John C. Roff

National frameworks for marine conservation — a hierarchical geophysical approach

1. Development of environmental protected areas has been driven ‘more by opportunity than design, scenery rather than science’ (Hackman A. 1993. Preface. A protected areas gap analysis methodology: planning for the conservation of biodiversity. World Wildlife Fund Canada Discussion Paper; i–ii). If marine environments are to be protected from the adverse effects of human activities, then identification of types of marine habitats and delineation of their boundaries in a consistent classification is required. Without such a classification system, the extent and significance of representative or distinctive habitats cannot be recognized. Such recognition is a fundamental prerequisite to the determination of location and size of marine areas to be protected. 2. A hierarchical classification has been developed based on enduring/recurrent geophysical (oceanographic and physiographic) features of the marine environment, which identifies habitat types that reflect changes in biological composition. Important oceanographic features include temperature, stratification and exposure; physiographic features include bottom relief and substrate type. 3. Classifications based only on biological data are generally prohibited at larger scales, due to lack of information. Therefore, we are generally obliged to classify habitat types as surrogates for community types. The data necessary for this classification are available from mapped sources and from remote sensing. It is believed they can be used to identify representative and distinctive marine habitats supporting different communities, and will provide an ecological framework for marine conservation planning at the national level. Copyright

Trout Biomass and Habitat Relationships in Southern Ontario Streams

Abstract We examined relationships between the biomass of trout (species of Salvelinus and Salmo) and physical and biological habitat variables in streams to identify habitat factors that might limit trout biomass. Thirty sites were chosen to span a wide array of habitat types. At each site we measured a large number of habitat variables representing instream cover, substrate, stream morphology and velocity, stream temperature and food availability. Two habitat quality index models developed by Binns and Eiserman for Wyoming streams accounted for only 6.7 and 9.2% of the variation in trout biomass at Ontario stream sites. Different factors must limit trout biomass in Wyoming streams than in Ontario streams. Regression and discriminant function analyses indicated that trout biomass in southern Ontario is correlated with microcommunity biomass (measured as ATP of the suspended solids, and representing bacteria, fungi, and algae), percent pool area, mean maximum summer temperature, biomass of small benthic i...

Annual biomass and production of the oceanic copepod community off Discovery Bay, Jamaica

Monthly samples were collected in oceanic waters off Discovery Bay, Jamaica, in 60- and 200-m vertical hauls, using 200- and 64-μm mesh plankton nets, from June 1989 to July 1991. Length-weight regressions were derived for twelve genera of copepods (R2=0.79 to 0.97). For eight occasions spanning the study period, biomass estimates generated from these length-weight regressions differed by only 3% from direct weight determinations. The mean ash content of copepods was 7.1%, and the energy density was 20.8 kJ g-1 ash-free dry weight (AFDW). Mean annual biomass of the total copepod community in the upper 60 m was 1.83 mg AFDW m-3 (range 1.14 to 2.89 mg AFDW m-3), and for the 200-m water column was 0.96 mg AFDW m-3 (range 0.12 to 1.99 mg AFDW m-3). Estimates of generation times for five common taxa ranged from 16.1 to 33.4 d. None of the taxa investigated displayed isochronal development; in general, stage duration increased in later copepodite stages. Weight increments showed a significant decrease in later copepodite stages, but with strong reversal of the trend from stage 5 to adult female in most species. Daily specific growth rates also declined in later copepodite stages, and ranged from 1.49 d-1 in stage 1–2 Paracalanus/Clausocalanus spp. to 0.04 in stage 5-female of Oithona plumifera. Progressive food limitation of somatic copepodite growth and egg production is postulated. Naupliar production was 50.4 to 59.5% of copepodite production, and egg production was 35.1 to 27.7% of copepodite production in the 60-and 200-m water columns, respectively. Total annual copepod production, including copepodites, nauplii, eggs and exuviae, was 160 kJ m-2 yr-1 for the upper 60 m and 304 kJ m-2 yr-1 for the upper 200 m. Secondary production of the copepod community in oceanic waters off Discovery Bay approaches 50% of the corresponding value in tropical neritic waters.

