of S. nudus and Strongylocentrotus intermedius through a hydrophobic membrane. Metamorphic rates resulting from different diluted DBM solutions and exposure times were ascertained. The highest metamorphic rate, more than 80% in both species, was found after 1 h exposure to 1/2 diluted DBM. With this dilution, more than 80% of S. nudus and S. intermedius larvae metamorphosed 1 h after start of the experiment after only 10 and 5 min exposure, respectively, which corresponded to the low concentrations of 52–61 ppm and 34–43 ppm DBM by GCMS analysis, respectively. These findings suggest that DBM has an instantaneous effect on high success of metamorphosis of larvae of S. nudus and S. intermedius.     

Settlement behavior of American lobster (Homarus americanus): effect of female origin and developmental temperature

The benthic settlement success of American lobster (Homarus americanus) postlarvae is a key factor in population dynamics, with the temperature being a key factor. Given the spatial distribution of the species, its pelagic larvae probably encounter various thermal zones during development. Little information is available on the ability of lobster larvae to acclimate to temperature or if this ability varies among geographic areas. The main objectives of this study were to characterize (i) the settlement behavior of the postlarvae in relation to (a) temperature during larval development and (b) the geographic origin of the maternal parent and (ii) the behavioral response of postlarvae with different thermal histories in the presence/absence of a thermocline. Results did not support the hypothesis of thermal adaptation among local populations, as settlement behavior of postlarvae did not differ among females from different geographic regions. In contrast, larval survival and settlement behavior and postlarval energetic conditions varied with development temperature. Behavioral plasticity in the benthic settlement was observed in relation to temperature structure of the experimental water column. This study suggests that there may be links between development temperature and the natural variability in survival and settlement of American lobsters. Findings emphasize the need for an integrated approach in lobster recruitment studies with the inclusion of behavior in dispersion models.     

Larval settlement of the tropical abalone, Haliotis asinina Linnaeus, using natural and artificial chemical inducers

Many kinds of chemical and biological materials have been used as inducers of settlement of abalone larvae, as well as other species of marine gastropods, with responses being highly variable, even to the same chemical cue. The present study tested chemical inducers, γ-aminobutyric acid (GABA), δ-aminovaleric acid (5-AVA) and l -glutamic acid (GA) and the effects they have on larval settlement of Haliotis asinina . Additionally, a relatively inexpensive commercial substance, monosodium glutamate (MSG), was trialed. The datum provided shows all chemicals to be active inducers of settlement in this study, in order of effectiveness of 5-AVA, GABA, MSG to GA. Induction as adjudged from larval numbers settled was best at 6 h 62%, with 10⁻¹ mM 5-AVA. At 24 h, induction was the highest at 78% when exposed to 10⁻² mM 5-AVA. Larvae that were allowed to settle up to 72 h showed the highest numbers of settled larvae, and declined back to 60% when exposed to 10⁻² 5-AVA and 10⁻¹ mM GABA respectively. Monosodium glutamate, although third in settlement standings would bypass the other chemicals, with regard to cost versus yield. The assessment of settlement surface, rough or smooth proved to be irrelevant, which had no significant impact on larval settlement.