Choices Of Feeding Habitat By Sebastiscus Marmoratus In The Protected Ma'an Archipelago

Coastal waters habitats?such as the rocky reef habitat and kelp beds?have high primary productivity,providing shelter habitats and nursery ground for many marine fish,in particular the rocky reef fish.These habitats are linked primarily through fish feeding activities.Feeding habitat is the most important habitat for fish.Studies on fish feeding habitat selection can help to clarify ecological functions of habitat and habitat preference for fish,and have important guiding significance to help carry out the proliferation of marine biological resources,as well as establishing protective measures of the ecological systems based on resource management.In this study,we compared the basic biological characteristics,feeding ecology,and biological composition of potential diets of S.marmoratus as well as the characteristics of stable carbon and nitrogen isotopes in different typical habitats?such as rocky reef habitat,kelp beds,marine ranch and mussels farming?.These were assessed using stomach contents analyses?SCA?and stable isotope analyses?SIA?of carbon and nitrogen.We clarified the mechanism of S.marmoratus's selection of feeding habitat based on growth cycle,and the different feeding habitat contribution rate to their required energy supply for growth.We performed a systematic analysis of the feeding habitat choices of S.marmoratus in their typical habitats,our conclusions are as follows.The body length range of S.marmoratus in the protected Ma'an Archipelago area was from 1.9cm to 19.1cm with an average length of7.5cm.Average body length of S.marmoratus in the mussels farming?3.8cm?is significantly lower than the rocky reef habitat?7.6cm?,kelp beds?7.8cm?and marine ranch?8.2cm?.Growth parameters a and b of S.marmoratus in the protected Ma'an Archipelago area are 0.028 and 3.00,respectively.There were significant differences among the rocky reef,kelp bed,and marine ranch and mussels farming?P<0.05?.The growth rate was positive allometric in the rocky reef and marine ranch,and negative allometric in the kelp bed and mussels farming.There are a wide range of feeding species of S.marmoratus in rocky reef habitat,kelp beds,and marine ranch within the Protected Ma'an Archipelago area,with 42 species of 10 types,35 species of 10 types,and23 species of 7 types,respectively.However,the mussels farming only has3 species of 2 types.The feeding species of S.marmoratus change to a certain extent along with the increase of body length.Among them,the feeding rate of S.marmoratus changed obviously with the increase of body length in the rocky reef,kelp beds,and marine ranch?P<0.05?,but not in the mussels farming?P>0.05?.The?¹³C and?¹⁵ N results from the rocky reef habitat,kelp beds,marine ranch,and mussels farming in the Protected Ma'an Archipelago area were?-16.10±0.68?‰and?7.71±0.98?‰,?-16.38±0.69?‰and?7.15±1.30?‰,?-15.50±0.47?‰and?8.69±1.10?‰,?-16.18±0.62?‰and?6.81±1.07?‰,respectively.The average trophic levels of S.marmoratus were?3.11±0.29?,?2.95±0.39?,?2.84±0.32?and?3.40±0.33?,respectively.There was a significant correlation between the trophic level of S.marmoratus with body length in the rocky reef habitat,kelp beds and mussels farming?P<0.05?,but not in the marine ranch?P>0.05?.Combined with the stomach contents analyses?SCA?and stable isotope analyses?SIA?,the key length of feeding conversion in S.marmoratus was 7.0cm,10.0cm,and 12.0cm.There are 13 species,18 species,26 species and 7 species of potential food of S.marmoratus in the rocky reef habitat,kelp beds,marine ranch,and mussels farming respectively,in the Protected Ma'an Archipelago area.There are 6 diet species groups in the rocky reef habitat,kelp beds,and marine ranch,and 4 in the mussels farming.In the rocky reef habitat the S.marmoratus in the<10.9cm group mainly preyed on echinoderm,and those in the>11.0cm group mainly preyed on mollusca.In the kelp beds,the S.marmoratus in the 3.0cm-6.9 cm group mainly preyed on amphipoda,those in the 7.0cm-10.9cm group mainly preyed on crabs,and those in the>11.0cm group mainly preyed on shrimp.In the marine ranch,the main diet species of all body length?4.0cm-16.9cm?of S.marmoratus were amphipoda.In the mussels farming,the S.marmoratus in the 3.0cm-6.9cm group mainly preyed on amphipoda.With increasing body length,S.marmoratus shows three feeding habitat selection models.Under the first model,it grows to 7.0 cm in the mussels farming and rocky reef habitat before migrating to the kelp beds,growing to 11.0 cm,and then moving to the marine ranch.Under the second model,it grows to 7.0 cm in the mussels farming and then migrates directly to the marine ranch.Under the third and final model,it grows to 7.0 cm in the rocky reef,migrates and grows to 11.0 cm in the kelp beds,and then moves to the marine ranch.