Size-weight relationships and biomass of tropical neritic copepods off Kingston, Jamaica

Nine genera of neritic tropical copepods were collected near Lime Cay, Jamaica, between July 1985 and January 1987. Length-weight regressions were derived for each genus (R2=0.74 to 0.98), for all calanoids combined (R2=0.88), and all cyclopoids combined (R2=0.85). Width-weight regressions were also derived for the same genera but coefficients of determination were generally lower (R2=0.52 to 0.98) and were much lower forOithona spp. (R2=0.21). Over a 12 mo period, biomass estimates generated from these length-weight regressions differed by only 3% from direct weight determinations. There were no significant annual variations in prosome lengths for copepodite Stages 1 to 5 inCentropages velificatus, Paracalanus aculeatus orTemora turbinata; prosome lengths in femaleT. turbinata did significantly vary seasonally. No significant seasonal differences in length-weight relationships were observed forC. velificatus. The mean ash content of mixed copepod samples was 6.4%, and the energy density was 25.0 kJ g−1 AFDW. No significant loss of weight was observed 10 mo after preservation in 10% formalin.

Annual structure of the copepod community and its associated pelagic environment off Discovery Bay, Jamaica

Monthly samples were collected in oceanic waters off Discovery Bay, Jamaica, in 60- and 200-m vertical hauls, using 200- and 64-μm mesh plankton nets, from June 1989 to July 1991. Sixty-nine species of copepods were identified: nauplii, copepodites and adults were separately enumerated. Total copepod abundances (all stages) ranged from 695 to 4120 m-3 in the upper 60 m, and from 483 to 3319 m-3 in the 200-m water column, without any clear seasonal pattern. With the exception of temperature, no seasonal variations in physico-chemical (chlorophyll a, S‰, particulate organic carbon, particulate protein) or biological variables were evident. Nauplii, adults and copepodites of selected taxa, and two chaetognath species, showed no significant variations in body length. Significant variantions in reproductive index were detected for several species, but without seasonal trends; many species appear to be continuous or intermittent breeders. There was no evidence of seasonal pattern in overall community composition or diversity, or evidence of changes due to water mass advection. The copepod community can be divided into a recurrent group of 13 (at 60 m) to 17 (at 200 m) “perennial” species, present year-round, and associated “ephemeral” groups of 1 to 3 species, present randomly for 1 to 4 consecutive months. The most plausible explanation of these patterns is that broad areas of the Caribbean Sea are dominated by the community of perennial species, while the ephemeral species represent the superimposed influence of local mesoscale gyres.

Size paradigms in copepod communities: a re-examination

A longstanding view in zooplankton research has been that large copepods are the important members of most communities. It has also been thought that warm water communities contain smaller copepods than temperate waters, with cold polar waters containing large species. We present copepod size spectra from detailed microscopic analysis of tropical and temperate locations, to challenge these paradigms. While the size range of copepods does increase with decreasing temperature and with depth into oceanic waters, the fundamental attributes of the size spectra are similar. Small copepods and early developmental stages dominate all communities.

Abundances, growth rates, and production of tropical neritic copepods off Kingston, Jamaica

Weekly samples were collected near Kingston, Jamaica in 27 m vertical hauls, using 200 and 64µm mesh plankton nets, from July 1985 to January 1987. Thirtytwo copepod species were identified; nauplii and all copepodite stages were enumerated. Total copepod abundance ranged from 2.56 to 87.3 × 104 m−2. The annual abundance cycle was bimodal with peaks in October–November and May–June corresponding to the rainy seasons. Mean annual copepodite biomass was 0.15 g AFDW m−2 ranging from 0.03 to 0.41 g AFDW m−2. Mean generation time (from egg to adult) at 28°C was 19.5 d for the common speciesCentropages velificatus, Paracalanus aculeatus, andTemora turbinata. Isochronal development was demonstrated for copepodites ofP. aculeatus andT. turbinata, but not forC. velificatus. Mean daily specific growth rates (G) were 0.63, 0.63, and 0.48 d−1 forC. velificatus, P. aculeatus, andT. turbinata, respectively. In general, daily specific growth rates decreased in the later copepodite stages. Thus, it is postulated that growth of later stages and egg production may be food limited. Annual copepodite production was estimated as 419 kJ m−2 yr−1, while annual exuvial production and naupliar production were 35 and 50 kJ m−2 yr−1, respectively. Egg production was estimated as 44% (184 kJ m−2 yr−1) of the total copepodite production. Thus, mean total annual copepod production was 688 kJ m−2 yr−1. This estimate is within the range of copepod production estimates in coastal temperate regions.

