Estimating the abundance of clustered and cryptic marine macro-invertebrates in the Galápagos with particular reference to sea cucumbers

Estimating the abundance of marine macro-invertebrates is complicated by a variety of factors: 1) human factors, such as diver efficiency and diver error; and 2) biological factors, such as aggregation of organisms, crypsis, and nocturnal emergence behavior. Diver efficiency varied according to the detectability of an organism causing under-estimation of density by up to 50% in some species. All common species were aggregated at scales from 10-50 m. Transects need to be long enough to transcend the scale of patchiness to improve accuracy. Some species of sea urchins and sea cucumbers (pepinos) which are cryptic by day emerged at night so that daytime censuses underestimated their abundance by up to 10 times. In the sea cucumber fishery, estimates of abundance need to be made at the scale of the population, i.e. at hundreds of km. A strategy for this is proposed

Investigator group expedition 2006: Habitat-dependent foraging behaviour and diet of the scalyfin, Parma victoriae, in South Australia

The foraging behaviour, territory size and diet of the scalyfin, Parma victoriae, were studied at three sites in South Australia. Two sites were in Ecklonia habitat on an exposed coast, one of them, Site 1, in a marine reserve at West I., and the other, Site 2, in an intensely fished area at The Bluff, Victor Harbor. The third, Site 3, was sheltered, in a fucoid community in Groper Bay, Flinders I., in the eastern Great Australian Bight. The algal food supply was highest at the reserve site (1), and lowest at the sheltered site (3). The scalyfin spent a greater proportion of time foraging, and a lower proportion of time sheltering, at the reserve site (1), than at the Bluff site (2). At Site 3, territories were about seven times larger than at the other two sites, and fish spent a higher proportion of time in defence and aggressive interactions than at the other sites. The diet at all sites was predominantly browsed rhodophytes, but at Site 3 the rhodophytes eaten were almost entirely epiphytic on fucoid algae and in low abundance. At the exposed sites (1, 2), where food algae were patchy, scalyfin removed Ecklonia sporophytes experimentally placed in their territories, but not at Site 3, dominated by fucoids. At the exposed sites they employed a saltatory foraging mode, whereas at Site 3 they adopted a cruise search foraging behaviour over their larger territories. Both modes seem optimal in their respective habitats.Shepherd, S.A.; Clark, M. and Ferguson, G.http://adelaideaus.library.ingentaconnect.com/content/rssa/trssa/2008/00000132/00000002/art0000

Long-term changes in macroalgal assemblages after increased sedimentation and turbidity in Western Port, Victoria, Australia

The long-term impacts of declining water quality from coastal development on macro-algal communities can be devastating, but are rarely known because of lack of baseline studies. This study examines the effect of increased sediment and reduced water quality over 35 years in an Australian temperate coastal embayment. The algal assemblage on Crawfish Rock in northern Western Port was surveyed in 1967–1971 and in 2002–2006. During the 1980s, water quality declined following large-scale seagrass loss. In 1971, the Rock had a rich algal flora with 138 recorded species, including 97 species of Rhodophyta. The biomass and cover of canopy and understorey species were measured at sites of strong and slight current on a depth gradient. In 1971, fucoid or laminarian canopy species were dominant from ~1–8 m depth, and an algal understorey extended from the intertidal zone to ~12–13 m depth. In 2002–2006 the canopy species extended to only 3 m depth and the algal understorey to ~4 m depth, and 66% of the algal species had disappeared, although a few additional species were present. Persistent, sediment-tolerant species included several phaeophycean canopy species, some chlorophytes (Caulerpa spp.) and a few rhodophytes.Scoresby A. Shepherd, Jeanette E. Watson, H. Bryan S. Womersley and Janet M. Care

Early-Stage Diabetic Neuropathy Reduces Foot Strength and Intrinsic but Not Extrinsic Foot Muscle Size

Background. Tracking progression of diabetic peripheral polyneuropathy (DPN) is usually focused on sensory nerves and subjective testing methods. Recent studies have suggested that distal muscle atrophy may precede sensation loss. Methods to objectively measure distal muscle size and strength are needed to help understand how neuropathy affects muscle function. Purpose. To evaluate individual intrinsic and extrinsic foot muscle sizes and functional foot strength in participants with DPN. Methods. Thirty individuals participated in this cross-sectional study (15 DPN and 15 matched controls). Sizes of 10 separate muscles of the lower leg and foot were measured using ultrasound imaging. Functional foot strength was also quantified using custom great toe and lateral toe flexion tests along with a doming test. Muscle size and strength metrics were compared between groups using ANOVAs and paired t-tests (α=0.05). Correlations between strength and relevant muscle sizes were also evaluated. Results. The sizes of all four intrinsic foot muscles were smaller in individuals with DPN (p≤0.03), while only one (toe extensor) of the six extrinsic muscles was smaller (p<0.01). Great toe flexion (p=0.03) and lateral toe flexion (p<0.01) strengths were decreased between groups and showed moderate to strong correlations (0.43≤r≤0.80) with several corresponding intrinsic muscle sizes. The doming strength test did not show any difference between groups and was moderately correlated with one muscle size (r=0.59). Conclusion. Diabetic peripheral polyneuropathy affects intrinsic muscles before extrinsics. Ultrasound imaging of individual muscles and functional toe flexion tests can be used clinically to monitor DPN progression and foot function. Participants need to be trained in the doming test before a relationship can be established between this test and DPN foot function. Future studies should include muscle quality measurements to better understand characteristics of affected muscles