Biodiversity differentials between the numerically-dominant macrobenthos of seagrass and adjacent unvegetated sediment in the absence of sandflat bioturbation

Functional uniformity underlies the common spatial structure of macrofaunal assemblages in intertidal seagrass beds

“…Nevertheless, it was evident that the relative importance of the individual shared dominant groups was significantly different across localities, including at the otherwise similar Knysna and North Stradbroke, and even varied across sites within the latter locality: the details varied from place to place without changing the overall pattern of construction. The single most important group at the South African site was surface‐deposit collecting (spionid and cirratulid) polychaetes, whereas in Queensland overall it was microphytobenthos‐grazing microgastropods; indeed, such microgastropods were effectively absent from the specific South African site investigated by Barnes (), although they were the dominant components at other nearby sites (Barnes & Barnes, ). Within the Queensland locality, the single most important group also differed between the three component sites: surface‐deposit‐feeding worms at one, microphytobenthos‐grazing microgastropods at another, and omnivorous peracaridan crustaceans at the third.…”

“…Comparable data on the taxa comprising each benthic macrofaunal assemblage and on their relative importance were obtained from the datasets underlying recent published work in intertidal Zosterella habitats carried out at equivalent times of the year (Wlodarska‐Kowalczuk et al ., ) and with the same methodology: (1) on Scolt Head Island (within the Scolt Head National Nature Reserve) in the northwestern European North Sea at 53°N01°E (Barnes & Ellwood, ; Barnes, ), (2) at Knysna (within the Garden Route National Park) on the Indian Ocean coast of South Africa at 34°S23°E (Barnes & Ellwood, , ; Barnes, ; Barnes & Barnes, ) and (3) on North Stradbroke Island (within a Habitat Protection Zone of the Moreton Bay Marine Park) Queensland at 27°S153°E (Barnes & Barnes, ; Barnes & Hamylton, ; Barnes, ). All sites are hence enclosed within areas of high conservation status.…”

Context dependency in the effect of Ulva‐induced loss of seagrass cover on estuarine macrobenthic abundance and biodiversity

“…The presence of occasional mature clumps of Z. capensis was used to confirm the former extent of the seagrass bed. An additional series of three stations (each of 10 core samples, as described earlier) was also worked at the central‐channel/lower‐shore node to provide sufficient data to compare with that taken from near there in a pre‐existing unvegetated area in 2014 (Barnes & Barnes, ).…”

“…Macrobenthic assemblages present at the various nodes in 2018 were compared univariately and multivariately with the equivalent data from the same nodes in 2011, as well as from the 2014 Steenbok Channel seagrass versus bare sediment site of Barnes and Barnes (), in all cases based on abundance rather than occupancy data (Beck, Holloway, & Schwanghart, ). Comparison was via the following routines in PAST 3.14 (Hammer, Harper, & Ryan, ): analysis of similarity (ANOSIM), similarity percentage (SIMPER) and ordination by non‐metric multidimensional scaling of Bray–Curtis (equal to abundance‐based Sørensen) similarity, all with 9,999 permutations.…”

Seagrass macrofaunal abundance shows both multifractality and scale-invariant patchiness

“…The observed maximum at Deanbilla of 51 ind. core -1 is equivalent to some 9,500 m -2 , which would be regarded as a near average macrofaunal density in some of the South African Z. capensis beds studied by Barnes and Barnes (2014) and to be a very low abundance for the macrofauna of North Sea Z. noltei beds (Barnes and Ellwood, 2011). In other words, re-running Margalef's (1968Margalef's ( , 1975 hypothesis of a ladder of ecosystem maturity, severe top-down control might be expected to prevent the attainment of order and a self-organised state.…”