Phytoplankton ecology and production in the Red Sea off Jiddah, Saudi Arabia

Phytoplankton species diversity was generally high throughout the year at two stations in the central Red Sea (Lat. 21°30′N), and species of Mediterranean and Indian Ocean origin were represented, reflecting seasonal monsoonal influence. Low phytoplankton cell numbers accompanying high production rates suggest the significance of nanoplankton or picoplankton which were not enumerated. Production was high year-round, and averaged 390 gC m-2 yr-1, despite the virtual lack of nutrient additions from rainfall or land runoff or demonstrable upwelling. Highest nutrient levels followed the first seasonal peak of production. Biomass and production were seasonally bi- or tri-modal, with major peaks in December–February and June–August, 1977–1978. The first peak of production, populated by diatoms, occurred at the onset of seasonal stratification, but the second peak, populated by Trichodesmium spp., occurred at the height of seasonal stratification and lowest nutrient concentrations. There is no clear relationship between the timing of monsoon activity and the annual production cycle.

Characterization of Chitobiase from Daphnia magna and Its Relation to Chitin Flux

Chitobiase (N-acetyl-β-D-glucosaminidase) activity has been measured and partially characterized in Daphnia magna. The pH optimum is approximately 5.5, and the temperature optimum is approximately 45°dg-5° dgC, as determined from crude extract. The enzyme remains stable even after a 2-h incubation at 20° or 40°C. The Km determined for methylumbelliferyl-N-acetyl-β-D-glucosaminide and p-nitrophenyl-N-acetyl-β-D-glucosaminide is 61.5 μM and 359.6 μM, respectively. Activation energy is significantly less for lower temperatures (5°-18°C) than for higher temperatures (18°-40°C). Investigation of the effect of acclimation temperature on chitobiase activities reveals no significant differences in activities between 10° and 18°C for populations raised at different temperatures. A similar pattern in the Q10s was also observed. There was no evidence of any isozyme effect for populations raised at 6°, 10°, 18°, or 25°C Attempts to protect the enzyme with various osmotic solutions and the results of differential centrifugation suggest that at least some of the enzyme is packaged in vesicles and/or lysosomes. Maximal chitobiase activity of asynchronous populations fed ad lib. overestimates the flux of N-acetyl-β-D-glucosaminide (NAG) from the old to the new cuticle by approximately 100×. Chitobiase activity modulates significantly over the molt cycle in Daphnia, with a fivefold increase in activity 6-0 h before molt. This suggests that chitobiase activity may provide an index of molt rate in asynchronously molting populations.

Annual abundance and biomass of aloricate ciliates in tropical neritic waters off Kingston, Jamaica

The daily abundance of aloricate ciliates at Lime Cay, Jamaica, a shallow neritic site, ranged from 29 to 118 × 106 m−2 (0.97 to 3.93 × 106 m−3) between November 1985 and November 1986. Biomass was converted to kilojoules (1 kcal=4.1855 kJ) assuming 42% carbon, 20.15 kJ (g dry wt)−1, and 20% cell shrinkage. Biomass ranged from 0.40 to 3.00 kJ m−2 (13.3 to 100 J m−3; 0.28 to 2.08µg C l−1) with an annual mean of 1.11 kJ m−2 (36.8 J m−3; 0.764µg C l−1). Nanociliates (<20µm equivalent spherical diameter, ESD) dominated abundance, but microciliates (> 20µm ESD) dominated biomass.Strombidium, Strobilidium, Tontonia andLaboea species were conspicuous taxa. Annual production estimates of the aloricate assemblage, based on literature growth rates, ranged from 404 kJ m−2 yr−1 (37 J m−3 d−1) to 1614 kJ m−2 yr−1 (147 J m−3 d−1). A compromise estimate of 689 kJ m−2 yr−1 (i.e., 63 J m−3 d−1) is comparable to other estimates from tropical and subtropical regions. A model of annual energy flow through 11 planktonic compartments suggests the total ciliate assemblage (aloricates and tintinnines) to be as productive as metazoan herbivores and metazoan carnivores.